Polyester shrink film

Abstract

Provided is a polyester-based shrink film having a predetermined heat shrinkage rate in a main shrinkage direction etc. as measured using motion capture.　The polyester-based shrink film having a predetermined heat shrinkage rate as measured using motion capture is characterized in that, when two measurement positions are set in the main shrinkage direction, the distance between the two measurement positions is L, and the distance measured using motion capture after heat shrinkage is L'1, the heat shrinkage rate (temperature: 70-98°C, time: 1-60 seconds), based on the distance between L1 and L'1 etc., in the main shrinkage direction is 20% or more.

Description

Technical Field

[0001] The present invention relates to a polyester shrink film. More specifically, the present invention relates to a polyester shrink film having a predetermined heat shrinkage rate and the like that is measured quickly and accurately using motion capture.

Background Art

[0002] Conventionally, shrink films have been widely used as base films for labels such as PET bottles. In particular, polyester resins are excellent in transparency and strength and are widely used. These shrink films are heat-shrunk by passing them through a tunnel that generates hot air or steam and then attached to containers. However, shrinkage differences (non-uniformities) may occur during heat shrinkage, resulting in the occurrence of wrinkles and color non-uniformities. Therefore, various heat-shrinkable polyester films have been proposed to prevent the occurrence of shrinkage differences (non-uniformities) and the resulting wrinkles and color non-uniformities during heat shrinkage.

[0003] For example, heat-shrinkable polyester films have been proposed in which the ratio of alcohol components other than ethylene glycol is controlled, or the amount of naphthalenedicarboxylic acid component and the blending amount of the alkali metal salt of sulfobenzenedicarboxylic acid in the total acid component are strictly controlled (see Patent Document 1). More specifically, the polyester resin has a ratio of acid components other than terephthalic acid in the total acid component (A mol%) and a ratio of alcohol components other than ethylene glycol in the total alcohol component (B mol%) within the range of 5 mol% ≤ A + B ≤ 40 mol%, and contains a naphthalenedicarboxylic acid component in the total acid component at a ratio of 1 to 30 mol% and an alkali metal salt of sulfobenzenedicarboxylic acid at a ratio of 0.3 to 3 mol%. Regarding the heat shrinkage rate of such a polyester film, in the longitudinal direction of the film, it is preferably 5% or more in warm water immersion at a temperature of 60°C for 60 seconds, and 30% or more in warm water immersion at a temperature of 80°C for 60 seconds.

[0004] Furthermore, 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 shrinkage rate at 80°C and 90°C in the longitudinal direction of the film, as well as the hot water shrinkage rate at 90°C in the width direction of the film, is limited (see Patent Document 2). More specifically, a heat-shrinkable polyester film in which ethylene terephthalate is the main component and one or more monomer components that can become amorphous components in the total polyester resin components, with the total amount of these monomer components being 15 mol% or more. Furthermore, the polyester film is characterized by a hot water shrinkage rate of 30% or more in the longitudinal direction of the film at a processing temperature of 80°C and a processing time of 10 seconds, and 40% or more at a processing temperature of 90°C and a processing time of 10 seconds, while the hot water shrinkage rate in the width direction of the film is 10% or less at a processing temperature of 90°C and a processing time of 10 seconds.

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

[0006] Furthermore, shrink labels that specify the maximum thermal shrinkage rate measured under predetermined conditions have been proposed (see Patent Document 4). More specifically, the heat-shrinkable shrink label comprises at least one film layer in which a polylactic acid polymer is an essential component, and a printed layer. Furthermore, it is characterized by a thermal shrinkage rate in the main orientation direction of 3-23% one second after the start of thermal shrinkage in 75°C hot water, and a thermal shrinkage rate in the main orientation direction of 40-84% at 90°C for 10 seconds. Alternatively, it is characterized by a maximum thermal shrinkage rate of 7-40% / second in the main orientation direction in 75°C hot water, and furthermore, a thermal shrinkage rate of 40-84% in the main orientation direction at 90°C for 10 seconds. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 08-027259 (Claims, etc.) [Patent Document 2] Japanese Patent Publication No. 2007-016120 (Claims, etc.) [Patent Document 3] Japanese Patent Publication No. Hei 8-323859 (Claims, etc.) [Patent Document 4] Japanese Patent Publication No. 2008-1098 (Claims, etc.) [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, in the heat-shrinkable films described in Patent Documents 1 and 2, although the heat shrinkage rate at a predetermined temperature and in a predetermined shrinkage direction is limited to a predetermined range, it is necessary to measure the film after immersing it in hot water and then removing it from the hot water. This can easily lead to uneven heat distribution and large variations in the measured values. Consequently, polyester films with such measured heat shrinkage rates were difficult to obtain with the desired heat shrinkage rate, and it was sometimes impossible to quickly and accurately control the heat shrinkage characteristics. Therefore, in particular, with PET bottles where the diameter of the body is not uniform, and where the horizontal cross-sectional shape of the body is not circular in some parts but has a complex shape, the thermal shrinkage tends to be uneven, making it extremely difficult to suppress the occurrence of fine wrinkles.

[0009] Furthermore, while the heat-shrinkable film described in Patent Document 3 specifies the change in the rate of heat shrinkage with respect to time, it specifies the averaged heat shrinkage rate coefficient (% / (second·°C)) before and after heat shrinkage, and does not intend to measure the maximum value of the heat shrinkage rate (mm / second) from before heat shrinkage to a predetermined time. Therefore, it was not possible to accurately measure the thermal shrinkage rate (mm / second) at the moment when the heat-shrinkable film undergoes a large change in a short period of time during thermal shrinkage.

[0010] Furthermore, while Patent Document 4 specifies the thermal shrinkage rate (%) at 1 second after the start of thermal shrinkage, it is a thermal shrinkage rate limited to a specific time, and does not address shrinkage labels with different thermal shrinkage timings. Furthermore, although the maximum thermal shrinkage rate (% / sec) is mentioned, it is actually the instantaneous thermal shrinkage rate measured at 0.1-second intervals, and there was no intention to measure the maximum thermal shrinkage rate (mm / sec) from before thermal shrinkage to a predetermined time. Therefore, when converted to the maximum value of the thermal shrinkage rate from before thermal shrinkage to a predetermined time, it was limited to a very small range.

[0011] Therefore, the inventors of the present invention have discovered that by using motion capture to measure the thermal shrinkage rate in the main shrinkage direction and controlling that value, the thermal shrinkage characteristics can be managed quickly and accurately, thus completing the present invention. In other words, the present invention aims to provide a polyester shrink film having a predetermined heat shrinkage rate in the main shrinkage direction, etc., which can be measured quickly and accurately using a predetermined simple measurement method.

