JPH0931225A - Readily adhering polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a readily adhering polyester film which is excellent in coating appearance, adhesion and antistatic properties and useful as a magnetic card by combining a specific surfactant with a phosphoric ester based antistatic agent. SOLUTION: Polyester film (preferably a white film containing a white pigment, having a thickness of >=20μm) is coated, at least on its one surface, with a coating material (preferably an aqueous coating material) comprising (A) a phosphoric ester salt antistatic agent such as sodium dioctyl phosphate, (B) a surfactant with an HLB of <=12 such as polyoxyethylene nonyl ether and (C) a binder of at least one kind selected from acrylic copolymers and polyester copolymers to form the objective easily adhering coating film (preferably 0.01-1μm thick). The proportions of the components A, B and C are 5-40wt.%, 1-20wt.% and 94-40wt.%, based on the total amount, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily adhesive polyester film, and more specifically, a coating appearance, an easily adhesive property,
The present invention relates to an easily-adhesive polyester film having excellent antistatic properties, particularly an easily-adhesive white polyester film.

[0002]

2. Description of the Related Art Aromatic polyester films are widely used for magnetic recording materials, printing materials, etc. However, static electricity is easily generated as a problem common to plastic films, and film forming processes, processing processes, and when using products, etc. However, there are drawbacks in that various problems occur, and the magnetic paint and printing ink have poor adhesion.

Thick white polyester films are used for magnetic cards such as telephone cards and prepaid cards. The manufacturing process, processing process, antistatic property of the final product, UV ink and magnetic paint are used. Adhesion is difficult, and application of a primer has been proposed.

Conventionally, as a method for improving the antistatic property and the adhesive property, there is known a method of forming a primer layer of a synthetic resin to which an antistatic agent is added in advance on the film surface. In this case, an anionic compound or a cationic compound is used as the antistatic agent,
It was difficult to satisfy both the antistatic property, especially the antistatic property and adhesiveness under low humidity.

Generally, a phosphoric acid type antistatic agent is excellent in antistatic property and is also excellent in a coating stretching method (in-line coating method) in which an unstretched or uniaxially stretched polyester film is coated as a coating solution, and then the film is stretched and heat treated. It is also possible to develop excellent conductivity and antistatic property.
It is disclosed in Japanese Patent Publication No. 55, Japanese Patent Publication No. 1-49114, and the like.
However, in these methods, the coating property is poor due to poor wettability of the phosphoric acid type antistatic agent to the polyester film, and a good coating appearance cannot be obtained without pretreatment such as corona discharge treatment. Was limited.

[0006]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, by combining a specific surfactant with a phosphate ester antistatic agent, a coating solution was obtained. It can be applied as a good, and has an excellent coating appearance, antistatic property and adhesiveness, and finds that a highly adhesive polyester film, particularly a white polyester film, which is extremely useful as a substrate for various applications, can be obtained, The present invention has been completed.

[0007]

Means for Solving the Problems That is, the present invention provides (1) a phosphate ester antistatic agent, (2) a surfactant having an HLB of 12 or less, and (3) an acrylic resin on at least one surface of an aromatic polyester film. An easily-adhesive polyester film having an easily-adhesive coating formed by using a coating agent containing a composition comprising at least one binder selected from a system copolymer and a polyester copolymer.

The aromatic polyester forming the film in the present invention is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Specific examples of such polyesters include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate), and polyethylene-2,6-naphthalene dicarboxylate. These copolymers and blends of these with a small proportion of other resins are also included. Among these, polyethylene terephthalate and polyethylene-2,6-naphthalene dicarboxylate are particularly preferable.

The aromatic polyester preferably contains a white pigment such as titanium oxide and / or barium sulfate. In addition, inorganic fillers such as silicon oxide, aluminum oxide, magnesium oxide, calcium carbonate, kaolin, talc, etc., organic fillers made of heat-resistant polymers such as crosslinked polystyrene resin, crosslinked acrylic resin, urea resin and melamine resin, polyethylene , Polypropylene, ethylene / propylene copolymer, other resins such as olefinic ionomers, antioxidants, ultraviolet absorbers, optical brighteners, and the like may be contained as required.

