KR20010045907A - Heat-shrinkable polyester film - Google Patents

Abstract

PURPOSE: A heat-shrinkable polyester film having excellent thickness uniformity, heat shrinkage, antistatic effect and ultraviolet-screening effect as well as basic characteristics such as heat resistance, hot water resistance, chemical resistance, mechanical characteristics and printing characteristics is provided, which is useful as a label or coating use for vessel. CONSTITUTION: This film contains aromatic dicarboxylic acid as a repeating unit of an acid compartment and 30 to 60 mole of a total unit of a trimethylene glycol unit, a tetramethylene glycol unit, a 2,2-dimethyl(-1,3-propane)diol unit and an 1,4-cyclohexanedimethanol unit and 40 to 70 mole of an ethylene glycol unit as a repeating unit of a diol compartment based on the total diol component. The aromatic dicarboxylic acid is one or more selected from the group consisting of dimethylterephthalic acid, terephthalic acid, dimethylisophthalic acid and isophthalic acid.

Description

Heat-shrinkable polyester film

The present invention relates to a heat-shrinkable polyester film, and more particularly, it is excellent in basic properties such as heat resistance, chemical resistance, mechanical properties, printing characteristics, in particular, excellent thickness uniformity and heat shrinkage characteristics, antistatic effect and ultraviolet light The blocking effect is good, and relates to a heat shrinkable polyester film useful for labeling or coating of containers.

Heat-shrinkable films are used not only for labeling plastics, glass bottles, batteries or electrolytic capacitors, but also for the overall coating of packaging containers, and are used for various purposes such as packing or tightly packing stationery or several containers. As such heat-shrinkable films, not only films such as polyvinyl chloride and polystyrene, but also polyester films have been used in recent years.

In order to use the heat-shrinkable film for various packaging materials or labels, not only basic properties such as heat resistance, chemical resistance, weather resistance, and printing characteristics, but also excellent heat shrinkage properties such as sealing property and shrinkage uniformity are required.

However, in the case of polyvinyl chloride or polystyrene heat-shrinkable film, which is widely used as a conventional heat-shrink film material, there is a problem that heat resistance, chemical resistance, weather resistance, and heat shrinkage characteristics are not sufficient. In particular, the polyvinyl chloride heat-shrinkable film contains a chlorine component, so the environmental friendliness of the incineration waste is very poor. Since polystyrene film is poor in printability, it is impossible to use ink for general plastic film, so it is necessary to use special ink, and it is difficult to store because of its high natural shrinkage rate, and it causes problems such as poor printing in the printing process. have.

In recent years, the use of polyester containers has increased rapidly, and heat-shrinkable polyester films have been in the spotlight for easy recycling as labels.

Heat-shrinkable polyester film generally used is polyethylene terephthalate, which is excellent in heat resistance, chemical resistance and weather resistance, and hardly causes environmental pollution by carcinogens such as dioxins when incinerated. Doing.

However, since a film made of conventional polyester has various problems such as insufficient heat shrinkage rate, methods for improving the film have been proposed. Japanese Patent Laid-Open No. 63-139725 discloses a method for improving heat shrinkage, hot water resistance and solvent resistance by copolymerizing terephthalic acid and isophthalic acid as acid components and ethylene glycol and 1,4-cyclohexanedimethanol as diol components and stretching them. Japanese Patent Laid-Open Publication No. 63-156833 discloses a method of copolymerizing ethylene glycol and neopentyl glycol as an acid component and terephthalic acid as a diol component, followed by stretching. In addition, Korean Patent Publication 92-7711 discloses a method of copolymerizing ethylene glycol, propanediol derivatives and bisphenolsulfonic acid derivatives as terephthalic acid and diol components to improve shrinkage uniformity, heat resistance, and printability. A method of improving shrinkage characteristics and shrinkage uniformity of a film by copolymerizing and stretching ethylene glycol, diethylene glycol and neopentyl glycol as terephthalic acid and a diol component is disclosed. In addition, Korean Patent Publication 95-590 discloses a method of copolymerizing and stretching ethylene glycol and neopentyl glycol as acid components and diol components of terephthalic acid and isophthalic acid. However, these methods have a poor thickness uniformity and stretchability of the film, not only a narrow tolerance of stretching conditions, but also a lack of shrinkage uniformity.

In addition, Japanese Patent Laid-Open No. 7-216107 discloses a method of copolymerizing butanediol and neopentyl glycol as a terephthalic acid and a diol component, followed by stretching to improve shrinkage uniformity and heat resistance. Is poor, and the breaking strength of the film with respect to the main shrinkage direction and its vertical direction is low, which causes problems in film forming. In addition, since the ink adhesion and the film thickness after shrinkage is not uniform, the appearance is poor.

Therefore, the technical problem to be solved by the present invention is not only excellent in basic properties such as heat resistance, hot water resistance, chemical resistance, mechanical properties, printing characteristics by solving the above problems, in particular, excellent thickness uniformity and heat shrinkage characteristics, and antistatic effect and The sunscreen effect is good, to provide a heat-shrinkable polyester film useful for labeling or whole coating of various containers.

