KR100937315B1 - A heat shrinkable polyester film - Google Patents

Abstract

The present invention relates to a heat-shrinkable polyester film, and more specifically, it is possible to realize high shrinkage of 70% or more, and not only excellent basic properties such as shrinkage uniformity, heat resistance, printing property, solvent adhesion property, and excellent stretchability. In particular, it has excellent solvent resistance to polar solvents, so it is excellent in stability over time after printing processing, and its impact resistance in the direction of orthogonal to the main shrinkage direction is enhanced, so that the label can be cracked by external impact after labeling and heat treatment. It is low incidence, and it is possible to separate the specific gravity by the density difference with the existing PET bottle and relates to a heat-shrinkable polyester film excellent in recycling properties of the PET bottle. To this end, the heat-shrinkable polyester film according to the present invention is a heat-shrinkable polyester film uniaxially or biaxially stretched by mixing a copolymerized polyester resin and a cycloolefin copolymer, and the content of the cycloolefin copolymer is copolymer poly It is characterized in that 5 to 50% by weight based on the total weight of the ester resin and cycloolefin copolymer.

Heat-shrinkable polyester film, copolyester resin, cycloolefin copolymer

Description

Heat-shrinkable polyester film {A HEAT SHRINKABLE POLYESTER FILM}

1 is a diagram illustrating an upper curl phenomenon caused by time-dependent change after printing of a heat-shrinkable polyester film

<Brief description of symbols for the main parts of the drawings>

1: Upper curl phenomenon

The present invention relates to a heat-shrinkable polyester film, and more specifically, it is possible to realize high shrinkage of 70% or more, and not only excellent basic properties such as shrinkage uniformity, heat resistance, printing property, solvent adhesion property, and excellent stretchability. In particular, it has excellent solvent resistance to polar solvents, so it is excellent in stability over time after printing processing, and its impact resistance in the direction of orthogonal to the main shrinkage direction is enhanced, so that the label can be cracked by external impact after labeling and heat treatment. It is low incidence, and it is possible to separate the specific gravity by the density difference with the existing PET bottle and relates to a heat-shrinkable polyester film excellent in recycling properties of the PET bottle.

In general, heat shrinkable films are widely used for labeling plastic bottles, glass bottles, cap-seal, battery packaging, and directly packaging several containers by using shrinkage properties by heating. . In order to use the heat-shrinkable film for various packaging materials or labels, the heat-shrinkable film should have excellent sealing properties, uniformity of shrinkage, etc. as well as basic properties such as heat resistance, chemical resistance, weather resistance, and printing characteristics.

Such heat-shrinkable films are conventionally polyvinyl chloride-based, polystyrene-based, polypropylene-based, polyethylene-based, etc., polyvinyl chloride-based film has a problem of very poor environmental friendliness due to problems such as chlorine gas and dioxin generation during incineration. . Due to low temperature shrinkage and low shrinkage rate, polystyrene film can achieve uniform shrinkage after shrinkage, and the appearance of good shrinkage can be highly evaluated. However, since solvent resistance is poor, a special composition ink must be used for printing. Rather, there is a problem that the natural shrinkage is difficult to store large. Polypropylene films are poor in shrinkage at low temperatures, and wrinkles and stains tend to occur in the shrinkage portions. In addition, the above films have a disadvantage in that heat resistance is insufficient, and it is difficult to maintain a film state because it is easy to melt or rupture at the time of the boy treatment or the retort treatment.

In recent years, studies on polyester films without such problems have been actively conducted, and are expected as a shrink label to replace polyvinyl chloride films and polystyrene films, and as the usage of PET containers increases, It is also increasing.

