KR100427491B1 - Heat shrinkable polyester film - Google Patents

Abstract

It is a heat-shrinkable polyester film containing a copolymerization component, the density of which decreases due to heat shrinkage, and the tensile storage modulus E 'obtained by dynamic viscoelasticity measurement when the secondary transition is ideally terminated is 1.00 × 10 ⁸ (dyne / cm 2 ) Or a heat shrink polyester film having a shear storage modulus G 'of 3.00 × 10 ⁷ (dyne / cm 2) or more.

In particular, even under severe short-time shrinkage conditions, shrinkage stains are small, and heat resistance is excellent under high temperature conditions such as boiling treatment of bottles after filling and shrinkage, and high temperature filling of the contents.

Description

Heat shrinkable polyester film

The present invention relates to a heat-shrinkable polyester film suitable as a packaging material used for coating, binding, exterior, and the like. In particular, the present invention relates to a heat shrinkable polyester film of a kind which provides shrinkage stains and excellent heat resistance under severe conditions, and maintains a beautiful finish appearance stably.

Heat-shrinkable films are used for coating, binding, or exterior of various containers such as bottles (including glass and plastic bottles) and tubes and long articles (pipes, rods, wood, various rod-like bodies, etc.). It is becoming. For example, it is used to cover part or all of the cap, shoulder and body of a bottle for the purpose of marking, protecting, binding, and improving the value of a product. Furthermore, it is also used for the purpose of accumulating a plurality of boxes, bottles, plates, rods, notebooks, and the like in a package, or for packaging (skin package) by sticking the film to the packaged object (skin package). All of them utilize the shrinkage and shrinkage stress of the film, and polyvinyl chloride, polystyrene, polyethylene, rubber chloride, and the like are used as materials of such films. Usually, these films are molded into a tube shape, for example, a bottle or a pipe or the like is integrated, and then wrapped or bound by heat shrinkage.

However, since the film lacks heat resistance and none can tolerate the boiling treatment or the retort treatment at a high temperature, the film cannot be sterilized at a high temperature after being coated with the film. For example, when the retort treatment is performed, the conventional film breaks during the treatment. Moreover, the conventional film, for example, a polyvinyl chloride film, is bad in adhesiveness with ink, and is not suitable for the use, such as printing on a film. In addition, since vinyl chloride is poor in heat resistance, a gel-like material of a polymer or an additive is likely to form partly at the time of film formation, and pinholes are likely to occur on the printing surface because of this gel-like material. Since other conventional films also shrink with time after production, the printing pitch changes due to shrinkage, and high-precision printing cannot be performed.

For these, heat shrinkable films using polyester having excellent heat resistance, weather resistance and solvent resistance have been proposed. However, polyester heat shrinkable films also have insufficient heat shrinkage in a desired direction until now or are perpendicular to this direction. There was a problem such that the thermal contraction rate of can not be reduced. This problem can be solved by optimizing the copolymerization composition of the polyester resin as a raw material, for example, as disclosed in Japanese Patent Application Laid-Open No. 63-156833, but the shrinkage rate is too fast even in the films obtained by these methods. However, there is a disadvantage in that shrinkage stains in which the nonuniform temperature distribution generated in the shrinkage process is sensitively reflected are generated. In addition, after coating the container, when performing sterilization treatment such as a boil treatment or a retort treatment at a high temperature, the film does not break but has a problem that the film is stretched. In this regard, Japanese Patent Laid-Open No. Hei 6-31806 solves the problem by producing a film exhibiting a static relaxation phenomenon characteristic, but it is insufficient to maintain the finish appearance and stability of the heat shrinkable film.

On the other hand, the heat shrink process for attaching the heat shrink film to the adherend has recently been diversified. For example, the wet heat process, the dry heat process, the low temperature shrink process, the high-speed mounting process, and the combination process thereof have been continuously performed. Therefore, in the heat shrink film, the invention of the heat shrink film that can cope with a very severe shrinking condition in a wide range can be achieved. It is needed.