The white polyester film in the present invention contains 5 to 20% by weight of a white pigment such as titanium oxide or barium sulfate, and the surface glossiness thereof can be arbitrarily selected.

In the present invention, the polyester film, particularly the white polyester film, is preferably a biaxially stretched film, and the thickness of the white film is 20 μm or more, preferably 50 to 500 μm, particularly preferably 75 to 300 μm.
m. When the thickness is less than 20 μm, the film as a magnetic card substrate has a weak rigidity, which is not preferable. On the other hand, if the film is too thick, for example, exceeding 500 μm, the film-forming property tends to be poor.

In the present invention, the primer layer (easy-adhesive coating) provided on at least one side of the polyester film is (1) a phosphate ester antistatic agent, (2) HLB
Is applied to the required surface of the film and a coating agent containing a composition having a surfactant of 12 or less and (3) at least one binder selected from acrylic copolymers and polyester copolymers, and dried. It is formed.

Examples of the phosphoric acid ester salt-based antistatic agent (1) which constitutes the coating material in the present invention include conventionally known compounds. Among them, phosphoric acid ester salt-based low molecular weight compounds such as phosphorus are preferred. Acid alkyl ester sodium salt, phosphoric acid alkyl ester potassium salt, phosphoric acid aryl ester sodium salt, phosphoric acid aryl ester potassium salt, phosphoric acid dialkyl ester sodium salt, phosphoric acid dialkyl ester potassium salt, phosphoric acid diaryl ester sodium salt, phosphoric acid Diaryl ester potassium salt, sodium polyalkylene oxide phosphate,
Preferable examples thereof include potassium polyalkylene oxide phosphate, substituted phosphoric acid partial ester salt and the like. It is preferable to use one selected from these or a plurality of them in combination.

In the present invention, the surfactant (2) is HLB.
Is 12 or less. Here, HLB is Hy
Abbreviation for drophile-lipophile balance, it is a numerical representation of the balance of lipophilic and hydrophilic moieties in the surfactant molecule, and was proposed by Griffin of Atlas. Its value can be calculated by the following equation (I).

[0015]

[Equation 1]

The phosphoric acid ester salt antistatic agent (1) which constitutes the coating material in the present invention has a drawback that coating repellency is easily generated on the polyester film due to its high hydrophilicity, but the above-mentioned low When a HLB surfactant is used in combination, this hydrophilicity is relaxed and uniform coating becomes possible. HLB
When it exceeds 12, hydrophilicity becomes strong and cissing application spots occur.

As the surfactant having an HLB of 12 or less,
Examples include polyethylene oxide / polypropylene oxide block copolymers, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene monoalkylates, polyoxyethylene-fatty acid esters, sorbitan fatty acid esters, glycerin fatty acid esters. it can. These may optionally be combined with other surfactants having an HLB of 12 or higher.

The constituents of the acrylic copolymer used as the binder (3) in the present invention include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, sodium acrylate, ammonium acrylate,
2-hydroxyethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, sodium methacrylate, ammonium methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, acrylamide, methacrylamide,
Examples thereof include N-methylol acrylamide and N-methylol methacrylamide. These monomers can be used in combination with other unsaturated monomers such as styrene, vinyl acetate, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride and divinylbenzene. The acrylic copolymer (3) can also be used as a modified acrylic copolymer, for example, a block polymer or graft polymer obtained by modifying an acrylic copolymer with polyester, polyurethane, silicone, epoxy, phenol resin or the like.

