JP2006199908A - Heat-shrinkable polyester film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-shrinkable polyester film suitable for label uses, causing no heat-resistance degradation, having excellent shrinkage characteristics at low temperatures, excellent in shrinkage finish properties, extremely slightly causing shrinkage whitening even when the film is preserved for a long term, having excellent tear resistance, and excellent in productivity and quality. <P>SOLUTION: The heat-shrinkable polyester film contains 0.01-1 wt.% heat stabilizer and is as follows. The heat shrinkage percentage of a sample in the maximum shrinkage direction is ≥40% when the sample cut out into a square form of 10 cm×10 cm is dipped in hot water at 98°C for 10 s, pulled up, dipped in water at 25°C for 10 s and then pulled up, the difference between the haze of the film when the heat-shrinkable polyester film is preserved under the environment at 30°C temperature and 85% relative humidity for 4 weeks and the film after the preservation is subjected to heat shrinkage under prescribed conditions and the haze of the film before the heat shrinking treatment is ≤5%, and molten specific resistance value is ≤0.70×10<SP>8</SP>Ωcm at 275°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat-shrinkable polyester film, and more particularly to a heat-shrinkable polyester film suitable for label applications.

Heat-shrinkable plastic films are widely used for applications such as shrink wrapping, shrinkage labels, cap seals, etc. by utilizing the property of shrinking by heating. Among them, stretched films such as polyvinyl chloride films, polystyrene films, and polyester films are used for labels, cap seals, and integrated packaging in various containers such as polyethylene terephthalate (PET) containers, polyethylene containers, and glass containers. Has been.

  However, the polyvinyl chloride film has problems such as low heat resistance, generation of hydrogen chloride gas during incineration, and dioxin. Further, when a heat-shrinkable vinyl chloride resin film is used as a shrink label for a PET container or the like, there is a problem in 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, heat-shrinkable films have recently been used in hot beverage PET bottle labels, but when stored in warming equipment such as hot-warmers, the heat-shrinkable polystyrene film comes into contact with hot wires that have become hot. There is a problem that the shrinkage label melts instantly. Furthermore, the polystyrene resin needs to be incinerated at a high temperature and has a problem that a large amount of black smoke and off-flavor are generated during incineration.

  Polyester films without these problems (excellent in solvent resistance, heat resistance, and environmental suitability) are highly expected as shrink labels to replace polyvinyl chloride films and polystyrene films. Along with the increase, the usage amount is also increasing.

  However, the conventional heat-shrinkable polyester film has also been required to have further improvement in shrinkage characteristics. In particular, when compared with heat-shrinkable polystyrene film, shrinkage spots and wrinkles occur during shrinkage, and characters and designs printed before shrinkage are coated and attached to containers such as PET bottles, polyethylene bottles, glass bottles, There has been a demand from the user side that it may be distorted after contraction and it is desired to reduce this distortion as much as possible. In addition, the polyester film may be inferior in shrinkability at a low temperature, and in order to obtain a necessary shrinkage amount, it has to be shrunk at a high temperature, and the bottle body may be deformed or whitened.

  By the way, when using a heat-shrinkable film for coating a real container, after performing a printing process as necessary, it is processed into a form such as a label (tubular label) or a tube, and these processed films The inside of a shrinking tunnel (steam tunnel) that heats and shrinks by blowing steam on the container, or a shrinking tunnel (hot air tunnel) that heats and shrinks by blowing hot air is placed on a belt conveyor, etc. It is allowed to pass through and is heat-shrinked so as to be closely attached to the container.

  When using a hot-air tunnel in which heat-shrinkable polyester films tend to cause temperature spots during heat shrinkage, the polyester-based films are likely to cause shrinkage whitening, shrinkage spots, wrinkles, distortion, and the like.

  In addition, steam tunnels have better heat transfer efficiency than hot air tunnels and can be heated and shrunk more uniformly, and can provide a better shrink finish appearance than hot air tunnels. The film has a problem that the shrinkage finish after passing through the steam tunnel is not so good as compared with the polyvinyl chloride film and the polystyrene film.

  Furthermore, the heat-shrinkable film is required to increase productivity in addition to the shrinkage finish, and from the viewpoint of quality, it is also required to have high transparency and a uniform film thickness. In order to increase productivity, it is conceivable that when a melt-extruded film is cooled by a casting roll, the film and the roll are electrostatically brought into close contact with each other to increase the cooling efficiency and increase the casting speed. If the film is electrostatically adhered to the roll with a strong adhesion force, defects on the film surface (such as occurrence of pinner bubbles) can be reduced, and further, the thickness of the film can be made uniform. In order to bring the film into electrostatic contact with the roll, it is important how many charge carriers are present on the surface of the molten film immediately after extrusion before contacting the roll. In order to increase the number of charge carriers, it is effective to lower the specific resistance by modifying the polyester.

As disclosed in Patent Document 1, a polyester obtained by copolymerization of 1,4-cyclohexanedimethanol is attracting attention because of its excellent transparency and brightness. However, since this copolyester has a high specific resistance value, it is necessary to improve electrostatic adhesion from the viewpoint of improving the productivity and quality of the film.
JP 2000-504770 Gazette

Patent Document 2 includes 10 to 50 mol% of 1,4-cyclohexanedimethanol component in 100% of a polyhydric alcohol component, and the mass ratio of alkaline earth metal atom M ² and phosphorus atom in the film (M ² / P) is 1.2 to 5.0, the content of alkaline earth metal atoms M ^{2 in} the film is 40 to 400 ppm (mass basis), and the content of phosphorus atoms is 60 to 600 ppm. By adding (mass basis), the melt specific resistance of the polyester copolymerized with 1,4-cyclohexanedimethanol (CHDM) is lowered, and the electrostatic adhesion is improved.
JP 2003-41026 A

  However, polyesters copolymerized with 1,4-cyclohexanedimethanol differ greatly in thermal properties (melting point, crystallinity, glass transition temperature, etc.) compared to PET, and 1,4-cyclohexanedimethanol has a molecular skeleton. It has hydrogen bonded to tertiary carbon, and is susceptible to thermal oxidative degradation reaction and has low heat resistance. For this reason, in the polyester copolymerized with 1,4-cyclohexanedimethanol, if an additive is added to lower the melt specific resistance value, the thermal properties are greatly changed, the heat resistance is further lowered, and the polyester is colored. , Viscosity decrease (molecular weight decrease) is likely to occur. In addition, poor operability (generation of lip streaks, contamination with oligomers, etc.) is likely to occur due to a decrease in heat resistance. The lip streaks, when extruded from the extruder, melted resin gelled or deteriorated material adheres to the lip portion of the die and accumulates over time, resulting in streaks on the molten resin. When the lip streaks are generated, the production is stopped and the lip cleaning is not performed until the lip streaks are generated, so that the productivity is lowered. In JP-A-2003-41026, unlike other additives, alkaline earth metal compounds, phosphorus compounds, alkali metal compounds, etc. have the heat resistance of polyester copolymerized with 1,4-cyclohexanedimethanol. It is said that the productivity and quality of the polyester film can be increased by lowering the melt specific resistance value without lowering the heat resistance without unexpectedly lowering the heat resistance, but when the industrial production is the subject of the present invention In continuous film formation for a long time, improvement in poor operability such as lip streaks cannot be achieved.