In order to achieve the above technical problem, the present invention includes an aromatic dicarboxylic acid as an acid component repeating unit, compared to the total diol component, trimethylene glycol unit, tetramethylene glycol unit, 2,2-dimethyl (-1,3 Provided is a heat-shrinkable polyester film comprising a diol component repeating unit having a total amount of -propane) diol units and 1,4-cyclohexanedimethanol units of 30 to 60 moles and 40 to 70 moles of ethylene glycol units. .

The heat-shrinkable polyester film is a sulfonic acid metal salt derivative represented by R1-SO ₃ Me (wherein R1 is an alkyl group having 5 to 20 carbon atoms, Me is an alkaline earth metal or an alkali metal) in order to improve antistatic properties. It is preferable to further include 0.01 to 1.0 weight relative to the film.

Preferably, the heat-shrinkable polyester film further comprises 0.01 to 1.0 weight of a hydroxyphenylbenzotriazole compound based on the total weight of the film as a sunscreen.

Hereinafter, a heat shrinkable polyester film and a method of manufacturing the same according to the present invention will be described in more detail.

The present invention includes an aromatic dicarboxylic acid as the acid component repeating unit, compared to the total diol component, trimethylene glycol unit, tetramethylene glycol unit, 2,2-dimethyl (-1,3-propane) diol unit and 1 Provided is a heat-shrinkable polyester film comprising a diol component repeating unit having a total amount of, 4-cyclohexanedimethanol units of 30 to 60 mol and an ethylene glycol unit of 40 to 70 mol.

The polyester film of the present invention has a predetermined amount of trimethylene glycol units, tetramethylene glycol units, 2,2-dimethyl (-1,3-) based on acidic components containing aromatic dicarboxylic acids as main components, and alkylene glycols as main components. It can obtain by polycondensing the diol component of a propane) diol unit and a 1, 4- cyclohexane dimethanol unit.

Dimethyl terephthalate, terephthalic acid, dimethyl isophthalate, isophthalic acid and the like can be used as the aromatic dicarboxylic acid component.

In general, the heat shrinkage properties of a polyester film are caused by the amorphousness of the polyester molecular chain itself, each of the diol components according to the present invention, in addition to forming an amorphous state that can give the film sufficient heat shrinkage properties, the desired mechanical properties And surface characteristics. Specifically, the trimethylene glycol unit of the polyester film improves printability by increasing the surface adhesion of the polyester film. Tetramethylene glycol units improve the thickness uniformity of the film by imparting good stretching properties.

In addition, 2,2-dimethyl (-1,3-propane) diol units contribute sufficient heat shrinkability to the film by contributing to enhancing the amorphousness of the entire polyester molecular chain. In addition, since the 2,2-dimethyl (-1,3-propylene) diol unit has a branched molecular structure, it is possible to increase the mechanical properties in the stretching direction and the vertical direction of a uniaxially stretched polyester film. The layer cracking phenomenon which appears in a polyester film can be prevented. Therefore, uniaxial stretching of sufficient magnification is possible. In addition, the 1,4-cyclohexanedimethanol unit serves to suppress the non-uniform shrinkage phenomenon at high temperature shrinkage to increase the product value of the contracted final product.

As such, when the total amount of each of the diol units that play a complementary role is less than 30 moles, the heat shrinkage cannot be represented sufficiently, and when the amount exceeds 60 moles, the content of ethylene glycol units decreases relatively. And there is a problem that the heat resistance is lowered. In particular, 2-15 mol of trimethylene glycol units, 10-30 mol of tetramethylene glycol units, 7-20 mol of 2,2-dimethyl (-1,3-propane) diol units within the above range, 1,4-cyclohexane It is preferred to include 2 to 15 moles of dimethanol units.

In the present invention, in addition to the components described above, other components may be included within a range that does not affect the polyester-based heat shrink film properties of the present invention. For example, ester acid of isophthalic acid, 2,6-naphthalenedicarboxylic acid or its esterified product, sebacic acid, adipic acid, 5-sodiumsulfurisophthalic acid, trimellitic acid, oxalic acid, Diols and xylenes of diethylene glycol, hexanediol, 2,2 (4-oxyphenol) propane derivatives as polycarboxylic acids and diol components such as malonic acid, succinic acid, glutaric acid, pimeric acid, azelaic acid and pyromellitic acid Polyhydric alcohol components, such as glycol, butanediol, and triethylene glycol, can be used.

