JP2008030366A - Heat-shrinkable polyester film roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-shrinkable polyester film roll having processabilities as a beverage container label, solving the problem due to a deficiency of slipperiness, excellent in openabilities at the time of cutting of the label, and also uniform in other physical properties, and also to provide its manufacturing method. <P>SOLUTION: The heat-shrinkable polyester film roll is obtained by winding a heat shrinkable polyester film and characterized in that the heat shrinkage ratio in the maximum heat shrinkage direction is 50% or above when a plurality of samples cut into a square shape of 10×10 cm from the film are immersed in hot water of 95°C for 10 sec and drawn up and subsequently immersed in water of 25°C for 10 sec to be drawn up, the coefficients (μd) of dynamic friction of the mutual surfaces of the mutual surfaces of the film samples cut from the long film under a predetermined condition is 0.28 or below with respect to all of the samples, and the coefficient (μd) of the friction of mutual other surfaces is 0.35 or below with respect to all of the samples. The heat shrinkable polyester film roll contains ethylene terephthalate as a main constituent component and is characterized in that the ethylene terephthalate unit is 70 mol% or above. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a film roll formed by winding a heat-shrinkable polyester film suitable for labeling, and winding a heat-shrinkable polyester film having excellent opening after label cutting in which the film is labeled. It relates to the film roll to be taken. Moreover, it is related with the film roll formed by winding up the heat-shrinkable polyester-type slippery film with the favorable slidability of the outer surface when used as a label for beverage bottles.

In recent years, for the purpose of packaging to improve the appearance of packaging, packaging to avoid direct impact of contents, label packaging that protects glass bottles or plastic bottles and displays products, etc.
A heat-shrinkable plastic film having a property of shrinking by heating is widely used. Plastic materials used for these purposes include stretched films such as polyvinyl chloride films, polystyrene films, and polyester films. Labels are used in various containers such as polyethylene terephthalate (PET) containers, polyethylene containers, and glass containers. And used for the purpose of cap seals or integrated packaging.

  In order to produce labels and the like, the following methods are usually employed. That is, the raw polymer is continuously melt extruded to produce an unstretched film. Next, stretching is performed to obtain a film roll. While feeding out the film from this film roll, it is slit to a desired width and wound into a roll again. Subsequently, character information such as various product names and designs are printed. After the printing is finished, the left and right end portions of the film are overlapped and joined by means such as solvent adhesion to produce a tube-like body (tubing process). The slit process and the printing process may be reversed in order. The obtained tube-shaped body is appropriately cut into a length and processed into a form such as a label or a bag.

  And the inside of the shrink tunnel (steam tunnel) of the type that covers the label or bag etc. on the container and blows and heat shrinks by steam, and the shrink tunnel (hot air tunnel) of the type that blows hot air and heat shrinks, A final product (labeled container) is obtained by passing it on a belt conveyor or the like, and heat-shrinking a label, a bag, or the like so as to be in close contact with the container.

  Polyvinyl chloride film has excellent shrinkage properties, but has low heat resistance, and also has problems such as generation of hydrogen chloride gas during incineration and causing dioxins. Further, when a heat-shrinkable vinyl chloride resin film is used as a shrinkable label for a PET container or the like, there is a problem that the label and the container must be separated when the container is recycled.

On the other hand, a polystyrene film can be evaluated for its good finished appearance after shrinkage, but it is poor in solvent resistance, so an ink with a special composition must be used for printing. In addition, polystyrene resins need to be incinerated at a high temperature and have a problem that a large amount of black smoke and off-flavor are generated during incineration.
These problem-free polyester films are useful as shrink labels instead of polyvinyl chloride films and polystyrene films.

However, the conventional heat-shrinkable polyester film has been required to be further improved in its properties. When beverages sold in vending machines are sold with vending machines using conventional polyester film as labels, the slipperiness of the labels is insufficient and clogging in vending machines, that is, the product does not pass through the passage. Since there were problems such as failure to reach the exit and multiple discharge of products, it is a user-side request to improve the slipperiness of the film. In order to solve this problem, a method of laminating a layer having good slipperiness on the film surface has been made (see, for example, Patent Document 1).
JP 2002-196677 A

  However, this is due to the post-processing of the film, and there are problems in terms of cost, and there are still problems such as wear debris generated due to rubbing between the roll and the like in the processing step and the productivity, thereby reducing productivity.

On the other hand, it was considered effective to laminate a thin film layer with good slipperiness on the film production line, but in that case, depending on the composition of the polyester film, there is a problem that the adhesiveness is insufficient in the tube processing There were many cases. When a label is produced from a heat-shrinkable polyester film, it is often adhered using a solvent. For this adhesion, it is preferable that a solvent such as 1,3-dioxolane or tetrahydrofuran is applied to one surface of the film and the other surface of the film is pressure-bonded to the applied surface. When this adhesive strength is insufficient, there is a possibility that the label adhesive part may be peeled off when the label is thermally contracted or when the beverage bottle is handled.
For this reason, there has been a demand for a heat-shrinkable polyester film having a thin film layer with good slipperiness as the outermost layer and good adhesion with a solvent.

  There was also a problem after cutting the tube-like body into a label. This is a problem that fusion or blocking occurs at the cut portion, causing trouble when opening and reducing productivity.

  In the present invention, a heat-shrinkable label, a bag, etc. are manufactured from a roll wound with a long film, and these are put on a container and thermally contracted to provide a labeled container product. An object of the present invention is to provide a heat-shrinkable polyester film roll that can solve problems in the process and reduce the occurrence of trouble, and a method for producing the same.

The present invention is a film roll formed by winding a heat-shrinkable polyester film, and the heat-shrinkable polyester film has a gist in that the following requirements (1) to (3) are satisfied.
When the end of the film in the steady region where the film properties are stable in the length direction of the film is the first end and the end of the end of the film is the second end, the second end A first sample cutout is provided within 2 m inside the part, a final cutout is provided within 2 m inside the first end, and a sample cutout is provided approximately every 100 m from the first sample cutout. Each sample cut into a 10 cm × 10 cm square shape is immersed in warm water at 95 ° C. for 10 seconds and then pulled up and then immersed in water at 25 ° C. for 10 seconds. , 50% or more for all samples.
-For each sample cut out separately from each sample cut-out part described in (1) above, the dynamic friction coefficient (μd) between at least one surface of the cut-out samples is 0.28 or less in all samples, In addition, the same coefficient of friction (μd) between the other surfaces is 0.35 or less for all the samples.
-Ethylene terephthalate is the main constituent and the ethylene terephthalate unit is 70 mol% or more.
As a suitable achievement means, for example, it has a layer (B) made of a polyester resin in which polyethylene terephthalate is 40% by weight or more in all polyester resin components, and in one polyester outermost layer, in all polyester resin components, A layer (A) made of a polyester resin having a polyethylene terephthalate content of less than 40% by weight, and the other outermost layer adjacent to a layer (A) made of a polyester resin having a polyethylene terephthalate content of less than 40% by weight in all polyester resin components. It is a heat-shrinkable polyester film roll having a silicone component-containing layer.
That is, two polyester resin mixtures (B ′) in which polyethylene terephthalate is 40% by weight or more in all polyester resin components and two polyester resin mixtures (A ′) in which polyethylene terephthalate is less than 40% by weight in all polyester resin components. Melting and co-extrusion using a stand extruder to laminate (A) as an outer layer and (B) as an inner layer to obtain an unstretched polyester film or a uniaxially stretched polyester film as two types and three layers And a polyester-based heat-shrinkable film obtained by applying a coating liquid containing a silicone component on at least one surface and then biaxially stretching or uniaxially stretching the coated film, and a method for producing the same. When used as a beverage container label, it can be clogged with a vending machine. Sealed, it is possible to provide a heat-shrinkable polyester film roll having excellent opening properties after label cut.