  The present invention has been made paying attention to the circumstances as described above, and its purpose is to have excellent shrinkage characteristics at low temperature without lowering heat resistance, excellent shrinkage finish, and longer time. A heat-shrinkable polyester film suitable for labeling applications that has extremely low shrinkage whitening, excellent tear resistance, and excellent productivity (reduction of lip streaks) and quality even when the film is stored. The issue is to provide.

The heat-shrinkable polyester film of the present invention contains 0.01 to 1% by weight of an antioxidant, and a sample cut into a 10 cm × 10 cm square shape is immersed in warm water at 98 ° C. for 10 seconds and pulled up. Then, when the heat shrinkage rate in the maximum shrinkage direction is 40% or more when it is dipped in water at 25 ° C. for 10 seconds and pulled up, the heat shrinkable polyester film is 4 in an environment of a temperature of 30 ° C. and a relative humidity of 85%. The difference between the haze of the film after storing for a week and heat-shrinking the film after the storage under a predetermined condition and the haze of the film before the shrinking treatment is 5% or less, and the melt specific resistance value at 275 ° C. is It has a gist where it is 0.70 × 10 ⁸ Ω · cm or less.

  The heat-shrinkable polyester film of the present invention needs to contain 0.01 to 1% by weight of a heat stabilizer. By adding an antioxidant in this range to the composition described above, when discharged from an extruder, the heat resistance of the discharged molten film is improved, and the film forming time can be extended.

  Furthermore, the heat-shrinkable polyester film of the present invention is characterized in that 1 mol% or more of 1,4-cyclohexanedimethanol is contained in the polyhydric alcohol component constituting the polyester.

    The heat-shrinkable polyester film having the above characteristics is extremely low in shrinkage whitening, shrinkage spots, wrinkles, distortion, vertical sink marks, etc. even in a wide temperature range from low temperature to high temperature, especially in a low temperature range. It was possible to provide a heat-shrinkable polyester film having no shrinkage whitening and excellent shrinkage finish. In the case of a heat-shrinkable polyester film having the above composition, a sample cut into a 10 cm × 10 cm square shape is dipped in 98 ° C. warm water for 10 seconds and then dipped in 25 ° C. water for 10 seconds. The heat shrinkage rate in the maximum shrinkage direction when pulled up can ensure 40% or more.

In the heat-shrinkable polyester film of the present invention, it is preferable to further contain 2 mol% or more of a 1,4-butanediol component as a polyhydric alcohol component. By satisfying the composition concerned, the thermal shrinkage characteristic in the low temperature region can be further improved. Moreover, the adhesive force in a non-chlorine solvent improves and is preferable.

  In addition, since the present invention hardly causes shrinkage whitening, the difference between the haze after shrinkage and the haze before shrinkage is set to 5% or less.

  Here, the haze measurement is performed as follows. First, the heat-shrinkable polyester film is stored for 4 weeks in an environment of a temperature of 30 ° C. and a relative humidity of 85%. Next, using this film, a tube-shaped label is prepared so that the maximum shrinkage direction of the film is the circumferential direction by a solvent adhesion method or a heat seal method, and this label is covered with a glass bottle adjusted to a temperature of 40 ° C. Then, heat shrinkage is performed by applying hot air at 150 ° C. (wind speed 10 m / sec) for 13 seconds. From the heat-shrinkable labels (number of label samples: 10), film samples of the shrinkage spots are cut out. About these film samples, it measures based on JISK7136 and calculates | requires an average value. The haze difference is a numerical value obtained by subtracting the average value of 10 samples measured in accordance with JIS K 7136 for the sample cut from the heat-shrinkable polyester film immediately after production from the average value in this method.

Furthermore, the heat-shrinkable polyester film in the present invention is characterized in that the film has a melt specific resistance value at 275 ° C. of 0.70 × 10 ⁸ Ω · cm or less. As described above, the polyester is modified and the melt specific resistance value is lowered to increase the number of charge carriers and increase the electrostatic adhesion to the casting roll, enabling higher-speed production and improving the film quality such as thickness distribution. Can be improved. In order to lower the melting specific resistance value, it is preferable to contain alkaline earth M ² in the range of 40 to 400 ppm in the film. Furthermore, it is preferable to contain phosphorus atoms in the range of 20 to 600 ppm because the generation of foreign matter accompanying the addition of alkaline earth metal can be suppressed.

Furthermore, in the heat-shrinkable polyester film of the present invention, in addition to the above, the ratio (M ² / P) of the alkaline earth metal M ² and phosphorus atom in the film is preferably 1.2 to 5.0. It is a mode. By controlling the ratio between the alkaline earth metal M ² and the phosphorus atom within a predetermined range, not only the melting specific resistance value can be reduced, but also foreign matters in the film can be reduced.

The “maximum shrinkage direction” means the direction in which the sample is most contracted, and the thermal shrinkage rate in the maximum shrinkage direction is determined by the shrinkage rate in the vertical direction or the horizontal direction of the square sample. That is, the heat shrinkage rate (%) in the maximum shrinkage direction was measured by measuring the length of the film in the vertical and horizontal directions after immersing a 10 cm × 10 cm sample in 95 ° C. ± 0.5 ° C. water for 10 seconds under no load. By doing so, it can be obtained by the following equation.
Heat shrinkage rate = 100 × (length before shrinkage−length after shrinkage) ÷ (length before shrinkage)

In this case, it is preferable that adhesion is possible with a non-chlorine solvent.
Here, “adhesion with a non-chlorine solvent” means a case where the evaluation is “good”.
The film was joined into a tube shape using 1,3-dioxolane and tetrahydrofuran (THF) and left in an environment at a temperature of 23 ° C. and a relative humidity of 65% for 24 hours. A sample is taken by cutting to a width of 15 mm in the orthogonal direction, and a T-type peel test is performed on the bonded portion in the above direction according to JIS K 6854.
The number of test pieces was 20, and the test piece length was 60 mm, the distance between chucks was 20 mm, the test piece width was 15 mm, the temperature was 23 ° C., and the tensile speed was 200 mm / min.
The solvent adhesion was evaluated based on the following criteria.
Peel adhesion strength 3N / 15mm or more: ○
Peel adhesive strength 1N / 15mm or more, less than 3N / 15mm:
Peel adhesion strength less than 1N / 15mm: ×

  The heat-shrinkable polyester film of the present invention has excellent shrinkage properties at low temperatures without reducing heat resistance, and excellent shrinkage finish, and even when the film is stored for a long time, the occurrence of shrinkage whitening is extremely high. Therefore, it can be suitably used for label applications having excellent tear resistance and excellent productivity (reduction of lip streaks) and quality (suppression of pinner bubbles, uniformity of thickness, etc.).