The acid component forming the polyester copolymer used as the binder (3) in the present invention includes terephthalic acid, 2,6-naphthalenedicarboxylic acid,
Examples thereof include isophthalic acid, phthalic acid, phthalic anhydride, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, phenylindanedicarboxylic acid and dimer acid. Two or more kinds of these components can be used. Further, it is also possible to use a small proportion of unsaturated polybasic acids such as maleic acid, fumaric acid, itaconic acid and hydroxycarboxylic acids such as p-hydroxybenzoic acid and p- (β-hydroxyethoxy) benzoic acid together with these components. it can. The proportion of the unsaturated polybasic acid component or hydroxycarboxylic acid component is at most 10 mol%, preferably 5 mol% or less.

The polyol component forming the polyester copolymer is ethylene glycol, 1,4-
Butanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylylene glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, poly (ethylene oxide) glycol, poly (Tetramethylene oxide) glycol, and further ethylene oxide adduct and propylene oxide adduct of bisphenol A represented by the following formula

[0021]

Embedded image

[0022]

Embedded image

The following can be exemplified. These can use 2 or more types.

Among such polyol components, ethylene glycol, ethylene oxide adduct of bisphenol A and propylene oxide adduct, and 1,4-butanediol are preferable, and ethylene glycol is more preferable.
An ethylene oxide adduct or propylene oxide adduct of bisphenol A.

Further, in order to facilitate the aqueous liquefaction of the polyester copolymer, it is possible to copolymerize a small amount of a compound having a sulfonate group or a compound having a carboxylic acid group, which is preferable.

Examples of such sulfonate group-containing compounds include 5-Nasulfoisophthalic acid, 5-ammoniumsulfoisophthalic acid, 4-Nasulfoisophthalic acid, 4-methylammoniumsulfoisophthalic acid, 2-
Na sulfoisophthalic acid, 5-K sulfoisophthalic acid,
Examples thereof include alkali metal sulfonic acid salt compounds such as 4-K sulfoisophthalic acid, 2-K sulfoisophthalic acid, and Na sulfosuccinic acid, and amine sulfonate compounds.

Examples of the carboxylic acid group-containing compound include trimellitic anhydride, trimellitic acid, pyromellitic dianhydride, pyromellitic acid, trimesic acid, cyclobutanetetracarboxylic acid, dimethylolpropionic acid, and the like, or monoalkalis thereof. Examples thereof include metal salts.

The polyester copolymer can also be used as a modified polyester copolymer, for example, a block polymer or graft polymer obtained by modifying a polyester copolymer with acrylic, polyurethane, silicone, epoxy, phenol resin or the like.

In the present invention, a phosphate ester antistatic agent (1), a surfactant having an HLB of 12 or less (2), and at least one binder selected from an acrylic copolymer and a polyester copolymer. The ratio of the phosphoric acid ester salt-based antistatic agent (1) per composition consisting of (3) is 5 to 40.
%, Preferably 10 to 30% by weight. This ratio is 40
If it exceeds 5% by weight, the adhesion of the primer layer to the printing ink becomes insufficient, while if it is less than 5% by weight, the antistatic property becomes insufficient, which is not preferable. The proportion of the surfactant (2) is 1 to 20% by weight, preferably 3 to 15% by weight. If this proportion exceeds 20% by weight, the adhesion of the primer layer to the printing ink becomes insufficient, while if it is less than 1% by weight, the wettability of the coating material to the polyester film becomes insufficient, which is not preferable.

The primer coating agent in the present invention is preferably applied as an aqueous coating agent (using water as a medium), but it is also possible to apply it as an organic solvent.
Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene,
Examples thereof include methanol, ethanol, n-propanol, isopropanol and the like. These may be used alone or in combination of two or more.

In the present invention, as long as the object of the present invention is not impaired, the coating material includes, for example, an ultraviolet absorber, a pigment,
Defoaming agent, coatability improver, organic filler, inorganic filler,
Lubricants, antiblocking agents, melamine-based, urea-based,
Other additives such as guanamine-based, epoxy-based, aziridine-based, blocked isocyanate-based cross-linking agents and coupling agents can be added.

The solid content concentration of the coating material in the present invention is usually
It is at most 30% by weight, more preferably at most 20% by weight.

In the present invention, a (primer) coating agent containing the above-mentioned components is applied to at least one side of a polyester film, and a polyester film before completion of crystal orientation is preferable as the film.