  In order to produce a film roll in which an easy-sliding layer is formed in the present invention, the coating liquid for the easy-slip layer is applied to at least one surface of a melt-extruded unstretched polyester film or a uniaxially stretched polyester film, and then the coating is applied. An in-line coating method including a step of biaxially stretching or uniaxially stretching the film is preferable.

  The heat-shrinkable film roll of the present invention has extremely low occurrence of defects due to the occurrence of clogging in a vending machine due to slippage in the film roll and fluctuations in surface characteristics, It has excellent processability such as opening after label cutting and is very useful in industrial production.

  The heat-shrinkable polyester film roll of the present invention is formed by winding a heat-shrinkable polyester film. The film being wound must satisfy the following requirement (1).

(1) When the winding start end of the film in the steady region where the film properties are stable in the length direction of the film is the first end, and the end on the winding end is the second end, The first sample cutout portion is provided within 2 m inside the two end portions, and the final cutout portion is provided within 2 m inside the first end portion, and the sample cutout portion is provided approximately every 100 m from the first sample cutout portion. Each sample cut into a square shape of 10 cm × 10 cm was immersed in 95 ° C. warm water for 10 seconds and then pulled up and then immersed in 25 ° C. water for 10 seconds, and then the heat shrinkage in the maximum heat shrinkage direction The rate is 50% or more for all samples.

  First, the meaning of the requirement (1) “steady region where film properties are stable in the length direction of the film” will be described. The “steady region where the film physical properties are stable in the length direction of the film” is a region where the film forming process and the stretching process are stably performed during film production, and the film physical properties are almost uniform. In the present invention, in a long film obtained when the film forming process and the stretching process are operated in a stable steady state, characteristics such as heat shrinkage characteristics and slipperiness are made more uniform than conventional levels. Is the technical idea. In actual operation, during film production, the composition of the film may vary depending on the raw material supply method and film formation conditions.In the present invention, the film obtained when the raw material supply amount and film formation conditions are unstable is used. It does not require uniformization. For this reason, it is assumed that the sampling for evaluating the characteristics requiring homogenization is performed only in the region where the film forming process and the stretching process are operated in a stable steady state, that is, the “steady region”.

  Therefore, for example, if the film is about 10 m from the beginning of winding of the roll when the steady operation is not performed, sampling is not performed from this portion, and the 10 m from the beginning of winding is sampled as the first end of the film.

  The number of the steady regions (steady operation regions) is normally one place per film roll (one place over the entire film roll). However, since there may be a plurality of locations depending on the manufacturing situation, sampling is performed only from the steady region in this case. The steady region can be evaluated, for example, by measuring the thermal shrinkage rate in the maximum shrinkage direction of the film by a method described later. That is, the region where the heat shrinkage rate is within a range of about 20% (the difference between the maximum value and the minimum value of the heat shrinkage rate of a plurality of samples is within about 20%) may be regarded as the steady region.

  Subsequently, a sampling method will be described. For the film wound on one roll, when the end of the film in the steady region on the winding start side is the first end and the end of the winding end is the second end, the second end The first sample cutout portion is provided within 2 m from the first end portion, and the final cutout portion is provided within 2 m inside the first end portion, and the sample cutout portion is provided approximately every 100 m from the first sample cutout portion. By providing, samples are selected at approximately equal intervals over the entire length of the steady region of the film. Note that “about every 100 m” means that the sample may be cut out at about 100 m ± 1 m.

  The sampling method will be described in more detail. For example, when a heat-shrinkable film having a total length of a steady region and a length of 498 m is wound around a roll, the first sample A is placed within 2 m from the end of winding (second end) of the film. cut out. The area to be cut out is appropriately selected according to the physical property value to be measured. Subsequently, the second sample B is cut out at a distance of about 100 m from where the first sample A was cut out. In the same manner, the third sample C is cut out at about 200 m, the fourth sample D is cut out at about 300 m, and the fifth sample E is cut out at about 400 m. Here, since the remainder becomes shorter than 100 m, the sixth (final) sample F cuts out any portion within 2 m from the start of winding (first end) of the film.

  The requirement (1) of the present invention is that the thermal shrinkage rate in the maximum shrinkage direction of all the samples thus cut is 50% or more. If the heat shrinkage rate of the film is less than 50%, the heat shrinkage force of the film is insufficient, and when the label is made from the film and the container is covered and shrunk, it does not adhere to the container, resulting in poor appearance. It is not preferable. A more preferable heat shrinkage rate is 52% or more, and further preferably 55% or more. On the other hand, if the thermal shrinkage rate is excessively high, an appearance defect such as a jumping of a label occurs due to abrupt shrinkage when the container is shrunk. The heat shrinkage rate is preferably 80% or less, more preferably 78% or less, and still more preferably 76% or less.

Here, the heat shrinkage rate in the maximum shrinkage direction means the heat shrinkage rate in the direction in which the sample is most contracted, and the maximum shrinkage direction is the length in the longitudinal direction or the transverse direction of the cut-out square sample. It is decided. Further, the thermal shrinkage rate (%) was obtained by immersing a sample of 10 cm × 10 cm in warm water at 95 ° C. ± 0.5 ° C. for 10 seconds in a no-load state and then thermally shrinking, and then 25 ° C. ± 0.5 The film was measured in accordance with the following formula after measuring the length in the longitudinal and lateral directions after being immersed in water at 10 ° C. for 10 seconds under no load condition (hereinafter, the heat shrinkage in the maximum shrinkage direction measured under these conditions). The rate is simply abbreviated as “heat shrinkage rate”).
Heat shrinkage rate = 100 × (length before shrinkage−length after shrinkage) ÷ (length before shrinkage)

  The requirement (2) of the present invention is that when the friction coefficient μd between the same surfaces of each sample separately cut out from each sample cutout part in the above requirement (1) is measured, the μd of all the samples is 0.28. The friction coefficient (μd) between the other surfaces is 0.35 or less for all the samples. The details of the sample sampling method are the same as those in the requirement (1).

  The long film satisfying the requirement (2) is excellent in slipperiness. This long film is excellent in slipperiness in the vending machine, particularly when used as a PET bottle label for beverages. For example, the contact area between the vending machine and adjacent products is large and clogged. Even if it is a square bottle which is easy to generate | occur | produce, generation | occurrence | production of clogging can be prevented. However, if the range of slipperiness is exceeded, the slipperiness becomes insufficient, and troubles such as clogging with vending machines occur. Moreover, it also shows that the opening property after cutting is excellent, and when cutting a tube-like body into a label, fusion or blocking can be prevented at the cutting portion.

  This indicates that a long film that satisfies the requirement of the friction coefficient μd between the first surfaces of requirement (2) is excellent in slipperiness. This long film is excellent in slipperiness in the vending machine, particularly when used as a PET bottle label for beverages. For example, the contact area between the vending machine and adjacent products is large and clogged. Even if it is a square bottle which is easy to generate | occur | produce, generation | occurrence | production of clogging can be prevented. However, if the range of slipperiness is exceeded, the slipperiness becomes insufficient, and troubles such as clogging with vending machines occur. The friction coefficient μd between the first surfaces of the film is 0.28 or less, preferably 0.26 or less, more preferably 0.24 or less. The lower limit of the dynamic friction coefficient μd between the first surfaces of the film is preferably 0.10 or more, more preferably 0.12 or more, from the viewpoint of preventing slippage.

    The long film that satisfies the requirement of the friction coefficient μd between the second surfaces of requirement (2) has moderate slipperiness and excellent workability. If this slippage range is exceeded, the slipperiness becomes insufficient, and printing and tubing workability deteriorates. The friction coefficient μd between the second surfaces of the film is 0.35 or less, preferably 0.31 or less, more preferably 0.28 or less. The lower limit of the dynamic friction coefficient μd between the first surfaces of the film is preferably 0.10 or more, more preferably 0.12 or more, from the viewpoint of preventing slippage.

