JPH10265594A - Antistatic polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject film without generating static electricity in a process such as coating or printing processing by forming a primer layer comprising a specific cationic surfactant and a specified copolyester on at least one surface of a polyester film. SOLUTION: This antistatic polyester film is obtained by forming a primer layer comprising 5-40 wt.% cationic surfactant consisting essentially of a quaternary ammonium salt represented by the formula (R is a >=8C alkyl) and 95-60 wt.% copolyester comprising an aromatic dicarboxylic acid containing 20-95 mol% terephthalic acid component and an aliphatic glycol in preferably 0.01-0.2 g/m<2> coating weight. The resultant film has 10<9> -10<12> Ω surface resistivity and is excellent in adhesion to inks or coating materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an antistatic polyester film, and more specifically, to an antistatic polyester film.
The present invention relates to an antistatic polyester film having no trouble due to generation of static electricity in processes such as coating and printing, and having excellent adhesion to various inks and paints.

[0002]

2. Description of the Related Art Biaxially stretched polyester films represented by polyethylene terephthalate have excellent properties such as transparency, dimensional stability, mechanical properties, electrical properties, and chemical resistance, and are used in various industrial fields. ing. Polyester film has the above excellent properties,
Since the polyester resin itself has high electrical insulation properties, it is extremely easily charged, and causes various problems due to generation of static electricity.

[0003] Therefore, conventionally, metal powder, tin oxide,
A method of kneading an antimony-based conductive agent, an anionic surfactant, polystyrene sulfonic acid, or the like, or applying it to the film surface has been adopted. However, the method of kneading a metal powder or a tin oxide / antimony-based conductive agent into a resin has a problem that the antistatic property is excellent but the transparency of the film is reduced, and the anionic surfactant is added to the resin. In the kneading method, there is a problem that the surfactant bleeds out to the surface of the film and clouding occurs on the surface, thereby lowering the transparency. In addition, in the method of applying an antistatic agent, when the film is treated with various coating agents or when the printing process is performed, the adhesiveness to ink or paint is reduced. Even when the primer layer was applied, the adhesion was still insufficient. In order to improve the adhesion of the antistatic agent to the film, corona treatment, plasma treatment, E
A method of performing physical treatment such as B treatment or a chemical treatment using an alkaline aqueous solution or an amine aqueous solution is known. However, practical methods such as deterioration of antistatic property with time and contamination of a working environment due to volatilization of the chemical are known. There was a problem.

[0004]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and is excellent in transparency, low in surface specific resistance value, free from electrostatic interference, and applied in a secondary processing step of a polyester film. It is an object of the present invention to provide an antistatic polyester film having excellent adhesiveness to various printing inks and paints such as gravure ink, offset ink, and ultraviolet curing ink (UV ink).

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve such problems, and as a result, a primer layer obtained by blending a specific antistatic agent with a copolymerized polyester resin having a specific structure. The present inventors have found that an antistatic polyester film having excellent antistatic properties and excellent adhesiveness to various printing inks and the like can be obtained by providing the same, thereby achieving the present invention.

That is, the gist of the present invention is as follows. On at least one side of the polyester film, 5 to 40% by weight of a cationic surfactant mainly composed of a quaternary ammonium salt represented by Chemical Formula 1 and 20 to 20% of a terephthalic acid component
An antistatic polyester film provided with a primer layer comprising 95 to 60% by weight of a copolymerized polyester comprising an aromatic dicarboxylic acid containing 95 mol% and an aliphatic glycol.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The polyester film used in the present invention is obtained by polycondensation of an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid with a diol such as ethylene glycol, propylene glycol, and 1,4-butanediol. It is a film using polyester as a raw material, and polyethylene terephthalate (PET) obtained by polycondensation of terephthalic acid and ethylene glycol is particularly preferable.

The antistatic agent used in the present invention comprises:
It is a cationic surfactant containing a quaternary ammonium salt represented by Chemical Formula 1 as a main component.