In addition, the heat-shrinkable polyester film of the present invention is a sulfonic acid metal salt derivative represented by R1-SO ₃ Me (wherein R1 is an alkyl group having 5 to 20 carbon atoms and Me is an alkaline earth metal or an alkali metal) compared to the polyester film. It may further comprise 0.01 to 0.1 weight. Since the surface resistance of a conventional polyester film is 1 × 10 ¹⁵ kPa or more, products shrink-wrapped with such a film are easily contaminated with dust or foreign matters, resulting in deterioration of product value. Coating the antistatic agent on the film as a method for preventing the contamination of the film is not preferable because the shrinkage of the film in advance during the heat treatment process during the coating process is poor heat shrinkage characteristics. Therefore, in the present invention, the sulfonic acid metal salt derivative is mixed with the polyester film so as not to affect the heat shrinkage characteristic of the film.

The content of the sulfonic acid metal salt derivative contained in the polyester film of the present invention is preferably 0.01 to 0.1 weight compared to the polyester film, by adding a sulfonic acid metal salt derivative in this range without degradation of the polyester film and deterioration of mechanical properties The antistatic property of a polyester film can be improved so that the resistivity of the surface of a polyester film may be 2 * 10 <^13> Pa or less. The sulfonic acid metal salt derivative may be an acid value of 1.0 mgKOH / g or less, and may be used, such as potassium olylbenzenesulfonate, potassium nonylbenzenesulfonate, potassium undecylbenzenesulfonate, and the like. It is preferred that it is a metal selected from the group consisting of magnesium.

The heat shrinkable polyester film according to the present invention may further include 0.01 to 1.0 weight of the hydroxyphenylbenzotriazole-based compound based on the total weight of the film. As the sunscreen, if the amount of the hydroxyphenylbenzotriazole compound added is less than 0.01 weight, the sunscreen effect is not sufficient, and if the amount exceeds 1.0 weight, the sunscreen property no longer affects the improvement of the sunscreen property, and the cost increases as the amount is increased. Rise and cause degradation of the polyester, which may lower the mechanical properties of the film. The hydroxyphenylbenzotriazole-based compound is more preferably 2- [2-hydroxy-3,5-di- (1,1-diketylbenzyl) phenyl] -2H-benzotriazole. Since the ultraviolet transmittance of a conventional polyester film is 90 or more, a container packed with such a film loses its freshness rapidly when exposed to sunlight. Therefore, by adding the hydroxyphenylbenzotriazole-based compound according to the present invention to the polyester film, the ultraviolet transmittance can be lowered to 30 or less based on the film thickness of 50 µm with respect to the wavelength of 345 nm, and thus, food, especially juice drink container When the entire coating is applied, the shelf life can be extended by preventing the decrease of freshness caused by ultraviolet rays and the deterioration of taste.

The heat-shrinkable polyester film of the present invention has a surface adhesiveness of at least 5B based on ASTM D3359 with respect to nitrocellulose-based inks, and the breaking strengths of the film's main shrinkage direction and its vertical direction are 18 kgf / mm 2 and 5 kgf, respectively. / Mm &lt; 2 &gt; or more, thickness variation is less than 5, shrinkage rate in the main shrinkage direction is 60 or more in 80 캜 hot water, and shrinkage rate in the vertical direction to the main shrinkage direction is less than 5 degrees. Therefore, the printability for the ink is good, the delamination of the film does not occur, and the end sorption phenomenon is minimized. Moreover, the thickness is uniform and the appearance is beautiful. In addition, the polyester film of the present invention has a film thickness deviation of less than 10 after shrinkage in the main shrinkage direction at 80 ° C. hot water, which is considerably good after shrinkage, and a film thickness deviation after 30 shrinkage in the main shrinkage direction at 40 ° C. hot water. Since less than 10, the thermal deformation at room temperature is also minimized.

Whiteness of 80 or more based on ASTM E313, light transmittance of 40 µm thick films of 40 or less based on ASTM D1003, and surface adhesion of nitrocellulose-based inks of film 5B or higher based on ASTM D3359 ego. Shrinkage in the main shrinkage direction is 40 or more, and shrinkage in the vertical direction to the main shrinkage direction is less than 5 in 80 ℃ hot water. Since it is a white opaque film, it can have a beautiful appearance by a simple printing process of 1 to 3 degrees without going through complicated gravure printing of 5 degrees or more. Ink adhesion is good and it has excellent printability. In addition, the end shrinkage phenomenon is minimized because the shrinkage in the main contraction direction is greater than 40 and the shrinkage in the vertical direction is small in 80 ° C. hot water.

The acid component and diol component which comprise the said heat-shrinkable polyester film can be synthesize | combined by a well-known method, for example, the direct ester method or the transesterification reaction method.

The heat shrinkable polyester-based mixture constituting the film of the present invention may include various additives necessary for the production of the polyester film. For example, spherical silica, gel-type silica, alumina, kaolin, calcium carbonate, or the like may be added to improve the running property of the film in preparing the polymers.

The heat shrinkable polyester film of the present invention can be produced, for example, as follows.