The heat-shrinkable polyester film generally used is polyethylene terephthalate, which is excellent in heat resistance and weather resistance, but polyethylene terephthalate alone is excellent in dimensional stability to obtain a sufficient heat shrinkage rate and excessively high shrinkage stress. There is a problem that the shrinkage rate is too fast. In order to solve this problem, Japanese Patent Application Laid-Open No. 57-42726, Japanese Patent Application Laid-Open No. 57-159510, Japanese Patent Application Laid-Open No. 59-97175, or the like, may be blended with polyethylene terephthalate or polybutylene terephthalate at a constant ratio. Shrinkage by copolymerizing dicarboxylic acid components of terephthalic acid and isophthalic acid with diol components such as ethylene glycol and 1,4-cyclohexanedimethanol, propanediol, diethylene glycol and triethylene glycol It is proposed that uniformity and the like can be improved.

However, although the shrinkage uniformity may be improved to some extent, such copolyester-based films may have a low impact resistance due to excessive heat treatment in the domestic user process of high temperature labeling and hot beverage filling, and impacts of the containers during transportation in the finished state. There is a problem that is easily ruptured by, and the solvent resistance to polar solvents such as toluene, methyl ethyl ketone, ethyl acetate used as a printing solvent is poor, shrinkage due to the change over time after a certain time by the residual solvent after printing There is a problem that the incidence of poor finishability is increased. In addition, the polyester-based heat-shrink film of the same material in the recycling of PET bottles has a disadvantage in that the specific gravity is difficult to separate and the recycling property is poor.

The present invention has been made to solve the above problems, the object of the present invention is to improve the mechanical properties such as tensile strength, elongation in the longitudinal direction (length direction) after the labeling and hot beverage filling process finished product state after labeling No bursting failure due to impact, and excellent solvent resistance to polar solvents used as printing solvents, almost no shrinkage and finishing properties due to changes over time even after a certain time after printing, and also with PET bottles and shrink labels It is to provide a heat-shrinkable polyester film excellent in the recycling property of the PET bottle by the specific gravity separation is possible.

The above and other objects and advantages of the present invention will become more apparent from the following description of the preferred embodiments with reference to the accompanying drawings.

The heat-shrinkable polyester film according to the present invention for achieving the above object is a heat-shrinkable polyester film uniaxially or biaxially stretched by mixing a copolyester resin and a cycloolefin copolymer, The content is characterized in that 5 to 50% by weight based on the total weight of the copolyester resin and cycloolefin copolymer.

Preferably, the copolyester resin is dimethyl terephthalate, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic 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 sulfide Poisophthalic acid, trimellitic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, pimeric acid, azelaic acid, pyromellitic acid, 1,4-cyclohexanedicarboxylic acid and 1,3-cyclohexanedicarboxylic acid 50 to 90 mol% of ethylene glycol and neopentyl glycol, 1,4-cyclohexanedimethanol, diethylene glycol, propanediol, and the first component of dicarboxylic acid consisting of a single or a mixture thereof selected from the group consisting of acids Diol consisting of 10 to 50 mol% of a single or mixture thereof selected from the group consisting of butanediol The second component is a copolymerized resin.

More preferably, the copolyester resin is 50 to 90 mol% of ethylene glycol and 1,4-cyclohexanedimethanol, the first component of dicarboxylic acid consisting of a single or a mixture thereof selected from dimethyl terephthalate or terephthalic acid. Characterized in that the second component of the diol consisting of 10 to 50 mol% is a copolymerized resin.

Also preferably, the glass transition temperature (Tg) of the cycloolefin copolymer is characterized in that 60 to 80 ℃.

Also preferably, the heat-shrinkable polyester film has a density of 1.25 g / cm 3 or less.

Also preferably, the heat-shrinkable polyester-based film is characterized in that the top curl failure rate is less than 10% at labeling even after 45 days after printing,

Also preferably, the heat-shrinkable polyester film has a tensile strength of 5 kg _f / mm 2 or more and a tensile elongation of 50% or more in a direction perpendicular to the main shrinkage direction after 10% heat shrink and heat treatment.

Also preferably, the heat-shrinkable polyester film is characterized in that the shrinkage measured after immersing in 90 ℃ hot water for 10 seconds at least 70% in one direction.