In order to solve the problems of the prior art in the polyester-based heat shrink film, the present invention provides a film that maintains the finish appearance and its stability even in a shrinkage condition which is simplified and accelerated, especially in a film in which density decrease occurs due to heat shrink. It is an object to provide an ester heat shrink film.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the measurement example of storage stiffness G 'and loss stiffness G "obtained by dynamic viscoelasticity measurement about the unstretched film of polyethylene naphthalate (dynamic viscoelasticity when a secondary transition is ideally completed. It is a figure for calculating the shear storage modulus G 'obtained by the measurement).

(A) is a figure which shows a 4-element model as a viscoelastic model of a heat-shrink film, (b) is an estimate using the film after shrinkage in the shrinkage temperature area | region with the value of each element constant.

3 is a diagram illustrating a generation model of thermal contraction stress.

FIG. 4 is a graph of the results and actual measurement results of the semi-empirical simulation of the shrinkage stress experiment using the model of FIG. 3.

Fig. 5 is a diagram showing another example of measurement of storage stiffness G 'and loss stiffness G " obtained by dynamic viscoelasticity measurement.

Fig. 6 is a diagram showing another measurement example of storage stiffness G 'and loss stiffness G " obtained by dynamic viscoelasticity measurement.

7 is a reference diagram showing a measurement example of storage modulus E 'and loss modulus E "obtained by dynamic viscoelasticity measurement.

8 is a reference diagram showing an example of measuring storage modulus E 'and loss modulus E "obtained by dynamic viscoelasticity measurement. FIG. 9 is Progress in Organic Coatings, 11 (1983) p139 to 165, A. Tooussaint et L. Dhont. Figure 147, Figure 4, shows an example of known measurement results.

The heat shrink polyester film of this invention has the following structures.

(1) A heat-shrinkable polyester film containing a copolymerization component, the density of which decreases due to heat shrinkage, preferably a heat shrinkable polyester film having a heat shrinkage ratio in one direction of 30% or more at 100 ° C, and the secondary transition is ideally A heat-shrinkable polyester film having a tensile storage modulus E 'of 1.00 × 10 ⁸ (dyne / cm ² ) or more obtained by dynamic viscoelasticity measurement carried out in either direction when finished.

(2) A heat-shrinkable polyester film containing a copolymerization component, the density of which decreases due to heat shrinkage, preferably a heat shrinkage polyester film having a heat shrinkage ratio in one direction of 30% or more at 100 ° C, and the secondary transition is ideally A heat-shrinkable polyester film having a shear storage modulus G 'obtained by dynamic viscoelasticity measurement performed in either direction when finished, at least 3.00 × 10 ⁷ (dyne / cm ² ).

(3) At least one monomer selected from the group consisting of terephthalic acid and ethylene glycol, and at least one selected from neopentyl glycol, bisphenol-based compound, 2,6-naphthalenedicarboxylic acid, cyclohexanedimethanol, and 1 The heat-shrinkable polyester film as described in (1) or (2) which consists of a polyester resin composition containing 1 or more types of monomers chosen from 4-butanediol, adipic acid, and sebacic acid.

(4) As a polyethylene terephthalate and the monomer component, as a polyester component and a monomer component containing neopentylglycol, a bisphenol type compound, 2, 6- naphthalenedicarboxylic acid, and at least 1 sort (s) of monomer selected from cyclohexane dimethanol. The heat shrink polyester film as described in (1) or (2) which consists of a polyester resin composition which contains as a main component the polyester containing 1 or more types of monomers chosen from 1, 4- butanediol, adipic acid, and sebacic acid.

In addition, in this invention, a film contains what is called a sheet | seat.

The heat-shrinkable polyester film of the present invention having the properties of the above (1) and (2) alone, or both the properties of (1) and (2) is excellent in the finish appearance after shrinkage and its stability.

