JPH0827260A - Heat-shrinkable polyester film - Google Patents

Abstract

PURPOSE:To prepare a heat-shrinkable polyester film having a high shrinkage factor at relatively low temperatures, excellent in shrink-adherence to a container such as a bottle and ink-adhesive properties and having no shrink- unevenness. CONSTITUTION:This heat-shrinkable polyester film is made of a polyester resin which comprises acid components mainly comprising an aromatic dicarboxylic acid or its ester forming derivative and alcohol components mainly comprising ethylene glycol. The sum of a ratio of acid components except terephthalic acid to the total acid components and a ratio of alcohol components except ethylene glycol to the total alcohol components is in the range of 10-50mol%. The polyester resin contains 1-30mol% cyclohexanedimethanol component and 1-20mol% butanediol component based on the total alcohol components.

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 characteristics at low temperature and solvent adhesion, and a shrinkable coating without uneven shrinkage. The present invention relates to a heat-shrinkable polyester film that can be provided.

[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, when these heat-shrinkable polyester films are used, for example, as heat-shrinkable labels for containers such as bottles, the end portions of the heat-shrinkable films are generally used by solvent-bonding with a solvent such as tetrahydrofuran to form a tube. For this reason, there is also a problem that the label is peeled off if the adhesive is not sufficiently adhered at the ends, that is, the solvent adhesiveness is not sufficient.
An object of the present invention is to provide an excellent heat-shrinkable polyester film which has excellent shrinkage properties at low temperatures and solvent adhesiveness, and in which uneven shrinkage does not occur and remains.

[0008]

In view of such circumstances, the inventors of the present invention have arrived at the present invention as a result of earnestly investigating a polyester resin constituting a heat-shrinkable film. That is, the heat-shrinkable polyester film of the present invention is composed of a polyester resin composed of an acid component having an aromatic dicarboxylic acid or an ester-forming derivative thereof as a main component and an alcohol component having ethylene glycol as a main component, and the polyester resin is entirely When the ratio of the acid component other than terephthalic acid in the acid component (A mol%) and the ratio of the alcohol component other than ethylene glycol in the total alcohol component (B mol%) are in the range of 10 mol% ≦ A + B ≦ 50 mol% 1 to 30 mol% cyclohexanedimethanol component and 1 butanediol component in all alcohol components
It is characterized in that it is contained in a proportion of ˜20 mol%.

The polyester resin used in the heat-shrinkable polyester film of the present invention comprises an acid component containing aromatic dicarboxylic acid or its ester-forming derivative as a main component and an alcohol component containing ethylene glycol as a main component. The ratio (A mol%) of acid components other than terephthalic acid in the total acid components and the ratio (B mol%) of alcohol components other than ethylene glycol in the total alcohol components are
It is necessary that the range of 10 mol% ≦ A + B ≦ 50 mol% is satisfied. This is the ratio (A mol%) of acid components other than terephthalic acid in the total acid components and the ratio (B mol%) of alcohol components other than ethylene glycol in the total alcohol components.
When the sum (A + B) is less than 10 mol%, sufficient solvent adhesiveness cannot be obtained. On the contrary, when the sum (A + B) exceeds 50 mol%, the solvent resistance of the film itself is poor, and film formation is possible. This is because no resin is obtained, preferably 15 to 45.
It is in the range of mol%.

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. These aromatic dicarboxylic acids or their ester-forming derivatives are preferably contained in the acid component of the polyester resin in an amount of 70 mol% or more, more preferably 80 mol% or more. this is,
This is because when the aromatic dicarboxylic acid or its ester-forming derivative is less than 70 mol%, the mechanical strength of the formed polyester film tends to decrease. 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.

The alcohol component constituting the polyester resin in the present invention contains ethylene glycol as a main component, and the total alcohol component contains ethylene glycol in an amount of 50 mol% or more, preferably 70 mol% or more. It is a thing. 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.