Examples of the antioxidant include primary antioxidants (which are phenolic or amine-based and have radical scavenging and chain termination action), and secondary antioxidants (which are phosphorus-based and sulfur-based). Any of which can be used. Specific examples include phenolic antioxidants (eg, phenol type, bisphenol type, thiobisphenol type, polyphenol type, etc.), amine antioxidants (eg, diphenylamine type, quinoline type, etc.), phosphorus antioxidants, etc. Agents (for example, phosphite type, phosphonite type and the like), sulfur-based antioxidants (for example, thiodipropionic acid ester type and the like) and the like. Specifically, n-octadecyl-β- (4′-hydroxy-3,5′-di-t-butylphenyl) propionate, tetrakis [methylene-3- (3 ′, 5′-di-t-butyl- 4-hydroxyphenyl) propionate] (which is commercially available as “Irganox 1010” (trade name)), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane 1,3,5-tris (3,5-di-t-butyl-hydroxybenzyl) -S-triazine-2,4,6 (1H, 3H, 5H) -trione, 1,3,5-trimethyl- 2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene (which is commercially available as “Irganox 1330” (trade name)), tris (mixed mono and / or Or Ginoni Ruphenyl) phosphite, cyclic neopentanetetrayl bis (octadecyl phosphite) (this is commercially available as “Adekastab PEP-36” (trade name).
Tris (2,4-di-t-butylphenyl phosphite), 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, di-lauryl-thiodipropionate, di-myristyl- Examples thereof include thiodipropionate and di-stearyl-thiodipropionate. These antioxidants may be used alone or in combination of two or more. In particular, it is preferable to use a primary antioxidant and a secondary antioxidant in combination.

  The blending of the antioxidant into the polyester composition is not particularly limited. For example, there are a method of blending in a polyester production process, a method of blending at the time of forming a polyester film, and the blending form is a method of blending the above-mentioned antioxidant directly into polyester and melt-kneading; a high concentration There is a method of preparing a master batch containing an antioxidant in advance and blending the master batch.

  Content in the polyester composition of the said antioxidant needs to be 0.01 to 1 weight%, and 0.02 to 0.5 weight% is preferable. If it is less than 0.01% by weight, the effect of suppressing lip streaking cannot be obtained and sufficient film forming time cannot be secured. If it exceeds 1% by weight, the effect of suppressing the lip streaks obtained will not be improved any more, the antioxidant may be scattered in the film forming process, and the film production apparatus may be contaminated. Is also disadvantageous.

  The heat-shrinkable polyester film of the present invention is obtained when a sample cut into a 10 cm × 10 cm square shape is dipped in 98 ° C. warm water for 10 seconds and then dipped in 25 ° C. water for 10 seconds. The heat shrinkage rate in the maximum shrinkage direction must be 40% or more. When the heat shrinkage rate of the film is less than 40%, the heat shrinkage force of the film is insufficient, and when the film is covered and shrunk to a container or the like, the film does not adhere to the container and an appearance defect occurs, which is not preferable. A more preferable heat shrinkage rate is 50% or more, and further preferably 60% or more. The thermal shrinkage rate is preferably 85% or less.

  The present invention also provides a heat-shrinkable polyester film that hardly causes shrinkage whitening. As a guide, the heat-shrinkable polyester film is stored for 4 weeks in an environment of a temperature of 30 ° C. and a relative humidity of 85%. The difference between the haze of the film after heat-shrinking the film after storage under a predetermined condition and the haze of the film before shrinkage treatment is 5% or less. When the haze difference exceeds 5%, the transparency of the film coated and mounted on the transparent glass bottle is impaired, and the level is recognized as whitening by visual judgment. The haze difference is preferably as small as possible, more preferably 3% or less, and even more preferably 1% or less.

  Note that the heat-shrinkable polyester film is stored for 4 weeks in an environment of temperature 30 ° C. and relative humidity 85% before heat shrinkage. This is because it has been found that whitening easily occurs.

  In the present invention, when the difference between the haze after heat shrinkage measured by the above method and the haze immediately after production exceeds 5%, shrinkage whitening occurs when stored for a longer period of time. As a non-defective product. Therefore, in the present invention, the upper limit of the haze difference is set to 5%.

In the heat-shrinkable polyester film of the present invention, the melt specific resistance value at 275 ° C. is 0.70 × 10 ⁸ Ω · cm or less. The film of the present invention is usually produced through a process in which a molten film discharged from an extruder through a T die is electrostatically adhered to a casting roll and cooled on this roll. However, when the melt resistivity value exceeds 0.7 × 10 ⁸ Ω · cm, the electrostatic adhesion to the casting roll is poor, and air is locally trapped between the molten film surface and the casting roll surface. Since it is cast in a state, a so-called pinner bubble (streak-like defect) is generated on the surface of the cast film. The pinner bubble becomes more noticeable as the casting speed is increased. Further, when the melt specific resistance value exceeds 0.7 × 10 ⁸ Ω · cm and the electrostatic adhesion to the casting roll is not sufficient, the thickness of the cast unstretched film becomes uneven, and such unstretched When the film is stretched, the thin portion is further stretched, so that even in the stretched film obtained from such an unstretched film, the thickness unevenness remains in a more expanded state. As described above, in a film having poor castability, pinner bubbles are generated on the film surface, or thickness spots are generated, shrink finish after heat shrinkage tends to be inferior. The “unstretched film” includes a film on which a tension necessary for feeding the film in the manufacturing process is applied. Therefore, in order to suppress the occurrence of pinner bubbles and stably produce the film, it is necessary to reduce the production speed to such an extent that the discharged molten film can be sufficiently adhered to the casting roll, which increases the production cost. End up. The melting specific resistance value is preferably 0.50 × 10 ⁸ Ω · cm or less, more preferably 0.30 × 10 ⁸ Ω · cm or less. In addition, the fusion specific resistance value prescribed | regulated by this invention is a value measured by the method used in the Example mentioned later.

  In the present invention, in order to control the melt specific resistance value of the film within the above range, it is preferable to contain an alkaline earth metal compound and a phosphorus atom-containing compound in the film. The melting resistivity value can be reduced only with the alkaline earth metal compound, but the melting resistivity value can be remarkably lowered when the phosphorus atom compound coexists. Although it is not clear why the specific resistance of the melt can be significantly lowered by combining the alkaline earth metal compound and the phosphorus atom compound, the amount of foreign matter can be reduced by containing the phosphorus-containing compound, and the charge carrier It is estimated that the amount can be increased.

