JP4568043B2 - Polyester resin composition, heat-shrinkable polyester film comprising the resin composition, molded article and container - Google Patents

Description

  The present invention relates to a polyester-based resin composition suitable as a shrinkable label for a bottle, a heat-shrinkable polyester-based film composed of the composition, a molded article and a container using the film. More specifically, the present invention prevents the bottle from being deformed by heat when shrinkage starts at a low temperature in the shrink coating process of the molded product, and extremely reduces wrinkles, distortion, shrinkage spots, etc. of the film. The present invention relates to a polyester-based resin composition that can be suppressed, a heat-shrinkable film made of the resin composition, and a molded article and a container using the film.

  Conventionally, heat-shrinkable films made of polyvinyl chloride (hereinafter also referred to as “PVC”) have been widely used by users, including practical properties such as mechanical strength, rigidity, optical properties, shrinkage properties, and cost. In order to satisfy, it is widely used in shrink wrapping, shrink tying wrapping, labels for plastic containers, anti-destructive wrapping for glass containers, labels, cap seals, etc. However, PVC has excellent practical characteristics and cost as a raw material for heat-shrinkable films, but has disadvantages such as generation of toxic gas containing chlorine (dioxin) when incinerated after disposal. Therefore, in recent years, development of heat-shrinkable films using raw materials other than PVC is increasing.

  As one of raw materials other than PVC, a polystyrene-based heat-shrinkable film using a styrene-butadiene block copolymer (hereinafter also referred to as “SBS”) as a main raw material is known. SBS heat-shrinkable film has few shrinkage spots and wrinkles at the time of heat shrinkage, and has excellent shrinkage finish properties, but has poor rigidity at room temperature, large natural shrinkage, and poor fracture resistance. was there.

  Furthermore, a heat-shrinkable polyester film using a polyester resin other than PVC as a main raw material has also been proposed. Although this heat-shrinkable polyester film has very low room temperature rigidity and natural shrinkage rate, it is more likely to cause shrinkage spots and wrinkles during heat shrinkage compared to heat-shrinkable film made of PVC or SBS. There is a tendency to be inferior. However, for PET bottle labeling and the like, for which demand is expected to increase in recent years, a heat-shrinkable polyester film capable of obtaining a highly shrink-finished appearance in a relatively short time and at a relatively low temperature is eagerly desired.

In order to improve the above-mentioned drawbacks of heat-shrinkable polyester films, recently, a modified polybutylene terephthalate resin copolymerized with a predetermined amount of an aromatic dicarboxylic acid other than terephthalic acid and a modified polyester resin are mixed at a predetermined ratio. There has been proposed a method for improving the good shrinkage characteristics and impact resistance after heating by using the obtained resin as a raw material (see, for example, Patent Document 1). Furthermore, among polyhydric alcohol components, 1,4-cyclohexanedimethanol, 1,4-butanediol, copolymer polyester resin modified with polytetramethylene ether glycol is used as a raw material. A method for improving the properties and the like has also been proposed (see, for example, Patent Document 2). However, even with these methods, sufficient low temperature shrinkability and aging embrittlement could not be sufficiently suppressed.
JP 2002-212405 A (Claim 1, [0005]) JP2003-12833A (Claim 1, [0012])

  The present invention has been made in order to solve the above-described problems of the conventional heat-shrinkable polyester film, and the object of the present invention is to produce shrinkage spots, wrinkles, distortion, verticality when a heat-shrinkable film is produced. An object of the present invention is to provide a polyester-based resin composition that can provide excellent shrinkage finish without shrinkage and the like, and excellent breakage resistance with time by suppressing embrittlement promotion due to low Tg.

  Still another object of the present invention is to provide a heat-shrinkable polyester film, a molded product and a container comprising the above resin composition, which have excellent low-temperature shrinkage finish properties and suppression of embrittlement over time.

In order to solve the above problems, the present inventor has intensively studied the polyester resin composition, and as a result, when a heat-shrinkable film is produced using a polyester resin composition having a predetermined composition, The inventors have found that a film that can start shrinking from a low temperature and has little embrittlement with time is obtained, and the present invention has been completed.
That is, the object of the present invention is achieved by the following polyester resin composition.
(1) A polyester resin composition comprising the following component (A) and component (B).
(A) It contains at least terephthalic acid as a dicarboxylic acid component, ethylene glycol, 1,4-cyclohexanedimethanol and diethylene glycol as diol components, and 1,4-cyclohexanedimethanol is 15 mol% or more in 100 mol% of all diol components. Polyethylene terephthalate copolymer containing less than 25 mol% and containing 5 mol% or more and less than 15 mol% of diethylene glycol: 70 to 90 mass%
(B) terephthalic acid and isophthalic acid as dicarboxylic acid components, 1,4-butanediol and polytetramethylene glycol as diol components, and 2 to 8 mol% isophthalic acid in 100 mol% of all dicarboxylic acid components, Polybutylene terephthalate copolymer containing 1 to 5 mol% of polytetramethylene glycol in 100 mol% of all diol components: 10 to 30% by mass
(2) The resin composition according to (1), wherein the polytetramethylene glycol has a number average molecular weight of 500 to 2,000.
(3) The polyester resin composition according to (1) or (2), which is used for a heat shrinkable film.

Another object of the present invention is achieved by a heat-shrinkable polyester film, a multilayer film, a molded article and a container using the resin composition.
(4) A heat-shrinkable polyester film formed of the resin composition according to any one of (1) to (3).
(5) The shrinkage in the main film shrinkage direction after treatment in warm water at 70 ° C. for 10 seconds is 20% or more and less than 40%, and the shrinkage in the film main shrinkage direction after treatment in warm water at 80 ° C. for 10 seconds. The heat-shrinkable polyester film according to (4), wherein the rate is 40% or more and less than 70%.
(6) The difference between the shrinkage ratio in the main film shrinkage direction after treatment for 10 seconds in warm water at 70 ° C. and the shrinkage ratio in the film shrinkage direction for 10 seconds in warm water at 80 ° C. is 40% or less. The heat-shrinkable polyester film according to (4) or (5).
(7) After storage for 30 days in an environment of 30 ° C., a test piece cut out at 15 mm in the main shrinkage direction of the film and 50 to 150 mm in a direction orthogonal to the main shrinkage direction is 20 mm between chucks, 23 ° C. temperature, tensile Any of (4) to (6), when the tensile test is performed under the condition of a speed of 200 mm / min, the number of test pieces extending 50% or more of the original film length is 80% or more of the total number of test pieces. The heat-shrinkable polyester film described in 1.
(8) The heat-shrinkable polyester film according to any one of (4) to (7) obtained by stretching 4.0 to 6.0 times in the main shrinkage direction of the film.
(9) A heat-shrinkable multilayer polyester film comprising at least one heat-shrinkable polyester film according to any one of (4) to (8).
(10) The polyester resin composition according to any one of (1) to (3), the heat-shrinkable polyester film according to any one of (4) to (8), or the heat according to (9). Molded product formed using shrinkable laminated film.
(11) The molded product according to (10), wherein the molded product is a food container label.
(12) A container equipped with the molded product according to (10) or (11).