  Requirement (3) is that ethylene terephthalate is the main component of the polyester resin component constituting the film, and the ethylene terephthalate unit is 70 mol% or more.

  The dynamic friction coefficient μd between the same surfaces of the film is a value measured in an environment of 23 ° C. and 65% RH in accordance with JIS K 7125.

  Next, constituent components of the polyester will be described. As the polyester-based resin, as a polyvalent carboxylic acid component, an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, or one or more of these ester-forming derivatives is used and polycondensed with a polyhydric alcohol component (copolymerization) Polyester can be used

  Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalene-1,4- or -2,6-dicarboxylic acid, and 5-sodium sulfoisophthalic acid. 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, and a polyvalent carboxylic acid such as trimellitic anhydride or pyromellitic anhydride may be used in combination as necessary. Among these, terephthalic acid, isophthalic acid, naphthalene-1,4- or -2,6-dicarboxylic acid is preferable. Examples of ester-forming derivatives include derivatives such as dialkyl esters, diaryl esters, and acid halides.

  Polyhydric alcohol components include ethylene glycol, diethylene glycol, dimer diol, 1,3-propanediol, triethylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 1,6-hexane Diol, 3-methyl 1,5-pentanediol, 2-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,9-nonanediol, 1,10-decanediol, etc. Alkylene glycol, an alkylene oxide adduct of a bisphenol compound or a derivative thereof, trimethylolpropane, glycerin, pentaerythritol, polyoxytetramethylene glycol, polyethylene glycol and the like. In addition, ε-caprolactone can be used for the synthesis of polyester.

The polyester contained in the raw material composition is composed of the acid component and the diol component. In order to adjust the polyester, one or more acid components are used to improve the properties as a heat-shrinkable film. Or it is preferable to use combining a diol component, and the kind and content of the monomer component combined are suitably determined based on a desired film characteristic, economical efficiency, etc.
The raw material composition contains one or more polyesters. When two or more kinds of polyesters are mixed, a mixture having a desired composition of a copolyester and a homopolyester is prepared. In general, copolymer polyester has a low melting point, so it is difficult to handle at the time of drying, so homopolyester (polyethylene terephthalate, polyethylene naphthalate, poly (1,4-cyclohexene diethylene terephthalate), etc.) and copolymer polyester are used. It is preferable to use a mixture.
As a preferred embodiment, any one of an ethylene terephthalate unit, a unit composed of neopentyl glycol and terephthalic acid, a unit composed of 1,4-cyclohexanedimethanol and terephthalic acid, butylene terephthalate, propylene terephthalate, and ethylene isophthalate More preferred embodiments of the polyester containing the above include ethylene terephthalate units, units composed of neopentyl glycol and terephthalic acid, units composed of 1,4-cyclohexanedimethanol and terephthalic acid, and butylene terephthalate units or propylene. Examples thereof include a polyester containing a terephthalate unit.
The effect on the film physical properties when the content of the ethylene terephthalate unit is increased includes the effect of making the film tough and not easily torn. Moreover, when the yield point stress is increased and the container is attached to a container or the like, adhesion to the container can be obtained. However, the increase tends to lower the solvent adhesiveness due to the application of a solvent such as 1,3-dioxolane and tetrahydrofuran and pressure bonding.

  The main constituent unit of polyester is preferably an ethylene terephthalate unit in view of film tear resistance, strength, heat resistance, and the like. In the present invention, it is necessary to select the ethylene terephthalate unit to be 70 mol% or more in 100 mol% of the constituent unit of the polyester raw material. By setting the ethylene terephthalate unit to 70 mol% or more, an effect of increasing the yield point stress by strengthening the above-mentioned film can be obtained, and the processing stability of the film can be enhanced. The ethylene terephthalate unit is preferably 71 mol% or more, more preferably 72 mol% or more. The upper limit of the ethylene terephthalate unit is not particularly limited, but is preferably 80 mol% or less from the viewpoint of ensuring solvent adhesion and an appropriate heat shrinkage rate. The ethylene terephthalate unit is preferably 79 mol% or less, and more preferably 78 mol% or less.

  The secondary constituent unit other than the ethylene terephthalate unit is recommended to be 5 mol% or more, preferably 7 mol% or more, more preferably 9 mol% or more, in 100 mol% of the polyester raw material constituent unit. . It is because it becomes possible to ensure the solvent adhesiveness and heat shrinkability of the film by introducing the amorphous improvement component to the above extent.

  That is, homopolyester or copolyester chips may be produced and the chips mixed. Even if homopolyesters having different compositions or a homopolyester and a copolyester are mixed, problems such as whitening of the film caused by poor compatibility do not occur. This is because the raw material polyester is heated considerably in the melt-kneading process in the extruder, so that a transesterification reaction occurs between the respective polyesters, and when extruded from the extruder, a mixture of copolymer polyesters having a similar composition is formed. It is because it will denature. This is confirmed from the fact that only one peak indicating the Tg of the film is observed.

  Polyesters can be produced by melt polymerization according to a conventional method, but the so-called direct polymerization method in which an oligomer obtained by directly reacting a polyvalent carboxylic acid component and a polyhydric alcohol component is polycondensed, a dimethyl ester of a polyvalent carboxylic acid. Examples include a so-called transesterification method in which a polycondensation is performed after a transesterification reaction between the product and a polyhydric alcohol component, and any production method can be applied. Moreover, the polyester obtained by another polymerization method may be sufficient. The degree of polymerization of the polyester is preferably 0.5 to 1.3 dl / g in terms of intrinsic viscosity.

  In addition to polymerization catalysts such as antimony oxide, germanium oxide, and titanium compounds, polyester such as magnesium acetate, magnesium chloride and other Mg salts, calcium acetate, calcium chloride, etc. Ca salt, manganese acetate, manganese chloride and other Mn salts, zinc chloride, zinc acetate and other Zn salts, cobalt chloride, cobalt acetate and other Co salts as metal ions for each of the resulting polyesters at 300 ppm (mass basis, the same applies hereinafter) ) Hereinafter, phosphoric acid or phosphoric acid ester derivatives such as phosphoric acid trimethyl ester and phosphoric acid triethyl ester may be added in an amount of 200 ppm or less in terms of phosphorus (P).

  If the total amount of metal ions other than the above polymerization catalyst is 300 ppm with respect to the polyester and the amount of P exceeds 200 ppm, not only the coloration of the polymer will be significant, but also the heat resistance and hydrolysis resistance of the polymer will be significantly reduced. .

  At this time, the mass ratio (P / M) of the total P amount (P) and the total metal ion amount (M) is 0.4 to 1.0 in terms of heat resistance, hydrolysis resistance, and the like. Is preferred. When the mass ratio (P / M) is less than 0.4 or exceeds 1.0, the film may be colored or coarse particles may be mixed in the film, which is not preferable.

  The timing of adding the above metal ions, phosphoric acid and derivatives thereof is not particularly limited. In general, metal ions are added at the time of raw material charging, that is, before transesterification or esterification, and phosphoric acids are added before polycondensation reaction. It is preferable to do this.

  Further, if necessary, fine particles such as silica, titanium dioxide, kaolin, calcium carbonate may be added, and an antioxidant, an ultraviolet absorber, an antistatic agent, a coloring agent, an antibacterial agent, etc. may be added. it can.

  Next, a preferable method for producing a long film exhibiting characteristics such as uniform heat shrinkage behavior and slipperiness over the entire length will be described.

  Generally, a heat-shrinkable polyester film is blended with two or more types / compositions of different polymers or a plurality of copolymerized monomer components as described above from the viewpoint of achieving both heat shrinkage properties and strength. For example, a method of introducing a secondary constituent unit in addition to the main constituent unit into the raw polymer to change the properties of the resulting film is employed. At this time, as a means for including one or more secondary constituent units in the film, a method of performing copolymerization and using this copolymer polymer alone and a method of blending different types of homopolymers or copolymer polymers There is.

