JP2004066723A - Polyester-based heat shrinkable film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester-based heat shrinkable film which is softer than a heat shrinkable film made of vinyl chloride or copolymer polystyrene, preventing occurrence of injuries caused by an edge to be formed when the film is shrunk as a label for the purpose of an R seal, and is excellent in shrinkage. <P>SOLUTION: In the polyester-based heat shrinkable film, the sum of the tensile elasticity in the main shrinking direction of the film and the tensile elasticity in the direction orthogonal to the main shrinking direction of the film is less than 4,500 MPa. The polyester-based heat shrinkable film, when soaked in a hot water of 80°C, has a shrinkage in at least one direction of 10% or more in 10 seconds, and a haze of 25% or less in a thickness of 50μm. <P>COPYRIGHT: (C)2004,JPO

Description

【００６９】
【表３】

【００７０】
【発明の効果】
以上説明した本発明によれば、塩化ビニル製熱収縮性フィルムや共重合ポリスチレン製熱収縮性フィルムよりも軟らかく、従って、Ｒシール用途のラベルとしてフィルムを収縮させた際に出来るエッジによる怪我の発生を防止でき、しかも、収縮性に優れたポリエステル系収縮フィルムが提供され、本発明の工業的価値は顕著である。
【図面の簡単な説明】
【図１】熱収縮フィルムのＲシール用途の態様を示す概念図
【符号の説明】
Ａ：熱収縮性フィルム製の製袋品
Ｂ：容器
１：端部つの[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polyester-based heat-shrinkable film, and more particularly, has a suitable flexibility in both the longitudinal direction and the width direction, and can be shrunk using a general steam or hot-air shrink tunnel. The present invention relates to a heat-shrinkable polyester film suitably used for labels and food packaging.
[0002]
[Prior art]
Conventionally, a stretched film made of polyvinyl chloride or polystyrene has been mainly used as a shrink label for a glass bottle or a polyethylene terephthalate bottle or a shrink film for food packaging.
[0003]
By the way, in recent years, there has been a demand for a heat-shrinkable film using a polyester-based resin having excellent safety and hygiene properties and chemical resistance, and the use of a stretched film made of a polyester-based resin is increasing.
[0004]
However, the polyester-based heat-shrinkable films currently on the market have the following problems. In other words, since the material itself is inherently high in rigidity and is excessively oriented in order to exhibit shrinkage properties, other materials such as a heat-shrinkable film made of vinyl chloride or copolymer polystyrene are used as shrink films. Harder than heat-shrinkable film.
[0005]
Therefore, there is a concern that an edge formed when the film is shrunk as a label, particularly an "edge end" generated when overlapping shrinkage occurs. FIG. 1 is a conceptual diagram showing an embodiment of a heat-shrinkable film used for R-sealing. That is, the R-seal is an aspect of the overlap shrink, and is a method of heat-shrinking a bag-made product (A) made of a heat-shrinkable film having a head sealed in a curved shape over a container (B). It is. In the case of such an R seal application, "one end" (1) occurs at the shoulder of the container.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described circumstances, and has as its object the purpose of being softer than a polyester-based heat-shrinkable film. An object of the present invention is to provide a polyester-based shrinkable film which can be prevented and has excellent shrinkability.
[0007]
[Means for Solving the Problems]
As a result of various studies, the present inventors have obtained a finding that the above object can be easily achieved by maintaining the total of the elastic modulus in the vertical and horizontal directions at a certain value or less in the polyester film. Was completed.
[0008]
That is, the gist of the present invention is a polyester-based heat-shrinkable film, in which the sum of the tensile elastic modulus in the main shrinkage direction of the film and the tensile elastic modulus in a direction orthogonal to the direction is less than 4,500 MPa, at least. A polyester-based heat-shrinkable film characterized by having a shrinkage of 10% or more in 10 seconds when immersed in hot water at 80 ° C. in one direction and a haze of 25% or less at a thickness of 50 μm.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail. In the polyester-based heat shrinkable film of the present invention, the sum of the tensile elastic modulus in the main shrinkage direction of the film and the tensile elastic modulus in the direction orthogonal to the direction must be less than 4,500 MPa. If the sum of the tensile modulus and the tensile modulus is 4,500 MPa or more, the “ends” generated in the application of the R seal become hard and the object of the present invention cannot be achieved. The sum with the tensile modulus is preferably 3,500 MPa or less. The lower limit is usually 300 MPa.
