JPH11157034A - Polyester film with antistatic property and blocking resistivity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an antistatic property, and prevent the occurrence of blocking by forming a skin film consisting of the specific quantity and specific structure of a mixture of an antistatic agent, and the specific quantity of melamin setting epoxy resin and/or acryl and melamin thermoplastic resin on a polyester film. SOLUTION: A skin film is formed on a polyester film, which consists of a mixture of a 30-75 wt.% cathionic interfacial active agent (an antistatic agent) consisting mainly of a quaternary ammonium salt indicated by formula (in the formula, R is an alkyl group having a carbon number of 8 or more, R<1> is a lower alkyl group, and R<2> is a lower alkylene group), and 70-25 wt.% melamin setting epoxy resin and/or acrylic/melamin thermosetting resin. Also, a surface hardness of the film surface provided with the skin film is made in a pencil hardness of H-3H. Accordingly, this can not only prevent the adhesion of dirt and dust and charge fault of spark and the like, but also preclude the occurrence of blocking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyester film having antistatic properties and blocking resistance.

[0002]

2. Description of the Related Art Biaxially stretched polyester films represented by polyethylene terephthalate film have excellent properties such as transparency, dimensional stability, mechanical properties, electrical properties, and chemical resistance, and are used in various industrial fields. Have been.

[0003] Polyester films have the above-mentioned excellent properties, but since the polyester resin itself has high electrical insulation properties, it is very easy to be charged and various problems occur due to generation of static electricity. .

Therefore, conventionally, when a film is produced, a metal powder, a tin oxide / antimony-based conductive agent, an anionic surfactant, a polystyrene sulfonic acid, etc. are kneaded into a resin to be melt-molded, or a surface active film is formed on the film surface. It has been practiced to apply an antistatic agent mainly composed of an agent.

However, in the method of kneading the antistatic agent into the resin, although the antistatic property can be obtained, there is a problem that the transparency of the film is lowered. In addition, in such a kneading method, the antistatic agent bleeds out to the surface of the film to exhibit its effect, but when the amount of bleedout is small, the antistatic effect is insufficient, while the amount of bleedout is reduced. In many cases, there has been a problem in that the suitability for various coating processes on the film surface is reduced and blocking between the films is caused.

On the other hand, a method of applying an antistatic agent to a film surface not only can surely impart a desired antistatic property, but also can easily control the performance level. Has been adopted.

However, this method also has a problem in the durability of the antistatic agent film provided on the film surface, and the antistatic agent falls off due to repeated friction and washing with water, and set-off and blocking of the antistatic agent are problematic. Has become.

For example, when a film coated with an antistatic agent is used as thermal transfer paper, a release layer, a transfer ink layer, and an adhesive layer are sequentially provided on the opposite side of the antistatic agent film. Offset tends to cause a decrease in adhesion between the release layer and the film and a blocking between the antistatic agent film and the adhesive.

In order to solve such problems, attempts have been made to increase the adhesion between the antistatic agent and the film and to improve the surface hardness of the antistatic agent film.

For example, there is a method of applying a polymer type cross-linking antistatic agent, but the scratch resistance is still poor, and a sufficient improvement effect has not been obtained. Also,
After applying the antistatic agent, there is a method in which a hard coat treatment is further performed on the applied surface. However, not only the number of processing steps increases, but also since the antistatic agent is not substantially present on the film surface, a sufficient antistatic effect is obtained. It is difficult to get.

If the antistatic agent can be uniformly dispersed in a hard coat agent based on a thermosetting resin,
Since there is no loss in the process and the antistatic agent is present on the film surface, both effects of the antistatic effect and the antiblocking effect can be expected, but such a surface treatment agent has not been found. .

[0012]

SUMMARY OF THE INVENTION In view of such circumstances, an object of the present invention is to provide a polyester film which is excellent in antistatic properties, does not cause blocking, and has good scratch resistance.

[0013]

Means for Solving the Problems The present inventors have made intensive studies to solve this problem, and as a result, have found that an antistatic agent having a specific structure and a melamine-cured epoxy resin and / or acryl /
A mixed solution composed of a melamine-based thermosetting resin solution is uniformly compatible with each other, and this mixed solution is applied to a polyester film, and it is found that the above object is achieved by drying and curing. .