To include each repeating unit, for example, a homopolymer of aromatic dicarboxylic acid and ethylene glycol unit, a homopolymer of aromatic carboxylic acid and tetramethylene glycol, a homopolymer of aromatic carboxylic acid and tetramethylene glycol unit, aromatic dicar Copolymerized polyesters of an acid with ethylene glycol and 2,2-dimethyl (1,3-propane) diol units and a mixture consisting of aromatic carboxylic acid and copolymerized polyesters of ethylene glycol and 1,4-cyclohexanedimethanol are conventional methods. Depending on the extrusion molding can be prepared by the step of cooling solidification → uniaxial or biaxial stretching. If necessary, the final heat-setting step is completed. In order to impart antistaticity or ultraviolet shielding property to the film, a sulfonic acid metal salt derivative or hydroxyphenylbenzotriazole-based compound may be added during polymerization or mixture preparation.

In more detail, first, the mixture and the sulfonic acid metal salt derivative or the hydroxyphenylbenzotriazole-based compound are kneaded well and extruded to form a melt sheet. In the extrusion molding, the hot melt of the mixture is usually carried out using an extrusion molding machine, but in some cases, the molding may be carried out in a softened state without heating the melt. The extruder used herein may be a single screw extruder, a biaxial coaxial or two-way extruder, but it is preferable to use a single screw extruder having a high kneading property for uniformity of physical properties. In such an extruder, a melt sheet obtained by melting and kneading the mixture is extruded through a die to obtain a melt sheet. Examples of dies used are T-dies and circular rings.

Subsequently, a solidified sheet is prepared by rapid cooling the melt sheet extruded from the die. Such cooling and solidification is preferably performed using a metal roll using a refrigerant such as gas or liquid. In the case of using a metal roll, it is possible to obtain an effect of making the sheet thickness uniform and improving surface characteristics. It is preferable to perform cooling solidification in the state with comparatively little orientation.

Subsequently, the cooling-solidified sheet is simultaneously or sequentially stretched on at least one axis, and in order to increase the uniformity of the thickness, it is preferable to perform the successive stretching.

According to one embodiment of the present invention, the film primarily drawn in the longitudinal direction is stretched in the transverse direction, that is, in a 90 ° direction with respect to the film running direction, if necessary. The stretching method is not particularly limited as long as it is a method commonly used in the art. Among them, tenter transverse stretching is the most typical stretching method. Specifically, both ends of the film being driven are fixed with clips running continuously, and the fixed state is gradually increased by increasing the distance between the clips at both ends in a suitable temperature atmosphere. It is a stretching method to perform.

Since the heat-shrinkable polyester film according to the present invention has good stretching properties, such a tenter method can be applied as it is, and thus a film having excellent stretch uniformity and thickness uniformity can be produced. Therefore, when it is used as a packaging material or label of various containers, it has a beautiful appearance due to the uniform shrinkage property.

In addition, the stretching method to be used is various, such as a method using gas pressure, a method by rolling, etc., and these may be appropriately selected or combined.

Heat-setting is performed as needed in order to adjust the thermal contraction rate with respect to the film obtained by extending | stretching on such conditions. For example, it is preferable to carry out for 10 to 30 seconds at 80 to 100 ° C. in the stretched state, relaxed state or limited shrinkage state of the stretched film after stretching. The heat setting temperature most suitable for the film may vary depending on the speed of the film passing through the heat treatment section, that is, the treatment time.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, it is a matter of course that the scope of the present invention is not limited to the following examples.

EXAMPLE

Production Example

100 mole parts of dimethyl terephthalate and 180 mole parts of ethylene glycol were added to an autoclave equipped with a distillation machine. At 150 ° C., manganese acetate was added 0.05 wt.% To dimethyl terephthalate as a transesterification catalyst. Reaction was advanced, heating up to 220 degreeC. After the transesterification reaction, 0.045 weight of trimethyl phosphate was added to dimethyl terephthalate as a stabilizer, and 0.03 weight of antimony trioxide was added to the polymerization catalyst after 10 minutes. Subsequently, after 5 minutes, the mixture was transferred to a second reactor equipped with a vacuum equipment, and then polymerized at 280 ° C. for about 140 minutes to obtain a homopolymer (A) of polyethylene terephthalate having an intrinsic viscosity of 0.62.

Polymerization was carried out in the same manner as the homopolymer (A) of polyethylene terephthalate, except that trimethylene glycol was used instead of ethylene glycol as a diol component, thereby obtaining a polytrimethylene terephthalate homopolymer (B) having an intrinsic viscosity of 0.85. Got it.

A homopolymer of the above polyethylene terephthalate was used except that 160 mol parts of 1,4-butanediol was used instead of 180 mol parts of ethylene glycol as a diol component and 0.03 weight of tetramethylene titanate was used instead of manganese acetate as a transesterification catalyst (A The polymerization was carried out in the same manner as) to obtain a polybutylene terephthalate homopolymer (C) having an intrinsic viscosity of 0.95.

Also, the same method as the homopolymer (A) of polyethylene terephthalate except that 90 mol parts of ethylene glycol and 90 mol parts of 2,2-dimethyl (-1,3-propane) diol was used instead of 180 mol parts of ethylene glycol as the diol component. The polymerization was carried out to give 2,2-dimethyl (-1,3-propane) diol copolymerized polyester (D) having an intrinsic viscosity of 0.64.