Means for Solving the Problem

[0012] The present invention is a polyester shrink film having a predetermined heat shrinkage rate, which is obtained by using motion capture. And, in the TD direction, which is the main shrinkage direction of the polyester shrink film as the object to be measured, two measurement positions are set, the distance between the two measurement positions is set as L1, and when the distance between the two measurement positions after heat shrinking the polyester shrink film is set as L'1, which is measured by using motion capture, a polyester shrink film is provided in which the heat shrinkage rate (temperature: 70 to 98 °C, time: from 1 to 60 seconds) in the main shrinkage direction of the polyester shrink film, calculated based on the following formula (1), is 20% or more, and the above-described problem can be solved.

[0013]

Number

[0014] That is, by using motion capture and using a corresponding inertial sensor or infrared light to measure the moving distance of a predetermined location, the heat shrinkage rate at the predetermined location can be calculated quickly and accurately.

[0015] Moreover, when constituting the polyester shrink film of the present invention, it is preferable that the standard deviation of the heat shrinkage rate is 15% or less. This is because by controlling the standard deviation of the heat shrinkage rate, the heat shrinkage rate of the polyester shrink film can be controlled more accurately.

[0016] Moreover, when constituting the polyester shrink film of the present invention, the thickness of the polyester shrink film is in the range of 10 to 200 μm, and it is preferable that the difference between the maximum value of the thickness and the average value of the thickness is within 10 μm. Thus, by controlling the thickness of the polyester shrink film, the difference between the maximum value of the thickness in the TD direction and the average value of the thickness becomes smaller, and thus, the heat shrinkage rate in the TD direction can be controlled more quickly and accurately.

[0017] In addition, when constructing the polyester shrink film of the present invention, it is preferable to set a plurality of measurement positions at two positions and use the average value of the heat shrinkage rates in the TD direction obtained at the plurality of positions as the heat shrinkage rate in the TD direction. Thus, by calculating the heat shrinkage rates in the TD direction at a plurality of positions, the heat shrinkage rate in the TD direction can be controlled more quickly and accurately.

[0018] In addition, when constructing the polyester shrink film of the present invention, it is preferable that the motion capture is an image-based motion capture that detects information of a predetermined marker. Thus, by selecting and using an image-based motion capture from among various types of motion captures, the position of the predetermined marker can be efficiently calculated, and the heat shrinkage rate can be measured quickly and accurately.

[0019] In addition, when constructing the polyester shrink film of the present invention, it is preferable that the motion capture includes a camera for recording the heat shrinkage state of the polyester shrink film. Thus, by also considering the image data indicating the heat shrinkage state photographed by the camera, the heat shrinkage state in the TD direction can be correctly confirmed, and thus, the heat shrinkage rate and the like in the TD direction can be measured more quickly and accurately.

[0020] In addition, when constructing the polyester shrink film of the present invention, it is preferable that the heat shrinkage rate of the polyester shrink film is based on at least one of a constant temperature bath, a steam bath, a warm water bath, a fluorine-containing liquid bath, and an infrared irradiation device. By using such a heat shrinkage device for measurement, the heat shrinkage rate can be controlled more quickly, accurately, and simply, depending on the application of the polyester shrink film.

[0021] Furthermore, when constructing the polyester shrink film of the present invention, it is preferable to define the direction perpendicular to the main shrinkage direction of the polyester shrink film as the object to be measured as the MD direction, and to measure the thermal shrinkage rate in the MD direction using motion capture simultaneously with the measurement of the thermal shrinkage rate in the TD direction, and to set the thermal shrinkage rate in the MD direction to a value within the range of -5 to 5%. In this way, by simultaneously measuring the thermal shrinkage rate in the MD direction using motion capture, it is possible to control the thermal shrinkage characteristics of the polyester shrink film when it is actually used, depending on the application of the polyester shrink film.

[0022] Furthermore, when constructing the polyester shrink film of the present invention, it is preferable to first create a calibration curve showing the relationship between the heat shrinkage temperature and heat shrinkage time in the main shrinkage direction of the polyester shrink film as the object to be measured, and the heat shrinkage rate in the TD direction, and then compare and verify the calibration curve with the heat shrinkage rate obtained based on formula (1), and set the heat shrinkage rate obtained based on formula (1) to a value within ±10% of the heat shrinkage rate in the TD direction obtained from the calibration curve. In this way, by comparing the measured thermal shrinkage rate against a pre-created calibration curve, it is possible to produce a polyester shrink film with a thermal shrinkage rate that is more rapid, accurate, and reproducible, even when using motion capture. [Brief explanation of the drawing]

[0023] Figures 1(a) to 1(c) are diagrams illustrating the morphology of polyester shrink film. Figures 2(a) to 2(c) illustrate a method for measuring the thermal shrinkage rate of polyester shrink film using motion capture or the like. Figures 3(a) and 3(b) illustrate the positional shift of a predetermined marker due to the thermal shrinkage of a polyester shrink film. Figures 4(a) and 4(b) are provided to illustrate a method for measuring the thermal shrinkage rate of a polyester shrink film using motion capture or the like. Figures 5(a) to 5(c) illustrate examples of the configuration of a fixing jig used in measuring thermal shrinkage rate using motion capture. Figures 6(a) and 6(b) are provided to explain the thermal shrinkage rate and thermal shrinkage coefficient. Figure 7 is provided to illustrate the relationship between time (seconds) and the change in distance (mm) over a predetermined interval in the polyester shrink films of Examples 1-2 and Comparative Examples 2-3. Figures 8(a) and 8(b) illustrate the relationship between time (seconds) and the thermal shrinkage rate (mm / second) in the polyester shrink films of Examples 1 and 2, while Figure 8(c) illustrates the relationship between time and the thermal shrinkage rate (% / second). Figures 9(a) and 9(b) illustrate the relationship between time (seconds) and the thermal shrinkage rate (mm / second) in the polyester shrink films of Comparative Examples 2 and 3, while Figure 9(c) illustrates the relationship between time and the thermal shrinkage rate (% / second). Figure 10(a) is provided to illustrate the relationship between the intermediate heat shrinkage rate (mm / sec) and time (seconds) in the polyester shrink film of Example 1, and Figure 10(b) is provided to illustrate the relationship between the intermediate heat shrinkage rate (% / sec) and time. Figure 11(a) is provided to illustrate the relationship between the intermediate heat shrinkage rate (mm / sec) and time (seconds) in the polyester shrink film of Example 2, and Figure 11(b) is provided to illustrate the relationship between the intermediate heat shrinkage rate (% / sec) and time. Figure 12(a) is provided to illustrate the relationship between time (seconds) and the intermediate thermal shrinkage rate (mm / second) in the polyester shrink film of Comparative Example 2, and Figure 12(b) is provided to illustrate the relationship between time and the intermediate thermal shrinkage rate (% / second). Figure 13(a) is provided to illustrate the relationship between time (seconds) and the intermediate heat shrinkage rate (mm / second) in the polyester shrink film of Comparative Example 3, and Figure 13(b) is provided to illustrate the relationship between time and the intermediate heat shrinkage rate (% / second). Figure 14(a) is a diagram illustrating 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 illustrating the state in which a motion capture device is attached to one of the measurement samples (W, C, E). Figure 15 is provided to illustrate the relationship between the immersion time and the thermal shrinkage rate (%) in the TD direction, measured using motion capture, when the materials were immersed in 95°C hot water for 1 to 20 seconds in Example 1 (Line A) and Comparative Example 1 (Line B), respectively. Figure 16 illustrates 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. Figure 17(a) corresponds to Example 1 and is a diagram (photograph) showing the appearance of a tubular label when no wrinkles have occurred. Figures 17(b) to (d) are enlarged views of the areas P, Q, and R shown in Figure 17(a). Figure 18(a) corresponds to Comparative Example 1 and is a diagram (photograph) showing the appearance of a tubular label when wrinkles occur. Figures 18(b) to (d) are enlarged views of the areas S, T, and U of the appearance shown in Figure 18(a), respectively. [Modes for carrying out the invention]

