JPH0825477A - Heat-shrinkable polyester film - Google Patents

Abstract

PURPOSE:To improve shrinkability at low temp. and to eliminate the generation of shrink irregularity while enhancing close adhesiveness after shrinkage by using a polyester resin consisting of specific components and characterized by that a shrinkage factor is within a predetermined range in predetermined hot water. CONSTITUTION:A heat-shrinkable polyester film is composed of a polyester resin consisting of an acid component based on aromatic carboxylic acid such as terephthalic acid or isophthalic acid or an ester forming derivative thereof and an alcohol component. The shrinkage factor of this heat-shrinkable polyester film is 5% or more when the film is immersed in hot water at 60 deg.C for 1min under a non-weighting condition and 30% or more when the film is immersed in hot water at 80 deg.C for 1min under a non-weighing condition. Further, a shrinkage factor (S70) obtained when the film is shrunk in hot water at 70 deg.C for 1min, a shrinkage factor (S80) obtained when the film is shrunk in hot water 80 deg.C for 1min and a shrinkage factor (S90) obtained when the film is shrank in hot water at 90 deg.C for l min satisfy S90-S8>S80-S70.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-shrinkable polyester film used for various packaging materials, and more specifically, it has excellent shrinkage properties at low temperatures, and has no shrinkage unevenness and adhesion after shrinkage. The present invention relates to an excellent heat-shrinkable polyester film.

[0002]

2. Description of the Related Art Heat-shrinkable plastic films are used for marking and protecting containers, fishing rods, condensers, rod-shaped fluorescent lamps, etc.
It is used for bundling, improving the added value of products, etc., and is also used for the integrated packaging of books and notebooks and the close packaging.
At present, it is expected to develop various applications in many other fields by utilizing the shrinkability and shrinkage stress of the heat-shrinkable film.

Conventionally, as materials for heat-shrinkable films,
Resins such as polyvinyl chloride, polystyrene, and polyolefin have been used. However, such resins have drawbacks in heat resistance, weather resistance, chemical resistance and the like. For example, although polyvinyl chloride film can be used as a heat-shrinkable film having various shrinkage characteristics, fish eyes are likely to occur frequently, and the product printed with this film has a poor aesthetic appearance and a reduced commercial value. It was easy to become what I did. Also, in order to obtain a heat-shrinkable film without fish eyes, excessive quality control is required,
There was a problem that the film production cost increased remarkably. Furthermore, polyvinyl chloride causes pollution problems when incinerated at the time of disposal, and additives such as plasticizers in the polyvinyl chloride resin bleed out over time, causing dirt and other contamination, and It was not preferable in terms of sex.

On the other hand, a heat-shrinkable film obtained from polystyrene has a good finish after shrinkage, but has a low solvent resistance, so that a special ink must be used for printing, and even at room temperature. It had to be stored in a cool place due to spontaneous shrinkage. In addition, there is a big problem in the disposal because it needs to be incinerated at a high temperature and a large amount of black smoke and a strange odor are generated during the incineration. As a material capable of solving these problems, polyester film is highly expected, and its usage amount has been remarkably increasing.

[0005]

However, the conventional heat-shrinkable polyester film has not been sufficiently satisfactory in its heat-shrinkability. In particular, shrinkage unevenness is likely to occur during shrinkage, and when coating and shrinking on containers such as PET bottles, polyethylene bottles, glass bottles, the characters and patterns printed on the film cannot be reproduced well, and the film can be sufficiently adhered to the container. There were problems such as not being there.

Further, it is inferior in shrinkability at low temperature as compared with polystyrene film or the like, and must be shrunk at high temperature in order to obtain a required shrinkage amount, which causes deformation and whitening of bottles and the like. He also had points. In particular, when used as a label for a polyethylene bottle, the polyethylene bottle itself is inferior in heat resistance to a PET bottle and the like, and therefore shrinking work must be performed at a lower temperature, for example, about 70 ° C. A heat-shrinkable film having excellent characteristics is required.

