KR20120043312A - Uv-absorbable and heat shrinkable polyester film and preparation method thereof - Google Patents

Abstract

PURPOSE: A UV-absorbing polyester-based heat-shrinkable film is provided to have excellent UV absorption, to effectively protect contents against UV, and to have excellent strength and labeling property along longitudinal direction of film which is main contraction detection. CONSTITUTION: A UV-absorbing polyester-based heat-shrinkable film comprises ethylene terephthalate base repeating unit and UV absorber. Optical transmittance in wavelength of 360 nm or less is 10% or less, optical transmittance in wavelength of 400nm is 60% or more, haze is 10 or less, contraction ratio along longitudinal direction, which is main contraction direction, after keeping in hot water of 90 °C for 10 seconds is 20% or less, and contraction ratio coefficient along longitudinal direction is 2.5-4.

Description

UV absorbing polyester heat shrink film and manufacturing method thereof {UV-ABSORBABLE AND HEAT SHRINKABLE POLYESTER FILM AND PREPARATION METHOD THEREOF}

The present invention relates to a polyester heat-shrink film having excellent ultraviolet absorbency and suitable for high functional packaging applications such as medical ampoules and cosmetics, and having excellent mechanical strength and labeling property in the longitudinal direction of the film in the main shrinkage direction, and a manufacturing method thereof. .

Heat-shrinkable films are generally used for various purposes such as labeling of plastics, glass bottles, batteries or electrolytic capacitors, and whole coatings of packaging containers, as well as for packaging or tight packaging for stationery or several containers. As such a heat-shrinkable film, a polyvinyl chloride film, a polystyrene film, a polypropylene film, and the like are used, and in recent years, many polyester films are also used.

In order to be used for various packaging materials or labels, polyester-based heat-shrinkable films are not only basic properties such as heat resistance, chemical resistance, weather resistance, and printing characteristics, but also container sealing properties, heat shrink uniformity, running characteristics and crack resistance in the longitudinal direction, etc. Is required.

However, conventional polyester heat-shrink films used for labels or coatings have a non-stretched longitudinal direction because the main stretching direction is the width direction rather than the longitudinal direction of the roll, and thus is mainly contracted in the stretched width direction. Mechanical properties were structurally weak. That is, in the conventional heat shrink film, since the main shrinkage direction is in the width direction (lateral direction), the strength in the longitudinal direction is low in the winding or post-processing process, so that the running characteristic in the longitudinal direction is remarkably broken, such as being easily broken even in the slight tension change. fell.

Therefore, recently, many techniques for producing a film shrinking in the longitudinal direction by using a polyester containing a dicarboxylic acid component and a diol component have been reported (for example, Republic of Korea Patent No. 517064).

In this regard, in the case of a packaging film used in a small container, a pressure-sensitive adhesive is applied to the longitudinal heat-shrink film to apply hot air to shrink the label or to cover the entire container lid. However, the label shrinkage phenomenon occurs when exposed to high temperatures in the distribution process, the heat shrink film used should have a low shrinkage at a relatively low temperature of 60 ~ 70 ℃. In addition, high shrinkage of 65% or more is required for full wrapping.

On the other hand, when drugs or cosmetics are exposed to ultraviolet rays, the contents of the contents or the shelf life of the contents are often shortened. Accordingly, special care is required during distribution and use, and the improvement of fundamental packaging problems is urgently needed than such handling precautions.

Accordingly, an object of the present invention is to provide a polyester-based heat shrink film having excellent ultraviolet absorption and excellent mechanical strength and labeling property in the longitudinal direction of a film which is a main shrinkage direction, and a method of manufacturing the same.

In order to achieve the above object,

(i) comprising an ethylene terephthalate main repeating unit and an ultraviolet absorber,

(ii) a light transmittance of 10% or less at a wavelength of 360 nm or less and a light transmittance of 60% or more at a wavelength of 400 nm,

(iii) the haze is less than 10,

(iv) The shrinkage in the longitudinal direction, which is the main shrinkage direction of the film, after holding for 10 seconds at 90 ° C. hot water for at least 65%, and the shrinkage in the longitudinal direction, which is the main shrinkage direction of the film, after holding for 10 seconds at 70 ° C. Hereinafter, provides a polyester-based heat shrink film characterized in that the longitudinal shrinkage gradient constant (S) is 2.5 to 4 defined by the following equation (1):

Where

S ₇₀ is the shrinkage rate in the longitudinal direction, which is the main shrinkage direction of the film after holding for 10 seconds in 70 ℃ hot water,

S ₈₀ is the shrinkage rate in the longitudinal direction which is the main shrinkage direction of the film after holding for 10 seconds in 80 ℃ hot water,

S ₉₀ is the shrinkage rate in the longitudinal direction, which is the main shrinkage direction of the film, after holding for 10 seconds at 90 ° C. hot water.

