JP2001288283A - Heat-shrinkable polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-shrinkable polyester film which has excellent shrink characteristics in a wide temperature range of from high temperatures to low temperatures, particularly in a low temperature range and extremely reduces generation of a shrinkage spot, a crease, a distortion, and a vertical sink mark, and further is suitable in the use of labels having excellent breakage resistance as well. SOLUTION: The heat-shrinkable polyester film is composed of a polyester, and has a tan δ value of the dynamic viscoelasticity at 60 deg. to the major shrinkage direction of >=0.05, a temperature, at which the tan δ value reaches a maximum, of 65-80 deg.C and its tan δ maximum value of >=0.40, and a heat shrinkage in the major shrinkage direction after the treatment in hot water at 80 deg.C for 10 seconds of >=30%.

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,
BACKGROUND ART A heat-shrinkable stretched film made of a vinyl chloride resin, a polystyrene resin, a polyester resin, or the like is used as a label for various containers such as a polyethylene terephthalate (PET) container, a polyethylene container, and a glass container.

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.Furthermore, when coating and shrinking the body of containers such as PET bottles, polyethylene bottles, glass bottles, letters and designs printed on the film before shrinkage after shrinkage There were problems such as distortion and insufficient adhesion of the film to the container. 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.

[0007] When coating shrinkage occurs on an industrial production scale, a heat-shrinkable film processed into a form such as a label, tube or bag is attached to a container and then heat-shrinked by blowing steam. In general, a shrink tunnel of a type (steam tunnel) or a type of shrink tunnel of a type that blows hot air to shrink heat (hot air tunnel) is placed on a belt conveyor and 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. Another object of the present invention is to provide a heat-shrinkable polyester film suitable for excellent 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 dynamic viscoelasticity tan δ value of at least 0.15 at 65 ° C. in the main shrinkage direction. , The temperature at which the tanδ value is the maximum is 65
~ 100 ° C, the maximum value of tan δ is 0.40 or more, and the heat shrinkage in the main shrinkage direction after the treatment in hot water of 80 ° C for 10 seconds is 30.
% Or more.

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, 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, it is preferable that the tan δ value of the dynamic viscoelasticity at 60 ° C. in the main shrinkage direction is 0.05 or more. The heat-shrinkable polyester film having the above-mentioned properties has excellent shrink finish, particularly in a low temperature range, and can provide a beautiful shrink finish appearance with very few shrinkage spots, wrinkles, and distortions.

In this case, it is preferable that the temperature at which the tan δ value of the dynamic viscoelasticity in the main shrinkage direction becomes the maximum is 65 ° C. or more and less than 80 ° C. The heat-shrinkable polyester film having the above-mentioned properties has excellent shrink finish, particularly in a low temperature range, and can provide a beautiful shrink finish appearance with very few shrinkage spots, wrinkles, and distortions.

In this case, it is preferable that the initial rupture rate in the direction orthogonal to the main shrinkage direction is O%.

In this case, the heat shrinkage in the direction perpendicular 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 properties has excellent shrink finish in a wide temperature range from a low temperature to a high temperature, and can provide 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.

[0018]

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 of at least 0.15 at 65 ° C. in the main shrinkage direction, as 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.
The tan δ value of dynamic viscoelasticity in the main contraction direction at low temperature is a factor that affects the occurrence of shrinkage spots, wrinkles, distortions, etc. during contraction,
In particular, if the tan δ value of the dynamic viscoelasticity in the main shrinkage direction is 0.15 or more at 65 ° C., the occurrence of defects such as shrinkage spots, wrinkles, and distortion is extremely reduced in the process of industrial production in which heat shrinks in a shrink tunnel. . The tan δ value of the dynamic viscoelasticity in the main shrinkage direction is more preferably 0.20 or more at 65 ° C. Here, the tan δ value is obtained by applying a sinusoidal stress to a sample and calculating a storage elastic modulus (G ′) and a loss elastic modulus (G ″) from a delay of a sinusoidal strain as a response, and tan δ = G ′ / G Represents the value defined in ". Furthermore, the tan δ value of the dynamic viscoelasticity in the main shrinkage direction is 0.05 at 60 ° C.
As described above, it is particularly preferably 0.10 or more. At this time, the low-temperature shrinkability is particularly excellent, and the shrink finish is particularly good.

