KR20160031303A - Heat shrinkable polyester film - Google Patents

Abstract

The present invention relates to a heat shrinkable polyester film and, more particularly, a heat shrinkable polyester film which has excellent basic characteristics as a heat shrinkable polyester film such as heat resistance, printing characteristics, uniform contraction, elongation processability, etc., and can embody blocking-resistance, anti-static property, and slip property through antistatic coating treatment. In the present invention, one side or both sides of a polyester substrate film is coated with an antistatic composition comprising a copolyester resin and a conductive polymer resin modified to have an average diameter less than or equal to 60 nm. Therefore, the heat shrinkable polyester film has excellent antistatic property while alleviating shortcomings of a conventional anionic antistatic coating layer of being vulnerable to moisture and a problem of whitening after a matte finish coating.

Description

Heat-shrinkable polyester film {HEAT SHRINKABLE POLYESTER FILM}

The present invention relates to a heat-shrinkable polyester film, and more particularly to a heat-shrinkable polyester film which is excellent in basic characteristics of a heat-shrinkable polyester film and can simultaneously achieve blocking resistance, antistatic property and slip property, And a heat shrinkable polyester film which overcomes the problems that caused the whitening phenomenon during the matte post-treatment coating.

Conventionally, polyvinyl chloride, polystyrene, polypropylene, polyethylene, or the like has been used as the heat shrinkable film.

Among these polyvinyl chloride films, environmental incompatibility is very poor due to chlorine gas and dioxin generation during incineration. The polystyrene-based film can be evaluated in terms of good finishing appearance after shrinkage. However, since the solvent resistance is poor, it is necessary to use an ink having a specific composition at the time of printing. The polypropylene-based film has poor shrinkability at low temperatures, and wrinkles and unevenness tend to occur at the shrinkage portion. In addition, the above films have a disadvantage that they are insufficient in heat resistance, are easily melted or ruptured during the processing of boiling and retorting, and are difficult to maintain the film state.

In recent years, studies on polyester-based heat-shrinkable films have been actively conducted to solve such problems, and they have been very popular as shrinkable labels replacing polyvinyl chloride films and polystyrene-based films, and the use of PET containers The amount of its use is gradually increasing.

However, since the heat-shrinkable polyester film can achieve uniform shrinkage due to low-temperature shrinkage and low shrinkage rate, good shrink appearance can be highly evaluated, but since the solvent resistance is poor, it is necessary to use a special composition ink But also has a problem in that it is difficult to store because of its large natural shrinkage ratio. Further, in the regeneration of the PET bottle, the polyester shrink film of the same material is disadvantageous in that it is difficult to separate the gravity difference and the recyclability is deteriorated. In addition, the heat-shrinkable polyester film may cause dust or the like in the air to adhere to the film due to static electricity in the labeling process at the time of post-processing, or may cause a cutting defect due to static electricity in a high-speed cutting process, There is a problem that the labels stick together.

In order to solve such a problem, Korean Unexamined Patent Publication No. 2002-0073305 suggests that antistatic property and blocking resistance can be improved by forming a coating layer containing a quaternary ammonium sulfate derivative and a polysiloxane resin on at least one side of a film . However, when an anionic antistatic agent is used, there is a problem in that it is difficult to optimize the user process, such as being weak in penetration of moisture and causing bleaching phenomenon in a post-matt treatment process.

Accordingly, the present inventors have made efforts to solve the above-mentioned problems. As a result, the present inventors have found that a coating composition containing a conductive polymer PEDOT and a copolyester resin having low water-dependence on one surface or both surfaces of a heat-shrinkable polyester film is coated with an antistatic layer The present inventors have completed the present invention by producing a heat shrinkable polyester film which realizes excellent antistatic property and at the same time improves whitening due to moisture.

Korea Patent Publication No. 2002-0073305

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a heat-shrinkable polyester film excellent in basic characteristics and capable of simultaneously achieving anti-blocking property, antistatic property and slip property, Shrinkable polyester film which has low antistatic property even at a low humidity and can prevent the whitening phenomenon during the matte post-treatment coating.

These and other objects and advantages of the present invention will become more apparent from the following description of a preferred embodiment thereof.