The polymerization was carried out in the same manner as the homopolymer (A) of polyethylene terephthalate, except that 36 mol parts of ethylene glycol and 144 mol parts of 1,4-cyclohexanedimethanol were used instead of 180 mol parts of ethylene glycol as the diol component. Cyclohexanedimethanol copolyester (E) having an intrinsic viscosity of 0.65 was obtained.

Examples 1-11 and Comparative Examples 1-7

Polyethylene terephthalate homopolymer (A), polytrimethylene terephthalate homopolymer (B), polybutylene terephthalate homopolymer (C) produced by the above method, 2,2-dimethyl (-1,3-propane ) Diol co-polyester (D) and cyclohexane dimethanol co-polyester (E) was dried using a vacuum dryer so that the moisture content is 0.05 weight or less, and the composition ratios A, B, C, D as shown in Table 1 And E was mixed. Ethylene glycol unit, trimethylene glycol unit, tetramethylene glycol unit, 2,2-dimethyl (-1,3-propane) diol unit and 1,4- constituting the mixed polyester according to the examples and comparative examples of Table 1 The content of cyclohexanedimethanol unit is analyzed and shown in Table 2.

Subsequently, the mixed polyester was melt-extruded at 280 ° C. and cooled on a casting roll maintained at 30 ° C. to obtain an amorphous sheet. The amorphous sheet thus obtained was continuously stretched 3.6 times in a tenter to obtain a uniaxially stretched heat shrinkable polyester film having a thickness of 50 µm.

Example 12

It carried out similarly to Example 1 except having added 95 mol part of dimethyl terephthalates and 5 mol part of dimethyl isophthalates instead of 100 mol parts of dimethyl terephthalates as an acid component.

Examples 13-15 and Comparative Examples 8-9

After the completion of the transesterification reaction in the preparation of the homopolymer (A) of the prepared polyethylene terephthalate, potassium olylbenzenesulfonate was added at the same time as the stabilizer was added so that the content of potassium olylbenzenesulfonate in the final film was as shown in Table 3. Except that was carried out in the same manner as in Example 1.

Examples 16-18 and Comparative Examples 10-11

After the transesterification reaction in the preparation of homopolymer (A) of the prepared polyethylene terephthalate, 2- [2-hydroxy-3,5-di- (1,1-diketylbenzyl) phenyl ] -2H-benzotriazole was added, and the content of 2- [2-hydroxy-3,5-di- (1,1-diketylbenzyl) phenyl] -2H-benzotriazole was measured in the final film. It carried out similarly to Example 1 except having made it like this.

Example 19

After the completion of the transesterification reaction in the preparation of the homopolymer (A) of the prepared polyethylene terephthalate, potassium stabilizers and 2- [2-hydroxy-3,5-di- (1,1- Diketylbenzyl) phenyl] -2H-benzotriazole was added to the final film, potassium olylbenzenesulfonate and 2- [2-hydroxy-3,5-di- (1,1-diketylbenzyl) phenyl]- The same procedure as in Example 1 was carried out except that the content of 2H-benzotriazole was set as shown in Table 3.

Composition of film A B C D E weight weight weight Copolymerization mole weight Copolymerization mole weight EG DMPG EG CHDM Example 1 40 8 18 50 50 24 20 80 10 Example 2 35 8 18 50 50 24 20 80 15 Example 3 43.75 8 18 50 50 24 20 80 6.25 Example 4 28 8 18 50 50 36 20 80 10 Example 5 48 8 18 50 50 16 20 80 10 Example 6 33 8 25 50 50 24 20 80 10 Example 7 46 8 12 50 50 24 20 80 10 Example 8 36 12 18 50 50 24 20 80 10 Example 9 43 5 18 50 50 24 20 80 10 Example 10 27.5 10 20 50 50 30 20 80 12.5 Example 11 51.5 6 15 50 50 20 20 80 7.5 Example 12 40 8 18 50 50 24 20 80 10 Comparative Example 1 12 12 25 50 50 36 20 80 15 Comparative Example 2 66 4 11 50 50 14 20 80 5 Comparative Example 3 42 10 20 50 50 28 20 80 0 Comparative Example 4 57.5 10 20 50 50 0 20 80 12.5 Comparative Example 5 49.5 10 0 50 50 28 20 80 12.5 Comparative Example 6 48 0 18 50 50 24 20 80 10 Comparative Example 7 100 0 0 50 50 0 20 80 0 Example 13 40 8 18 50 50 24 20 80 10 Example 14 40 8 18 50 50 24 20 80 10 Example 15 40 8 18 50 50 24 20 80 10 Comparative Example 8 40 8 18 50 50 24 20 80 10 Comparative Example 9 40 8 18 50 50 24 20 80 10 Example 16 40 8 18 50 50 24 20 80 10 Example 17 40 8 18 50 50 24 20 80 10 Example 18 40 8 18 50 50 24 20 80 10 Comparative Example 10 40 8 18 50 50 24 20 80 10 Comparative Example 11 40 8 18 50 50 24 20 80 10 Example 19 40 8 18 50 50 24 20 80 10

In Table 1, polymers A, B, C, D and E are homopolymers of polyethylene terephthalate, polytrimethylene terephthalate homopolymer, polybutylene terephthalate homopolymer, 2,2-dimethyl (-1,3), respectively. -Propane) diol copolymerized polyester and cyclohexanedimethanol copolymerized polyester, EG is ethylene glycol and DMPG is 2,2-dimethyl (-1,3

-Propane) diol and HDPB refers to 1,4-cyclohexanedimethanol.