In the present invention, the tensile storage modulus E 'and the shear storage modulus G' obtained by dynamic viscoelasticity measurements performed in either direction when the secondary transition is ideally terminated are defined as follows. In other words, the measured storage modulus E 'or storage stiffness G' is plotted on the horizontal axis, and the loss modulus E "or loss modulus G" is plotted on the vertical axis. At this time, the full scale of the vertical axis is taken to be one digit smaller than the full scale of the horizontal axis, plotted in linear scale, and the graphs are drawn in descending order of temperature. Looking at the entire curve, the right side is the low temperature side and the left side is the high temperature side, and the large and convex acid is the secondary transition. In the left end of the peak, the loss modulus E "or the loss stiffness modulus G" of 1/2 or less of the maximum value is approximated to the straight line at the steepest slope as much as possible, and the storage modulus E 'is the horizontal axis. Or the tensile storage modulus E 'obtained by the dynamic viscoelasticity measurement performed in either direction when the secondary transition is ideally terminated, with the section lowered on the axis of the storage stiffness G' being ideally terminated. Or the shear storage modulus G '. 1 and 5 to 8 show examples of graphs.

The heat-shrinkable polyester film of the present invention (sometimes abbreviated to the following film) is not particularly limited as long as it satisfies the above physical properties, but the composition, structure, and manufacturing method thereof are not particularly limited. Control of the state, its distribution, molecular weight, branched chain introduction into the main chain, crosslinking state, degree of molecular chain entanglement, mixed state in the case of containing two or more kinds of resins or components can be effectively used. Such a heat-shrinkable polyester film is, in addition to the setting of the constituents, for example, the introduction of a cross-linking structure such as polyester-melamine, epoxy-polyamide, urethane crosslinking, polyester, constituent material thereof, crystalline, amorphous, semi-crystalline It can be obtained by mixing or copolymerizing a polymer, heat treatment thereof, addition of a filler, or orientation treatment by stretching of a film, or performing appropriate heat setting. 1, 5 and 6 show measurement examples in which the tensile storage modulus E 'or the shear storage modulus G' is changed by the above control.

1 is an unstretched film of polyethylene naphthalate, and FIG. 5 is an unstretched film of coPEs-A used in Example 2, which curve 1 is described later, and NPG-coPET used in Example 1, which curve 2 is described later. The unstretched film of resin in which the coPEs-A is blended in a weight ratio of 50:50, and the curve ③ is quenched after the heat treatment of the unstretched film of ②, FIG. 6 shows SA-coPET used in Example 1 to be described later. It is a measurement result regarding the heat processing of an unstretched film. 7 and 8 are shown as a reference example. FIG. 7 is a film of a resin which is blended with polyurethane and nitrocellulose in a weight ratio of 65:35, and added with 70% by weight of iron oxide (each curve has a different dispersion state of iron oxide particles). It is a measurement result regarding the film of resin which mix | blended polyurethane block so that it may become 30 weight% of polyurethane, and dried. FIG. 9 is a known figure which shows that crosslinked structures, such as polyester-melamine and epoxy-polyamide, are effective for this invention. The measurement result.

The polyester resin composition which is the raw material which forms the heat shrink polyester film of this invention consists of polyester comprised by the dicarboxylic acid component and the diol component as a main component.

As the dicarboxylic acid component, in addition to the terephthalic acid constituting the ethylene terephthalate unit, any of aromatic dicarboxylic acid, aliphatic dicarboxylic acid and alicyclic dicarboxylic acid can be used. As aromatic dicarboxylic acid, Benzene dicarboxylic acids, such as isophthalic acid, orthophthalic acid, 5-tert- butyl isophthalic acid; Naphthalenedicarboxylic acids, such as 2,6-naphthalenedicarboxylic acid; Dicarboxybiphenyls such as 4,4'-dicarboxydiphenyl and 2,2,6,6-tetramethylbiphenyl-4,4'-dicarboxylic acid; 1,1,3-trimethyl-3-phenylindene-4,5-dicarboxylic acid and its substituents; 1,2-diphenoxyethane-4,4'-dicarboxylic acid and substituents thereof. As aliphatic dicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, pimelic acid, suberic acid, undecanoic acid, dodecanedicarboxylic acid Acids, brassylic acid, tetradecanedicarboxylic acid, thapsic acid, nonadecandicarboxylic acid, docoic acid dicarboxylic acid, and substituents thereof 4,4'-dicarboxycyclohexane And substituents thereof.

