Measurement method for heat shrinkage rate of polyester shrink film

Abstract

The present invention provides a method for measuring the thermal shrinkage rate of polyester shrink film, which can be performed quickly and accurately using motion capture. The method for measuring the thermal shrinkage rate of a polyester shrink film using motion capture includes the following steps (a) to (e). That is, the method includes the steps of (a) setting two measurement positions in the main shrinkage direction and measuring the distance between the two measurement positions as L1, (b) attaching markers of an inertial measurement unit to the measurement positions, (c) heating at a specified temperature for a specified time as specified thermal shrinkage conditions to cause thermal shrinkage, (d) measuring the distance between the two measurement positions after thermal shrinkage as L'1 using motion capture, and (e) calculating the thermal shrinkage rate of the polyester-based shrink film based on a specified formula.

Description

[Technical field]

[0001] The present invention relates to a method for measuring the thermal shrinkage rate of a polyester shrink film. More specifically, the present invention relates to a method for measuring the thermal shrinkage rate of a polyester shrink film, which can measure the thermal shrinkage rate quickly and accurately by using motion capture. [Background technology]

[0002] Conventionally, shrink films have been widely used as base films for labels on PET bottles, etc. In particular, polyester resins are widely used due to their excellent transparency and strength. These shrink films are thermally shrunk by passing through a tunnel that generates hot air or steam, and then attached to the container, but shrinkage differences (unevenness) may occur during thermal shrinkage, resulting in wrinkles and uneven coloring. In view of this, various heat-shrinkable polyester films have been proposed to prevent wrinkles and color unevenness caused by shrinkage differences (unevenness) that occur during heat shrinkage.

[0003] For example, a heat-shrinkable polyester film has been proposed in which the proportion of alcohol components other than ethylene glycol is controlled, or the amount of naphthalenedicarboxylic acid component or the amount of alkali metal salt of sulfobenzenedicarboxylic acid in the total acid components is strictly controlled (see Patent Document 1). More specifically, the polyester resin is characterized in that the proportion of acid components other than terephthalic acid in the total acid components (A mol %) and the proportion of alcohol components other than ethylene glycol in the total alcohol components (B mol %) are in the range of 5 mol %≦A+B≦40 mol %, and the total acid components contain 1 to 30 mol % of a naphthalenedicarboxylic acid component and 0.3 to 3 mol % of an alkali metal salt of sulfobenzenedicarboxylic acid. The heat shrinkage rate of the polyester film is preferably 5% or more in the longitudinal direction of the film when immersed in hot water at a temperature of 60°C for 60 seconds, and 30% or more when immersed in hot water at a temperature of 80°C for 60 seconds.

[0004] In addition, a heat-shrinkable polyester film has been proposed in which the amount of amorphous components in the total polyester resin components is strictly controlled, and the hot water heat shrinkage rate at 80°C and 90°C in the longitudinal direction of the film and the hot water heat shrinkage rate at 90°C in the width direction of the film are limited (see Patent Document 2). More specifically, it is a heat-shrinkable polyester film that contains ethylene terephthalate as a main component and one or more monomer components that can become amorphous components in the entire polyester resin component, the total of which is 15 mol % or more. The hot water shrinkage rate of the polyester film in the longitudinal direction of the film is 30% or more at a treatment temperature of 80°C for a treatment time of 10 seconds, and 40% or more at a treatment temperature of 90°C for a treatment time of 10 seconds, and the hot water shrinkage rate in the width direction of the film is 10% or less at a treatment temperature of 90°C for a treatment time of 10 seconds.

[0005] Also, a heat-shrinkable polyester film has been proposed in which the shrinkage rate in one direction and the heat shrinkage rate in the direction perpendicular thereto are specified, and the average heat shrinkage rate coefficient in a temperature range of 70 to 120°C is set within a predetermined range (see Patent Document 3). More specifically, it is a heat-shrinkable polyester film that is a homopolymer of polyethylene terephthalate or a copolymer containing a dicarboxylic acid component other than terephthalic acid, and / or a diol component other than ethylene glycol, and / or an oxycarboxylic acid, etc. The thermal shrinkage rate in at least one direction is 30% or more, and the average thermal shrinkage rate coefficient in at least that direction within a temperature range of 70 to 120°C is in the range of 0.1 to 0.5% / sec·°C.

[0006] Also, a shrink label has been proposed in which the maximum heat shrinkage rate measured under specific conditions is specified (see Patent Document 4). More specifically, it is a heat-shrinkable shrink label that has at least one film layer containing a polylactic acid polymer as an essential component, and a printed layer. The heat shrinkage rate in the main orientation direction after 1 second in 75°C warm water is 3 to 23%, and the heat shrinkage rate in the main orientation direction after 10 seconds at 90°C is 40 to 84%. Alternatively, the maximum heat shrinkage rate in the main orientation direction in 75°C warm water is 7 to 40% / sec, and further, the heat shrinkage rate in the main orientation direction at 90°C for 10 seconds is 40 to 84%. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 08-027259 A (Claims, etc.) [Patent Document 2] JP 2007-016120 A (Claims, etc.) [Patent Document 3] JP 8-323859 A (Claims, etc.) [Patent Document 4] JP 2008-1098 A (Claims, etc.) Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the heat-shrinkable films described in Patent Documents 1 and 2, although the heat shrinkage rate at a specified temperature and in a specified shrinkage direction is limited to within a specified range, it is necessary to immerse the film in hot water and then remove it from the hot water before measurement, which can easily cause uneven heat distribution and large variations in the measured values. Therefore, it is difficult to obtain a polyester film having a desired heat shrinkage rate from a polyester film having a heat shrinkage rate measured in this manner, and there are cases in which the heat shrinkage rate characteristics cannot be controlled quickly and accurately. Therefore, particularly in the case of PET bottles in which the bottle diameter of the body is not uniform and the horizontal cross-sectional shape of the body is not circular in some parts and has a complex shape, the heat shrinkability is likely to be non-uniform, making it extremely difficult to prevent the occurrence of fine wrinkles.

[0009] In addition, in the heat shrinkable film described in Patent Document 3, although the amount of change in the heat shrinkage rate with respect to time is specified, the heat shrinkage rate coefficient (% / (sec·°C)) averaged before and after heat shrinkage is specified, and there was no intention to measure the heat shrinkage rate (mm / sec) from before heat shrinkage until a specified time, let alone the maximum value. For this reason, it was not possible to accurately measure the heat shrinkage speed (mm / sec) at the timing when the heat shrinkable film undergoes large changes in a short period of time during heat shrinkage.

[0010] Furthermore, in the shrink label described in Patent Document 4, the heat shrinkage rate (%) 1 second after the start of heat shrinkage is specified, but this is a heat shrinkage rate that is time-limited, and no intention is given to shrink labels that have different timing of heat shrinkage. Furthermore, although the maximum heat shrinkage speed (% / sec) is also mentioned, this is a measurement of the actual instantaneous heat shrinkage speed when measured at 0.1 second intervals, and there was no intention to measure the maximum value of the heat shrinkage speed (mm / sec) from before heat shrinkage until a specified time. Therefore, when converted into a maximum value of the heat shrinkage speed from before heat shrinkage until a predetermined time, the range is very narrow.

[0011] Therefore, the inventors of the present invention discovered that by using motion capture to measure the thermal shrinkage rate in the main shrinkage direction, etc. through specified steps (a) to (e) and controlling the value, the thermal shrinkage characteristics can be measured quickly and accurately, and thus completed the present invention. In other words, an object of the present invention is to provide a simple method for measuring the thermal shrinkage rate of a polyester shrink film quickly and accurately using a predetermined motion capture. [Means for solving the problem]

[0012] According to the present invention, there is provided a method for measuring the thermal shrinkage rate of a polyester-based shrink film using motion capture, the method comprising the following steps (a) to (e), thereby solving the above-mentioned problems. Step (a): A step of setting two measurement positions in the main shrinkage direction of a polyester shrink film as a measurement object, and measuring the distance between the two measurement positions as L1. Step (b): Providing a predetermined marker at each of the two measurement positions. Step (c): A step of heating the polyester shrink film at a predetermined temperature for a predetermined period of time under predetermined heat shrinkage conditions to cause heat shrinkage. Step (d): A step of measuring the distance of a predetermined interval after thermal shrinkage, designated as L'1, using motion capture. Step (e): A step of calculating the heat shrinkage rate in the main shrinkage direction of the polyester shrink film as the heat shrinkage rate in the TD direction based on the following formula (1).

[0013]

number

[0014] That is, by going through the predetermined steps (a) to (e) and measuring the thermal shrinkage rate at a predetermined position using motion capture, the thermal shrinkage rate can be measured quickly and accurately in a simple manner with little variation.

[0015] In carrying out the method for measuring the heat shrinkage of a polyester shrink film of the present invention, it is preferable to set multiple intervals between the two measurement positions in step (a), calculate multiple heat shrinkages in the TD direction in steps (d) and (e), and use the average value as the heat shrinkage in the TD direction. In this way, by calculating the thermal shrinkage in a plurality of TD directions, the thermal shrinkage rate in the TD direction can be measured more quickly and accurately.

[0016] When carrying out the method for measuring the thermal shrinkage rate of a polyester-based shrink film of the present invention, it is preferable to use image-based motion capture and calculate the thermal shrinkage rate in the TD direction based on the positions of specified markers before and after thermal shrinkage. In this way, by selecting and using an image-based motion capture from among the various types of motion capture, the positions of the specified markers can be calculated efficiently, and the thermal shrinkage rate can be measured quickly and accurately.

[0017] When carrying out the method for measuring the heat shrinkage rate of a polyester shrink film of the present invention, it is preferable to provide a camera in step (b) and also observe the heat shrinkage state of the polyester shrink film as the object to be measured. In this way, by also recording the camera image, the state of thermal shrinkage in the TD direction can be confirmed, and further, the thermal shrinkage rate in the TD direction can be measured more quickly and accurately.