[0010]
The polyester heat-shrinkable film of the present invention must have a shrinkage of 10% or more in 10 seconds when immersed in hot water at 80 ° C. in at least one direction. If the shrinkage is less than 10%, sufficient shrinkage characteristics cannot be obtained. The shrinkage is preferably 20% or more, and the upper limit is usually 60%.
[0011]
The polyester-based heat shrinkable film of the present invention has a haze at a thickness of 50 μm of 25% (preferably 15%) or less. This value means a value measured according to JIS K7105. When the haze is within the above range, the use of a packaging container, a label material, or the like can provide an effect of excellent transparency and excellent design. If the thickness is not 50 μm, it is determined by converting to a value at 50 μm.
[0012]
In the production of the polyester-based heat-shrinkable film of the present invention having the above-mentioned properties, the raw polyester-based resin is composed of a dicarboxylic acid unit and a diol unit, and a polyalkylene ether glycol is used as a copolymer component in an amount of 10 to 50 weight%. % Is preferably used.
[0013]
The starting material for the dicarboxylic acid unit is preferably an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid, and 80 mol% or more of the dicarboxylic acid unit is composed of the aromatic dicarboxylic acid or the alicyclic dicarboxylic acid. Is preferred.
[0014]
Specific examples of the aromatic dicarboxylic acid include, for example, terephthalic acid, isophthalic acid, orthophthalic acid, phenylenedioxydiacetic acid, 4,4′-diphenyldicarboxylic acid, and 4,4′-diphenoxyethanedicarboxylic acid , 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenyl sulfone dicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, etc., of which terephthalic acid is preferably used Is done.
[0015]
In addition, as the alicyclic dicarboxylic acid, specifically, for example, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and the like are exemplified, and among these, 1,4-cyclohexanedicarboxylic acid is preferable. Used for
[0016]
Further, dicarboxylic acids other than the above-mentioned dicarboxylic acids may be copolymerized as long as the effects of the present invention are not impaired. Examples of such dicarboxylic acids include, for example, aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid, azelaic acid, and sebacic acid.
[0017]
The constituent material of the diol unit is preferably an aliphatic diol or an alicyclic diol, and it is preferable that 80 mol% or more of the diol unit is composed of the aliphatic diol or the alicyclic diol.
[0018]
As the aliphatic diol, specifically, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5- Examples thereof include pentanediol, 1,6-hexanediol, 1,10-decanediol, 2,2-dimethyl-1,3-propanediol, diethylene glycol, and the like. Of these, ethylene glycol is suitably used.
[0019]
Specific examples of the alicyclic diol include, for example, 1,1-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, Examples thereof include 2-cyclohexanediol and 1,4-cyclohexanediol, among which 1,4-cyclohexanedimethanol is preferably used.
[0020]
The copolymerized polyester resin used in the present invention may further include, for example, 4,4′-dihydroxybiphenyl, 2,2-bis (4′-hydroxyphenyl) propane, and the like, as long as the effects of the present invention are not impaired. Aromatic diols such as 2,2-bis (4′-β-hydroxyethoxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-β-hydroxyethoxyphenyl) sulfonic acid, glycolic acid, p-hydroxybenzoate Monofunctional components such as acids, hydroxycarboxylic acids such as p-β-hydroxyethoxybenzoic acid and the like, alkoxycarboxylic acids, stearic acid, stearyl alcohol, benzyl alcohol, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid, and the like, tricarballylic acid , Hexanetricarboxylic acid, trimellitic acid, trimesic acid, pyro Trifunctional such as lithic acid, benzophenonetetracarboxylic acid, naphthalenetetracarboxylic acid, 1,2,6-hexanetriol, gallic acid, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, sorbitol, dipentaerythritol and polyglycerol The above polyfunctional components may be copolymerized.
