JP4501043B2 - Heat-shrinkable polyester film - Google Patents

Description

【００７１】
表１から明らかなように、実施例１〜４で得られたフィルムはいずれも収縮仕上り性が良好であった。また、圧縮強度も十分で厚み分布も良好であった。本発明の熱収縮性ポリエステル系フィルムは高品質で実用性が高く、特に収縮ラベル用として好適である。
【００７２】
一方、比較例１で得られた熱収縮性フィルムは収縮仕上がり性と厚み分布が劣っていた。また、比較例２および比較例３で得られた熱収縮性フィルムは、圧縮強度が劣っていた。このように比較例で得られた熱収縮性ポリエステル系フィルムはいずれも品質が劣り、実用性が低いものであった。
【００７３】
【発明の効果】
本発明によれば、熱収縮によるシワ、収縮斑、歪み及び収縮不足の発生が極めて少ない良好な仕上がり性が可能であり、また高速装着に耐えるフィルム腰を有し及び短時間で高収縮率となる収縮性能を有する熱収縮フィルムが得られる。
【００７４】
従って、高速でのラベルの装着及び収縮が必要とされているＰＥＴボトルのラベル用の熱収縮性ポリエステル系フィルムとして好適である。
【図面の簡単な説明】
【図１】ＰＥＴボトルに収縮フィルムを装着する状態を示す説明図である。
【図２】ＰＥＴボトルに収縮フィルムを装着して収縮した後の状態を示す要部正面図である。
【符号の説明】
１ ＰＥＴボトル
２ ラベル
３ 加圧部材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat-shrinkable polyester film, and more particularly to a heat-shrinkable polyester film suitable for label applications. More specifically, the present invention relates to a heat-shrinkable polyester film which is for labels and has very little wrinkles, shrinkage spots and distortions due to heat shrinkage and has a high compressive strength.
[0002]
[Prior art]
As a heat-shrinkable film, particularly a heat-shrinkable film for labeling the body of a PET bottle, a film made of polyvinyl chloride, polystyrene or the like is mainly used. However, with regard to polyvinyl chloride, in recent years, there has been a problem of generation of chlorine gas when incinerated at the time of disposal, and polystyrene has problems such as difficulty in printing. Furthermore, in collecting and recycling PET bottles, it is necessary to separate labels of resins other than PET such as polyvinyl chloride and polystyrene. For this reason, polyester-based heat-shrinkable films that do not have these problems are attracting attention.
[0003]
However, many heat-shrinkable polyester films shrink rapidly, leaving wrinkles, shrinkage spots and distortion after shrinkage, and tending to break due to external impact after shrinkage. I was not satisfied.
[0004]
In order to avoid some of these drawbacks, Japanese Patent Publication No. 7-77757 discloses a method for improving the shrinkage finish by significantly reducing the breaking strength in the direction orthogonal to the main shrinkage direction.
[0005]
Japanese Patent Application Laid-Open No. 58-64958 discloses a method for improving shrinkage finish by reducing orientation return stress.
[0006]
However, the film obtained by the above-mentioned method was not satisfactory as a shrink film because a sufficient shrink finish could not be obtained for small PET bottle applications where the shrink tunnel passage time was short. That is, when a cylindrical label formed from a shrink film is attached to a PET bottle and heat-treated to shrink the shrink film, wrinkles, shrinkage spots, and distortion due to shrinkage may occur in the film.
[0007]
Furthermore, beverage filling lines such as PET bottles have been accelerated, and as described above, the label shrinkage finish is good, and naturally high-speed wearing suitability is required. That is, as shown in FIGS. 1 and 2, when the label 2 is mounted on the PET bottle 1 with the pressurizing member 3 at a high speed, if the label is not suitable for high-speed mounting, the label may be folded and cannot be mounted. . Label attachment suitability is largely due to the strength of the film, and increasing the thickness of the film can cope with it, but it also has a negative effect. For example, when the thickness of the film increases, the weight increases and the handleability decreases. In addition, the cost may increase due to an increase in film thickness.
[0008]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems, and the object of the present invention is to achieve high-speed mounting suitability and shrink finish finish without increasing the thickness setting in all applications including small PET bottles. The object is to provide a shrinkable polyester film.