As the diol component, there are ethylene glycol constituting the polyethylene terephthalate unit, and any of aliphatic diols, alicyclic diols and aromatic diols can be used. Aliphatic diols include diethylene glycol, propylene glycol, butanediol, 1,6-hexanediol, 1,10-decanediol, neopentyl glycol, 2-methyl-2-ethyl-1,3-propanediol, 2-diethyl- 1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, and the like. Examples of the alicyclic diols include 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol. As aromatic dicarboxylic acid, ethylene oxide adducts of bisphenol-based compounds such as 2,2-bis (4'-β-hydroxydiethoxyphenyl) propane and bis (4'-β-hydroxyethoxyphenyl) sulfone ; Polyalkylene glycols such as xylene glycol, polyethylene glycol and polypropylene glycol.

The polyester used in the present invention usually contains a combination of at least one acid component and / or at least one diol component, whereby the properties as a heat shrinkable film can be improved. The kind of monomer components used in combination and their monomer ratios are appropriately selected based on desired film properties, economics and the like.

The polyester resin composition for forming the heat-shrinkable polyester film of this invention is comprised from 1 type (s) or 2 or more types of polyesters as above as a main component. Preferably at least one monomer selected from the group consisting of terephthalic acid and ethylene glycol as a monomer component, and at least one selected from neopentyl glycol, a bisphenol-based compound, 2,6-naphthalenedicarboxylic acid, cyclohexanedimethanol, and 1, It is preferable to contain at least one monomer selected from 4-butanediol, adipic acid and sebacic acid.

Moreover, it is a polyester and monomer component containing polyethylene terephthalate and at least 1 sort (s) of monomer chosen from neopentylglycol, a bisphenol type compound, 2, 6- naphthalenedicarboxylic acid, and cyclohexane dimethanol as a monomer component. Polyester resin composition containing, as a main component, a polyester containing at least one monomer selected from 4-butanediol, adipic acid and sebacic acid, that is, from a polyester resin composition comprising three different monomer configurations If formed, it is preferable to independently control other resin characteristics.

The manufacturing method of the polyester used for the heat-shrinkable polyester film of this invention is not specifically limited, It can be manufactured by the method of a conventionally well-known method. For example, the direct esterification method which directly reacts dicarboxylic acid and diol; The transesterification method etc. which make dicarboxylic acid dimethyl ester and a diol react are mentioned. The preparation may be carried out by any of batch and continuous methods.

The polyester resin composition used in the present invention contains one or more polyesters, but in the case of two or more polyesters, the copolymerized polyester having two or more dicarboxylic acid components and / or diol components and one component each You may select 2 or more types of homopolyesters within the range in which the action of this invention is expressed. In general, copolyesters have a low melting point, which makes them difficult to handle during drying. Therefore, homopolyesters (polyethylene terephthalate, polyethylene naphthalate, poly (1,4-cyclohexenedimethylene terephthalate), etc.) It is preferable to mix and use a copolyester.

The polyester resin composition used for this invention contains various additives in the range which does not inhibit the effect | action of this invention other than the said polyester as needed. As an additive, For example, lubricants, such as a titanium dioxide, particulate silica, kaolin, calcium carbonate; Void expression agents such as polypropylene, polystyrene, and polymethylpentene; Antistatic agent; Anti-aging agents; Sunscreens; Coloring agents (paints, etc.); various fillers; Various pigments are mentioned. Among them are additives that reinforce the action of the present invention.

The heat-shrinkable polyester film of this invention is obtained by forming the said polyester resin composition into a film form by a well-known method (for example, extrusion method, calender method), etc .. The shape of the film is not particularly limited, and may be, for example, planar or tubular. When the obtained film is shrunk only in the uniaxial direction, for example, it is stretched in the range of 2.5 times to 7.0 times, preferably 3.0 times to 6.0 times, in one predetermined direction (main stretching direction) under the predetermined conditions described below. In the direction perpendicular to this direction, the film is stretched in the range of 1.0 to 2.0 times, preferably 1.1 to 1.8 times. The order of this stretching may be any one. Stretching in the main stretching direction is performed to obtain high heat shrinkage in that direction. When the elongation in the perpendicular direction exceeds 2 times, the heat shrinkability in the direction perpendicular to the main contraction direction becomes excessively large, and the finish at the time of thermal contraction tends to be uneven in the waving state.