The present invention also provides

(1) melting and extruding a polyester film-forming composition comprising an ethylene terephthalate main repeating unit and an ultraviolet absorber at a temperature of 220 to 285 ° C. to produce a molten sheet;

(2) cooling and solidifying the melt sheet to produce a cooled solidified polyester unstretched sheet; And

(3) drawing the unstretched sheet at a total draw ratio of 3.5 to 4.5 times the longitudinal direction of the sheet;

It provides a method for producing a polyester-based heat shrink film.

The ultraviolet absorbent polyester heat shrinkable film according to the present invention has excellent ultraviolet absorbency to effectively protect the contents from ultraviolet rays, and has excellent mechanical strength and labeling property in the longitudinal direction of the film in the main shrinkage direction, and thus high functional packaging such as medical ampoules or cosmetics. This can be very useful for.

Polyester-based heat-shrink film according to the present invention is a film shrinking in the longitudinal direction, comprising (i) an ethylene terephthalate main repeating unit and an ultraviolet absorber, (ii) light transmittance of 10% or less at a wavelength of 360nm or less and 400nm Light transmittance at wavelength is 60% or more, (iii) haze is less than 10, and (iv) the shrinkage in the longitudinal direction, which is the main shrinkage direction of the film, is maintained at 65 ° C. or more after holding for 10 seconds at 90 ° C. hot water, and 70 ° C. hot water. After maintaining for 10 seconds in the longitudinal shrinkage in the longitudinal direction of the film is 20% or less, characterized in that the longitudinal shrinkage gradient constant (S) is 2.5 to 4 defined by the formula (1).

Conventional widthwise heat-shrink film is a heat shrinkage property through the heat treatment in the tenter by using the tenter method, whereas the polyester film according to the present invention is a shrinkage film in the longitudinal direction, the specific stretching temperature and draw ratio By controlling the shrinkage at 70 ℃, 80 ℃, and 90 ℃ through a low shrinkage at a relatively low temperature 70 ℃, high shrinkage at a relatively high temperature 90 ℃ to prevent the spread of labels that occur frequently when exposed to high temperatures Not only does it do, but it also enables full wrapping.

In particular, the polyester-based heat shrink film according to the present invention must be stretched in the longitudinal direction at a high draw ratio of 3.5 to 4.5 times to induce stretch crystallization in order to achieve heat shrink properties in accordance with the object of the present invention.

In addition, the polyester-based heat-shrink film according to the present invention may be stretched under a specific temperature condition in order to achieve the heat-shrinkage properties in accordance with the object of the present invention, the machine direction stretching portion is drawn in the longitudinal direction due to the circumferential speed difference between the rolls It can be divided into a preheating part, a drawing part and a cooling part. In the preheating part, the unstretched sheet gradually rises to a temperature for stretching while running the roll. The temperature of the preheating part is 65 to 80 ° C., preferably 70 to 75 ° C., which is suitable near the glass transition temperature. If the temperature is set higher, the shrinkage ratios of 70 ° C and 80 ° C change, so that the desired shrinkage curve cannot be obtained. The stretching section is a section in which stretching occurs at an actual circumferential speed, and the stretching section has a temperature of 75 to 90 ° C., preferably 80 to 85 ° C., and a glass transition temperature of +5 to 10 ° C. is suitable. When the temperature is set lower, cold stretching may occur and cloudiness may occur after stretching, and when the temperature is set higher, roll adhesion may occur and the transparency of the film after stretching may decrease. In the drawing unit, a radiator heater is used to compensate for the insufficient heat, and the temperature of the heater is 300 to 500 ° C, preferably 400 to 450 ° C. If the temperature is set higher, the shrinkage of 90 ° C. is reduced. The cooling unit is a portion where the film is cooled as it passes through the roll after stretching, and the temperature of the cooling unit should be 50 to 25 ° C. so that the stretched film can be gradually cooled to room temperature.