Further, in the present invention, it is necessary that the temperature at which the tan δ value of the dynamic viscoelasticity in the main shrinkage direction becomes the maximum is 65 ° C. or more and 100 ° C. or less. 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 becomes poor, and the physical properties of the film tend to change over time. For example, when stored at room temperature for a long time, the shrinkage at low temperatures of 70 ° C or less decreases,
A problem occurs in that the shrinkage finish is deteriorated. Furthermore, ta
When the temperature at which the nδ value becomes the maximum exceeds 100 ° C., the shrinkage finish in a low temperature range, which is a feature of the present invention, becomes poor. Further, the temperature at which the tan δ value of the dynamic viscoelasticity in the main shrinkage direction becomes maximum is preferably 65 ° C. or more and less than 80 ° C. At this time, the low-temperature shrinkability is particularly excellent, and the shrink finish is particularly good.

Further, in the present invention, in the main contraction direction,
It is necessary that the maximum value of tan δ is 0.4 or more. tanδ
When the maximum value is less than 0.4, since the crystallinity of the polyester constituting the heat-shrinkable polyester film becomes too high, 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 organic solvents, the maximum tan δ value in the main shrink direction is 0.6 or more,
Further, it is preferably 0.8 or more.

In the present invention, in the main shrinking direction,
It is necessary that the heat shrinkage after the treatment in hot water at 10 ° C. for 10 seconds is 30% or more. If the heat shrinkage in hot water at 80 ° C. is less than 30%, shrinkage is insufficient, resulting in poor shrink finish. In order to obtain more stable shrink finish appearance,
The thermal shrinkage after treatment for 10 seconds in 80 ° C hot water in the main shrinkage direction is 40
% Or more, more preferably 50% or more.

In the present invention, it is preferable that the initial rupture rate in the direction perpendicular to the main shrinkage direction is 0%. If the initial rupture ratio exceeds 0%, the tear resistance of the film becomes poor. In a shrinkable polyester film, the molecules are oriented in the main shrinkage direction, so if the tear resistance deteriorates, it tends to tear along the orientation direction of the molecules, and the film is stretched by the tension in the processing steps such as printing and tubing. There is a problem that breakage occurs and the operability of processing decreases.

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. When the heat shrinkage in the direction orthogonal to the main shrinkage direction exceeds 10%, poor shrinkage finish (vertical shrinkage) occurs due to shrinkage in the direction orthogonal to the main shrinkage direction. To obtain more stable shrink finish,
The heat shrinkage after treatment in hot water at 80 ° C. for 10 seconds in a direction orthogonal to the main shrinkage direction is preferably 7% or less, more preferably 5% or less, and particularly preferably 2% 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 preferably has a thickness of 10 to 200 μm, and has a thickness of 20 to 200 μm.
100 μm is more preferred.

The polyester forming the heat-shrinkable polyester film of the present invention comprises, as main components, a dicarboxylic acid component comprising an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid or an ester-forming derivative thereof and a polyhydric alcohol component. is there. As the dicarboxylic acid component, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene-1,4 or 2,6-dicarboxylic acid, 5
-Sodium sulfoisophthalic acid and the like. In addition, examples of these ester derivatives include derivatives such as dialkyl esters and diaryl esters. Examples of the aliphatic dicarboxylic acid include dimer acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid, and succinic acid. Further, an oxycarboxylic acid such as p-oxybenzoic acid, or a polyvalent carboxylic acid such as trimellitic anhydride or hiromellitic anhydride may be used in combination, if necessary. Further, as the polyhydric alcohol component, ethylene glycol, diethylene glycol,
Dimer diol, propylene glycol, triethylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2
-Methyl-1,5-pentanediol, 2,2-diethyl-1,
3-propanediol, 1,9-nonanediol, alkylene glycol such as 1,10-decanediol, ethylene oxide adduct of bisphenol compound or its derivative, trimethylolpropane, glycerin, pentaerythritol, polyoxytetramethylene glycol, polyethylene Glycol and the like. In addition, epsilon gaprolactone 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,
Since the tan δ value of the dynamic viscoelasticity at 60 ° C. in the main shrinkage direction can be increased while maintaining the tear resistance of the film, the film characteristics can be easily controlled. At this time, one or both of the dimer acid and the dimer diol may be contained, and the total content of the dimer acid and the dimer diol is 1 to 20 mol based on the total carboxylic acid component or the total polyhydric alcohol component. %, More preferably 1 to 15 mol%, particularly preferably 1 to 7 mol%. Dimer acid and 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 constitutional ratio is (1) :( 2) = 10: 90 to 90:10 It is. The dimer acid and the timer diol are preferably washed and refined with water.