The stretching method is not particularly limited, and can be usually carried out by a known method, for example, a roll stretching method, a long gap gap stretching method, a tenter stretching method, a tubular stretching method, or the like. In any of these methods, the stretching can be carried out sequentially, biaxial stretching, simultaneous biaxial stretching, uniaxial stretching, and a combination thereof. In the biaxial stretching, stretching in the longitudinal and transverse directions may be simultaneously performed, but sequential biaxial stretching in which one direction is performed first is effective, and the longitudinal and transverse order may be any first.

Preferably, the stretching is carried out in the following process. For example, first, the film is preheated at a temperature higher than the average glass transition temperature (Tg) of the polymers constituting them, for example, Tg + 80 ° C or lower. When preheating in the above-described temperature range during the main direction stretching (main contraction direction), thermal contraction in a direction perpendicular to this direction can be suppressed.

It is preferable that heat setting is performed at the time of these extending | stretching. For example, after extending | stretching, it is recommended to pass through the heating zone of 30 degreeC-150 degreeC for about 1 second-30 second. In addition to controlling the orientation arbitrarily by this heat setting treatment, the crystallization ratio in the material is also controlled. Therefore, desired physical properties can be appropriately controlled by the ratio and distribution of crystallization.

Since the heat-shrink polyester film of this invention considers the dynamic viscoelasticity of a polymer, the film which has a desired property is obtained by controlling the specific phenomenon which exists by changing the solid structure in a material. The proof is as follows.

As the simplest viscoelastic model of the heat shrinkable film, a four-element model in which the Maxwell model and the Voigt model are connected in series as shown in FIG. 2 (a) can be used (for example, Wayne K. Shin.Polymer). Engineering and Science, July 1994, Vol 34, No. 14, P1121-1128. and M. Trznadel, et. Al. Polymer, 1985, Vol 26, July P1019-1024.).

In this model, the viscosity of the dashpot is lowered by raising the temperature. When the 4-element model is stretched and quenched at a high temperature under these conditions, energy for contraction is stored and fixed in the spring of the vogue model part. At this time, since the dash port of the Maxwell model part is also displaced small, they become a loss when stretching. When the stretched four-element model is rapidly heated up to the stretching temperature condition, the viscous of the dash port of the bog model part decreases drastically and the spring of the bog model part contracts. When the free end contracts, the vogue model portion contracts and breaks, and the contraction phenomenon is terminated. However, the contraction actually contracts and contacts the object at some point. Next, the fixed end contracts (relieves shrinkage stress). The mitigation process has also used the Maxwell model division's dashport. This phenomenon can be measured by thermally jumping the shrinkage stress experiment, that is, the shrinkage film formed by the fixed end, and plotting the resulting shrinkage stress over time. In order to apply the 4-element model to this shrinkage stress experiment, the value of each element constant was estimated using the film after shrinkage in the shrinkage temperature range. Fig. 2 (b) shows that the Maxwell part was estimated by the Alfrey method for measuring the response distortion due to the short-wave stress, and the shrinkage rate-time plot of the heat shrink film at the same temperature was also estimated. . The obtained values are shown in Table 2. Substituting this value into the equation of FIG. 3 results in a semi-empirical reproduction of the shrinkage stress experiment and the measured value is shown in FIG. 4. As a result, the film having good thermal stability after shrinkage without causing shrinkage stains not only had a small relaxation of the shrinkage stress reproduced semi-empirically, but also a decrease in the measured value. This fact indicates that films that do not cause shrinkage stains have a low viscous behavior when the dashwell of the Maxwell model section is hot in the four-element model, or disappear due to a special mechanical factor involved in the dashport section.