That is, the gist of the present invention is to provide a polyester film containing 30 to 75% by weight of a cationic surfactant (antistatic agent) containing a quaternary ammonium salt represented by the following structural formula as a main component: Melamine cured epoxy resin and / or
Or an antistatic and anti-blocking polyester film provided with a coating comprising a mixture of 70 to 25% by weight of an acrylic / melamine-based thermosetting resin.

[0015]

Embedded image (Here, R represents an alkyl group having 8 or more carbon atoms, R ¹ represents a lower alkyl group, and R ² represents a lower alkylene group.)

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, the polyester forming the film is formed by the polymerization of an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid or naphthalenedicarboxylic acid with a diol such as ethylene glycol, propylene glycol or 1,4-butanediol. Polyester obtained by condensation, especially polyethylene terephthalate (PE) obtained by polycondensation of terephthalic acid and ethylene glycol
T) is preferred.

The antistatic agent used in the present invention comprises:
Cationic surfactants containing a quaternary ammonium salt represented by the above structural formula as a main component, and particularly preferred are those represented by the following structural formula.

Embedded image

The polyester film of the present invention comprises an antistatic agent comprising a cationic surfactant containing a quaternary ammonium salt as a main component, a melamine-cured epoxy resin and / or
Alternatively, a film made of a mixture of an acrylic / melamine-based thermosetting resin is provided.

The proportion of the antistatic agent and the thermosetting resin constituting the film is 30 to 75% by weight (preferably 45% by weight).
To 65% by weight) and 70 to 25% by weight (preferably 55 to 35% by weight) of the thermosetting resin. If the proportion of the antistatic agent is smaller than this, the antistatic effect becomes insufficient, while if the proportion of the antistatic agent is too large, the curing reaction of the thermosetting resin is inhibited, and the adhesion between the polyester film and the film and The surface hardness of the film is undesirably reduced.

In the present invention, it is necessary that the antistatic agent and the thermosetting resin are dispersed as uniformly as possible.
If the dispersion is insufficient, sufficient performance cannot be obtained for both the antistatic effect and the antiblocking effect.

The melamine-cured epoxy resin and acrylic / melamine resin used in the present invention satisfy this requirement.

Specific examples of the thermosetting resin include SF-409, SF-413, SF-910H, and A-DA manufactured by Dainippon Ink and Chemicals, Inc.
-911, A-914, A-915 and EX 1 manufactured by Dainichi Seika Kogyo Co., Ltd.
14 D media and the like.

The amount of the film is 0.3 to 1.
Suitably, it is 5 g / m ² , preferably 0.7 to 1.2 g / m ² . If this amount is too small, sufficient antistatic performance cannot be obtained, while if this amount is too large, drying and drying
It takes a long time for the curing reaction to result in poor productivity, and in addition, the polyester film may curl toward the coated surface, which is not preferable.

The polyester film of the present invention can be obtained by applying a mixed solution of an antistatic agent and a thermosetting resin to at least one surface of the polyester film, heating and drying and curing.

As the coating method, known methods such as a gravure roll method, a spray method, a roll coater method, a reverse roll coating method and the like can be used, but the gravure roll method is suitable because the coating amount can be easily adjusted.

The conditions for the drying / curing reaction of the film are suitably at a temperature of 100 to 200 ° C., preferably 150 to 180 ° C., for 5 to 30 seconds, preferably 10 to 20 seconds. It is desirable to select conditions so that the composition is cured and the properties are sufficiently exhibited. If this temperature is too low, the curing reaction of the resin does not proceed sufficiently, while if this temperature is too high, wrinkles due to heat loss of the polyester film may be generated strongly.

Before applying the mixed solution of the antistatic agent and the thermosetting resin, it is preferable that a physical or chemical treatment for improving the adhesiveness between the polyester film and the film is previously performed on the polyester film. If necessary, a curing catalyst such as an organic acid can be added to the coating solution within a range that does not impair the properties of the film.