[0021]
Specific examples of the polyalkylene ether glycol include, for example, polyethylene glycol, polypropylene glycol, polytrimethylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, blocks of ethylene oxide and propylene oxide or random copolymers. And polymers. These can be used in combination of two or more. Among these, polyethylene glycol and polytetramethylene ether glycol are preferred, and polytetramethylene ether glycol is particularly preferred.
[0022]
The number average molecular weight of the polyalkylene ether glycol is generally 500 to 2,500, preferably 500 to 2,300, and more preferably 600 to 2,000. When the number average molecular weight is less than 500, the tensile elastic modulus of the obtained polyester-based heat-shrinkable film becomes too high, while when it exceeds 2,500, the transparency of the obtained polyester-based heat-shrinkable film tends to decrease. There is.
[0023]
A plurality of polyalkylene ether glycols having different number average molecular weights can be used in combination. When two or more are used in combination, the number average molecular weight in a uniformly mixed state may be within the above range. The number average molecular weight of the polyalkylene ether glycol can be measured by a general method such as gel permeation chromatography.
[0024]
When the dicarboxylic acid unit and the diol unit are mainly terephthalic acid units and ethylene glycol units, the polyalkylene ether glycol is copolymerized in the copolymerized polyester resin at a ratio of usually 15 to 28% by weight, preferably 18 to 25% by weight. Is done. Further, when the dicarboxylic acid unit and the diol unit are mainly an alicyclic dicarboxylic acid unit and an alicyclic diol unit, they are usually copolymerized in the copolymerized polyester resin at 10 to 50% by weight, preferably 12 to 40% by weight. You.
[0025]
When the copolymerization amount of the polyalkylene ether glycol is less than the above range, the tensile elastic modulus of the obtained polyester-based heat-shrinkable film is too high. Properties tend to decrease, and the production of the copolymerized polyester resin itself becomes difficult.
[0026]
The copolymerized polyester resin used in the present invention can be manufactured in a batch or continuous manner by a conventional method for manufacturing a polyester resin, that is, a direct polymerization method or a transesterification method. Here, the polyalkylene ether glycol and any of the aforementioned copolymerization components can be added at any stage of the polycondensation reaction process.
[0027]
As the copolymerized polyester resin, an oligomer having a low degree of polymerization composed of an aromatic and / or alicyclic dicarboxylic acid and an aliphatic and / or alicyclic diol is produced in advance, and the oligomer and the polyalkylene ether glycol are produced. Can also be produced by polycondensation.
[0028]
The resin obtained by the polycondensation reaction is usually withdrawn in the form of a strand from an extraction port provided at the bottom of the polycondensation reaction tank, and cut with a cutter with or after cooling with water, and is pelletized. Further, by subjecting the pellets after the polycondensation to a heat treatment for solid phase polycondensation, the degree of polymerization can be further increased, and acetaldehyde, low molecular oligomer, and the like, which are reaction by-products, can be reduced.
[0029]
In the above production method, the esterification reaction is performed, if necessary, for example, in the presence of an esterification reaction catalyst such as an organic acid salt such as diantimony trioxide, antimony, titanium, magnesium, or calcium, or an organic metal compound. It is. On the other hand, the transesterification reaction is performed, if necessary, for example, in the presence of a transesterification catalyst such as an organic acid salt such as lithium, sodium, potassium, magnesium, calcium, manganese, titanium, or zinc or an organic metal compound. .
[0030]
The polycondensation reaction is carried out, for example, in the presence of phosphorous compounds such as orthophosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, esters and organic acid salts thereof, and, for example, diantimony trioxide, germanium dioxide, The reaction is performed in the presence of a metal oxide such as germanium oxide, or a polycondensation reaction catalyst such as an organic acid salt or an organic metal compound such as antimony, germanium, zinc, titanium, or cobalt. In particular, as the polycondensation reaction catalyst, one or more selected from tetrabutoxytitanate, antimony trioxide, and germanium dioxide are preferably used. Further, in order to promote defoaming in the polycondensation process, it is preferable to add an antifoaming agent such as silicone oil.