  Also, when internally adding lubricants or antistatic agents, add them to any polymer (masterbatch), and adjust the amount of this polymer used to ensure the necessary amount of lubricant or antistatic agent. It is generally done.

In the system in which the copolymer is used alone, the amount of lubricant or the like hardly varies in the long film wound around the roll.
On the other hand, the blend method is widely used industrially because the film characteristics can be easily changed by simply changing the blend ratio, and it can be used for industrial production of various types of films. And in the case of such a polymer blend, since it has been found that fluctuations in the amount of lubricant, etc., and physical properties of the film wound on one roll are increased, each requirement specified in the present invention is satisfied. In order to obtain a film roll to be used, it is preferable to use the following method.

(I) Uniformization of chip shape In the blending method, usually, a plurality of raw material polymer chips having different compositions are blended in a hopper, a chip mixture is introduced into an extruder, and the polymer is melt-kneaded and extruded to form a film. To do. For example, when there are three types of polymers as raw materials, the respective polymer chips are supplied to three hoppers in a continuous or intermittent manner, and if necessary, via a buffer hopper, finally, immediately before the extruder or While mixing three types of polymer chips in a hopper immediately above (referred to as “final hopper” for convenience), raw material chips are quantitatively supplied to the extruder in accordance with the extrusion amount of the extruder to form a film. However, depending on the capacity or shape of the final hopper, the raw material segregation that the composition of the chips supplied from the final hopper to the extruder differs when the amount of chips in the final hopper is large and when the remaining amount is small. It was found that this phenomenon occurred. This problem is particularly noticeable when the shape or specific gravity of various polymer chips is different. If the material segregation phenomenon occurs and the composition of the polymer extruded from the extruder fluctuates accordingly, the heat shrink behavior of the heat shrinkable film to be produced will fluctuate. If only one of the chips contains a lubricant or an antistatic agent, the slipperiness of the long film varies as a result of segregation of raw materials.

  Therefore, when manufacturing a heat-shrinkable polyester film roll including a step of mixing and extruding a polymer having the largest amount of use and one or more other polymers having different compositions from this polymer, only the polymer composition is used. In addition, it is necessary to reduce fluctuations in the amount of lubricant, and as a means of reducing such fluctuations in the composition of the raw material composition, the raw material segregation phenomenon in the hopper can be achieved by combining the shapes of multiple types of polymer chips to be used. It is preferable to suppress.

  In order to produce a raw material chip for a polyester film, usually, after polymerization, a polymer in a molten state is taken out from the polymerization apparatus as a strand, immediately cooled with water, and then cut with a strand cutter. For this reason, the polyester chip usually has an elliptical column shape with an elliptical cross section. At this time, the average major axis (mm), the average minor axis (mm), and the average chip of the cross-sectional ellipse of the polymer chip of the most used amount are mixed as the polymer chip of the other polymer mixed with the most used polymer chip. It was found that the material segregation can be reduced by using those that are within ± 20% of the length (mm). It is more preferable to use those having an average value within a range of ± 15%.

  If there is a difference in the size of the chips, when the mixture of chips falls in the final hopper, small chips tend to fall first, so if the remaining amount of chips in the final hopper decreases, the ratio of large chips This increases the amount of raw material segregation. However, by using a chip within the above range, these raw material segregation can be reduced, and a long film having a uniform composition can be obtained.

  The raw material chips may be pre-mixed and then fed to the final hopper and the extruder via several intermediate (buffer) hoppers. When mixing multiple types of raw material chips, there is a method of mixing in a hopper using an apparatus that can continuously supply raw material chips, or a method of mixing in advance using a blender, etc. In the latter case, it is preferable to pay attention to the size of the raw material chips so that the raw material segregation does not occur when the mixture is discharged.

(Ii) Optimization of hopper shape An extruder is used to obtain a film, and optimization of the final hopper shape is also a preferable means for obtaining a long film having a uniform composition. That is, if the inclination angle of the funnel-shaped hopper is smaller than 60 °, only small chips will fall first and cause segregation of raw materials. By using a hopper with an inclination angle of 65 ° or more, a large chip can be easily dropped as well as a small chip, and the upper end of the contents (chip) descends in the hopper while maintaining a horizontal plane. Helps reduce raw material segregation. A more preferable inclination angle is 70 ° or more. The inclination angle of the hopper is an angle between the funnel-shaped hypotenuse and the horizontal line segment. A plurality of hoppers may be used upstream of the final hopper. In this case, the inclination angle is 65 ° or more, more preferably 70 ° or more in any hopper.

(Iii) Optimization of hopper capacity As a means for reducing raw material segregation in the hopper, optimizing the capacity of the hopper is also a preferable means. The proper capacity of the hopper is in the range of 15 to 120% by mass of the discharge amount per hour of the extruder. If the hopper has a capacity of about 15% by mass or more of the discharge amount, it is difficult to stably supply the raw material. If the hopper is too large, the raw material chip mixture remains in the hopper for a long time. The reason that the segregation of the chip may occur is the reason for setting the hopper capacity within the above range. The capacity of the hopper is more preferably in the range of 20 to 100% by mass of the discharge amount per hour of the extruder.

(Iv) Reduction of fine powder In order to obtain a long film having a uniform composition, it is also a preferable means to reduce the ratio of fine powder generated by scraping of raw material chips to be used. Since the fine powder promotes the occurrence of raw material segregation, it is preferable to remove the fine powder generated in the process and reduce the ratio of the fine powder contained in the hopper. The ratio of the fine powder contained is preferably controlled within 1% by mass and more preferably within 0.5% by mass in 100% by mass of the raw material throughout all steps until the raw material chips enter the extruder. preferable. Specifically, the fine powder may be removed by manufacturing a chip with a strand cutter and then passing it through a sieve, or when passing a raw material chip by air, for example, through a cyclone air filter.

  Since the composition of the film extruded from the extruder by the means (i) to (iv) is uniform over the entire long film, the lubricant and antistatic agent added to the chip are also long. The amount is uniformly present throughout the film, and the requirements of the present invention can be satisfied.

  What can be used as an additive-type lubricant / antistatic agent is various compounds described later as those that can be used in a coating solution for forming a slippery layer. Particle types such as inorganic particles, organic salt particles, and crosslinked polymer particles are also effective for imparting slipperiness.

  Examples of the inorganic particles include calcium carbonate, kaolin, talc, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, and riotium fluoride. Etc. In particular, in order to obtain a film having a lower haze while obtaining good handling properties, the inorganic particles are preferably aggregated silica particles formed by agglomerating primary particles. Examples of the organic salt particles include terephthalate such as calcium oxalate, calcium, barium, zinc, manganese, and magnesium.

  Examples of the crosslinked polymer particles include homopolymers or copolymers of vinyl monomers such as divinylbenzene, styrene, acrylic acid or methacrylic acid. In addition, organic particles such as polytetrafluoroethylene, benzoguanamine resin, thermosetting urea resin, and thermosetting phenol resin may be used.

  Examples of the method for adding the lubricant include a method in which the lubricant is dispersed in the polymerization step of the polyester used as the film raw material, a method in which the polyester after polymerization is melted again, and the like. In addition, when trying to impart slipperiness to the film, there is a method of roughening the surface with the above-mentioned lubricant particles and reducing the contact area. However, if too much is added, the transparency of the film is lowered and the commercial value is impaired. Therefore, it is recommended to reduce the lubricant particles or not to use them, and to form a slippery layer described later to impart slipperiness to the film.

  Furthermore, in the present invention, it is preferable that one side and the other side of the film can be solvent-bonded. The solvent adhesiveness can be ensured by the above-described film composition and the layer constitution, the film forming method, the coating layer composition, the coating method and the like described later. In the present invention, being capable of solvent bonding means that the solvent bonding strength is 3 N / 15 mm or more in the evaluation method of the examples.