[0027]

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 maximum, and the temperature and the tan δ maximum value are determined by using the above-mentioned polyester constituents,
By combining the film forming conditions, the film can be controlled within the target range of the present invention. Such a polyester may be a single polymer or a mixture of two or more poly earth stells. When two or more polyesters are used in combination, a mixed system of polyethylene terephthalate and a copolymerized polyester may be used,
A combination of copolymerized polyesters may be used.
Further, a combination with a homopolyester such as polybutylene terephthalate and polycyclohexylene dimethyl terephthalate may be used. Different secondary transition point (Tg)
A method of mixing two or more polyesters can also be an effective means for achieving the object of the present invention. As a specific configuration, for example, a dicarboxylic acid component is composed of terephthalic acid and isophthalic acid, and a diol component is ethylene glycol, dimer diol, and a polyester having a molecular weight of polytetramethylene glycol of 500 to 3000. 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 from 0.3 to 1.3 dL / g, particularly preferably from 0.5 to 1.3 dL / g in terms of intrinsic viscosity from the viewpoint of film forming properties.

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, manganese acetate, Mn salt such as manganese chloride, zinc chloride, Zn salt such as zinc acetate, cobalt chloride, Co salt such as cobalt acetate as a metal ion to the polyester is 300PPm or less, respectively for the polyester, It is also possible to add phosphoric acid or a phosphoric acid ester derivative such as phosphoric acid trimethyl ester or phosphoric acid triethyl ester in an amount of 200 PPm or less in terms of phosphorus (P).

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

At this time, the molar atomic ratio (P / M) between the total P amount (P) and the total metal ion amount (M) is considered in terms of heat resistance, river water resistance, and the like.
Is preferably 0.4 to 1.0. 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 polycondensed, a dimethyl ester of a dicarboxylic acid is used. 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 raw materials, that is, before transesterification or esterification, and the phosphoric acids are added before polycondensation reaction. Is preferably added.

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.

As described above, the tan at 65 ° C. in the dynamic viscoelasticity of the heat-shrinkable polyester resin film of the present invention is used.
δ value, tan δ maximum value, the temperature at which tan δ is the maximum, the method of setting the heat shrinkage in the main shrinkage direction in the main shrinkage direction after immersion treatment in 80 ° C. hot water for 10 seconds is not particularly limited, and a polyester forming a film is used. It can be achieved by controlling the constituent components of the system resin as described above or controlling the film forming conditions as described later, and these methods can be combined.

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 dryer or a vacuum dryer such as a hopper dryer, a paddle dryer, and the like.
It is melt extruded into a film at a temperature of ° 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 longitudinal direction, the film can be formed in the same manner as in the normal operation except that the stretching direction is changed by 90 degrees in the following method.

As a stretching method, when the main shrinkage direction is the horizontal direction, a transverse uniaxial stretching with a tenter may be mentioned as an example. However, when the stretching is performed in the lateral direction using a tenter, a preliminary process performed before the stretching step is performed. In the heating process, the film temperature
It is necessary to heat until Tg + O ° C to Tg + 60 ° C. Focusing on making the thickness distribution of the intended heat-shrinkable polyester film uniform, the heat conduction coefficient is O.
0013 calories / cm ² · sec · ° C) (0.0054 (J / c in SI unit)
m ² · sec · K)) It is preferable to carry out the process at a low wind speed.

The stretching in the transverse direction needs to be performed in a temperature range of Tg + 0 to + 40 ° C. so that the stretching ratio (the product of the stretching ratios of the respective stages when performing in multiple stages) is 2.3 to 7.3 times. . Further, it is preferable that the film is stretched so as to be 3.8 to 5.2 times. At this time, it is preferable that the first-stage stretching temperature is lower than the preheating temperature. Further, thereafter (in the case of multi-stage stretching, between any of the stretchings), it is preferable to perform a heat treatment at a temperature of 60 ° C. to 110 ° C. while stretching O to 15% or relaxing O to 15%. 40 ° C ~ 100 as required
Further heat treatment is preferably performed at a temperature of ° C.

In the biaxial stretching in the case where the main shrinkage direction is the horizontal direction and the film is also stretched in the longitudinal direction, successive biaxial stretching is performed.
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.