In response to such a demand, Japanese Patent Application No. 4-11
As described in Japanese Patent Application No. 0963 and Japanese Patent Application No. 4-110964, a heat shrinkable polyester having a shrinkage initiation temperature of 50 ° C. or less by using a polyester resin copolymerized with a specific copolymerization component. A film, a heat-shrinkable polyester film in which uneven shrinkage is less likely to occur by controlling the shrinkage speed, and the like have been proposed. However, even in such a heat-shrinkable polyester film, the problem of shrinkage unevenness has not been completely solved. For example, once shrinkage unevenness occurs during shrinkage, the generated shrinkage unevenness is fixed and shrinkage unevenness is fixed. It had a problem that it could not be removed. Further, the adhesiveness of the heat-shrinkable polyester film to the container has not been sufficiently satisfactory. An object of the present invention is to provide a heat-shrinkable polyester film which is excellent in shrinkage characteristics at low temperature, has no uneven shrinkage and does not remain, and has excellent adhesion after shrinkage.

[0008]

The inventors of the present invention have arrived at the present invention as a result of earnestly examining the heat shrinkage behavior of a polyester film in view of such circumstances.
That is, the heat-shrinkable polyester film of the present invention,
A polyester resin composed of an acid component containing an aromatic dicarboxylic acid or its ester-forming derivative as a main component and an alcohol component, and contracted in warm water at 60 ° C. for 1 minute (S ₆₀ ), in warm water at 70 ° C. The contraction rate after contracting for 1 minute (S ₇₀ ), the contraction rate after contracting for 1 minute in warm water at 80 ° C. (S ₈₀ ) and the contraction rate for contracting for 1 minute in warm water at 90 ° C. (S ₉₀ ) are as follows. It is characterized by satisfying the expressions (1) to (3).

[0009]

[Equation 4] S ₆₀ ≧ 5% (1)

[0010]

[Equation 5] S ₈₀ ≧ 30% (2)

[0011]

## EQU00006 ## S ₉₀ -S ₈₀ > S ₈₀ -S ₇₀ (3) The heat-shrinkable polyester film of the present invention shrinks when it is dipped in warm water at 60 ° C. for 1 minute without weighting to shrink. Rate is 5
% Or more, and it is necessary that the shrinkage percentage when immersed in warm water at 80 ° C. for 1 minute without weighting and shrinking is 30% or more. When the shrinkage ratio at 60 ° C is less than 5%,
Adhesion of the film to the container is not sufficient, and the heating temperature in the shrinking process must be raised.If the heating temperature in the shrinking process is raised, the container such as a bottle may be deformed or whitened, and This is because the shrinkable film causes rapid shrinkage, which causes uneven shrinkage. Considering the occurrence of uneven shrinkage due to abrupt shrinkage when the film shrinks, the shrinkage ratio at 60 ° C. is preferably in the range of 10 to 30%. Further, if the shrinkage ratio at 80 ° C is less than 30%, a sufficient shrinkage amount cannot be obtained, and the adhesion of the film to the container becomes insufficient, so that the container having a particularly complicated shape can be completely covered. It will be difficult. Considering the occurrence of uneven shrinkage due to rapid shrinkage when the film shrinks,
It is preferable that the shrinkage rate at 40C is in the range of 40 to 60%. Further, in the present invention, the shrinkage initiation temperature is 50 ° C.
The following is preferable in order to obtain excellent low-temperature shrinkage properties, and more preferably at least 1% at 50 ° C., and more preferably 2% or more.

The heat-shrinkable polyester film of the present invention has a shrinkage ratio (S
₇₀ ), the shrinkage rate (S ₈₀ ) after shrinking in hot water at 80 ° C for 1 minute, and the shrinkage rate (S ₉₀ ) after shrinking in warm water at 90 ° C for 1 minute satisfy the following equation (3). It is necessary. That is, the heat-shrinkable polyester film is 70
Shrinkage once converges in the temperature range of ~ 80 ° C,
By exhibiting shrinkage behavior such that shrinkage becomes large again in the temperature range of 90 ° C., even when shrinkage unevenness occurs in the temperature range up to 80 ° C., the generated shrinkage unevenness can be alleviated in this temperature range, and the shrinkage unevenness can be reduced. It is possible to perform an excellent shrinkage-free coating, and also to achieve perfect adhesion to a container or the like.