Accordingly, the polyester film according to the present invention has a shrinkage rate of 65% or more in the longitudinal direction, which is the main shrinkage direction of the film, after holding for 10 seconds at 90 ° C. hot water, and main shrinkage of the film after holding for 10 seconds at 70 ° C. hot water. Direction shrinkage in the longitudinal direction is 20% or less, and shows a heat shrinkage characteristic in which the longitudinal shrinkage gradient constant (S) is 2.5 to 4, which is defined by Equation 1 below:

[Equation 1]

S = (S ₈₀ -S ₇₀ ) / (S ₉₀ -S ₈₀ )

Where

S ₇₀ is the shrinkage rate in the longitudinal direction, which is the main shrinkage direction of the film after holding for 10 seconds in 70 ℃ hot water,

S ₈₀ is the shrinkage rate in the longitudinal direction which is the main shrinkage direction of the film after holding for 10 seconds in 80 ℃ hot water,

S ₉₀ is the shrinkage rate in the longitudinal direction, which is the main shrinkage direction of the film, after holding for 10 seconds at 90 ° C. hot water.

In addition, the polyester film shows excellent mechanical strength, the breaking strength in the longitudinal direction is 20 kgf / mm ² or more, the elongation at break in the longitudinal direction is less than 80%.

The heat-shrinkable polyester film according to the present invention having the above characteristics includes ethylene terephthalate as a main repeating unit, specifically 60 to 97 mol% of ethylene terephthalate repeating units; And a polyester resin comprising 3 to 40 mol% of repeating units derived from an acid component such as terephthalic acid, naphthalenedicarboxylic acid or a mixture thereof and a branched alkylene glycol component having 3 or more carbon atoms.

The polyester resin used in the heat-shrinkable polyester-based film according to the present invention includes a repeating unit derived from an acid component such as terephthalic acid, naphthalenedicarboxylic acid or a mixture thereof and a branched alkylene glycol component having 3 or more carbon atoms. When incorporated into the substrate, a sharp increase in stretch crystallization may result in insufficient toughness in the main shrinkage direction, causing cracking, or excessively inhibiting the crystallinity of the film, thereby lowering heat resistance, or heat in hot filling, high temperature sterilization, and retort processing. There is no fear that a hole is formed in the label.

Ethylene terephthalate as the main repeating unit is derived from dicarboxylic acid and glycol. Examples of the dicarboxylic acid include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and orthophthalic acid; Aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid; Alicyclic dicarboxylic acid; And esterified products thereof. Ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, etc. may be used as the glycol.

Specific examples of the branched alkylene glycol having 3 or more carbon atoms include 1,2-octanediol, 1,3-octanediol, 2,3-butanediol, 1,3-butanediol, 2,2-dimethyl-1,3-propane Diol (neopentyl glycol), 2-butyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,1-dimethyl-1,5-pentanediol, and mixtures thereof.

The heat-shrinkable polyester film according to the present invention includes an ultraviolet absorber, and in the present invention, a low molecular weight ultraviolet absorber is suitable, and specific examples thereof include salicylic acid type, benzotriazole type, benzophenone type, cyanoacrylate type compound, and the like. And mixtures thereof. The film of the present invention may comprise 0.2 to 0.7% by weight, preferably 0.3 to 0.5% by weight of the ultraviolet absorber based on the total weight of the film. If the content of the UV absorber is less than 0.2% by weight, the light transmittance at 360 nm or less is greater than 10%, and the UV absorption rate is lowered. Absorbs light), the film tends to be yellowish. Therefore, when it is out of this content range, it is difficult to satisfy the light transmittance, that is, the ultraviolet absorbency as described above.

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

It is preferable that the heat-shrinkable polyester film which concerns on this invention is 12-75 micrometers in thickness. When the film has a thickness in the above range, the stretching uniformity is excellent, and when used for labels or packaging, the heat shrink uniformity, ink adhesion, moisture and gas barrier properties, crack resistance, fracture resistance and the like are excellent.