[0018] When carrying out the method for measuring the heat shrinkage rate of a polyester shrink film of the present invention, it is preferable that the heat shrinkage temperature in step (c) is set to a value within the range of 50 to 98°C and the heat shrinkage time is set to a value within the range of 1 to 60 seconds. By setting such heat shrinkage conditions, it is possible to compare the heat shrinkage properties with those of a polyester shrink film when actually used.

[0019] When carrying out the method for measuring the heat shrinkage rate of a polyester shrink film of the present invention, it is preferable that the heat shrinkage location in step (c) is at least one of a thermostatic bath, a steam bath, a hot water bath, a fluorine-containing liquid bath, and an infrared irradiation device. By using such various heat shrinkage locations, the heat shrinkage rate can be measured more quickly, more accurately, and more simply according to the application of the polyester shrink film.

[0020] When carrying out the method for measuring the thermal shrinkage of a polyester-based shrink film of the present invention, in step (d), it is preferable to measure the thermal shrinkage in a direction perpendicular to the main shrinkage direction of the polyester-based shrink film being measured as the thermal shrinkage in the MD direction using motion capture, simultaneously with the measurement of the thermal shrinkage in the TD direction. In this way, by simultaneously measuring the thermal shrinkage rate in the MD direction using motion capture, it is possible to compare the thermal shrinkage properties of the polyester-based shrink film with those of the actual use, depending on the application of the polyester-based shrink film.

[0021] In carrying out the method for measuring the heat shrinkage rate of a polyester-based shrink film of the present invention, it is preferable to include, after step (e), a step (f) of previously preparing a calibration curve showing the relationship between the heat shrinkage temperature and heat shrinkage time in the main shrinkage direction of the polyester-based shrink film to be measured, and the heat shrinkage rate in the TD direction, and comparing and verifying the calibration curve with the heat shrinkage rate obtained based on formula (1). In this way, by performing a comparison and verification with a previously prepared calibration curve, the heat shrinkage rate can be measured more quickly, more accurately, and with better reproducibility. [Brief description of the drawings]

[0022] 1(a) to (c) are diagrams illustrating the configuration of a polyester shrink film. 2(a) to (c) are diagrams illustrating a method for measuring the thermal shrinkage rate of a polyester shrink film using a motion capture device or the like. 3(a) and 3(b) are diagrams for explaining the positional movement of a predetermined marker due to the thermal shrinkage of a polyester shrink film. 4(a) and 4(b) are diagrams provided for explaining a method for measuring the thermal shrinkage rate of a polyester shrink film using motion capture or the like. 5(a) to (c) are diagrams provided for explaining a configuration example of a fixing jig used in measuring the thermal shrinkage rate using motion capture. 6(a) and 6(b) are diagrams provided for explaining the heat shrinkage speed and the heat shrinkage rate speed, etc. FIG. 7 is a diagram provided for illustrating the relationship of the change in distance (mm) in a given section versus time (seconds) for the polyester-based shrink films of Examples 1 and 2 and Comparative Examples 2 and 3. As shown in FIG. Figures 8(a) and (b) are diagrams provided to explain the relationship of heat shrinkage speed (mm / sec) versus time (sec) for the polyester-based shrink films of Examples 1 and 2, and Figure 8(c) is a diagram provided to explain the relationship of heat shrinkage rate (% / sec) versus time. Figures 9(a) and (b) are diagrams provided to explain the relationship of heat shrinkage speed (mm / sec) versus time (sec) for the polyester-based shrink films of Comparative Examples 2 and 3, and Figure 9(c) is a diagram provided to explain the relationship of heat shrinkage rate (% / sec) versus time. FIG. 10(a) is a diagram provided to explain the relationship of the intermediate heat shrinkage speed (mm / sec) versus time (sec) for the polyester-based shrink film of Example 1, and FIG. 10(b) is a diagram provided to explain the relationship of the intermediate heat shrinkage rate speed (% / sec) versus time. FIG. 11(a) is a diagram provided to explain the relationship of the intermediate heat shrinkage speed (mm / sec) versus time (sec) for the polyester-based shrink film of Example 2, and FIG. 11(b) is a diagram provided to explain the relationship of the intermediate heat shrinkage rate speed (% / sec) versus time. FIG. 12(a) is a diagram provided to explain the relationship of intermediate heat shrinkage speed (mm / sec) versus time (sec) for the polyester-based shrink film of Comparative Example 2, and FIG. 12(b) is a diagram provided to explain the relationship of intermediate heat shrinkage rate speed (% / sec) versus time. FIG. 13(a) is a diagram provided to explain the relationship of intermediate heat shrinkage speed (mm / sec) to time (sec) for the polyester-based shrink film of Comparative Example 3, and FIG. 13(b) is a diagram provided to explain the relationship of intermediate heat shrinkage rate speed (% / sec) to time. Figure 14(a) is a diagram to explain multiple measurement samples (W, C, E) taken along the TD direction from a roll of polyester shrink film, and Figure 14(b) is a diagram to explain the state in which a motion capture device is attached to one of the measurement samples (W, C, E). FIG. 15 is a diagram provided to explain the relationship between the immersion time in 95° C. hot water for 1 to 20 seconds and the thermal shrinkage rate (%) in the TD direction measured using motion capture in Example 1 (line A) and Comparative Example 1 (line B). FIG. 16 is a diagram provided to explain the relationship between the thickness (μm) of a polyester shrink film when immersed in 95° C. warm water for 20 seconds and the thermal shrinkage rate (%) in the TD direction measured using motion capture. Figure 17(a) corresponds to Example 1 and is a diagram (photograph) showing the external appearance of a cylindrical label when no wrinkles have occurred, and Figures 17(b) to (d) are enlarged views of areas P, Q, and R of the appearance shown in Figure 17(a), respectively. Figure 18(a) corresponds to Comparative Example 1 and is a diagram (photograph) showing the external appearance of a cylindrical label when wrinkles occur, and Figures 18(b) to (d) are enlarged views of areas S, T, and U of the appearance shown in Figure 18(a), respectively. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] [First embodiment] The first embodiment is a method for measuring the thermal shrinkage rate of a polyester-based shrink film using motion capture, as illustrated in FIG. 1, and is characterized by having the following steps (a) to (e). Step (a): A step of setting two measurement positions in the main shrinkage direction of a polyester shrink film as a measurement object, and measuring the distance between the two measurement positions as L1. Step (b): Providing a predetermined marker at each of the two measurement positions. Step (c): A step of heating the polyester shrink film at a temperature and for a period of time that constitutes a predetermined heat shrinkage condition, thereby causing the film to heat shrink. Step (d): A step of measuring the distance between the two measurement positions after thermal shrinkage as L'1 using motion capture. Step (e): A step of calculating the thermal shrinkage rate in the main shrinkage direction of the polyester shrink film based on the following formula (1).

[0024]

number

[0025] Hereinafter, various parameters and the like will be specifically described for each configuration of the polyester shrink film of the first embodiment, with reference to the drawings as appropriate.

[0026] 1. Polyester shrink film (1) Polyester resin Basically, the type of polyester resin is not important, but it is usually preferable that the polyester resin is a polyester resin composed of a diol and a dicarboxylic acid, a polyester resin composed of a diol and a hydroxycarboxylic acid, a polyester resin composed of a diol, a dicarboxylic acid, and a hydroxycarboxylic acid, or a mixture of these polyester resins.

[0027] (2) Composition It is preferable to incorporate various additives into the polyester shrink film of the first embodiment, or to attach them to one or both sides of the film. More specifically, at least one of hydrolysis inhibitors, antistatic agents, ultraviolet absorbers, infrared absorbers, colorants, organic fillers, inorganic fillers, organic fibers, inorganic fibers, etc. is preferably blended in an amount of 0.01 to 10% by weight, more preferably 0.1 to 1% by weight, based on the total weight of the polyester-based shrink film.

[0028] As shown in FIG. 1(b), it is also preferable to laminate other resin layers 10a, 10b containing at least one of these various additives on one or both sides of the polyester shrink film 10. In this case, when the thickness of the polyester shrink film is taken as 100%, the single layer thickness or total thickness of the other resin layers to be additionally laminated is preferably set to a value within the range of 0.1 to 10%.

[0029] The resin as the main component constituting the other resin layer may be a polyester resin similar to that of the polyester-based shrink film, or it is preferable that it is at least one of a different acrylic resin, an olefin resin, a urethane resin, a rubber resin, etc.

[0030] Furthermore, it is also preferable to make the polyester-based shrink film have a multi-layer structure to further prevent hydrolysis and provide mechanical protection, or to provide a shrinkage rate adjustment layer 10c on the surface of the polyester-based shrink film 10 so that the shrinkage rate of the polyester-based shrink film is uniform within the plane, as shown in Figure 1(c). The shrinkage adjusting layer can be laminated by using an adhesive, a coating method, a heat treatment, or the like depending on the shrinkage characteristics of the polyester shrink film.

[0031] More specifically, the thickness of the shrinkage rate adjustment layer is in the range of 0.1 to 3 μm, and if the shrinkage rate of the polyester-based shrink film at a specified temperature is excessively large, it is preferable to laminate a shrinkage rate adjustment layer of a type that suppresses this. When the shrinkage rate of a polyester shrink film at a given temperature is excessively small, it is preferable to laminate a shrinkage rate adjusting layer that expands the shrinkage rate. Therefore, the present invention aims to obtain a desired shrinkage rate for a polyester-based shrink film by using a shrinkage rate adjusting layer, without producing various types of shrink films with different shrinkage rates.

[0032] 2. Process (a) Step (a) is a step of preparing a polyester shrink film as a measurement object, setting two measurement positions in the main shrinkage direction of the film, and measuring the distance between the two measurement positions, which is defined as L1. That is, it is preferable to first prepare, as raw materials, base materials and additives such as crystalline polyester resin, non-crystalline polyester resin, rubber-based resin, antistatic agent, hydrolysis inhibitor, etc. Next, it is preferable to put the prepared crystalline polyester resin, non-crystalline polyester resin, etc. into a stirring vessel while weighing them, and mix and stir them using a stirring device until they become uniform.

