JPH05254015A - Polyester-based shrink film - Google Patents

Abstract

PURPOSE:To obtain shrink film having specified heat shrink characteristics by a method wherein polyester composition prepared by mixing polyester, which is obtained by polycondensing mixed diol constituent having specified composition and dicarboxylic acid constituent mainly made of terephthalic acid, with polyester, which is obtained by polycondensing mixed dicarboxylic constituent having specified composition and diol constituent mainly made of ethylene glycol, in the specified ratio is formed. CONSTITUTION:Film is formed out of the polyester composition consisting of 75-55wt.% of polyester, which is composed of dicarboxylic acid constituent unit mainly made of terephthalic acid and mixed diol constituent unit consisting of 80-60mol.% of ethylene glycol and 20-40mol.% of cyclohexane dimethanol, and 25-45wt.% of polyester, which is composed of mixed dicarboxylic acid constituent unit consisting of 90-75mol.% of terephthalic acid and 10-25mol.% of adipic acid and diol constituent unit mainly made of ethylene glycol and, in addition, the adipic acid constituent unit in the total dicarboxylic acid constituent unit is 4-10mol.%, so as to stretch at least to one direction by the draw ratio of 150-800% in order to obtain the shrink film concerned.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel polyester shrink film, and more specifically, there is no distortion or wrinkling of a pattern due to uneven shrinkage at the time of wearing, and a good finished appearance, and low temperature shrinkability. Because of its superiority, in plastic bottles such as PET bottles, especially in pre-labels where the film is mounted before filling the contents,
The bottle will not be deformed by heat or the shrinking force of the film,
The present invention relates to a polyester-based shrink film suitable for labels such as plastic bottles and glass bottles, cap seals, and other packaging materials.

[0002]

2. Description of the Related Art In recent years, polyester-based shrink films have excellent transparency, and shrinkage during transportation and storage,
In other words, since it does not cause dimensional insufficiency or flatness deterioration due to natural shrinkage, it is attracting attention as a label, a cap seal, and other packaging materials for mounting on plastic bottles and glass bottles by heating and shrinking. ..

In order to develop the required heat shrinkage, a copolymerization component is added to polyethylene terephthalate (Japanese Patent Laid-Open No. 156833/1988) or polyethylene terephthalate is blended with the copolymer (Japanese Patent Publication No. Sho. No. 64-10332), and polybutylene terephthalate is blended with a polyester-based copolymer in order to impart low-temperature shrinkability (JP-A-59-9).
No. 7175) has been attempted.

However, a polyester-based shrink film composed of a conventional polyester-based copolymer or a blended product thereof with polyethylene terephthalate or polybutylene terephthalate is a polyvinyl chloride-based or polystyrene-based one conventionally used as a shrink film. Compared with, the temperature dependence of the heat shrinkage is large,
Since a rapid increase in the heat shrinkage occurs near the glass transition temperature, pattern distortion and wrinkles occur due to uneven shrinkage during mounting, and the finished appearance is impaired, and low temperature shrinkability Since the shrinkage force is too strong even if it is held, there is a drawback in that plastic bottles such as PET bottles may be deformed, especially in the case of a pre-label in which a film is attached before filling the contents.

[0005]

DISCLOSURE OF THE INVENTION The present invention overcomes the drawbacks of the conventional polyester type shrink film, and there is no distortion or wrinkling of the pattern due to uneven shrinkage at the time of mounting, and the finished appearance is good. In addition, it has excellent low-temperature shrinkability, and in plastic bottles such as PET bottles, even in pre-labels where the film is attached before filling the contents, the polyester shrink film does not deform due to heat or the shrinking force of the film. It is made for the purpose of providing.