[0009]
[Means for Solving the Problems]
The heat-shrinkable polyester film of the present invention contains 14 mol% or more of isophthalic acid in all acid components, 0.1 to 5 mol% of adipic acid, and 5 to 15 mol% of butanediol in all glycol components. The hot-shrinkage rate of the polyester film is 20% or more at a treatment temperature of 70 ° C. and a treatment time of 5 seconds in the main shrinkage direction. It is 35 to 55% at 75 ° C. and a treatment time of 5 seconds, 50 to 60% at a treatment temperature of 80 ° C. and a treatment time of 5 seconds, and the compression strength of a label formed from the film is expressed by the following formula (1 ), And the above object is achieved.
y> 1.1x ^2.2 (1)
Wherein, y is compressive strength (mN), x is the table the film thickness ([mu] m),
Here, the compressive strength of the label is measured by the following method:
A label having a folding diameter of 175 mm and a length of 120 mm was prepared so that the bottom surface where the label was folded was a square cylinder, and a strograph (model: V10-C) manufactured by Toyo Seiki Co., Ltd. was used. By measuring the maximum compressive strength (mN) at a crosshead speed of 200 mm / min in the compression mode, the compressive strength in the vertical direction of the cylinder is measured.
[0010]
In one embodiment, the thickness distribution is 6% or less.
[0011]
The bottle label of the present invention is produced using the heat-shrinkable polyester film, thereby achieving the object.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below.
[0013]
The heat-shrinkable polyester film of the present invention is produced from a polyester having a dicarboxylic acid component and a diol component as constituent components.
[0014]
Examples of the dicarboxylic acid component constituting the polyester 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, and An alicyclic dicarboxylic acid etc. are mentioned.
[0015]
When an aliphatic dicarboxylic acid (for example, adipic acid, sebacic acid, decanedicarboxylic acid, etc.) is contained, the content is preferably less than 3 mol% (the same applies to all dicarboxylic acid components used). In heat-shrinkable polyester films obtained using polyesters containing 3 mol% or more of these aliphatic dicarboxylic acids, the elongation at break in the direction perpendicular to the main shrinkage direction after shrinkage treatment tends to decrease, and high speed Insufficient film waist when worn.
[0016]
Further, it is preferable not to contain a trivalent or higher polyvalent carboxylic acid (for example, trimellitic acid, pyromellitic acid, and anhydrides thereof). Preferably it is 3 mol% or less. In heat-shrinkable polyester films obtained using polyesters containing these polyvalent carboxylic acids, the degree of judgment in the direction perpendicular to the main shrinkage direction after shrinkage treatment tends to decrease, and the required high shrinkage rate Is difficult to achieve.
[0017]
Examples of the diol component constituting the polyester used in the present invention include aliphatic diols such as ethylene glycol, propanediol, butanediol, neopentylglycol, and hexanediol; alicyclic diols such as 1,4-cyclohexanedimethanol, and aromatics. Group diols and the like.
[0018]
The polyester used for the heat-shrinkable polyester film of the present invention contains at least one of diols having 3 to 6 carbon atoms (for example, propanediol, butanediol, neopentylglycol, hexanediol, etc.), and is made of glass. A polyester having a transition point (Tg) adjusted to 60 to 75 ° C. is preferred.
[0019]
Further, neopentyl glycol can be used as one kind of diol component in order to obtain a heat-shrinkable polyester film with particularly excellent shrink finish. Preferably, it is 15 to 25 mol% (the same applies hereinafter with respect to all diol components used).
[0020]
It is preferable not to contain a diol having 8 or more carbon atoms (for example, octanediol) or a trihydric or higher polyhydric alcohol (for example, trimethylolpropane, trimethylolethane, glycerin, diglycerin, etc.). Preferably it is 3 mol% or less. In the heat-shrinkable polyester film obtained by using polyester containing these diols or polyhydric alcohols, it is difficult to achieve a necessary high shrinkage rate.
[0021]
The polyester preferably contains as little diethylene glycol, triethylene glycol and polyethylene glycol as possible. In particular, diethylene glycol is likely to be present because it is a by-product component during polyester polymerization. However, in the polyester used in the present invention, the content of diethylene glycol is preferably less than 4 mol%.