  According to the present invention, for example, when a heat-shrinkable film is used, it is possible to provide a polyester-based resin composition that can provide a film that exhibits high shrinkage at low temperatures and has little embrittlement over time.

  In addition, according to the present invention, when a molded product and a container are produced using the resin composition, it is possible to provide a molded product and a container that have good shrinkage finish properties and little embrittlement with time. .

  The contents of the polyester resin composition of the present invention (hereinafter referred to as “the resin composition of the present invention”), heat-shrinkable polyester film (hereinafter referred to as “the film of the present invention”), molded articles and containers are described in detail below. To do.

[Polyester resin composition / heat-shrinkable polyester film]
The resin composition of the present invention comprises a component (A) and a component (B), a polyethylene terephthalate copolymer (hereinafter referred to as “copolymer A”) as the component (A), and a polymer as the component (B). It contains a butylene terephthalate copolymer (hereinafter referred to as “copolymer B”).
The resin composition of the present invention can improve various thermal shrinkage behaviors by being composed of copolymer A and copolymer B. Copolymer A is greatly different in Tg from copolymer B. Therefore, by mixing both, for example, when used in a heat-shrinkable film, the temperature range in which the heat shrinkage rate of the film increases can be expanded. As a result, rapid shrinkage of the film from the start of heat shrinkage can be suppressed. That is, when the resin composition of the present invention contains a predetermined amount of copolymer A to suppress the crystallinity of copolymer B, for example, a heat-shrinkable film, the film has a sufficient shrinkage rate. In addition, it is possible to obtain a heat-shrinkable film that does not cause poor appearance even with a rapid heat treatment without a preheating step in the manufacturing process of the heat-shrinkable film and has little embrittlement over time.

<Copolymer A>
Copolymer A constituting the component (A) of the resin composition of the present invention contains at least terephthalic acid as a dicarboxylic acid component. Terephthalic acid is contained in a proportion of 90 to 100 mol%, preferably 95 to 100 mol%, more preferably 98 to 100 mol% in 100 mol% of all carboxylic acid components constituting the copolymer A. If terephthalic acid is included in the total carboxylic acid component in an amount of 90 mol% or more, high crystallinity can be obtained, so that sufficient strength can be secured when a heat-shrinkable film is produced.

  The dicarboxylic acid component constituting the copolymer A can contain an acid component other than terephthalic acid in a proportion of 10 mol% or less in 100 mol% of all the carboxylic acid components constituting the copolymer A. Examples of the acid component include isophthalic acid, orthophthalic acid, phenylenedioxydiacetic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenoxyethanedicarboxylic acid, and 4,4′-diphenyletherdicarboxylic acid. , 4,4′-diphenylsulfone dicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid or an ester-forming derivative thereof, or a fatty acid such as 1,4-cyclohexanedicarboxylic acid Examples thereof include cyclic dicarboxylic acids and aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid, azelaic acid, and sebacic acid. Of these, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and adipic acid are preferably used.

  Copolymer A contains at least ethylene glycol, 1,4-cyclohexanedimethanol and diethylene glycol as diol components. Ethylene glycol is contained in 60 to 80 mol%, preferably 65 to 77 mol%, more preferably 68 to 75 mol% in 100 mol% of all diol components constituting the copolymer A. Since high crystallinity can be obtained by including 60 mol% or more of ethylene glycol in 100 mol% of all diol components, sufficient strength can be secured when a heat-shrinkable film is produced, and the upper limit is 80 mol%. As a result, crystallization can be reduced and amorphous can be provided.

  1,4-cyclohexanedimethanol contained in the copolymer A is 15 mol% or more and less than 25 mol%, preferably 16 to 23 mol%, more preferably 100 mol% of all diol components constituting the copolymer A. Can be contained in an amount of 17 to 21 mol%. By making the content of 1,4-cyclohexanedimethanol in all diol components 15 mol% or more, when a heat-shrinkable film is produced, good impact resistance can be expressed, and the upper limit is further 25 mol%. By making it less than, the fluctuation | variation of the flow characteristic at the time of a fusion | melting can be suppressed.

  The diethylene glycol contained in the copolymer A is 5 mol% or more and less than 15 mol%, preferably 6 to 13 mol%, more preferably 7 to 11 mol%, in 100 mol% of all diol components constituting the copolymer A. included. By making the content of diethylene glycol 5 mol% or more, the resulting heat-shrinkable film can be heat-shrinked well at low temperatures, and if it is less than 15 mol%, the resulting heat-shrinkable film becomes brittle over time. Can be suppressed.

  The diol component constituting the copolymer A contains other diol components in addition to the ethylene glycol, 1,4-cyclohexanedimethanol and diethylene glycol as long as the total diol component is within a range of 100 mol%. You can also. Examples of such diol components include 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexane. Aliphatic diols such as diol, 1,10-decanediol, 2,2-dimethyl-1,3-propanediol; 4,4′-dihydroxybiphenyl, 2,2-bis (4′-hydroxyphenyl) propane, 2 , 2-bis (4′-β-hydroxyethoxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-β-hydroxyethoxyphenyl) sulfone, etc .; glycolic acid, p-hydroxybenzoic acid , P-β-hydroxyethoxybenzoic acid and other hydroxycarboxylic acids and alkoxycarboxylic acids; Monofunctional components such as acid, stearyl alcohol, benzyl alcohol, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid; tricarbaric acid, hexanetricarboxylic acid, trimellitic acid, trimesic acid, pyromellitic acid, benzophenonetetracarboxylic acid, naphthalenetetra Trifunctional or more polyfunctional components such as carboxylic acid, 1,2,6-hexanetriol, gallic acid, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, sorbitol, dipentaerythritol, polyglycerol; 1,1- Cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,2-cyclohexanediol, 1,4-cyclohexanedi And alicyclic diols such Lumpur, and among them 1,3-propanediol, 1,4-butanediol, it is preferable to use 1,4-cyclohexanediol.