Also preferably, the heat-shrinkable polyester film has a haze of less than 10%.

Also preferably, the heat-shrinkable polyester film is characterized in that the fusion start temperature of the film exceeds 120 ℃.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings of the present invention. These examples are only presented by way of example only to more specifically describe the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples. .

The heat-shrinkable polyester film according to the present invention is a heat-shrinkable polyester film obtained by mixing a copolyester resin and a cycloolefin copolymer and uniaxially or biaxially stretching the film, wherein the content of the cycloolefin copolymer is copolyester resin. And the cycloolefin copolymer is characterized in that 5 to 50% by weight based on the total weight.

The copolymerized polyester resin of the heat-shrinkable polyester film according to the present invention is characterized in that the first component of the dicarboxylic acid and the second component of the diol are produced by copolymerization.

The first component of the dicarboxylic acid is dimethyl terephthalate, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic 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, oxalic acid, malonic acid, succinic acid, glutaric acid, pimeric acid, azelaic acid, pyromellitic acid, 1,4-cyclohexanedicarboxylic acid and 1,3-cyclohexanedica Selected from the group consisting of carboxylic acids or a mixture thereof, and the second component of the diol is 50 to 90 mol% of ethylene glycol components and neopentyl glycol, 1,4-cyclohexanedimethanol, diethylene glycol, propanediol , Butanediol is preferably selected from the group consisting of 10 to 50 mol% alone or a mixture thereof.

More preferably, 50 to 90 mol% of the first component and ethylene glycol component and 10 to 50 mol% of 1,4-cyclohexanedimethanol of the dicarboxylic acid consisting of a single or a mixture thereof selected from dimethyl terephthalate or terephthalic acid. The 2nd component of the formed diol is 1, 4- cyclohexane dimethanol copolymerized polyester resin. When the content of 1,4-cyclohexanedimethanol in the diol component is less than 10 mol%, the dimensional stability of the copolyester is increased, so that it is difficult to realize a sufficient heat shrinkage rate, the shrinkage rate and the shrinkage stress are too high, so that the shrinkage finish If there is a problem of falling and the content of 1,4-cyclohexanedimethanol is more than 50 mol%, it is difficult to crystallize the chips produced, and the chips are fused in raw material drying process to prevent hydrolysis, which may cause process trouble. Can be. The intrinsic viscosity of the 1,4-cyclohexanedimethanol copolyester is preferably 0.60 to 0.80.

The heat-shrinkable polyester film according to the present invention is characterized in that it comprises a cycloolefin copolymer with the copolyester as a main component.

The heat shrinkable polyester film according to the present invention includes a cycloolefin copolymer, so that the mechanical properties in the main shrinkage direction and the orthogonal direction are excellent, so that the label is ruptured by external impact during transportation in the finished product state after the labeling and hot beverage filling process. Not only the defect rate is remarkably lowered, but also the solvent resistance to the polar solvent used as the printing solvent is excellent, so that the shrinkage finish defect due to the change over time after the printing is hardly generated. In addition, the cycloolefin copolymer has an advantage that the specific gravity is lower than that of the polyester, so that when a certain amount is included, specific gravity separation is possible when recycling the PET bottle due to the specific gravity difference with the PET bottle.

The heat-shrinkable polyester film according to the present invention is characterized in that it comprises 5 to 50% by weight of the cycloolefin copolymer with respect to the total weight of the copolymerized polyester resin and cycloolefin copolymer, the content of the cycloolefin copolymer If it is less than 5% by weight, the effect of improving impact resistance and solvent resistance cannot be expected, and if it exceeds 50% by weight, it is difficult to realize a high shrinkage of 70% or more. This problem occurs because the fall, there is a problem that the adhesive properties are not expressed for a solvent such as THF or 1,3-Dioxolane used as an adhesive of the existing heat-shrinkable polyester film.