[0006]

DISCLOSURE OF THE INVENTION In order to develop a polyester-based shrink film having the above-mentioned preferable properties, the inventors of the present invention have conducted diligent research on improving the physical properties of the film, and as a result, have found that it has a specific composition. Polyester obtained by polycondensing a diol component and a dicarboxylic acid component mainly containing terephthalic acid, and polyester obtained by polycondensing a mixed dicarboxylic acid component having a specific composition and a diol component mainly containing ethylene glycol And a polyester obtained by polycondensing a mixed diol component having another specific composition and a dicarboxylic acid component mainly composed of terephthalic acid, which are optionally used, in a specific ratio to form a polyester composition. Specific heat shrinkage obtained by stretching the resulting film in at least one direction at a specific ratio The shrink film with sex, found that can achieve the purpose, and completed the present invention based on this finding.

That is, the present invention comprises (A) a dicarboxylic acid component unit mainly composed of terephthalic acid and a mixed diol component unit comprising 80 to 60 mol% of ethylene glycol and 20 to 40 mol% of cyclohexanedimethanol. And (B) a mixed dicarboxylic acid component unit consisting of 90 to 75 mol% terephthalic acid and 10 to 25 mol% adipic acid, and a diol component unit mainly composed of ethylene glycol. A polyester composition comprising 25 to 45% by weight of polyester and containing 4 to 10 mol% of adipic acid component units in all dicarboxylic acid component units, or 75 to 55% by weight of the component (A) polyester; (B) component 25 to 45% by weight of polyester, and all dicarboxylic acid components alone. Adipic acid component units in 4 to 10
(C) a dicarboxylic acid component unit mainly composed of terephthalic acid, and a mixed diol component unit consisting of 77 to 70 mol% of ethylene glycol and 23 to 30 mol% of diethylene glycol, based on 100 parts by weight of the polyester mixture which is mol%. A film formed from a polyester composition containing 2 to 10 parts by weight of the polyester thus formed is stretched in at least one direction by 1.5 to 8 times.
Thermal shrinkage in one direction is 30% or more at 70 ℃ 100 ℃
Of 60% or more and the heat shrinkage ratio in the direction perpendicular thereto is 10% or less at 100 ° C. The polyester shrink film is provided.

The base resin used in the shrink film of the present invention includes the above-mentioned component (A) polyester,
A mixture with the polyester as the component (B) can sufficiently achieve the object of the present invention, but the film requires a higher degree of shrinkage performance in order to develop a good finished appearance like a rectangular bottle. When it is attached to a bottle or the like, a mixture of the polyester as the component (A), the polyester as the component (B) and the polyester as the component (C) is preferable.

The component (A) polyester and the component (C) polyester are obtained by a polycondensation reaction between a dicarboxylic acid component mainly containing terephthalic acid and a specific mixed diol component, and the component (B) polyester is specific mixture. It is formed by a polycondensation reaction between a dicarboxylic acid component and a diol component mainly composed of ethylene glycol.

The dicarboxylic acid component unit in the component (A) polyester and the component (C) polyester is preferably a terephthalic acid unit of 80 mol% or more, particularly preferably 85 mol% or more, and an aromatic dicarboxylic acid containing terephthalic acid. It is preferable that the component unit contains 96 mol% or more, and particularly 98 mol% or more. When the proportion of terephthalic acid units decreases, the mechanical strength of the obtained film decreases.
Further, when the dicarboxylic acid component unit other than the aromatic dicarboxylic acid component unit containing terephthalic acid, such as an aliphatic dicarboxylic acid or a polycarboxylic acid, exceeds 4 mol%, a decrease in glass transition temperature or partial cross-linking of the polyester easily occurs,
Not only the object of the present invention cannot be achieved, but the propensity for extension is reduced.

As the carboxylic acid component unit other than the terephthalic acid unit which may be present in the dicarboxylic acid component unit,
For example, isophthalic acid, biphenyldicarboxylic acid, 5-tert-butylisophthalic acid, 2,2,6,6-tetramethylbiphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,1,3-trimethyl-3-phenylindene Aromatic dicarboxylic acid units such as 4,5-dicarboxylic acid, oxalic acid, succinic acid, adipic acid, azelaic acid,
Units of aliphatic dicarboxylic acid such as sebacic acid and 1,10-decanedioic acid, units of trifunctional or higher polyfunctional carboxylic acid such as trimellitic acid and 1,2,4,5-benzenetetracarboxylic acid Is mentioned.