[0022]
Preferred acid components and diol components used in the polyester of the present invention are as follows. The main acidic content is terephthalic acid, 14% by mole or more of isophthalic acid, and 0.1% by mole or more and less than 5% by mole of adipic acid. Particularly preferred are 14 to 20 mol% isophthalic acid and 1 to 4 mol% adipic acid. The main diol component is ethylene glycol and 5 to 15 mol% of butanediol is blended. Particularly preferred are ethylene glycol 93 to 87 mol% and butanediol 7 to 13 mol%.
[0023]
In addition, the content rate of the said acid component and a diol component is a content rate with respect to the acid component of a whole polyester, and a diol component, when mixing and using 2 or more types of polyester. It does not matter whether transesterification has taken place after mixing.
[0024]
Furthermore, in order to improve the slipperiness of the heat-shrinkable film, for example, an inorganic lubricant such as titanium dioxide, fine-particle silica, kaolin, calcium carbonate, or an organic lubricant such as a long-chain fatty acid ester may be included. preferable. Moreover, you may contain additives, such as a stabilizer, a coloring agent, antioxidant, an antifoamer, an antistatic agent, and an ultraviolet absorber, as needed.
[0025]
Any of the above polyesters can be produced by polymerization according to a conventional method. For example, the polyester can be obtained by using a direct esterification method in which a dicarboxylic acid and a diol are directly reacted, or a transesterification method in which a dicarboxylic acid dimethyl ester is reacted with a diol. The polymerization may be performed by either a batch method or a continuous method.
[0026]
The heat-shrinkable polyester film of the present invention is treated with no load in warm water and the length before and after shrinkage is calculated as follows: thermal shrinkage rate = ((length before shrinkage−length after shrinkage) / before shrinkage The hot water shrinkage rate of the film calculated by the formula of (length) × 100 (%) is 20% or more at a treatment temperature of 70 ° C. and a treatment time of 5 seconds in the main shrinkage direction, preferably 22 to 35%. It is 35 to 55% at 75 ° C for 5 seconds, preferably 40 to 50%, and 50 to 60% at 80 ° C for 5 seconds.
[0027]
When the hot water shrinkage rate in the main shrinkage direction is less than 20% at 70 ° C. for 5 seconds, the low temperature shrinkability is insufficient, and it is necessary to increase the shrinkage temperature. On the other hand, if it exceeds 50%, the label jumps up due to heat shrinkage, which is not preferable.
[0028]
The shrinkage rate at 75 ° C. for 5 seconds is 35 to 55%. When the shrinkage rate is less than 35%, the shrinkage of the mouth of the bottle becomes insufficient (that is, the shrinkage is caused by wrapping a packaging body such as a bottle). When passing through a tunnel, the ends are wide like petals, and shrinkage spots and wrinkles are likely to occur). On the other hand, when it exceeds 55%, there is a force to further shrink even after heat shrinkage, so that the label is likely to jump up.
[0029]
The shrinkage rate at 80 ° C. for 5 seconds is 50 to 60%, and when it is less than 50%, the shrinkage of the mouth of the bottle is not preferable. On the other hand, when it exceeds 60%, there is a force to further shrink even after heat shrinkage, so that the label is likely to jump up.
[0030]
In the heat-shrinkable polyester film of the present invention, the compressive strength of a label produced from the film satisfies the following formula (1).
y> x ^2.2 (1)
In the formula, y represents compressive strength (mN), and x represents film thickness (μm).
[0031]
The preferred label compressive strength y is as follows.
y> 1.1x ^2.2 (1a)
Although the compressive strength is affected by the thickness of the film, if the above formula is not satisfied due to the suitability for a high-speed mounting machine, there is a possibility that a problem of label mounting failure may occur.
[0032]
The thickness x of the heat-shrinkable polyester film of the present invention is not particularly limited, but is preferably 10 to 200 μm, more preferably 20 to 100 μm, as the heat-shrinkable film for labels.
[0033]
Next, although a specific example is demonstrated about the manufacturing method of the heat-shrinkable polyester film of this invention, it is not limited to this manufacturing method.
[0034]
The polyester raw material used in the present invention is dried using a dryer such as a hopper dryer or a paddle dryer, or a vacuum dryer, melted at a temperature of 200 to 300 ° C., and extruded into a film. In extruding, any existing method such as a T-die method or a tubular method may be employed. After extrusion, it is cooled rapidly to obtain an unstretched film.