This object is achieved by a heat-shrinkable polyester film comprising an antistatic layer formed by coating an antistatic coating composition containing a conductive polymer resin on one or both sides of a polyester base film, wherein the surface resistance of the film under a humidity of 20% 10 ¹⁰ ? / Sq, and the heat shrinkage measured after immersing in hot water at 90 占 폚 for 10 seconds is 30% or more.

Here, the antistatic coating composition is an aqueous solution containing 100 to 1000 parts by weight of a copolymerized polyester and 0.001 to 10 parts by weight of a surfactant based on 100 parts by weight of the conductive polymer resin.

Preferably, the conductive polymer resin is distributed in a particle size with an average particle diameter of 60 nm or less.

Preferably, the conductive polymer resin is an aqueous dispersion containing a polyanion and a polythiophene-containing aqueous dispersion or a polyanion and a polythiophene derivative.

Preferably, the antistatic coating composition is characterized by a solid content of 0.5 to 10.0% by weight based on 100% by weight of the total coating composition.

Preferably, the heat-shrinkable polyester film has a difference in heat shrinkage in the main shrinkage direction measured after immersing in hot water at 90 ° C for 10 seconds and a difference in heat shrinkage in the main shrinkage direction measured after immersing in hot water at 80 ° C for 10 seconds 40% or less.

Preferably, the antistatic layer of the heat-shrinkable polyester film has a transmittance immediately after the coating of a non-light-emitting coating liquid in which inorganic silica particles are dispersed and a rate of change of transmittance within 1% after immersing in hot water at 90 ° C for 120 seconds .

Preferably, the haze value of the antistatic layer of the heat-shrinkable polyester film after coating with a non-coating liquid in which the inorganic silica particles are dispersed is within 10% of the haze value after drying for 120 seconds in hot water at 90 캜 .

Preferably, the dicarboxylic acid component of the polyester base film is terephthalic acid or dimethyl terephthalate, and the diol component is a mixture of 60 to 90 mol% of ethylene glycol with neopentyl glycol, 1,4-cyclohexanedimethanol, diethylene glycol , Propanediol, and butanediol, and 10 to 40 mol% of at least one diol selected from the group consisting of propanediol and butanediol.

More preferably, the polyester base film further comprises at least one of organic particles such as PE or PMMA, inorganic particles of silica or CaCO ₃ , and organic hybrid particles.

According to the present invention, the application range is much wider than that of the conventional ionic antistatic agent having excellent antistatic performance and high water dependency, and also the whitening phenomenon caused by moisture can be prevented, Can be minimized.

Further, the present invention can provide a heat-shrinkable polyester film which is manufactured by an in-line coating method, has low water dependence and is excellent in antistatic performance, blocking resistance and solvent adhesive strength, thereby minimizing defects in user processes And so on.

However, the effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings of the present invention. It will be apparent to those skilled in the art that these embodiments are provided by way of illustration only for the purpose of more particularly illustrating the present invention and that the scope of the present invention is not limited by these embodiments .

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control. Also, although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described herein.

In describing and / or claiming the present invention, the term "copolymer" is used to refer to a polymer formed by copolymerization of two or more monomers. Such copolymers include binary copolymers, terpolymers, or higher order copolymers.

The heat-shrinkable polyester film according to the first aspect of the present invention comprises an antistatic layer formed by coating an antistatic coating composition containing a conductive polymer resin on one or both sides of a polyester base film, The film has a surface resistance of less than 10 ¹⁰ ? / Sq and a heat shrinkage of 30% or more after immersing in hot water at 90 占 폚 for 10 seconds.

The antistatic coating composition may be an aqueous solution containing 100 to 1000 parts by weight of a copolymerized polyester and 0.001 to 10 parts by weight of a surfactant, based on 100 parts by weight of the conductive polymer resin.

The conductive polymer resin is preferably distributed in a particle size with an average particle diameter of 60 nm or less. More preferably, the particles are distributed in a particle size of 20 to 50 nm in average particle size, so that stable antistatic performance can be exhibited. At this time, if the average particle diameter of the conductive polymer swellings exceeds 60 nm, the dispersibility becomes poor and it becomes difficult to uniformly apply the aqueous solution.