The content of the alkaline earth metal compound in the film is, for example, 40 ppm (mass basis) or more, preferably 50 ppm (mass basis) or more, more preferably 60 ppm (mass basis), based on the alkaline earth metal atom M ^2. ) That's it. If the amount of the alkaline earth metal compound is too small, the melting specific resistance value cannot be lowered. Note that even if the content of the alkaline earth metal compound is excessively increased, the effect of reducing the melt specific resistance value is saturated, and adverse effects such as generation of foreign substances and coloring are increased. Therefore, the content of the alkaline earth metal compound is, for example, 400 ppm (mass basis) or less, preferably 350 ppm, based on the alkaline earth metal atom M ^2.
(Mass basis) or less, more preferably 300 ppm (mass basis) or less.

The content of the phosphorus compound in the film is, for example, 10 ppm (mass basis) or more, preferably 15 ppm (mass basis) or more, more preferably 20 ppm (mass basis) or more, particularly 60 ppm (mass) based on the phosphorus atom P. Standard) or more. If the amount of the phosphorus compound is too small, the melting specific resistance cannot be lowered sufficiently, and the amount of foreign matter generated cannot be reduced. Even if the content of the phosphorus compound is excessively increased, the effect of reducing the melt specific resistance value is saturated. Furthermore, since the production of diethylene glycol is promoted and it is difficult to control the production amount, the physical properties of the film may be different from those planned. Therefore, the phosphorus compound content is, for example, 600 ppm (mass basis) or less, preferably 500 ppm (mass basis) or less, more preferably 450 ppm (mass basis) or less, particularly 400 ppm (mass basis), based on the phosphorus atom P. It is as follows.

When lowering the melt resistivity value of the film with an alkaline earth metal compound and a phosphorus compound, the mass ratio (M ² / P) between the alkaline earth metal atom M ² and the phosphorus atom P in the film is 1.2 or more ( Preferably it is 1.3 or more, more preferably 1.4 or more. By setting the mass ratio (M ² / P) to 1.2 or more, the melt specific resistance value can be significantly reduced. When the mass ratio (M ² / P) exceeds 5.0, the amount of foreign matter generated increases or the film is colored. Therefore, the mass ratio (M ² / P) is 5.0 or less, preferably 4.5 or less, and more preferably 4.0 or less.

In order to further reduce the melt specific resistance value of the film, it is desirable to contain an alkali metal compound in the film in addition to the alkaline earth metal compound and the phosphorus-containing compound. Alkali metal compounds cannot reduce the melt resistivity even if they are contained alone in the film, but by adding to the coexistence system of alkaline earth metal compounds and phosphorus-containing compounds, the melt resistivity can be significantly reduced. Can do. Although it is not clear about the reason, it is presumed that the melting specific resistance value is lowered by forming a complex of the alkali metal compound, the alkaline earth metal compound, and the phosphorus-containing compound.

The content of the alkali metal compound in the film is, for example, 0 ppm (mass basis) or more, preferably 5 ppm (mass basis) or more, more preferably 6 ppm (mass basis) or more, based on the alkali metal atom M ^1. 7 ppm (mass basis) or more. Even if the content of the alkali metal compound is excessively increased, the effect of reducing the melt specific resistance value is saturated, and further, the amount of foreign matter generated is increased. Therefore, the content of the alkali metal compound is, for example, 100 ppm (mass basis) or less, preferably 90 ppm (mass basis) or less, more preferably 80 ppm (mass basis) or less, based on the alkali metal atom M ¹ .

Examples of the alkaline earth metal compound include an alkaline earth metal hydroxide, alkoxide, aliphatic carboxylate (acetate, butyrate, etc., preferably acetate), aromatic carboxylate (benzoate), And salts with a compound having a phenolic hydroxyl group (such as a salt with phenol). Examples of the alkaline earth metal include magnesium, calcium, strontium, barium and the like (preferably magnesium). Preferred alkaline earth metal compounds include magnesium hydroxide, magnesium methoxide, magnesium acetate, calcium acetate, strontium acetate, barium acetate and the like, especially magnesium acetate. The alkaline earth metal compounds can be used alone or in combination of two or more.

Examples of the phosphorus compound include phosphoric acids (phosphoric acid, phosphorous acid, hypophosphorous acid, etc.), and esters thereof (alkyl esters, aryl esters, etc.), as well as alkylphosphonic acids, arylphosphonic acids, and esters thereof (alkyl esters). And aryl esters). Preferable phosphorus compounds include phosphoric acid, aliphatic esters of phosphoric acid (phosphoric acid alkyl esters, etc .; for example, phosphoric acid monomethyl ester, phosphoric acid monoethyl ester, phosphoric acid monobutyl ester, phosphoric acid mono C _1-6 Phosphoric acid tri-C ₁ such as alkyl ester, phosphoric acid dimethyl ester, phosphoric acid diethyl ester, phosphoric acid dibutyl ester, phosphoric acid diC _1-6 alkyl ester, phosphoric acid trimethyl ester, phosphoric acid triethyl ester, phosphoric acid tributyl ester _-6 alkyl esters, etc.), aromatic esters of phosphoric acid (such as mono-, di- or tri-C _6-9 aryl esters of phosphoric acid such as triphenyl phosphate, tricresyl phosphate), aliphatic esters of phosphorous acid ( Alkyl esters of phosphorous acid; for example, trimethyl phosphite, tributyl phosphite Mono-, di-, or tri-C _1-6 alkyl esters of phosphorous acid such as, alkyl phosphonic acids (C _1-6 alkyl phosphonic acids such as methyl phosphonic acid, ethyl phosphonic acid), alkyl phosphonic acid alkyl esters (methyl phosphonic acid) dimethyl, a C _1-6 mono- or di-C _1-6 alkyl esters of alkyl phosphonic acid such as ethylphosphonic acid dimethyl), aryl phosphonic acid alkyl ester (phenylphosphonic acid dimethyl, C _6-9 aryl such as phenyl phosphonic acid diethyl Examples include phosphonic acid mono- or di-C _1-6 alkyl esters), arylphosphonic acid aryl esters (such as C _6-9 arylphosphonic acid mono- or di-C _6-9 aryl esters such as phenylphosphonic acid diphenyl), and the like. . Particularly preferred phosphorus compounds include phosphoric acid and trialkyl phosphate (such as trimethyl phosphate). These phosphorus compounds can be used alone or in combination of two or more.

  Examples of the alkali metal compound include alkali metal hydroxide, carbonate, aliphatic carboxylate (acetate, butyrate, etc., preferably acetate), aromatic carboxylate (benzoate), phenolic hydroxyl group And a salt with a compound having a salt (such as a salt with phenol). Examples of the alkali metal include lithium, sodium and potassium (preferably sodium). Preferred alkaline earth metal compounds include lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, lithium acetate, sodium acetate, potassium acetate and the like, especially sodium acetate.