  Further, in the present invention, when the film was stored for 2 weeks in an environment of a temperature of 30 ° C. and a relative humidity of 85%, a tensile test was performed in a direction perpendicular to the maximum shrinkage direction of the stored film in accordance with JIS K7127. The percentage with respect to the total number of test pieces (20 pieces) with respect to the number of test pieces having an elongation of 5% or less is preferably 10% or less. The percentage of the total number of test pieces (20 pieces) with respect to the number of test pieces having an elongation of 5% or less is more preferably 5% or less, and further preferably 0%. By setting it as the said characteristic range, processing stability which does not generate | occur | produce defects, such as a fracture | rupture at the time of a process, can be obtained even after storing a film for a long period of time. The above-mentioned characteristic range can be obtained by the above-described film composition, the layer configuration described later, the film forming method, and the like.

  Furthermore, in the present invention, it is preferable that the yield point stress value in the tensile stress-strain curve when the tensile test is performed in the direction orthogonal to the maximum shrinkage direction of the film is 5.0 MPa or more according to JIS K7127. By setting the yield point stress value to 5.0 MPa or more, adhesion to the container can be obtained when the yield point stress value is attached to the container or the like. The yield point stress value is more preferably 5.5 MPa or more, and even more preferably 6.0 MPa or more.

  Furthermore, in this invention, the layer which consists of a polyester resin whose ethylene terephthalate unit is less than 72 mol% in all the polyester resin components, and the layer which consists of a polyester resin whose ethylene terephthalate unit is 72 mol% or more in all the polyester resin components It is preferable that it is the laminated structure which has these. More preferably, it has a layer (B) made of a polyester resin in which the ethylene terephthalate unit derived from polyethylene terephthalate is 40 mol% or more in all polyester resin components, and one outermost layer contains all polyester resin components A layer (A) comprising a polyester resin having an ethylene terephthalate unit derived from polyethylene terephthalate of less than 40 mol%, and the other outermost layer comprising a polyester resin having a polyethylene terephthalate content of less than 40% by weight in all polyester resin components It is a heat-shrinkable polyester film which has the below-mentioned easy-sliding layer adjacent to (A).

  The ethylene terephthalate unit in the layer (B) is more preferably at least 74 mol%, more preferably at least 76 mol%, more preferably at least 50 mol%, more preferably at least 55 mol as an ethylene terephthalate unit derived from polyethylene terephthalate. % Or more.

  More preferably, the ethylene terephthalate unit in the layer (A) is 71 mol% or less, more preferably 70 mol% or less, and more preferably 38 mol% or less, more preferably 36 mol as an ethylene terephthalate unit derived from polyethylene terephthalate. % Or less.

  By adopting the above film structure, the film can be toughened, hardly broken, the yield point stress can be increased, and solvent adhesion can be ensured.

  More preferably, the polyester resin mixture (B ′) in which polyethylene terephthalate is 40% by weight or more in the total polyester resin component and the polyester resin mixture (A ′ in which polyethylene terephthalate is less than 40% by weight in the total polyester resin component) ) Is melted and co-extruded using two extruders, so that (A) is an outer layer and (B) is an inner layer, and two types and three layers of unstretched polyester film or uniaxially stretched polyester system After obtaining a film and applying a coating solution containing an easy-to-slip component to be described later on at least one surface, the coated film is further biaxially stretched or uniaxially stretched and wound to wind the heat-shrinkable polyester film of the present invention. A roll can be obtained.

  Next, the film surface treatment will be described. During film formation or after film formation, one or both surfaces of the film surface is subjected to corona treatment, flame treatment, plasma treatment, ultraviolet treatment, etc. in an air atmosphere to improve adhesion to various inks. ing. Among industrial operations, corona treatment under an air atmosphere is most widely performed as a surface treatment. When the heat-shrinkable polyester film is also subjected to corona treatment, the surface wetting tension is increased and the adhesion to various types of ink is improved, as with other films. However, when corona treatment is performed, fusion or blocking is likely to occur when label-cutting a heat-shrinkable polyester film.

  In order to satisfy the requirement (2), it is preferable to form the slippery layer as the outermost layer of the film. In order to form an easy-sliding layer, a method of film-coating a coating solution for forming an easy-sliding layer is the simplest.

  It should be noted that the use of a particulate lubricant component as a lubricant may interfere with the transparency of the film and may cause the particles to agglomerate. Preferred lubricants that do not cause such problems include paraffin wax, microwax, polypropylene wax, polyethylene wax, ethylene-acrylic wax, stearic acid, behenic acid, 12-hydroxystearic acid, stearic acid amide, oleic acid amide, Erucic acid amide, methylene bis stearic acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide, butyl stearate, monoglyceride stearate, pentaerythritol tetrastearate, hydrogenated castor oil, stearyl stearate, siloxane, higher alcohol type Molecule, stearyl alcohol, calcium stearate, zinc stearate, magnesium stearate, lead stearate, silicone (dimethylsiloxa ) Based low molecular weight compound (oil) or silicone (dimethylsiloxane) -based resins., These other which may be used alone, or may be used in combination of two or more if necessary. Of these, silicone compounds are recommended. This is because the dynamic friction coefficient of the film surface is reduced, the change of the friction coefficient before and after the hot water treatment is small, and the solvent adhesiveness of the film is hardly hindered.

  In addition, silicone-based compounds often used as release agents have low surface energy, low adhesion to the substrate, and low toughness as a film. Therefore, when wound up as a roll, the reverse of the coated surface. Part of the silicone compound of the easy-sliding layer is transferred to the surface, and has an effect of maintaining good opening properties during the tubing process.

  The content of the silicone component is preferably 10 to 100% by weight, more preferably 50 to 100%, as the abundance in the slippery layer. If the content is less than 10% by weight, the effect of improving slipperiness is small.

  Here, the silicone type refers to organosiloxanes, which are oily, rubbery, and resinous, and are called silicone oil, silicone rubber, and silicone resin, respectively. Since these all have a water repellent effect, a lubrication effect, a release action, etc., inclusion in the outermost layer portion of the film is effective in reducing the surface friction. In addition, when used as a beverage container label, it is often attached by heat-shrinking using steam or hot air. In a slippery layer with low water resistance, the heat-shrinking treatment using steam causes a decrease in slipperiness. Although it is easy, good slipperiness can be maintained even after the steam treatment due to the water repellent effect inherent in silicone.

Further, the easy slip layer component may contain a resin component.
Examples of the resin component include polyester resins, polyamide resins, polyurethane resins, epoxy resins, phenol resins, acrylic resins, polyvinyl acetate resins, polyolefin resins such as polyethylene and polypropylene, and copolymers thereof. Or a modified resin, a cellulose resin, etc. are mentioned. When the amount of the binder added increases, the slipperiness decreases, and the adhesion and toughness of the film increase, making it difficult for transfer to occur when the film is rolled up, and the effect of improving the opening property is reduced. Therefore, attention is necessary.

  It is preferable to use water-soluble or water-dispersible lubricants and binder resin components from the viewpoints of safety and environmental friendliness.

The amount of the coating solution, the amount present on the film after stretching is preferably 0.002~0.5g / ^{m 2,} more preferably from 0.005~0.4g / ^{m 2.} If it is less than 0.002 g / m ² , the effect of improving slipperiness and openability becomes small, and if it exceeds 0.5 g / m ² , the transparency of the film is lowered and the solvent adhesiveness is also lowered. This is not preferable because wear debris is likely to be generated during processing, leading to a decrease in productivity.

  As the in-line coating method, the fountain die coating / smoothing bar method is recommended in order to obtain the above coating amount uniformly and accurately. In order to satisfy the requirements of the present invention, the die lip gap is preferably in the range of 100 to 600 μm, and the nozzle gap is preferably in the range of 100 to 400 μm. It is preferable to use a smoothing bar that is of a rotary type and that has a fluctuation degree of fluctuation in rotational peripheral speed within ± 1%.