The cycloolefin copolymer is a copolymer of ethylene and norbornene made by using a metallocene catalyst having a property of improving physical properties. The cycloolefin copolymer can be molded by various methods such as melt extrusion or injection, and can be molded within various temperature ranges by thermal deflection. These cycloolefin copolymers have excellent transparency, high resistance to polar solvents, high toughness and strength, and when included in a certain amount or more, weaknesses of existing heat-shrinkable polyesters can be improved. have.

The cycloolefin copolymer has a glass transition temperature (Tg) of 60 to 80 ° C. in order to increase compatibility with 1,4-cyclohexanedimethanol copolyester during the melt extrusion process for producing a heat-shrinkable polyester film. A melt extrusion temperature of 230 to 300 ° C. is suitable, and a commercially available cycloolefin copolymer is Topas ^® 9506F, model name of Topas, Germany. The cycloolefin copolymer has a glass transition temperature of 65 ° C. and an appropriate melt extrusion temperature of 230 to 240 ° C., and has a similar melting behavior to that of 1,4-cyclohexanedimethanol copolyester. When the cycloolefin copolymer is added within the content range, it is possible to improve the impact resistance after labeling by improving mechanical and structural properties in the opposite direction of stretching in a uniaxial stretching process for producing a heat-shrinkable polyester film. Excellent solvent resistance to the polar solvent to be used, it is possible to improve the shrinkage finish failure due to the change over time even after a certain time after printing. In addition, the specific gravity of the heat shrinkable film may be reduced to allow separation of specific gravity when recycling PET bottles.

In addition, the heat-shrinkable polyester film according to the present invention may further add a polymerization catalyst, a dispersant, an electrostatic agent, and other lubricants within a range that does not impair the effects of the invention.

The heat-shrinkable polyester film according to the present invention can be formed into a film by selecting any method such as a casting method or a calendering method using a composition including the above components. Specifically, the above-described 1,4-cyclohexanedimethanol copolyester polyester and cycloolefin copolymer are dried, melt-mixed at a temperature of 230 to 300 ° C., and then extruded to prepare a melt sheet, and then the sheet is cooled and solidified. The obtained sheet can be uniaxially or biaxially stretched at a temperature of the glass transition temperature (Tg) or more by the tenter method to obtain a film. In the stretching step, stretching at 3.0 to 7.0 times, preferably 3.5 to 5.0 times, can obtain sufficient heat shrinkage of the film.

In addition, it is preferable that the heat-shrinkable polyester film according to the present invention has a thickness of 12 to 125 μm, and has excellent stretch uniformity, so that there is no particular thickness restriction in manufacturing the film.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples are only examples of the present invention and the present invention is not limited thereto.

EXAMPLE

Production Example  One

100 mole parts of dimethyl terephthalate as the dicarboxylic acid component, 130 mole parts of ethylene glycol as the diol component and 20 mole parts of 1,4-cyclohexanedimethanol were added to an autoclave equipped with a stirrer and a distillation column, and manganese acetate as a transesterification catalyst. Was added 0.07% by weight relative to dimethylterephthalate. Thereafter, the reaction was carried out while raising the temperature to 240 ° C. and removing the metalol from the reaction. After the completion of the ester exchange reaction, 0.03% by weight of trimethyl phosphate was added to dimethyl terephthalate as a heat stabilizer. After 5 minutes, 0.04% by weight of antimony trioxide was added as a polymerization catalyst and stirred for 5 minutes. Subsequently, the mixture was transferred to a second reactor equipped with a vacuum facility, and then gradually reduced in pressure while heating up at 280 ° C. to polymerize for about 4 hours to obtain 1,4-cyclohexanedimethanol copolymerized polyester (polymer A) having an intrinsic viscosity of 0.70.

Production Example  2

1,4-cyclohexanedimethanol copolymer polyester having an extreme viscosity of 0.70 in the same manner as in Preparation Example 1, except that the content of 1,4-cyclohexanedimethol was changed to 40 mol parts in Preparation Example 1. B) was obtained.