[0031]
The intrinsic viscosity of the copolymerized polyester resin used in the present invention measured at 30 ° C. in a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (weight ratio = 1/1) is usually 0.4 to 0.4. It is 1.5 dl / g, preferably 0.5 to 1.2 dl / g, more preferably 0.6 to 1.0 dl / g. When the intrinsic viscosity is less than 0.4 dl / g, the mechanical properties of the copolymerized polyester resin tend to be inferior. On the other hand, when the intrinsic viscosity exceeds 1.5 dl / g, molding of the copolymerized polyester resin becomes difficult.
[0032]
The copolymerized polyester resin used in the present invention preferably contains inorganic and / or organic fine particles, since it can impart blocking resistance, slipperiness, and the like when formed into a heat-shrinkable film. The content of the fine particles is usually 0.005 to 1% by weight, preferably 0.01 to 0.6% by weight, and more preferably 0.02 to 0.5% by weight, based on the whole film.
[0033]
Specific examples of the inorganic particles include, for example, silica, alumina, titania, kaolin, clay, calcium carbonate, calcium phosphate, lithium fluoride, and carbon black, as well as alkali metals, alkaline earth metals, and phosphorus at the time of polyester polymerization. Precipitated particles resulting from a catalyst such as a compound are included. Examples of the organic particles include various crosslinked polymers. The average particle diameter of these fine particles is usually 0.001 to 6 μm, preferably 0.005 to 4 μm, and more preferably 0.01 to 3 μm.
[0034]
The above average particle diameter means a 50% volume average particle diameter (d50) measured by a method such as a laser diffraction method, an electromagnetic wave scattering method such as a dynamic light scattering method, or a light transmission method such as a centrifugal sedimentation method. I do. When a difference occurs depending on the measurement method, a value obtained by a laser diffraction method is used.
[0035]
The blending of the fine particles with respect to the copolymerized polyester resin is usually performed by adding during the polycondensation process of the copolymerized polyester resin, but for particles other than precipitates caused by the catalyst and the like, the process of forming the copolymerized polyester resin is performed. May be added.
[0036]
Further, the copolymerized polyester resin used in the present invention is within a range not impairing the effects of the present invention, polyethylene, polypropylene, their maleic anhydride modified products, polyolefin resins such as ionomers, polyamide resins, polycarbonate resins, It may contain other thermoplastic resin such as polystyrene resin, thermoplastic elastomer, polyalkylene ether glycol which is not copolymerized with polyester resin, and the like.
[0037]
Further, the copolymerized polyester resin used in the present invention may be an antioxidant such as a hindered phenol type, a phosphite ester type or a thioether type, or a benzotriazole type, a benzophenone type, a benzoate type, a hindered amine type or a cyanoacrylate type. Stabilizers, inorganic and organic nucleating agents, molecular weight regulators, hydrolysis inhibitors, antistatic agents, lubricants, release agents, plasticizers, flame retardants, flame retardant aids, foaming agents, colorants, dispersion It may contain additives such as auxiliaries, and reinforcing materials such as glass fiber, carbon fiber, mica, and potassium titanate fiber.
[0038]
The above components may be added to the copolymerized polyester resin during the polycondensation process of the copolymerized polyester resin, or may be added during the molding process of the copolymerized polyester resin.
[0039]
The polyester heat-shrinkable film of the present invention is produced by using the above-mentioned copolymerized polyester resin as a raw material, for example, by the following film forming method.
[0040]
The raw resin is melt-extruded at a temperature of 200 to 300 ° C. The raw material resin may be a mixture of a plurality of types. As the extrusion method, a method such as a T-die method or a tubular method can be employed.
[0041]
In the case of the T-die method, after extrusion, it is rapidly cooled on a casting drum having a surface temperature of 15 to 80 ° C to form an unstretched film having a thickness of 30 to 300 µm. Then, the unstretched film is stretched under the conditions of a roll temperature of 60 to 120 ° C. and a stretching ratio of 1.0 to 1.3 (preferably 1.0 to 1.1) using a heated longitudinal stretching roll. I do. Next, using a tenter, the above uniaxially stretched film is stretched under the conditions of a stretching temperature of 60 to 120 ° C. and a stretching ratio of 1.7 to 7.0, and then heat-treated at a temperature of 55 to 100 ° C. and wound.