The coating film is formed so as to obtain an antistatic performance such that the surface specific resistance value of the film surface on which the film is provided is 10 ⁸ to 10 ¹¹ Ω / □ and the ash adhesion height in the ash test is 0 mm. It is desirable to select a composition, a coating amount, and the like.

Further, it is desirable that the surface hardness of the surface of the film on which the coating is provided is H to 3H in pencil hardness. When the pencil hardness is lower than H, the scratch resistance becomes poor, and the blocking between the films occurs when printing is performed with various inks on the opposite side of the coating or when the roll coated with the hot melt adhesive is rewound. It is easy to occur.

[0031] The polyester film of the present invention comprises:
After applying various primers and inks to the opposite side where the film is provided to not only prevent the adhesion failure of dust and sparks, but also to provide excellent scratch resistance,
Even in the case of winding in a roll shape, there is no fear of blocking, and it can be suitably used as various process papers such as release paper and thermal transfer paper.

For example, the polyester film of the present invention is used as thermal transfer paper in a film configuration as shown in FIG. In FIG. 1, a film 2 for imparting antistatic properties is provided on one surface of a polyester film 1, and a release layer 3, an ink layer 4, and a hot-melt adhesive layer 5 are sequentially coated on the opposite surface. I have. The film of FIG.
It is used by being thermally transferred onto a transfer substrate via a hot melt adhesive. As the hot melt-based adhesive, a polyester-based resin or a polyolefin-based resin mainly containing an ethylene-vinyl acetate copolymer is used.

[0033]

Next, the present invention will be described specifically with reference to examples. In addition, the raw materials and evaluation methods used in the examples are as follows. 1. Raw materials ・ Antistatic agent “Hobolux DM” manufactured by Nichika Chemical Industry Co., Ltd.
Cationic surfactant liquid containing quaternary ammonium salt as a main component, which is an alkyl group of 12 (solids concentration: 45% by weight)-Thermosetting resin "EX114D Medium" Acrylic / Melamine-based thermosetting resin liquid (solid content: 75% by weight) ・ Polyester film “Emblet” made by Unitika, biaxially stretched PET film (thickness: 25 μm) ・ Hot melt adhesive “Elitel UE-3800” made by Unitika Polyester hot melt adhesive (solids concentration 35% by weight)

2. Evaluation method (a) Adhesion of the film The cellophane tape (Nichiban,
Elpack LP-24) was pressed, and the cellophane tape was vigorously peeled off in the 180 ° direction (positive cellophane tape peeling). The degree of the adhesive strength of the cellophane tape was evaluated according to the following three grades. ：: Adhesive strength is maintained. Δ: Adhesion was partially impaired. X: The adhesive strength is completely impaired. (b) Blocking resistance A piece of film having a size of 7 cm x 7 cm was sampled, and then 15
The sheets were stacked and pressed under a load of 10 kg at a temperature of 40 ° C. for 24 hours, and evaluated according to the following three grades depending on the degree of blocking. ：: There is no blocking, and there is no catch when peeling. Δ: Slightly caught or a little sound was heard when peeling. ×: Strongly caught when peeled, damage is observed on the film surface. (c) Pencil hardness (scratch resistance) Measured according to JIS K 5400. (d) Surface resistivity According to ASTM D 257, a high resistance meter (Hiresta manufactured by Mitsubishi Yuka Co., Ltd.)
MCP-Tester HT-210). (e) Ash adhesion height (ash test) After rubbing a 200mm x 25mm test specimen humidified at 23 ° C and 50% RH with a cotton cloth reciprocating 20 times, the test specimen was quickly rubbed.
Take the tobacco ash dried at 60 ° C. for 2 hours, gradually lower the test piece until the ash adheres to the test piece, and read the height at which the ash is observed in 5 mm units on a scale. .