Further, in the present invention, a cyclohexanedimethanol component and a butanediol component are used as alcohol components for the purpose of reducing the occurrence of shrinkage unevenness and alleviating the shrinkage unevenness, and improving shrinkage characteristics and solvent adhesiveness at low temperatures. Include. Thus, by using the cyclohexanedimethanol component and the butanediol component together, it is possible to obtain a heat-shrinkable polyester film having an excellent balance between shrinkage characteristics and uneven shrinkage at low temperatures and excellent solvent adhesion. Is.

The content ratio of the cyclohexanedimethanol component is in the range of 1 to 30 mol%, preferably 5 to 25 mol% in the total alcohol component. If the proportion of the cyclohexanedimethanol component is less than 1 mol%, uneven shrinkage is likely to occur, and the phenomenon of increasing shrinkage in a relatively high temperature range does not appear, and uneven shrinkage cannot be sufficiently relaxed. This is because, on the contrary, when it exceeds 30 mol%, the shrinkage initiation temperature becomes high and the shrinkage property at low temperature is deteriorated. In this way, by containing the cyclohexanedimethanol component as the alcohol component in a specific ratio, it is possible to increase the shrinkage ratio in a relatively high temperature range, and when shrinkage unevenness occurs in a relatively low temperature range. Moreover, the generated shrinkage unevenness can be alleviated in a relatively high temperature region, and excellent shrinkage coating without shrinkage unevenness can be performed.

The content ratio of the butanediol component is in the range of 1 to 20 mol%, preferably 3 to 18 mol% in the total alcohol components. This is because if the proportion of butanediol is less than 1 mol%, the shrinkage initiation temperature becomes high, shrinkage unevenness is likely to occur at low temperatures, and shrinkage unevenness is likely to occur.
On the contrary, if it exceeds 20 mol%, the shrinkage initiation temperature is significantly lowered and the shrinkage occurs even in the temperature range near room temperature.

In addition to the above alcohol components, other alcohol components such as ethylene oxide adducts of bisphenol compounds or their derivatives, propylene glycol, triethylene glycol, diethylene glycol, neopentyl glycol, polyethylene glycol, polytetramethylene glycol, etc. It can also be used within a range that does not impair the effects of the present invention.

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.

In the present invention, the polyester resin is not limited to a single polyester resin, but may be a mixed polyester resin in which two or more polyester resins are mixed, and the proportion of acid components other than terephthalic acid in the total acid component (A
Mol%) and the proportion of alcohol components other than ethylene glycol in all alcohol components (B mol%) are 10 mol%
It may be in the range of ≦ A + B ≦ 50 mol%, and the cyclohexanedimethanol component and the butanediol component may be contained in proportions of 1 to 30 mol% and 1 to 20 mol% in the total alcohol components, respectively.

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 obtained 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 film is stretched 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 heat-shrinkable polyester film of the present invention has a shrinkage ratio of 5% or more when it is immersed in hot water at 60 ° C. for 1 minute without weighting to be shrunk, and in hot water at 80 ° C. without load. It is preferable that the shrinkage ratio when soaked for a minute to shrink is 30% or more. This is because if the shrinkage ratio at 60 ° C. is less than 5%, the film tends not to be sufficiently adhered to the container, and the heating temperature in the shrinking process must be increased, and the heating temperature in the shrinking process is increased. This is because the container such as a bottle is deformed or whitened, and the heat-shrinkable film is rapidly shrunk to cause uneven shrinkage. Considering the occurrence of uneven shrinkage due to abrupt shrinkage when the film shrinks, the shrinkage ratio at 60 ° C. is more preferably in the range of 10 to 30%. If the shrinkage ratio at 80 ° C is less than 30%, a sufficient shrinkage amount cannot be obtained,
This is because the adhesion of the film to the container tends to be insufficient, and it tends to be difficult to completely cover a container or the like having a particularly complicated shape. Considering the occurrence of shrinkage unevenness due to abrupt shrinkage when the film shrinks, it is more preferable that the shrinkage ratio at 80 ° C. is in the range of 35 to 60%.
Further, in the present invention, it is preferable that the shrinkage initiation temperature is 50 ° C. or lower in order to obtain excellent low temperature shrinkage characteristics, and more preferably at least 1 at 50 ° C.
%, More preferably 2% or more.