[0035]
Next, the obtained unstretched film is Tg−5 ° C. or higher of polyester, Tg + 15 ° C. of polyester (for example, 70 ° C. to 90 ° C.), 1.05 times or more in the longitudinal direction (extrusion direction), Preferably, the film is stretched 1.05 to 1.20 times. Next, after preheating the film, it is stretched 4.5 times or more in the transverse direction (main shrinkage direction) (primary stretching). Preferably it is 4.7 to 5.2 times. Here, by preheating the film, shrinkage can be suppressed and the film can be strengthened. Thereafter, the film is further stretched 1.05 times or more in the transverse direction at 65 to 85 ° C. (secondary stretching) to obtain the heat-shrinkable polyester film of the present invention.
[0036]
By stretching in two steps in this way, the film can be strengthened, and high-speed shrinkage and high-speed mounting can be supported.
[0037]
The stretching method is a method of stretching in the transverse direction with a tenter in addition to stretching in the longitudinal direction to perform biaxial stretching. Such biaxial stretching can be performed by either sequential biaxial stretching method or simultaneous biaxial stretching method. This method may be used, and if necessary, restretching may be performed in the longitudinal direction or the transverse direction.
[0038]
In order to achieve the object of the present invention, the lateral direction is practical as the main shrinking direction. Thus, the example of the film forming method in the case where the main shrinking direction is the lateral direction has been described above. Even when the shrinking direction is the longitudinal direction, a film can be formed according to the operation of the above method except that the stretching direction in the above method is changed by 90 degrees.
[0039]
In this invention, it is preferable to extend | stretch the unstretched film obtained from polyester at the temperature of Tg-5 degreeC or more and less than Tg + 15 degreeC.
[0040]
When the film is stretched at a temperature lower than Tg-5 ° C., not only is it difficult to obtain the heat shrinkage rate which is a constituent of the present invention, but the transparency of the obtained film is deteriorated, which is not preferable.
[0041]
Further, when the film is stretched at a temperature of Tg + 15 ° C. or more, the obtained film is not preferable because the film stiffness at the time of high-speed mounting is insufficient and the uneven thickness of the film is remarkably impaired.
[0042]
The heat-shrinkable polyester film of the present invention has a film thickness distribution of 6% or less calculated from the thickness of the film according to the formula: thickness distribution = ((maximum thickness−minimum thickness) / average thickness) × 100 (%). It is preferable that More preferably, it is 5% or less.
[0043]
A film having a thickness distribution of 6% or less is easy to superimpose colors by, for example, three-color printing performed at the time of shrinkage finish evaluation, whereas a film exceeding 6% is preferable in terms of color superposition. Absent.
[0044]
In order to make the thickness distribution of the heat-shrinkable polyester film uniform, when the film is stretched in the transverse direction using a tenter, the heat transfer coefficient is 0.0013 calories / min in the preheating process performed prior to the stretching process. Heating is preferably performed until the film temperature reaches a predetermined film temperature at a low wind speed so as to be equal to or less than cm ² · sec · ° C.
[0045]
Further, in order to suppress the internal heat generation of the film accompanying stretching and reduce the film temperature unevenness in the width direction, the heat transfer coefficient in the stretching process is 0.0009 calories / cm ² · sec · ° C. or more, preferably 0.00. A condition of 0011 to 0.0017 calories / cm ² · sec · ° C. is preferable.
[0046]
When the heat transfer coefficient in the preheating process exceeds 0.0013 calories / cm ² · sec, and when the heat transfer coefficient in the drawing process is less than 0.0009 calories / cm ² · sec, the thickness distribution becomes uniform. When the obtained film is subjected to multi-color printing, it is not preferable that a pattern shift occurs due to multi-color superposition.
[0047]
The label of the present invention is produced by rounding a rectangular heat-shrinkable film having a predetermined size into a cylindrical shape, bonding ends to form a tubular body, and further cutting the tubular body. Although it does not limit as an adhesion | attachment method, For example, a solvent or a swelling agent is apply | coated to at least one side of the joining surface of a polyester-type film, and it joins before drying.
[0048]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples, unless the summary is exceeded.