More specifically, during the production of a film by an in-line coating method, a coating process is performed immediately before the transverse stretching. In the transverse stretching, the stretching stresses at the center portion and the edge portions are different from each other. At this time, in general, the edge portion has a larger elongation stress than the center portion, and the coating thickness of the edge portion is thinner than that of the edge portion, so that the deviation of the antistatic property between the center portion and the edge portion of the final film is more than 30%. For example, a heat-shrinkable polyester film having a surface resistivity of 10 ⁷ Ω / sq at the center of the film and a surface resistivity of 10 ¹⁰ Ω / sq at the edge and having a large deviation of antistatic property between the center and the edge can be obtained. This is a difficult problem.

The conductive polymer resin is preferably an aqueous dispersion containing a polyanion and a polythiophene or an aqueous dispersion containing a polyanion and a polythiophene derivative in order to impart excellent antistatic performance.

The polyanion is an acidic polymer, and includes a polymeric carboxylic acid or a polymeric sulfonic acid, and polyvinylsulfonic acid. Examples of the polymeric carboxylic acid include polyacrylic acid, polymethacrylic acid, and poly maleic acid, and examples of the polymeric sulfonic acid include polystyrene sulfonic acid and the like.

As the polythiophene, poly 3,4-ethylenedioxythiophene (PEDOT) and the like can be used.

By forming an antistatic layer by an inline coating method with an antistatic composition containing such a conductive polymer resin, it is possible to obtain a coating having excellent antistatic properties, weak points in moisture, which is a weak point of conventional antistatic antistatic coatings, A heat-shrinkable polyester film can be provided which is improved in the portion which has caused the heat-shrinkable polyester film.

In addition, the heat-shrinkable polyester film has excellent antistatic performance of less than 10 ¹⁰ Ω / sq in a humidity of 20% RH or less, and has a much wider range of applications than conventional ionic antistatic agents having high water-dependency , It is possible to minimize the defective rate in the user process by improving the whitening phenomenon that can be generated by moisture.

The copolyester resin contained in the antistatic coating composition of the present invention is applied to a film to increase solvent adhesion in the user process and to ensure anti-blocking properties. A preferred copolyester resin has a Tg of 60 to 80 캜.

The amount of the copolyester resin may be 100 to 1000 parts by weight of the copolyester resin per 100 parts by weight of the conductive polymer resin. If the amount of the copolyester resin is less than 100 parts by weight, the blocking resistance may be lowered and melt adhesion may occur during the user process. If the amount is more than 1000 parts by weight, sufficient solvent adhesion may not be achieved.

The antistatic coating composition of the present invention also includes a surfactant added to improve the stability, wetting and leveling of the coating composition.

The surfactant is preferably an acetylenediol surfactant, and it is possible to provide a heat-shrinkable polyester film having excellent quality and high yield by maintaining the coating properties such as blocking resistance and solvent adhesion while realizing excellent wettability and leveling ability have.

The content of the surfactant is 0.001 to 10 parts by weight based on 100 parts by weight of the conductive polymer resin. If the addition amount of the surfactant is less than 0.001 part by weight, the wettability of the coating film is deteriorated. If the amount is more than 10 parts by weight, coating appearance defects due to microbubbles in the coating composition are caused.

In addition, the antistatic coating composition of the present invention is preferably prepared such that the solid content is from 0.5 to 10.0% by weight, more preferably from 1.0 to 5.0% by weight, based on 100% by weight of the total coating composition. . When the content of the solid content is less than 0.5% by weight, it is not sufficient to develop the coating film formation and antistatic function of the coating layer. When the content is more than 10.0% by weight, the transparency of the film is undesirably affected.

The thickness of the antistatic layer is preferably 0.5 to 5.0 mu m.

The polyester base film can be prepared by copolymerization of a dicarboxylic acid and a diol component and addition of silica particles.

Preferred examples thereof include terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, sebacic acid, adipic acid, diphenyldicarboxylic acid, 5-tert-butylisophthalic acid, 2,2,6,6- Tetramethyldiphenyl-4,4'-dicarboxylic acid, 1,1,3-trimethyl-3-phenylindan-4,5-dicarboxylic acid, 5-sodium sulfoisophthalic acid, trimellitic acid Selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, azelaic acid, pyromellitic acid, 1,4-cyclohexanedicarboxylic acid, and 1,3-cyclohexanedicarboxylic acid. Or a mixture thereof, and a second dicarboxylic acid component composed of 60 to 90 mol% of ethylene glycol and 100 to 5 mol% of neopentyl glycol, 1,4-cyclohexanedimethanol, diethylene glycol, propanediol and butanediol , More preferably 10 to 40 mol% of at least one diol selected from the group consisting of ethylene, To prepare a copolymer polyester resin that Til the second component and the average particle diameter of diols consisting of 10 to 30 mole% glycol containing 1 ~ 5㎛ of silica particles 0.01 to 1% by weight based on the weight of polyester resin.