The heat-shrinkable polyester film of the present invention has a shrinkage ratio of 9 after being shrunk in warm water at 80 ° C. for 1 minute.
It is preferable that the difference from the shrinkage ratio obtained by shrinking in warm water of 0 ° C. 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,
Even when shrinkage unevenness occurs in the temperature range up to 80 ° C,
This is because the generated shrinkage unevenness can be alleviated in this temperature range, and excellent shrinkage coating without shrinkage unevenness can be performed.
This is because if the difference in shrinkage ratio in this temperature range is less than 3%, the shrinkage unevenness generated during shrinkage cannot be alleviated and the shrinkage unevenness tends to remain. Considering occurrence of uneven shrinkage due to abrupt shrinkage, adhesion to a container, etc., it is more preferable that the difference in shrinkage ratio is in the range of 5 to 15%.

Further, in the present invention, the shrinkage factor (S ₅₀ ) of shrinking in warm water of 50 ° C. for 1 minute, the shrinkage factor of shrinking in 1 minute of warm water of 60 ° C. (S ₆₀ ) and the hot water of 70 ° C. Shrinkage (S ₇₀ ) after shrinking for 1 minute in water, 1 in hot water at 80 ° C
The contraction rate (S ₈₀ ) contracted for a minute is calculated by the following equation (1) to
Those satisfying (3) are preferable.

[0025]

[Formula 1] 5% ≦ S ₆₀ −S ₅₀ ≦ 20% (1)

[0026]

[Formula 2] 10% ≦ S ₇₀ −S ₆₀ ≦ 30% (2)

[0027]

Equation 3] _{5% ≦ S 80 -S 70 ≦} 25% ··· (3) which, when the difference in shrinkage rate shown by the formula (1) to (3) is smaller than the range, complete shrinkage This is because the amount of shrinkage at that time is small and it tends to be impossible to completely shrink-coat the container and the like. Conversely, if the difference in these shrinkage ratios is larger than each range, the temperature will suddenly increase in each temperature range. This tends to cause various shrinkages, resulting in uneven shrinkage. Preferably, S ₅₀ , S ₆₀ , S ₇₀ , S ₈₀ and S ₉₀ are in the range that satisfies the following formulas (4) to (6).

[0028]

[Formula 4] 10% ≦ S ₆₀ −S ₅₀ ≦ 15% (4)

[0029]

[Equation 5] 15% ≦ S ₇₀ −S ₆₀ ≦ 25% (5)

[0030]

10% ≦ S ₈₀ −S ₇₀ ≦ 20% (6) The thickness of the heat-shrinkable polyester film of the present invention is not particularly limited, but it is preferably 1 to 600 μm. Used practically. For packaging purposes, particularly packaging of foods, beverages, pharmaceuticals, etc., those having a range of 6 to 380 μm are used. When used for labels such as PET bottles, polyethylene bottles, glass bottles, 20 to 7
Those having a range of 0 μm are used.

Various known processing treatments and suitable additives may be added to the present invention in order to impart more specific performance. 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.

[0032]

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.

[0033]

## EQU00007 ## Shrinkage (%) = {(L-L ') / L} * 100 Heat unevenness is 150 mm in the stretching direction and 2 in the direction perpendicular to it.
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.

Solvent adhesiveness is 100 mm in the stretching direction and 20 mm in a direction perpendicular to the stretching direction. Two polyester films are cut out, tetrahydrofuran is applied to the end 10 mm of one film, and the other film is superposed. Bonded together and left at room temperature for 24 hours, then temperature 25 ℃, pulling speed 40mm / sec, chuck interval 50mm
Then, a T-peel test was performed on 5 samples using an autograph manufactured by Shimadzu Corporation. ◎: No adhesion peeling of 5 pieces, no film breakage ○: No adhesion peeling of 5 pieces The film is broken. Δ: 3 to 4 adhesive parts are not peeled, but the film is broken. X: 3 or more adhesive parts are peeled or cannot be bonded.