Example  1 to 4 and Comparative example  1 to 4

The polymers A and B obtained in Preparation Examples 1 and 2 were mixed with the cycloolefin copolymer in the ratios shown in Table 1 below, melted at 250 ° C., extruded from a T-die, and then subjected to a grade by casting or calendering. Cooling gave an unstretched sheet. The unstretched sheet obtained by performing the stretching process 3.0 times to 7.0 times at a temperature of glass transition temperature to glass transition temperature + 30 ℃ to obtain a heat shrink film having a thickness of 50㎛.

Table 1 below shows the blending ratio, stretching temperature, film forming conditions and stretching ratio of each polymer constituting the heat-shrinkable polyester film prepared according to Examples 1 to 4 and Comparative Examples 1 to 4.

TABLE 1

Polymer blending ratio Production temperature Elongation ratio Polymer A Polymer B COC Preheating temperature Drawing temperature Heat-set temperature Bell Lateral Example 1 80 0 20 85 80 60 1.0 4.0 Example 2 60 0 40 85 80 60 1.0 4.0 Example 3 0 80 20 85 80 60 1.0 4.0 Example 4 0 60 40 85 80 60 1.0 4.0 Comparative Example 1 97 0 3 85 80 60 1.0 4.0 Comparative Example 2 0 100 0 85 80 60 1.0 4.0 Comparative Example 3 40 0 60 85 80 60 1.0 4.0 Comparative Example 4 0 0 100 85 80 60 1.0 4.0 Polymer A: 1,4-cyclohexanedimethanol copolymerized polyester (1,4-cyclohexanedimethanol content: 20 mol%) Polymer B: 1,4-cyclohexanedimethanol copolymerized polyester (1,4-cyclohexane Dimethanol content: 40 mol%) COC: cycloolefin copolymer

[ Experimental Example ]

1. Heat shrinkage measurement

The film was cut into 10 cm x 10 cm squares, immersed for 10 seconds in a hot water maintained at a temperature of 90 DEG C without load, and then the length was measured to determine the heat shrinkage rate according to the following equation.

Thermal contraction rate (%) = 100 × (length before shrinkage-length after shrinkage) / (length before shrinkage)

2. 10% shrinkage (heat treatment) and after heat treatment Main contraction direction  Evaluation of Mechanical Properties in Orthogonal Directions

In order to evaluate the mechanical properties after the heat treatment, using a United tensile strength tester (model SSTM-5KN) equipped with a chamber (chamber), 15cm in the main shrinkage direction and 15 in the main shrinkage direction After cutting to mm, loosely mount the specimen so that the length of the specimen (11.1 cm) and the length of the chuck and the chuck (10 cm) are 0.9. Thereafter, the temperature of the chamber is heated to 120 ° C. and then maintained for 10 seconds to allow 10% heat shrinkage of the mounted specimen. The heat-shrink film is again maintained for 30 minutes after cooling the chamber temperature to 90 ℃. Then, after cooling the temperature of the chamber to room temperature again, a tension-strain curve was obtained until the fracture occurred while stretching at a rate of 100 mm / min. At this time, the tensile force (kg _f / mm 2) when breaking occurred was set as the tensile strength, and the length ratio (%) to increase until breaking occurred as tensile elongation.

3. Evaluation of Tightness after Printing

The film was printed 3 degrees with green, red, and white ink containing toluene, methyl ethyl ketone, and ethyl acetate at 4: 4: 2, and then both ends were sealed with 1,3-Dioxolane and 152 mm wide and 130 mm long. Cylindrical labels were prepared such that both ends 5 mm in the length direction were left unprinted. The label was placed on a shoulder and torso of a commercially available 1.5L square PET bottle after storing for 30 days and 45 days in a thermo-hygrostat (model TH-G) maintained at a temperature of 35 ° C. and a humidity of 70%. Labeled in the tunnel. The hot air tunnel was labeled with line speed 130 BPM (bottle per minute) at a shrink tunnel condition of 180 ° C./190° C./200° C. using a labeler with the name SSI-2503 of Shinsung Eng. The number of labeling was carried out 200 times, of which 1 is defined as the shrinkage finish failure when the upper end of the label is rolled inward, as shown in Figure 1, and evaluated the shrinkage failure rate (%) due to changes over time after printing.