The dicarboxylic acid component unit in the component (B) polyester is 90 to 75 mol% of terephthalic acid,
It is preferably composed of 87 to 77 mol% and adipic acid of 10 to 25 mol%, preferably 13 to 23 mol%. When the content of adipic acid is less than 10 mol%, the glass transition temperature of the polyester as the component (A) is Difference is less than 25 ° C., and a good finished appearance cannot be obtained at the time of mounting. If it exceeds 25 mol%, the glass transition temperature does not change from room temperature and crystallization becomes difficult, which makes practical use difficult. Further, the dicarboxylic acid component unit may contain units of other dicarboxylic acid components other than the above-mentioned two-component unit, if desired, as long as the physical properties of the polyester are not adversely affected. Examples of the unit of the dicarboxylic acid component include, for example, isophthalic acid, biphenyldicarboxylic acid, 5-tert-butylisophthalic acid, 2,2,6,6-tetramethylbiphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, Aromatic dicarboxylic acid units such as 1,1,3-trimethyl-3-phenylindene-4,5-dicarboxylic acid, oxalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, 1,10-decanedioic acid Units of aliphatic dicarboxylic acids such as trimellitic acid, 1, 2,
Examples include units of trifunctional or higher polyfunctional carboxylic acid such as 4,5-benzenetetracarboxylic acid.

On the other hand, the diol component unit in the component (A) polyester is an ethylene glycol unit 80-
60 mol%, preferably 75-65 mol% and cyclohexanedimethanol units 20-40 mol%, preferably 2
When the ratio of the cyclohexanedimethanol unit is more than 40 mol% or less than 20 mol%, the crystallinity becomes large and the desired heat shrinkability cannot be obtained. ..

In the diol component unit, other than the above-mentioned two-component units, other diol and polyol units may be contained in the total amount of the diol component units, if desired, as long as the physical properties of the polyester are not adversely affected. The amount may be 5 mol% or less, preferably 3 mol% or less. When the content of the units of the other diols and polyols exceeds 5 mol%, the specific amorphous property of the polyester is impaired, and the object of the present invention cannot be sufficiently achieved. Examples of such diols include diethylene glycol, propylene glycol, 1,4-butanediol,
Neopentyl glycol, 1,6-hexanediol,
Examples of the polyols include xylylene glycol and the like, and examples of the polyols include glycerin, pentaerythritol, and trimethylolpropane.

The diol component unit in the polyester as the component (B) is mainly composed of ethylene glycol units, that is, contains 90 mol% or more, preferably 95 mol% or more of ethylene glycol units. In addition to diethylene glycol, propylene glycol, 1,4-butanediol,
Neopentyl glycol, 1,6-hexanediol,
Cyclohexanedimethanol, xylylene glycol,
Units such as glycerin, pentaerythritol, and trimethylolpropane may be contained in a proportion of less than 10 mol%, preferably less than 5 mol%.

Further, the diol component unit in the component (C) polyester is an ethylene glycol unit 77.
.About.70 mol% and 23 to 30 mol% of diethylene glycol units. If the diethylene glycol unit exceeds 30 mol%, thermal decomposition tends to occur during melt processing, and if it is less than 23 mol%, the finished appearance after mounting Is the same as when this polyester is not added.

In addition to the above-mentioned two-component unit, the diol component unit may contain other diol or polyol units, if desired, within a range that does not adversely affect the physical properties of the polyester. Examples of such diols include propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, xylylene glycol and the like, and examples of polyols include glycerin, pentaerythritol and triglyceride. Methylolpropane etc. can be mentioned.