Example 1 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 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, the shrinkage unevenness, and the evaluation result of the solvent adhesiveness.

Example 2 87 mol parts of terephthalic acid, 13 mol parts of isophthalic acid, 140 mol parts of ethylene glycol, 13 mol parts of cyclohexanedimethanol and 15 mol parts of butanediol were placed in a reaction vessel, and the ester reaction was sufficiently carried out 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. 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, the shrinkage unevenness, and the evaluation result of the solvent adhesiveness.

Example 3 23% by weight of a polyester resin (A) consisting of 100 mol parts of terephthalic acid component and 100 mol parts of ethylene glycol component, 100 mol parts of terephthalic acid component, 70 mol parts of ethylene glycol component and 30 mol of cyclohexanedimethanol component. 67% by weight of the polyester resin (B), 100 parts by weight of the terephthalic acid component, and 10% by weight of the polyester resin (C) of 100 parts by weight of the butanediol component are mixed using a twin-screw extruder. A polyester resin mixture containing 20 mol% of cyclohexane dimethanol and 10 mol% of butanediol in the total alcohol component was obtained. The obtained polyester resin mixture was dried and then melt-extruded from a T die at a resin temperature of 270 ° C. to prepare a raw film. This original film,
Uniaxial stretching of 4.5 times was performed at 80 ° C. in the stretching direction (TD 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 solvent adhesiveness.

Example 4 45% by weight of a polyester resin (A) consisting of 70 parts by mole of terephthalic acid component, 30 parts by mole of isophthalic acid component and 100 parts by mole of ethylene glycol component, 1 part of terephthalic acid component
42 parts by weight of a polyester resin (B) consisting of 00 parts by mole, 70 parts by mole of ethylene glycol component and 30 parts by mole of cyclohexanedimethanol component, 100 parts of terephthalic acid component
13 parts by weight of a polyester resin (C) consisting of 100 parts by weight of butanediol component are mixed using a twin-screw extruder, and 13 mol% of isophthalic acid component and all alcohols are contained in all acid components in the mixed resin. A polyester resin mixture containing 12 mol% of cyclohexanedimethanol and 5 mol% of butanediol in the components was obtained. The obtained polyester resin mixture 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 stretched at 80 ° C. in the stretching direction (TD direction) by 4.5
Double uniaxial stretching was performed 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 solvent adhesiveness.

[0039]

[Table 1]

Comparative Example 1 100 parts by mole of terephthalic acid and 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 2 shows the resin composition of the obtained film, the measurement result of the shrinkage rate, the shrinkage unevenness, and the evaluation result of the solvent 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 2 shows the resin composition of the obtained film, the measurement result of the shrinkage rate, the shrinkage unevenness, and the evaluation result of the solvent adhesiveness.

Comparative Example 3 100 parts by mole of terephthalic acid and 140 of ethylene glycol
A molar part, 30 molar parts of cyclohexane dimethanol and 40 molar parts of butanediol were placed in a reaction vessel, and the ester reaction was sufficiently carried out under nitrogen pressure. Next, trimethyl phosphate as a stabilizer is added to the total acid component at 50 pp.
m, 400 ppm of antimony trioxide as a polymerization catalyst was added to all the acid components, the temperature in the reaction vessel was maintained at 280 ° C., and 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 very brittle and could not be formed as a shrink film.

Comparative Example 4 100 mol parts of dimethyl terephthalate, 240 mol parts of ethylene glycol, and 50 mol parts of butanediol were placed in a reaction vessel, and titanium tetrabutoxide was added as an ester exchange catalyst in an amount of 500 ppm with respect to all acid components. The exchange reaction was carried out sufficiently. Then, the temperature in the reaction vessel was maintained at 270 ° C., and a polycondensation reaction was carried out 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 subjected to 4.5 at 85 ° C in the stretching direction (TD direction).
Double uniaxial stretching was performed to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 2 shows the resin composition of the obtained film, the measurement result of the shrinkage rate, the shrinkage unevenness, and the evaluation result of the solvent adhesiveness.