If the content of neopentyl glycol in the diol component is less than 10 mol%, the dimensional stability of the copolymer polyester is increased, a sufficient heat shrinkage is difficult to be realized, and the shrinkage rate and shrinkage stress are too high. If the content of neopentyl glycol is more than 30 mol%, crystallization of the produced chips is difficult, so that chips are welded to each other in a raw material drying process to prevent hydrolysis, thereby causing process troubles.

In addition to silica particles, organic particles such as PE and PMMA, inorganic particles such as CaCO ₃ , and organic hybrid particles may be used. The shape of these particles may be elliptical, hemispherical or hollow.

The heat-shrinkable polyester film according to the present invention is characterized in that the shrinkage measured after immersing in hot water at 90 ° C for 10 seconds is 30% or more in the main shrinkage direction. The heat shrinkage measured after immersing in hot water at 90 DEG C for 10 seconds is 30% or more, preferably 50% or more, and more preferably 70% or more. When the heat shrinkage rate is less than 30%, there is a problem that the shrinkage rate is insufficient when labeling a product having a bend in a bottle.

The heat shrinkable polyester film has a heat shrinkage ratio in the main shrinkage direction measured after immersing in hot water at 90 ° C for 10 seconds and a heat shrinkage difference in the main shrinkage direction measured after immersing in hot water at 80 ° C for 10 seconds is not more than 40% , Preferably not more than 30%.

In the temperature range of 80 to 90 占 폚, which is the steam temperature of a commonly used steam tunnel, the heat shrinkage difference is set to 40% or less so that shrinkage fluctuation caused by temperature fluctuation of water vapor is suppressed when labeling the object, This is because defective finishing defects such as pear marks can be suppressed.

In addition, the heat-shrinkable polyester film preferably has a transmittance immediately after being dried by applying a matte coating liquid in which inorganic silica particles are dispersed in an antistatic layer, and a rate of change of transmittance within 1% after immersed in hot water at 90 캜 for 120 seconds.

In addition, the heat-shrinkable polyester film preferably has a haze value immediately after drying, in which a non-coating liquid containing inorganic silica particles dispersed in an antistatic layer is dispersed, and a rate of change in haze value when removed after immersing in hot water at 90 캜 for 10 seconds.

Next, a method for producing the heat-shrinkable polyester film according to the present invention will be described.

The heat-shrinkable polyester film according to the present invention can be produced by a known method. The shape of the film may be either a plane shape or a tube shape, but a planar shape is preferable in view of productivity and printing on the inner surface. As a method of producing a flat film, for example, a resin is melt-extruded using a plurality of extruders, co-extruded from a T-die, and then cooled and solidified by a roll to obtain a sheet. The obtained sheet is stretched at a temperature not lower than the glass transition temperature by the tenter method without roll stretching in the longitudinal direction, and is heat-treated and cooled to obtain a film. The stretching temperature in the stretching step is preferably 60 to 100 占 폚, preferably 70 to 90 占 폚. If the stretching temperature is less than 60 캜, stretching occurs at a temperature lower than the glass transition temperature of the copolyester resin, so that breakage occurs and stretching is impossible. When the stretching temperature is 100 캜 or more, the elasticity of the material is lowered. Can not.

The stretching magnification is suitably in the uniaxial or biaxial stretching direction of 3.0 to 7.0 times, preferably 3.5 to 5.0 times in the main shrinkage direction depending on the properties of the resin composition to be used, the stretching means, the stretching temperature and the use of the product. When the stretching ratio is less than 3.0 times, it is difficult to realize a sufficient heat shrinkage. When the stretching ratio exceeds 7.0 times, the shrinking stress value becomes excessive, or the frequency of occurrence of fracture due to stretching beyond the yielding point is increased. Even in the case of uniaxial stretching in the transverse direction, it is also effective to give about 1.05 to 1.8 times of stretching in the longitudinal direction for the purpose of improving the mechanical properties in the longitudinal direction. The stretched film is subjected to heat treatment or relaxation treatment at a temperature of 100 DEG C or lower for the purpose of reducing the natural shrinkage ratio or improving the heat shrinkage property as required, and then the film is rapidly cooled within a time period during which the molecular orientation is not relaxed, A film can be obtained.