[0033] Next, the homogeneously mixed raw materials are preferably dried to an absolutely dry state. Typically, it is preferable to carry out extrusion molding to prepare a raw sheet having a predetermined thickness. More specifically, for example, extrusion molding can be performed using an extruder (manufactured by Tanabe Plastic Machinery Co., Ltd.) with an L / D of 24 and an extrusion screw diameter of 50 mm under conditions of an extrusion temperature of 260°C, to obtain a raw sheet of a predetermined thickness (usually 10 to 100 μm).

[0034] Next, the obtained raw sheet is preferably heated and pressed using a shrink film manufacturing device while being moved over or between rolls to produce a polyester-based shrink film. In other words, it is preferable to crystallize the polyester molecules that make up the polyester-based shrink film into a predetermined shape by stretching the film in a predetermined direction while heating and pressing it at a predetermined stretching temperature and stretching ratio, while basically expanding the film width. Then, by solidifying in this state, a heat-shrinkable polyester shrink film for use as decoration, labels, etc. can be produced. At this stage, it is preferable to measure the haze, glass transition point, and various thermal properties of the polyester shrink film in advance.

[0035] Next, as shown in FIG. 3(a), it is preferable to carry out a step of setting two measurement positions (P1 and P2) in the TD direction, which is the main shrinkage direction of the polyester shrink film 10 before it is heat-shrunk. The distance between the two measurement positions (P1 and P2) in the TD direction before thermal shrinkage is defined as L1.

[0036] Furthermore, the value of the distance L1 (mm) between the two measurement positions is preferably selected appropriately depending on the size of the polyester shrink film and the type of motion capture, but is preferably set to a value within the range of, for example, 3 to 300 mm. The reason for this is that with such a distance, the difference in distance between before and after the film shrinks can be clearly recognized, and the thermal shrinkage rate in the TD direction can be measured more quickly and accurately. Therefore, it is more preferable that the interval L1 (mm) between the measurement positions is set to a value within the range of 5 to 100 mm, and even more preferable that it is set to a value within the range of 8 to 30 mm.

[0037] In addition, when the planar shape of the polyester shrink film is a strip (rectangle) or square, the two measurement positions (P1 and P2) are preferably located at least 5 mm from the ends so that both ends are free. At this time, it is preferable to confirm that the thickness of the polyester shrink film is within a predetermined range.

[0038] The measurement position is a portion indicating positional information of coordinates provided on the polyester shrink film in order to measure the behavior of the polyester shrink film during thermal shrinkage. That is, as shown in Figures 4(a) to (b), it is preferable that a predetermined marker 15 such as a dot, line, cross, circle, arrow, L letter, T letter, check mark, etc. is marked as a predetermined section M between two measurement positions. The reason for this is that, with this configuration, the shrinkage of the polyester shrink film can be easily observed from the surroundings.

[0039] In addition, as shown in FIG. 3(a), it is preferable to carry out a step of setting two measurement positions (P3 and P4) other than the above-mentioned two measurement positions (P1 and P2) in the MD direction, which is a direction perpendicular to the main shrinkage direction. It is preferable that the distance between the two measurement positions (P3 and P4) in the MD direction before thermal shrinkage is L2. Here, the two measurement positions in the MD direction (P3 and P4) are preferably located at positions typically 5 mm or more from the ends, similar to the measurement positions in the TD direction, when the planar shape of the polyester shrink film is a strip (rectangle) or a square.

[0040] 3. Process (b) Step (b) is a step of providing predetermined markers at two measurement positions (P1 and P2) on the polyester shrink film, as shown in FIG. That is, when image-based motion capture is used, it is preferable to insert, for example, an oil-based marker, a metal wire, a groove, or the like as a predetermined marker, and photograph the position of the predetermined marker with an optical camera. Next, it is preferable to obtain the distance between the two measurement positions based on the relationship with the actual measurement by reading the number of pixels from the data of the captured video. Therefore, by selecting and using an image-based motion capture from among various types of motion capture, the positions of the predetermined markers can be calculated efficiently, and the thermal shrinkage rate can be measured quickly and accurately. On the other hand, when inertial motion capture is used, it is preferable to attach an inertial marker as the predetermined marker. In other words, the IMU (the main part of the motion capture), which includes an accelerometer and a gyroscope, can acquire acceleration information from the inertial marker more efficiently and accurately, thereby enabling the thermal shrinkage rate in the TD direction to be measured more quickly and accurately.

[0041] In addition, when cutting out multiple measurement samples from three locations (W, C, E) along the TD direction as shown in Figure 4, it is necessary to attach inertial markers to each of the two measurement positions of each measurement sample. In the case where measurement samples are cut out from three locations (W, C, E) along the TD direction as shown in FIG. 4 to prepare multiple samples, it is preferable to provide predetermined markers at two measurement positions on each measurement sample (W, C, E) and perform measurements.

[0042] Here, the inertial sensor 14' shown in Figure 4 is a combination of a long-axis sensor and several short-axis sensors that intersect it at 90° at equal intervals, and it is preferable that at least two measurement points are provided at any position with a predetermined interval. However, the inertial sensor 14' is not limited to these combinations, and it is also preferable that the planar shape be at least one of a circle, a triangle, a square, a polygon, and an irregular shape. Furthermore, it is preferable that the measuring device be made of a metal marker or a printed material such as paint containing a metallic material, so that sensing can be performed more quickly and accurately for at least two measuring points.

[0043] 4. Process (c) Step (c) is a step of heat shrinking a polyester shrink film as a measurement object by heating it at a predetermined temperature for a predetermined time using a heat shrinking device, thereby causing the film to heat shrink. The heat shrinking device is preferably at least one of a thermostatic bath (oven), a steam bath, a hot water bath, a hot air heater, a liquid bath of a fluorine-containing compound, a steam bath of a fluorine-containing compound, and an infrared ray irradiation device. The reason for this is that when motion capture is used, various types of heat shrinkage devices can be used depending on the application of the polyester-based shrink film, and thus the heat shrinkage rate can be measured more easily and accurately.

[0044] As an example, the heat shrinking device is preferably a hot water bath. The reason for this is that by using such a heat shrinking device, it is easy to keep the temperature of the hot water constant, and the heat shrinking temperature can be controlled more precisely. Furthermore, by using a hot water bath, the polyester shrink film can be floated and heated uniformly in a flat plane, making it easier to capture the behavior of the polyester shrink film during thermal shrinkage from above using an optical camera, etc.

[0045] As another example, it is preferable to use a hot air heater as the heat shrinking device. In other words, it is preferable to use a device as the hot air heater in which air supplied by a compressed air pump or a fan or the like is blown onto the object via a heat source such as an electric heating wire or an oil heater. Specifically, for example, the heat shrinkage device is preferably configured to blow hot air vertically above a polyester-based shrink film placed flat on a belt conveyor or a mounting table, thereby causing the polyester-based shrink film to heat shrink. The reason for this is that the use of such a heat shrinkage device allows for greater freedom in the location of the device, and it can be placed above the polyester shrink film manufacturing equipment, and the heat shrinkage rate can be measured more easily in-line by blowing hot air onto the cut-off ends, etc. Therefore, when using a hot air heater in this manner, from the standpoint of effectively transferring the heat of the hot air to the polyester-based shrink film, it is preferable for the polyester-based shrink film to be configured so that it receives the hot air within a tunnel-shaped housing made of stainless steel, aluminum, glass, etc.

[0046] Specifically, as shown in Figures 2(a) to (c), for example, a hot water bath 20 containing hot water 22 maintained at a predetermined temperature by a heater 22a is prepared, and the polyester shrink film is immersed in the hot water under conditions of a heat shrinkage temperature of 70 to 98°C and a shrinkage time of 1 to 60 seconds, thereby heat shrinking the polyester shrink film in the TD direction. In this case, as shown in Figure 2 (b), it is preferable to prepare a mesh-shaped fixing jig 12 made, for example, of stainless steel wire so that the polyester-based shrink film is uniformly immersed and heated, and to partially house the polyester-based shrink film 10 inside it. Furthermore, it is preferable that openings 12' of a predetermined size are provided in the fixing jig 12 at locations corresponding to the measurement points P1 and P2 so that the shrinkage rate can be measured using motion capture or the like while preventing the polyester shrink film 10 from stretching in the thickness direction.

[0047] In addition, it is preferable that at least two linear objects 26 are attached to both ends of the polyester-based shrink film 10 via a fixing jig 12 so that the polyester-based shrink film is further immersed and heated uniformly for a predetermined period of time. In other words, it is preferable that the wires or the like serving as these linear objects 26 are further connected to a lifter 24, and that the lifter 24 is configured to be able to move up and down at a constant speed while winding up and unwinding the linear object 26 and maintaining the horizontal orientation of the polyester-based shrink film 10.

[0048] Furthermore, in order to prevent temperature unevenness, the process of thermally shrinking the polyester-based shrink film is preferably carried out by immersing the polyester-based shrink film 10 in warm water in a warm water bath 20 to thermally shrink it, as shown in FIG. 2(b). On the other hand, from the viewpoint of quicker and simpler measurement, it is also preferable to float the polyester-based shrink film 10 on the surface of hot water 22 maintained at a predetermined temperature in a hot water bath 20 and allow it to thermally shrink, as shown in Figures 2(a) and (c).

[0049] In addition, when thermally shrinking the polyester shrink film, it is preferable to use a frame-shaped fixing jig that maintains the position of the polyester shrink film without interfering with the shrinkage of the polyester shrink film. That is, as illustrated in Figures 5(a) to (c), the fixing jig 12 is preferably composed of a frame member and has at least a mounting portion 13a for mounting and holding the polyester-based shrink film, a guide portion 13b for controlling the shrinkage direction of the polyester-based shrink film, and a regulating portion 13c for preventing misalignment during thermal shrinkage. Furthermore, from the viewpoint of improving ease of handling, the fixing jig 12 is preferably provided with a handle portion 13d that is disposed at least at the end portion in the main contraction direction of the placement portion 13a and protrudes obliquely upward. Specifically, the fixing jig is preferably made of a metal wire such as stainless steel, iron, aluminum, copper, etc., or a frame member made of resin, etc. The reason for this is that such a configuration allows the polyester shrink film to be stably placed, reduces shaking during thermal shrinkage, and allows the thermal shrinkage speed to be measured with greater accuracy.