At this time, the film can be stretched 1.0 to 2.3 times or less, preferably 1.1 to 1.8 times, particularly preferably 1.1 to 1.4 times in the machine direction. The temperature in the longitudinal stretching is preferably Tg + 0 ° C. to Tg + 50 ° C., particularly preferably Tg + 10 ° C. to Tg + 40 ° C. Stretching in the machine direction can improve the tear resistance of the heat shrinkable film. However, 2.
When stretched more than 3 times, 80 ° C in the direction perpendicular to the main shrinkage direction
The heat shrinkage after 10 seconds of treatment in warm water tends to exceed 10%, which is not preferable as a condition for producing the film of the present invention.

Suppressing the internal heat generation of the film due to stretching,
Focusing on reducing the inward film temperature unevenness,
The heat transfer coefficient of the stretching process is O.OO09 calories / cm ² · sec · ° C
(0.0038 (J / cm ² · sec · K) in SI units) or more, preferably from O.O013 (0.0054 in SI units) to O.O020 calories / cm ²
・ Conditions of sec · ° C (0.0084 (J / cm ² · sec · K) in SI unit) are good.

An example of a particularly preferred stretching step will be described below. Prior to the stretching process, the coefficient of thermal conductivity is 0.0013 cal / c
m ² · sec · ° C) (0.0054 (J / cm ² · sec · K) in SI units)
Heating is performed at the following low wind speed until the film temperature becomes Tg + 0 ° C. to Tg + 60 ° C. Subsequent to the above preheating, the first stage of the horizontal stretching is performed at a preheating temperature of −30 ° C. to a preheating temperature of −20 ° C., and 1.8 to 2.3.
Stretch twice. First, as the first-stage stretching, the tan δ value at a low temperature increases due to the low-temperature stretching and the difference between the preheating temperature and the stretching temperature. Subsequent to the first-stage transverse stretching, the first-stage transverse stretching temperature is relaxed by 3 to 10% in the transverse direction within a temperature range of +3 to + 5 ° C. Next, in the temperature range of the first-stage transverse stretching temperature +5 to + 10 ° C.
The film is stretched so that the product of the primary transverse stretching ratio and the stretching ratio here becomes 3.8 to 4.2 times. By stretching at a high temperature with the relaxation step in between, the shrinkage stress and MDHS (shrinkage in the MD direction) are reduced. In the temperature range from the first-stage transverse stretching temperature to the first-stage transverse stretching temperature −5 ° C., the film is stretched 3 to 8% in the transverse direction. Finally, by performing the stretching step, the HS (shrinkage ratio in the TD direction) increases.

As described above, the present invention is achieved by a combination of the polyester composition of the film raw material and the stretching method.

The heat-shrinkable film of the present invention can have a layer such as an anti-fog layer laminated on the surface as required.

[0045]

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.
Measured under the conditions of 3 cm, displacement 0.25%, and frequency 10 Hz.The tan δ value at 60 ° C. was measured in the range of 60.0 to 60.4 ° C.
The δ value was quantified as a tan δ value at 60 ° C. 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 two values was used.

(2) Heat Shrinkage The film was cut into a square of 10 cm × 10 cm in a direction perpendicular to the stretching direction and treated in hot water of 80 ± 0.5 ° C. under no load for 10 seconds to be thermally shrunk. Thereafter, the longitudinal and lateral dimensions of the film were measured, and the heat shrinkage was determined according to the following equation (1). Heat shrinkage: (length before shrinkage-length after shrinkage) ÷ length before shrinkage × 100 (%) ... (1)

(3) Main shrinkage direction The film is cut into a 10 cm × 10 cm square in the stretching direction and a direction perpendicular to the stretching direction, and subjected to a heat-shrinkage treatment in hot water of 80 ° C. ± 0.5 ° C. for 10 seconds under no load. After this, the length and width dimensions of the film were measured, and the direction in which the heat shrinkage was large was defined as the main shrinkage direction.