Further, the heat-shrinkable polyester film according to the present invention preferably has a thickness of 12 to 125 탆, and there is no specific thickness restriction when the film is produced. The heat-shrinkable laminated film of the present invention is mainly processed into a sleeve (cylindrical) shape. In the case of printing on a rectangular or cylindrical container such as a PET bottle, first, one side of a wide-width film on which a roll is wound is printed, cut into a required width, and folded folded and center sealed to form a cylindrical shape. Examples of the center sealing method include an adhesive method using an organic solvent, a method using an adhesive, and a method using an impulse sealer. Among these methods, an adhesive method using an organic solvent is preferably used from the viewpoints of productivity and appearance.

The heat-shrinkable polyester film according to the present invention is not particularly limited in its use, but may be formed by forming a printing layer, a vapor deposition layer, and other functional layers (antistatic function, running property improving function, It can be used for labeling and packaging of other molded products such as. When used as a heat-shrinkable label, it can be adhered to a complicated shape, and a container equipped with an elegant label free from wrinkles and puckering due to uneven shrinkage can be obtained.

The molded article or heat-shrinkable label according to the second aspect of the present invention is characterized by using the heat-shrinkable polyester film described above as a substrate.

The container according to the third aspect of the present invention is characterized in that the molded article or the heat-shrinkable label according to the second aspect is mounted.

Hereinafter, the structure and effect of the present invention will be described in more detail with reference to examples and comparative examples. However, this embodiment is intended to explain the present invention more specifically, and the scope of the present invention is not limited to these embodiments.

[Example]

<Production Example>

100 mol% of dimethyl terephthalate as a dicarboxylic acid component, 80 mol% of ethylene glycol as a diol component and 20 mol% of neopentyl glycol as a diol component were fed into an autoclave equipped with a stirrer and a distillation tower, and then manganese acetate 0.07% by weight based on the amount of dimethyl terephthalate. 2 kg / cm &lt; 2 &gt;, and the reaction was allowed to proceed while raising the temperature to 250 DEG C while removing water as a by-product. After the esterification reaction was completed, 0.02 wt% of trimethyl phosphate as a heat stabilizer was added to the second reactor equipped with a vacuum system, and 0.04 wt% of antimony trioxide was added as a polymerization catalyst in 10 minutes. Thereafter, while the temperature was gradually raised to 285 DEG C, the pressure was reduced gradually to 1 torr or less over 50 minutes, and the copolymer was polymerized for 240 minutes while removing the excess diol component through a vacuum line to obtain a copolymer polyester having an intrinsic viscosity of 0.70 dl / g. 0.07% by weight of amorphous spherical silica particles having an average particle diameter of 3 탆 was added to the obtained polymer and melt extruded at 250 캜, co-extruded from a T-die, and quenched by casting to obtain an unstretched sheet.

[Example 1]

The surface of the film to be coated in the unstretched sheet obtained in Production Example was subjected to corona discharge treatment to obtain a conductive polymer resin having an average particle diameter distribution of 35 ± 5 nm (0.5% by weight of poly 3,4-ethylenedioxythiophene and polystyrene sulfonic acid (Molecular weight Mn = 150,000)), 200 parts by weight of a copolyester resin, and 100 parts by weight of an acetylenic diol surfactant, 2,5,8,11-tetramethyldodecyne-5,8 0.1 part by weight of diol ethoxylate was mixed with water to prepare an antistatic coating solution. The solid content of the antistatic coating solution was 1.5% by weight based on the total antistatic coating solution. The antistatic coating aqueous solution was applied to a corona-treated surface by a Meyer bar coating method, followed by a preheating section maintained at 90 ° C by a tenter method, followed by stretching 4.0 times in a transverse direction at 80 ° C, followed by heat treatment at 60 ° C To prepare a heat shrinkable polyester film having a thickness of 50 탆.

[Example 2]

A heat-shrinkable polyester film was prepared in the same manner as in Example 1, except that 400 parts by weight of copolyester resin was added to the solid content in Example 1.