There are many ways to express polymers as relatively simple equivalent dynamics models, including four-element models. The method used in the present invention is a method of plotting the storage modulus (or stiffness) and the loss modulus (or stiffness or viscosity) obtained by the dynamic viscoelasticity measurement, respectively, on the real axis and the imaginary axis. This plot is similar to the Cole-Cole plot in genetic loss measurements and has long been known in viscoelastic research. In the dielectric loss measurement, the real axis and the virtual axis use the measurement frequency as a parameter, while in dynamic viscoelasticity, the temperature is a parameter. However, polymer science claims that there is a 1: 1 conversion of frequency and temperature. In the genetic loss measurement, the arc side and the lemniscate side for expressing the individuality of the object to be measured are uniformly established, but in the case of dynamic viscoelasticity, methods for expressing the individuality of the polymer have been performed separately (for example, Progress). in Organic Coatings (11 (1983) 139-165 A. Toussaint et L. Dhont).

Applying the plot of dynamic viscoelasticity measurements to a heat shrinkable polyester film, the plot curve of the film, which keeps the finish stable without causing any kind of shrink stain, extends the tip of the convex curve upward in most cases. One end did not pass through the origin of the complex plane. This is equivalent to the small contribution to the large deformation of the dashwell of the Maxwell section, which is the result of the reconstruction experiment of the four element model. For example, it has the characteristics of the Zener model and the biparabolique limite model of the said document. The heat shrinkable polyester film of the present invention is similar to the model described above.

Regarding the upper limit of each parameter, the value at the end of the secondary transition ideally needs to be less than one-third of the value (free state) before the secondary transition occurs, and if it is larger than that, it inhibits heat shrinkage behavior. .

Because heat shrinkage is a variation of the type of thermodynamic secondary transition, it is important to know and control the thermal and mechanical behavior of the polymer in the transition region, especially in the middle. By the method of clarifying the start and end of the secondary transition of the polymer as described above, it can be seen semi-empirically that the behavior of the secondary transition is suitable for the finishing of the heat-shrinkable film and its stability.

The effect of the secondary transition behavior on the state after contraction is considered through the following. That is, the phenomenon that the G 'is large in the region of large interlocking properties of the polymer chains after the second transition is well found in, for example, many fillers, but these include fillers or polymers around the fillers for shearing, It is said to display the same real elasticity as a rigid body and an elastic body, and it can be seen as a real resistance to the flow deformation called shear. It is believed that this causes the thermal transition of the secondary transition by the movement of the polymer chain and functions as the strength of the waist when it contracts, and as a result, the uniformity of the thermal contraction is improved, so that it is not affected by the temperature stain during contraction. On the other hand, when E 'is large in the second half of the second transition, the tensile stress generated by thermal contraction is resisted according to a certain amount of real elasticity, so that excessive shrinkage is partially suppressed even under high speed shrinkage conditions, and stress relaxation is again. Is considered to be low and stable.

Hereinafter, the present invention will be described in more detail using experimental examples and examples, but the present invention is not limited thereto.

Experimental Example

1. Test Method

(1) heat shrinkage rate measurement

About the heat shrink polyester film of Examples 1-5 and Comparative Examples 1-3, the direction which a film shrinks was made into the long side, and it cut | disconnected so that it might become 15 mm in width. Mark marks were recorded at intervals of 200 mm in this long side direction. This sample was hold | maintained in the gear oven of predetermined temperature, it was taken out after 1 minute, and the amount of change of the distance between marks is measured. The percentage with respect to the original length (200 mm) of this change was made into thermal contraction rate (%).

(2) Density measurement

About the heat-shrinkable polyester films of Examples 1-5 and Comparative Examples 1-3, 10 samples which cut each square 3 mm square each of the unheated thing and the heat-shrinkage heated on a 90 degreeC potplate for 1 minute are prepared, respectively. It was. This sample was measured at 30 ° C. in a density gradient tube using calcium nitrate solution based on JIS K-7112.

(3) Dynamic viscoelasticity measurement

The dynamic viscoelasticity measurement was performed about the heat shrink polyester film of Examples 1-5 and Comparative Examples 1-3. Using DVE Leospectra-DVE-V4 manufactured by Rheology, sine wave distortion, continuous vibration, frequency 110 Hz, measurement temperature -30 ° C to 150 ° C, and heating rate 2 ° C / min are common conditions. In the tensile mode measurement, the heat shrinkable film was cut into 5 mm x (20 mm + holding part) in the MD direction or the TD direction of the longitudinal direction, and placed in the inlet port to measure the dynamic viscoelasticity at a constant load of 20 g and an amplitude displacement of 2 µm. . In the case of the shear mode measurement, two bundles of five pieces cut into 8 mm x 10 mm cut out in the MD direction or the TD direction of the heat shrinkable film were prepared, placed in a shear jig, and measured at an amplitude displacement of 0.2 µm.