[0050] Furthermore, from the standpoint of ease of handling and uniform heating of the polyester-based shrink film, the placement portion is preferably a substantially flat frame-like portion, and when viewed in a plan view from vertically above, is preferably a portion having two rails parallel to at least the main shrinkage direction. Furthermore, it is preferable that the guide portion is disposed parallel to the placement portion when viewed vertically from above in a plan view, and is a portion that is curved in a wavy manner up and down in the vertical direction. In addition, the regulating portion is arranged to bridge the guide portion in a direction perpendicular to the main shrinkage direction, and is a portion that is movable up and down along the frame of the guide portion, and is a portion that clamps the polyester-based shrink film placed on the placing portion between the placing portion and the regulating portion. The reason for this is that by configuring it in this manner, it is possible to prevent the polyester-based shrink film from shifting position during thermal shrinkage, and to stabilize the center position of the shrinkage, making it possible to accurately measure the thermal shrinkage speed by motion capture. Furthermore, by curving the guide portion into a wavy shape, for example, when a warm water bath is used as a heat shrinking device during heat shrinking, the sample can be landed on the water without creating waves, and by adjusting the height of the guide portion to match the water level, it can be placed at the bottom of the bath and measured.

[0051] 5.Process (d) Step (d) is a step of measuring the distance between two measurement positions (P1' and P2') in the TD direction of the heat-shrunk polyester shrink film 10' as a second distance, as shown in FIG. 3(b). That is, as shown in Figures 3(b) and 4, it is preferable to prepare a specified motion capture device 14 and use the motion capture device 14 to measure the distance between two measurement positions in the TD direction of a polyester-based shrink film that has been thermally shrunk under specified conditions, as L'1 (sometimes referred to as the second distance). On the other hand, it is also preferable to measure the distance between two measurement positions continuously (for example, at time intervals of 0.01 to 1 second) using a motion capture device or the like before or during the heat shrinkage of the polyester shrink film.

[0052] Moreover, as shown in FIG. 3(b), it is preferable to carry out a measurement step using motion capture with the distance between two measurement positions (P3' and P4') in the MD direction set as a second' distance. The distance between the two measurement positions (P3' and P4') in the MD direction after thermal shrinkage is defined as L'2. That is, it is preferable to measure the second' distance in the MD direction in the same manner as measuring the second distance in the TD direction.

[0053] The interval between measurement positions on the polyester shrink film is preferably calculated based on position information of the measurement positions obtained by motion capture. The reason for this is that by using such motion capture, the distance between measurement positions on the film can be obtained as digital data quickly and accurately. Here, motion capture is a technology for converting the movement of a measurement target into digital data, and is a technology that mainly tracks the position of a predetermined marker on the measurement target and records it as coordinate data.

[0054] Specifically, the type of motion capture is not particularly limited, but may be image-based motion capture, inertial motion capture, optical motion capture, or a combination of these, and any type of motion capture may be used. However, in the case of polyester shrink film, since it is heated by immersion in warm water, etc., there are many spatial limitations, and since it is easy to make the device smaller and simpler, it is preferable to use image-based or inertial-based motion capture.

[0055] Here, when a single motion capture is used, the thermal shrinkage rate can be measured and calculated from two-dimensional measurement points, but when multiple motion captures are used, there is an advantage that the positional relationship of three-dimensional measurement points can be measured, and then the thermal shrinkage rate can be measured and calculated. For example, when a flat hot plate is used as the heat shrinkage device, the heat shrinkage rate can be easily and quickly measured three-dimensionally even when the hot plate is tilted not only horizontally but also along the direction of gravity, or even when the hot plate is placed vertically so as to be parallel to the direction of gravity. Therefore, when using a single or multiple motion capture devices, various types of heat shrinkage devices can be used, making it possible to measure the heat shrinkage rate more quickly, accurately, and simply depending on the application of the polyester-based shrink film.

[0056] More specifically, as shown in FIG. 2(a), it is preferable to use an optical camera as an image-based motion capture device 14 to capture video of a polyester shrink film 10 as the object to be measured during thermal shrinkage, and to measure the thermal shrinkage rate by performing image analysis of the acquired data. That is, it is preferable that a plurality of marks (for example, 2 to 30 marks) are provided in advance at intervals L1 on a polyester shrink film using a predetermined marker such as an oil-based marker. Next, the polyester shrink film is placed on a flat surface, and video images are preferably taken from vertically above with an optical camera before and after thermal shrinkage. Furthermore, it is preferable that the distance between each memory before thermal shrinkage is calculated from the pixel count and actual measurement data from the captured video data, and the average value is used as the thermal shrinkage rate. Specifically, for example, in an embodiment where marks are lined up on the left and right, it is preferable to draw a horizontal imaginary line so as to intersect with each mark, and to determine the point where the mark and the imaginary line intersect as the measurement position. The reason for this is that by continuously recording the thermal shrinkage state as video data, the thermal shrinkage rate in the TD direction can be measured more quickly, accurately, and efficiently. By recording in this manner, even in cases where there are many space limitations, the device can be made smaller and simpler, and the thermal shrinkage rate can be measured more efficiently. The type of the specified marker may be any type that is easily visible to an optical camera, and is preferably, for example, an oil-based marker, a groove, or the like.

[0057] In addition, it is preferable that the motion capture be configured as an inertial position measuring device that can obtain acceleration, angular velocity, and orientation information from an inertial sensor attached to a polyester-based shrink film using an IMU or other device, and accurately identify the position of a marker (center of gravity, etc.). In other words, it is preferable to use an inertial motion capture device equipped with a 9-axis inertial sensor that combines an accelerometer and an angular velocity meter (gyro sensor), and further, a combination of these with a geomagnetometer.

[0058] On the other hand, it is also preferable to use optical motion capture as the motion capture. In other words, it is preferable that the motion capture device be a type of optical position measuring device that irradiates radiation such as infrared rays toward an optical marker (such as a retroreflective marker) and detects the reflected light. This motion capture is a measuring device that can perform a specified image processing based on the obtained reflected light and identify the position of the marker (center of gravity, etc.) in two dimensions, and furthermore, by using multiple motion captures in combination, it is possible to identify the position in three dimensions.

[0059] Furthermore, as shown in Figures 2(b) to (c), it is preferable to use predetermined optical cameras 14a, 14b in combination with the inertial motion capture device 14 to photograph the thermal shrinkage state of the polyester shrink film 10 and use the photographed image data as a reference for measuring the thermal shrinkage rate. The reason for this is that by continuously recording the thermal shrinkage state together with the camera images in this manner, the state of thermal shrinkage in the TD direction can be confirmed as image data, and thus the thermal shrinkage rate in the TD direction can be measured more efficiently and accurately. More specifically, it is preferable to prepare one or more optical cameras and capture image data of the thermal shrinkage state of the polyester-based shrink film from the front, side, top, back, or oblique direction of the polyester-based shrink film as the object to be measured.

[0060] 6. Process (e) Step (e) is a step of calculating the heat shrinkage rate in the main shrinkage direction of the polyester shrink film as the heat shrinkage rate in the TD direction based on formula (1). That is, it is preferable to calculate the thermal shrinkage rate in the TD direction from the obtained L1 and L2 based on the formula (1).

[0061] In addition, when calculating the thermal shrinkage rate in the TD direction, it is preferable to set the interval between the two measurement positions at multiple points, calculate the thermal shrinkage in the TD direction at multiple points, and use the average value as the thermal shrinkage rate in the TD direction. That is, it is preferable to select multiple different locations (for example, n=3 to 30 locations) of the same film, measure the heat shrinkage (temperature: 70 to 98° C., time: 1 to 60 seconds), and use the average value as the heat shrinkage in the TD direction. The reason for this is that by calculating the thermal shrinkage in the TD direction at a plurality of locations, the thermal shrinkage rate in the TD direction can be measured more quickly and accurately. Therefore, it is more preferable to select at least 4 to 20 measurement positions in the TD direction of the polyester shrink film, and it is even more preferable to select 5 to 10 measurement positions.

[0062] Here, referring to FIG. 5, the relationship between the immersion time in 95° C. hot water and the thermal shrinkage rate (%) in the TD direction measured using motion capture in Example 2 and Comparative Example 1 will be described. That is, the horizontal axis of FIG. 5 indicates the immersion time (seconds), and the vertical axis indicates the thermal shrinkage rate (%) in the TD direction measured using motion capture. In the case of the characteristic curve (line A) of Example 2, when the immersion time is about 1 second, almost the same heat shrinkage rate (%) is obtained, even when compared with the value after 20 seconds.

[0063] In contrast, in the case of the characteristic curve (line B) of Comparative Example 1, when comparing the heat shrinkage rate (%) when the immersion time is 1 second with the heat shrinkage rate when the immersion time is 20 seconds, there is a tendency that the longer the immersion time, the greater the heat shrinkage rate (%). Therefore, it is preferable to determine the immersion time taking into consideration the PET resin used, the thickness and thermal properties of the polyester shrink film obtained from it, and further the manufacturing conditions.

[0064] Furthermore, referring to FIG. 6, the relationship between the thickness (μm) of a polyester shrink film when immersed in 95° C. hot water for 20 seconds and the thermal shrinkage rate (%) in the TD direction measured using motion capture will be described. That is, the horizontal axis of FIG. 6 shows the thickness (μm) of the polyester shrink film, and the vertical axis shows the thermal shrinkage rate (%) in the TD direction measured using motion capture.

[0065] Therefore, in the case of this characteristic curve (line C), it can be understood that the thicker the polyester-based shrink film (μm), the lower the thermal shrinkage rate (%), and there is a certain correlation (linear relationship). Therefore, it is preferable to adjust the heat shrinkage rate (%) taking into consideration the thickness and thermal properties of the polyester shrink film.