  In addition, in order to obtain a uniform coating amount in the longitudinal (longitudinal) direction of the film, it is applied in the form of a film having stable film properties in the length direction and the width direction as described above, and the coating property of the coating liquid. It is preferable to suppress fluctuations. For this purpose, it is effective to keep the fluctuation range of the surface energy of the coating liquid as small as possible.

  In the fountain die coating / smoothing bar method, the coating solution is supplied from the fountain die to the film. Next, an excess coating solution is scraped off using a smoothing bar so as to obtain a uniform coating amount. It is advantageous in terms of cost that the liquid scraped off at this time is returned to the tank and used again as a coating liquid. However, once it is supplied from the fountain die and scraped off, some of the easily volatile components volatilize, and the entire liquid composition often changes over time. Along with this, the surface energy of the liquid changes, which may lead to changes in coating properties and surface physical properties of the film.

In order to suppress the liquid composition fluctuation, a method of continuously adding volatilizing components and amounts is recommended.
However, when adding a volatile component, especially when using a water-dispersible resin or the like, care should be taken because the dispersion state of the liquid is often made unstable by the addition method. A method of suppressing the deterioration of dispersibility by a method of adding after diluting the component to be added or adding a droplet in a small size is preferable.

  A specific example of producing a polyester film will be described. First, the raw material chips controlled to a size satisfying the means (i) are dried using a dryer such as a hopper dryer or paddle dryer, or a vacuum dryer, and extruded into a film at a temperature of 200 to 300 ° C. . Alternatively, an undried polyester raw material is similarly extruded into a film while removing moisture in a vented extruder. After extrusion, it is cooled with a casting roll (rapid cooling) to obtain an unstretched film. The “unstretched film” includes a film on which a tension necessary for film feeding is applied.

  The unstretched film is stretched. The stretching treatment may be performed continuously after cooling with a steam casting roll or the like, or may be wound after being cooled into a roll and then performed.

  In order to achieve the object of the present invention, it is practical in terms of production efficiency that the maximum shrinking direction is the film transverse (width) direction. Hereinafter, an example of a centrifugal method in which the main shrinking direction is the transverse direction will be described. Indicates. Even when the maximum shrinkage direction is the longitudinal (longitudinal) direction of the film, the film can be stretched according to ordinary operations such as changing the stretching direction by 90 ° in the following method.

  The heat shrink characteristics of a long film may vary due to process fluctuations when the film is stretched in addition to the film composition fluctuations described above. Reducing fluctuations in the heat shrinkage behavior of the long film is preferable because it leads to a reduction in the defective rate of products. In order to reduce the fluctuation of the heat shrinkage behavior, it is preferable to suppress the fluctuation of the temperature in the step of stretching the film and reduce the fluctuation range of the surface temperature of the film as much as possible.

  In the case of a polyester film, when it is uniaxially stretched in the transverse direction using a tenter, there are a preheating step before stretching, a stretching step, a heat treatment step after stretching, a relaxation treatment, a maximum stretching treatment step, and the like. In particular, in the preheating process, the stretching process, and the heat treatment process after stretching, the fluctuation range of the surface temperature of the film measured at an arbitrary point is controlled within an average temperature of ± 1 ° C. Is a preferred means for. More preferably, the average temperature is within ± 0.5 ° C.

  Temperature fluctuations in the preheating step, the drawing step, and the heat treatment step after drawing greatly influence the fluctuations in the heat shrinkage rate (maximum shrinkage direction and orthogonal direction) and the maximum heat shrinkage stress value. Therefore, when the fluctuation range of the surface temperature of the film in these steps is small, the film is stretched or heat-treated at the same temperature over the entire length of the film, and the heat shrinkage behavior becomes uniform. Of course, it is preferable that the fluctuation range of the surface temperature of the film is small also in the relaxation treatment and the maximum stretching treatment step.

In order to reduce the fluctuation of the film surface temperature, for example, a wind speed fluctuation suppression facility equipped with an inverter so that the wind speed of the hot air heating the film can be controlled, or a low pressure of 500 kPa or less (5 kgf / cm ² or less) is used as the heat source. It is preferable to use equipment that can suppress temperature fluctuations of hot air using steam.

  The fluctuation range of the film surface temperature measured at an arbitrary point is, for example, the film surface temperature continuously during film production, for example, an infrared non-contact surface thermometer, after 2 m has passed since the drawing process. This is the range of fluctuation when measured by. Since the average temperature can be calculated when film production for one roll is completed, if the fluctuation range of the film surface temperature is within the average temperature ± 1 ° C., the film is stretched under the same conditions over the entire length of the steady region of the film. Therefore, the fluctuation of the heat shrinkage behavior is also reduced.

Moreover, when paying attention to uniforming the thickness distribution of the target heat-shrinkable polyester film, it is preferable to perform a preheating step prior to the stretching step when stretching in the transverse direction using a tenter or the like, In this preheating step, heating is performed at a low wind speed so that the thermal conductivity coefficient is 0.0013 calories / cm ² · sec · ° C. or less until the film surface temperature is within a range of Tg + 0 ° C. to Tg + 60 ° C. It is preferable to carry out.

  Stretching in the transverse direction is performed at a predetermined temperature within a range of Tg-20 ° C to Tg + 40 ° C, and is stretched 2.3 to 7.3 times, preferably 2.5 to 6.0 times. Thereafter, heat treatment is performed at a predetermined temperature in the range of 60 ° C. to 110 ° C. with 0-15% elongation or 0-15% relaxation, and as necessary at a predetermined temperature in the range of 40 ° C. to 100 ° C. Further heat treatment is performed to obtain a heat-shrinkable polyester film. In this transverse stretching step, it is preferable to use equipment capable of reducing the fluctuation of the film surface temperature as described above.

  As a stretching method, not only transverse uniaxial stretching with a tenter, but also stretching in the longitudinal direction by 1.0 to 4.0 times, preferably 1.1 to 2.0 times may be performed. When biaxial stretching is performed in this manner, either sequential biaxial stretching or simultaneous biaxial stretching may be performed, and restretching may be performed as necessary. Further, in the sequential biaxial stretching, any of stretching methods such as vertical and horizontal, horizontal and vertical, vertical and horizontal and horizontal and vertical and horizontal directions may be used. Even when these longitudinal stretching steps or biaxial stretching steps are employed, it is preferable to minimize the fluctuation of the film surface temperature as much as possible in the preheating step, the stretching step and the like, similarly to the transverse stretching.

From the viewpoint of suppressing the internal heat generation of the film accompanying stretching and reducing the film temperature unevenness in the width direction, the heat transfer coefficient of the stretching process is preferably 0.0009 calories / cm ² · sec · ° C. or more. . 0.0013 to 0.0020 calories / cm ² · sec · ° C. is more preferable.

  The heat-shrinkable polyester film roll in the present invention is preferably a roll obtained by winding a heat-shrinkable polyester film having a width of 0.2 m or more around a winding core (core) with a length of 300 m or more. A roll of a film having a width of less than 0.2 m has a low industrial utility value, and a film roll having a width of less than 300 m has a small film winding length, and thus covers the entire length of the film. Since the change in slipperiness and heat shrinkage behavior is reduced, the effect of the present invention is hardly exhibited. The width of the heat-shrinkable polyester film roll is more preferably 0.3 m or more, and further preferably 0.4 m or more. The length of the heat-shrinkable polyester film wound around the roll is more preferably 400 m or more, and further preferably 500 m or more.

  The upper limit of the width and the winding length of the film roll is not particularly limited, but from the viewpoint of ease of handling, the width is generally 1.5 m or less, and the winding length is preferably 6000 m or less when the film thickness is 45 μm. As the winding core, a plastic core such as 3 inch, 6 inch, or 8 inch, a metal core, or a paper tube can be usually used.

  The thickness of the film constituting the heat-shrinkable polyester film roll of the present invention is not particularly limited. For example, as the heat-shrinkable polyester film for labels, 10 to 200 μm is preferable, and 20 to 100 μm is more preferable. preferable.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are not intended to limit the present invention, and modifications and implementations within the scope of the present invention are included in the present invention. In addition, the measuring method of the physical property of the film obtained by the Example and the comparative example is as follows.