[0013]

## EQU00007 ## S ₉₀ -S ₈₀ > S ₈₀ -S ₇₀ (3) Further, in the present invention, the shrinkage ratio (S ₈₀ ) obtained by shrinking in hot water of 80 ° C. for 1 minute and the hot water of 90 ° C. It is preferable that the difference from the shrinkage rate (S ₉₀ ) obtained by shrinking for 1 minute is 3% or more. This is because the difference in shrinkage ratio in this relatively high temperature range is 3% or more, so that even when shrinkage unevenness occurs in the temperature range up to 80 ° C., the generated shrinkage unevenness occurs in this temperature range. This is because it is possible to relax and perform an excellent shrink coating without shrinkage unevenness. Considering the occurrence of shrinkage unevenness due to abrupt shrinkage, the difference in shrinkage ratio is 5
It is in the range of 15%.

The polyester resin used in the heat-shrinkable polyester film of the present invention is composed of an acid component and an alcohol component containing an aromatic dicarboxylic acid or its ester-forming derivative as a main component, and preferably terephthalic acid or its component. Consists of an acid component whose main component is an ester-forming derivative and an alcohol component whose main component is ethylene glycol. The ratio of acid components other than terephthalic acid in the total acid component and the ratio of alcohol components other than ethylene glycol in the total alcohol component. Is 10 to 50 mol%.
Moreover, as the polyester resin, a mixture of two or more polyester resins can be used.

If the sum of the ratio of the acid components other than terephthalic acid in the total acid components and the ratio of the alcohol components other than ethylene glycol in the total alcohol components is less than 10 mol%, sufficient solvent adhesiveness tends not to be obtained. On the contrary, if it exceeds 50 mol%, the solvent resistance of the film itself tends to be poor, and a resin capable of forming a film tends not to be obtained, and the range of 20 to 40 mol% is more preferable.

In the present invention, examples of the aromatic dicarboxylic acid constituting the polyester resin include terephthalic acid, isophthalic acid, naphthalene-1,4- or -2,6-dicarboxylic acid. The aromatic dicarboxylic acid or its ester-forming derivative is preferably contained in the acid component of the polyester resin in an amount of 80 mol% or more, and more preferably 85 mol% or more. this is,
When the aromatic dicarboxylic acid or its ester-forming derivative is less than 80 mol%, the mechanical strength of the formed polyester film tends to be lowered. From the viewpoint of the mechanical strength of the film, the proportion of terephthalic acid in all the acid components is preferably 60 mol% or more, more preferably 70 mol% or more.

Further, in the present invention, for the purpose of enhancing the effect of the present invention and increasing the amount of heat shrinkage, an aliphatic dicarboxylic acid or its ester-forming derivative is contained in the polyester resin in an amount of less than 20 mol%, It may be contained preferably in the range of less than 15 mol%. This is because if the content of these aliphatic dicarboxylic acid components is 20 mol% or more, the mechanical strength of the polyester film may decrease. Examples of the aliphatic dicarboxylic acid that can be used in the present invention include glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid and succinic acid.

In the present invention, the alcohol component constituting the polyester resin contains at least one selected from ethylene glycol, butanediol, cyclohexanedimethanol and an ethylene oxide adduct of a bisphenol compound or its derivative as a main component. It is preferable that 80 mol% or more of these diol components is contained in the total alcohol components. Among them, those containing 50 mol% or more of ethylene glycol in all alcohol components are preferable, and 70 mol% or more is more preferable. This is because when the content of ethylene glycol is less than 50 mol%, the polymerization reactivity tends to decrease during the production of the resin, and the resin having the desired degree of polymerization may not be obtained. is there.

In addition to the above-mentioned diol component, other alcohol components such as propylene glycol, triethylene glycol, diethylene glycol, neopentyl glycol, polyethylene glycol, polytetramethylene glycol, etc. may be used within a range that does not impair the effects of the present invention, for example. Two
It can also be used in the range of 0 mol% or less.