[0024] [First Embodiment] The first embodiment is a polyester shrink film 10 as illustrated in Figure 1, which is a polyester shrink film having a predetermined heat shrinkage rate, as shown in Figures 2(a) to (c), using motion capture 14. As shown in Figure 3, when two measurement positions are set in the TD direction, which is the main shrinkage direction of the polyester shrink film as the object to be measured, and the distance between the two measurement positions is defined as L1, and the distance between the two measurement positions after the polyester shrink film has been heat-shrinkn is measured using motion capture and defined as L'1, the heat shrinkage rate in the main shrinkage direction of the polyester shrink film (temperature: 70~98°C, time: 1~60 seconds), calculated based on the following formula (1), is 20% or more.

[0025]

number

[0026] The polyester shrink film of the first embodiment will be described in detail below, referring to the drawings as appropriate, and broken down into its components.

[0027] 1. Polyester resin The type of polyester resin constituting the polyester shrink film of the first embodiment is not limited, but it is generally preferable to use a polyester resin composed of a polyalcohol and a dicarboxylic acid, a polyester resin composed of a polyalcohol and a hydroxycarboxylic acid, a polyester resin composed of a polyalcohol dicarboxylic acid and a hydroxycarboxylic acid, or a mixture thereof of these polyester resins.

[0028] Here, examples of polyalcohols that are compound components of polyester resin include at least one diol such as aliphatic diols like ethylene glycol, diethylene glycol, propanediol, butanediol, neopentyl glycol, and hexanediol, alicyclic diols like 1,4-hexanedimethanol, and aromatic diols. Therefore, among these, ethylene glycol, diethylene glycol, and 1,4-hexanedimethanol are particularly preferred.

[0029] Furthermore, it is more preferable to use a mixture containing at least ethylene glycol as the polyalcohol. By limiting the type of polyalcohol, which is one of the polymerization components of polyester resin, the proportion of amorphous material can be adjusted, and consequently, good fit can be obtained. Furthermore, when preparing a mixture containing a predetermined amount of ethylene glycol, it is preferable to use at least one other polyalcohol other than ethylene glycol, such as a diol having an alicyclic structure like 1,4-cyclohexanedimethanol, aliphatic diols like diethylene glycol, propanediol, butanediol, neopentyl glycol, hexanediol, or aromatic diols. This is because using such polyalcohols makes it easier to obtain amorphous polyester resins with controlled crystallinity / amorphous properties by reacting them appropriately with polycarboxylic acids.

[0030] Furthermore, examples of dicarboxylic acids as compound components of polyester resins include fatty acid dicarboxylic acids such as adipic acid, sebacic acid, and azelaic acid; aromatic dicarboxylic acids such as terephthalic acid, naphthalenedicarboxylic acid, and isophthalic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; or at least one of these ester-forming derivatives. And among these, terephthalic acid is particularly preferred. Furthermore, at least one of the following can be used as a hydroxycarboxylic acid compound component of polyester resin: lactic acid, hydroxybutyric acid, polycaprolactone, etc.

[0031] Furthermore, it is also preferable to use amorphous polyester resin in part or all as the polyester resin. For example, terephthalic acid can be suitably used in amorphous polyester resins comprising at least 80 mol% of a dicarboxylic acid, 50-80 mol% of ethylene glycol, and 20-50 mol% of one or more diols selected from 1,4-cyclohexanedimethanol, neopentyl glycol, and diethylene glycol. If necessary, other dicarboxylic acids and diols, or hydroxycarboxylic acids, may be used to change the properties of the film. These may be used individually or in mixtures.

[0032] On the other hand, crystalline polyester resins include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, and polypropylene terephthalate, which may be used individually or in mixtures.

[0033] Furthermore, if the polyester resin is a mixture of amorphous polyester resin and crystalline polyester resin, it is preferable to incorporate a predetermined amount of amorphous polyester resin into the resin constituting the polyester shrink film in order to obtain good heat resistance, shrinkage rate, etc. In other words, the amount of amorphous polyester resin blended with respect to the total amount (100% by weight) of resin constituting the polyester shrink film is usually preferably in the range of 70 to 100% by weight, preferably in the range of 80 to 98% by weight, and more preferably in the range of 85 to 95% by weight.

[0034] 2. Thermal shrinkage rate measured using motion capture (1) Basic configuration The thermal shrinkage rate in the primary shrinkage direction, calculated using motion capture, is typically determined by measuring at least two measurement positions in the TD direction, which is the primary shrinkage direction of the polyester shrink film being measured, before and after thermal shrinkage, using inertial sensors or optical methods, and then calculating the thermal shrinkage rate from the distance traveled. In other words, motion capture, along with corresponding inertial sensors and infrared sensors, is used to measure the change in distance between two measurement points, and then the thermal contraction rate is calculated from that data. More specifically, the distance between the two measurement positions is defined as L1, and the distance between the predetermined positions after thermal shrinkage is performed under predetermined thermal shrinkage conditions, namely a predetermined thermal shrinkage temperature and predetermined thermal shrinkage time, is measured using motion capture and defined as L'1. The thermal shrinkage rate is then calculated based on the above-mentioned equation (1). Furthermore, the polyester shrink film of the present invention is characterized in that the predetermined heat shrinkage rate (temperature: 70-98°C, time: 1-60 seconds) is 20% or more. The reason for this is that having such a predetermined heat shrinkage rate allows for rapid and accurate control of the heat shrinkage characteristics of the polyester shrink film. Therefore, it is preferable that the predetermined thermal shrinkage rate (temperature: 70-98°C, time: 1-60 seconds) be a value between 30% and less than 95%, preferably within the range of 40% and less than 90%, and even more preferably between 50% and less than 85%.