(1) Confirmation of steady region and setting of sample cut-out portion From the second end portion (winding end portion) of the film about a film roll wound with a film having a length of 1000 m obtained in Examples and Comparative Examples described later. Samples of 5 points were cut out at intervals of 20 m, and samples of 5 points were cut out at intervals of 20 m from the inner part of the film from the first end (winding start part) of the film toward the first end, and the maximum shrinkage direction of these samples The thermal contraction rate (described later) of was measured. The variation of the heat shrinkage rate of each sample was within 20%. Moreover, the production / stretching process was stable during the production of the film. Therefore, it was confirmed that each film roll corresponds to the steady region over the entire length of the film.

(2) Thermal contraction rate in the maximum shrinkage direction The film is cut into a 10 cm × 10 cm square along the longitudinal direction and its orthogonal direction, and treated in warm water at 95 ° C. ± 0.5 ° C. for 10 seconds under no load condition. After heat shrinking, the sample was immediately immersed in water at 25 ° C. ± 0.5 ° C. for 10 seconds, and then the length of the sample in the vertical and horizontal directions was measured and determined according to the following formula. The direction with the largest shrinkage rate was defined as the maximum shrinkage direction.
Heat shrinkage rate (%) = 100 × (length before shrinkage−length after shrinkage) ÷ (length before shrinkage)

(3) Friction coefficient The dynamic friction coefficient μd between film surfaces was measured in an environment of 23 ° C. and 65% RH in accordance with JIS K-7125.

(4) Yield point stress Using TENSILON / UTM-IIIL (TOYO MEASURING INSTRUMENTS CO. LTD), in the direction perpendicular to the main stretching direction (main shrinkage direction) of the film, the ambient temperature is 23 ° C., the gap between the chucks is 100 mm, and the width A 15 mm film test piece was subjected to a tensile test at a tensile speed of 200 mm / min, and a tensile stress-distortion curve was created. Yield point stress (unit: MPa) The initial maximum point portion of the tensile stress-distortion curve was used.

(5) The film is stored for 2 weeks in an environment with a tear resistance temperature of 30 ° C. and a relative humidity of 85%. According to JISK 7127, a tensile test is performed in a direction orthogonal to the maximum shrinkage direction of the film after storage. The number of test pieces was 20. The test piece length was 200 mm, the distance between chucks was 100 mm, the test piece width was 15 mm, the temperature was 23 ° C., and the tensile speed was 200 mm / min. The number of test pieces that broke at an elongation of 5% or less was counted, and the percentage with respect to the total number of test pieces (20 pieces) was determined to determine the tear resistance (%).

(6) Solvent bond strength 1,3-dioxolane was applied to one surface of the film with a cotton swab in an application amount (5 ± 0.3) g / m ² and an application width of 5 ± 1 mm, and the other surface was applied to this surface. A seal was applied by pressing and bonding. Cut the seal part to a width of 15 mm in the direction perpendicular to the flow direction at the time of the label tubing process, and set it on a universal tension tester STM-50 manufactured by Baldwin Co., Ltd. according to JIS K 6854. Measurement was performed at a pulling speed of 200 mm / min.

(7) Openability after label cutting Slit the heat-shrinkable film, then use a center seal machine to make a tube by solvent-bonding with 1,3-dioxolane so that the easy-slip layer coating surface is on the outside, It wound up in a two-fold state. Subsequently, the tube was left for 24 hours in a room controlled at 25 ± 1 ° C. and RH65 ± 2%. Thereafter, the tube was continuously cut with a cutting machine under the same indoor atmosphere conditions (number of cut labels: 200) to produce a heat shrinkable film label. All the labels were opened by hand, and the opening of the cut portion was determined according to the following criteria (full score of 3).
3: Opening without resistance 2: Opening is possible but light resistance exists 1: Cutting part cannot be opened

Film 1
1) Polyester resin and unstretched film (1) Polyester resin and unstretched film Polyethylene terephthalate 20% by weight, terephthalic acid 100% by mole, neopentyl glycol 30% by mole, and ethylene glycol 70% by weight , And a polyester composition mixed with 10% by weight of polybutylene terephthalate, separately fed separately to the hopper directly above the extruder with a metering screw feeder, and mixed in the hopper (A). Also, 60% by weight of polyethylene terephthalate, Extruders were prepared by mixing 30% by weight of polyester composed of 100% by mole of terephthalic acid, 30% by mole of neopentyl glycol and 70% by mole of ethylene glycol, and 10% by weight of polybutylene terephthalate. Separately fed separately to the hopper directly above with a fixed screw feeder, mixed in the hopper (B), melt extruded at 280 ° C, and (A) becomes the outer layer and (B) becomes the inner layer by multi-manifold die method , Laminated at a ratio of thickness 1: 2: 1, extruded as 2 layers and 3 layers, and rapidly cooled and solidified with a chill roll to obtain an unstretched laminated film having a thickness of 180 μm. At this time, the capacity of the hopper was 150 kg in terms of the raw material weight, and the extrusion amount of the extruder was 450 kg per hour as a whole.

(Preparation of coating solution)
Solid content of aqueous dispersion of silicone (SH7024 manufactured by Toray Dow Corning Silicone Co., Ltd.) is 70% by mass in the total solid content of the coating liquid, and solid content of aqueous dispersion of copolyester resin (AGN709 manufactured by Toyobo) is solid. 100% of an aqueous solution containing 20% by mass of acetylene glycol derivative (Surfinol 485 manufactured by Air Products Japan) in a solid content of 10% by mass and 20% by mass of isopropyl alcohol was prepared and put into a tank. The liquid temperature in the tank was kept at 25 ° C. ± 5 ° C.

  A coating solution is applied to the unstretched film by a fountain die coat / smoothing bar method, a die lip gap of 320 μm, a nozzle gap of 200 μm, a smoothing bar having a diameter of 8 mm and a rotation speed of 110 ± 1 (rotation / min), and a speed of 20 kg / min. Then, the coating solution was supplied. In the tank, a mixed solution of water / isopropyl alcohol = 70/30 was continuously added in an amount of 80 g / min.

Subsequently, the coating film was pre-heated at 100 ° C. for 10 seconds with a tenter, then stretched 4.0 times in the transverse direction at 80 ° C., and heat-treated at 80 ° C. for 10 seconds, continuously having a thickness of 45 μm and a coating amount of 0 A heat-shrinkable polyester film having a thickness of 0.01 g / m ² was formed. The temperature fluctuation of the film surface when the film is continuously formed 1000 m is the average temperature ± 0.7 ° C. in the preheating step, the average temperature ± 0.5 ° C. in the stretching step, and the average temperature ± 0.5 ° C. in the heat treatment step. It was in the range.

Subsequently, the corona treatment was performed on the surface opposite to the surface on which the easy-slip layer was formed under the following conditions. The corona-treated electrode was a bar electrode made of aluminum, and the treatment roll was made of silicone rubber. The gap between the processing electrode and the film was 0.5 mm. The high-frequency power supply device used was a device from Kasuga Electric Co., Ltd., and the surface treatment energy value was 0.01 kW / m ² / min, and the treatment atmosphere temperature and the treatment roll surface temperature were both 55 ° C. to perform corona treatment. The film surface temperature during the treatment was 55 ° C.
In addition, the energy conversion value per film area at the time of surface treatment is the energy conversion value per film area of surface treatment (kW / m ² / min)
= High-frequency power device current value (A) x voltage (kV) ÷ electrode width (m) ÷ film travel speed (m / min)
As sought.

  The obtained film was slit to a width of 0.5 m and a length of 1000 m, adjusted so that the repulsion number (Ra) with an LR type Schmitt test hammer was 50 to 60 in the state of a rolled-up roll, and 3 inch paper The film was wound around a tube to obtain a heat-shrinkable film roll. The obtained film roll is film 1, and the film physical properties are shown in Tables 1 and 2.