(4) Shrink finish finish In a hot air-type heat shrink tunnel, pass through a hot air at 130 ° C. (wind speed 10 m / sec) for 10 seconds and place in a glass bottle (300 mL) with grass-colored, golden, and white inks. After mounting the color-printed heat-shrinkable film label, it was passed through and the shrinkage finish was visually determined. The heat-shrinkable film label was obtained by cutting a film into a rectangular shape, bonding the ends of the film with a solvent using 1,3-dioxolane and bonding them together (gluing margin: 5 mm), and forming a cylinder having a length of 110 mm and a folding diameter of 110 mm. Here, the circumferential direction is the main contraction direction, and the folding diameter is the length in the width direction when the cylindrical label is flattened. The rank of shrinkage finish was evaluated on a 5-point scale.5: Best finish (0 places) 4: Good finish (1 place) 3: Small shrinkage spots (2 places) 2: Shrinkage spots (3 spots) 55 places) 1: There were many contraction spots (6 places or more), and 4 or more was regarded as a pass level.

(5) Initial rupture rate The rupture elongation of the heat-shrinkable film was measured in the direction perpendicular to the main shrinkage direction according to JIS-C-2318 (the number of samples n = 20), and the rupture elongation was 5% or less. The number (x) of the samples was determined and calculated by the following equation (2). For the sample, a heat-shrinkable film was cut into a shape having a width of 15 mm and a length of 100 mm, and the longitudinal direction was defined as a direction orthogonal to the main shrinkage direction. Initial rupture rate = (x / n) × 100 (%)… (2)

Example 1 A stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux condenser was charged with dimethyl terephthalate 80 as a dicarboxylic acid component.
Mol%, dimethyl isophthalate 20 mol%, polyhydric alcohol component ethylene glycol 96 mol% and dimer diol 3 mol%, so that the polyhydric alcohol component is 2.2.2 times the dicarboxylic acid component in molar ratio. , 0.05 mol of zinc acetate as a transesterification catalyst (based on brewing ingredients)
A transesterification reaction was carried out while distilling off generated methanol out of the system. Thereafter, 1 mol% of polytetramethylene glycol (molecular weight: 650) (based on the brewing component) and 0.025 mol% of antimony trioxide (based on the brewing component) as a polycondensation catalyst were added to perform polycondensation. As a result, terephthalic acid component 8
A copolymerized polyester comprising 0 mol%, 20 mol% of isophthalic acid component, 96 mol% of ethylene glycol component, 3 mol% of dimer diol component and 1 mol% of polytetramethylene glycol (molecular weight 650) component was obtained. Here, 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 is stretched at a stretching temperature of 80.
The film was stretched 1.15 times in the machine direction at ℃. Next, at 103 ° C [heat transfer coefficient: 0.0011 cal / cm ² · sec · ° C (0.0045 J / cm ² · sec.
K)] for 8 seconds, followed by a first stage stretching in the transverse direction.
5 ℃ [Heat transfer coefficient: 0.0015cal / cm ²・ sec ・ ℃ (0.0062J /
cm ² · sec · K)], and relaxed by 6% at 78 ° C. in 3 seconds in the relaxation step, followed by 80 ° C. [heat transfer coefficient: 0.0014
cal / cm ² · sec · ° C (0.0060 J / cm ² · sec · K)], and the film was stretched in the transverse direction such that the total transverse stretching ratio became 4.0 times. Next, 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 43 μm.
At this time, the main contraction direction was the horizontal direction.

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% and ethylene glycol component 8
A copolyester comprising 8 mol%, neopentyl glycol component 10 mol%, and polytetramethylene glycol (molecular weight 650) component 2 mol% was obtained. This copolymerized polyester had an intrinsic viscosity of 0.72 dL / g. 280 of this polyester
After melt-extrusion at ℃, the mixture was rapidly cooled to obtain a 190 μm-thick unstretched film. The unstretched film was stretched 1.20 times in the machine direction at a stretching temperature of 78 ° C. Then at 105 ° C [heat transfer coefficient: 0.0
011 cal / cm ² · sec · ° C (0.0045 J / cm ² · sec · K)] After preheating for 8 seconds, the first stage stretching is continued in the horizontal direction at 75 ° C [heat transfer coefficient: 0.0015 cal / cm ² · sec. ° C (0.0062 J / cm ² · sec.
K)], 1.8%, relax 5% in 3 seconds at 76 ° C in the relaxation process, and subsequently 80 ° C [Heat transfer coefficient: 0.0014cal / cm ² · s
ec · ° C. (0.0060 J / cm ² · sec · K)] so that the total transverse stretching ratio was 4.1 times. Next, 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.