  The glass transition temperature (Tg) of the copolymer A is desirably as low as possible so that it can start shrinking at a low temperature when it is a heat-shrinkable film, and is usually 70 ° C. or lower, preferably 65 ° C. or lower. When Tg exceeds 70 ° C., the shrinkage start temperature is high when the film is a heat-shrinkable film, and it may be difficult to attach it to a container or the like. In addition, the intrinsic viscosity (IV) of the copolymer A is 0.6 to 1 when measured in a solvent at 30 ° C. in a phenol / 1,1,2,2-tetrachloroethane (a mass ratio of 1: 1). 0 dl / g, preferably 0.7 to 0.9 dl / g.

<Copolymer B>
Copolymer B constituting the component (B) of the resin composition of the present invention contains at least terephthalic acid and isophthalic acid as the dicarboxylic acid component. The terephthalic acid is contained in a proportion of 90 to 98 mol%, preferably 92 to 97 mol%, more preferably 94 to 96 mol%, in 100 mol% of all dicarboxylic acid components constituting the copolymer B. If terephthalic acid is included in 90 mol% or more of all dicarboxylic acid components, high crystallinity can be obtained, so that sufficient strength can be secured when a heat-shrinkable film is formed.

  The isophthalic acid contained in the copolymer B together with the terephthalic acid is 2 to 10 mol%, preferably 2 to 8 mol%, more preferably 2 to 6 in 100 mol% of the total dicarboxylic acid constituting the copolymer B. Contains mol%. If 2% by mole or more of isophthalic acid is contained in all the dicarboxylic acid components, the crystallinity can be prevented from becoming too high, and good printing and sealing properties can be obtained when it is formed into a film. If the upper limit of isophthalic acid is 10 mol%, a copolymer having good fracture resistance can be obtained.

  The copolymer B can further contain other dicarboxylic acid components in the range of 100 mol% in total of the dicarboxylic acid, if necessary, in addition to the terephthalic acid and isophthalic acid. Examples of such a dicarboxylic acid component include orthophthalic acid, phenylenedioxydiacetic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenoxyethanedicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 4 , 4′-diphenylsulfone dicarboxylic acid, aromatic dicarboxylic acid such as 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid or ester-forming derivative thereof; alicyclic dicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid Acids: Aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid and the like.

  Copolymer B contains at least 1,4-butanediol and polytetramethylene glycol as the diol component. Among the diol components, 1,4-butanediol is contained in a proportion of 95 to 99 mol%, preferably 96 to 98 mol%, more preferably 97 to 98 mol%, in 100 mol% of all diol components. If the content of 1,4-butanediol is 95 mol% or more, high crystallinity can be obtained, so that sufficient strength can be secured when a heat-shrinkable film is produced. Moreover, if the content rate of 1, 4- butanediol shall be 99 mol% or less, a time-dependent brittle deterioration can be suppressed.

  The polytetramethylene glycol is contained in a proportion of 1 to 5 mol%, preferably 1.5 to 4 mol%, more preferably 2 to 3 mol% in 100 mol% of all diol components contained in the copolymer B. It is. If the content of polytetramethylene glycol is 1 mol% or more, when a heat-shrinkable film is produced, the rigidity of the film does not become too high, and if the upper limit is 5 mol%, the transparency is high. A film is obtained.

  The molecular weight of the polytetramethylene glycol is not particularly limited, but a number average molecular weight of 500 to 2,000, preferably 700 to 1,600, more preferably 800 to 1,200 is preferably used. If the polytetramethylene glycol has a number average molecular weight of 500 or more, when a heat-shrinkable film is produced, the tensile elastic modulus of the film does not become too high, and the number average molecular weight is 2,000 or less. Thus, a heat-shrinkable film having good transparency can be obtained.

  Moreover, the said polytetramethylene glycol can also use together multiple types from which a number average molecular weight differs. When a plurality of types are used in combination, the number average molecular weight in a uniformly mixed state is preferably within the above range. The number average molecular weight of polytetramethylene glycol can be measured by a general method such as gel permeation chromatography.

  In addition to the diol component, the copolymer B can be used in combination with other diol components within a range of 100 mol% as a whole. Specific examples include polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polyhexamethylene glycol, a block or random copolymer of ethylene oxide and propylene oxide, and the like. These diol components can be used in combination of two or more.

  Further, other diol components that can be used in combination include, for example, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 1, 6-hexanediol, 1,10-decanediol, 2,2-dimethyl-1,3-propanediol, aliphatic diols such as diethylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4′-hydroxy) Aromatic diols such as phenyl) propane, 2,2-bis (4′-β-hydroxyethoxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-β-hydroxyethoxyphenyl) sulfone; glycolic acid, Hydroxycarbo such as p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid Monofunctional components such as stearic acid, stearyl alcohol, benzyl alcohol, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid; tricarbaric acid, hexanetricarboxylic acid, trimellitic acid, trimesic acid, pyromellitic acid, Trifunctional or more polyfunctional compounds such as benzophenone tetracarboxylic acid, naphthalene tetracarboxylic acid, 1,2,6-hexanetriol, gallic acid, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, sorbitol, dipentaerythritol, polyglycerol, etc. Functional component: 1,1-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanediol, 1,4-cyclohexanedi And alicyclic diols such Lumpur like.

  The glass transition temperature (Tg) of the copolymer B is desirably as low as possible in order to have low temperature heat shrinkability, and is usually 45 ° C. or lower, preferably 40 ° C. or lower. When Tg exceeds 45 ° C., when the film is a heat-shrinkable film, the shrinkage start temperature is high, and it becomes difficult to attach it to a container or the like. In addition, the intrinsic viscosity (IV) of the copolymer B is 0.7 to 1. When measured in a solvent at 30 ° C. in a phenol / 1,1,2,2-tetrachloroethane (a mass ratio of 1: 1). 0 dl / g, preferably 0.8 to 0.9 dl / g.