Film 2
About coating solution Solid content of dimethyl silicone resin (SE4005 manufactured by Nissin Chemical Laboratory) is 90% by mass in total solid content of coating solution, and solid content of acetylene glycol derivative (Surfinol 485 manufactured by Shin-Etsu Chemical Co., Ltd.) is solid content. A heat-shrinkable film roll was obtained by the same method as in Example 1 except that the aqueous liquid contained 10% by mass and isopropanol 20% by mass. The obtained film roll was used as film 2 and the film physical properties are shown in Tables 1 and 2.

Film 3
In each of the polyester compositions (A) and (B), 60% by weight of polyethylene terephthalate, 30% by weight of polyester comprising 100% by mole of terephthalic acid, 30% by mole of neopentyl glycol and 70% by mole of ethylene glycol, and 10% by weight of polybutylene terephthalate % Heat-shrinkable film rolls were obtained in the same manner as in Example 1 except that the percentages were mixed.
The obtained film roll was used as film 3, and the film physical properties are shown in Tables 1 and 2.

Film 4
In each of the polyester compositions (A) and (B), 20% by weight of polyethylene terephthalate, 70% by weight of polyester comprising 100% by mole of terephthalic acid, 30% by mole of neopentyl glycol and 70% by mole of ethylene glycol, and 10% by weight of polybutylene terephthalate % Heat-shrinkable film rolls were obtained in the same manner as film 1, except that the percentages were mixed.
The obtained film roll is taken as film 4 and the film physical properties are shown in Tables 1 and 2.

Film 5
About the polyester composition, a mixture of 60% by weight of polyethylene terephthalate, 30% by weight of polyester composed of 100% by mole of terephthalic acid, 30% by mole of neopentyl glycol and 70% by mole of ethylene glycol, and 10% by weight of polybutylene terephthalate ( A), a mixture of 20% by weight of polyethylene terephthalate, 70% by weight of polyester composed of 100% by mole of terephthalic acid, 30% by mole of neopentyl glycol and 70% by mole of ethylene glycol, and 10% by weight of polybutylene terephthalate (B And a heat-shrinkable film roll was obtained in the same manner as film 2, except that the coating amount was 0.001 g / m ² .
The obtained film roll was used as film 5 and the film physical properties are shown in Tables 1 and 2.

Film 6
A heat-shrinkable film roll was obtained in the same manner except that the coating amount in the film 2 was 0.001 g / m ² .
The obtained film roll was used as film 6 and the film physical properties are shown in Tables 1 and 2.

Film 7
A heat-shrinkable film roll was obtained in the same manner except that the coating solution was not applied to film 1.
The obtained film roll is taken as film 7 and the film physical properties are shown in Tables 1 and 2.

Cylindrical labels were prepared with films 1 to 7 such that a coat layer having a height of 180 mm and a circumference of 220 mm was the outer surface.
Using a steam tunnel made by Fuji Astec Inc (model: SH-1500-L), the above label was passed through for 15 seconds, at a first zone temperature of 70 ° C., a second zone temperature of 75 ° C., and a third zone temperature of 82 ° C., and 500 ml It was heat-shrinked and attached to a PET bottle beverage. In film 3, due to insufficient shrinkage, the label did not adhere to the container, and in film 5, the adhesive part was peeled off and the tubular shape could not be maintained. Other labels were kept in a cylindrical shape.

  When loaded into a vending machine, there was no clogging of 400 films 1, 2, and 4; film 6 clogged 4 out of 400; Example 7 clogged 8 out of 400 did.

  When the heat-shrinkable film roll of the present invention is used as a label for a beverage container by heat-shrinking treatment, friction between containers can be kept low, and it is generated due to slippage in the film roll and variations in surface characteristics. It is possible to prevent the occurrence of defects due to clogging or the like in the vending machine. In addition, the film is excellent in film formability, toughness as a label, and processability, and is useful in industrial production.

Claims (11)

A film roll formed by winding a heat-shrinkable polyester film, the heat-shrinkable polyester film satisfying the following requirements (1) to (3): .
When the end of the film in the steady region where the film properties are stable in the length direction of the film is the first end and the end of the end of the film is the second end, the second end A first sample cutout is provided within 2 m inside the part, a final cutout is provided within 2 m inside the first end, and a sample cutout is provided approximately every 100 m from the first sample cutout. Each sample cut into a 10 cm × 10 cm square shape is immersed in warm water at 95 ° C. for 10 seconds and then pulled up and then immersed in water at 25 ° C. for 10 seconds. , 50% or more for all samples.
-About each sample cut out separately from each sample cut-out part described in said (1), the dynamic friction coefficient of the 1st surfaces of the sample cut out when both surfaces of a film are made into the 1st surface and the 2nd surface, respectively (Μd) is 0.28 or less in all samples, and the dynamic friction coefficient (μd) between the second surfaces is 0.35 or less in all samples.
-Ethylene terephthalate is the main component of the polyester resin component constituting the film, and the ethylene terephthalate unit is 70 mol% or more.   The heat-shrinkable polyester film roll according to claim 1, wherein the film is capable of solvent bonding.   When the film is stored for 2 weeks in an environment of a temperature of 30 ° C. and a relative humidity of 85%, the elongation is 5% or less when a tensile test is performed in a direction perpendicular to the maximum shrinkage direction of the film after storage in accordance with JIS K7127. 3. The heat-shrinkable polyester film roll according to claim 1, wherein the percentage of the total number of test pieces (20 pieces) with respect to the number of test pieces is 10% or less in all samples.   According to JIS K7127, the yield stress value in the tensile stress-strain curve when the tensile test is performed in the direction orthogonal to the maximum shrinkage direction of the film is 5.0 MPa or more in all samples. The heat-shrinkable polyester film roll according to any one of?     About each sample which has the layer which consists of a polyester resin whose ethylene terephthalate unit is less than 72 mol% in all the polyester resin components, and was cut out separately from each sample cut-out part described in (1) of Claim 1 The kinetic friction coefficient (μd) between the first surfaces of the cut sample is 0.28 or less for all the samples, and the same friction coefficient (μd) between the second surfaces is 0.35 or less for all the samples. The heat-shrinkable polyester film roll according to any one of claims 1 to 4.   The heat-shrinkable polyester film roll according to claim 5, wherein the heat-shrinkable polyester film roll has a layer made of a polyester resin in which ethylene terephthalate units derived from polyethylene terephthalate are less than 40 mol% in all polyester resin components.   The heat-shrinkable polyester film roll according to claim 5 or 6, comprising a layer made of a polyester resin having an ethylene terephthalate unit of 72 mol% or more in all polyester resin components.   The heat-shrinkable polyester film roll according to claim 7, further comprising a layer made of a polyester resin in which ethylene terephthalate units derived from polyethylene terephthalate are 40 mol% or more in all polyester resin components. The silicone component is contained in the outermost layer on the first surface side of the film, and the amount of the silicone component-containing layer is 0.002 to 0.5 g / m ^2. The heat-shrinkable polyester film roll described.   A layer (A) made of a polyester resin having an ethylene terephthalate unit of less than 72 mol% in all polyester resin components, and a layer (B) made of a polyester resin having an ethylene terephthalate unit of 72 mol% or more in all polyester resin components The heat-shrinkable polyester film roll according to any one of claims 1 to 9, wherein the heat-shrinkable polyester film roll is located on both outer layer sides.   One outermost layer has a layer (A) made of a polyester resin having less than 72 mol% of ethylene terephthalate units in all polyester resin components, and the other outermost layer has ethylene terephthalate units in all polyester resin components. The heat-shrinkable polyester film roll according to any one of claims 1 to 10, further comprising a silicone component-containing layer adjacent to the layer (A) composed of 72 mol% or more of a polyester resin.