(Comparative Example 1) According to the same polymerization method as in Example 1, 97 mole% of terephthalic acid component and 3 mole of isophthalic acid component
% And ethylene glycol component 71.5 mol%, neopentyl glycol component 28 mol%, polytetramethylene glycol
(Molecular weight: 650) A copolymerized polyester composed of 0.5 mol% of the 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 obtain an unstretched film having a thickness of 195 μm. The unstretched film was preheated at 105 ° C for 9 seconds, stretched 4.3 times at 83 ° C in the transverse direction, and then heat-treated at 75 ° C for 10 seconds to obtain a heat-shrinkable polyester film having a thickness of 45 µm.

Comparative Example 2 By the same polymerization method as in Example 1, 92 mol% of terephthalic acid component and 8 mol of isophthalic acid component
%, An ethylene glycol component of 77 mol% and a 1,4-butanediol component of 23 mol%.
This copolymerized polyester had an intrinsic viscosity of 0.70 dL / g.
This polyester was melt-extruded at 280 ° C. and then quenched to obtain an unstretched film having a thickness of 180 μm. The unstretched film
After preheating at 95 ° C for 8 seconds, 2.3 times at 80 ° C in the horizontal direction, and further at 85 ° C
Stretched 1.7 times, then heat treated at 85 ° C for 15 seconds to a thickness of 4
A 4 μm heat-shrinkable polyester film was obtained.

Comparative Example 3 By a polymerization method similar to that in Example 1, terephthalic acid component 62 mol%, isophthalic acid component 38 mol%, ethylene glycol component 78 mol%, butanediol component 21 mol%, polytetramethylene glycol (Molecular weight 65
0) A copolymerized polyester consisting of 1 mol% of the component was obtained. This copolymerized polyester had an intrinsic viscosity of 0.70 dL / g. This polyester is melt-extruded at 280 ° C and quenched to a thickness of 180
A μm unstretched film was obtained. 90 ° C the unstretched film
After preheating for 8 seconds at 1.6 ° C at 80 ° C in the horizontal direction, and 2.5 times at 75 ° C
Stretched twice, then heat treated at 73 ° C for 10 seconds to a thickness of 45 μm
Was obtained.

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 and 83 mol% of ethylene glycol component,
A copolymerized polyester comprising 15 mol% of a butanediol component and 2 mol% of a polytetramethylene glycol (molecular weight: 650) component was obtained. This copolyester has an intrinsic viscosity of 0.70 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 105 ° C for 8 seconds,
The film was stretched 1.90 times at 90 ° C., and then heat-treated at 73 ° C. for 10 seconds to obtain a heat-shrinkable polyester film having a thickness of 45 μm.

EXAMPLE 3 28 mol of dimethyl terephthalate as a dibasic acid component was placed in a stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux condenser.
%, Dimethyl naphthalate 72 mol%, glycol component 88 mol% ethylene glycol and dimer diol 11 mol%
The mixture was charged 2.2 times, and a transesterification reaction was carried out using 0.05 mol% of zinc acetate (based on the brewing component) as a transesterification catalyst while distilling off generated methanol out of the system. Thereafter, 1 mol% of polytetramethylene glycol (molecular weight: 650) (based on the brewing component) and 0.025 mol% of antimony trioxide (based on the brewing component) as a polycondensation catalyst were added to perform polycondensation. As a result, 28 mol% of terephthalic acid component, 72 mol% of 2,6-naphthalenedicarboxylic acid component, 88 mol% of ethylene glycol component, 11 mol% of dimer diol component, and 1 mol% of polytetramethylene glycol (molecular weight 650) component A copolymerized polyester was obtained. This copolymerized polyester had an intrinsic viscosity of 0.69 d1 / g. This Polyester
After being melt-extruded at 280 ° C., it was rapidly cooled to obtain an unstretched film having a thickness of 180 μm. The unstretched film is stretched at a stretching temperature of 80 ° C. [heat transfer coefficient: 0.0201 cal / cm ² · sec · ° C. (0.0837 J / cm ² · se
c · K)] and stretched 1.15 times in the machine direction. Then 103 ℃
[Heat transfer coefficient: 0.0011 cal / cm ² · sec · ° C (0.0045 J / cm ²
· Sec · K)] for 8 seconds, and then as the first stage stretching in the transverse direction at 75 ° C [Heat transfer coefficient: 0.0015 cal / cm ² · sec · ° C (0.00
62J / cm ² · sec · K)], and a 6% relaxation step at 78 ° C for 3 seconds at 78 ° C.
° C. [heat transfer ^{coefficient: 0.0014cal / cm 2 · sec ·} ℃ (0.0060J / c
m ² · sec · K)] in stretched to a total of 4.0 times, and then at 73 ° C. 5
Heat treatment was carried out for 6 seconds while elongating% to obtain a heat-shrinkable polyester resin film having a thickness of 43 μm.