As the polyester film before the completion of the crystal orientation, an unstretched film obtained by heat-melting an aromatic polyester to form a film as it is, orienting the unstretched film in either the longitudinal direction or the transverse direction. Uniaxially stretched film, those which have been stretched and oriented at a low ratio in the longitudinal and transverse directions (the biaxially stretched film before being finally reoriented in the longitudinal or transverse direction to complete the oriented crystallization), etc. It can be illustrated.

In particular, the coating agent is applied to the uniaxially stretched film,
It is preferable that the coating film is dried or not dried, and the uniaxially stretched film is stretched in a direction perpendicular to the above stretching direction and heat-treated to produce the film.

The coating can be carried out on one side only or on both sides depending on the intended use of the film.

As a method for applying the coating agent to the polyester film, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a microgravure coating method, a reverse coating method, a roll brush method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, or the like may be applied alone or in combination.

In the present invention, the polyester film may be subjected to corona discharge treatment before being applied with the above-mentioned coating agent, but this coating agent is not always necessary because the wettability to the polyester film is improved. Absent.

The coating amount is preferably 0.5 to 50 g, more preferably 3 to 30 g per 1 m ² of the running film. The thickness of the final dry coating film (coating) is preferably 0.01 to 1 μm,
More preferably, it is 0.02 to 0.6 μm. The thickness of the coating film
When it is less than 0.01 μm, sufficient antistatic property cannot be obtained, while when it exceeds 1 μm, the slip property is deteriorated, which is not preferable.

The magnetic recording layer in the present invention is not particularly limited.
However, the following are typical examples.
Wear. That is, as magnetic powder, for example, γ-Fe_TwoO_Three, C
rO _Two, Co-γ-Fe_TwoO_Three, Fe_ThreeO_Four, BaO ・ 6F
eO_Three, Using magnetic metal powder, etc., and as a binder
Are vinyl acetate, polyvinylidene chloride, PVC and other vinyl
Nyl resin, acrylic resin, acrylonitrile / butadier
Rubber resins such as copolymers, nitrocellulose, etc.
Fiber, epoxy resin, phenol resin, polyuree
Using a tan resin, etc., if necessary, a dispersant, a lubricant,
Stabilizer, antistatic agent such as carbon, plasticizer mixed
Things can be mentioned.

The printing ink layer in the present invention is not particularly limited, and examples thereof include conventionally known UV-curable printing ink, electron beam-curable ink, and heat-sensitive recording ink.

[0042]

EXAMPLES The present invention will be further described below with reference to examples. The characteristics in the examples were obtained by the following method.

1. Appearance of application of primer-coated film The appearance of application of the primer-coated film is visually determined.も の indicates that the coating surface is uniform and has no defect, and X indicates that the coating surface has spots and repelling defects.

2. Adhesive strength of magnetic paint The following evaluation paint was applied to the sample film with a Meyer bar so that the thickness after drying would be about 4 μm, and the film was dried at 100 ° C for 3 days.
Dry for minutes. After that, it was aged at 60 ° C for 24 hours, and then a Scotch tape No. 600 (3M) with a width of 12.7 mm and a length of 15 cm was adhered to it so that no bubbles could enter it.
Using a manual load roll described in SC2701 (1975), the film is leveled and brought into close contact and cut into a tape width. The strength when peeled 180 degrees is measured.

[Evaluation paint] 25 parts by weight of urethane resin Nipporan 2304 (made by Nippon Polyurethane), 50 parts by weight of vinyl chloride / vinyl acetate resin S-REC A (made by Sekisui Chemical Co., Ltd.), dispersant Recion P (made by Riken Vitamin) ) 1 part by weight and magnetic agent CTX-860 (manufactured by Toda Kagaku) 500
Part by weight is dissolved in a mixed solvent of methyl ethyl ketone / toluene / cyclohexanone to prepare a 40% solution, which is then dispersed in a sand grinder for 2 hours. Then the crosslinking agent Coronate L
Add 25 parts by weight (as solid content) and stir well to obtain a magnetic paint.