In the present invention, rapid contraction is suppressed,
For the purpose of further reducing shrinkage unevenness, a trivalent or higher polyvalent carboxylic acid or polyhydric alcohol may be used. Specific examples of the trivalent or higher polycarboxylic acid or polyhydric alcohol include polycarboxylic acids such as trimellitic acid, pyromellitic acid and their anhydrides, trimethylolpropane, trimethylolethane, glycerin, diglycerin, Examples include polyhydric alcohols such as pentaerythritol. Of these, trimethylolpropane, trimellitic acid, and pentaerythritol are preferable from the viewpoints of thermal stability during film formation and reactivity during polycondensation.

The polyester resin of the present invention can be produced by a known direct polymerization method or transesterification method,
The degree of polymerization is not particularly limited, but the intrinsic viscosity (measured at 25 ° C. in a mixed solution of phenol / tetrachloroethane by weight) is 0.5 because of the moldability of the raw film.
The thing of -1.2 is preferable.

The resulting polyester resin is molded into a heat-shrinkable polyester film by the following method, for example. First, after drying the polyester resin, melt it,
Melt extrusion is performed from a die, and a raw film is formed by a casting method or a calendar method. Next, this raw film was set to 3 from the glass transition temperature (Tg) of the polyester resin.
1.5 to 5.0 times in the longitudinal or transverse direction, preferably 1.0 at a temperature higher than ℃, preferably higher than 5 ℃
The film is stretched to 4.8 times to give a high shrinkage rate to the film. Further, if necessary, it is stretched 1.0 to 1.8 times, preferably 1.0 to 1.5 times in the direction perpendicular to the stretching direction. This is effective in improving the tensile strength of the film and preventing the shrinkage in the stretching direction from shrinking more than necessary.

The stretching of the film is carried out by a method such as simultaneous biaxial stretching, sequential biaxial stretching, uniaxial stretching, etc. Either longitudinal stretching or transverse stretching may be performed first. The stretched heat-shrinkable polyester film can be used as a product as it is, but may be heat-treated at a temperature of 50 to 150 ° C. for several seconds to several tens seconds from the viewpoint of dimensional stability and the like. By performing such heat treatment,
The polyester film of the present invention can exhibit desirable properties such as adjustment of the shrinkage ratio in the shrinking direction, reduction of time-dependent shrinkage of the unshrinked film during storage, and reduction of shrinkage unevenness.

The thickness of the heat-shrinkable polyester film of the present invention is not particularly limited, but it is 1 to 600 μm.
Those in the range of are practically used. 6 to 380 μm for packaging applications, especially packaging of foods, beverages, pharmaceuticals, etc.
Those in the range of are used. When used for labels such as PET bottles, polyethylene bottles and glass bottles, those having a range of 20 to 70 μm are used.

In the present invention, in order to impart more specific performance, various conventionally known processing treatments and suitable additives can be added. Examples of processing include ultraviolet rays and α
Irradiation with rays, β rays, γ rays or electron rays, corona treatment,
Examples thereof include plasma irradiation treatment, flame treatment and the like, coating of resin such as vinylidene chloride, polyvinyl alcohol, polyamide and polyolefin, laminate, vapor deposition of metal and the like. Examples of additives include polyamide, polyolefin, polymethylmethacrylate, resins such as polycarbonate, silica, talc, kaolin, inorganic particles such as calcium carbonate, titanium oxide, pigments such as carbon black, ultraviolet absorbers, release agents, and the like. Flame retardants and the like can be mentioned.

[0026]

EXAMPLES The present invention will be specifically described below with reference to examples. The shrinkage ratio in the examples is 150 m in the stretching direction.
m, a polyester film cut out in a size of 20 mm in the direction perpendicular to it is provided with marking lines at intervals of 100 mm.
When immersed in each warm water of 0 to 90 ° C. for 1 minute without load, in the stretching direction of the film, the length before shrinkage (L)
The length after shrinkage (L ') was measured and determined by the following formula.