Example 4 By the same polymerization method as in Example 3, terephthalic acid component 51 mol%, isophthalic acid component 5 mol%, 2,6-naphthalenedicarboxylic acid component 35 mol%, dimer acid component 9 mol% And 89 mol of ethylene glycol component
%, A neopentyl glycol component of 10 mol%, and a polytetramethylene glycol (molecular weight 650) component of 1 mol% were obtained. This copolymerized polyester had an intrinsic viscosity of 0.70 d1 / 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 at a stretching temperature of 78 ° C. [heat transfer coefficient:
0.0201 cal / cm ² · sec · C (0.0837 J / cm ² · sec · K)] and stretched 1.20 times in the machine direction. Then, then at 105 ° C [heat transfer coefficient: 0.0011 cal / cm ² · sec · ° C (0.0045 J / cm ² · se
c ・ K)] and preheat for 8 seconds, then at 75 ℃
[Heat transfer coefficient: 0.0011 cal / cm ² · sec · ° C (0.0045 J / cm ²
· Sec · K)] and then a relaxation process of 5% at 78 ° C, followed by a second stage stretching at 80 ° C [heat transfer coefficient: 0.0
015 cal / cm ² · sec · ° C (0.0062 J / cm ² · sec · K)], stretched to a total of 4.1 times, and then heat-treated at 73 ° C for 6 seconds with 5% elongation. A polyester resin film was obtained.

Example 5 By the same polymerization method as in Example 3, terephthalic acid component 30 mol%, 2,6-naphthalenedicarboxylic acid component 70 mol%, ethylene glycol component 89 mol%, dimer diol component 10 mol %, And 1 mol% of a polytetramethylene glycol (molecular weight: 650) component were obtained. This copolyester has intrinsic viscosity
0.70d1 / g. This polyester was melt-extruded at 280 ° C. and rapidly cooled to obtain an unstretched film having a thickness of 400 μm.
The unstretched film is heated to 80 ° C. [heat transfer coefficient: 0.0201 cal / cm ²
・ Sec ・ ℃ (0.0837J / cm ²・ sec ・ K)], stretch 2.3 times in the machine direction, 105 ℃ [Heat transfer coefficient: 0.0011cal / cm ²・ sec ・ ℃
^{(0.0045J / cm 2 · sec ·} K)] in 8 seconds after preheating, in the transverse direction 8
5 ℃ [Heat transfer coefficient: 0.0015cal / cm ²・ sec ・ ℃ (0.0062J /
cm ² · sec · K)] in 2.5-fold and then through a 5% relaxation step at 88 ° C., further 90 ° C. [heat transfer coefficient: 0.0016cal / cm ² · sec ·
° C (0.0065 J / cm ² · sec · K)] and stretched 1.6 times.
Heat treatment was performed for 10 seconds at 5 ° C. while elongating 5% to obtain a heat-shrinkable polyester resin film having a thickness of 43 μm.

Comparative Example 5 By the same polymerization method as in Example 3, 100 mol% of the terephthalic acid component, 68 mol% of the ethylene glycol component, 31 mol% of the neopentyl glugol component,
1 mol% of polytetramethylene glycol (molecular weight 650) component
Was obtained. This copolymerized polyester had an intrinsic viscosity of 0.70 d1 / g. This polyester was melt-extruded at 280 ° C. and then rapidly cooled to obtain an unstretched film having a thickness of 195 μm. The unstretched film is heated at 110 ° C. [heat transfer coefficient: 0.0011 cal / cm ² · sec · ° C. (0.0045 J / cm ² · sec.
K)] for 8 seconds, then 83 ° C in lateral direction [Heat transfer coefficient: 0.00
4.5 at 11 cal / cm ² · sec · ° C (0.0045 J / cm ² · sec · K)]
Stretched twice and then heat treated at 70 ° C for 10 seconds to a thickness of 43μ
m of a heat-shrinkable polyester resin film was obtained.