[0035] Furthermore, the value of L1 (mm) between the two measurement positions should preferably be selected appropriately depending on the size of the polyester shrink film and the type of motion capture, but it is preferable to set it to a value within the range of 3 to 300 mm. The reason for this is that, with this spacing, the difference in spacing before and after shrinkage of the film can be clearly recognized, allowing for faster and more accurate measurement of the thermal shrinkage rate in the TD direction. Therefore, it is more preferable to set the interval L1 (mm) of the measurement positions to a value within the range of 5 to 100 mm, and even more preferable to set it to a value within the range of 8 to 30 mm.

[0036] Furthermore, the measurement location is the area that indicates the positional information of the coordinates placed on the polyester shrink film in order to measure the behavior of the polyester shrink film during heat shrinkage. In other words, as shown in Figures 4(a) to 4(b), it is preferable that a predetermined marker such as a dot, line, cross, circle, arrow, L-shape, T-shape, or checkmark is marked as a predetermined interval M between two measurement positions. The reason for this configuration is that it allows the shrinking of the polyester shrink film to be easily observed from the surroundings.

[0037] (2) Thickness variation Furthermore, it has been found that the thermal shrinkage rate in the TD direction, measured using motion capture, may be affected by the thickness of the polyester shrink film. Therefore, it is preferable to set the thickness of the polyester shrink film to a range of 10 to 200 μm, and to keep the difference between the maximum thickness and the average thickness (hereinafter sometimes referred to as thickness variation) within 10 μm. The reason for this is that by controlling the thickness and thickness variations of the polyester shrink film, it becomes easier to control the thermal shrinkage rate in the TD direction, and consequently, the thermal shrinkage rate in the TD direction can be controlled more quickly and accurately.

[0038] However, if the variation in thickness becomes excessively small, the manufacturing yield may become extremely low, which can be economically disadvantageous. Therefore, it is more preferable to have a thickness variation within the range of 0.01 to 5 μm, and even more preferable to have a thickness variation within the range of 0.1 to 3 μm. The thickness of the polyester shrink film is usually in the range of 10 to 200 μm, but it is more preferable to have a thickness in the range of 20 to 100 μm, and even more preferable to have a thickness in the range of 30 to 60 μm.

[0039] Furthermore, regarding the variation in the thickness of the polyester shrink film, it is preferable to select multiple different locations (for example, n=3 to 30 locations) on the same film and calculate the variation based on the maximum and average values ​​of the measured thicknesses. The reason for this is that by calculating the thickness in this way, the film can be evaluated more quickly and accurately. Therefore, it is more preferable to select 4 to 20 different measurement positions on the same film, and even more preferable to select 5 to 10 measurement positions.

[0040] (3) Thermal contraction rate at multiple locations Furthermore, it is preferable to set multiple intervals between the two measurement positions, calculate the thermal shrinkage in the TD direction at multiple locations, and use the average value as the thermal shrinkage rate in the TD direction. In other words, it is preferable to select multiple different locations on the same film (for example, n=3 to 30 locations), and use the average value of the measured thermal shrinkage rates (temperature: 70 to 98°C, time: 1 to 60 seconds) as the thermal shrinkage rate in the TD direction. The reason for this is that by calculating the thermal contraction in the TD direction at multiple locations, the thermal contraction 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 even more preferable to select 5 to 10 measurement positions.

[0041] (4) Standard deviation of thermal shrinkage coefficient in the TD direction (σ1) Furthermore, when a polyester shrink film is heat-shrunk under predetermined conditions of temperature and time, it is preferable that the standard deviation of the thermal shrinkage rate in the TD direction be within 15%. The reason for this is that by using such a standard deviation, the thermal shrinkage rate of polyester shrink film can be controlled with greater precision. Therefore, it is more preferable to have a standard deviation of 10% or less in the thermal shrinkage rate in the TD direction, and even more preferable to have a standard deviation of 5% or less.

[0042] (5) Motion capture 1) Basic configuration Preferably, the interval between measurement positions in polyester shrink film is calculated based on positional information of the measurement positions obtained by motion capture. The reason for this is that by using this type of motion capture, the intervals between measurement positions on the film can be acquired quickly and accurately as digital data. Here, motion capture is a technology that converts the movement of an object to be measured into digital data, and primarily involves tracking the position of a predetermined marker on the object to be measured and recording it as coordinate data.

[0043] Specifically, while there are no particular limitations on the types of motion capture, image-based motion capture, inertial motion capture, optical motion capture, or combinations thereof, any of these motion capture methods can be used. However, in the case of polyester shrink film, since it is heat-treated by immersion in hot water, etc., there are many space limitations, and it is preferable to use image-based or inertial motion capture because it is easier to miniaturize and simplify the device.

[0044] Therefore, as shown in Figure 2(a), it is preferable to use an optical camera as an image-based motion capture 14 to capture a video of the heat shrinkage of the polyester shrink film 10 as the object to be measured, and to measure the heat shrinkage rate by performing image analysis on the acquired data. In other words, it is preferable that the polyester shrink film has a configuration in which multiple scales (for example, 2 to 30 lines) are pre-marked at intervals L1 using a predetermined marker such as an oil-based marker. Next, it is preferable to place the polyester shrink film on a flat surface and use an optical camera to capture video footage of the process before and after thermal shrinkage from vertically above. Furthermore, it is preferable that the system is configured to calculate the interval between each scale mark before thermal shrinkage from the relationship between the number of pixels and the actual measurement, based on the data of the captured video, and to use the average value of these intervals as the thermal shrinkage rate. Specifically, for example, in a configuration where scales are arranged on the left and right, it is preferable to draw horizontal imaginary lines that intersect each scale, and to define the measurement position as the point where the scale and the imaginary line intersect. The reason for this is that by continuously recording the thermal contraction state as video data, the thermal contraction rate in the TD direction can be measured more quickly, accurately, and efficiently. Furthermore, by recording the data in this way, the device can be made smaller and simpler, even in situations with many spatial constraints, and the thermal shrinkage rate can be measured more efficiently. The type of marker should be such that it is easily visible to an optical camera, but it is preferable that it is composed of, for example, an oil-based marker or grooves.

[0045] Furthermore, it is preferable that the motion capture system is configured as an inertial position measuring device that obtains information on acceleration, angular velocity, and direction from inertial sensors attached to a polyester shrink film, and uses a device such as an IMU to accurately determine the position of a marker (such as the center of gravity). In other words, it is preferable to have an inertial motion capture system equipped with a 9-axis inertial sensor that combines an accelerometer and an angular velocity meter (gyro sensor), and further combines these with a geomagnetic sensor.