  Moreover, in this invention, it is suitable that it can adhere | attach with a non-chlorine-type solvent. The label is rolled into a cylindrical shape so that the maximum shrinkage direction of the heat-shrinkable polyester film of the present invention is the circumferential direction, and the ends are bonded to each other to create a tubular body. It is created by cutting. Adhesive solvents include aromatic hydrocarbons such as benzene, toluene, xylene and trimethylbenzene; halogenated hydrocarbons such as methylene chloride and chloroform; phenols such as phenol; furans such as tetrahydrofuran; 1,3-dioxolane. Organic solvents such as oxolanes are used, but in consideration of the generation of toxic substances caused by halogens such as chlorine atoms, it is preferable that they can be bonded with non-chlorine organic solvents, and in particular, from the viewpoint of safety Therefore, it is desirable to use tetrahydrofuran and 1,3-dioxolane.

  In addition, the present invention provides a heat-shrinkable polyester film having excellent shrinkage characteristics and shrinkage finish properties in a wide temperature range from low temperature to high temperature. It is preferable that the shrinkage and finish are visually evaluated and the shrinkage finish is 4 or more.

Here, the finish property is evaluated as follows. First, using a printing machine on the film, printing is performed in the order of grass, blue gold, and white. Next, using this film, a tube-like label was prepared so as to be in the maximum shrinkage direction of the film by a solvent adhesion method or a heat seal method, and this label was put on a glass bottle adjusted to a temperature of 60 ° C., and 130 ° C. , 160 ° C., 190 ° C. (wind speed 12 m / sec) is applied for 10 seconds to cause heat shrinkage. The shrinkage and finish of the entire label were visually evaluated in five stages (measurement number 200).
The criteria are as follows.
5: Best finish 4: Excellent finish 3: Some defects (within 2 locations)
2: There are defects (3-5 locations)
1: Many defects (over 6 locations)
As a result, 4 or higher was regarded as acceptable, and 3 or lower was regarded as defective. In addition, a fault refers to what generically refers to jumping, wrinkles, insufficient shrinkage, label edge folding, and shrinkage whitening.

  Next, the preferable composition of the heat-shrinkable polyester film of the present invention will be described. Examples of the polyester as the main constituent of the present invention include ethylene terephthalate, ethylene naphthalate, and ethylene isophthalate. Among them, ethylene terephthalate is mainly used from the viewpoint of film tear resistance, heat resistance, shrink finish, cost, and the like. It is preferable to contain the other monomer component mentioned later as a structural component. As other dicarboxylic acid components constituting the polyester, aromatic dicarboxylic acids or ester-forming derivatives thereof, or aliphatic dicarboxylic acids 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 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, and a polyvalent carboxylic acid such as trimellitic anhydride or pyromellitic anhydride may be used in combination as necessary.

  1,4-cyclohexanedimethanol has the effect of increasing the degree of amorphousization and developing heat shrinkability. Further, the use of 1,4-cyclohexanedimethanol improves the shrink finish and improves the solvent adhesion. In order to sufficiently obtain these effects, it is preferable to contain 1 mol% or more of 1,4-cyclohexanedimethanol out of 100% of the polyhydric alcohol component. Further, the shrinkage whitening phenomenon can be suppressed by using 1,4-cyclohexanedimethanol, and the resulting film satisfies the above-mentioned haze requirements.

  However, 1,4-cyclohexanedimethanol is preferably suppressed to 40 mol% or less in 100 mol% of the polyhydric alcohol component. If it exceeds 40 mol%, the shrinkage rate of the film becomes excessively high, and there is a risk of label displacement and pattern distortion in the heat shrinking process. Further, since the solvent resistance of the film is lowered, the film is whitened by an ink solvent (such as ethyl acetate) in the printing process, or the tear resistance of the film is lowered. Therefore, 37 mol% or less is more preferable, and 35 mol% or less is more preferable. In addition, when 1,4-cyclohexanedimethanol is less than 10% in 100 mol% of the polyhydric alcohol component, solvent adhesion and shrink finish cannot be obtained. It is preferable that 1, 4-cyclohexane dimethanol is 10 mol% or more out of 100% of the components. Further, the whitening phenomenon can be suppressed by using 1,4-cyclohexanedimethanol, and the obtained film satisfies the above-mentioned haze requirement. The amount of 1,4-cyclohexanedimethanol is more preferably 12 mol% or more, and further preferably 14 mol% or more.

  Polyesters copolymerized with 1,4-cyclohexanedimethanol differ greatly in thermal properties (melting point, crystallinity, glass transition temperature, etc.) compared to PET, and 1,4-cyclohexanedimethanol is in the molecular skeleton. It has hydrogen bonded to tertiary carbon, is susceptible to thermal oxidative degradation, and has low heat resistance. Therefore, in the polyester copolymerized with 1,4-cyclohexanedimethanol, when the above-mentioned additives are added to lower the melt specific resistance value, the thermal properties are greatly changed to further reduce the heat resistance, and the polyester is colored. Or viscosity reduction (molecular weight reduction) is likely to occur. In addition, poor operability (generation of lip streaks, contamination with oligomers, etc.) is likely to occur due to a decrease in heat resistance. One of the characteristics of the present invention is to improve the badness that is particularly manifested by the 1,4-cyclohexanedimethanol by adding a heat stabilizer or the like.

Other diol components constituting the polyester used in the present invention include ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, and 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, polyoxy Examples include ether glycols such as tetramethylene glycol, polyethylene glycol, bisphenol compounds or alkylene oxide adducts thereof, dimer diols, and the like. Trihydric or higher alcohols include trimethylolpropane, glycerin, pentaerythritol and the like. Among the polyhydric alcohol components, a neopentyl glycol component and the like are useful components for amorphizing the film, and can increase the heat shrinkability of the film. Moreover, a 1, 4- butanediol component, a propylene glycol component, etc. are useful components for lowering the glass transition temperature of the film and enabling heat shrinkage even at low temperatures. It is a preferred embodiment of the present invention to contain these components that lower the glass transition temperature, and the 1,4-butanediol component is preferably 2 mol% or more, more preferably 4 mol% or more, and even more preferably 6 in particular. It is preferable to contain mol% or more.
The ratio of the second alcohol component other than 1,4-cyclohexanedimethanol is, for example, about 15 to 80 mol%, preferably about 18 to 75 mol% in 100 mol% of the polyhydric alcohol component.

The polyester is not necessarily produced from 100 mol% of the polyvalent carboxylic acids and 100 mol% of the polyhydric alcohol, and the polyester unit may be formed by ring-opening polymerization of lactones (e.g., ε-caprolactone). . The combined use of lactones has a function of increasing the degree of amorphousness. When calculating the proportion (mol%) of each component in the polycarboxylic acid component and the polyhydric alcohol component, the ring-opening component of the lactone corresponds to both the polycarboxylic acid component and the polyhydric alcohol component. Calculate as you want.

  The polyester composition used in the present invention further includes, for example, inorganic lubricants such as titanium dioxide, fine-particle silica, kaolin, and calcium carbonate, and, for example, long chains to improve the slipperiness of the heat-shrinkable film. It is also preferable to contain an organic lubricant such as a fatty acid ester.