[0066] 7.Process (f) It is preferable to provide a step (f) and confirm, while comparing with a calibration curve, that the obtained predetermined heat shrinkage rate (temperature: 70 to 98°C, time: 1 to 60 seconds) is a predetermined value or more (for example, 20% or more). In other words, it is preferable to confirm that the thickness and thermal shrinkage of the polyester shrink film match each other against a pre-prepared calibration curve showing the relationship between the thickness of the polyester shrink film and the thermal shrinkage measured using motion capture. Conversely, if the thermal shrinkage rate falls below 20%, it is preferable to reduce the thickness of the polyester-based shrink film or change the raw materials or manufacturing conditions of the polyester-based shrink film to adjust the thermal shrinkage rate to be within the specified range. Therefore, it is preferable to confirm that the specified thermal shrinkage rate (temperature: 70 to 98°C, time: 1 to 60 seconds) is a value of less than 30 to 95%, more preferably a value within the range of 40 to less than 90%, and even more preferably a value of less than 50 to 85%.

[0067] More specifically, it is preferable to adjust the thermal shrinkage ratio A1 in the TD direction, when the main shrinkage direction is the TD direction and the film is shrunk at a temperature of 95°C for 1 second, to a value within the range of 30% to less than 95%. The reason for this is that by limiting the 95° C. heat shrinkage percentage A1 to less than 30 to 95%, the polyester-based shrink film can obtain good wrinkle properties during heat shrinkage, and furthermore, the maximum shrinkage stress can be easily obtained. Therefore, it is more preferable to adjust the 95° C. heat shrinkage rate A1 to a value within the range of 40 to less than 90%, and further preferably to a value within the range of 50 to less than 85%.

[0068] It is also preferable to adjust the main shrinkage direction to the TD direction, and to adjust the heat shrinkage rate A'1 in the TD direction when shrinking at a temperature of 95°C for 10 seconds to within a range of 60 to less than 95%. The reason for this is that by limiting the 95° C. heat shrinkage rate A′1 to less than 60 to 95%, the polyester-based shrink film can obtain good wrinkle properties during heat shrinkage, and therefore the maximum shrinkage stress can also be easily obtained. Therefore, it is more preferable to adjust the 95° C. heat shrinkage rate A′1 to a value within the range of 65 to less than 90%, and further more preferable to adjust it to a value within the range of 70 to less than 85%.

[0069] In addition, it is preferable that the polyester shrink film to be measured has a configuration (a2) in which the main shrinkage direction is the TD direction, and the thermal shrinkage ratio A2 in the TD direction when shrunk at a temperature of 80°C for 1 second is within the range of 10 to less than 80%. The reason for this is that by setting the 80°C heat shrinkage rate A2 within a specified range, a better heat shrinkage rate can be obtained in the polyester-based shrink film during heat shrinking, and ultimately the maximum shrinkage stress can also be more easily obtained. Therefore, in the configuration (a2), the 80° C. heat shrinkage rate A2 is more preferably set to a value within the range of 15 to less than 70%, and further preferably set to a value within the range of 20 to less than 50%.

[0070] In addition, it is preferable that the polyester shrink film to be measured has a configuration (a'2) in which the main shrinkage direction is the TD direction, and the thermal shrinkage rate A'2 in the TD direction when shrunk at a temperature of 80°C for 10 seconds is within the range of 10 to less than 85%. The reason for this is that by setting the 80° C. heat shrinkage rate A′2 within a predetermined range, a better heat shrinkage rate can be obtained, and furthermore, the maximum shrinkage stress can also be easily obtained. Therefore, in the configuration (a'2), the 80° C. heat shrinkage rate A'2 is more preferably set to a value within the range of 20 to less than 75%, and further preferably to a value within the range of 30 to 65%.

[0071] It is also preferable to carry out a step of calculating the heat shrinkage rate in the MD direction from L2, which is the distance between the two points before heat shrinkage, and L'2, which is the distance between the two points after heat shrinkage, in the same manner as the heat shrinkage rate in the TD direction, and adjusting the heat shrinkage rate in the MD direction. It is preferable to adjust the heat shrinkage rate in the MD direction of the polyester shrink film to a value within the range of −5 to 5%. The reason for this is that by simultaneously adjusting the thermal shrinkage rate in the MD direction in this manner, the thermal shrinkage characteristics of the polyester-based shrink film when actually used can be more easily controlled depending on the application, etc. of the polyester-based shrink film.

[0072] Moreover, the predetermined adjustment step preferably includes a step of adjusting the standard deviation of the heat shrinkage rate (temperature: 70 to 98° C., time: 1 to 60 seconds). More specifically, when calculating the thermal shrinkage in the TD direction, it is preferable to adjust the standard deviation (σ1) of the thermal shrinkage in the TD direction at a predetermined temperature for a predetermined time to within 15%. In other words, if the standard deviation of the thermal shrinkage rate in the TD direction exceeds 15%, it is preferable to reduce the thickness of the polyester-based shrink film or change the raw materials or manufacturing conditions of the polyester-based shrink film so that the standard deviation of the thermal shrinkage rate is within a specified range. The reason for this is that by adjusting the standard deviation of the heat shrinkage rate in this manner, the heat shrinkage rate of the polyester-based shrink film can be controlled with greater precision. Therefore, it is more preferable to adjust the standard deviation of the thermal shrinkage rate in the TD direction to a value within 10%, and even more preferable to adjust it to a value within 5%.

[0073] It has also been found that the thermal shrinkage measured using motion capture can be affected by the thickness of the polyester shrink film. In other words, it is preferable to adjust the thickness of the polyester-based shrink film to a range of 10 to 200 μm, and to adjust the difference between the maximum thickness and the average thickness (hereinafter sometimes referred to as thickness variation) to a value within 10 μm. The reason for this is that by controlling the thickness and thickness variation of such a polyester-based shrink film, it becomes easier to control the thermal shrinkage rate in the TD direction, and ultimately, it becomes possible to control the thermal shrinkage rate in the TD direction more quickly and accurately. However, if the variation in thickness is excessively small, the manufacturing yield will be extremely low, which may be economically disadvantageous. Therefore, it is more preferable to adjust the thickness variation to a value within the range of 0.01 to 5 μm, and even more preferable to adjust the thickness variation to a value within the range of 0.1 to 3 μm.

[0074] Furthermore, when measuring the thermal shrinkage rate using motion capture, the haze value of the polyester shrink film may affect the accuracy of image reading, etc. That is, when measuring the heat shrinkage rate, it is preferable to adjust the haze value of the polyester shrink film measured in accordance with JIS K 7136:2000 to a value of 7% or less. On the other hand, if the haze value of the film before heat shrinkage becomes too small, it becomes difficult to control it stably, and the production yield may decrease significantly. Therefore, it is more preferable to adjust the haze value of the film before heat shrinkage to a value within the range of 0.1 to 5%, and even more preferable to adjust to a value within the range of 0.5 to 3%.

[0075] 8. Adjustment of other thermal properties (1) Heat shrinkage speed As a step of adjusting other thermal properties, it is preferable to include a step of adjusting thermal properties such as the thermal shrinkage rate described below. Specifically, when a polyester-based shrink film is thermally shrunk in the main shrinkage direction at a predetermined temperature T for a predetermined time t1, it is preferable to utilize a predetermined correlation between distance information of a predetermined section obtained by motion capture and the measurement time, and adjust the maximum value of the thermal shrinkage speed calculated based on equation (2) to fall within a predetermined range. That is, as shown in FIG. 6(a), it is preferable that the distance of a specified section measured by motion capture before thermal shrinkage is PL0, the distance of a specified section measured by motion capture at a specified time t2 shorter than specified time t1 is PL1, and the maximum value of the thermal shrinkage speed that can be calculated based on formula (2) is 3 mm / sec or more.

[0076]

number

[0077] The reason for this is that by setting the thermal shrinkage rate to this maximum value, it is possible to precisely adjust the balance between the amount of change at which the polyester-based shrink film changes most significantly and the time, thereby effectively preventing the occurrence of wrinkles and the like when the polyester-based shrink film is used on an object. Therefore, the maximum heat shrinkage speed is more preferably 3.5 mm / sec or more, and even more preferably 4 mm / sec or more. It is preferable that the distance PL0 of the predetermined section before thermal shrinkage is the same as the distance L1 and the like.

[0078] Now, referring to FIG. 7, the relationship between time (seconds) and distance change (mm) in a predetermined section will be described. That is, for Examples 1 and 2 and Comparative Examples 2 and 3 described below, the horizontal axis represents time (seconds) and the vertical axis represents the maximum value of the distance change (mm) in six predetermined sections set up at a distance of 10 mm along the main shrinkage direction, and measurements were taken at intervals of 0.1 seconds and graphed. According to this graph, it can be seen that in Example 1 and Example 2, the value increases uniformly between 0 and 2 seconds, and then continues to increase slowly. It can also be seen that in Comparative Example 2, there is a portion between 0 and 1 second where the distance change in a predetermined section decreases. On the other hand, in Comparative Example 3, it can be seen that the change in distance in a given section increases gradually between 0 and 1 second, rises sharply between 1 and 2 seconds, and then drops slightly. Furthermore, it can be seen that in Comparative Example 3, after 1 second has elapsed since the start of thermal shrinkage, the curve is about 1 / 3 to 1 / 2 of the other relationship curves.

[0079] Furthermore, the relationship between time (seconds), heat shrinkage speed (mm / second), and heat shrinkage rate speed (% / second) will be described with reference to FIGS. 8(a)-(b) and 9(a)-(b). Specifically, for Examples 1 and 2 and Comparative Examples 1 and 2 described later, the horizontal axis represents time (seconds) and the vertical axis represents the thermal shrinkage speed of the section with the smallest maximum value (mm / second) among six predetermined sections set at 10 mm intervals along the main shrinkage direction, and the graphs were drawn at 0.1 second intervals. 8(a)-(b), it can be seen that in Examples 1 and 2, the thermal shrinkage speed increases relatively stably immediately after the start of thermal shrinkage, exceeds 3 mm / sec after about 1 second, and then decreases to 3 mm / sec or less within 1-2 seconds. On the other hand, from Figures 9(a) to (b), it can be seen that in Comparative Example 2 and Comparative Example 3, the thermal shrinkage speed does not increase significantly immediately after the start of thermal shrinkage, and does not exceed 3 mm / sec even after 1 second has elapsed from the start of thermal shrinkage. In the cases of Fig. 8(c) and Fig. 9(c), a thermal shrinkage speed of 1 mm / sec corresponds to a thermal shrinkage rate speed of 10% / sec.