[0046] On the other hand, it is also preferable to use optical motion capture as the motion capture method. In other words, it is preferable that the device is a type of optical position measuring device that uses motion capture to irradiate an optical marker (such as a retrospective marker) with radiation such as infrared light and detects the reflected light. Furthermore, this motion capture system performs predetermined image processing based on the obtained reflected light, enabling the two-dimensional identification of the marker's position (such as the center of gravity). Moreover, by using multiple motion capture systems in combination, it is a measurement device capable of three-dimensional position identification.

[0047] 2) Use of optical camera Furthermore, as shown in Figures 2(b) to (c), it is preferable to use predetermined optical cameras 14a and 14b in conjunction with the inertial motion capture 14 to simultaneously capture the thermal shrinkage state of the polyester shrink film 10, and to use this as image data for reference when measuring the thermal shrinkage rate. The reason for this is that by continuously recording the thermal contraction state in conjunction with camera images, the state of thermal contraction in the TD direction can be confirmed as image data, and consequently, the thermal contraction 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 heat shrinkage state of the polyester shrink film from the front, side, top, back, or oblique angles of the polyester shrink film being measured.

[0048] 3) Thermal shrinkage conditions It is preferable to set the temperature for thermal contraction conditions to a value within the range of 70 to 98°C, and the time to a value within the range of 1 to 60 seconds. The reason for this is that by using these heat shrinkage conditions, it is possible to easily compare and verify the heat shrinkage characteristics of polyester shrink film when it is actually used. Therefore, as thermal shrinkage conditions, it is more preferable to set the thermal shrinkage temperature to a value in the range of 75 to 95°C and the thermal shrinkage time to a value in the range of 5 to 30 seconds, and even more preferable to set the thermal shrinkage temperature to a value in the range of 80 to 90°C and the thermal shrinkage time to a value in the range of 8 to 15 seconds, since these conditions approximate practical thermal shrinkage conditions and can be measured in a relatively short time. Furthermore, it has been found that by improving the accuracy of motion capture, the thermal shrinkage rate of polyester shrink film can be accurately measured even within a range of 1 to 5 seconds, or even within a range of 1 to 3 seconds.

[0049] 4) Heat shrinking machine The heat shrinkage apparatus is preferably comprised of at least one of a constant temperature bath (oven), a steam bath, a hot water bath, a hot air heater, a liquid bath containing a fluorine-containing compound, a steam bath containing a fluorine-containing compound, and an infrared irradiation device. The reason for this is that when motion capture is used, various heat shrinkage devices can be used depending on the application of the polyester shrink film, and consequently, the heat shrinkage rate can be measured more quickly, accurately, and simply.

[0050] Furthermore, as an example, it is preferable to use a hot water bath as the heat shrinking device. The reason for this is that using such a heat shrink device makes it easy to maintain a constant temperature of hot water, and allows for more precise control of the heat shrink temperature. Furthermore, by using a hot water bath, the polyester shrink film can be floated and heated uniformly and evenly, making it easier to capture the behavior of the polyester shrink film during thermal shrinkage from above using an optical camera or the like.

[0051] Specifically, while a single motion capture device allows for the measurement and calculation of thermal shrinkage from two-dimensional measurement points, using multiple motion capture devices offers the advantage of being able to measure the three-dimensional positional relationships of measurement points and then measure and calculate the thermal shrinkage.

[0052] For example, even when a flat hot plate is used as a heat shrinkage device, the heat shrinkage rate can be easily and quickly measured in three dimensions, not only horizontally but also when it is tilted along the direction of gravity or positioned vertically parallel to the direction of gravity. Therefore, by using one or more motion capture devices, various heat shrinkage devices can be used, making it possible to measure the heat shrinkage rate more easily and quickly depending on the application of the polyester shrink film.

[0053] Furthermore, 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 that blows air supplied by a compressed air pump or fan onto an object via a heat source such as an electric heating element or an oil heater as a hot air heater. Specifically, for example, the heat shrink device is preferably configured to heat shrink a polyester shrink film that is placed planarly on a belt conveyor or a platform by blowing hot air from vertically above the polyester shrink film. The reason for this is that using such a heat shrink device increases the flexibility of its placement, allowing it to be positioned above the polyester shrink film manufacturing equipment, and enabling easier in-line measurement of the heat shrinkage rate by blowing hot air onto the cut-off edges. Therefore, when using a hot air heater in this manner, it is preferable that the polyester shrink film is configured to receive the hot air within a tunnel-shaped enclosure made of stainless steel, aluminum, glass, or the like, from the viewpoint of effectively transferring the heat of the hot air to the polyester shrink film.

[0054] 5) Fixing jig Furthermore, as shown in Figures 2(a) to (c), it is preferable to prepare a hot water bath 20 containing hot water 22 maintained at a predetermined temperature by a heater 22a, and to immerse the polyester shrink film 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 causing it to heat shrink in the main shrinkage direction. In this case, as shown in Figures 2(a) to (b), it is preferable to prepare a mesh-like fixing jig 12 made of stainless steel wire or the like, and partially house the polyester shrink film 10 inside it.

[0055] Furthermore, when heat-shrinking a polyester shrink film, it is preferable to use a frame-shaped fixing jig that maintains the posture of the polyester shrink film without hindering its shrinkage. In other words, as illustrated in Figures 5(a) to (c), the fixing jig 12 is preferably composed of a frame member and includes at least a mounting portion 13a for placing and holding the polyester shrink film, a guide portion 13b for controlling the shrinkage direction of the polyester shrink film, and a restricting portion 13c to prevent slippage during thermal shrinkage. Furthermore, from the viewpoint of improving handling, it is preferable that the fixing jig 12 is positioned at least at the end of the mounting portion 13a in the main contraction direction and is provided with a handle portion 13d that protrudes diagonally upward. Specifically, the fixing jig is preferably made of metal wires such as stainless steel, iron, aluminum, or copper, or frame members such as resin. The reason for this configuration is that it allows for stable placement of the polyester shrink film, reduces vibration during thermal shrinkage, and enables more accurate measurement of the thermal shrinkage rate.