These polyesters used in the present invention are
It can be produced by subjecting the dicarboxylic acid component and the mixed diol component to a polycondensation reaction according to a usual polyester production method. At this time, if necessary, a reactive functional derivative of a dicarboxylic acid, such as an acid halide or an acid ester, can be used as the dicarboxylic acid component, or the reaction is performed in the presence of a reaction solvent, a condensing agent, a catalyst, or the like. You can also The degree of polymerization of the polyester used in the present invention is not particularly limited, but the intrinsic viscosity is 0.50 to 1.20, preferably 0.60 to 0.9.
It is preferably in the range of 0.

In the present invention, as the base material of the shrink film, the component (A) polyester is 75 to 55% by weight, preferably 72 to 58% by weight, and the component (B) polyester is 25 to 45% by weight, preferably 28 to 42%. % Of adipic acid component units in the total dicarboxylic acid component units in the composition.
Two-component polyester composition in which the content is mol%, or 2
(C) with respect to 100 parts by weight of the component-based polyester mixture
A three-component polyester composition containing 2 to 10 parts by weight, preferably 3 to 8 parts by weight of the component polyester is used.

In the two-component polyester composition, when the amount of the component (B) polyester is less than 25% by weight, the finished appearance after the shrink film is mounted is inferior.
If it exceeds 5% by weight, the desired heat shrinkage cannot be obtained. Further, when the adipic acid component unit in all the dicarboxylic acid component units in the composition is less than 4 mol%, the low temperature shrinkage is poor, and the heat shrinkage ratio at 70 ° C. does not become 30% or more, and exceeds 10 mol%. And the natural shrinkage rate increases.

On the other hand, in the three-component polyester composition, when the amount of the component (C) polyester added is less than 2 parts by weight, the finished appearance after mounting is the same as when the polyester is not added, and the two-component system is substantially the same. It becomes the same as in the case of the polyester composition, and when it exceeds 10 parts by weight, it is difficult to uniformly stretch and the strength of the film is lowered.

The apparent glass transition temperature of these polyester compositions is not particularly limited, but is 55 to 7
It is preferably in the range of 0 ° C.

The difference between the glass transition temperature of the polyester as the component (A) and the glass transition temperature of the polyester as the component (B) is preferably 25 ° C. or higher, and more preferably 30 ° C. or higher. When the difference in the glass transition temperature is less than 25 ° C, the performance of the single copolymer polyester obtained by combining the component (A) and the component (B) is substantially the same, and low temperature shrinkability can be exhibited. However, a good finished appearance may not be obtained after mounting. Further, by including the diethylene glycol component unit of the component (C) polyester in the component (A) polyester or the component (B) polyester or both, the content ratio of the diethylene glycol component in the polyester is made the same as that of the three-component polyester. Also, compared with the three-component polyester, the finished appearance after mounting is inferior, and it is almost the same as the two-component polyester containing no diethylene glycol component unit. These reasons are not exaggerated, but it seems that some heterogeneity in the very fine structure is involved.

In the shrink film of the present invention, a polyester composition is prepared by melt-kneading the above-mentioned (A) component polyester, (B) component polyester and optionally (C) component polyester in a predetermined ratio, It can be manufactured by forming a film by molding and then stretching the film at a predetermined stretching ratio.

In the present invention, a filler such as titanium oxide, fine particle silica, kaolin, calcium carbonate or the like may be added, if necessary, when the polyester composition is prepared, and an antistatic agent and an oxidizer may be added. Inhibitors, light stabilizers, colorants and the like may be added.

The film is formed by, for example, drying the polyester composition, melt-extruding it at a temperature in the range of 220 to 300 ° C., and casting it on a casting drum having a surface temperature of 15 to 70 ° C. to a thickness of about 100 to 500 μm. Film is formed. In the stretching treatment, the film thus obtained is at least 1.5 to 8 times, preferably 2 to 6 times in at least one direction at a glass transition temperature or higher, preferably 5 to 30 ° C. higher than the glass transition temperature. Double stretching is performed. If necessary after this stretching treatment, further heat treatment may be carried out in the range of a temperature 20 ° C lower than the stretching temperature to a temperature 20 ° C higher than the stretching temperature.
Thus, in one direction, a shrink film having a heat shrinkage of 70% at 30% or more, a heat shrinkage of 100 ° C at 60% or more, and a heat shrinkage of 10% or less at 100 at a right angle to the shrink film is obtained. Although it is obtained, in order to make the heat shrinkage in the transverse direction 30% or more at 70 ° C. and 60% or more at 100 ° C., the unstretched film is 1.
Stretching from 05 to 2.0 times, then with a tenter in the transverse direction from 3 to
It is advantageous to stretch the film 6 times and then wind it by heat treatment, or stretch it in the transverse direction with a tenter without longitudinal stretching and then heat it and wind it.

