JP2001205704A - Heat shrinkable polyester-based film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat shrinkable polyester film suitable for a label application which has an excellent shrinking property in a wide temperature range from a low temperature to a high temperature, particularly in the low temperature range, generates very little amount of shrinkage spot, wrinkle, distortion and longitudinal sink mark and shows excellent breakage resistance. SOLUTION: A heat shrinkable polyester has a tan δ value of dynamic visco- elasticity of not less than 0.05 in the direction of major shrinkage at 60 deg.C, a temperature at a maximum tan δof 65 to 80 deg.C and the peak value of the tan δ of not less than 0.40, heat shrinkage of not less than 30% after a treatment in hot water at 80 deg.C for 10 seconds and an initial breakage of 0% in the direction of major shrinkage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-shrinkable polyester film.
The present invention relates to a heat-shrinkable polyester film excellent in wrinkles, distortion, vertical shrinkage and the like, and excellent in tear resistance and suitable for label use.

[0002]

2. Description of the Related Art Conventionally, heat shrinkable films have been widely used for applications such as shrink wrapping, shrink labels, and cap seals, utilizing the property of shrinking by heating. Above all,
A heat-shrinkable stretched film made of a vinyl chloride resin, a polystyrene resin, a polyester resin, or the like is used for a polyethylene terephthalate (PET) container, a polyethylene container,
It is used for labels on various containers such as glass containers.

However, vinyl chloride resins have problems such as low heat resistance and generation of hydrogen chloride gas during incineration. When a heat-shrinkable vinyl chloride resin film is used as a shrinkable label for a PET container or the like, it is necessary to separate the label from the container when recycling the container.

On the other hand, polystyrene resin and polyester resin films do not generate harmful substances such as hydrogen chloride gas during incineration, and are expected to be used as shrink labels for containers instead of vinyl chloride resin films.

However, polystyrene resin films are
Although the finished appearance after shrinkage is good, special ink must be used for printing due to poor solvent resistance. In addition, it requires incineration at a high temperature and generates a large amount of black smoke and an unpleasant odor at the time of incineration.

[0006]

As a material capable of solving the above-mentioned problems, polyester resin films are highly expected, and the amount of use thereof is increasing. However, the conventional heat-shrinkable polyester films described above have not been sufficiently satisfactory in their heat-shrink properties. In particular, shrinkage spots and wrinkles are likely to occur during heat shrinkage.
When covering the body of containers such as bottles, polyethylene bottles, glass bottles, etc., characters and designs printed on the film before shrinkage may be distorted after shrinkage, or the film may not be tightly adhered to the container, etc. Had a problem. Furthermore, compared to the heat-shrinkable polystyrene-based film, the shrinkage at low temperatures is inferior, and in order to obtain the required amount of shrinkage, the film must be shrunk at a higher temperature, causing deformation and whitening of bottles and the like. He had problems.

When shrinking the coating on an industrial production scale, a heat-shrinkable film processed into a form such as a label, a tube or a bag is attached to a container, and then steam-blowed to heat shrink. In general, a shrinking tunnel (steam tunnel) or a shrinking tunnel (hot air tunnel) of a type in which hot air is blown to thermally shrink is placed on a belt conveyor or the like to pass through and shrink the coating. Since the steam tunnel has a higher heat transfer efficiency than the hot air tunnel, it can be heated and shrunk more uniformly, and a better shrink finish can be obtained as compared with the hot air tunnel. However, the conventional mature shrinkable polyester film is inferior to the heat shrinkable vinyl chloride resin film or the heat shrinkable polystyrene resin film in terms of shrink finish. In a hot air tunnel, temperature unevenness is likely to occur during thermal contraction, and as a result, shrinkage unevenness, wrinkles, distortion, and the like are particularly likely to occur. For this reason, the conventional heat-shrinkable polyester film is inferior to the heat-shrinkable vinyl chloride resin or the heat-shrinkable polystyrene film in the shrink finish in the hot air tunnel.