[0042]
In the above-mentioned film formation, in addition to directly using the above-mentioned copolymerized polyester resin as a raw material, a process of forming and processing this raw material into various molded products such as sheets, films, fibers, molded containers, and bottles. Recycled products such as scrap materials generated in the above can be used as raw materials. In addition to using the pulverized material or the like as a raw material, those obtained by melting once into a pellet shape or the like can be used as the raw material.
[0043]
The thickness of the polyester-based heat-shrinkable film of the present invention is usually 10 to 100 µm, preferably 30 to 70 µm.
[0044]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. The evaluation methods used in the following examples are as follows.
[0045]
(1) Intrinsic viscosity:
About 0.25 g of the copolymerized polyester resin was dissolved in about 25 ml of a mixed solvent of phenol / 1,1,1,2,2-tetrachloroethane (weight ratio 1/1) at 110 ° C. so as to be 1.0% by weight. Then, the mixture was cooled to 30 ° C., and measured at 30 ° C. with a fully automatic solution viscometer (“2CH DJ504” manufactured by Chuo Rika).
[0046]
(2) Copolymerization amount:
A sample solution obtained by dissolving the copolymerized polyester resin in trifluoroacetic acid is subjected to nuclear magnetic resonance (NMR). ¹ H was monitored and analyzed to determine the weight% of the polyalkylene ether glycol relative to the copolymerized polyester resin.
[0047]
(3) Shrinkage in the main shrinkage direction and vertical direction of the film:
The film was cut into a size of 70 mm in the measurement direction and 10 mm in a direction perpendicular to the measurement direction to prepare a sample. Then, mark lines at 50 mm intervals were attached in the sample measurement direction, immersed in a hot water bath at 80 ° C. for 10 seconds, and determined by the following equation. In the formula, L represents a mark line interval (unit: mm) after contraction.
[0048]
(Equation 1)
Shrinkage = [(50−L) / 50] × 100 (%)
[0049]
(4) Tensile modulus:
In parallel with the main shrinkage direction and the orthogonal direction of the film, test specimens each having a width of 5 mm and a length of 70 mm were collected. This was set in a tensile tester installed in a constant temperature room at 23 ° C. with a chuck of 50 mm. The stress-strain curve in the length direction was determined at a tensile test speed of 5 mm / min, and the tensile elastic modulus was determined from the following equation in the linear portion immediately after the start of the test.
[0050]
(Equation 2)
Tensile modulus =
Stress difference due to original average cross-sectional area between two points on a straight line / Strain difference between the same two points
[0051]
(5) Haze:
Haze was measured according to JIS K7105.
[0052]
(6) Hardness at the end:
Forming the shoulder bag at the mouth when making the overlap bag making product shown in FIG. The tactile sensation was evaluated for the hardness of the “one end” (1). The shrinking process was performed by using a steam shrink tunnel of “SKT-3000 type” manufactured by Keiyu System Co., Ltd., and by passing through the tunnel at a tunnel temperature of 85 ° C. for 10 seconds. Thereafter, the tactile sensation was evaluated for “one end”. The evaluation criteria were three levels shown in Table 1 below.
[0053]
[Table 1]
：: The resistance is small.
Δ: Some resistance was felt.
X: Strong resistance was felt.
[0054]
Example 1
Starting from 34.6 kg of terephthalic acid, 15.5 kg of ethylene glycol and 10.0 kg of polytetramethylene ether glycol (number average molecular weight 1000), 3.2 g of tetrabutoxytitanate, 1.3 g of orthophosphoric acid as a catalyst and a co-catalyst, Using 10.0 g of cobalt acetate, 50 g of amorphous silica having an average particle size of 2.4 μm (“Sylysia 320” manufactured by Fuji Silysia Ltd.), and copolyester resin by a direct polycondensation method at 270 ° C. and 400 Pa. Obtained. The copolymerized polyester resin was withdrawn from the polycondensation tank in the form of a strand, cooled, cut with a pelletizer, and recovered in the form of pellets. The intrinsic viscosity of the obtained copolymerized polyester resin was 0.79, and the copolymerization amount of polytetramethylene ether glycol was 19.8% by weight.