4. Evaluation of heat resistance of film (blocking resistance)

Cut the film to 210mm in the main shrinkage direction and 297mm in the orthogonal direction to the main shrinkage direction, and then overlap the two sheets using a laminator (GMP G, 320, Model GHP320) at 10 ° C intervals from 10 ° C to 70 ° C to 150 ° C. Lamination was carried out at a rate of / sec and then the presence or absence of fusion of the film surface was confirmed. The temperature at which the film was fused was checked and evaluated according to the following criteria.

◎: fusion occurs at a temperature exceeding 120 ° C

(Circle): Fusion generate | occur | produces at the temperature of 100 degreeC or more and 120 degrees C or less.

Х: Fusion occurs at temperatures below 100 ° C

5. Solvent Adhesion Evaluation

Solvent 1,3-Dioxolane or THF (tetrahydrofuran) is applied to the surface of the film at intervals of 5 mm in the direction perpendicular to the main shrinkage direction and bonded. After standing for 1 hour, cut to 15mm width in the main shrinkage direction, and tested the T-peel strength at a test speed of 100mm / min using a tensile tester (Model SSTM, United). It was.

◎: film is stretched or broken before adhesive part peels off

○: adhesive strength of 3.0 N / 15 mm or more

Х: adhesive strength less than 3.0 N / 15 mm

6. Evaluation of printing characteristics

After applying the nitrocellulose-based ink to the film surface, a lattice pattern was formed on the coated surface of the film at regular intervals using a laser blade. Subsequently, when the 3M company 610M Scotch tape was adhered to the coated surface of the film and then rapidly removed, the transfer degree of the ink was checked on the tape adhesive surface, and evaluated as follows.

◎: 0% ink transfer rate for 3M tape

○: less than 30% ink transfer rate for 3M tape

Х: Over 30% ink transfer rate for 3M tapes

7. Haze measurement

After the film was manufactured, the haze value was measured according to ASTM D 1003 using a haze measuring instrument (Model NDH-300A, Nippon Denshoku Kogyo Co., Ltd.), and evaluated according to the following criteria.

◎: less than 5% of haze

○: more than 5% haze is less than 10%

Х: 10% or more haze

8. Density Determination

Density meter is measured using DC-4 type measuring instrument of TECHNE of UK, standard ball for density measurement, and density gradient shown below. Prepare the measuring gradient in the density tester, and use the standard ball to determine the density value according to the position of the density tester. The sample is cut into squares of 5mm in width and length, and then immersed in the density gradient, and the density meter is read and calculated according to the following formula.

 Y = AX + B

Where Y = density, X = slope, A = sample height (standard ball height), and B = intercept.

Density gradient Carbon tetrachloride (CCI ₄ ) with a density of 1.5998 g / cm 3 and n-heptane (CH ₃ (CH ₂ ) ₅ CH ₃ ) with a density of 0.6800 g / cm ₃ Use after mixing the appropriate amount to prepare the instrument drainage.

The heat-shrinkable polyester films prepared according to Examples 1 to 4 and Comparative Examples 1 to 4 were subjected to performance evaluation as a heat shrinkable film, and the results are shown in Table 2 below. In Table 2, the unit of strength is "kg _f / mm2" and the elongation is "%".