The heat-shrinkable polyester film according to the present invention comprises (1) melting and extruding a polyester film-forming composition containing an ethylene terephthalate main repeating unit and an ultraviolet absorber at a temperature of 220 to 285 ° C. to form a molten sheet. Manufacturing; (2) cooling and solidifying the melt sheet to produce a cooled solidified polyester unstretched sheet; And (3) stretching the unstretched sheet at a total draw ratio of 3.5 to 4.5 times the longitudinal direction of the sheet.

The polyester-based film-forming composition includes an ethylene terephthalate main repeating unit and an ultraviolet absorber, it is important to uniformly distribute the ultraviolet absorbent in the composition in order to implement the ultraviolet absorbent in accordance with the object of the present invention. To this end, it is preferable to prepare a composition for forming a polyester film by compounding an ultraviolet absorber in a polyester resin to form a master chip and then mixing with a polyester resin containing no ultraviolet absorber.

The stretching of the unstretched sheet may be carried out by a stretching method of giving a circumferential speed difference between rolls, a method of adjusting a clip spacing in the longitudinal direction of the tenter, a method of using gas pressure, etc. The stretching method in the direction is most preferred. The stretching method for giving a circumferential speed difference between rolls should be stretched in one or two or more separate sections, and in the case of stretching two or more separate sections, in particular, the circumferential speed of the rear stretching roll is It should be higher than the speed. Otherwise, necking will occur. At this time, the temperature of each of the preheating unit, the stretching unit and the cooling unit should be adjusted to the level as described above.

As described above, the longitudinal stretching method using the circumferential speed difference between the rolls in the longitudinal direction is easy to control the thickness in the width direction, and therefore, it has been required to obtain a heat shrinkable film having a good thickness in the conventional lateral stretching method. There is no need for excessive stretching or heat treatment to control shrinkage. In addition, since the film made by the stretching method satisfies the value of Equation 1, the fracture resistance is improved due to the improved crack resistance and the higher tensile strength in the longitudinal direction.

In the case of stretching the unstretched sheet, for the unstretched polyester sheet, the sum of the multi-section elongation in the longitudinal direction of the sheet is stretched 3.5 to 4.5 times, preferably 3.8 to 4.2 times, or a combination thereof is used. The film can be obtained by stretching 1.1 to 1.2 times in the width direction perpendicular to the shrinkage direction (length direction). In this case, the stretching in the width direction may be omitted.

Accordingly, the present invention also provides a label or packaging material comprising the heat-shrinkable polyester film.

When applied as a label, for example, the heat-shrinkable polyester film according to the present invention is because the main shrinkage direction is longitudinal, the process of wrapping, cutting and adhering the container while taking out the film in a continuous process after the printing process is made continuously It is possible to label simply.

As described above, the ultraviolet absorbent polyester heat-shrink film according to the present invention has excellent ultraviolet absorbency to effectively protect the contents from ultraviolet rays and has excellent mechanical strength and labeling property in the longitudinal direction of the film, which is the main shrinkage direction, for medical ampoules or cosmetics, etc. It can be very useful for high functional packaging.

Hereinafter, although an Example and a comparative example are given and demonstrated this invention, this invention is not limited to this.

Preparation Example 1: Preparation of 2,2-dimethyl-1,3-propanediol copolymer polyester (resin A)

To 100 mol parts of dimethyl terephthalate, 130 mol parts of ethylene glycol and 30 mol parts of neopentyl glycol were charged to an autoclave equipped with a stirrer and a distillation column, and 0.07% by weight of manganese acetate was added to dimethyl terephthalate as a transesterification catalyst The reaction was carried out while removing the byproduct methanol while raising the temperature to 220 ° C.

When the transesterification reaction was completed, 0.07% by weight of silica having an average particle diameter of 0.28 μm was added to dimethyl terephthalate, 0.4% by weight of trimethyl phosphate was added as a stabilizer. After 5 minutes, 0.035% by weight of antimony trioxide and 0.005% by weight of tetrabutylene titanate were added as a polymerization catalyst, followed by stirring for 10 minutes. Subsequently, the reaction product was transferred to a second reactor equipped with a vacuum equipment, and then gradually reduced in pressure while heating up to 285 ° C., and then polymerized for about 210 minutes to give 2,2-dimethyl-1,3 having an ultimate viscosity of 0.68 dL / g. Propanediol copolyester was obtained. As a result of analyzing the obtained copolymer by gas chromatography, the content of repeating units derived from 2,2-dimethyl-1,3-propanediol accounted for about 20 mol% of the total glycol component.