[0055]
The above resin is extruded from a 200 mm wide T-die die onto a cooling roll with a time discharge amount of 8 kg by a Toshiba Machine “TEM 58 mm” extruder while pulling a vacuum vent to obtain a sheet having a width of 150 mm and a thickness of 0.20 mm. Was. After that, the above-mentioned sheet was M. Using a “Film Stretcher” manufactured by Long Co., as a standard specification, stretch 4 times in the direction perpendicular to the casting extrusion direction at a stretching temperature of 53 ° C. and a stretching speed of 3000% / min. A film was obtained.
[0056]
Example 2
Example 1 was repeated except that 32.4 kg of terephthalic acid, 14.5 kg of ethylene glycol and 12.5 kg of polytetramethylene ether glycol (number average molecular weight 1000) were used as raw materials and the stretching temperature was changed to 56 ° C. In the same manner as in Example 1, a copolymerized polyester resin and a heat-shrinkable film were obtained. Table 3 shows the intrinsic viscosity of the copolymerized polyester resin, the copolymerization amount of polytetramethylene ether glycol, and the evaluation results of the heat-shrinkable film.
[0057]
Example 3
The dicarboxylic acid component is composed of 99.7 mol% (ratio to the total dicarboxylic acid component) of 1,4-cyclohexanedicarboxylic acid and 0.3 mol% (ratio to the total dicarboxylic acid component) of trimellitic acid. , 4-cyclohexanedimethanol, a copolymerized polyester resin having a copolymerization component of polytetramethylene ether glycol (number average molecular weight: 1000), wherein the proportion of polytetramethylene ether glycol in the copolymerized polyester resin is 25% by weight. A certain copolyester resin (“ECDEL PM9966” manufactured by Eastman) was used as a raw material resin. Then, a heat-shrinkable film was obtained in the same manner as in Example 1 except that the stretching temperature was changed to 60 ° C. in Example 1. Table 3 shows the intrinsic viscosity of the copolymerized polyester resin, the copolymerization amount of polytetramethylene ether glycol, and the evaluation results of the heat-shrinkable film.
[0058]
Comparative Example 1
Example 1 was repeated except that 30.3 kg of terephthalic acid, 13.5 kg of ethylene glycol and 15.0 kg of polytetramethylene ether glycol (number average molecular weight 1000) were used as raw materials and the stretching temperature was changed to 60 ° C. In the same manner as in Example 1, a copolymerized polyester resin and a heat-shrinkable film were obtained. Table 3 shows the intrinsic viscosity of the copolymerized polyester resin, the copolymerization amount of polytetramethylene ether glycol, and the evaluation results of the heat-shrinkable film.
[0059]
Comparative Example 2
The following copolymerized polyester resin A and copolymerized polybutylene terephthalate resin B were mixed at a ratio of 75:25 to obtain a raw material resin, and a sheet was formed in the same manner as in Example 1 except that the stretching temperature was changed to 60 ° C. The film was stretched to obtain a heat-shrinkable film. Table 3 shows the intrinsic viscosity of the raw material resin, the copolymerization amount of polytetramethylene ether glycol, and the evaluation result of the heat-shrinkable film.
[0060]
<Copolymerized polyester resin A>
The dicarboxylic acid component is terephthalic acid, the diol component is ethylene glycol, and the copolymerization components are 10.8 mol% of isophthalic acid (proportion to the total dicarboxylic acid component) and 19.2 mol% of 1,4-cyclohexanedimethanol (total diol). The ratio was adjusted to 0.3% by weight of amorphous silica having an average particle size of 2.4 μm (“Sylysia 320” manufactured by Fuji Silysia Ltd.) to a copolymerized polyester resin (proportion to the components).
[0061]
<Copolymerized polybutylene terephthalate resin B>
The dicarboxylic acid component is terephthalic acid, the diol component is 1.4-butanediol, and the copolymerization components are 7.5% by mole of isophthalic acid (ratio to the total dicarboxylic acid component) and polytetramethylene ether glycol (number average molecular weight: 1000). 8% by weight (proportion to the total diol component).