Regarding the obtained values, the storage modulus E 'or the storage rigidity G' is plotted on the horizontal axis, and the loss modulus E "or the loss modulus G" on the vertical axis. At this time, the full scale of the vertical axis was one digit smaller than the full scale of the horizontal axis, plotted on a linear scale, and plotted in the order of the lowest temperature. In the whole curve, the right side is the low temperature side, the left side is the high temperature side, and the large convex acid is the secondary transition. Also, the portion of continuous forging change below the maximum value of the loss modulus E "or the loss stiffness G" in the left end portion of the convex acid is approximated to the straight line at the steepest slope as much as possible, and the storage modulus E 'which is the horizontal axis is stored. Tensile storage modulus E 'or shear storage modulus G' was determined by making the section lowered on the axis of stiffness G 'ideally at the end of the secondary transition.

(4) shrink stain

The heat-shrinkable polyester films of Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to metal cooking printing, tube-shaped into cylinders, and then put on a PET bottle of 1.5 L and passed through a shrink tunnel. . Shrink tunnel setup is a more stringent condition for finishing. Dry heat type 130 degreeC, 5 second, 1 zone, it carried out by bottle non-rotation. As a determination of the finishing state, shrinkage stains and color stains were observed by the naked eye according to the following criteria.

◎: 1 or less cracks per sample

○: 2 to 3 cracks per sample

×: 4 or more cracks stain per sample

(5) Boyle treatment

About the heat-shrinkable polyester film of Examples 1-5 and Comparative Examples 1-3, the film was made into the shrinkage label, it was covered in the bottle which put water, and it shrink | contracted in 80 degreeC hot water. These were again immersed in the hot water of 80 degreeC for 30 minutes, and the sagging state of the label was visually judged. These were done on 10 samples.

◎: 0 out of 10 samples of sagging and wrinkles

○: sagging, wrinkles 1-2 of 10 samples

×: sagging and wrinkles are three or more of 10 samples

2. Test result

Table 1 shows the test results of the above (1) to (5).

Test subject Polyester composition Heat setting temperature (℃) Test result Component 1 (% by weight) Component 2 (% by weight) Component 3 (% by weight) Heat Shrinkage (%) Density (g / cm 3) Dynamic viscoelasticity Shrinkage Boyle treatment Before contraction After contraction E '× 10 ⁸ (dyne / ㎠) G '× 10 ⁷ (dyne / ㎠) Example 1 PET5 NPG-coPET85 SA-coPET10 93 65 1.3008 1.2946 2.67 5.10 ◎ ◎ Example 2 PET5 NPG-coPET85 coPEs-A10 93 68 1.3010 1.2951 2.71 5.54 ◎ ◎ Example 3 PET5 CHDM-coPET85 SA-coPET10 93 63 1.2924 1.2900 2.80 4.48 ◎ ◎ Example 4 PET5 CHDM-coPET85 coPEs-A10 92 66 1.2932 1.2903 2.75 5.14 ◎ ◎ Example 5 PET5 NPG-coPET85 SA-coPET10 70 72 1.3131 1.2921 1.02 3.13 ○ ○ Comparative Example 1 PET5 NPG-coPET85 SA-coPET10 20 75 1.3132 1.2925 0.850 2.40 × × Comparative Example 2 PET5 NPG-coPET85 coPEs-A10 20 73 1.3134 1.2929 0.910 2.82 × × Comparative Example 3 NPG-coPET100 - - 40 70 1.3615 1.2915 To 0 1.46 × ×

* Density is average value

Example

Example 1

Polyester terephthalate (PET), Copolyethylene terephthalate (NPG-coPET) copolymerized with 30 mol% neopentyl glycol in the glycol component, Copolyethylene terephthalate (SA- copolymerized with 52 mol% sebacic acid in dicarboxylic acid coPET) were mixed at a weight ratio of 5:85:10, respectively, and melt-extruded at 290 ° C using a polyester resin composition containing 0.05 part by weight of silica having an average particle diameter of 2.4 µm to obtain a sheet having a thickness of 190 µm. The unstretched sheet was preheated at 120 ° C. for 6 seconds, and then stretched 4.8 times in a predetermined direction at a temperature of 70 ° C. After extending | stretching, heat setting was carried out at 93 degreeC for 5 second, maintaining a tension state, it cooled to 40 degreeC and obtained the heat shrink polyester film of 40 micrometers in thickness.