[0056] Furthermore, from the viewpoint of ease of handling and uniform heating of the polyester shrink film, the mounting section is preferably a substantially flat, frame-like portion, and when viewed from above in a plan view, it preferably consists of at least two rail-like portions parallel to the main shrinkage direction. Furthermore, the guide portion is preferably positioned parallel to the mounting portion when viewed from a plan view from vertically above, and is a portion that is curved in a wave-like manner vertically. In addition, the restricting section is positioned perpendicular to the main shrinkage direction, bridging the guide section, and is a part that can move up and down along the frame of the guide section, and is the part that sandwiches the polyester shrink film placed on the mounting section between the mounting section and the restricting section. The reason for this configuration is that, by configuring it in this way, displacement of the polyester shrink film during thermal shrinkage is prevented, and the center position of the shrinkage is stabilized, allowing for accurate measurement of the thermal shrinkage rate using motion capture. Furthermore, by curving the guide section in a wave-like shape, for example, when using a hot water bath as a heat shrinking device during thermal shrinkage, it is possible to land the device in the water without creating waves, and by matching the height of the guide section to the water level, it becomes possible to place it at the bottom of the water bath and take measurements.

[0057] 6) Thermal shrinkage rate in the MD direction It is preferable to measure the thermal shrinkage rate (B1) of the polyester shrink film under test in a direction perpendicular to the main shrinkage direction, as the thermal shrinkage rate in the MD direction, simultaneously with the measurement of the thermal shrinkage rate in the TD direction, using motion capture. In this way, by simultaneously measuring the thermal shrinkage rate in the MD direction using motion capture, it is possible to compare it with the thermal shrinkage characteristics of polyester shrink film when actually using it, depending on the application of the polyester shrink film. Furthermore, it is preferable that the thermal shrinkage rate in the MD direction be within the range of -5 to 5%.

[0058] 7) Calibration curve It is preferable to first create a calibration curve showing the relationship between the heat shrinkage temperature and heat shrinkage time in the main shrinkage direction of the polyester shrink film to be measured, and the heat shrinkage rate in the TD direction obtained using motion capture, and then compare and verify this calibration curve with the heat shrinkage rate obtained based on equation (1). In this way, by comparing with a pre-created calibration curve, it is possible to produce a polyester-based shrink film with a heat shrinkage rate that is faster, more accurate, and more reproducible.

[0059] 3. Thermal properties of polyester shrink film, etc. (1) Configuration (a) The polyester shrink film to be measured preferably has a configuration (a) such that, in the polyester shrink film of the first embodiment, the main shrinkage direction is the TD direction, and the heat shrinkage rate A1 when shrunk in the TD direction under the conditions of a temperature of 95°C and 1 second is a value of 30 to less than 95%. The reason for this is that by limiting the 95°C heat shrinkage rate A1 to less than 30-95%, a good heat shrinkage rate can be obtained in the polyester shrink film during heat shrinkage, and consequently, the maximum shrinkage stress can be more easily obtained. Therefore, as configuration (a), it is more preferable that the 95°C heat shrinkage rate A1 be in the range of 40 to less than 90%, and even more preferable that it be in the range of 50 to less than 85%.

[0060] Furthermore, it is preferable that the polyester shrink film to be measured has a configuration (a') in which the main shrinkage direction is the TD direction, and the thermal shrinkage rate A'1 when shrunk in the TD direction under the conditions of a temperature of 95°C and 10 seconds is a value in the 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 60-95%, a good heat shrinkage rate can be obtained in the polyester shrink film during heat shrinkage, and consequently, the maximum shrinkage stress can be more easily obtained. Therefore, as configuration (a'), it is more preferable that the 95°C heat shrinkage rate A'1 be in the range of 65 to less than 90%, and even more preferable that it be in the range of 70 to less than 85%.

[0061] Furthermore, for the polyester shrink film to be measured, it is preferable that the main shrinkage direction is the TD direction, and the heat shrinkage rate A2 when shrunk in the TD direction under the conditions of 80°C and 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 predetermined range, an even better heat shrinkage rate can be obtained in the polyester shrink film during heat shrinkage, and consequently, the maximum shrinkage stress can be more easily obtained. Therefore, as for configuration (a2), it is more preferable that the 80°C heat shrinkage rate A2 be in the range of 15 to less than 70%, and even more preferable that it be in the range of 20 to less than 50%.

[0062] Furthermore, 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 heat shrinkage rate A'2 when shrunk in the TD direction under the conditions of a temperature of 80°C and 10 seconds is within the range of 10 to less than 85%. The reason for this is that by setting the 80°C thermal shrinkage rate A'2 within a predetermined range, an even better thermal shrinkage rate can be obtained, and consequently, the maximum shrinkage stress can be more easily obtained. Therefore, it is more preferable that the 80°C heat shrinkage rate A'2 of the configuration (a'2) be in the range of 20 to less than 75%, and even more preferable that it be in the range of 30 to 65%.

[0063] (2) Configuration (b) Furthermore, it is preferable that the configuration (b) includes a requirement that B be the maximum shrinkage stress at a shrinkage temperature of 95°C in the TD direction of the polyester shrink film, and that B be a value within the range of 2 to 10 MPa. The reason for this is that by specifically limiting B to a value within a predetermined range, it is possible to suppress wrinkles that may occur due to an excess or deficiency of the maximum shrinkage stress. Therefore, for configuration (b), it is more preferable that the maximum shrinkage stress B at a shrinkage temperature of 95°C be within the range of 2.5 to 9.5 MPa, and even more preferable that it be within the range of 3 to 9 MPa.

[0064] (3) Composition (c) Furthermore, it is preferable that the configuration (c) has a configuration requirement such that the value expressed as B / A1, derived from the maximum shrinkage stress B and the thermal shrinkage rate A1, is within the range of 0.08 to 0.15 MPa / %. The reason for this is that by specifically limiting B / A1 to a value within a predetermined range, even if the values ​​of composition (a) and composition (b) vary somewhat, the influence of predetermined influencing factors can be reduced, thereby suppressing uneven shrinkage due to rapid thermal response in polyester shrink film during thermal shrinkage, and as a result, the occurrence of fine wrinkles can also be suppressed.

[0065] (4) Composition (d) Furthermore, it is preferable that the configuration (d) includes a requirement that the value represented by B / t, which is the ratio of the maximum shrinkage stress B in the polyester shrink film to its thickness t (μm), be within the range of 0.05 to 0.4 MPa / μm. The reason for this is that by specifically restricting B / t to a value within a predetermined range, it becomes easier to control the numerical value represented by B / A1 to a value within that predetermined range. Therefore, by reducing the factors of predetermined influencing elements, it is possible to suppress uneven shrinkage due to rapid thermal response in polyester shrink films during thermal shrinkage, and as a result, the occurrence of fine wrinkles can also be effectively suppressed.