Preparation Example 2 Preparation of Polyethylene Terephthalate (Resin B)

The same process as in Preparation Example 1 was carried out except that 180 mol parts of ethylene glycol was used as the glycol component and 0.08 wt% of silica and 0.02 wt% of calcium carbonate were added to 100 mol parts of dimethyl terephthalate, and the ultimate viscosity was 0.72 dL / g. Phosphorus polyethylene terephthalate was obtained.

Preparation Example 3 Preparation of UV Absorbent Compounded 2,2-Dimethyl-1,3-propanediol Copolyester (Resin A ')

A master chip A 'was prepared by melt-kneading the resin A of Preparation Example 1, LA-31 (ADEKA), which is a benzotriazole-based ultraviolet absorber at 5% by weight in an extruder.

Preparation Example 4 Preparation of UV Absorber Compounded Polyethylene Terephthalate (Resin B ')

A master chip B 'was prepared by melt-kneading 10-% by weight of LA-31 (ADEKA), a benzotriazole-based ultraviolet absorber, in resin B of Preparation Example 2 in an extruder.

Examples 1 and 2, and Comparative Examples 1 to 3: Preparation of a heat shrinkable polyester film

The resins A, B, A 'and B' obtained from Production Examples 1 to 4 were mixed at the ratios shown in Table 1 below, melted at 280 ° C, extruded from a T die, and then quenched on a cooling roller to unstretched sheets. Obtained. Subsequently, in Examples 1 and 2 and Comparative Examples 2 and 3, after the obtained non-stretched sheet was heated through a heating roll at a predetermined temperature, the longitudinal stretching process was performed by the circumferential speed difference between three rolls. Was carried out to obtain a heat-shrinkable polyester film having a thickness of 50 µm mainly shrinking in the longitudinal direction. At this time, the temperature of each of the preheating unit, the stretching unit and the cooling unit was adjusted to 75, 80 and 30 ° C. In the case of Comparative Example 1, a thermally shrinkable polyester film having a thickness of 50 µm was contracted mainly in the width direction through the width direction stretching by a usual tenter method.

In Table 1 below, blending ratios (wt%) of the resins constituting the heat-shrinkable polyester films obtained from Examples 1 and 2, and Comparative Examples 1 to 3, and thus repeating unit composition ratios (mol%) and stretching ratios Presented.

After performing the performance evaluation as a heat shrinkable film about the heat-shrinkable polyester film of Examples 1 and 2 and Comparative Examples 1 to 3 as follows, the results are shown in Table 2 below.

(1) Break strength and elongation at break of the film

Measured according to ASTM D 288, the film produced using the universal testing machine (UTM, model name 6021) manufactured by INSTRON (UTM, model name 6021) was cut to about 100 mm in length, 15 mm in width, the interval between the chuck (50) It was attached so that it would be mm, and it was stretched at a tensile speed of 200 mm / min, and the breaking strength at break (kg / mm 2) and the elongation at break (%) were measured, respectively.

(2) light transmittance

Maximum light transmittance (%) at wavelengths below 360 nm and light transmittance (%) at 400 nm wavelengths were measured using a UV / Vis Spectrophotometer (JASCO V530), respectively.

(3) 70 ℃ / 80 ℃ / 90 ℃ heat shrinkage rate

The film is cut into a width of 15 mm and a length of 300 mm with respect to the direction to be measured, and heat-treated for 10 seconds in a constant temperature water bath maintained at a set temperature (70 ° C, 80 ° C, and 90 ° C), and then the length (l) of the film is measured. The thermal shrinkage was calculated by the following equation (2):

(4) longitudinal shrinkage gradient constant

Using the 70 ° C., 80 ° C. and 90 ° C. heat shrinkage measured in item (3) above, the longitudinal shrinkage gradient constant (S) was calculated according to Equation 1 below:

[Equation 1]

S = (S ₈₀ -S ₇₀ ) / (S ₉₀ -S ₈₀ )

Where

S ₇₀ is the shrinkage rate in the longitudinal direction, which is the main shrinkage direction of the film after holding for 10 seconds in 70 ℃ hot water,

S ₈₀ is the shrinkage rate in the longitudinal direction which is the main shrinkage direction of the film after holding for 10 seconds in 80 ℃ hot water,

S ₉₀ is the shrinkage rate in the longitudinal direction, which is the main shrinkage direction of the film, after holding for 10 seconds at 90 ° C. hot water.