Comparative Example 6 By the same polymerization method as in Example 3, 8 mol% of terephthalic acid component, 92 mol% of 2,6-naphthalenedicarboxylic acid component, 90 mol% of ethylene glycol component, 1,4-butane A copolymerized polyester comprising 10 mol% of a diol component was obtained. This copolymerized polyester had an intrinsic viscosity of 0.68 d1 / g. This polyester was melt-extruded at 280 ° C. and then quenched to obtain an unstretched film having a thickness of 180 μm. 105 ° C [heat transfer coefficient: 0.0011cal
/ cm ² · sec · ° C (0.0045 J / cm ² · sec · K)] for 8 seconds, then 90 ° C in the horizontal direction [Heat transfer coefficient: 0.0011 cal / cm ² · sec.
° C (0.0045 J / cm ² · sec · K)] 2.3 times, and 85 ° C
[Heat transfer coefficient: 0.0011 cal / cm ² · sec · ° C (0.0045 J / cm ²
.Sec.K)], and then heat-treated for 15 seconds while stretching at 90 ° C. by 5% to obtain a heat-shrinkable polyester resin film having a thickness of 46 μm.

Example 6 According to the same polymerization method as in Example 3, terephthalic acid component 78 mol%, isophthalic acid component 22
Thus, a copolymerized polyester comprising 81 mol% of an ethylene glycol component, 18 mol% of a butanediol component, and 1 mol% of a polytetramethylene glycol (molecular weight: 650) component was obtained.
This copolymerized polyester had an intrinsic viscosity of 0.67 d1 / 9.
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
90 ° C [Heat transfer coefficient: 0.0015cal / cm ² · sec · ° C (0.0062J /
cm ² · sec · K)] in 8 seconds after preheating, 80 ° C. in the transverse direction [heat transfer ^{coefficient: 0.0011cal / cm 2 · sec ·} ℃ (0.0045J / cm 2 · sec
・ K)] 1.6 times, and 75 ° C [Heat transfer coefficient: 0.0014cal /
^{cm 2 · sec · ℃ (0.0060J} / cm 2 · sec · K)] in 2.5-fold stretching, then to obtain a heat-shrinkable polyester resin film having a thickness of 45μm by a 10 seconds heat treatment at 60 ° C..

The dimer acid used was "Pripol 1009" manufactured by Unichema, and the dimer diol used was "HP-1000" manufactured by Toa Gosei Chemical Co., Ltd.

Table 1 shows the physical property values of the obtained film.

[Table 1]

[0065]

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) B29L 7:00 B29L 7:00 C08L 67:00 C08L 67:00 (72) Inventor Morikashi Jikao Katata, Otsu City, Shiga Prefecture 2-1-1, Toyobo Co., Ltd. Research Laboratory (72) Inventor Nori Tabota 344 Maebata, Kizu, Oaza, Inuyama, Aichi Prefecture Inuyama Plant, Toyobo Co., Ltd.

Claims (6)

[Claims] (1) It is made of polyester and has a main shrinkage direction of 65%.
The tan δ value of the dynamic viscoelasticity at 0.15 ° C. is 0.15 or more, and the temperature at which the tan δ value is the maximum is 65 ° C. or more and 100 ° C. or less, and the t
A heat-shrinkable polyester film having an an δ maximum value of 0.40 or more and a heat shrinkage rate in the main shrinkage direction of 30% or more after treatment in hot water at 80 ° C for 10 seconds. 2. The main shrinkage direction of the film according to claim 1.
A heat-entrapping polyester film having a dynamic viscoelasticity tan δ value at 0 ° C of 0.05 or more. 3. The temperature at which the tan δ value of dynamic viscoelasticity in the main shrinkage direction of the film according to claim 1 or 2 is 65 ° C.
As described above, the heat-entrapping polyester film having a temperature of less than 80 ° C. 4. A heat-shrinkable polyester film, characterized in that the film according to any one of claims 1, 2, and 3 has an initial rupture rate of 0% in a direction perpendicular to the main shrinkage direction. 5. The heat shrinkage in a direction orthogonal to the main shrinkage direction of the film according to any one of claims 1, 2, 3, and 4 after being treated in hot water at 80 ° C. for 10 seconds. A heat-entrapping polyester film characterized by the following. 6. The heat-shrinkable polyester according to claim 1, wherein the polyester comprises at least one component of a dimer acid component and / or a dimer diol component. System film.