3. Adhesive strength of UV ink A UV curable printing ink (Flash Dry FD Carton P Hongro made by Toyo Ink) is RI on the sample film.
After printing with a tester (manufactured by Akira Seisakusho Co., Ltd.), a UV ink layer having a thickness of 4 μm is formed by curing with a medium pressure mercury lamp (80 W / cm, one lamp type; manufactured by Nippon Battery) UV curing device. Cellophane tape (18 mm width; made by Nichiban) was pasted on the UV ink layer to a length of 15 cm, and a fixed load was applied with a 2 kg manual load roll, and the film was fixed to one end of the cellophane tape at 90 °. The adhesive strength is evaluated by peeling in the direction. The adhesive strength is evaluated according to the following 5 grades.

5: Ink layer does not peel at all 4: Ink layer of less than 3% peels off 3: 3 to 10% of ink layer peels off 2:10 to 30% of ink layer peels off 1: 30% 3. The above ink layer peels off. Antistatic properties

The antistatic property was evaluated by the surface specific resistance of the sample film. As the specific surface resistance, a specific resistance measuring instrument manufactured by Takeda Riken Co., Ltd. was used.
% And 45%, the surface specific resistance value (Ω / □) after 1 minute at an applied voltage of 500 V is measured. 1 × 10 ¹¹ Ω / □ or less is preferable.

[Example 1] Solid content concentration 10 of an acrylic copolymer (number average molecular weight: 253000) made from methyl methacrylate, ethyl acrylate, 2-hydroxyethyl methacrylate and N-methylol methacrylamide.
% Aqueous dispersion to prepare an aqueous liquid A.

On the other hand, a composition comprising 90% by weight of polyester (intrinsic viscosity 0.63) made from terephthalic acid and ethylene glycol and 10% by weight of titanium oxide was melt extruded on a rotary cooling drum maintained at 20 ° C. to obtain an unstretched film. Then, after stretching 3.6 times in the machine axis direction, 70% by weight of the above aqueous liquid A and 20% by weight of an aqueous solution of dioctyl phosphate sodium salt as an antistatic agent (concentration 10% by weight) and a surfactant An aqueous solution of polyoxyethylene nonyl ether (HLB = 11.5) (concentration 10% by weight)
A primer coating composed of 10% by weight of 4 g / m ² (w
The amount of et) was applied to both sides of the film by the kiss coat method. Subsequently, the film was stretched 3.9 times in the transverse direction to obtain a primer-coated biaxially stretched polyester film having a thickness of 188 μm.

Table 1 shows the coating appearance of the treated surface of this film, the adhesiveness of the magnetic paint, the adhesive strength of the UV ink and the antistatic property.
Are shown together.

Example 2 Copolyester (Tg) having an intrinsic viscosity of 0.53 prepared from terephthalic acid, isophthalic acid, 5-Nasulfoisophthalic acid, ethylene glycol and a propylene oxide adduct of bisphenol A represented by the following structural formula. = 76 ° C.), an aqueous dispersion having a solid content concentration of 10% was prepared to obtain an aqueous liquid B.

[0053]

Embedded image

The aqueous liquid A used in Example 1 was replaced with the above aqueous liquid B.
The same coating composition ratio as in Example 1 except that
An amount of g / m ² (wet) was applied to both sides of the film to obtain a primer-coated biaxially oriented polyester film.

The coating appearance of the treated surface of this film, the adhesiveness of the magnetic paint, the adhesive strength of the UV ink and the antistatic property are shown in Table 1.
Are shown together.

[Example 3] The coating composition used in Example 1 was 40% by weight of an aqueous liquid A, 30% by weight of an aqueous liquid B, and an aqueous solution of potassium dipentyl ester phosphate as an antistatic agent (concentration: 10% by weight). ) 20 wt% and polyoxyethylene nonylphenyl ether (HLB = 1) which is a surfactant.
0.9) An aqueous solution (concentration 10% by weight) 10% by weight was used, except that the coating composition ratio was exactly the same as in Example 1 except that the amount of 4 g / m ² (wet) was applied to both sides of the film. To obtain a primer-coated biaxially stretched polyester film.