The present invention has excellent shrinkage characteristics in a wide temperature range from a low temperature to a high temperature, particularly in a low temperature range, and has very little occurrence of shrinkage spots, wrinkles, distortions, and vertical shrinkage, and also has excellent tear resistance. It is an object of the present invention to provide a heat-shrinkable polyester film suitable for label use.

[0009]

In order to achieve the above object, the heat-shrinkable polyester film of the present invention is made of polyester and has a tan δ value of dynamic viscoelasticity at 60 ° C. in the main shrinkage direction of 0.05 or more. , The temperature at which the tan δ value becomes the maximum is 65 to 80 ° C., the tan δ maximum value is 0.40 or more, and the heat shrinkage in the main shrinkage direction after the treatment in 80 ° C. hot water for 10 seconds is 30% or more. Wherein the initial rupture rate in the direction perpendicular to the main shrinkage direction is 0%.

[0010] Here, the initial breaking ratio is defined as JIS-C-2.
The elongation at break is measured in the direction perpendicular to the main shrinkage direction according to 318 (the number of samples n = 20), and the number (x) of the samples having elongation at break of 5% or less is determined, which means a value calculated by the following equation. . Initial breaking rate = (x / n) × 100 (%)

The heat-shrinkable polyester film having the above properties has excellent shrink finish in a wide temperature range from a low temperature to a high temperature, particularly in a low temperature range.
A beautiful shrink-finished appearance with very few wrinkles and distortions can be obtained, and excellent tear resistance.

In this case, the heat shrinkage in the direction orthogonal to the main shrinkage direction after the film is treated in hot water at 80 ° C. for 10 seconds is preferably 10% or less.

The heat-shrinkable polyester film having the above characteristics has excellent shrink finish in a wide temperature range from a low temperature to a high temperature, and can obtain a beautiful shrink finish appearance with less flaking.

In this case, the polyester is preferably a polyester containing at least one dimer acid component and / or dimer diol component.

The heat-shrinkable polyester film having the above constitution has excellent shrink finish in a wide temperature range from a low temperature to a high temperature, and is particularly excellent in shrink finish in a low temperature range. Excellent tear resistance.

[0016]

Embodiments of the present invention will be described below. The heat-shrinkable polyester film of the present invention needs to have a tan δ value at 60 ° C. in the main shrinkage direction of 0.05 or more, measured by a dynamic viscoelasticity measuring device. After attaching the heat-shrinkable film to a container such as a label or tube, heat shrink in a shrink tunnel.In the process of industrial production, the surface on the side where the heat-shrinkable film and the container are in contact. The temperature varies depending on the process and the container used, but is generally as low as 85 ° C. or less. Dynamic viscoelastic tan in the main shrinkage direction at low temperature
The δ value is a factor that affects the occurrence of shrinkage spots, wrinkles, distortions, and the like during shrinkage.
If the value is 0.05 or more at 60 ° C., in a process of industrial production in which heat shrinks in a shrink tunnel, shrinkage spots, wrinkles,
The occurrence of defects such as distortion is extremely reduced. The tan δ value of the dynamic viscoelasticity in the main shrinkage direction is more preferably 0.15 or more at 60 ° C.

Further, in the present invention, the temperature at which the tan δ value of the dynamic viscoelasticity in the main shrinkage direction becomes maximum is 65 ° C.
８０80 ° C. is required. If the temperature at which the tan δ value of the dynamic viscoelasticity in the main shrinkage direction becomes the maximum is less than 65 ° C., the tear resistance at room temperature is deteriorated, and the physical properties of the film with the passage of time tend to change. For example, when stored at room temperature for a long time, the shrinkage at a low temperature of 70 ° C. or less decreases,
A problem occurs in that the shrinkage finish is deteriorated. Further, t
When the temperature at which the an δ value becomes the maximum exceeds 80 ° C., the shrinkage finish in a low temperature range, which is a feature of the present invention, becomes poor.