  The resin composition of the present invention comprises the copolymer A and the copolymer B, and the content of each copolymer is such that the copolymer A is 70 to 90% by mass, preferably 75 to 90% by mass. More preferably, it is 80-90 mass%, and the copolymer B is 10-30 mass%, Preferably it is 10-25 mass%, More preferably, it is 10-20 mass%. The film of the present invention is obtained by mixing copolymer A and copolymer B within the above-mentioned range, resulting in low-temperature high-shrinkage that cannot be obtained with a heat-shrinkable film consisting of copolymer A alone or copolymer B alone. Breaking resistance can be expressed. That is, by setting the lower limit of the content of copolymer A to 70% by mass, when a heat-shrinkable film is obtained, a sufficient shrinkage rate and an appropriate sealing property in a high temperature range can be obtained, and the upper limit is 90% by mass. By setting the ratio to%, it is possible to suppress the rise of the rapid shrinkage rate of the film and to hardly cause poor appearance such as uneven shrinkage. Further, by setting the lower limit of the content of the copolymer B to 10% by mass, shrinkage in the low temperature range can be obtained, and rapid shrinkage in the high temperature range can be suppressed to suppress the shrinkage unevenness and make it difficult to break. it can. Further, by setting the upper limit of the copolymer B to 30% by mass, the produced film does not shrink at room temperature, and dimensional stability at room temperature can be obtained.

  In the present invention, the copolymer A and the copolymer B are basically a polyester resin composed of a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of ethylene glycol or butanediol. It can manufacture by using this manufacturing method.

  That is, a dicarboxylic acid component mainly composed of terephthalic acid and a diol component mainly composed of ethylene glycol or butanediol are esterified in an esterification reaction tank, and the resulting esterification reaction product is transferred to a polycondensation reaction tank. Obtained by subjecting a dicarboxylic acid component mainly composed of an ester derivative of terephthalic acid and a diol component mainly composed of ethylene glycol or butanediol to an ester exchange reaction in an esterification reaction tank. Transesterification method in which transesterification reaction product is transferred to polycondensation reaction tank and polycondensation, dicarboxylic acid component mainly composed of terephthalic acid is dispersed in diol component mainly composed of ethylene glycol or butanediol in slurry preparation tank The slurry thus obtained is slurried in the esterification reaction tank. The resulting esterification reaction product or transesterification reaction product is continuously added and esterified under normal pressure, and the resulting reaction product is continuously or / and stepwise added to the polycondensation reaction tank. Any of continuous direct polymerization methods such as transfer and polycondensation can be employed.

  Usually, the copolymer obtained by the polycondensation reaction is extracted in the form of a strand from an extraction port provided at the bottom of the polycondensation reaction tank, and is cooled with water or after water cooling and then cut into a pellet by cutting with a cutter. However, the degree of polymerization can be increased by subjecting the pellets after polycondensation to heat treatment and solid phase polymerization, and the reaction by-products such as acetaldehyde and low-molecular oligomers can be reduced.

In the production method, the esterification reaction is performed at about 200 to 270 ° C. in the presence of an esterification catalyst such as antimony trioxide or an organic acid salt such as antimony, titanium, magnesium, or calcium, if necessary. At a temperature of about 1 × 10 ⁵ to 4 × 10 ⁵ Pa. In addition, the transesterification reaction is performed at a temperature of about 200 to 270 ° C. in the presence of an ester exchange catalyst such as an organic acid salt such as lithium, sodium, potassium, magnesium, calcium, manganese, titanium, or zinc, as necessary. It can also be performed under a pressure of about 1 × 10 ⁵ to 4 × 10 ⁵ Pa.

The polycondensation reaction is performed, for example, in the presence of phosphorus compounds such as orthophosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, and esters and organic acid salts thereof, and for example, antimony trioxide, germanium dioxide, germanium tetroxide, etc. metal oxides, or antimony, germanium, zinc, titanium, in the presence of a polycondensation catalyst such as an organic acid salt such as cobalt, a temperature of about ^{240~290 ℃, 1 × 10 2 ~2} × 10 3 Pa about Under reduced pressure.

Solid phase polymerization is performed at a temperature of about 120 to 200 ° C. for 1 minute or longer, and after pre-crystallization, and then at a temperature of about 180 to 240 ° C. under an inert gas atmosphere such as nitrogen gas, Alternatively, and / or under reduced pressure of about 1 × 10 ² to 2 × 10 ³ Pa.

  The resin composition of the present invention is a polyolefin resin such as polyethylene, polypropylene, and their maleic anhydride-modified products, ionomers, polyamide resin, polycarbonate resin, polystyrene resin, etc., as long as the effects of the present invention are not impaired. It may contain other thermoplastic resins and thermoplastic elastomers, and further, antioxidants such as hindered phenols, phosphites, thioethers, benzotriazoles, benzophenones, benzoates, hindered amines , Light stabilizers such as cyanoacrylates, inorganic and organic crystal nucleating agents, molecular weight modifiers, hydrolysis agents, antistatic agents, lubricants, mold release agents, plasticizers, flame retardants, flame retardant aids , Additives such as foaming agents, colorants, dispersion aids, glass fibers, carbon fibers, mica, titanic acid It may contain a reinforcing material such as Li fiber.

  Since the resin composition of the present invention contains the copolymer A at a predetermined ratio with respect to the mass of the copolymer B, when the heat-shrinkable film is used, it is treated in warm water at 70 ° C. for 10 seconds. The shrinkage rate in the subsequent main film shrinkage direction is 20% or more and less than 40%, preferably 25 to 37%, and more preferably 30 to 35%. When the resin composition of the present invention is a heat-shrinkable film, the shrinkage rate in the main shrinkage direction is 20% at 70 ° C., which is a relatively low temperature, so that the resin composition can be gradually shrunk from a low temperature, In addition, since the upper limit is less than 40%, there is an advantage that a gentle rise in shrinkage is observed in a low temperature range and wrinkles are not easily generated during shrinkage.

  Furthermore, in the resin composition of the present invention, the shrinkage in the film main shrinkage direction after treatment for 10 seconds in warm water at 80 ° C. is 40 to 70%, preferably 45 to 60%, more preferably 50 to 55%. . The film of the present invention has a shrinkage ratio of 40% or more in the main shrinkage direction at a relatively high temperature of 80 ° C., and thus can be shrunk and covered even in a container having a complicated shape. Since it is 70%, a gentle contraction curve can be obtained, and generation of wrinkles and the like can be suppressed during contraction.

  In the film of the present invention, the difference in shrinkage ratio in the main film shrinkage direction between 70 ° C. and 80 ° C. is 40% or less, preferably 30% or less, more preferably 25% or less. If the difference in shrinkage ratio in the main film shrinkage direction between 70 ° C. and 80 ° C. is 40% or less, rapid shrinkage when the film is heated from the low temperature region to the high temperature region can be suppressed. For this reason, for example, when a container filled with the contents in the labeling process is shrunk through a shrinker, the shrinking of the label is started at a low temperature, and the shrinkage gradually proceeds as the temperature rises while passing through the shrinker. Products that are free from shrinkage spots and wrinkles can be obtained.