[0066] (5) Composition (e) Furthermore, it is preferable that the configuration (e) includes a constituent requirement relating to the stretch ratio in the MD direction of the polyester shrink film before shrinkage (average MD direction stretch ratio, sometimes simply referred to as the MD direction stretch ratio). Furthermore, it is preferable that the MD-direction stretching ratio is within the range of 100 to 200%. The reason for this is that by specifically limiting the MD-direction stretching ratio to a value within a predetermined range, and by specifically limiting the predetermined thermal shrinkage rate, etc., to values ​​within a predetermined range, the occurrence of fine wrinkles can be further suppressed. Therefore, as configuration (e), it is more preferable to set the MD direction stretching ratio to a value in the range of 105 to 180%, and even more preferable to set it to a value in the range of 110 to 160%.

[0067] (6) Composition (f) Furthermore, it is preferable that the configuration (f) includes a component requirement relating to the stretch ratio in the TD direction of the polyester shrink film before heat shrinkage (average TD direction stretch ratio, sometimes simply referred to as the TD direction stretch ratio). Furthermore, it is preferable that the TD direction stretching ratio be within the range of 300 to 700%, more preferably within the range of 350 to 600%, and even more preferably within the range of 400 to 550%. The reason for this is that by specifically limiting the stretching ratio in the TD direction to a value within a predetermined range, and by specifically limiting the predetermined thermal shrinkage rate, etc., to values ​​within a predetermined range, the occurrence of fine wrinkles can be further suppressed.

[0068] (7) Composition (g) Furthermore, it is preferable that the composition (g) has a component requirement such that the haze value of the polyester shrink film before heat shrinkage, as measured in accordance with JIS K 7105, is 7% or less. The reason for this is that by specifically limiting the haze value to a predetermined range, the transparency of the polyester shrink film can be controlled quantitatively, and its versatility can be further enhanced due to its good transparency. More specifically, if the haze value of the film before heat shrinkage exceeds 7%, its transparency decreases, making it difficult to apply to decorative purposes on PET bottles, etc. On the other hand, if the haze value of the film before heat shrinkage becomes excessively small, it becomes difficult to control stably, which can lead to a significant decrease in production yield. Therefore, as configuration (g), it is more preferable that the haze value of the film before heat shrinkage be in the range of 0.1 to 5%, and even more preferable that it be in the range of 0.5 to 3%.

[0069] (8) Composition (h) Furthermore, composition (h) is a requirement that the polyester shrink film contains amorphous polyester resin in an amount of 90 to 100% by weight of the total amount. The reason for this is that by specifically limiting the content of amorphous polyester resin in this way, it becomes easier to adjust the thermal shrinkage rate and maximum shrinkage stress near the shrinkage temperature to a desired range, and it also becomes easier to control the haze value and other parameters with quantitative accuracy. More specifically, when the content of amorphous polyester resin falls below 90% by weight, it can become difficult to control the shrinkage rate and maximum shrinkage stress of the polyester shrink film near its shrinkage temperature. Furthermore, if the content of crystalline polyester resin becomes excessively high, the range in which the factors of the specified influencing elements are reduced may become significantly narrower. Therefore, as composition (h), it is more preferable that the content of amorphous polyester resin be in the range of 91 to 100% by weight of the total amount, and even more preferable that it be in the range of 92 to 100% by weight.

[0070] 4. Composition of polyester shrink film It is preferable to incorporate various additives into the polyester shrink film, or to attach them to one or both sides thereof. More specifically, it is preferable to blend at least one of the following—hydrolysis inhibitors, antistatic agents, ultraviolet absorbers, infrared absorbers, colorants, organic fillers, inorganic fillers, organic fibers, inorganic fibers, etc.—in an amount of typically 0.01 to 10% by weight relative to the total amount of polyester shrink film, and more preferably in an amount of 0.1 to 1% by weight.

[0071] Furthermore, as shown in Figure 1(b), it is also preferable to laminate other resin layers 10a, 10b containing at least one of these various additives onto one or both sides of the polyester shrink film 10. In that case, when the thickness of the polyester shrink film is set to 100%, it is preferable that the single-layer thickness or total thickness of the additionally laminated resin layers be within the range of 0.1 to 10%.

[0072] Furthermore, the resin that constitutes the other resin layers may be a polyester resin similar to that used in polyester shrink films, or it is preferable that it be at least one of the following: an acrylic resin, an olefin resin, a urethane resin, a rubber resin, etc.

[0073] Furthermore, it is preferable to create a multilayer structure for the polyester shrink film to further enhance hydrolysis prevention and mechanical protection, or, as shown in Figure 1(c), to provide a shrinkage rate adjustment layer 10c on the surface of the polyester shrink film 10 so that the shrinkage rate of the polyester shrink film becomes uniform across the surface. The shrinkage rate adjustment layer can be laminated using an adhesive, coating method, or heat treatment, depending on the shrinkage characteristics of the polyester shrink film.

[0074] More specifically, the thickness of the shrinkage rate adjustment layer is in the range of 0.1 to 3 μm, and it is preferable to laminate a shrinkage rate adjustment layer of a type that suppresses the shrinkage rate of the polyester shrink film at a predetermined temperature if the shrinkage rate is excessively large. Furthermore, if the shrinkage rate of the polyester shrink film at a predetermined temperature is excessively small, it is preferable to laminate a shrinkage rate adjustment layer of a type that expands the shrinkage rate. Therefore, instead of creating various shrink films with different shrinkage rates as polyester-based shrink films, the aim is to obtain the desired shrinkage rate by using a shrinkage rate adjustment layer.

[0075] 5. Measurement of other thermal properties (1) Thermal contraction rate Furthermore, when a polyester shrink film is heat-shrinked along the main shrinkage direction at a predetermined temperature T and a predetermined time t1, it is preferable to adjust the maximum value of the heat shrinkage rate calculated based on equation (2) to a predetermined range by utilizing a predetermined correlation between distance information of a predetermined section obtained by motion capture and the measurement time. In other words, as shown in Figure 6(a), PL0 is defined as the distance of a predetermined section measured by motion capture before thermal shrinkage, PL1 is defined as the distance of a predetermined section measured by motion capture at a predetermined time t2 which is shorter than the predetermined time t1, and it is preferable that the maximum value of the thermal shrinkage rate that can be calculated based on equation (2) be 3 mm / second or more.

[0076]

number

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

[0078] Here, we will refer to Figure 7 and explain the relationship between time (seconds) and the change in distance (mm) over a given section. Specifically, for Examples 1 and 2 and Comparative Examples 2 and 3 described later, time (seconds) was plotted on the horizontal axis, and the maximum value of the distance change (mm) in six predetermined sections set at a distance of 10 mm along the main contraction direction was plotted on the vertical axis. Measurements were taken at 0.1-second intervals and graphed. As can be seen from the graph, both Example 1 and Example 2 show a uniform increase between 0 and 2 seconds, and then continue to increase gradually thereafter. Furthermore, in Comparative Example 2, it can be seen that there is a portion between 0 and 1 second in which the change in distance over a predetermined interval decreases. On the other hand, in Comparative Example 3, it can be seen that the change in distance over the predetermined interval increases gradually between 0 and 1 second, rises sharply between 1 and 2 seconds, and then decreases slightly. Furthermore, it can be seen that in Comparative Example 3, the contraction rate at 1 second after the start of thermal contraction is approximately 1 / 3 to 1 / 2 of that of the other relational curves.