Further, in the present invention, the maximum value of tan δ in the main shrinkage direction needs to be 0.4 or more.
If the tan δ maximum value is less than 0.4, the crystallinity of the polyester constituting the heat-shrinkable polyester-based film becomes too high, so that a whitening phenomenon due to partial crystallization during heat shrinkage occurs or tubing processing is performed. In this case, the adhesiveness between films using an organic solvent such as tetrahydrofuran, which is usually performed, is deteriorated or impossible. In order to obtain more stable shrink finish appearance and adhesion with an organic solvent, the maximum value of tan δ in the main shrink direction is preferably 0.6 or more.

Further, in the present invention, 8
It is necessary that the heat shrinkage after treatment for 10 seconds in hot water of 0 ° C. is 30% or more. Heat shrinkage rate in hot water of 80 ° C is 3
If it is less than 0%, the shrinkage finish becomes poor due to insufficient shrinkage. In order to obtain a more stable shrink finish appearance, it is preferable that the heat shrinkage after the treatment in hot water of 80 ° C. for 10 seconds in the main shrinkage direction is 40% or more.

In the present invention, the initial rupture rate in the direction orthogonal to the main shrinkage direction must be 0%. If the initial rupture ratio exceeds 0%, the tear resistance of the film becomes poor. In a heat-shrinkable polyester film, molecules are oriented in the main shrinkage direction, so if the tear resistance is poor, it tends to tear along the orientation direction of the molecules, and tension in processing steps such as printing and tuping processing. As a result, there is a problem that the film is broken and the operability of processing is reduced.

Further, in the present invention, the heat shrinkage in the direction orthogonal to the main shrinkage direction after the treatment in hot water at 80 ° C. for 10 seconds is preferably 10% or less. If the heat shrinkage in the direction perpendicular to the main shrinkage exceeds 10%, shrinkage in the direction perpendicular to the main shrinkage causes poor shrink finish (vertical shrinkage). In order to obtain a more stable shrinkage finish, it is preferable that the heat shrinkage after treatment in hot water at 80 ° C. for 10 seconds in a direction orthogonal to the main shrinkage direction is 7% or less.

The thickness of the heat-shrinkable polyester film of the present invention is not particularly limited. For example, the shrinkable film for a label is preferably 10 to 200 μm, more preferably 20 to 100 μm.

The polyester forming the heat-shrinkable polyester film of the present invention comprises, as main components, a dicarboxylic acid component containing an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid or an ester-forming derivative thereof and a polyhydric alcohol component. is there. Examples of the dicarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene-1,4- or -2,6-dicarboxylic acid, and 5-sodium sulfoisophthalic acid. In addition, examples of these ester derivatives include derivatives such as dialkyl esters and diaryl esters. As the aliphatic dicarboxylic acid, dimer acid,
Glutaric acid, adipic acid, sebacic acid, azelaic acid,
Oxalic acid, succinic acid and the like can be mentioned. Further, an oxycarboxylic acid such as p-oxybenzoic acid and a polyvalent carboxylic acid such as trimellitic anhydride and pyromellitic anhydride may be used in combination, if necessary. Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, dimer diol, propylene glycol, triethylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, and 1,6-hexanediol. 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol,
Examples include alkylene glycols such as 1,9-nonanediol and 1,10-decanediol, ethylene oxide adducts of bisphenol compounds or derivatives thereof, trimethylolpropane, glycerin, pentaerythritol, polyoxytetramethylene glycol, polyethylene glycol and the like. . In addition, epsilon caprolactone can be used in place of the polyhydric alcohol.