The above antistatic agent has good compatibility with the copolymerized polyester resin forming the primer layer together with the antistatic agent in the present invention, so that an excellent antistatic effect is obtained and the transparency of the film is maintained. be able to.

As the dicarboxylic acid component of the copolymerized polyester forming the primer layer in the present invention, it is necessary that 80 mol%, preferably 90 to 100 mol%, is an aromatic dicarboxylic acid. The proportion of aromatic dicarboxylic acid is 80
When the amount is less than mol%, the glass transition point (Tg) of the copolymerized polyester becomes low, so that heat resistance and blocking resistance are lowered, and troubles in the secondary processing step are likely to occur, which is not preferable.

The aromatic dicarboxylic acid in the present invention must contain terephthalic acid in an amount of 20 to 95 mol%, preferably 30 to 90 mol%. Further, as aromatic dicarboxylic acids other than terephthalic acid, isophthalic acid,
Examples thereof include phthalic acid and naphthalenedicarboxylic acid, and a mixture thereof. Isophthalic acid is particularly preferred. When the proportion of terephthalic acid exceeds 95 mol%, the solubility of the obtained copolymerized polyester in organic solvents such as toluene and methyl ethyl ketone is reduced, so that coating processing becomes difficult, and the copolymerized polyester coating film tends to become brittle. Not preferred. In addition, the proportion of terephthalic acid is 20
When it is less than mol%, the T of the resulting copolymerized polyester is
g decreases, and heat resistance and blocking resistance decrease.

The dicarboxylic acid component in the present invention may contain 20 mol% or less of one or more aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid and sebacic acid.

The glycol component of the copolymerized polyester in the present invention includes ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,2-butanediol, 1,4-butanediol, 1,
Examples thereof include 2-pentanediol, 1,5-pentanediol, 1,4-hexanediol, 1,6-hexanediol, diethylene glycol, and the like, and these may include two or more kinds.

The method for producing the copolymerized polyester in the present invention is not particularly limited, and a known method can be used. For example, a method in which an alkyl ester of an aromatic dicarboxylic acid and, if necessary, an alkyl ester of an aliphatic dicarboxylic acid and an aliphatic diol are subjected to transesterification simultaneously or in a stepwise manner, followed by polymerization. At the time of these reactions, any known various catalysts, stabilizers, modifiers or additives may be added.

In the present invention, the constituent ratio of the solid content of the antistatic agent and the solid content of the copolymerized polyester in the primer layer is 5 to 40/95 to 60 (% by weight), more preferably 10 to 30.
/ 90-70 (% by weight). If the amount of the antistatic agent is less than 5% by weight, the antistatic effect is insufficient. If the amount is more than 40% by weight, the adhesion to the substrate polyester film is reduced, or the printing ink in the secondary processing step is not used. Adhesion with the like decreases.

The coating amount of the primer layer after drying is as follows:
It is 0.01 to 0.2 g / m ² , more preferably 0.02 to 0.1 g / m ² . When the coating amount is less than 0.01 g / m ² , the antistatic property and the adhesiveness to printing ink and the like are reduced, and when the coating amount is more than 0.2 g / m ² , the transparency is undesirably reduced.

As a method of applying a primer layer to a polyester film, a solution obtained by dissolving a surfactant and a copolymerized polyester in a solvent such as ethyl acetate, methanol, toluene, methyl ethyl ketone is prepared by a gravure roll method, a spray method, or a roll coater method. For example, a gravure roll method is suitable for adjusting the amount of application. Drying conditions after coating are as follows: temperature: 100 to 180 ° C, preferably 120 to 140 ° C.
The condition of 5 to 30 seconds is appropriate. Further, it is desirable that the polyester film has been previously subjected to a physical treatment such as a corona treatment or a chemical treatment in order to improve the adhesion to the primer layer.

[0018]

Next, the present invention will be described more specifically with reference to examples. The measuring method of each property of the raw material and the film used is as follows.