  In the heat-shrinkable polyester film of the present invention, inorganic particles, organic salt particles and crosslinked polymer particles can be added as a lubricant.

  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, riotium fluoride, etc. Is mentioned.

  In particular, in order to obtain a film with a lower haze while obtaining good handling properties, the inorganic particles are preferably agglomerated 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 order to disperse the lubricant uniformly in the film roll, after the lubricant is dispersed in the polyester by any of the methods described above, the shape of the polymer chip in which the lubricant is dispersed is matched and the raw material segregation in the hopper It is preferable to suppress this phenomenon. Taking polyester as an example, a polyester chip that is taken out in a molten state from a polymerization apparatus in a molten state after polymerization and immediately cooled with water and then cut with a strand cutter has a cylindrical shape with an elliptical bottom surface. It is preferable to use different raw material chips in which the average size of the major axis, minor axis, and cylindrical height of the elliptical bottom surface is within the range of the chip size ± 20% of the raw material species with the highest usage ratio, More preferably, the size is within a range of ± 15%.

  Moreover, although the thickness of the film which comprises the heat-shrinkable film roll of this invention is not specifically limited, For example, 10-200 micrometers is preferable as a shrink film for labels, and 20-100 micrometers is more preferable.

  Hereinafter, although the case where it comprises with a polyester-type heat-shrinkable film is mentioned as an example and demonstrated, this invention is not limited to this. The polyester raw material which comprises a polyester-type heat-shrinkable film may be individual, and may mix and use 2 or more types. When using 2 or more types together, a mixed system of polyethylene terephthalate and copolymerized polyester may be used, or a combination of copolymerized polyesters may be used. A combination with a homopolyester such as polybutylene terephthalate, polycyclohexylene dimethyl terephthalate, or polyethylene naphthalate may also be used. A method of mixing two or more kinds of polyesters having different Tg can also be an effective achievement means from the viewpoint of shrink finish. As a specific configuration, for example, a polyester having a dicarboxylic acid component consisting of terephthalic acid and 2,6-naphthalenedicarboxylic acid, and a diol component consisting of ethylene glycol, dimer diol and polytetramethylene glycol (molecular weight 650), and the like can be mentioned. There is a method of making these into a single copolymer system or a mixed system of two or more. The polyester can be produced by melt polymerization according to a conventional method, but is not limited thereto, and may be a polyester obtained by other polymerization methods. The degree of polymerization of the polyester is preferably from 0.3 to 1.3 in terms of intrinsic viscosity.

  The production method of the polyester 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, and a dimethyl ester of dicarboxylic acid and a glycol are transesterified. Examples include a so-called transesterification method in which polycondensation is performed later, and any production method can be applied.

  The timing of adding the above metal ions, phosphoric acid and derivatives thereof is not particularly limited. Generally, 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. Is preferred.

  Moreover, a ultraviolet absorber, an antistatic agent, a coloring agent, an antibacterial agent, etc. can also be added as needed. The preferred intrinsic viscosity for forming the film is not limited, but is usually 0.50 to 1.30 dl / g.

  The polyester raw material used for this invention is dried using dryers, such as a hopper dryer and a paddle dryer, or a vacuum dryer, and it extrudes in the form of a film at the temperature of 200-300 degreeC. Alternatively, an undried polyester raw material is similarly extruded into a film while removing moisture in a vented extruder. At this time, it is preferable to take measures to reduce the composition fluctuation of the polymer component described above. When extruding, any existing method such as a T-die method or a tubular method may be adopted. After extrusion, it is cooled rapidly to obtain an unstretched film. Stretching is performed on the unstretched film, but in order to achieve the object of the present invention, the lateral direction is practical as the main shrinking direction. For example, when the main shrinkage direction is the longitudinal direction, the film can be formed in accordance with a normal operation in addition to changing the stretching direction in the following method by 90 degrees.

In addition, when paying attention to uniforming the thickness distribution of the desired heat-shrinkable polyester film, the thermal conductivity coefficient is preliminarily applied in the preheating step prior to the stretching step when stretching in the transverse direction using a tenter. Is preferably heated at a low wind speed of 0.0013 calories / cm ² · sec · ° C. or less until the film temperature reaches Tg−20 ° C. to Tg + 60 ° C. Stretching in the transverse direction is 2.3 to 7.3 times, preferably 3.5 to 6.0 times at a temperature of Tg-30 ° C to Tg + 40 ° C, more preferably at a temperature of Tg-25 ° C to Tg + 35 ° C. . Thereafter, heat treatment is performed at a temperature of 60 ° C. to 8 ° C. while stretching 0 to 15% or relaxation of 0 to 15%. If necessary, heat treatment is further performed at a temperature of 40 ° C. to 100 ° C. to cause heat shrinkage. A conductive polyester film is obtained. In this transverse stretching process, it is preferable to take measures to suppress temperature fluctuations in the aforementioned process.

As a stretching method, not only horizontal uniaxial stretching with a tenter, but also stretching in the longitudinal direction is 1.03 times or more, preferably 1.05 times to 1.2 times. The biaxial stretching may be either sequential biaxial stretching or simultaneous biaxial stretching, and may be re-stretched as necessary. Further, in 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 adopted, the film roll of the present invention is subject to fluctuations in the film surface temperature measured at a fixed position in the preheating step, stretching step, etc., similarly to the transverse stretching. Within the range of the distance in the flow direction corresponding to the film winding length, the average temperature is preferably within ± 1 ° C, and more preferably within the average temperature ± 0.5 ° C. 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 in the stretching process is preferably 0.0037 J / cm ² · sec · ° C. or more. More preferably, the condition of 0.00544 to 0.00837 J / cm ² · sec · ° C. is good.

  Next, the present invention will be described in more detail using examples and comparative examples, but is not limited to the following examples. Moreover, the measuring method of the physical property of the film obtained by the Example and the comparative example is shown below.

(1) Composition A sample (chip or film) is dissolved in a solvent in which chloroform D (manufactured by Usolip) and trifluoroacetic acid D1 (manufactured by Usolip) are mixed at a ratio of 10: 1 (volume ratio) to prepare a sample solution. , NMR (“GEMINI-200”; manufactured by Varian) was used to measure the proton NMR of the sample solution under the measurement conditions of a temperature of 23 ° C. and an integration count of 64 times. Based on the peak intensity of protons measured by NMR measurement, the composition ratio of monomers constituting the sample was calculated.