  Moreover, when the resin composition of the present invention is a heat-shrinkable film, the average shrinkage in the direction perpendicular to the main film shrinkage direction after treatment in warm water at 70 to 90 ° C. for 10 seconds is preferably 5% or less. Is 4% or less, more preferably 3% or less. If the average shrinkage in the direction perpendicular to the film main shrinkage direction is 5% or less, the label vertical direction will be damaged, and shrinkage spots and wrinkles will not easily occur especially in the shrinkage finish at 70 to 90 ° C. Can be improved.

  Next, although the manufacturing method of the film of this invention is demonstrated concretely, the manufacturing method of this invention is not limited to this.

  The film of the present invention can be produced by melt-extruding the resin composition of the present invention at 200 to 320 ° C. In the melt extrusion, a known method such as a T-die method or a tubular method can be used. When using 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 100 to 300 μm. The obtained unstretched film is stretched using a heated stretching roll or a tenter. The film is stretched by simultaneous biaxial stretching, sequential biaxial stretching, and uniaxial stretching, and either the stretching in the transverse direction or the stretching in the longitudinal direction may be performed first. For example, an unstretched film is stretched longitudinally at a roll temperature of 60 to 120 ° C. at a roll temperature of 60 to 120 ° C., preferably 1.0 to 1.5 times using a heated longitudinal stretching roll. After longitudinal stretching, the film is stretched by using a tenter at a stretching temperature of 60 to 120 ° C. at a stretching temperature of 1.7 to 7.0 times, preferably 4.0 to 6.0 times, and heat treated at a temperature of 60 to 100 ° C. take. If the draw ratio is 1.7 times or more, the thickness of the film tends to be uniform, and if it is 7.0 times or less, an appropriate contraction stress tends to be obtained. This tendency is 4.0 to 6.0 times. This is particularly remarkable in the range of. The stretching is performed at a stretching speed of 1,000 to 5,000% / min, preferably 2,000 to 4,000% / min. If the stretching speed is 2,000% / min or more, the productivity is good, and if the stretching speed is 4,000% / min or less, the thickness of the film tends to be uniform.

  Here, among the various characteristics of the film, since the shrinkage ratio mainly depends on the draw ratio and the draw temperature, it is preferably stretched at a high magnification and at a low temperature from the viewpoint of increasing the shrinkage ratio in the main shrinkage direction. On the other hand, the shrinkage stress mainly depends on the stretching temperature. The higher the magnification and the lower temperature stretching, the larger the shrinkage stress, and the influence of the heat treatment after stretching (annealing, particularly relaxation heat treatment). In order to set the shrinkage more smoothly, one method is to adjust the draw ratio while stretching at a slightly high temperature, and heat treatment is performed to improve the flatness of the film after stretching and to adjust the shrinkage rate. When it is performed, it is performed at a low temperature that does not promote crystallization of the polyester. Thereby, it is possible to obtain a film exhibiting a gentle shrinkage characteristic while suppressing a shrinkage stress that greatly affects the behavior of the film at the time of heat shrinkage. Specific temperature conditions can be appropriately set according to the type of polyester used.

  In the present invention, during the stretching step, before or after stretching, one or both surfaces of the film can be subjected to surface activation treatment such as corona discharge treatment to improve the adhesion of the film to the printed layer. Further, during the stretching step, before or after stretching, the film adhesion, antistatic properties, slipperiness, light shielding properties, and the like can be improved. Furthermore, for example, the above polyester resin can be used for the core layer, and a co-extrusion method or the like can be formed, for example, by providing a copolymer polyester resin layer having a crystallinity lower than that of the polyester resin on the surface layer.

[Physical characteristics of the film of the present invention]
The thickness of the film of this invention can be suitably selected according to a use, and it exists in the range of 1-600 micrometers normally. For example, in the case of packaging applications such as foods, beverages, and pharmaceuticals, the thickness is 5 to 400 μm, preferably 5 to 200 μm. When used as a label for a bottle such as a polyester bottle or a glass bottle or other plastic containers, a thickness of 20 to 100 μm, preferably 20 to 80 μm, more preferably 20 to 60 μm is suitable. It is.

  The shrinkage stress in the main shrinkage direction of the film of the present invention varies slightly depending on the thickness of the film. For example, when the film thickness is 50 μm, the maximum value is usually 12 MPa or less at 80 ° C., preferably Is 11 MPa or less, more preferably 10 MPa or less. If the shrinkage stress is 10MPa or less, wrinkles or bends will occur when mounting on a square PET bottle or a plastic container with a catching part, or when using a heating method with strong directivity such as hot air or far infrared rays. It is preferable because it is difficult.

The film of the present invention has a tensile modulus in the flow direction (MD) of 1,000 to 3,000 MPa, preferably 1,300 to 2,700 MPa, more preferably 1,800 to 2,200 MPa, and is orthogonal to MD. The tensile modulus in the direction (TD) is 4,000 to 7,000 MPa, preferably 4,400 to 6,000 MPa, and more preferably 4,800 to 5,500 MPa. Tensile modulus was measured by collecting test pieces with a width of 5 mm and a length of 70 mm on MD and TD, respectively, and setting the test pieces in a tensile tester installed in a temperature-controlled room at 23 ° C. and 50 RH% with a chuck interval of 50 mm. -A strain curve is calculated | required by the tensile test speed | rate of 5 mm / min, and a tensile elasticity modulus can be calculated | required from the following formula in the linear part immediately after a test start.
Tensile modulus = Stress difference due to the original average cross-sectional area between two points on a straight line / Strain difference between the same two points

  The film of the present invention has a right-angled tear strength measured in accordance with JIS K7128-3 of 100 to 400 N / mm in MD, preferably 150 to 350 N / mm, more preferably 200 to 300 N / mm, and 200 in TD. It is -500 N / mm, Preferably it is 300-450 N / mm, More preferably, it is 350-410 N / mm.

  The breaking resistance of the film of the present invention is evaluated by tensile elongation. In a tensile test under an environment of 0 ° C., particularly for label use, the elongation is 100% or more in the film take-off (flow) direction (MD), preferably It is 200% or more, more preferably 300% or more.

  The transparency of the film of the present invention is indicated by a haze value measured in accordance with JIS K7105. The haze value is preferably 10% or less, more preferably 7% or less, and 5% or less. Is more preferable. If the haze value is 10% or less, good transparency can be obtained, and beautiful printing or the like becomes possible.