(1) Raw materials Cationic surfactant (antistatic agent): Hobolux DM (manufactured by Nikka Chemical Co., Ltd.)
(Cationic surfactant mainly composed of a quaternary ammonium salt which is an alkyl group of 12; solid content concentration: 33% by weight) ・ Sulfonic acid type anionic surfactant: “Chemistat 3033” manufactured by Sanyo Chemical Industries, Ltd. ・ Curing Agent: "Coronate H" manufactured by Nippon Polyurethane Industry Co., Ltd.
L "(solids concentration: 75% by weight)-Copolyester resin (A): The acid component is terephthalic acid 46 mol%, isophthalic acid 46 mol%, adipic acid 8 mol%, and the glycol component is ethylene glycol 50 mol. %, Neopentyl glycol 50 mol% (Tg 45 ° C). -Copolyester resin (B): The acid component is 30 mol% of terephthalic acid, 30 mol% of isophthalic acid, and 40 mol% of adipic acid, and the glycol component is composed of 25 mol% of ethylene glycol and 75 mol% of neopentyl glycol. Copolyester resin (Tg 3 ° C). -Biaxially stretched PET film: "Emblet 50μm" manufactured by Unitika

(2) Measurement method a) Tg (° C.) Tg of the copolymerized polyester forming the primer layer was measured with a differential scanning calorimeter (DSC-50, manufactured by Shimadzu Corporation). B) Stability of the coating liquid The state of the coating liquid applied to the polyester film was visually observed, and the degree of stability was evaluated based on the following criteria. ：: The solution was transparent and stable. Δ: The liquid was uniformly dispersed, but the solution was opaque. X: The antistatic agent aggregated and precipitated or gelled. C) Adhesion of coating film A polyester layer coated with a primer layer and dried is coated with a cellophane tape (Nichiban, ELPACK LP-24).
) Was pressure-bonded and the cellophane tape was vigorously peeled off in the 180 ° direction (forward cellophane tape peeling). ：: The adhesive strength of the cellophane tape is maintained. Δ: The adhesive strength of the cellophane tape was partially impaired. ×: The adhesive strength of the cellophane tape is completely impaired. D) Blocking resistance The polyester film coated with the primer layer and dried is cut into a square of 10 cm × 10 cm, and 15 pieces of the
The blocking property after pressurizing at 10 ° C. for 24 hours at 24 ° C. was evaluated according to the following criteria. ：: There is no blocking and there is no catch when peeling. Δ: Slightly caught when peeled (adhesive force slightly applied). ×: Strongly caught when peeled, damage is seen on the surface of the primer layer. E) Cloudiness of film Measured using a haze meter (TC-H3DPK, manufactured by Tokyo Denshoku Co., Ltd.).

(F) Adhesion of UV-curable ink A UV-curable ink is applied to a polyester film coated with a primer layer and dried to a thickness of about 3 μm after drying with an RI tester. And UV irradiation with an ultraviolet irradiation apparatus (HB-80101BY), followed by drying at room temperature for 24 hours or more. As the ultraviolet curable ink, Flash Dry FDS-2 (Red) (manufactured by Toyo Ink Mfg. Co., Ltd.) was mixed with a FD reducer (manufactured by Toyo Ink Mfg. Co., Ltd.) as a diluent. (1) Cross-cut cellophane tape peeling test Cut 100 mm squares by making cuts at 1 mm intervals on the 10 mm × 10 mm square ink coated surface, making 100 cellophane tape peeling, and remaining without peeling Check the number of squares,
Five-step evaluation was performed according to the following evaluation criteria. 1. 1. Less than 10 remaining eyes 2. More than 10 eyes and less than 50 eyes left. 3. Leave more than 50 eyes and less than 90 eyes. 4. The number of remaining eyes is 90 or more and less than 95. The number of remaining eyes is 95 or more. (2) Scratch (scratch) property The ink-applied surface was easily scratched several times back and forth with a fingernail, and the surface condition at that time was examined and evaluated according to the following evaluation criteria. ：: The scratched portion is not peeled off at all. Δ: Part of the scratched part peeled off. ×: The scratched portion is completely peeled off. G) Surface resistivity (Ω) After leaving the polyester film coated with the primer layer and dried at 23 ° C x 50% RH for 24 hours or more, a high resistance meter (Hiresta IP MCP-TESTER HT, manufactured by Diamond Instruments Co., Ltd.)
-260). H) Comprehensive evaluation The above evaluations were combined, and a 4-level evaluation was performed according to the following evaluation criteria. ◎: good ○: no problem level ×: there is a problem XX: there is a problem