The polyester forming the heat-shrinkable polyester film of the present invention comprises the above-mentioned dicarboxylic acid component,
Among the polyhydric alcohol components, polyesters containing at least one dimer acid as a dicarboxylic acid component and at least one dimer diol as a polyhydric alcohol component are preferable. By containing dimer acid and / or dimer diol as a component of the polyester forming the heat-shrinkable polyester film of the present invention,
60 ° C in the main shrinkage direction while maintaining the tear resistance of the film
Can increase the tan δ value of the dynamic viscoelasticity in the above, so that the film characteristics can be easily controlled. The dimer acid and the dimer diol are a mixture containing a component having a structure represented by the following formulas (1) and (2) as a main component, and a preferable composition ratio is (1) :( 2) = 10: 90 to 9
0:10. The dimer acid and the timer diol are preferably washed and refined with water.

[0025]

Embedded image

In the present invention, the tan δ value of the dynamic viscoelasticity at 60 ° C., the temperature at which the tan δ value is maximized, and the ta
The maximum value of nδ can be controlled within the target range of the present invention by using the above-mentioned polyester component and the like and the film forming conditions in combination. Such a polyester may be a single polymer,
Two or more polyesters may be used as a mixture. When two or more polyesters are used in combination, a mixed system of polyethylene terephthalate and a copolymerized polyester may be used, or a combination of copolymerized polyesters may be used. Further, a combination with a homopolyester such as polybutylene terephthalate or polycyclohexylene dimethyl terephthalate may be used. A method of mixing two or more polyesters having different secondary transition points (Tg) can also be an effective means for achieving the object of the present invention. As a specific configuration, for example, a polyester in which the dicarboxylic acid component is composed of terephthalic acid and isophthalic acid, and the diol component is ethylene glycol, dimer diol, and polyester having a molecular weight of 500 to 3000, and a single polyester is used. There is a method of using a copolymer system or a mixture of two or more types. These polyesters can be produced by melt polycondensation according to a conventional method, but are not limited thereto, and may be polyesters obtained by other polymerization methods. The degree of polymerization of the polyester is not particularly limited, but is preferably 0.3 to 1.3 dL / g in terms of intrinsic viscosity.

The polyester used in the present invention includes:
In order to improve the heat resistance while keeping the values such as the degree of coloring and the degree of gel generation low, in addition to polycondensation catalysts such as antimony oxide, germanium oxide and titanium compounds, magnesium salts such as magnesium acetate and magnesium chloride, and acetic acid Calcium, Ca salt such as calcium chloride, Mn salt such as manganese acetate and manganese chloride, Zn such as zinc chloride and zinc acetate
A salt, a cobalt salt such as cobalt chloride, cobalt acetate or the like is produced. Each of the polyesters is 300 ppm or less as a metal ion with respect to the polyester, and a phosphoric acid or a phosphate derivative such as trimethyl phosphate or triethyl phosphate is 200 ppm or less in terms of phosphorus (P). It is also possible to add.

The total amount of metal ions other than the above polycondensation catalyst is 300 ppm based on the produced polyester, and phosphorus (P)
If the amount exceeds 200 ppm, not only the coloring of the polymer becomes remarkable, but also the heat resistance and the hydrolysis resistance of the polymer are significantly reduced.

At this time, in terms of heat resistance and hydrolysis resistance, the molar atomic ratio (P / M) of the total P amount (P) to the total metal ion amount (M) is 0.4 to 1. It is preferably 0. When the molar atomic ratio (P / M) is less than 0.4 or more than 1.0, coloring of the composition of the present invention and generation of coarse particles become remarkable, which is not preferable.

The method for producing the polyester used in the present invention is not particularly limited, but a so-called direct polymerization method in which an oligomer obtained by directly reacting a dicarboxylic acid and a glycol is subjected to a so-called direct polymerization method. A so-called transesterification method in which a glycol is transesterified and then polycondensed, and the like, may be used, and any production method can be applied.

The timing of adding the metal ions and phosphoric acid and derivatives thereof is not particularly limited. Generally, the metal ions are charged at the time of charging the raw materials, that is, before transesterification or esterification, and the phosphoric acids are added before the polycondensation reaction. Is preferably added.