[0062]
Comparative Example 3
The following copolyester resin C and polybutylene terephthalate resin D were mixed at a ratio of 85:15 to obtain a raw material resin, and the sheeting and stretching were performed in the same manner as in Example 1 except that the stretching temperature was changed to 68 ° C. Was performed to obtain a heat-shrinkable film. Table 3 shows the evaluation results of the intrinsic viscosity of the raw material resin and the heat-shrinkable film.
[0063]
<Copolymer polyester resin C>
The dicarboxylic acid component is terephthalic acid, the diol component is ethylene glycol, and the copolymerization components are 9.6 mol% of isophthalic acid (relative to the total dicarboxylic acid component) and 20.5 mol% of 1,4-cyclohexanedimethanol (all diols). The ratio was adjusted to 0.3% by weight of amorphous silica having an average particle size of 2.4 μm (“Sylysia 320” manufactured by Fuji Silysia Ltd.) to a copolymerized polyester resin (proportion to the components).
[0064]
<Polybutylene terephthalate resin D>
"Novad Wool 5008" manufactured by Mitsubishi Engineering-Plastics Corporation
[0065]
Comparative Example 4
A copolyester resin and a heat-shrinkable film were prepared in the same manner as in Example 1 except that a polytetramethylene ether glycol having a number average molecular weight of 300 was used and the stretching temperature was changed to 65 ° C. Obtained. Table 3 shows the intrinsic viscosity of the copolymerized polyester resin, the copolymerization amount of polytetramethylene ether glycol, and the evaluation results of the heat-shrinkable film.
[0066]
Comparative Example 5
In Example 1, a copolymerized polyester resin and a sheet were obtained in the same manner as in Example 1, except that polytetramethylene ether glycol having a number average molecular weight of 3000 was used and the stretching temperature was changed to 65 ° C. . The sheet was not stretched, judging that the haze of the sheet was extremely poor and lacked practicality. Table 3 shows the evaluation results of the intrinsic viscosity of the copolymerized polyester resin and the copolymerization amount of polytetramethylene ether glycol.
[0067]
The meanings of the symbols in Table 3 are as shown in Table 2 below.
[0068]
[Table 2]

[0069]
[Table 3]

[0070]
【The invention's effect】
According to the present invention described above, it is softer than a heat-shrinkable film made of vinyl chloride or a heat-shrinkable film made of copolymerized polystyrene, and therefore, the occurrence of injuries due to edges caused when the film is shrunk as a label for R seal application. In addition, the present invention provides a polyester-based shrinkable film which can prevent the occurrence of shrinkage and has excellent shrinkability, and the industrial value of the present invention is remarkable.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing an embodiment of an R seal application of a heat shrinkable film.
[Explanation of symbols]
A: Bag-made product made of heat-shrinkable film
B: Container
1: One end

Claims (5)

A polyester heat-shrinkable film, wherein the sum of the tensile elastic modulus in the main shrinkage direction of the film and the tensile elastic modulus in a direction orthogonal to the direction is less than 4,500 MPa, and immersed in hot water at 80 ° C. in at least one direction. A polyester heat-shrinkable film having a shrinkage rate of 10% or more in 10 seconds and a haze at a thickness of 50 μm of 25% or less. 2. A copolymerized polyester resin comprising an aromatic dicarboxylic acid unit and an aliphatic diol unit and containing 15 to 28% by weight of a polyalkylene ether glycol having a number average molecular weight of 500 to 2,500 as a copolymerization component. The polyester-based heat-shrinkable film according to the above. A copolymerized polyester resin comprising an alicyclic dicarboxylic acid unit and an alicyclic diol unit and containing 10 to 50% by weight of a polyalkylene ether glycol having a number average molecular weight of 500 to 2,500 as a copolymerization component. Item 6. The polyester heat-shrinkable film according to item 1. The polyester heat-shrinkable film according to any one of claims 1 to 3, comprising a copolymerized polyester resin containing 0.005 to 1% by weight of particles having an average particle diameter of 0.001 to 6 µm. The polyester-based heat-shrinkable film according to any one of claims 1 to 4, which is used for an R seal.

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