[0080] (2) Heat shrink rate speed As shown in FIG. 6(a), it is preferable that the polyester shrink film has a maximum heat shrinkage rate in the main shrinkage direction calculated based on the following formula (3) of 30% / sec or more.

[0081]

number

[0082] The reason for this is that by setting this thermal shrinkage rate speed, it is possible to precisely adjust the balance between the amount of change at which the polyester-based shrink film changes most significantly and the time, thereby effectively preventing the occurrence of wrinkles and the like when the polyester-based shrink film is used on an object. Furthermore, by measuring the amount of change in the thermal shrinkage rate, it is possible to evaluate the polyester shrink film without depending on the distance of a specified section. Therefore, the maximum value of the heat shrinkage rate is more preferably 3.5% / sec or more, and even more preferably 4% / sec or more.

[0083] (3) Standard deviation of maximum heat shrinkage rate In addition, for polyester-based shrink film, when a plurality of specified sections are provided and the thermal shrinkage rate speed for each specified section from the start of thermal shrinkage to a specified time t1 is calculated every 0.1 seconds, it is preferable that the standard deviation of the maximum thermal shrinkage rate for each specified section be 3.5 mm / sec or less. The reason for this is that by using such a standard deviation, the rate of shrinkage per unit time during thermal shrinkage can be adjusted with high precision, and the behavior during thermal shrinkage becomes more stable. Therefore, the standard deviation of the maximum value of the thermal shrinkage speed is more preferably 1 mm / sec or less, and even more preferably 0.3 mm / sec or less. The standard deviation is the square root of the sum of the squares of the deviations divided by the number of data points minus 1.

[0084] (4) Heat shrinkage speed over a specified period (intermediate heat shrinkage speed) In addition, as shown in Figure 6 (b), a polyester-based shrink film has a predetermined section along the main shrinkage direction of the polyester-based shrink film in a state where it can shrink in at least one of the longitudinal direction or the width direction, and is heat-shrunk at a predetermined temperature T for a predetermined time t1.The heat shrinkage speed in the main shrinkage direction during a predetermined period (hereinafter sometimes referred to as intermediate heat shrinkage speed) is preferably 20 mm / sec or less, as calculated based on the change in distance between the distance PL0 of the predetermined section before heat shrinkage, the distance PL1 of the predetermined section at a predetermined time t2 that is shorter than the predetermined time t1, and the distance PL2 of the predetermined section at a predetermined time t3 that is shorter than the predetermined time t1 and longer than the predetermined time t2, based on the following formula (4):

[0085]

number

[0086] The reason for this is that by using such an intermediate heat shrinkage speed, a predetermined correlation can be utilized between the change in distance of a predetermined section of the polyester shrink film during heat shrinkage and position information obtained by motion capture, etc. In turn, the heat shrinkage speed of the polyester shrink film can be adjusted to a value within a predetermined range, allowing the polyester shrink film to exhibit excellent heat shrinkability stably. Therefore, the heat shrinkage speed during the measurement period is more preferably 18 mm / sec or less, and even more preferably 15 mm / sec or less. The intermediate heat shrinkage speed is defined as positive in the shrinkage direction of the polyester-based shrink film, and is defined as a negative value when the polyester-based shrink film stretches in reaction to the shrinkage, or when the film becomes three-dimensionally distorted due to rapid heat shrinkage and then returns to a flat shape.

[0087] In addition, in the case of polyester shrink films, it is preferable that the measurement period t3-t2 is set to a value of 3 seconds or less. The reason for this is that by using such a measurement period, the behavior during thermal contraction can be measured with higher accuracy. Therefore, it is more preferable to set the measurement period t3-t2 to a value of 2 seconds or less, and even more preferable to set it to a value of 1 second or less. On the other hand, in order to prevent an increase in measurement errors due to an excessive increase in time resolution, it is preferable to set the measurement period t3-t2 to a value of 0.1 seconds or more.

[0088] In addition, it is preferable that the intermediate heat shrinkage speed is always a positive value during heat shrinkage, but even if it becomes a negative value, it has been found that there is no problem for the intended use of the polyester-based shrink film so long as the value is small. Therefore, it is preferable that the minimum intermediate heat shrinkage speed of the polyester shrink film during a given period is controlled to -2.5 mm / sec or higher. In this way, by suppressing the behavior of the polyester-based shrink film such that the intermediate heat shrinkage rate becomes negative, wrinkles and the like can be more effectively prevented when the polyester-based shrink film is used. Therefore, the minimum value of the intermediate heat shrinkage speed is more preferably −1.5 mm / sec or more, and even more preferably 0 mm / sec or more.

[0089] Here, with reference to Figs. 10(a) to 13(a), the relationship between time (seconds) and intermediate heat shrinkage speed (mm / second) will be described. Specifically, for Examples 1 and 2 and Comparative Examples 2 and 3 described below, the horizontal axis represents time (seconds), and the vertical axis represents the intermediate heat shrinkage speed among six predetermined sections set at 10 mm intervals along the main shrinkage direction, and the intermediate heat shrinkage speed with the highest maximum value (mm / second) is graphed at 0.1 second intervals. According to Figs. 10(a) to 11(a), it can be seen that in Example 1 and Example 2, the intermediate thermal shrinkage speed reaches a maximum value between 0 and 1 second, and decreases to about 0 mm / sec after about 1 second has passed since the start of thermal shrinkage. On the other hand, according to FIG. 12(a), it can be seen that in Comparative Example 2, the intermediate thermal shrinkage speed reaches a maximum value between 0 and 1 second, but thereafter varies greatly with respect to 0 mm / sec between 1 and 2 seconds. Furthermore, according to FIG. 13(a), it can be seen that in Comparative Example 3, the intermediate thermal shrinkage speed was 5 mm / sec or less between 0 and 1 second, increased to over 20 mm / sec after about 1 second, and then decreased to 5 mm / sec or less between 1.1 and 1.5 seconds. In the cases of Figs. 10(b) to 13(b), a thermal shrinkage speed of 1 mm / sec corresponds to a thermal shrinkage rate speed of 10% / sec.

[0090] (5) Standard deviation for maximum intermediate heat shrinkage speed In addition, for polyester-based shrink film, when a plurality of specified sections are provided and the thermal shrinkage rate speed for each specified section from the start of thermal shrinkage to a specified time t1 is calculated every 0.1 seconds, it is preferable that the standard deviation of the maximum intermediate thermal shrinkage rate for each specified section be 4.5 mm / sec or less. The reason for this is that by using such a standard deviation, the shrinkage rate within a specified time during thermal shrinkage can be adjusted with high precision, and the behavior during thermal shrinkage becomes more stable. Therefore, the standard deviation of the maximum value of the intermediate heat shrinkage speed is more preferably 3.5 mm / sec or less, and even more preferably 3 mm / sec or less. The standard deviation is the square root of the sum of the squares of the deviations divided by the number of data points minus 1.

[0091] (6) Heat shrink rate speed during a given period (intermediate heat shrink rate speed) Furthermore, as shown in FIG. 6(b), when a polyester-based shrink film is heat-shrunk at a predetermined temperature T for a predetermined time t1, it is preferable that the intermediate heat shrinkage rate in the main shrinkage direction (hereinafter sometimes referred to as the intermediate heat shrinkage rate rate) calculated based on the change in distance between the distance PL0 of a predetermined section before heat shrinkage, the distance PL1 of a predetermined section at a predetermined time t2 that is shorter than the predetermined time t1, and the distance PL2 of a predetermined section at a predetermined time t3 that is shorter than the predetermined time t1 and longer than the predetermined time t2, based on the following formula (5), is 200% / sec or less.

[0092]

number

[0093] The reason for this is that by using such an intermediate heat shrinkage rate speed, the heat shrinkage rate of the polyester-based shrink film can be adjusted with greater precision regardless of the size of the polyester-based shrink film. Therefore, the intermediate heat shrinkage rate is more preferably 180% / sec or less, and even more preferably 150% / sec or less.

[0094] On the other hand, from the viewpoint of preventing defects caused by excessively small shrinkage in a short period of time, the intermediate heat shrinkage rate is preferably 60% / sec or more, more preferably 80% / sec or more, and even more preferably 90% / sec or more. It is preferable that the intermediate heat shrinkage rate is always a positive value, like the intermediate heat shrinkage rate, but even if it is a negative value, it has been found that there is no problem for the intended use of the polyester shrink film as long as the value is small.

[0095] Therefore, it is preferable that the minimum intermediate heat shrinkage rate of a polyester shrink film is controlled to -2.5% / sec or more. In this way, by suppressing the behavior of the polyester-based shrink film such that the intermediate heat shrinkage rate becomes negative, wrinkles and the like can be more effectively prevented when the polyester-based shrink film is used. Therefore, it is more preferable to set the minimum value of the intermediate heat shrinkage speed to -1.5% / sec, and further more preferable to set it to 0% / sec or higher.

[0096] In addition, when calculating the thermal shrinkage rate speed, it is preferable that the predetermined times t2 and t3 are set to 5 seconds or less. The reason for this is that by setting such a predetermined time, the behavior of the polyester shrink film during thermal shrinkage can be measured in more detail. Therefore, it is more preferable to set the predetermined times t2 and t3 within 4 seconds, and even more preferable to set them within 3 seconds.

[0097] It is also preferable that the time during which the intermediate heat shrinkage speed reaches its maximum is 1 second or less. The reason for this is that, by configuring it in this way, the timing at which the polyester-based shrink film significantly shrinks can be controlled, and the heat shrinkage characteristics can be adjusted with greater precision. Therefore, it is more preferable that the time during which the intermediate heat shrinkage speed reaches its maximum be 0.8 seconds or less, and even more preferable that it be 0.6 seconds or less.