[0027]

[Equation 8] Shrinkage (%) = {(L−L ′) / L} × 100 Heat unevenness is 150 mm in the stretching direction and 2 in the direction perpendicular to the stretching direction.
A polyester film cut into a size of 0 mm
After heat-shrinking for 1 minute with no load in warm water at 80 ° C,
The appearance of shrinkage unevenness on the film was evaluated in three stages: ◯: Almost no shrinkage unevenness was observed. Δ: Some shrinkage unevenness was found. ×: Shrinkage unevenness was noticeable.

Adhesion was determined by mounting a shrink film on the body of a 1.5-liter PET bottle and heating it in hot air at 90 ° C. for 10 seconds to shrink it. Even if it is attached so that it does not move △: It is completely attached to the container, but it moves slightly when touched with the hand ×: It is not completely attached to the container and it shifts when touched by hand It was evaluated according to the standard.

Example 1 80 mol parts of terephthalic acid, 15 mol parts of isophthalic acid, 5 mol parts of adipic acid, 140 mol parts of ethylene glycol,
10 mol parts of cyclohexanedimethanol was placed in a reaction vessel, and the ester reaction was sufficiently performed under nitrogen pressure. Next, trimethyl phosphate as a stabilizer was added to the total acid component in an amount of 50 ppm, antimony trioxide was added as a polymerization catalyst in an amount of 300 ppm, and titanium tetrabutoxide was added to the total acid component in an amount of 500 ppm. While maintaining the temperature at 280 ° C., a polycondensation reaction was performed for 3 hours under a reduced pressure of 5 mmHg or less to obtain a polyester resin.
The obtained polyester resin was dried and then melt-extruded from a T die at a resin temperature of 270 ° C. to prepare a raw film. This raw film was uniaxially stretched 4.5 times in the stretching direction (TD direction) at 80 ° C. to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 1 shows the resin composition of the obtained film, the measurement result of the shrinkage ratio, and the evaluation result of the shrinkage unevenness.

Example 2 85 mol parts of terephthalic acid, 10 mol parts of isophthalic acid, 5 mol parts of adipic acid, 140 mol parts of ethylene glycol,
15 mol parts of cyclohexanedimethanol was placed in a reaction vessel, and the ester reaction was sufficiently performed under nitrogen pressure. Next, 50 ppm of trimethyl phosphate as a stabilizer with respect to all acid components, 200 ppm of germanium dioxide as a polymerization catalyst with respect to all acid components, and 500 ppm of titanium tetrabutoxide with respect to all acid components were added, and the temperature in the reaction vessel was increased. Was maintained at 280 ° C., and a polycondensation reaction was performed for 3 hours under a reduced pressure of 5 mmHg or less to obtain a polyester resin. After drying the obtained polyester resin, 270 ° C.
A raw film was prepared by melt-extruding from a T-die at the resin temperature of. This raw film was stretched at 80 ° C. (T
The film was uniaxially stretched 4.5 times in the D direction) to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 1 shows the resin composition of the obtained film, the measurement result of the shrinkage ratio, and the evaluation result of the shrinkage unevenness.

Example 3 10% by weight of a polyester resin (A) consisting of 100 mol parts of terephthalic acid and 100 mol parts of butanediol, 82 mol parts of terephthalic acid, 11.5 mol parts of isophthalic acid, 6.5 mol parts of adipic acid and 90% by weight of a polyester resin (B) consisting of 100 parts by mole of ethylene glycol,
A polyester resin mixture was obtained by mixing using a twin-screw extruder. After drying the obtained polyester resin mixture,
A raw film was prepared by melt extrusion from a T die at a resin temperature of 270 ° C. This raw film is uniaxially stretched 4.5 times in the stretching direction (TD direction) at 70 ° C. to obtain a thickness of 4
A 0 μm heat-shrinkable polyester film was obtained. Table 1 shows the resin composition of the obtained film, the measurement result of the shrinkage ratio, and the evaluation result of the shrinkage unevenness.