Further, if necessary, fine particles such as silica, titanium dioxide, kaolin, and calcium carbonate may be added to the polyester forming the film of the present invention. Further, an antioxidant, an ultraviolet absorber, an antistatic agent, Colorant,
An antibacterial agent or the like can be added. In addition, the preferable intrinsic viscosity of the polyester for forming the film is not limited, but is usually 0.50 to 1.30 dL / g.

Next, a typical method for producing the heat-shrinkable polyester film of the present invention will be described. The polyester raw material used in the present invention is dried using a drier such as a hopper drier, a paddle drier or a vacuum drier.
It is melt extruded into a film at a temperature of 300 ° C. Alternatively, the undried polyester raw material is similarly melt-extruded into a film while removing moisture in a vented extruder. For the extrusion, any existing method such as a T-die method and a tubular method can be adopted. After being extruded and rapidly cooled to obtain an unstretched film, the unstretched film is subjected to a stretching treatment. In order to achieve the object of the present invention, since the transverse direction is practical as the main shrinkage direction, the following main shrinkage direction is used. Shows an example of a film forming method in the case where is a horizontal direction. However, in the case where the main shrinkage direction is the vertical direction, the film can be formed in the same manner as in the ordinary operation except that the stretching direction is changed by 90 degrees in the following method.

As the stretching method, when the main shrinkage direction is the transverse direction, not only the transverse uniaxial stretching with a tenter but also 1.0 to 2.2 times or less, preferably 1.times. 1 to 1.8 times, particularly preferably 1.1 to 1.4 times.
Double stretching can be performed. Stretching in the machine direction can improve the tear resistance of the heat shrinkable film. However, when the film is stretched more than 2.2 times in the machine direction, the heat shrinkage after the treatment in hot water at 80 ° C. for 10 seconds in the direction orthogonal to the main shrinkage direction tends to exceed 10%. It is not preferable as a condition.

Focusing on uniforming the thickness distribution of the desired heat-shrinkable polyester film, when the film is stretched in the transverse direction using a tenter, the heat conduction coefficient is reduced in the preheating process performed prior to the stretching process. At a low wind speed of 0.0013 calories / cm ² · sec · ° C or less
Heating is preferably performed until the film temperature reaches up to Tg + 60 ° C. The stretching in the horizontal direction subsequent to the preheating is carried out at a preheating temperature of -20 ° C to a preheating temperature of -30 ° C by 1.8 to 2.3 times. By such preheating and subsequent first-stage stretching in the transverse direction, the value of tan δ of dynamic viscoelasticity at 60 ° C. in the main shrinkage direction can be increased.

Further, following the above-mentioned first-stage transverse stretching, the first-stage transverse stretching temperature is in the range of +3 to + 5 ° C.
10% and then the first-stage transverse stretching temperature +5 to +1
The film is stretched in a temperature range of 0 ° C. to a total transverse stretching ratio of 3.8 to 4.2 times. By doing so, the shrinkage stress can be reduced, and the longitudinal heat shrinkage can be reduced. Further, the film is stretched 3 to 8% in the transverse direction in the temperature range of the first-stage transverse stretching temperature of -0 to -5 ° C. By doing this,
A heat-shrinkable polyester film having a high heat shrinkage in the transverse direction can be obtained.

In the biaxial stretching in the case where the main contraction direction is set to the horizontal direction and also to the vertical direction, the biaxial stretching is performed sequentially.
Any of simultaneous biaxial stretching may be performed, and re-stretching may be performed if necessary. Further, in the sequential biaxial stretching, any method such as vertical and horizontal, horizontal and vertical, vertical and horizontal, horizontal and vertical and horizontal may be used as the order of stretching. Focusing on suppressing the internal heat generation of the film due to stretching and reducing the film temperature unevenness in the inward direction, the heat transfer coefficient of the stretching process is 0.0009 calories / c.
m ² · sec · ° C. or more, preferably 0.0013 to 0.
The condition of 0020 calories / cm ² · sec · ° C is good.
As described above, the present invention is achieved by a combination of a polyester composition of a film raw material and a stretching method.