[0098] (7) Difference in heat shrink rate per second In addition, when a polyester-based shrink film has a predetermined section along the main shrinkage direction of the polyester-based shrink film and is heat-shrunk along the main shrinkage direction at a predetermined temperature T for a predetermined time t1, the distance of the predetermined section before heat shrinkage is PL0, the distance of the predetermined section at a predetermined time t2 shorter than the predetermined time t1 is PL1, and the distance of the predetermined section at a predetermined time t3 shorter than the predetermined time t1 and longer than the predetermined time t2 is PL2, the measurement period t3-t2 is 1 second, and the difference in the heat shrinkage rate per second calculated based on the following formula (6) is usually preferably 100% / second or less under the specified conditions (predetermined temperature T: 70 to 98°C, predetermined time t1: more than 5 seconds).

[0099]

number

[0100] The reason for this is that such a difference in the heat shrinkage rate allows the polyester-based shrink film to shrink more stably. Therefore, the difference in the thermal shrinkage rate is more preferably 80% / sec or less, and even more preferably 50% / sec or less.

[0101] 9. Other inspection processes That is, it is preferable to provide a predetermined inspection process in which the following characteristics are measured continuously or intermittently for the produced polyester shrink film. That is, by measuring the following characteristics through a prescribed inspection process and confirming that they fall within prescribed ranges, a polyester-based shrink film with more uniform shrinkage characteristics can be produced. 1) Visual inspection of the appearance of polyester shrink film 2) Thickness variation measurement 3) Tensile modulus measurement 4) Tear strength measurement 5) Viscoelasticity measurement using SS curve 6) Thermal characteristics (TD direction, MD direction) 7) Heat shrinkage stress 8) Stretching ratio

[0102] [Second embodiment] The second embodiment relates to a method of using a polyester shrink film whose thermal shrinkage rate has been measured by motion capture. Therefore, any known method for using shrink films can be suitably applied. For example, when implementing the method for using a polyester shrink film, first, the polyester shrink film is cut to an appropriate length and width, and formed into a long cylindrical object. The long cylindrical object is then fed to an automatic label attachment device (shrink labeler) and further cut to the required length. Next, the container is fitted onto a PET bottle or the like filled with the contents.

[0103] Next, the polyester shrink film fitted around the PET bottle or the like is subjected to a heat treatment by passing through a hot air tunnel or steam tunnel at a predetermined temperature. These tunnels provide radiant heat such as infrared rays, or heated steam at about 90°C is sprayed onto the polyester shrink film from the surrounding area, uniformly heating the film and causing it to shrink.

[0104] Therefore, when the thermal shrinkage rate in the TD direction is 20% or more, it is possible to quickly obtain a labeled container by adhering it to the outer surface of a PET bottle or the like, as shown in Figs. 7(a) to (d). On the other hand, when the thermal shrinkage rate in the TD direction falls below 20%, as shown in Figures 8(a) to (d), there are areas from the top to the bottom of the bottle body where the label cannot conform to the shape of the bottle periphery, and wrinkles are also clearly observed. EXAMPLES

[0105] The present invention will be described in detail below based on examples. However, the scope of the present invention will not be narrowed by the description of the examples without a particular reason. The polyester resins used in Example 1 and the like are as follows:

[0106] (PETG1) Dicarboxylic acid: 100 mol% terephthalic acid, diol: 69 mol% ethylene glycol, 20 mol% 1,4-cyclohexanedimethanol, 11 mol% diethylene glycol Amorphous polyester (glass transition temperature: 69°C)

[0107] (PETG2) Dicarboxylic acid: 100 mol% terephthalic acid, diol: 63 mol% ethylene glycol, 24 mol% 1,4-cyclohexanedimethanol, 13 mol% diethylene glycol Amorphous polyester (glass transition temperature: 69°C)

[0108] (PETG3) Dicarboxylic acid: 100 mol% terephthalic acid, diol: non-crystalline polyester consisting of 68 mol% ethylene glycol, 30 mol% neopentyl glycol, and 2 mol% diethylene glycol (glass transition point: 75°C)

[0109] (PETG4) Dicarboxylic acid: 100 mol% terephthalic acid, diol: 70 mol% ethylene glycol, 28 mol% 1,4-cyclohexanedimethanol, 2 mol% diethylene glycol Amorphous polyester (glass transition temperature: 69°C)

[0110] [Example 1] 1. Preparation of polyester shrink film In a stirring vessel, 100 parts by weight of a non-crystalline polyester resin (PETG1) was used. Next, this raw material was dried and then extrusion molded at an extrusion temperature of 260° C. using an extruder (manufactured by Tanabe Plastic Machinery Co., Ltd.) with an L / D of 24 and an extrusion screw diameter of 50 mm to obtain a raw sheet having a thickness of 200 μm.

[0111] Next, using a shrink film manufacturing device, a 40 μm thick polyester shrink film was produced from the original sheet at a preheating temperature of 75°C, a stretching temperature of 75°C, a stretching ratio (MD direction: 105%, TD direction: 500%), and a heat setting temperature of 60°C.

[0112] 2. Evaluation of polyester shrink film (1) Evaluation 1: Thickness variation The thickness of the obtained polyester shrink film (a desired value of 50 μm was used as the reference value) was measured using a micrometer (n=6), and evaluated according to the following criteria. ⊚: The thickness variation is within 3 μm. ◯: Thickness variation is within 5 μm. △: The thickness variation is within 10 μm. ×: The thickness variation exceeds 10 μm.

[0113] (2) Evaluation 2: Thermal shrinkage in the TD direction (A1) The obtained polyester shrink film was immersed in hot water at 95° C. for 1 second in a hot water bath to cause thermal shrinkage. Next, as shown in FIG. 2(a), while capturing image data with an optical camera, the thermal shrinkage rate (A1) in the TD direction was calculated from the change in the distance of the marker before and after the heat treatment obtained by the image-based motion capture 14 according to formula (1), and was evaluated according to the following criteria. ⊚: The heat shrinkage rate (A1) is within the range of 50 to less than 85%. ◯: The heat shrinkage rate (A1) is from 30 to less than 50%, or from 85% to less than 90%. Δ: The heat shrinkage rate (A1) is from 20 to less than 30%, or from 90% to less than 95%. ×: The heat shrinkage rate (A1) is less than 20% or exceeds 95%.

[0114] (3) Evaluation 3: Standard deviation (σ1) of thermal shrinkage rate in the TD direction (A1) In evaluation 2, the standard deviation (σ1) was calculated from the values ​​(n=6) of the thermal shrinkage rate in the TD direction (A1) obtained using image-based motion capture, and evaluated according to the following criteria. ⊚: The standard deviation of the thermal shrinkage rate (A1) is within 5%. ◯: The standard deviation of the thermal shrinkage rate (A1) is within 10%. △: The standard deviation of the thermal shrinkage rate (A1) is within 15%. ×: The standard deviation of the heat shrinkage rate (A1) is more than 20%.

[0115] (4) Evaluation 4: Thermal shrinkage in the TD direction (A´1) The obtained polyester shrink film was immersed in hot water at 95° C. for 10 seconds in a hot water bath to cause thermal shrinkage. Next, the dimensional changes before and after the heat treatment were calculated based on the data, and the thermal shrinkage rate (A'1) in the TD direction was calculated according to formula (1), and evaluated according to the following criteria. ⊚: The heat shrinkage rate (A´1) is within the range of 70 to 85%. ◯: The heat shrinkage rate (A'1) is from 65 to less than 70%, or from 85% to less than 90%. Δ: The heat shrinkage rate (A′1) is from 60 to less than 65%, or from 90% to less than 95%. ×: The heat shrinkage rate (A′1) is less than 60% or exceeds 95%.

[0116] (5) Rating 5: Haze The haze value of the obtained polyester shrink film was measured in accordance with JIS K 7136:2000, and evaluated according to the following criteria. ⊚: Haze value is 3% or less. ◯: Haze value is 5% or less. △: Haze value is 7% or less. ×: Haze value exceeds 7%.

[0117] (6) Evaluation 6: Thermal shrinkage in the TD direction (A2) The obtained polyester shrink film was immersed in hot water at 80° C. for 1 second in a hot water bath to cause thermal shrinkage. Next, as shown in FIG. 2(a), while capturing image data with an optical camera, the thermal shrinkage rate (A2) in the TD direction was calculated from the change in the distance of the marker before and after the heat treatment obtained by the image-based motion capture 14 according to formula (1), and was evaluated according to the following criteria. ⊚: The heat shrinkage rate (A2) is within the range of 20 to less than 50%. ◯: The heat shrinkage rate (A1) is from 15 to less than 20%, or from 50% to less than 70%. Δ: The heat shrinkage rate (A1) is from 10 to less than 15%, or from 70% to less than 80%. ×: The heat shrinkage rate (A1) is less than 10% or exceeds 80%.

[0118] (7) Evaluation 7: Standard deviation (σ2) of thermal shrinkage rate (A2) in the TD direction In evaluation 6, the standard deviation (σ2) was calculated from the values ​​(n=6) of the thermal shrinkage rate in the TD direction (A2) obtained using image-based motion capture, and evaluated according to the following criteria. ⊚: The standard deviation of the thermal shrinkage rate (A2) is within 4%. ◯: The standard deviation of the thermal shrinkage rate (A2) is within 8%. △: The standard deviation of the thermal shrinkage rate (A2) is within 12%. ×: The standard deviation of the heat shrinkage rate (A2) is more than 16%.

[0119] (8) Rating 8: Thermal shrinkage in TD direction (A´2) The obtained polyester shrink film was immersed in hot water at 80° C. for 10 seconds in a hot water bath to cause thermal shrinkage. Next, as shown in Figure 2(a), while capturing image data with an optical camera, the thermal shrinkage rate in the TD direction (A'2) was calculated from the change in the distance of the marker before and after the heat treatment obtained by image-based motion capture 14 in accordance with formula (1), and was evaluated according to the following criteria. ⊚: The heat shrinkage rate (A'2) is within the range of 30 to less than 65%. ◯: The heat shrinkage rate (A'2) is from 20 to less than 30%, or from 65% to less than 75%. Δ: The heat shrinkage rate (A′2) is from 10 to less than 20%, or from 75% to less than 85%. ×: The heat shrinkage rate (A'2) is less than 10% or exceeds 85%.