In this case, the stretching temperature in the roll type longitudinal stretching machine is preferably higher than the transverse stretching temperature in order to keep the heat shrinkage in the longitudinal direction within 10%.

The polyester shrink film of the present invention has a unidirectional heat shrinkage ratio of 30% or more at 70 ° C.,
It is necessary that the heat shrinkage rate at 100 ° C. is 60% or more, and the heat shrinkage ratio in the direction perpendicular thereto is 10% or less at 100 ° C. In the main shrinkage direction, the heat shrinkage at 70 ° C is 30
When it is less than%, in a plastic bottle such as a PET bottle, in particular, in a pre-label in which the film is attached before filling the contents, the film is formed into a bottle shape without being deformed by heat and maintaining a good finished appearance. Can not be installed along the
If the heat shrinkage ratio at 0 ° C. is less than 60%, the increase in the heat shrinkage ratio from 70 ° C. is too small, and the finished appearance after mounting is inferior. Also, 100 in the direction perpendicular to the main contraction direction
If the heat shrinkage rate at ℃ exceeds 10%, the design may be displaced or wavy after mounting.

Further, the polyester shrink film of the present invention has a temperature range in which the heat shrinkage rate is in the range of 1 to 20% in the heat shrinkage curve in the main shrinkage direction (hereinafter referred to as low shrinkage temperature range) of 8 ° C. or more. The temperature is preferably 10 ° C or higher, more preferably 12 ° C or higher.
In order to produce a good finished appearance without distortion and wrinkles of the pattern due to uneven shrinkage during mounting, the temperature dependence of the heat shrinkage rate, especially from the start of shrinkage to 20% It is necessary that the temperature dependence between them is small, in other words, the low shrinkage temperature region is wide. When the low shrinkage temperature region is less than 8 ° C., uneven shrinkage is likely to occur, which may cause distortion of patterns and wrinkles, which is not preferable. In addition, when it is attached to a rectangular bottle, it is required that the contraction behavior in the initial stage of heating at the time of attachment is slow.
It is preferably 2 ° C or higher.

The heat shrinkage stress of the film in the main shrinkage direction is preferably 0.9 kg / mm ² or less at 80 ° C., and particularly preferably 0.8 kg / mm ² or less. If the heat shrinkage stress at 80 ° C exceeds 0.9 kg / mm ² , PET
In a pre-label that attaches the film before filling the contents in a plastic bottle such as a bottle,
It is not preferable because the bottle may be deformed by the shrinking force of the film or may be crushed or crushed.

The thickness of the film of the present invention is not particularly limited, but is usually 15 to 150 μm, preferably 20.
˜70 μm. The strength of the film strainer varies slightly depending on the thickness of the film, but is generally about 13 times as a Young's modulus in a direction perpendicular to the main shrinkage direction.
0 kg / mm ² or more, when used with an automatic mounting machine 15
It is preferably 0 kg / mm ² or more.

The polyester shrink film of the present invention is subjected to surface treatments such as corona discharge treatment and plasma irradiation treatment, and various coatings such as primer treatment and antistatic coating to obtain adhesion of printing ink, metal vapor deposition and slipperiness. The anti-blocking property, easy sealing property, antistatic property and the like can also be improved.