[Example 3]

A heat-shrinkable polyester film was prepared in the same manner as in Example 1, except that the solid content in Example 1 was 2.0 wt% based on the total antistatic coating solution.

[Comparative Example 1]

A heat-shrinkable polyester film was produced in the same manner as in Example 1, except that the conductive polymer resin having an average particle size distribution of 100 ± 10 nm was contained in Example 1.

[Comparative Example 2]

A heat-shrinkable polyester film was produced in the same manner as in Example 1 except that the solid content in Example 1 was 0.1 wt% based on the total antistatic coating solution

[Comparative Example 3]

Except that the antistatic coating composition was a coating solution containing 10 parts by weight of a methyl methacrylate copolymer and 40 parts by weight of an alkyl phosphate per 100 parts by weight of copolyester to obtain a heat-shrinkable polyester A film was prepared.

[Comparative Example 4]

50 parts by weight of a quaternary ammonium sulfate aqueous solution as an antistatic coating composition was added to 50 parts by weight of a mixed solvent of toluene, methyl ethyl ketone and isopropyl alcohol in a volume ratio of 5: 4: 1, and then quaternary ammonium sulfate was added to the total weight of the surface- By weight to 0.35% by weight. A heat-shrinkable polyester film was prepared in the same manner as in Example 1, except that the coating liquid was a coating liquid in which a polysiloxane resin was added in an amount of 0.3 wt% based on the total weight of the surface treatment composition.

[Comparative Example 5]

100 parts by weight of a copolymer polyester resin having a glass transition temperature of 25 DEG C as an antistatic coating composition was mixed with 100 parts by weight of an anionic compound (anionic compound described in Example 1 of Korean Patent Laid-open No. 10-2007-0080332) as an antistatic agent A heat-shrinkable polyester film was produced in the same manner as in Example 1, except that the coating liquid was prepared.

The properties of the heat-shrinkable polyester films according to Examples 1 to 3 and Comparative Examples 1 to 5 were measured through the following experimental examples, and the results are shown in Table 1 below.

[Experimental Example]

(1) Heat shrinkage

The film was cut into a square of 10 cm x 10 cm and immersed in hot water maintained at a temperature of 90 deg. C for 10 seconds in a no load state, and the length was measured. The heat shrinkage rate was determined according to the following formula.

Heat shrinkage percentage (%) = 100 X (length before shrinkage - length after shrinkage) / (length before shrinkage)

(2) Antistatic property

After standing for 8 hours under the conditions of 25 캜 x 55% RH, the antistatic property was evaluated by a surface resistance meter (ADVANTEST, manufactured by ADVANTAGE INC.). The unit is Ω / sq.

(3) Antistatic property under low humidity

After standing for 8 hours under the condition of 25 캜 x 20% RH, the antistatic property was evaluated with a surface resistance meter (ADVANTEST, manufactured by ADVANTAGE INC.). The unit is Ω / sq.

(4) Blocking resistance

The film coated side was abutted against each other using a roller type laminator at a temperature of 120 DEG C under a pressure of 2 kg / cm &lt; 2 &gt; at a speed of 5 mpm and peeled off. The anti-blocking properties were evaluated according to the following criteria.

○: It is peeled cleanly without stickiness.

△: The sticking mark remains but peelable.

X: Fusing between films occurs, and peeling is impossible.

(5) Solvent adhesion

The 1,3-dioxolane solvent was applied to an area of 20 x 5 mm ² with a brush at a coverage of 5 g / m ² , and then sealed with two films. The sealing part was set in a universal tensile tester STM-50 and measured at a tensile speed of 20 mm / min by a 180-degree peel test.

(6) Haze and total transmittance

The haze was measured using a haze meter according to JIS K7136.

(7) Printing characteristics

The nitrocellulose ink was coated on the surface of the film, and then a grid pattern was formed on the film-coated surface at regular intervals using a razor blade. Subsequently, when a 3M 610M scotch tape was adhered to the coated surface of the film and then rub-off test was rapidly performed (rub-off test), the degree of transfer of the ink on the tape adhesion surface was evaluated and evaluated as follows.