[0038]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The method for measuring the physical properties of the film in this specification is shown below.

(1) Dynamic Viscoelasticity Using a dynamic viscoelasticity measuring device manufactured by IT Measurement Co., Ltd., the measurement was performed under the conditions of a measurement length of 3 cm, a displacement of 0.25%, and a frequency of 10 Hz. 60.0 ~
The tan δ value in the range of 60.4 ° C.
It was quantified as an δ value. The sample size was 4 cm in the main contraction direction and 5 mm in the direction perpendicular to the main contraction direction, and the average value of the values at two locations was used.

(2) Heat shrinkage ratio The film is stretched 10 cm × 10 c in the direction perpendicular to the stretching direction.
m, cut in hot water at a predetermined temperature of ± 0.5 ° C. under no load for 10 seconds, and heat-shrinks. Then, the length and width dimensions of the film are measured, and the following formula (1) is obtained. The heat shrinkage was determined according to the following. Heat shrinkage: (length before shrinkage-length after shrinkage) ÷ length before shrinkage x 100 (%) ... (1)

(3) Main shrinkage direction The film is stretched 10 cm × 10 c in the direction perpendicular to the stretching direction.
m, cut into warm water of 80 ° C. ± 0.5 ° C. under no load for 10 seconds, and heat shrink, then measure the length and width dimensions of the film, and have a large heat shrinkage. The direction was defined as the main contraction direction.

(4) Shrinkage finish: 130 ° C. (wind speed 10 m /
Seconds) with hot air of 10 seconds and a glass bottle (300m
L), a heat-shrinkable film label printed in three colors with grass-colored, gold, and white inks was attached, passed through, and visually evaluated for shrinkage finish. The rank of shrinkage finish was evaluated on a 5-point scale. 5: Best finish 4: Good finish 3: Slight shrinkage (within 2 places) 2: Shrinkage unevenness (3 to 5 places) 1: Shrinkage There were many spots (6 or more places), and 4 or more were considered acceptable.

(5) Initial rupture rate The rupture elongation was measured in the direction perpendicular to the main shrinkage direction according to JIS-C-2318 (number of samples n = 20), and the number of samples having a rupture elongation of 5% or less (x ) Was calculated and calculated by the following equation (2). Initial breaking ratio = (x / n) × 100 (%) (2)

Example 1 In a stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux condenser, dimethyl terephthalate 8 was added as a dicarboxylic acid component.
The composition of 0 mol%, 20 mol% of dimethyl isophthalate, 96 mol% of ethylene glycol as a polyhydric alcohol component and 3 mol% of dimer diol is such that the polyhydric alcohol component is 2.2 times the dicarboxylic acid component in molar ratio. And transesterification was carried out using 0.05 mol (based on the acid component) of zinc acetate as a transesterification catalyst while distilling off the generated methanol out of the system. Thereafter, 1 mol% of polytetramethylene glycol (molecular weight: 650)
0.025 mol% of antimony trioxide (based on the acid component) was added as a polycondensation catalyst (based on the acid component), and polycondensation was performed. As a result, a copolymer polyester comprising 80 mol% of a terephthalic acid component, 20 mol% of an isophthalic acid component, 96 mol% of an ethylene glycol component, 3 mol% of a dimer diol component, and 1 mol% of a polytetramethylene glycol (molecular weight 650) component was obtained. . This copolymerized polyester had an intrinsic viscosity of 0.71 dL / g. This polyester was melt-extruded at 280 ° C. and then quenched to obtain an unstretched film having a thickness of 180 μm. The unstretched film was stretched 1.15 times in the machine direction at a stretching temperature of 80 ° C. Then 103
After preheating at 8 ° C. for 8 seconds, the first stretching in the transverse direction was continued for 75 seconds.
At 2.0 ° C., 6% at 78 ° C. in the relaxation step,
Subsequently, the film was stretched in the transverse direction at 80 ° C. such that the total transverse stretching ratio became 4.0 times. Then 5% laterally at 73 ° C
Heat treatment was performed for 6 seconds while elongating to obtain a heat-shrinkable polyester film having a thickness of 43 μm. Table 1 shows the physical property values of the obtained film.