[0033]

EFFECT OF THE INVENTION The polyester shrink film of the present invention is excellent in low-temperature shrinkability and has a good finished appearance without pattern distortion or wrinkles due to uneven shrinkage at the time of mounting. In bottles, especially in pre-labels where the film is attached before filling the contents, the shrink film for labels of plastic bottles, especially PET bottles, has the property that it can be attached without being deformed by heat or the shrinking force of the film. It is most suitable for use as a label or cap seal for other plastic bottles and glass bottles, and can be used in a wide range of packaging material fields that can exert the effects of the characteristics.

[0034]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

The heat shrinkage rate, low shrinkage temperature range, Young's modulus, wearability, and glass transition temperature in each example were determined according to the following methods.

(A) Heat Shrinkage The shrink film was cut into 100 mm square to prepare a sample, and the sample was dipped in a warm water bath adjusted to a predetermined temperature for 30 seconds, and then the vertical or horizontal dimensions were measured. Heat shrinkage of

[Equation 1] Sought according to.

(B) Low shrinkage temperature region The heat shrinkage rate is measured at intervals of 2 ° C. up to a temperature at which the heat shrinkage rate exceeds 20% from the shrinkage start temperature in the main shrinkage direction, and the shrinkage curve that can be drawn thereby is a heat shrinkage rate of 1%. And the temperatures reaching 20% are T [1] and T [20], respectively, and are calculated according to the low shrinkage temperature region (° C.) = T [20] −T [1].

(C) Young's modulus The shrink film is cut into a sample having a length of 120 mm and a width of 10 mm in the direction perpendicular to the main shrinkage direction to prepare a sample.
This sample has a chuck distance of 50 m at 23 ° C.
It is pulled by a load cell type tensile tester set to m and a pulling speed of 5 mm, and is calculated according to ASTM-D1894 from the slope of the initial straight line portion of the SS curve at this time.

(D) Wearability A round polyethylene terephthalate bottle having a capacity of 1.5 liters and a rectangular polyethylene terephthalate bottle having a capacity of 1 liter are filled with a checkerboard in an empty state in which the contents have not yet entered. Each shrink film attached was formed into a cylindrical shape with the main contraction direction being the circumferential direction, and fitted into the shrink tunnel at 130 ° C for 5 seconds to be contracted and attached, and the degree of cross-cut deformation and the presence of wrinkles The deformation of the bottle was observed and evaluated as follows.

◯: There is no defect in the finished appearance, Δ: There are some defects in the finished appearance, ×: The finished appearance is generally defective, or the bottle is deformed. Unmountable: Cannot be installed due to insufficient shrinkage under the specified conditions.

(E) Glass transition temperature Using a DSC measuring device manufactured by Perkin Elmer Co., Ltd., the temperature was raised to 300 ° C. at a rate of 20 ° C./min in a nitrogen stream, and then 200 ° C.
Quenching to 20 ° C at a rate of / min, and after 5 minutes again 20 ° C /
The temperature was raised to 300 ° C. at a rate of minutes, and the glass transition temperature (midpoint) at that time was determined.

Production Example 1 Production of Polyester Polymer A A stainless steel autoclave was charged with a predetermined amount of a mixture of terephthalic acid, ethylene glycol, and cyclohexanedimethanol, and the polycondensation reaction was carried out according to a conventional method. By continuing the above until the intrinsic viscosity reached 0.80, a polyester polymer A having a glass transition temperature of 80 ° C. was produced. This product was composed of 100 mol% of terephthalic acid unit as a dicarboxylic acid component unit, 70 mol% of ethylene glycol unit as a diol component unit and 30 mol% of cyclohexanedimethanol unit.

Production Example 2 Production of Polyester Polymer B-1 In the same manner as in Production Example 1, 80 mol% of terephthalic acid units and 20 mol% of adipic acid units as dicarboxylic acid component units, and 1 ethylene glycol unit of 1 as diol component unit.
A polyester polymer B-1 having an intrinsic viscosity of 0.70 and a glass transition temperature of 38 ° C., which was composed of 00 mol%, was produced.