Example 2

Instead of SA-coPET, a polyester polycondensed using 65 mol% of terephthalic acid, 10 mol% of isophthalic acid, 25 mol% of adipic acid, and 100 mol% of 1,4-butanediol as a glycol component Except having used coPEs-A), it carried out similarly to Example 1, and obtained the heat shrink polyester film of 40 micrometers in thickness.

Example 3

A heat shrinkable polyester film having a thickness of 40 µm in the same manner as in Example 1 except that polyethylene terephthalate (CHDM-coPET) copolymerized to 35 mol% of cyclohexanedimethanol as a glycol component was used instead of NPG-coPET. Got.

Example 4

Instead of NPG-coPET, CHDM-coPET was used, and the heat-shrinkable polyester film having a thickness of 40 µm was obtained in the same manner as in Example 2 except that the heat setting temperature was 92 ° C.

Example 5

Except having made the heat setting temperature into 70 degreeC, it carried out similarly to Example 1, and obtained the heat shrink polyester film of 40 micrometers in thickness.

Comparative Examples 1 and 2

Except having made the heat setting temperature into 20 degreeC, it carried out similarly to Example 1, 2, and obtained the heat shrink polyester film of 40 micrometers in thickness.

Comparative Example 3

Except having used NPG-coPET only as a polyester raw material to be used, and setting the heat setting temperature to 40 degreeC, it carried out similarly to Example 1, and obtained the heat shrink polyester film of 40 micrometers in thickness.

The heat-shrinkable polyester film of the present embodiment has little shrinkage stain even under strict short-time shrinkage conditions, and is excellent in heat resistance under temperature conditions such as bottle treatment and high temperature filling of contents after shrink fitting to a bottle, and stabilizes a beautiful finish appearance. Keep it. Therefore, it is used suitably for the purpose of coating | covering, binding, and exterior.

Element constant measurement example G ₁ G ₂ η ₂ η ₁ Polystyrene Shrink Film 0.473 0.500 89.8 5.91 Vinyl chloride series shrink film 0.0397 0.0676 0.804 7.00 Polyester series shrink film 0.0368 0.128 0.125 6.03

Unit: (mmkgsec), 90 ℃

Claims (4)

delete delete As the monomer component, at least one monomer selected from neopentylglycol, bisphenol-based compound, 2,6-naphthalenedicarboxylic acid, cyclohexanedimethanol, including terephthalic acid and ethylene glycol, and 1,4-butanediol, It is a polyester resin composition comprising a copolymerization component containing at least one monomer selected from adipic acid and sebacic acid, and the tensile storage modulus E 'obtained by dynamic viscoelasticity measurement at the end of the secondary transition is 1.00 × 10. ^A heat-shrinkable polyester film having ⁸ (dyne / cm 2) or more and a shear storage modulus G 'of 3.00 × 10 ⁷ (dyne / cm 2) or more. Polyester containing polyethylene terephthalate and at least 1 sort (s) of monomer chosen from neopentylglycol, a bisphenol type compound, 2, 6- naphthalenedicarboxylic acid, cyclohexane dimethanol as a monomer component, and 1,4 as a monomer component -Tensile storage modulus E obtained by dynamic viscoelasticity measurement, consisting of a polyester resin composition containing, as a main component, a polyester containing at least one monomer selected from butanediol, adipic acid, and sebacic acid as a main component. A heat-shrinkable polyester film having a value of '1.00 × 10 ⁸ (dyne / cm 2) or more and a shear storage modulus G' of 3.00 × 10 ⁷ (dyne / cm 2) or more.