(Example 2) By the same polymerization method as in Example 1, terephthalic acid component 79 mol%, isophthalic acid component 15 mol%, dimer acid component 6 mol%, ethylene glycol component 88 mol%, neopentyl glycol component 10
Mol%, polytetramethylene glycol (molecular weight 65
0) A copolymerized polyester comprising 2 mol% of the component was obtained.
This copolymerized polyester had an intrinsic viscosity of 0.72 dL / g. This polyester was melt-extruded at 280 ° C. and rapidly cooled to obtain a 190 μm-thick unstretched film. The unstretched film is stretched 1.20 in the machine direction at a stretching temperature of 78 ° C.
It was stretched twice. Subsequently, after preheating at 105 ° C. for 8 seconds, the first-stage stretching in the transverse direction was successively relaxed 1.8 times at 75 ° C., relaxed 5% at 76 ° C. in the relaxation step, and subsequently, the total stretching ratio at 80 ° C. was 4%. The film was stretched in the transverse direction so as to be 1 times. Then, heat treatment was performed for 6 seconds at 73 ° C. while elongating 5% in the horizontal direction to obtain a heat-shrinkable polyester film having a thickness of 44 μm. Table 1 shows the physical property values of the obtained film.

Comparative Example 1 By the same polymerization method as in Example 1, 97 mol% of terephthalic acid component, 3 mol% of isophthalic acid component, 71.5 mol% of ethylene glycol component, 28 mol% of neopentyl glycol component, and A copolymerized polyester comprising 0.5 mol% of a tetramethylene glycol (molecular weight: 650) component was obtained. This copolymerized polyester had an intrinsic viscosity of 0.70 dL / g. This polyester is melt-extruded at 280 ° C. and rapidly cooled to a thickness of 195 μm.
m of unstretched film was obtained. The unstretched film is
After preheating at 9 ° C for 9 seconds, stretched 4.3 times at 83 ° C in the transverse direction,
Next, heat treatment was performed at 75 ° C. for 10 seconds to obtain a heat-shrinkable polyester film having a thickness of 45 μm. Table 1 shows the physical property values of the obtained film.

Comparative Example 2 By the same polymerization method as in Example 1, 92 mol% of terephthalic acid component, 8 mol% of isophthalic acid component and 77 mol% of ethylene glycol component, 1,4
-A copolymerized polyester comprising 23 mol% of a butanediol component was obtained. This copolymerized polyester has an intrinsic viscosity of 0.1.
It was 70 dL / g. This polyester was melt-extruded at 280 ° C. and then quenched to obtain an unstretched film having a thickness of 180 μm. After preheating the unstretched film at 95 ° C. for 8 seconds,
The film is stretched 2.3 times at 80 ° C. in the horizontal direction and 1.7 times at 85 ° C., and then heat-treated at 85 ° C. for 15 seconds to obtain a thickness of 44 μm.
m of a heat-shrinkable polyester film was obtained. Table 1 shows the physical property values of the obtained film.

Comparative Example 3 By the same polymerization method as in Example 1, 62 mol% of terephthalic acid component, 38 mol% of isophthalic acid component, 78 mol% of ethylene glycol component, 21 mol% of butanediol component, polytetramethylene glycol (Molecular weight: 650) A copolymerized polyester comprising 1 mol% of the component was obtained. This copolymerized polyester had an intrinsic viscosity of 0.70 dL / g. 280 of this polyester
After being melt-extruded at ℃, the mixture was rapidly cooled to obtain an unstretched film having a thickness of 180 μm. After preheating the unstretched film at 90 ° C. for 8 seconds, it is stretched 1.6 times at 80 ° C. in the transverse direction and 2.5 times at 75 ° C., and then heat-treated at 73 ° C. for 10 seconds to have a thickness of 45 °
A μm heat-shrinkable polyester film was obtained. Table 1 shows the physical property values of the obtained film.