The shrink finish of the film of the present invention is, for example, obtained by cutting a sample piece of a predetermined size on MD and TD to produce a bag-like label and attaching it to a container, and then passing a steam shrinker at 75 ° C. for 5 seconds. It can be expressed by the degree of finish after. In the film of the present invention, the number of wrinkles having a width of 5 mm or less and a length of 50 mm or less per 100 cm ² is 3 or less, preferably 2 or less, more preferably 1 or less, and most preferably 0.

  The change with time of elongation of the film of the present invention is that a film of a predetermined size left in a 30 ° C. gear oven for 30 days is 50% or more of the original film length even when the TD is 20 mm between chucks and the tensile speed is 200 mm / min. It can be represented by the number that extends (ie, beyond the yield point). For example, after storage at 30 ° C. for 30 days, a test piece cut out at 15 mm in the main shrinkage direction of the film and 50 to 150 mm, preferably 50 to 100 mm, more preferably 100 mm in the direction perpendicular to the main shrinkage direction, is the distance between chucks When a tensile test is performed under the conditions of 20 mm, 23 ° C., 50% RH, and a tensile speed of 200 mm / min, the number of films that extend by 50% or more of the original film length is preferably 80% or more of all test pieces, and 90% or more. Is more preferable, and 100% is most preferable.

  The seal strength of the film of the present invention is 3 N / 15 mm or more and 5 N / 15 mm or more using the measurement method described in the method described herein (23 ° C., 50% RH environment, test speed 200 mm / min). It is preferable that it is 8 N / 15 mm or more. If the sealing strength of the film is 3 N / 15 mm or more, it is preferable that the label is adhered without being peeled off when it is sealed.

[Heat-shrinkable multilayer polyester film]
The film of the present invention can be formed into a multilayer film by laminating other layers made of heterogeneous materials or homogeneous materials. The multilayer film may include at least one layer of the film of the present invention. For example, in addition to the film of the present invention, two or three types, three types or five layers, or four types or seven layers made of one kind or two kinds of heterogeneous materials, It can be composed of a plurality of layers depending on the application. Among them, a 2 type 3 layer or 3 type 5 layer using the film of the present invention as the intermediate layer is preferable. For example, the front and back layers are preferably layers made of a resin excellent in printing and sealing properties, and the film of the present invention is preferably used for the intermediate layer in order to impart shrinkage characteristics.

  The multilayer film of the present invention is preferably a resin having low crystallinity as a resin used for the front and back layers, for example, containing 25 mol% or less of 1,4-butanediol as a diol component and 25 mol of 1,4-cyclohexadimethanol. It is desirable to use a resin containing at least%.

  The thickness ratio of the multilayer film of the present invention is, for example, in the case of 2 types and 3 layers, the thickness ratio in the range of front and back layers: intermediate layer: front and back layers = 1: 2: 1 to 1: 10: 1. it can. In the case of 3 types and 5 layers, [front and back layers: adhesive layer]: intermediate layer: [adhesive layer: front and back layers] = [1]: 2: [1] to [1]: 10: [1] thickness The thickness ratio of [front and back layer: adhesive layer] can be in the range of 1: 1 to 5: 1.

  In the multilayer film of the present invention, the thickness of the entire film can be appropriately selected according to the use, and is usually in the range of 1 to 600 μm. For example, in the case of packaging applications such as foods, beverages, and pharmaceuticals, the thickness is 5 to 400 μm, preferably 5 to 200 μm. When used as a label for a bottle such as a polyester bottle or glass bottle or other plastic container, the thickness is in the range of 20-100 μm, preferably 20-80 μm, more preferably in the range of 20-60 μm. It is.

[Molded products, containers]
The resin composition of the present invention is a variety of molded products by a conventional molding method of thermoplastic resins, for example, films and sheets obtained by extrusion molding, stretched films obtained by subjecting them to stretching, or vacuum molding and pressure molding of them. Molded into various molded products (for example, molded products having a cylindrical shape, a quadrangular prism, and a body with a constricted body part) by trays and containers subjected to thermoforming, etc., injection molding, hollow molding, compression molding, etc., or They are molded into a molded product having a laminated structure with other materials, and are particularly suitably used as packaging materials. Among them, heat-shrinkable film as a material for packaging, binding, covering, etc. for label materials and mouth seal materials for covering outer peripheral surfaces of various food and beverage bottles, etc. It can be suitably used as a heat-shrink label of a container having an unbalanced shape having both a part and a thick part of the trunk.

  Examples of the present invention are shown below, but the present invention is not limited to the following examples unless it exceeds the gist.

<Measurement method>
(1) Measurement of heat shrinkage rate of film The film is cut into a size of 150 mm in the flow (drawing) direction (stretching direction: MD) and 10 mm in the vertical direction (TD), and a 100 mm mark is put on the sample piece. The amount of shrinkage in each direction was immersed in a hot water bath at 70 ° C. and 80 ° C. for 10 seconds, then immediately immersed in cold water at 20 ° C., and obtained using the following formula.
Thermal contraction rate = {(100-L) / 100} × 100 (%)
L: Distance between marked lines after contraction (mm)

(2) Measurement of elongation of film over time A film left for 30 days in a gear oven at 30 ° C. was carefully cut out with a feather blade in MD15 mm and TD100 mm, respectively, and 10 test pieces were produced. Next, the number of the test pieces that were extended to 50% or more under the conditions of 20 mm between chucks and a tensile speed of 200 mm / min was measured using TM-20 manufactured by Intesco. At this time, 8 to 10 were evaluated as O, 5 to 7 as Δ, and 4 or less as X.

(3) Measurement of shrinkage finish of film A sample piece of TD 240 mm and MD 60 mm was cut out, and a bag-like label having a folding diameter of 105 mm was prepared using an impulse sealer. This label was attached to the zenith of a Morinaga Caldas milk bottle, and the finish after passing through a steam shrinker manufactured by KE SYSTEM Co., Ltd. set at a temperature of 75 ° C. for 5 seconds was measured. The number of specimens was 10 and the number of wrinkles generated in each specimen was measured. At this time, all the samples with no shrinkage and no wrinkles, which were cleanly finished, were evaluated as ◯, the samples containing some wrinkles were evaluated as △, and most of the samples were wrinkled or insufficiently contracted as ×. .