(2) The heat shrinkage film was cut into a 10 cm × 10 cm square, heat-shrinked in 98 ° C. ± 0.5 ° C. warm water for 10 seconds under no load, and then 25 ° C. ± 0.5 ° C. After being immersed in water for 10 seconds, the length of the sample in the vertical and horizontal directions was measured, and the thermal shrinkage rate was determined according to the following formula.
Heat shrinkage rate (%) = (length before shrinkage−length after shrinkage) ÷ length before shrinkage × 100

(3) Haze A heat-shrinkable polyester film is stored for 4 weeks in an environment of a temperature of 30 ° C. and a relative humidity of 85%. Next, using this film, a tube-shaped label is prepared so that the maximum shrinkage direction of the film is the circumferential direction by a solvent adhesion method or a heat seal method, and this label is covered with a glass bottle adjusted to a temperature of 40 ° C. Then, heat shrinkage is performed by applying hot air at 150 ° C. (wind speed 10 m / sec) for 13 seconds. A film sample is cut out from each label (number of label samples: 10) after the heat shrinkage. About these film samples, it measures based on JISK7136 and calculates | requires an average value. The haze difference is a numerical value obtained by subtracting the average value of 10 samples measured in accordance with JIS K 7136 for the sample cut from the heat-shrinkable polyester film immediately after production from the average value in this method.

(4) Shrinkage finish Using a printer on the film, the ink is printed in the order of grass, blue gold, and white. Next, using this film, a tube-like label was prepared so as to be in the maximum shrinkage direction of the film by a solvent adhesion method or a heat seal method, and this label was put on a glass bottle adjusted to a temperature of 60 ° C., and 190 ° C. A hot air with a wind speed of 12 m / sec is applied for 10 seconds to cause heat shrinkage. The overall shrinkage and finish of this label were visually evaluated on a five-point scale. The criteria are as follows.
5: Best finish 4: Excellent finish 3: Some defects (within 2 locations)
2: There are defects (3-5 locations)
1: Many defects (over 6 locations)
As a result, 4 or higher was regarded as acceptable, and 3 or lower was regarded as defective.
In addition, a fault refers to what generically refers to jumping, wrinkles, insufficient shrinkage, label edge folding, and shrinkage whitening.

(5) Melting specific resistance value A pair of electrode plates was inserted into a sample (chip or film) melted at a temperature of 275 ° C., and a voltage of 120 V was applied. The current was measured, and the melt specific resistance value (Si; unit Ω · cm) was determined based on the following formula.
Si (Ω · cm) = (A / I) × (V / io)
[In the formula, A represents the electrode area (cm 2), I represents the inter-electrode distance (cm), and V represents the voltage (V
Io indicates current (A)]

(6) Metal component The contents of Na, Mg, and P contained in the sample (chip or film) were measured according to the following method.
[Na] 2 g of a sample was put in a platinum crucible and incinerated at a temperature of 500 to 800 ° C., then 5 ml of hydrochloric acid (concentration: 6 mol / L) was added and evaporated to dryness. The residue is dissolved in 10 ml of 1.2 mol / L hydrochloric acid, and the Na concentration is measured (calibration curve method) using an atomic absorption analyzer [“AA-640-12”; manufactured by Shimadzu Corporation.
[Mg] 2 g of a sample was placed in a platinum crucible and incinerated at a temperature of 500 to 800 ° C., and then 5 ml of hydrochloric acid (concentration: 6 mol / L) was added and evaporated to dryness. The residue was dissolved in 10 ml of 1.2 mol / L hydrochloric acid, and the Mg concentration was measured (calibration curve method) using an ICP emission spectrometer [“ICPS-200”; manufactured by Shimadzu Corporation).
[P] Using the sample, the phosphorus component in the sample was converted to normal phosphoric acid by any of the following methods (A) to (C). This orthophosphoric acid and molybdate were reacted in sulfuric acid (concentration: 1 mol / L) to obtain phosphomolybdic acid, and then reduced by adding hydrazine sulfate. The density | concentration of the produced heteropoly blue was calculated | required by measuring the light absorbency of 830 nm using the absorptiometer ["UV-150-02"; Shimadzu Corporation make] (calibration curve method).
(A) Put the sample and sodium carbonate in a platinum crucible and dry ash and decompose (B) Wet decomposition in sulfuric acid / nitric acid / perchloric acid system (C) Wet decomposition in sulfuric acid / perchloric acid system

(7) Film formation time While the above polyester is mixed and fed continuously at a predetermined ratio, a resin at 275 ° C. is melt-extruded from a T-die with an extruder and cooled by a casting roll whose surface temperature is controlled at 30 ° C. Thus, a film having a thickness of 180 μm was produced (casting speed: 50 m / min). The molten resin was visually observed to evaluate the time until lip streaks occurred and the appearance was poor.
○: 36 hours or more Δ: 24-36 hours ×: less than 24 hours

(8) Solvent adhesion The film was joined into a tube shape using 1,3-dioxolane and tetrahydrofuran (THF) and left in an environment of a temperature of 23 ° C. and a relative humidity of 65% for 24 hours. A sample is taken by cutting it to a width of 15 mm in the flow direction and the orthogonal direction at the time of processing, and a T-type peel test is performed on the bonded portion in the above direction according to JIS K 6854.
The number of test pieces was 20, and the test piece length was 60 mm, the distance between chucks was 20 mm, the test piece width was 15 mm, the temperature was 23 ° C., and the tensile speed was 200 mm / min.
The solvent adhesion was evaluated based on the following criteria.
Peel adhesion strength 3N / 15mm or more: ○
Peel adhesion strength 1N / 15mm or more and less than 3N / 15mm: △
Peel adhesion strength less than 1N / 15mm: ×

(Synthesis of polyester)
(Synthesis Example 1)
A stainless steel autoclave equipped with a stirrer, a thermometer and a partial recirculating cooler contains 100 mol% of dimethyl terephthalate (DMT) as a dicarboxylic acid component and 100 mol% of ethylene glycol (EG) as a polyhydric alcohol component. The polyhydric alcohol was charged so that the molar ratio was 2.2 times that of the methyl ester, 0.05 mol of zinc acetate as the transesterification catalyst (based on the acid component), and 0.025 mol% of antimony trioxide as the polycondensation catalyst. The transesterification reaction was carried out while adding methanol (to the acid component) and distilling off the produced methanol out of the system. Thereafter, a polycondensation reaction was performed at 280 ° C. under a reduced pressure condition of 26.7 Pa to obtain a polyester (A) having an intrinsic viscosity of 0.75 dl / g. The composition is shown in Table 1.

(Synthesis Examples 2 to 4)
By the same method as in Synthesis Example 1, polyesters (B) to (D) shown in Table 1 were obtained. In addition,
In the table, CHDM is 1,4-cyclohexanedimethanol, NPG is neopentyl glycol, BD is 1,4-butanediol, and DEG is diethylene glycol. The intrinsic viscosity of each polyester was (B): 0.77 dl / g, (C): 0.75 dl / g, (D): 0.72 dl / g. Each polyester was chipped. Table 1 shows the composition of each synthesis example.