Comparative Example 4 By the same polymerization method as in Example 1, 83 mol% of terephthalic acid component, 17 mol% of 2,6-naphthalenedicarboxylic acid component, 83 mol% of ethylene glycol component and 15 mol% of butanediol component 2 mol% of polytetramethylene glycol (molecular weight 650) component
Was obtained. This copolymerized polyester had an intrinsic viscosity of 0.70 dL / g. This polyester was melt-extruded at 280 ° C. and then rapidly cooled to a thickness of 18
An unstretched film of 0 μm was obtained. The unstretched film is
After preheating at 05 ° C for 8 seconds, it is stretched in the transverse direction at 85 ° C by 2.5 times and further at 90 ° C by 1.6 times, and then heat-treated at 73 ° C for 10 seconds to obtain a heat-shrinkable polyester film having a thickness of 45 µm. Was. Table 1 shows the physical property values of the obtained film.

[0050]

[Table 1]

[0051]

The heat-shrinkable polyester film of the present invention has excellent shrink finish in a wide temperature range from low to high temperatures, particularly in a low temperature range, and has beautiful shrinkage with very few shrinkage spots, wrinkles and distortions. It has a finished appearance and excellent tear resistance, and is suitably used for applications such as shrink labels, cap seals, and shrink wraps.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B29K 105: 02 B29K 105: 02 B29L 7:00 B29L 7:00 C08L 63:02 C08L 63:02 (72) Inventor Sato Manki 2-1-1 Katata, Otsu-shi, Shiga Prefecture Toyobo Co., Ltd. Research Laboratory (72) Inventor Jikao Morishige 2-1-1 Katata, Otsu-shi, Shiga Prefecture Toyobo Research Co., Ltd. (72) Invention Person Nori Tabota 344 Maebata, Kizu, Inuyama-shi, Aichi Prefecture F-term in the Inuyama Plant of Toyobo Co., Ltd. 4F071 AA45 AF20Y AF61Y AH06 BA01 BB06 BB08 BB09 BC01 4F210 AA24 AE01 AG01 RC02 RG01 RG04 RG43 4J05 AB03 AD01 AD10 AE03 BA02 BA03 BA05 BA07 BA08 BA10 BB13A BD05A BD07A BF09 BF18 BF25 BF26 CA01 CA02 CA04 CA05 CA06 CB05A CB06A CC03A CC06A CD04 CH06 EB05A FC05 J08FC35 FC36 HA01 HB01 HB03J1J06JF13 J06 JF573 KB04 KB05 KE 02 KE03 KE05

Claims (3)

[Claims] (1) It is made of polyester and has a size of 6 in the main shrinkage direction.
The tan δ value of dynamic viscoelasticity at 0 ° C. is 0.05 or more,
The temperature at which the tan δ value becomes the maximum is 65 to 80 ° C.,
The maximum value of tan δ is 0.40 or more,
A heat-shrinkable polyester film, wherein the heat-shrinkage rate in the main shrinkage direction after the treatment for 0 seconds is 30% or more, and the initial rupture rate in a direction perpendicular to the main shrinkage direction is 0%. 2. The film has a heat shrinkage of 10% in a direction orthogonal to the main shrinkage direction after being treated in hot water at 80 ° C. for 10 seconds.
The heat-shrinkable polyester film according to claim 1, wherein: 3. The heat-shrinkable polyester film according to claim 1, wherein the polyester comprises at least one of a dimer acid component and / or a dimer diol component.