Production Example 3 Production of Polyester Polymer B-2 In the same manner as in Production Example 1, 85 mol% of terephthalic acid units and 15 mol% of adipic acid units as dicarboxylic acid component units, and 1 ethylene glycol unit of 1 as diol component unit.
A polyester polymer B-2 having an intrinsic viscosity of 0.70 and a glass transition temperature of 47 ° C., which was composed of 00 mol%, was produced.

Production Example 4 Production of Polyester Polymer C In the same manner as in Production Example 1, 100 mol% of terephthalic acid units as dicarboxylic acid component units, 75 mol% of ethylene glycol units as diol component units and 25 mol% of diethylene glycol units. Intrinsic viscosity 0.7
0, a polyester polymer C having a glass transition temperature of 55 ° C. was produced.

Production Example 5 Production of Polyester Polymer D In the same manner as in Production Example 1, 94 mol% of terephthalic acid units and 6 mol% of adipic acid units as dicarboxylic acid component units, and 7 mol of ethylene glycol units as diol component units.
Intrinsic viscosity 0.80 composed of 0 mol% and cyclohexanedimethanol unit 30 mol%, glass transition temperature 6
A polyester polymer D having a temperature of 8 ° C. was produced.

Production Example 6 Production of Polyester Polymer E In the same manner as in Production Example 1, 94 mol% of terephthalic acid units and 6 mol% of adipic acid units as dicarboxylic acid component units, and 7 mol of ethylene glycol units as diol component units.
9 mol%, cyclohexanedimethanol unit 21 mol%
Intrinsic viscosity 0.80, glass transition temperature 64
A polyester polymer E having a temperature of 0 ° C. was produced.

Production Example 7 Production of Polyester Polymer F In the same manner as in Production Example 1, 94 mol% of terephthalic acid units and 6 mol% of adipic acid units as dicarboxylic acid component units, and ethylene glycol units of 7 as diol component units.
A polyester polymer F composed of 6 mol%, cyclohexanedimethanol unit 21 mol% and diethylene glycol unit 3 mol% and having an intrinsic viscosity of 0.80 and a glass transition temperature of 63 ° C. was produced.

Example 1 Polyester polymers A and B-1 were mixed in the proportions shown in Table 1, dried and melt-extruded on a casting drum having a surface temperature of 35 ° C. using a T die at a temperature of 265 ° C.
A film having a thickness of 190 μm was formed. Next, this film was stretched 1.2 times in the machine direction at a temperature of 80 ° C. by a roll type longitudinal stretching machine, and then horizontally stretched 4.5 times at a temperature of 75 ° C. by a tenter. This stretched film,
A 10% heat relaxation treatment was performed at 70 ° C. to obtain a shrink film having a thickness of 40 μm. Table 2 shows the physical properties of this shrink film.

Examples 2, 3 and Comparative Examples 1, 2 After mixing the polyester polymers of the types and amounts shown in Table 1,
A film was formed in the same manner as in Example 1, and 15 ° C. from the apparent glass transition temperature of the polyester mixture,
1.2-fold longitudinal stretching, 4.5-fold transverse stretching and 10% thermal relaxation treatment were performed at a temperature higher by 10 ° C. and 5 ° C. to obtain a shrink film having a thickness of 40 μm. Table 2 shows the physical properties of these shrink films.

Examples 4, 5 and Comparative Example 3 After mixing the polyester polymers of the types and amounts shown in Table 1,
A film was formed in the same manner as in Example 1, and 15 ° C. from the apparent glass transition temperature of the polyester mixture,
1.2-fold longitudinal stretching, 4.5-fold transverse stretching and 10% thermal relaxation treatment were performed at a temperature higher by 10 ° C. and 5 ° C. to obtain a shrink film having a thickness of 40 μm. Table 2 shows the physical properties of these shrink films.