The composition analysis of the polyester resin used in each example and comparative example was performed by the following method.
A polyester resin solution sample was analyzed by monitoring ¹ H with a nuclear magnetic resonance apparatus (NMR), with respect to the dicarboxylic acid component, mol% relative to the total dicarboxylic acid component, and with respect to the diol component, mol% relative to the total diol component, Furthermore, content (mass%) with respect to the polyester resin of a polyalkylene glycol component was calculated | required.

<Preparation of polyethylene terephthalate copolymer>
(1) Polyethylene terephthalate copolymer 1 (PET1)
“EMBRACE Copolyester” manufactured by Eastman Chemical Co. was used. The polyester resin was subjected to composition analysis by the method described above. As a result, the dicarboxylic acid component was terephthalic acid (hereinafter referred to as “TPA”), and the diol component was ethylene glycol (hereinafter “ EG ”) 72 mol%, 1,4-cyclohexanedimethanol (hereinafter“ CHDM ”) 20 mol%, and diethylene glycol (hereinafter“ DEG ”) 8 mol%.

(2) Polyethylene terephthalate copolymer 2 (PET2)
“EASTAR PETG Copolyester 6763” manufactured by Eastman Chemical Co. was used. The polyester resin was subjected to composition analysis by the above-described method. As a result, the dicarboxylic acid component was TPA, and the diol component was 67 mol% EG, 30 mol% CHDM , and 3 mol% DEG based on the total diol. It was.

(3) Polyethylene terephthalate copolymer 3 (PET3)
TPA, EG and DEG are put into a batch polymerization vessel equipped with a reflux tower, a stirrer and a pelletizer, heated to 200-250 ° C. and depressurized, and the esterification reaction is carried out while distilling off the by-product water. Then, PET3 having a dicarboxylic acid component of 100 mol% of TPA, a diol component of 80 mol% of EG, and 20 mol% of DEG was prepared. After the melt polycondensation, the obtained polyester resin was drawn out into water as a strand and then cut into a pellet.

<Preparation of polybutylene terephthalate copolymer>
(1) Polybutylene terephthalate copolymer 1 (PBT1)
The dicarboxylic acid component is TPA, the diol component is 1,4-butanediol (hereinafter referred to as “BD”), isophthalic acid (hereinafter referred to as “IPA”) as a copolymer component is 5 mol% in the total dicarboxylic acid component, and A PBT containing 2.5 mol% of polytetramethylene glycol (number average molecular weight 1,000, hereinafter referred to as “PTMG”) in the total diol component was prepared by the same method as PET 3, and the obtained PBT was coated with a lubricant. As a result, 0.1 wt% of amorphous silica having an average particle size of 2.4 μm was added to prepare PBT1.

(2) Polybutylene terephthalate copolymer 2 (PBT2)
Dicarboxylic acid component is TPA, diol component is BD, IPA as copolymerization component is 10 mol% in all dicarboxylic acid components, and PTMG (number average molecular weight 1,000) is 5.0 mol% in all diol components A PBT to be prepared was prepared in the same manner as PET3, and 0.1 mass% of amorphous silica having an average particle size of 2.4 μm was added as a lubricant to the obtained PBT to prepare PBT2.

(3) Polybutylene terephthalate copolymer 3 (PBT3)
“Novaduran 5008” manufactured by Mitsubishi Engineering Plastics was used. The PBT was subjected to composition analysis by the above-described method. As a result, the dicarboxylic acid component was 100 mol% of TPA and the diol component was 100 mol% of BD. PBT3 was prepared by adding 0.1% by mass of amorphous silica having an average particle size of 2.4 μm as a lubricant to the PBT.

(4) Polybutylene terephthalate copolymer 4 (PBT4)
PBT containing dicarboxylic acid component as TPA and diol component as BD, and containing 15 mol% of IPA as copolymerization component in the total dicarboxylic acid was prepared by the same method as PET3. PBT4 was prepared by adding 0.1% by mass of 2.4 μm amorphous silica.

(5) Polybutylene terephthalate copolymer 5 (PBT5)
The dicarboxylic acid component is TPA, the diol component is BD, and PBT containing 8 mol% of PTMG (number average molecular weight 1,000) as the copolymer component in the total diol component is prepared by the same method as PET3. PBT5 was prepared by adding 0.1% by mass of amorphous silica having an average particle size of 2.4 μm as a lubricant to the PBT.

(6) Polybutylene terephthalate copolymer 6 (PBT6)
A PBT having a dicarboxylic acid component of TPA and a diol component of BD and containing 5 mol% of PTMG (number average molecular weight 300) as a copolymerization component in the total diol component by the same method as PET3 was obtained. PBT6 was prepared by adding 0.1% by mass of amorphous silica having an average particle size of 2.4 μm as a lubricant.

(7) Polybutylene terephthalate copolymer 7 (PBT7)
The dicarboxylic acid component is TPA, the diol component is BD, and a PBT containing 5 mol% of PTMG (number average molecular weight 3,000) as a copolymerization component in the total diol component is prepared by the same method as PET3. PBT7 was prepared by adding 0.1% by mass of amorphous silica having an average particle size of 2.4 μm as a lubricant to the PBT.

<Preparation of polyester resin composition pellets>
The components (A) and (B) shown in Table 1 are supplied to a twin screw extruder (L / D30, “TEM35” manufactured by Toshiba Machine Co., Ltd.), screw rotation number 150 rpm, temperature 260 ° C., 1 × 10 ² Pa. Polyester resin composition pellets were produced by melt-kneading under reduced pressure, extruding into strands, cooling in a water bath, and cutting with a pelletizer.

Example 1
The produced resin composition pellets (PET 1: 85% by mass, PBT 1: 15% by mass) are cooled by a TEM 58 mm extruder (manufactured by TOSHIBA MACHINE) with a vacuum vent from a 200 mm wide T die die at a time discharge rate of 8 kg. The sheet was extruded at 270 ° C. to obtain a sheet having a width of 150 mm and a thickness of 0.2 mm. Next, the sheet was stretched 5 times in the vertical direction with respect to the casting extrusion direction at a stretching temperature of 80 ° C. and a stretching speed of 3000% / min using a standard film stretcher (manufactured by TM Long). A heat-shrinkable film having a thickness of 40 μm was obtained.
The shrinkage ratio after treating the obtained heat-shrinkable film in warm water at 70 ° C. and 80 ° C. for 10 seconds, the shrinkage finish at 75 ° C., and the deterioration with time after standing at 30 ° C. for 30 days were measured. The results are shown in Table 1.