Comparative Example 1 100 parts by mole of terephthalic acid, 140 parts of ethylene glycol
A molar part was placed in a reaction vessel, and the ester reaction was sufficiently performed under nitrogen pressure. Next, trimethyl phosphate as a stabilizer was added to the total acid component in an amount of 50 ppm, and antimony trioxide was added as a polymerization catalyst in an amount of 400 ppm to the total acid component.
Polycondensation reaction was performed for 3 hours under a reduced pressure of Hg or less to obtain a polyester resin. The obtained polyester resin was dried and then melt-extruded from a T die at a resin temperature of 270 ° C. to prepare a raw film. This raw film was uniaxially stretched 4.5 times in the stretching direction (TD direction) at 85 ° C. to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 1 shows the resin composition of the obtained film, the measurement result of the shrinkage ratio, the shrinkage unevenness, and the evaluation result of the adhesiveness.

Comparative Example 2 100 parts by mole of terephthalic acid and 140 parts of ethylene glycol
A molar part and 35 molar parts of cyclohexanedimethanol were placed in a reaction vessel, and the ester reaction was sufficiently carried out under nitrogen pressure. Next, trimethyl phosphate as a stabilizer was added to the total acid components in an amount of 50 ppm, and antimony trioxide was added as a polymerization catalyst in an amount of 400 ppm to the total acid components. Polycondensation reaction was performed under reduced pressure for 3 hours to obtain a polyester resin. After drying the obtained polyester resin, 270 ° C.
A raw film was prepared by melt-extruding from a T-die at the resin temperature of. This raw film was stretched at 85 ° C. in the stretching direction (T
The film was uniaxially stretched 4.5 times in the D direction) to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 1 shows the resin composition of the obtained film, the measurement result of the shrinkage ratio, the shrinkage unevenness, and the evaluation result of the adhesiveness.

Comparative Example 3 10 mol parts of dimethyl terephthalate, 90 mol parts of dimethyl naphthalenedicarboxylate, 220 mol parts of ethylene glycol and 10 mol parts of cyclohexanedimethanol were placed in a reaction vessel, and manganese acetate was used as a transesterification catalyst for all acid components. On the other hand, 400 ppm was added, and the transesterification reaction was sufficiently carried out. Next, 250 ppm of trimethyl phosphate as a stabilizer for all acid components and 400 ppm of antimony trioxide as a polymerization catalyst for all acid components
Add and maintain the temperature in the reaction vessel at 280 ° C.
Polycondensation reaction was performed for 3 hours under reduced pressure of mHg or less to obtain a polyester resin. The obtained polyester resin was dried and then melt-extruded from a T die at a resin temperature of 290 ° C. to prepare a raw film. This raw film was uniaxially stretched 4.5 times in the stretching direction (TD direction) at 95 ° C. to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 1 shows the resin composition of the obtained film, the measurement result of the shrinkage ratio, the shrinkage unevenness, and the evaluation result of the adhesiveness.

Comparative Example 4 60 mol parts of terephthalic acid, 25 mol parts of isophthalic acid, 15 mol parts of adipic acid and 140 mol parts of ethylene glycol were placed in a reaction vessel, and the ester reaction was sufficiently carried out under nitrogen pressure. Next, 100 ppm of trimethyl phosphate as a stabilizer was added to all acid components, and 450 ppm of antimony trioxide was added as a polymerization catalyst to all acid components, and the temperature in the reaction vessel was maintained at 280 ° C.
Polycondensation reaction was performed for 3 hours under reduced pressure of g or less to obtain a polyester resin. After drying the obtained polyester resin,
A raw film was prepared by melt extrusion from a T die at a resin temperature of 270 ° C. This raw film is uniaxially stretched 4.5 times in the stretching direction (TD direction) at 85 ° C. to obtain a thickness of 4
A 0 μm heat-shrinkable polyester film was obtained. Table 1 shows the resin composition of the obtained film, the measurement result of the shrinkage ratio, the shrinkage unevenness, and the evaluation result of the adhesiveness.