○: Ink transfer rate to 3M tape 0%

DELTA: ink transfer rate to 3M tape less than 30%

Х: 30% or more ink transfer rate for 3M tape

(8) Coating of inorganic particles

The particle coating in which the inorganic particles (silica) were contained in the coating layer coated with the antistatic composition was carried out by a graining coating method, and haze and total transmittance were measured immediately after drying and after immersion in hot water (90 캜, 120 sec).

As can be seen from Table 1, the heat-shrinkable polyester film according to the present invention is low in humidity dependency compared to the heat-shrinkable polyester film having antistatic property using the conventional ionic antistatic agent, It is possible to improve the weak point of moisture, which is a weak point of the conventional antioxidant coating, and the portion which caused the whitening phenomenon in the post-maturing post-treatment coating, although the antistatic property is excellent. As a result, it is possible to overcome the problem of bleaching at the time of sterilization process and to realize antistatic property even at low humidity, so that it can be used sufficiently in a low humidity region, and also has excellent solvent adhesion and blocking resistance.

However, in the case of Comparative Example 1, the particle diameter of the conductive polymer is increased and the dispersibility is lowered as compared with the embodiment, resulting in a disadvantage in that the antistatic property of the wet film (between the center of the film and the edge) is different. In addition, in the case of Comparative Example 2 in which the solid content is too small, blocking resistance can not be sufficiently secured. In the case of Comparative Examples 3, 4, and 5 using an ionic antistatic agent, antistatic properties can not be achieved in an environment of 20% RH or less in humidity. Immediately after the coating of the inorganic particles and the hot water immersion As a result, the ionic antistatic agent is vulnerable to moisture, and bleaching phenomenon occurs.

It is to be understood that the present invention is not limited to the above embodiments and various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention.

Claims (10)

A heat-shrinkable polyester film comprising an antistatic layer formed by coating an antistatic coating composition containing a conductive polymer resin on one side or both sides of a polyester base film,
Shrinkable polyester film characterized in that the surface resistivity of the film is less than 10 ¹⁰ ? / Sq under a humidity of 20% RH and the heat shrinkage measured after immersing in hot water at 90 占 폚 for 10 seconds is 30% or more. The method according to claim 1,
Wherein the antistatic coating composition is an aqueous solution containing 100 to 1000 parts by weight of a copolymerized polyester and 0.001 to 10 parts by weight of a surfactant based on 100 parts by weight of the conductive polymer resin. The method according to claim 1,
Wherein the conductive polymer resin is distributed in a particle size with an average particle size of 60 nm or less. The method according to claim 1,
Wherein the conductive polymer resin is a water dispersion containing a polyanion and a polythiophene-containing aqueous dispersion or a polyanion and a polythiophene derivative. The method according to claim 1,
Wherein the antistatic coating composition has a solids content of 0.5 to 10.0% by weight based on 100% by weight of the total coating composition. The method according to claim 1,
The heat shrinkable polyester film has a heat shrinkage ratio in the main shrinkage direction measured after immersing in hot water at 90 ° C for 10 seconds and a heat shrinkage difference in the main shrinkage direction measured after immersing in hot water at 80 ° C for 10 seconds is 40% Wherein the heat-shrinkable polyester film is a heat-shrinkable polyester film. The method according to claim 1,
Wherein the antistatic layer of the heat-shrinkable polyester film has a transmittance immediately after the coating of the matte coating liquid in which the inorganic silica particles are dispersed and a rate of change of the transmittance when the layer is immersed in the hot water for 90 seconds at 90 ° C within 1% Cast polyester film. The method according to claim 1,
Wherein the haze value of the antistatic layer of the heat-shrinkable polyester film immediately after the coating of the matless coating liquid in which the inorganic silica particles are dispersed is within 10% of the haze value after drying for 120 seconds in hot water at 90 占 폚 , Heat-shrinkable polyester film. 9. The method according to any one of claims 1 to 8,
Wherein the dicarboxylic acid component of the polyester base film is terephthalic acid or dimethyl terephthalate and the diol component is selected from the group consisting of 60 to 90 mol% of ethylene glycol and at least one of neopentyl glycol, 1,4-cyclohexanedimethanol, diethylene glycol, propanediol, And 10 to 40 mol% of at least one diol selected from the group consisting of butanediol. 10. The method of claim 9,
Wherein the polyester base film further comprises at least one of organic particles such as PE or PMMA, inorganic particles of silica or CaCO ₃ , and organic hybrid particles.