Composition of film Acid component repeat unit Diol repeating unit TPA IPA EG Tri-MG Tet-MG DMPG CHDM mole mole mole mole mole mole mole Example 1 100 0 54 8 18 12 8 Example 2 100 0 50 8 18 12 12 Example 3 100 0 57 8 18 12 5 Example 4 100 0 48 8 18 18 8 Example 5 100 0 58 8 18 8 8 Example 6 100 0 47 8 25 12 8 Example 7 100 0 60 8 12 12 8 Example 8 100 0 50 12 18 12 8 Example 9 100 0 57 5 18 12 8 Example 10 100 0 45 10 20 15 10 Example 11 100 0 63 6 15 10 6 Example 12 95 5 54 8 18 12 8 Comparative Example 1 100 0 33 12 25 18 12 Comparative Example 2 100 0 74 4 11 7 4 Comparative Example 3 100 0 55 10 20 14 0 Comparative Example 4 100 0 60 10 20 0 10 Comparative Example 5 100 0 66 10 0 14 10 Comparative Example 6 100 0 62 0 18 12 8 Comparative Example 7 100 0 100 0 0 0 0 Example 13 100 0 54 8 18 12 8 Example 14 100 0 54 8 18 12 8 Example 15 100 0 54 8 18 12 8 Comparative Example 8 100 0 54 8 18 12 8 Comparative Example 9 100 0 54 8 18 12 8 Example 16 100 0 54 8 18 12 8 Example 17 100 0 54 8 18 12 8 Example 18 100 0 54 8 18 12 8 Comparative Example 10 100 0 54 8 18 12 8 Comparative Example 11 100 0 54 8 18 12 8 Example 19 100 0 54 8 18 12 8

In Table 2, TPA and IPA refer to terephthalic acid and isophthalic acid, respectively, and EG, Tri-MG, Tet-MG, DMPG and CHDM are ethylene glycol trimethylene glycol, tetramethylene glycol, 2,2-dimethyl (-1), respectively. , 3-propane) diol and 1,4-cyclohexanedimethanol.

Various performance evaluations of the films prepared according to the Examples and Comparative Examples were carried out as follows, and the results are shown in Table 3.

(1) Surface Adhesion to Nitrocellulose Inks

It was measured according to ASTM D3359-83.

(2) breaking strength

For samples prepared with the film having a length of 10 cm and a width of 15 mm, the breaking strength in the main shrinkage direction and the vertical direction of the film was measured using UTM at room temperature.

(3) thermal shrinkage

The prepared film was cut into a width of 15 mm and a length of 200 mm and then heat treated for 10 seconds in hot water maintained at 80 ° C., and then the length before and after the heat treatment was measured and calculated by the following equation.

Thermal Shrinkage () = [(L- ) / L] × 100

Where L is the length of the film before heat treatment, Is the length of the film after heat treatment.

(4) natural shrinkage

After the prepared film was cut into a width of 15 mm and a length of 200 mm and left for 7 days in an oven maintained at 40 ° C., the length before and after standing was measured, and the natural shrinkage was calculated by the same formula as the thermal shrinkage.

(5) Surface resistivity

The resistivity of the surface was measured using the insulation resistance measuring device of the United States Hewlett, 20 ℃, RH 65, applied voltage 500V.

(6) thickness deviation of film

50 points were measured at 5 cm intervals in the longitudinal direction and the transverse direction of the film, respectively.

Thickness deviation of film () = (T _max -T _min ) / (T _ave ) × 100

Where T _max is the maximum thickness of the film, T _min is the minimum thickness of the film, and T _ave is the average thickness of the film.

(7) UV transmittance

The transmittance with respect to the wavelength of 345 nm was measured using the UV-Visible Meter (Shumatsu, UV-265FW model).

(8) appearance of film

The external appearance of the film contracted 30 in the vertical direction of the main contraction direction in 80 ℃ hot water was visually judged.