Examples 1 to 5 A thermosetting resin "EX 114 D Medium" was diluted with a mixed solvent of methyl ethyl ketone / toluene to prepare a resin solution A having a solid content of 35%. An antistatic agent “Hobolux DM” was added to this resin liquid A and the coating liquid composition (antistatic agent AS
/ Resin solids weight ratio), and sufficiently stirred at room temperature to obtain a uniform coating solution B. The coating amount shown in Table 1 (amount after drying and curing) was applied to one side of the polyester film "Emblet" by the gravure roll method.
And dried and cured at 180 ° C. for 20 seconds to obtain an antistatic polyester film. Table 1 shows the results of evaluating the characteristics of the obtained film.

Comparative Example 1 The resin solution A in Example 1 was applied to one surface of a polyester film “Emblet” by a gravure roll method so as to have a coating amount (amount after drying and curing) shown in Table 1.
The polyester film was dried and cured at 80 ° C. for 20 seconds to obtain a polyester film provided with a thermosetting resin film. Table 1 shows the results of evaluating the characteristics of the obtained film.

COMPARATIVE EXAMPLE 2 A coating solution having an antistatic agent "Hobolux DM" diluted with methanol to a solid content of 3.5% by weight was applied to one surface of a polyester film "Emblet" by a gravure roll method to obtain a coating amount of 0.2. g / m ² , 1
It was dried at 40 ° C. for 20 seconds to obtain an antistatic polyester film. Table 1 shows the results of evaluating the characteristics of the obtained film.

Comparative Examples 3 to 5 Polyester films provided with coatings were obtained in the same manner as in Example 1 except that the composition of the coating solution was changed as shown in Table 1. Table 1 shows the results of evaluating the characteristics of the obtained film.

[0039]

[Table 1]

REFERENCE EXAMPLES 1 AND 2 On the side opposite to the surface of the polyester film obtained in Examples 3 and 5 where the film is provided, a hot-melt adhesive "Elitel UE-3800", solid content concentration 35% by weight ) Was applied so that the solid content was 2 g / m ^2, and cooled. When the blocking resistance of the obtained films was evaluated, all were good (良好).

COMPARATIVE REFERENCE EXAMPLES 1 AND 2 On the opposite side of the polyester film obtained in Comparative Examples 4 and 5 on which the film is provided, a hot-melt adhesive “Elitel UE-3800” was added with a solid content of The coating was performed so as to be ² g / m ² and cooled. When the blocking resistance of the obtained films was evaluated, all were poor (x).

[0042]

According to the present invention, there is provided a polyester film which is excellent in antistatic properties, free from blocking, and has good scratch resistance. And this polyester film can be used suitably as various process papers, such as release paper and thermal transfer paper.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a film configuration when a polyester film of the present invention is used as thermal transfer paper.

[Explanation of symbols]

 1 polyester film 2 coating 3 release layer 4 ink layer 5 hot melt adhesive layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 5/19 C08K 5/19 C08L 67/02 C08L 67/02 C09D 5/00 C09D 5/00 P 133/04 133/04 161 / 28 161/28 163/00 163/00 (72) Inventor Chiemi Nishitani 31-3 Uji Hinojiri, Uji City, Kyoto Unitika Inside Uji Plastic Factory (72) Inventor Tomoko Yamanaka Uji Hino, Uji City, Kyoto Prefecture Bottom 31-3 Unitika Inside Uji Plastic Factory

Claims (4)

[Claims] 1. A polyester film comprising 30 to 75% by weight of a cationic surfactant (antistatic agent) containing a quaternary ammonium salt represented by the following structural formula as a main component, a melamine-cured epoxy resin and / or Alternatively, an antistatic and anti-blocking polyester film provided with a film comprising a mixture of 70 to 25% by weight of an acrylic / melamine-based thermosetting resin. Embedded image (Here, R represents an alkyl group having 8 or more carbon atoms, R ¹ represents a lower alkyl group, and R ² represents a lower alkylene group.) 2. The polyester film according to claim 1, wherein the amount of the coating is in the range of 0.3 to 1.5 g / m ² . 3. The polyester film according to claim 1, wherein the surface of the film provided with the coating has a surface resistivity of 10 ⁸ to 10 ¹¹ Ω / □ and an ash adhesion height in an ash test of 0 mm. 4. The polyester film according to claim 1, wherein the surface of the film provided with the coating has a pencil hardness of H to 3H.