  For the antioxidant, a master batch was prepared by adding 5% by mass of the antioxidant to be used to the polyester, and the necessary amount was used. As the method for adding the antioxidant, a twin screw extruder was used, and the antioxidant and the polyester resin were kneaded under a reduced pressure condition of 85 Pa at a resin temperature of 287 ° C., and then formed into chips.

  In addition, as for the inorganic lubricant, a master batch was prepared by adding 0.7% by mass of the inorganic lubricant used in the polyester (A) to the polyester (A), and the required amount was used. The lubricant was added in advance by dispersing the lubricant in ethylene glycol and polymerizing by the above method.

Example 1
Polyester A comprising 6 wt% of polyester A shown in Table 1 and 56 wt% of B, 14 wt% of C, 24 wt% of E, and 0.4 wt% of Irganox 1330 as an antioxidant, each preliminarily dried. It melt-extruded with a single screw extruder at 275 ° C. and then rapidly cooled to obtain an unstretched film having a thickness of 180 μm. This unstretched film was preheated until the film temperature reached 62 ° C., and then stretched 4.0 times at 60 ° C. in the transverse direction with a tenter. Next, heat treatment was performed at 74 ° C. for 14 seconds to obtain a heat-shrinkable polyester film having a thickness of 45 μm. Table 2 shows the physical property values of the film of the obtained film roll.

(Example 2)
Each separately pre-dried polyester A shown in Table 1 comprising 21 wt% of polyester A, 53 wt% of B, and 26 wt% of D, and containing 0.3 wt% of ADK STAB PEP-36 as an antioxidant at 275 ° C. After being melt-extruded by a single screw extruder, it was rapidly cooled to obtain an unstretched film having a thickness of 180 μm. This unstretched film was preheated until the film temperature reached 62 ° C., and then stretched 4.0 times at 60 ° C. in the transverse direction with a tenter to obtain a heat-shrinkable polyester film having a thickness of 45 μm. The physical properties of the film roll obtained are shown in Table 2.

(Comparative Example 1)
Polyester consisting of 6 wt% of polyester A, 56 wt% of B, 14 wt% of C, and 24 wt% of E as shown in Table 1, each preliminarily dried, is melt-extruded at 275 ° C by a single screw extruder and then rapidly cooled. Thus, an unstretched film having a thickness of 180 μm was obtained. This unstretched film was preheated until the film temperature reached 62 ° C., and then stretched 4.0 times in the transverse direction at 60 ° C. with a tenter to obtain a heat-shrinkable polyester film having a thickness of 45 μm. Table 2 shows the physical property values of the film of the obtained film roll.

(Comparative Example 2)
Polyester consisting of 21 wt% of polyester A shown in Table 1 and 53 wt% of B and 26 wt% of D shown in Table 1 was melt-extruded with a single screw extruder at 275 ° C and then rapidly cooled to obtain a thickness. An unstretched film of 180 μm was obtained. This unstretched film was preheated until the film temperature reached 62 ° C., and then stretched 4.0 times at 55 ° C. in the transverse direction with a tenter to obtain a heat-shrinkable polyester film having a thickness of 44 μm. The physical properties of the film roll obtained are shown in Table 2.

(Comparative Example 3)
Each separately pre-dried polyester A shown in Table 1 comprising 21 wt% of polyester A, 53 wt% of B, 26 wt% of D, and 0.05 wt% of Irganox 1330 as an antioxidant was obtained at 275 ° C. After melt extrusion with a shaft extruder, the film was quenched and a non-stretched film having a thickness of 180 μm was obtained. This unstretched film was preheated until the film temperature reached 80 ° C., and then stretched 4.0 times at 65 ° C. in the transverse direction with a tenter to obtain a heat-shrinkable polyester film having a thickness of 44 μm. Table 2 shows the physical property values of the film of the obtained film roll.

(Comparative Example 4)
Polyester consisting of 23 wt% of polyester A shown in Table 1, 23 wt% of C, and 24 wt% of D, each separately preliminarily dried, is melt-extruded with a single screw extruder at 275 ° C and then rapidly cooled to obtain a thickness An unstretched film of 175 μm was obtained. This unstretched film was preheated until the film temperature reached 72 ° C., and then stretched 4.0 times at 69 ° C. in the transverse direction with a tenter to obtain a heat-shrinkable polyester film having a thickness of 45 μm. Table 2 shows the physical property values of the film of the obtained film roll.

  The heat-shrinkable polyester film of the present invention has excellent shrink finish, and even when the film is stored for a long period of time, the occurrence of shrinkage whitening is extremely low, and the productivity (reduction of lip streaks) and quality are excellent. It is suitable for use and has high industrial utility value.

Claims (7)

In a heat-shrinkable polyester film, a sample containing 0.01 to 1% by weight of an antioxidant and cut into a 10 cm × 10 cm square shape was dipped in 98 ° C. warm water for 10 seconds and then pulled up, then 25 When heat-shrinkable polyester film is stored for 4 weeks in an environment where the maximum shrinkage in the direction of maximum shrinkage is 40% or higher when immersed in water at 10 ° C for 10 seconds and pulled up, the temperature is 30 ° C and the relative humidity is 85%. The difference between the haze of the film after heat-shrinking the film after storage under a predetermined condition and the haze of the film before shrinkage treatment is 5% or less, and the melting specific resistance value at 275 ° C. is 0.70. X10 ⁸ Ω · cm or less heat-shrinkable polyester film.   In a heat-shrinkable polyester film, a sample containing 0.01 to 1% by weight of an antioxidant and cut into a 10 cm × 10 cm square shape was dipped in 98 ° C. warm water for 10 seconds and then pulled up, then 25 When heat-shrinkable polyester film is stored for 4 weeks in an environment where the maximum shrinkage in the direction of maximum shrinkage is 40% or higher when immersed in water at 10 ° C for 10 seconds and pulled up, the temperature is 30 ° C and the relative humidity is 85%. The difference between the haze of the film after heat-shrinking the film after storage under a predetermined condition and the haze of the film before shrinkage treatment is 5% or less, and the content of the alkaline earth metal M2 in the film is A heat-shrinkable polyester film characterized by having 40 to 400 ppm and a phosphorus atom content of 20 to 600 ppm.   The heat-shrinkable polyester film according to claim 1 or 2, wherein the polyhydric alcohol component contains 1 mol% or more of 1,4-cyclohexanedimethanol component. Polyester film.   The heat-shrinkable polyester film according to any one of claims 1 to 3, wherein the polyhydric alcohol component further comprises 2 mol% or more of a 1,4-butanediol component.   The heat-shrinkable polyester film according to any one of claims 1 to 4, which is a heat-shrinkable polyester film and can be bonded with a non-chlorine organic solvent. The heat-shrinkable polyester according to any one of claims 1 to 4, wherein the ratio (M ² / P) of the alkaline earth metal M ² and phosphorus atom in the film is 1.2 to 5.0. Film.   The heat-shrinkable label created from the heat-shrinkable polyester film according to any one of claims 1 to 6.