TABLE 2

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Heat Shrinkage (%) MD One One One One 2 2 One One TD 76 78 75 78 73 73 75 75 Mechanical Properties (MD, Before Heat Treatment) burglar 8.6 9.7 8.3 9.4 6.3 6.1 10.6 12.5 Shinto 540 520 540 520 580 580 480 450 Mechanical Properties (MD, After Heat Treatment) burglar 8.2 9.1 8.0 9.0 5.2 5.0 10.5 12.3 Shinto 520 510 530 510 Side payment Side payment 480 450 Time-lapse stability after printing (% defective rate) 30 days 0 0 0 0 15 21 0 0 45 days One 0 2 0 26 35 One 0 Heat resistance ◎ ◎ ◎ ◎ ○ ○ ◎ ◎ Solvent Adhesion ◎ ○ ◎ ○ ◎ ◎ Х Х Printing characteristics ◎ ○ ◎ ◎ ◎ ◎ Х Х Haze ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ density 1.24 1.19 1.22 1.17 1.30 1.31 1.13 1.02 TD: Transverse direction (main contraction direction) MD: Longitudinal direction (perpendicular direction and orthogonal direction) Side payment: Unavailable

Referring to Table 2, the heat-shrinkable polyester film of Examples 1 to 4 prepared according to the present invention is capable of realizing a high shrinkage of 70% or more, and even after a certain period of time after printing, the shrinkage finish poor due to changes over time It is hardly generated and shows excellent stability over time after the printing process compared to the existing heat-shrinkable polyester film, and also has excellent mechanical properties even after labeling and heat treatment due to enhanced impact resistance in the main shrinkage direction and orthogonal direction. In addition, it is possible to provide an excellent heat-shrinkable polyester film that can be separated by specific gravity due to density differences with existing PET bottles.

Although the present invention has been described in detail with reference to only a few embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the present invention, and such changes and modifications are within the scope of the appended claims.

According to the heat-shrinkable polyester film according to the present invention, high shrinkage of 70% or more can be realized and the basic properties such as shrinkage uniformity, heat resistance, printing property, solvent adhesion property, and excellent stretchability, in particular, polarity Excellent solvent resistance to solvents, excellent stability over time after printing process, impact resistance in the direction of main contraction and orthogonality is strengthened, and the rate of cracking of the label due to external impact after labeling and heat treatment is low. In addition, the specific gravity can be separated by the density difference with the existing PET bottle, and the recycling property of the PET bottle is excellent.

Therefore, the heat-shrinkable polyester film according to the present invention is useful for labeling and coating containers having improved conventional problems.

Claims (10)

In the heat-shrinkable polyester film, As a heat-shrinkable polyester film obtained by mixing a copolyester resin and a cycloolefin copolymer and stretching uniaxially or biaxially, The cycloolefin copolymer may be contained in an amount of 5 to 50 wt% based on the total weight of the copolyester resin and the cycloolefin copolymer. The copolyester resin is 50 to 90 mol% of ethylene glycol and 10 to 50 mol% of ethylene glycol and the first component of dicarboxylic acid consisting of a single or a mixture thereof selected from dimethyl terephthalate or terephthalic acid. Heat-shrinkable polyester film, characterized in that the second component of the diol consisting of a copolymerized resin. delete delete The method of claim 1, The glass transition temperature (Tg) of the cycloolefin copolymer is 60 to 80 ℃, heat shrinkable polyester film. The method according to claim 1 or 4, The heat-shrinkable polyester film is a heat-shrinkable polyester film, characterized in that the density is 1.25g / cm 3 or less. The method according to claim 1 or 4, The heat-shrinkable polyester film is a heat-shrinkable polyester film, characterized in that the top curl failure rate is 10% or less at the time of labeling even after 45 days after printing. The method according to claim 1 or 4, The heat-shrinkable polyester film is a heat-shrinkable polyester film, characterized in that the tensile strength in the orthogonal direction and the main shrinkage direction 5kg _f / ㎜ or more, and tensile elongation 50% or more after 10% heat shrink and heat treatment. The method according to claim 1 or 4, The heat-shrinkable polyester film is a heat-shrinkable polyester film, characterized in that the shrinkage measured after immersing in 90 ℃ hot water for 10 seconds is at least 70% in at least one direction. delete The method according to claim 1 or 4, The heat-shrinkable polyester film is a heat shrinkable polyester film, characterized in that the fusion start temperature of the film exceeds 120 ℃.

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