Comparative Example 5 98 mol parts of terephthalic acid, 2 mol parts of isophthalic acid, 140 mol parts of ethylene glycol, 1 mol part of cyclohexanedimethanol and 1 mol part of butanediol were placed in a reaction vessel, and the ester reaction was sufficiently performed under nitrogen pressure. Went to. Next, 100 ppm of trimethyl phosphate as a stabilizer was added to all the acid components, and 450 ppm of antimony trioxide was added as a polymerization catalyst to all the acid components, and the temperature in the reaction vessel was kept at 280 ° C. to 5 mmHg or less. Polycondensation reaction was performed under reduced pressure for 3 hours 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 2 shows the resin composition of the obtained film, the measurement result of the shrinkage rate, the shrinkage unevenness, and the evaluation result of the solvent adhesiveness.

Comparative Example 6 80 mol parts of terephthalic acid, 20 mol parts of isophthalic acid, 140 mol parts of ethylene glycol and 3 mol parts of butanediol 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 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 4 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 2 shows the resin composition of the obtained film, the measurement result of the shrinkage rate, the shrinkage unevenness, and the evaluation result of the solvent adhesiveness.

Comparative Example 7 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 2 shows the resin composition of the obtained film, the measurement result of the shrinkage rate, the shrinkage unevenness, and the evaluation result of the solvent adhesiveness.

Comparative Example 8 95 mol parts of terephthalic acid, 5 mol parts of isophthalic acid, 140 mol parts of ethylene glycol, and 40 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 all acid components and 45 ppm of antimony trioxide as a polymerization catalyst with respect to all acid components were used.
0 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 original film,
Uniaxial stretching of 4.5 times in the stretching direction (TD direction) was performed at 85 ° C. to obtain a heat-shrinkable polyester film having a thickness of 40 μm. Table 2 shows the resin composition of the obtained film, the measurement result of the shrinkage rate, the shrinkage unevenness, and the evaluation result of the solvent adhesiveness.

Comparative Example 9 100 mol parts of dimethyl terephthalate, 200 mol parts of ethylene glycol, 10 mol parts of cyclohexane dimethanol and 40 mol parts of butanediol were placed in a reaction vessel, and titanium tetrabutoxide was used as a transesterification catalyst for all acid components. On the other hand, 500 ppm was added to sufficiently carry out the transesterification reaction. Then, the temperature in the reaction vessel was maintained at 270 ° C., and a polycondensation reaction was carried out 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 2 shows the resin composition of the obtained film, the measurement result of the shrinkage rate, the shrinkage unevenness, and the evaluation result of the solvent adhesiveness.

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[Table 2]

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

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EFFECT OF THE INVENTION The heat-shrinkable polyester film of the present invention has a high heat-shrinkage ratio even at a relatively low temperature, has excellent shrink adhesion and solvent adhesion to a container such as a bottle, and has a uniform shrinkage coating. It can be used for various purposes and is highly practical as various packaging materials, and is particularly suitable as a heat-shrinkable label for plastic bottles.

Front Page Continuation (72) Inventor Tajiri Zouun 2-4-1, Ushikawa-dori, Toyohashi City, Aichi Sanryo Rayon Co., Ltd. Toyohashi Plant

Claims (1)

[Claims] 1. 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 containing ethylene glycol as a main component, and the polyester resin is other than terephthalic acid in all acid components. Of the acid component (A mol%) and the ratio of alcohol components other than ethylene glycol (B mol%) in the total alcohol component are 10 mol% ≦ A + B ≦ 50 mol%
And a cyclohexanedimethanol component in a proportion of 1 to 30 mol% and a butanediol component in a proportion of 1 to 20 mol% in all alcohol components.