[0120] (9) Evaluation 9: Standard deviation (σ´2) of thermal shrinkage rate in the TD direction (A´2) In evaluation 8, the standard deviation (σ´2) was calculated from the thermal shrinkage rate in the TD direction (A2´) values ​​(n=6) obtained using image motion capture, and evaluated according to the following criteria. ⊚: The standard deviation of the thermal shrinkage rate (A´2) is within 2.5%. ◯: The standard deviation of the thermal shrinkage rate (A´2) is within 5%. △: The standard deviation of the thermal shrinkage rate (A´2) is within 7.5%. ×: The standard deviation of the thermal shrinkage rate (A´2) is more than 10%.

[0121] (10) Rating 10: Heat shrinkage speed The obtained polyester shrink film was floated in 80° C. hot water for 10 seconds using a hot water bath, and thermally shrunk while being measured by an image-based motion capture for 10 seconds or more. That is, while capturing image data with an optical camera, the thermal shrinkage speed in the main shrinkage direction was calculated from the change in distance of a specified marker before and after a specified time obtained by image-based motion capture, according to formula (2), and evaluated according to the following criteria. At this time, in calculating the thermal shrinkage rate speed, the distance PL0 of the predetermined section before thermal shrinkage was set to 10 mm, and measurements were taken at intervals of 0.1 seconds. ◎: The thermal shrinkage speed is 4 mm / sec or more. Good: The thermal shrinkage speed is 3 mm / sec or more and less than 4 mm / sec. △: The thermal shrinkage speed is 2 mm / sec or more and less than 3 mm / sec. ×: The thermal shrinkage speed is less than 2 mm / sec.

[0122] (11) Rating 11: Minimum intermediate heat shrink speed The obtained polyester shrink film was floated on hot water at 80° C. for 10 seconds in a hot water bath to cause thermal shrinkage. Next, while taking image data with an optical camera, the intermediate heat shrinkage speed was calculated from the heat shrinkage rate in the main shrinkage direction (number of predetermined sections n=6) obtained by image-based motion capture according to formula (4), and evaluation was performed according to the following criteria from the minimum value of the intermediate heat shrinkage speed in the section with the largest maximum value of the intermediate heat shrinkage speed among the predetermined sections. At this time, in calculating the intermediate thermal shrinkage speed, the measurement is performed with the distance PL0 of the predetermined section before thermal shrinkage set to 10 mm and the measurement period t3-t2 set to 0.1 seconds. ⊚: The minimum intermediate heat shrinkage speed is 0 mm / sec or more. ◯: The minimum intermediate heat shrinkage speed is -1.5 mm / sec or more. △: The minimum intermediate heat shrinkage speed is -2.5 mm / sec or more. ×: The minimum intermediate heat shrinkage speed is less than −2.5 mm / sec.

[0123] [Example 2] 1. Preparation of polyester shrink film In Example 2, as shown in Table 1, a raw sheet having a thickness of 200 μm was obtained in the same manner as in Example 1, except that 100 parts by weight of a non-crystalline polyester resin (PETG2) was used in the stirring vessel. Next, using a shrink film manufacturing device, a 40 μm thick polyester shrink film was produced from the original sheet at a preheating temperature of 75°C, a stretching temperature of 75°C, a stretching ratio (MD direction: 105%, TD direction: 500%), and a heat setting temperature of 60°C.

[0124] 2. Evaluation of polyester shrink film In Example 2, the thickness variation of the obtained polyester shrink film (Evaluation 1), the thermal shrinkage rate in the TD direction by image-based motion capture (Evaluation 2 and Evaluation 4), the standard deviation of the thermal shrinkage rate in the TD direction by image-based motion capture (Evaluation 3), etc. were measured and evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0125] [Comparative Example 1] 1. Preparation of polyester shrink film In Comparative Example 1, as shown in Table 1, 50 parts by weight of amorphous polyester resin (PETG3) and 50 parts by weight of amorphous polyester resin (PETG4) were used in the stirring vessel, and a raw sheet having a thickness of 200 μm was obtained in the same manner as in Example 1. Next, using a shrink film manufacturing device, a 40 μm thick polyester shrink film was produced from the original sheet at a preheating temperature of 90°C, a stretching temperature of 90°C, a stretching ratio (MD direction: 105%, TD direction: 500%), and a heat setting temperature of 60°C.

[0126] 2. Evaluation of polyester shrink film In Comparative Example 1, the thickness variation of the obtained polyester shrink film (Evaluation 1), the thermal shrinkage rate in the TD direction by image-based motion capture (Evaluation 2 and Evaluation 4), the standard deviation of the thermal shrinkage rate in the TD direction by image-based motion capture (Evaluation 3), etc. were evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0127] [Comparative Example 2] 1. Preparation of polyester shrink film In Comparative Example 2, as shown in Table 1, a raw sheet having a thickness of 200 μm was obtained in the same manner as in Example 1, except that 100 parts by weight of a non-crystalline polyester resin (PETG4) was used in the stirring vessel. Next, using a shrink film manufacturing device, a 40 μm thick polyester shrink film was produced from the original sheet at a preheating temperature of 90°C, a stretching temperature of 90°C, a stretching ratio (MD direction: 105%, TD direction: 500%), and a heat setting temperature of 60°C.

[0128] 2. Evaluation of polyester shrink film In Comparative Example 2, the thickness variation of the obtained polyester shrink film (Evaluation 1), the thermal shrinkage rate in the TD direction by image-based motion capture (Evaluation 2 and Evaluation 4), the standard deviation of the thermal shrinkage rate in the TD direction by image-based motion capture (Evaluation 3), etc. were evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0129] [Comparative Example 3] 1. Preparation of polyester shrink film In Example 2, as shown in Table 1, a raw sheet having a thickness of 200 μm was obtained in the same manner as in Example 1, except that 100 parts by weight of a non-crystalline polyester resin (PETG3) was used in the stirring vessel. Next, using a shrink film manufacturing device, a 40 μm thick polyester shrink film was produced from the original sheet at an extrusion temperature of 260°C, a preheating temperature of 90°C, a stretching temperature of 90°C, a stretching ratio (MD direction: 105%, TD direction: 500%), and a heat setting temperature of 60°C.

[0130] 2. Evaluation of polyester shrink film In Comparative Example 3, the thickness variation of the obtained polyester shrink film (Evaluation 1), the thermal shrinkage rate in the TD direction by image-based motion capture (Evaluation 2 and Evaluation 4), the standard deviation of the thermal shrinkage rate in the TD direction by image-based motion capture (Evaluation 3), etc. were evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0131] [Table 1]

[0132] [Table 2]

[0133] [Table 3] [Industrial Applicability]

[0134] According to the present invention, by using motion capture to limit at least the thermal shrinkage rate, etc. measured under specified conditions to values ​​within a specified range, it is now possible to quickly and accurately evaluate and provide polyester-based shrink films, etc. that exhibit excellent wrinkle resistance properties. Therefore, the polyester shrink film of the present invention can be applied to various PET bottles, etc., significantly expanding its versatility and thus having extremely high industrial applicability.

Claims

1. A method for measuring the thermal shrinkage rate of a polyester-based shrink film in the main shrinkage direction using motion capture, the method comprising the following steps (a) to (e): Step (a): A step of setting two measurement positions in the main shrinkage direction of the polyester shrink film as the object to be measured, and measuring the distance between the two measurement positions as L1. Step (b): Providing a predetermined marker at each of the two measurement positions. Step (c): A step of heating the polyester shrink film at a temperature and for a period of time that constitutes a predetermined heat shrinkage condition, thereby causing the film to heat shrink. Step (d): A step of measuring the distance of a predetermined interval after thermal shrinkage, designated as L'1, using the motion capture device. Step (e): A step of calculating the thermal shrinkage rate in the TD direction, which is the main shrinkage direction of the polyester-based shrink film, based on the following formula (1). [0010]

2. The method for measuring the heat shrinkage of a polyester shrink film according to claim 1, characterized in that the distance between the two measurement positions in step (a) is set to multiple values, and multiple heat shrinkage values ​​in the TD direction are calculated in steps (d) to (e), and the average value thereof is used as the heat shrinkage value in the TD direction.

3. A method for measuring the thermal shrinkage rate of a polyester-based shrink film as described in claim 1 or 2, characterized in that the motion capture is an image-based motion capture, and the thermal shrinkage rate in the TD direction is calculated based on the positions of the specified markers before and after thermal shrinkage.

4. A method for measuring the thermal shrinkage rate of a polyester-based shrink film as described in claim 1 or 2, characterized in that in step (b), a camera is provided to simultaneously observe the thermal shrinkage state of the polyester-based shrink film as the object to be measured.

5. The method for measuring the heat shrinkage rate of a polyester shrink film according to claim 1 or 2, characterized in that the heat shrinkage temperature in the step (c) is set to a value within the range of 50 to 98°C, and the heat shrinkage time is set to a value within the range of 1 to 60 seconds.

6. 3. The method for measuring the heat shrinkage rate of a polyester shrink film according to claim 1 or 2, characterized in that the heat shrinkage device in step (c) is at least one of a thermostatic bath, a steam bath, a hot water bath, a fluorine-containing liquid bath, and an infrared ray irradiation device.

7. A method for measuring the thermal shrinkage rate of a polyester-based shrink film as described in claim 1 or 2, characterized in that in step (d), the thermal shrinkage rate in a direction perpendicular to the main shrinkage direction of the polyester-based shrink film as the measured object is measured as the thermal shrinkage rate in the MD direction using the motion capture device simultaneously with the measurement of the thermal shrinkage rate in the TD direction.

8. 3. The method for measuring the heat shrinkage rate of a polyester-based shrink film according to claim 1 or 2, further comprising, after the step (e), a step (f) of preparing a calibration curve showing the relationship between the heat shrinkage temperature and heat shrinkage time in the main shrinkage direction of the polyester-based shrink film as the object to be measured, and the heat shrinkage rate in the TD direction, and comparing and verifying the calibration curve with the heat shrinkage rate obtained based on formula (1).

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