Examples 1-4 Cationic surfactant (Hobolux DM), copolyester resin (A), and curing agent (Coronate HL)
Was dissolved in ethyl acetate such that the weight ratio of the solid content shown in Table 1 was obtained, and the mixture was sufficiently stirred. The curing agent was added in an amount of 0.3 part by weight based on 100 parts by weight of the copolymerized polyester. This solution was applied to a biaxially stretched PET film having a thickness of 50 μm by a wire bar coater and dried at 140 ° C. for 20 seconds to carry out a curing reaction to obtain a film having a primer layer having a coating amount of 0.02 g / m ² . Table 1 shows the performance of the obtained antistatic PET film.

Comparative Example 1 A 5% methanol solution of a cationic surfactant (Hobolux DM) was used as a primer layer without using a copolymerized polyester resin and a curing agent, and the coating amount was 0.02 g.
/ M ² except that the antistatic P
An ET film was obtained. Table 1 shows the performance of the obtained antistatic PET film.

Comparative Example 2 A copolymerized polyester resin (A) was used without a cationic surfactant (Hobolux DM) as a primer layer.
Was dissolved in a mixed solvent of toluene / methyl ethyl ketone = 1/1, a curing agent was added, and the mixture was sufficiently stirred. Using this solution, a film having a primer layer was obtained in the same manner as in Example 1. Table 1 shows the performance of the obtained PET film.

Comparative Example 3 Except that (B) was used as the copolymerized polyester resin,
An antistatic PET film was obtained in the same manner as in Example 3.
Table 1 shows the performance of the obtained PET film.

Comparative Example 4 An antistatic PET film was obtained in the same manner as in Example 3 except that Chemistat 3033 (sulfonic acid type anionic surfactant) was used as an antistatic agent. Table 1 shows the performance of the obtained PET film.

[0027]

[Table 1]

[0028]

According to the present invention, there are no troubles due to the generation of static electricity in processes such as coating and printing, and various inks and paints, such as gravure ink, offset ink, UV ink, chemical matte paint, and UV paint. For example, an antistatic polyester film having excellent adhesiveness to UV ink and excellent transparency can be provided.

────────────────────────────────────────────────── ─── Continuing on the front page (51) Int.Cl. ⁶ Identification code FI C09D 167/02 C09D 167/02 (72) Inventor Tomoko Yamanaka 31-3 Uji Hinojiri Uji-shi, Kyoto Unitika Uji Plastic Factory Co., Ltd. Inside

Claims (3)

[Claims] At least one surface of a polyester film contains 5 to 40% by weight of a cationic surfactant mainly composed of a quaternary ammonium salt represented by Chemical Formula 1 and 20 to 95% by mole of a terephthalic acid component. An antistatic polyester film provided with a primer layer comprising 95 to 60% by weight of a copolymerized polyester comprising an aromatic dicarboxylic acid and an aliphatic glycol. Embedded image 2. The antistatic polyester film according to claim 1, which has a surface resistivity of 10 ⁹ to 10 ¹² Ω. 3. The coating amount of the primer layer is 0.01 to 0.2 g / m ^2.
The antistatic polyester film according to claim 1 or 2, wherein