[0049]
The evaluation method of the film of the present invention is as follows.
[0050]
(1) The heat shrinkage rate film is cut into a 10 cm × 10 cm square, heat-shrinked in warm water at a predetermined temperature ± 0.5 ° C. for a predetermined time in a no-load state, and then the longitudinal and horizontal directions of the film. Were measured, and the thermal shrinkage rate was determined according to the following formula (2). The direction in which the heat shrinkage rate is large was taken as the main shrinkage direction.
[0051]
Thermal shrinkage rate = ((length before shrinkage−length after shrinkage) / length before shrinkage) × 100 (%) (2)
[0052]
(2) Three-color printing was performed in advance on a heat-shrinkable film having a shrink finish, using grass, gold, and white ink from Toyo Ink Manufacturing Co., Ltd.
[0053]
Using a steam tunnel (model: SH-1500-L) manufactured by Fuji Astec Inc., passing time 2.5 seconds, zone temperature 80 ° C., 500 ml round bottle (height 20.6 cm, central diameter 6.5 cm: ( A bottle manufactured by Yoshino Kogyo Co., Ltd. and used in the afternoon tea of Kirin Beverage Co., Ltd.) (number of measurements = 20).
[0054]
Evaluation was made visually and the criteria were as follows.
[0055]
No wrinkles, jumping up, or insufficient shrinkage occurred: ○
Wrinkles, jumping up, or insufficient shrinkage occurred: ×
[0056]
(3) Compressive strength A label having a folding diameter of 175 mm and a length of 120 mm was prepared, and the bottom surface of the folded label was formed into a rectangular cylinder, and the vertical compressive strength of the cylinder was measured. The maximum value of compressive strength (mN) at a crosshead speed of 200 mm / min was measured in a compression mode using a strograph (model: V10-C) manufactured by Toyo Seiki Co., Ltd. (number of samples = 5).
[0057]
(4) Tg (glass transition point)
Using DSC (model: DSC220) manufactured by Seiko Denshi Kogyo Co., Ltd., 10 mg of an unstretched film was heated from −40 ° C. to 120 ° C. at a heating rate of 20 ° C./min. From the obtained endothermic curve Asked. A tangent line was drawn before and after the inflection point of the endothermic curve, and the intersection was defined as Tg (glass transition point).
[0058]
(5) Thickness distribution Using a contact thickness meter (model: KG60 / A) manufactured by Anritsu Co., Ltd., the thickness of the sample of 5 cm in the vertical direction and 50 cm in the horizontal direction was measured (measurement number = 20). The thickness distribution (thickness variation) was determined by the following equation (3). Moreover, the average value (n = 50) of the thickness distribution was evaluated according to the following criteria.
[0059]
Thickness distribution = ((maximum thickness−minimum thickness) / average thickness) × 100 (%) (3)
6% or less → ○
More than 6% and less than 10% → △
10% or more → ×
The polyester used in the examples is as follows.
[0060]
Polyester A: Polyethylene terephthalate (Intrinsic viscosity (IV) 0.75 dl / g)
Polyester B: Polyester composed of 78 mol% terephthalic acid, 22 mol% isophthalic acid and ethylene glycol (IV 0.72 dl / g)
Polyester C: Polyester (IV 0.77 dl / g) composed of 65 mol% terephthalic acid, 10 mol% isophthalic acid, 25 mol% adipic acid and butanediol
Polyester D: Polyester (IV 0.72 dl / g) composed of terephthalic acid, ethylene glycol 70 mol%, neopentyl glycol 30 mol%
Polyester E: Polybutylene terephthalate (IV 1.20 dl / g)
[0061]
Example 1
A polyester in which 20% by weight of polyester A, 70% by weight of polyester B and 10% by weight of polyester C were mixed was melted at 280 ° C., extruded from a T-die, and quenched with a chill roll to obtain an unstretched film.
[0062]
The unstretched film was stretched 1.1 times in the machine direction at 80 ° C., and then preheated until the film temperature reached 88 ° C. under the condition of a thermal conductivity coefficient of 0.033 W / (m · ° C.) The film was stretched 4.6 times in the transverse direction at 70 ° C. (primary stretching). Subsequently, it heat-processed for 10 second at 70 degreeC, and also it extended | stretched 1.1 times at 68 degreeC to the horizontal direction (secondary extending | stretching), and obtained the 50-micrometer-thick heat-shrinkable polyester film.