◎: Good appearance (no wrinkles or cloudy appearance)

△: appearance normal

×: Poor appearance (wrinkles and turbidity)

Added amount compared to film Characteristics of the film OBSK HDPB Thickness deviation NC Ink Adhesive Breaking strength Natural shrinkage Heat shrinkage Post-Shrinkage Characteristics ¹⁾ Surface specific resistance UV transmittance MD TD TD TD MD Thickness deviation Exterior weight weight Rating kgf / mm2 kgf / mm2 Ω Example 1 - - 2 5B 7.2 23.8 0.2 71 3 7 ◎ 10 ¹⁵ ↑ 90 ↑ Example 2 - - 2 5B 7.1 22.4 0.2 73 3 6 ◎ 10 ¹⁵ ↑ 90 ↑ Example 3 - - 2 5B 7.2 24.1 0.5 69 2.5 8 ◎ 10 ¹⁵ ↑ 90 ↑ Example 4 - - 2 5B 9.8 21.7 0.2 72 3 7 ◎ 10 ¹⁵ ↑ 90 ↑ Example 5 - - 2 5B 6.2 24.3 0.2 70 3.5 7 ◎ 10 ¹⁵ ↑ 90 ↑ Example 6 - - 0.5 5B 7 21.5 0.2 71 3.5 7 ◎ 10 ¹⁵ ↑ 90 ↑ Example 7 - - 3.5 5B 6.9 24.5 0.2 70 3 7 ◎ 10 ¹⁵ ↑ 90 ↑ Example 8 - - 2 5B 7.1 22.4 0.2 74 3 7 ◎ 10 ¹⁵ ↑ 90 ↑ Example 9 - - 2 5B 7.1 24.2 0.2 68 2.5 7 ◎ 10 ¹⁵ ↑ 90 ↑ Example 10 - - 1.5 5B 8.2 20.9 0.2 75 3 7 ◎ 10 ¹⁵ ↑ 90 ↑ Example 11 - - 3 5B 6.8 24.6 0.2 66 2.5 8 ◎ 10 ¹⁵ ↑ 90 ↑ Example 12 - - 2 5B 6.3 21.3 0.2 71 3 7 ◎ 10 ¹⁵ ↑ 90 ↑ Comparative Example 1 - - 4.5 5B 4.1 15.9 1.3 66 7 13 △ 10 ¹⁵ ↑ 90 ↑ Comparative Example 2 - - 6.5 5B 3.5 23.9 0.8 52 11 15 △ 10 ¹⁵ ↑ 90 ↑ Comparative Example 3 - - 2 5B 7.2 23.5 1.8 66 4 23 × 10 ¹⁵ ↑ 90 ↑ Comparative Example 4 - - 2 5B 0.5 23.1 0.2 58 6 10 △ 10 ¹⁵ ↑ 90 ↑ Comparative Example 5 - - 12 5B 7.1 22.7 0.2 59 5 9 × 10 ¹⁵ ↑ 90 ↑ Comparative Example 6 - - 2 3B 7.1 23.5 0.2 71 3 11 △ 10 ¹⁵ ↑ 90 ↑ Comparative Example 7 - - 15.7 3B 0.1 24.9 0.3 38 17 23 × 10 ¹⁵ ↑ 90 ↑ Example 13 0.1 - 2 5B 7.2 23.5 0.2 71 3 7 ◎ 2 × 10 ¹¹ 90 ↑ Example 14 0.3 - 3 5B 7.3 23.5 0.2 71 3 7 ◎ 1 × 10 ¹⁰ 90 ↑ Example 15 0.03 - 2 5B 7.1 23.5 0.2 71 3 7 ◎ 2 × 10 ¹² 90 ↑ Comparative Example 8 2.5 - 11 5B 6.7 16.2 0.2 71 3 7 × 1 × 10 ¹⁰ 90 ↑ Comparative Example 9 0.002 - 2 5B 7.1 23.5 0.2 71 3 7 ◎ 10 ¹⁵ ↑ 90 ↑ Example 16 - 0.2 2 5B 7.2 23.5 0.2 71 3 7 ◎ 10 ¹⁵ ↑ 10 Example 17 - 0.5 3 5B 7.1 23.5 0.2 71 3 7 ◎ 10 ¹⁵ ↑ 1 ↓ Example 18 - 0.05 2 5B 7.2 23.5 0.2 71 3 7 ◎ 10 ¹⁵ ↑ 20 Comparative Example 10 - 2.5 8 5B 6.6 16.9 1.2 58 6 12 × 10 ¹⁵ ↑ 1 ↓ Comparative Example 11 - 0.002 2 5B 7.1 23.5 0.2 70 3 7 ◎ 10 ¹⁵ ↑ 50 Example 19 0.1 0.2 2 5B 7.4 23.5 0.2 71 3 7 ◎ 2 × 10 ¹¹ 10

In Table 3 above, OBSK is potassium olylbenzenesulfonate, HDPB is 2- [2-hydroxy-3,5-di- (1,1-diketylbenzyl) phenyl] -2H-benzotriazole, and NC is nitro Cellulose-based inks, MD and TD are shrinkage rates in the film's main shrinkage direction (horizontal direction) and its vertical direction (longitudinal direction), respectively, at 80 ° C. hot water, and post-shrinkage characteristic ¹⁾ is 30 in the main shrinkage direction at 80 ° C. hot water. Refers to the property after shrinkage.