Comparative Example 4 Polyester polymers B-2 and D were mixed in the proportions shown in Table 1 and then formed into a film in the same manner as in Example 1 at 77 ° C. and 72 ° C.
1.2 times the longitudinal stretching, 4.5 times the lateral stretching at a temperature of ℃, 67 ℃,
A 10% heat relaxation treatment was performed to obtain a shrink film having a thickness of 40 μm. Table 2 shows the physical properties of this shrink film.

Comparative Examples 5 and 6 Polyester polymer E (Comparative Example 5) and polyester polymer F (Comparative Example 6) were formed into films in the same manner as in Example 1, and the glass transition temperature was 15 ° C. and 10 ° C., respectively.
1.2 times the longitudinal stretching, 4.5 times the lateral stretching,
A 10% heat relaxation treatment was performed to obtain a shrink film having a thickness of 40 μm. Table 2 shows the physical properties of these shrink films.

[0054]

[Table 1]

[0055]

[Table 2]

As is apparent from Table 2, the polyester shrink film of the present invention is excellent in low-temperature shrinkability and has a good finished appearance after mounting. Particularly, in the three-component polyesters of Examples 4 and 5, It is also good for difficult rectangular PET bottles. On the other hand, in the comparative example, the one having a heat shrinkage of 70 ° C. of less than 30% cannot be mounted due to insufficient low-temperature shrinkage. Is less than 60%, or the temperature dependence of the heat shrinkage near the shrinkage start temperature, that is, the low shrinkage temperature range is less than 8 ° C, distortion and wrinkles of the pattern may occur due to uneven shrinkage during mounting. The finished appearance is inferior.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoo Koyama 27408 Greensboro Natchez Trace 1715 (72) Inventor Shoichi Saya 1-18-1 Kyobashi, Chuo-ku, Tokyo Shiai Kasei Co., Ltd. (72 ) Inventor Kenji Yabe 1-18-1 Kyobashi, Chuo-ku, Tokyo Shiai Kasei Co., Ltd.

Claims (2)

[Claims] 1. A polyester 75-containing a dicarboxylic acid component unit mainly composed of (A) terephthalic acid and a mixed diol component unit consisting of 80 to 60 mol% of ethylene glycol and 20 to 40 mol% of cyclohexanedimethanol. 55 wt% and (B) terephthalic acid 90-75
Polyesters 25 to 4 composed of a mixed dicarboxylic acid component unit consisting of mol% and adipic acid 10 to 25 mol% and a diol component unit mainly composed of ethylene glycol
A film formed from a polyester composition containing 5% by weight of the adipic acid component units in the total dicarboxylic acid component units in an amount of 4 to 10 mol% and stretched in at least one direction by 1.5 to 8 times. The heat shrinkage rate in one direction is 7
A polyester shrink film which has a heat shrinkage of 30% or more at 0 ° C. and 60% or more at 100 ° C. and a heat shrinkage ratio in the direction perpendicular thereto of 10% or less at 100 ° C. 2. A polyester 75-containing a dicarboxylic acid component unit mainly composed of (A) terephthalic acid and a mixed diol component unit consisting of 80 to 60 mol% of ethylene glycol and 20 to 40 mol% of cyclohexanedimethanol. 55 wt% and (B) terephthalic acid 90-75
Polyester 25 composed of a mixed dicarboxylic acid component unit consisting of mol% and adipic acid 10 to 25 mol% and a diol component unit mainly composed of ethylene glycol
45% by weight, and (C) a dicarboxylic acid component unit mainly composed of terephthalic acid, relative to 100 parts by weight of a polyester mixture containing 4 to 10 mol% of adipic acid component units in all dicarboxylic acid component units. , Ethylene glycol 77-70 mol% and diethylene glycol 23-
A film formed from a polyester composition containing 2 to 10 parts by weight of a polyester composed of a mixed diol component unit of 30 mol% and stretched in at least one direction by 1.5 to 8 times. Direction heat shrinkage is 7
30% or more at 0 ° C and 60% or more at 100 ° C, and the thermal shrinkage in the direction perpendicular to that is 1 at 100 ° C.
Polyester type shrink film characterized by being 0% or less.