Table 1 shows the coating appearance of the treated surface of this film, the adhesiveness of the magnetic paint, the adhesive strength of the UV ink and the antistatic property.
Are shown together.

Comparative Example 1 The surfactant used in Example 1 was polyoxyethylene nonylphenyl ether (HLB).
= 14.0) except that the coating composition ratio was exactly the same as in Example 1 except that 4 g / m ² (wet) was applied to both sides of the film to obtain a primer-coated biaxially stretched polyester film.

Table 1 shows the coating appearance of the treated surface of this film, the adhesiveness of magnetic paint, the adhesive strength of UV ink and the antistatic property.
Are shown together.

Comparative Example 2 The coating composition used in Example 1 was 50% by weight of aqueous liquid A, and an aqueous solution of potassium dipentyl ester phosphate as an antistatic agent (concentration 10% by weight) 4
The same coating as in Example 1 except that the coating agent was changed to 0% by weight and 10% by weight of an aqueous solution (concentration 10% by weight) of polyoxyethylene nonylphenyl ether (HLB = 10.9) as a surfactant. 4g / m ² (we
The amount of t) was applied on both sides of the film to obtain a primer-coated biaxially oriented polyester film.

The coating appearance of the treated surface of this film, the adhesiveness of the magnetic paint, the adhesive strength of the UV ink and the antistatic property are shown in Table 1.
Are shown together.

Comparative Example 3 Example 1 was repeated except that the antistatic agent used in Example 1 was changed to sodium dodecyl sulfonate.
A primer-coated biaxially stretched polyester film was obtained by applying an amount of 4 g / m ² (wet) on both sides of the film in the same coating composition ratio as in.

Table 1 shows the coating appearance of the treated surface of this film, the adhesiveness of the magnetic paint, the adhesive strength of the UV ink and the antistatic property.
Are shown together.

[Comparative Example 4] Table 1 shows the adhesion of the magnetic coating, the adhesion of the UV ink, and the antistatic property on the surface of the biaxially stretched polyester film obtained in Example 1 without the primer coating. .

[0065]

[Table 1]

[0066]

The easily-adhesive polyester film according to the present invention is particularly excellent in coating appearance, adhesive strength and antistatic property as compared with the conventional ones. For example, magnetic cards, magnetic disks, printing materials, graphic materials, It is useful as a photosensitive material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B32B 27/18 B32B 27/18 D 27/30 27/30 A 27/36 27/36 C09D 167 / 02 PKX C09D 167/02 PKX // B29K 67:00 B29L 9:00 C08L 67:03

Claims (6)

[Claims] 1. An (1) phosphoric acid ester salt-based antistatic agent and (2) HL on at least one side of an aromatic polyester film.
Applying an antistatic easy-adhesive coating using a coating agent containing a composition having a B of 12 or less and (3) at least one binder selected from (3) acrylic copolymers and polyester copolymers. Made easy-adhesive polyester film. 2. The easily adhesive polyester film according to claim 1, wherein the aromatic polyester film is a white film containing a white pigment and having a thickness of 20 μm or more. 3. The easily adhesive polyester film according to claim 1, wherein the coating agent is an aqueous coating agent. 4. A phosphoric acid ester salt-based antistatic agent,
The proportions of (2) surfactant and (3) binder are 5 to 40% by weight, 1 to 20% by weight and 94 to 100% by weight based on the total amount of these.
The easily adhesive polyester film according to claim 1, which is 40% by weight. 5. The easily-adhesive polyester film according to claim 1, wherein the easily-adhesive coating film has a thickness of 01 to 1 μm. 6. A laminated film provided with a magnetic recording layer and / or a printing ink layer on at least a part of the easily adhesive coating of the easily adhesive polyester film according to claim 2.