Referring to Table 3, it is understood that the heat-shrinkable polyester films of Examples 1 to 19 prepared according to the present invention not only have good ink adhesion, mechanical properties, shrinkage characteristics, appearance, and the like, but also have particularly small thickness deviations. Can be.

Meanwhile, in the heat-shrinkable polyester film of the present invention, trimethylene glycol units, tetramethylene glycol units, 2,2-dimethyl (-1,3-propane) diol units and 1,4-cyclo relative to all diol components When the total amount of hexanedimethanol units exceeded 60 mol, the breaking strength of the film was lowered (Comparative Example 1), and if it was less than 30 mol, a film having sufficient heat shrinkage was not obtained (Comparative Example 2).

In addition, it can be seen that the film having the sulfonic acid metal salt derivative mixed according to the scope of the present invention has improved the antistatic property of the film without lowering the film properties such as breaking strength (Comparative Example 8) (Examples 13 to 15).

On the other hand, the film in which the hydroxyphenylbenzotriazole-based sunscreen was added according to the scope of the present invention significantly improved the UV transmittance than the film without the substance added.

As described above, the heat-shrinkable polyester film according to the present invention not only has excellent basic properties such as heat resistance, hot water resistance, chemical resistance, mechanical properties, printing characteristics, but also has low natural shrinkage at room temperature, and is uniform in thickness. Superior in heat and heat shrinkage characteristics. In addition, it is excellent in the antistatic effect can minimize the contamination by foreign matters, and by greatly reducing the UV transmittance can maintain the freshness of the contents when used for the label as well as the entire coating of the container.

Claims (13)

An aromatic dicarboxylic acid is included as an acid component repeating unit, and a trimethylene glycol unit, a tetramethylene glycol unit, a 2,2-dimethyl (-1,3-propane) diol unit and a 1,4-cyclo relative to the total diol component A heat-shrinkable polyester film comprising a diol component repeating unit having a total amount of hexanedimethanol units of 30 to 60 mol and an ethylene glycol unit of 40 to 70 mol. The heat-shrinkable polyester film of claim 1, wherein the aromatic dicarboxylic acid is at least one selected from the group consisting of dimethyl terephthalic acid, terephthalic acid, dimethylisophthalic acid, and isophthalic acid. The method of claim 1, wherein the repeating unit of the diol component is 2 to 15 moles of trimethylene glycol units, 10 to 30 moles of tetramethylene glycol units, 7 to 20 moles of 2,2-dimethyl (-1,3-propane) diol units , 1,4-cyclohexanedimethanol unit 2 to 15 moles comprising a heat-shrinkable polyester film. The sulfonic acid metal salt derivative represented by R1-SO ₃ Me (wherein R1 is an alkyl group having 5 to 20 carbon atoms and Me is an alkaline earth metal or an alkali metal) is further added in an amount of 0.01 to 1.0 weight based on the total weight of the film. A heat shrinkable polyester film, characterized in that it comprises. The heat-shrinkable polyester film of claim 4, wherein Me is a metal selected from the group consisting of lithium, sodium, potassium, and magnesium. The heat-shrinkable polyester film of claim 4, wherein the sulfonic acid metal salt derivative is at least one sulfonic acid metal salt derivative selected from the group consisting of potassium olylbenzenesulfonate, potassium nonylbenzenesulfonate and potassium undecylbenzenesulfonate. The heat-shrinkable polyester film according to claim 4, wherein the resistivity of the polyester film surface is 2 x 10 ¹³ Pa or less. The heat-shrinkable polyester film according to any one of claims 1 to 7, further comprising 0.01 to 1.0 weight of a hydroxyphenylbenzotriazole compound based on the total weight of the film. The hydroxyphenylbenzotriazole compound is a 2- [2-hydroxy-3,5-di- (1,1-diketylbenzyl) phenyl] -2H-benzotriazole. Heat shrinkable polyester film. The heat-shrinkable polyester film of claim 8, wherein the ultraviolet light transmittance of the polyester film is 30 or less based on a film thickness of 50 µm with respect to a wavelength of 345 nm. The method of claim 1, wherein the polyester film has a surface adhesiveness of at least 5B based on ASTM D3359 to nitrocellulose-based inks, the breaking strength of the film in the main shrinkage direction and its vertical direction of 18kgf / mm2, respectively. And at least 5 kgf / mm 2, thickness variation less than 5, shrinkage rate in the main shrinkage direction at 60 ° C. in hot water at 80 ° C., and shrinkage rate in the vertical direction with respect to the main shrinkage direction at less than 5 degrees. . 12. The heat-shrinkable polyester film according to claim 11, wherein the film thickness variation after 30 shrinkage in the main shrinkage direction is less than 10 in 80 DEG C hot water. The heat-shrinkable polyester film according to claim 11, wherein the natural shrinkage in the main shrinkage direction is less than 1 at 40 ° C.