(Examples 2 and 3)
By the same method as in Example 1, heat-shrinkable films were prepared at the resin composition pellets having the composition shown in Table 1 and the stretching temperature, and the shrinkage rate, shrinkage finish, and elongation with time were measured. The results are shown in Table 1.

Example 4
For the center layer, resin composition pellets containing 85% by mass of PET1 and 15% by mass of PBT1 were used. Further, resin composition pellets containing 85% by mass of PET2 and 15% by mass of PBT1 were used for both outer layers. The resin composition pellets in the center layer are ejected by a TEM 58 mm extruder (manufactured by Toshiba Machine) at a time discharge rate of 8 kg. A three-layer structure in which a vacuum vent is pulled from a seed three-layer T die die onto a cooling roll at 270 ° C., the width is 150 mm, the thickness of both outer layers is 0.025 mm, and the thickness of the center layer is 0.15 mm. An unstretched sheet was obtained. Next, the sheet was stretched in the same manner as in Example 1 to obtain a laminated heat-shrinkable film having a thickness of 40 μm (both outer layers had a thickness of 5 μm and a center layer had a thickness of 30 μm).
The shrinkage rate, shrinkage finish, and elongation aging of the obtained heat-shrinkable film were measured. The results are shown in Table 1.

(Comparative Examples 1-9)
In the same manner as in Example 1, heat-shrinkable films were prepared with resin composition pellets having the composition shown in Table 1 as Comparative Examples 1 to 9 and the stretching temperature, and the shrinkage rate, shrinkage finish, and elongation with time were measured. . The results are shown in Table 1.

(Comparative Example 10)
In the same manner as in Example 4, a heat-shrinkable film was produced at the resin composition pellets having the composition shown in Table 1 and the stretching temperature, and the shrinkage rate, shrinkage finish, and elongation with time were measured. The results are shown in Table 1.

From Table 1, the film produced using the resin composition of the present invention was treated at 70 ° C. for 10 seconds both in the case of a single layer (Examples 1 to 3) and in the case of a multilayer (Example 4). The shrinkage rate of the film was 20% or more, and the shrinkage rate of the film after treatment at 80 ° C. for 10 seconds was 40% or more. Furthermore, it can be seen that the film produced using the resin composition of the present invention exhibits excellent shrinkage finish properties at low temperatures and can suppress the embrittlement of the film over time.
On the other hand, when the content of PET and PBT is outside the scope of the present invention (Comparative Examples 1 and 2), the content of IPA, CHDM, EG, DEG, and PTMG constituting the copolymer is When the number average molecular weight of the single layer (Comparative Examples 3 to 7) and the multilayer (Comparative Example 10) or PTMG outside the range is outside the range of 500 to 2000 (Comparative Examples 8 and 9), both As in the case of the film of the present invention, a film satisfying all of the shrinkage rate, the low-temperature finish and the deterioration with time was not obtained.
Accordingly, the content of the polyethylene terephthalate copolymer and the polybutylene terephthalate copolymer is adjusted to a predetermined range, and the content of IPA, CHDM, EG, DEG and PTMG constituting the copolymer is set to a predetermined range. The heat-shrinkable film using the prepared polyester resin composition can be used even with shrinkers at low temperatures, has very little wrinkle, distortion, shrinkage spots, etc. It can be seen that the film is difficult to embrittle.

The resin composition of the present invention can be used as various molded articles and containers obtained by a thermoplastic resin molding method. Among them, the film using the resin composition of the present invention is sufficiently compatible with shrinkers at low temperatures, has very little wrinkle, distortion, shrinkage spots, etc. at the time of shrinkage, excellent in low temperature shrinkage characteristics, over time. Since it is a film that is not easily embrittled, it can be used for various molded products and containers, and can be suitably used particularly as a heat-shrinkable film.

Claims (12)

A polyester resin composition comprising the following components (A) and (B):
(A) It contains at least terephthalic acid as a dicarboxylic acid component, ethylene glycol, 1,4-cyclohexanedimethanol and diethylene glycol as diol components, and 1,4-cyclohexanedimethanol is 15 mol% or more in 100 mol% of all diol components. Polyethylene terephthalate copolymer containing less than 25 mol% and containing 5 mol% or more and less than 15 mol% of diethylene glycol: 70 to 90 mass%
(B) terephthalic acid and isophthalic acid as dicarboxylic acid components, 1,4-butanediol and polytetramethylene glycol as diol components, and 2 to 8 mol% isophthalic acid in 100 mol% of all dicarboxylic acid components, Polybutylene terephthalate copolymer containing 1 to 5 mol% of polytetramethylene glycol in 100 mol% of all diol components: 10 to 30% by mass   The resin composition according to claim 1, wherein the polytetramethylene glycol has a number average molecular weight of 500 to 2,000.   The polyester resin composition according to claim 1 or 2, which is used for a heat-shrinkable polyester film.   The heat-shrinkable polyester film formed with the resin composition as described in any one of Claims 1-3.   The shrinkage rate in the main film shrinkage direction after treatment for 10 seconds in 70 ° C. warm water is 20% or more and less than 40%, and the shrinkage rate in the film shrinkage direction after treatment for 10 seconds in warm water at 80 ° C. The heat-shrinkable polyester film according to claim 4, which is 40 to 70%.   The difference between the shrinkage ratio in the main film shrinkage direction after being treated for 10 seconds in warm water at 70 ° C and the shrinkage ratio in the film shrinkage direction for 10 seconds in hot water at 80 ° C is 40% or less. The heat-shrinkable polyester film according to 4 or 5.   After storage at 30 ° C. for 30 days, a test piece cut at 15 mm in the main shrinkage direction of the film and 50 to 150 mm in a direction perpendicular to the main shrinkage direction is a distance between chucks of 20 mm, a temperature of 23 ° C., and a tensile speed of 200 mm / min. The number of test pieces that extend by 50% or more of the original film length when the tensile test is performed below is 80% or more of the total number of test pieces. Polyester film.   The heat-shrinkable polyester film according to any one of claims 4 to 7, obtained by stretching 4.0 to 6.0 times in the main shrink direction of the film.   A heat-shrinkable multilayer polyester film comprising at least one heat-shrinkable polyester film according to any one of claims 4 to 8.   The polyester-based resin composition according to any one of claims 1 to 3, the heat-shrinkable polyester film according to any one of claims 4 to 8, or the heat-shrinkable laminate according to claim 9. Molded product formed using a film.   The molded article according to claim 10, wherein the molded article is a label for a food container. A container equipped with the molded product according to claim 10 or 11.