(5) haze

Haze was measured using an XL 211 haze meter from Gardner.

From the results of Table 2, the polyester film of Examples 1 and 2 prepared according to the present invention is certainly excellent in the ultraviolet absorbency and the breaking strength in the longitudinal direction in the running direction, compared to the films of Comparative Examples 1 to 3, The heat shrinkage at 70 ° C. in the longitudinal direction is low, while the heat shrinkage at 90 ° C. is high, indicating excellent UV protection, mechanical strength and labeling properties.

Claims (11)

(i) comprising an ethylene terephthalate main repeating unit and an ultraviolet absorber,
(ii) a light transmittance of 10% or less at a wavelength of 360 nm or less and a light transmittance of 60% or more at a wavelength of 400 nm,
(iii) the haze is less than 10,
(iv) The shrinkage in the longitudinal direction, which is the main shrinkage direction of the film, after holding for 10 seconds at 90 ° C. hot water for at least 65%, and the shrinkage in the longitudinal direction, which is the main shrinkage direction of the film, after holding for 10 seconds at 70 ° C. Below, the longitudinal shrinkage gradient constant (S) defined by the following formula (1) is 2.5 to 4, polyester-based heat shrink film:
[Equation 1]
S = (S ₈₀ -S ₇₀ ) / (S ₉₀ -S ₈₀ )
Where
S ₇₀ is the shrinkage rate in the longitudinal direction, which is the main shrinkage direction of the film after holding for 10 seconds in 70 ℃ hot water,
S ₈₀ is the shrinkage rate in the longitudinal direction which is the main shrinkage direction of the film after holding for 10 seconds in 80 ℃ hot water,
S ₉₀ is the shrinkage rate in the longitudinal direction, which is the main shrinkage direction of the film, after holding for 10 seconds at 90 ° C. hot water. The method of claim 1,
The polyester-based heat-shrink film is characterized in that stretched in the total stretching ratio of 3.5 to 4.5 times in the longitudinal direction. The method of claim 1,
The polyester heat-shrink film has a breaking strength in the longitudinal direction of 20 kgf / mm ² or more, and an elongation at break in the longitudinal direction of less than 80%. The method of claim 1,
The ultraviolet absorber is selected from the group consisting of salicylic acid-based, benzotriazole-based, benzophenone-based, cyanoacrylate-based compound and mixtures thereof. The method of claim 1,
The polyester-based heat shrink film is a polyester-based heat shrink film, characterized in that it comprises an ultraviolet absorber in an amount of 0.2 to 0.7% by weight based on the total weight of the film. The method of claim 1,
The polyester-based heat-shrink film has a thickness of 12 to 75 ㎛. (1) melting and extruding a polyester film-forming composition comprising an ethylene terephthalate main repeating unit and an ultraviolet absorber at a temperature of 220 to 285 ° C. to produce a molten sheet;
(2) cooling and solidifying the melt sheet to produce a cooled solidified polyester unstretched sheet; And
(3) drawing the unstretched sheet at a total draw ratio of 3.5 to 4.5 times the longitudinal direction of the sheet;
The manufacturing method of the polyester type heat shrink film in any one of Claims 1-6. The method of claim 7, wherein
A method for producing a polyester-based heat shrink film, characterized in that the unstretched sheet is stretched by a longitudinal stretching method giving a peripheral speed difference between rolls. The method of claim 8,
The stretching is composed of a preheating unit, a stretching unit and a cooling unit, each of which is carried out at a temperature of 65 ~ 80 ℃, 75 ~ 90 ℃ and 50 ~ 25 ℃ polyester manufacturing method of the heat-shrink film. A packaging material comprising the polyester-based heat shrink film according to any one of claims 1 to 6. Label comprising the polyester-based heat shrink film according to any one of claims 1 to 6.