[0063]
(Example 2)
A heat-shrinkable polyester film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that polyester mixed with 6% by weight of polyester A, 84% by weight of polyester B, and 10% by weight of polyester C was used.
[0064]
(Example 3)
A heat-shrinkable polyester film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the film was stretched 5.5 times (primary stretching) at 72 ° C. in the width direction.
[0065]
Example 4
A heat-shrinkable polyester film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the film was stretched 1.5 times in the longitudinal direction (primary stretching).
[0066]
(Comparative Example 1)
A heat-shrinkable polyester film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the primary stretching temperature was 80 ° C.
[0067]
(Comparative Example 2)
A heat-shrinkable polyester film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the film was stretched 1 time in the longitudinal direction and 4 times (primary stretching) in the width direction.
[0068]
(Comparative Example 3)
A heat-shrinkable polyester system having a thickness of 50 μm was used in the same manner as in Comparative Example 2 except that a polyester in which 25% by weight of polyester A, 50% by weight of polyester D and 25% by weight of polyester E were mixed and stretched in the transverse direction at 74 ° C. A film was obtained.
[0069]
Table 1 shows the evaluation results of the films obtained in Examples 1 to 4 and Comparative Examples 1 to 3.
[0070]
[Table 1]

[0071]
As is clear from Table 1, the films obtained in Examples 1 to 4 all had good shrinkage finish. Moreover, the compressive strength was sufficient and the thickness distribution was good. The heat-shrinkable polyester film of the present invention has high quality and high practicality, and is particularly suitable for shrinkage labels.
[0072]
On the other hand, the heat shrinkable film obtained in Comparative Example 1 was inferior in shrink finish and thickness distribution. Moreover, the heat-shrinkable film obtained in Comparative Example 2 and Comparative Example 3 was inferior in compressive strength. Thus, all the heat-shrinkable polyester films obtained in the comparative examples were inferior in quality and low in practicality.
[0073]
【The invention's effect】
According to the present invention, it is possible to achieve a good finish with very little occurrence of wrinkles, shrinkage spots, distortion and insufficient shrinkage due to heat shrinkage, a film waist that can withstand high-speed mounting, and a high shrinkage rate in a short time. A heat-shrinkable film having the shrinkage performance is obtained.
[0074]
Therefore, it is suitable as a heat-shrinkable polyester film for labels of PET bottles that require label mounting and shrinkage at high speed.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a state in which a shrink film is attached to a PET bottle.
FIG. 2 is a main part front view showing a state after a shrink film is attached to a PET bottle and contracted.
[Explanation of symbols]
1 PET bottle 2 Label 3 Pressure member

Claims (3)

Heat shrinkability characterized by comprising 14 mol% or more of isophthalic acid in all acid components, 0.1 mol% or more and less than 5 mol% of adipic acid, and 5 to 15 mol% of butanediol in all glycol components. The polyester film has a hot water shrinkage ratio of 20% or more at a treatment temperature of 70 ° C. and a treatment time of 5 seconds in the main shrinkage direction, and is 35 to 35% at a treatment temperature of 75 ° C. and a treatment time of 5 seconds. The heat is 55%, the processing temperature is 80 ° C., the processing time is 50 to 60% at 5 seconds, and the compression strength of the label formed from the film satisfies the following formula (1): Shrinkable polyester film:
y> 1.1x ^2.2 (1)
Wherein, y is compressive strength (mN), x is the table the film thickness ([mu] m),
Here, the compressive strength of the label is measured by the following method:
A label having a folding diameter of 175 mm and a length of 120 mm was prepared so that the bottom surface where the label was folded was a square cylinder, and a strograph (model: V10-C) manufactured by Toyo Seiki Co., Ltd. was used. By measuring the maximum compressive strength (mN) at a crosshead speed of 200 mm / min in the compression mode, the compressive strength in the vertical direction of the cylinder is measured.   The heat-shrinkable polyester film according to claim 1, wherein the thickness distribution is 6% or less.   The label for bottles produced using the heat-shrinkable polyester-type film of Claim 1 or 2.

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