Comparative Example 5 80 mol parts of terephthalic acid, 20 mol parts of isophthalic acid, 140 mol parts of ethylene glycol and 15 mol parts of cyclohexanedimethanol were placed in a reaction vessel, and the ester reaction was sufficiently carried out under nitrogen pressure. Next, 200 ppm of trimethyl phosphate as a stabilizer with respect to the total acid component,
Antimony trioxide was used as a polymerization catalyst for all acid components.
50 ppm was added, the temperature in the reaction vessel was maintained at 280 ° C., and a polycondensation reaction was performed for 4 hours under a reduced pressure of 5 mmHg or less to obtain a polyester resin. The obtained polyester resin was dried and then melt-extruded from a T die at a resin temperature of 270 ° C. to prepare a raw film. This raw film was uniaxially stretched 4.5 times in the stretching direction (TD direction) at 85 ° C. to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 1 shows the resin composition of the obtained film, the measurement result of the shrinkage ratio, and the evaluation result of the shrinkage unevenness, the adhesiveness, and the adhesiveness.
It was shown to.

Comparative Example 6 88 mol parts of terephthalic acid, 12 mol parts of isophthalic acid, 140 mol parts of ethylene glycol, 5 mol parts of cyclohexanedimethanol and 3 mol parts of butanediol were placed in a reaction vessel, and the ester reaction was sufficiently performed under nitrogen pressure. Went to. Next, trimethyl phosphate as a stabilizer was added to the total acid component in an amount of 50 ppm, antimony trioxide was added as a polymerization catalyst in an amount of 300 ppm, and titanium tetrabutoxide was added to the total acid component in an amount of 500 ppm. While maintaining the temperature at 280 ° C., a polycondensation reaction was performed for 3 hours under a reduced pressure of 5 mmHg or less to obtain a polyester resin.
The obtained polyester resin was dried and then melt-extruded from a T die at a resin temperature of 270 ° C. to prepare a raw film. This raw film was uniaxially stretched 4.5 times in the stretching direction (TD direction) at 85 ° C. to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 1 shows the resin composition of the obtained film, the measurement result of the shrinkage ratio, the shrinkage unevenness, and the evaluation result of the adhesiveness.

[0038]

[Table 1]

The components shown in the table are as follows. TPA: terephthalic acid component IPA: isophthalic acid component NDA: naphthalene dicarboxylic acid component ADA: adipic acid component EG: ethylene glycol component CHDM: cyclohexanedimethanol component BDO: butanediol component

[0040]

EFFECT OF THE INVENTION The heat-shrinkable polyester film of the present invention has a high heat-shrinkage rate even at a relatively low temperature, has excellent shrinkage adhesion to a container such as a bottle, and has no shrinkage unevenness and excellent adhesion. It can be shrink-coated and has excellent practicality as various packaging materials, and is particularly suitable as a heat-shrinkable label for plastic bottles.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technology display location C08L 67:00 (72) Inventor Tajiri Zouun 2-3 of Ushikawa Dori, Toyohashi City, Aichi Prefecture Ryo Rayon Co., Ltd. Toyohashi Office

Claims (1)

[Claims] 1. A shrinkage ratio (S ₆₀ ), which comprises a polyester resin comprising an acid component containing an aromatic dicarboxylic acid or an ester-forming derivative thereof as a main component and an alcohol component, and contracted in warm water at 60 ° C. for 1 minute (S ₆₀ ). Shrinkage after 1 minute of shrinkage in warm water at ₇₀ ° C (S ₇₀ ), Shrinkage after shrinking in warm water of 80 ° C for 1 minute (S ₈₀ ) Shrinkage after shrinking in warm water of 90 ° C for 1 minute (S ₉₀ ) satisfies the following formulas (1) to (3), which is a heat-shrinkable polyester film. [Equation 1] S ₆₀ ≧ 5% ・ ・ ・ (1) [Equation 2] S ₈₀ ≧ 30% ・ ・ ・ (2) [Equation 3] S ₉₀ −S ₈₀ > S ₈₀ −S ₇₀・ ・ ・ (3 )