[0079] Furthermore, we will refer to Figures 8(a)-(b) and 9(a)-(b) to explain the relationship between time (seconds), thermal shrinkage rate (mm / second), and thermal shrinkage rate (% / second). Specifically, for Examples 1 and 2 and Comparative Examples 1 and 2 described later, time (seconds) was plotted on the horizontal axis, and the thermal shrinkage rate (mm / second) was plotted on the vertical axis at 0.1-second intervals for six predetermined sections set at 10 mm intervals along the main shrinkage direction, with the maximum value of the thermal shrinkage rate (mm / second) being the smallest. As shown in Figures 8(a) and 8(b), it can be seen that in both Example 1 and Example 2, the thermal shrinkage rate increases relatively steadily from immediately after the start of thermal shrinkage, exceeds 3 mm / second after about 1 second, and then decreases to 3 mm / second or less between 1 and 2 seconds. On the other hand, as can be seen from Figures 9(a) to 9(b), the thermal shrinkage rate of Comparative Example 2 and Comparative Example 3 does not increase significantly immediately after the start of thermal shrinkage, and does not exceed 3 mm / second even after 1 second has elapsed from the start of thermal shrinkage. In the cases shown in Figures 8(c) and 9(c), a thermal shrinkage rate of 1 mm / second corresponds to a thermal shrinkage rate of 10% / second.

[0080] (2) Thermal contraction rate Furthermore, as shown in Figure 6(a), it is preferable that the maximum value of the thermal shrinkage rate in the main shrinkage direction calculated based on the following formula (3) be 30% / second or more for the polyester shrink film.

[0081]

number

[0082] The reason for this is that by using such a thermal shrinkage rate, the balance between the amount of change and time at which the polyester shrink film changes most significantly can be precisely adjusted, effectively preventing wrinkles and other defects when the polyester shrink film is used on an object. Furthermore, by measuring the change in thermal shrinkage rate, it is possible to evaluate polyester shrink films regardless of the distance of a predetermined section. Therefore, it is more preferable to set the maximum thermal shrinkage rate to 3.5% / second or more, and even more preferable to set it to 4% / second or more.

[0083] (3) Standard deviation of the maximum thermal contraction rate Furthermore, for polyester shrink film, it is preferable to have multiple predetermined sections, and when the thermal shrinkage rate from the start of thermal shrinkage to a predetermined time t1 for each predetermined section is determined every 0.1 seconds, the standard deviation of the maximum thermal shrinkage rate for each predetermined section is 3.5 mm / second or less. The reason for this is that by using such a standard deviation, the rate of shrinkage over time during thermal contraction can be adjusted with greater precision, resulting in more stable behavior during thermal contraction. Therefore, it is more preferable to have a standard deviation of 1 mm / second or less for the maximum value of the thermal shrinkage rate, and even more preferable to have a standard deviation of 0.3 mm / second or less. The standard deviation is the square root of the value obtained by dividing the sum of the squares of the deviations by the number of data points minus 1.

[0084] (4) Thermal shrinkage rate during a specified period (intermediate thermal shrinkage rate) Furthermore, as shown in Figure 6(b), a predetermined section is provided along the main shrinkage direction of the polyester shrink film, which is in a state where it can be shrunk in at least one of the longitudinal or widthwise directions. When the film is heat-shrunk at a predetermined temperature T and a predetermined time t1, it is preferable that the heat shrinkage rate in the main shrinkage direction during a predetermined period (hereinafter sometimes referred to as the intermediate heat shrinkage rate) calculated based on the following formula (4) from 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 which is shorter than the predetermined time t1, and the distance PL2 of the predetermined section at a predetermined time t3 which is shorter than the predetermined time t1 and longer than the predetermined time t2, is 20 mm / second or less.

[0085]

number

[0086] The reason for this is that by using such an intermediate thermal shrinkage rate, it is possible to utilize a predetermined correlation between the distance change of a predetermined section of the polyester shrink film during thermal shrinkage and positional information obtained from motion capture, etc. Consequently, the thermal shrinkage rate of the polyester shrink film can be adjusted to a value within a predetermined range, allowing it to stably exhibit excellent thermal shrinkage properties. Therefore, it is more preferable to set the thermal shrinkage rate during the measurement period to 18 mm / second or less, and even more preferable to set it to 15 mm / second or less. The intermediate heat shrinkage rate is defined with the shrinkage direction of the polyester shrink film as positive, and a negative value is used when the polyester shrink film stretches due to the rebound effect of shrinkage, or when the film is distorted three-dimensionally due to rapid heat shrinkage and then returns to a flat state.

[0087] Furthermore, in the case of polyester shrink film, it is preferable that the measurement period t3-t2 be within 3 seconds. The reason for this is that by using such a measurement period, it is possible to measure the behavior during thermal contraction with greater 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 and other factors due to excessively increasing the temporal resolution, it is preferable to set the measurement period t3-t2 to a value of 0.1 seconds or more.

[0088] Furthermore, while it is preferable that the intermediate heat shrinkage rate is always a positive value during heat shrinkage, it has been found that even if it becomes a negative value, if the value is small, it does not pose a problem for the intended use of polyester shrink film. Therefore, it is preferable that the minimum intermediate heat shrinkage rate of the polyester shrink film during a predetermined period be kept to -2.5 mm / second or higher. In this way, by suppressing the behavior of polyester shrink film where the intermediate heat shrinkage rate becomes negative, wrinkles and other issues that occur when using polyester shrink film can be prevented more effectively. Therefore, it is more preferable to set the minimum intermediate thermal shrinkage rate to -1.5 mm / second or higher, and even more preferable to set it to 0 mm / second or higher.

[0089] Here, we will refer to Figures 10(a) to 13(a) and explain the relationship between time (seconds) and the intermediate thermal shrinkage rate (mm / second). Specifically, for Examples 1-2 and Comparative Examples 2-3 described later, time (seconds) was plotted on the horizontal axis, and the intermediate heat shrinkage rate (mm / second) was plotted on the vertical axis at 0.1-second intervals for six predetermined sections set at 10 mm intervals along the main shrinkage direction, with the maximum value of the intermediate heat shrinkage rate (mm / second) being the largest. As can be seen from Figures 10(a) to 11(a), in Example 1 and Example 2, the intermediate thermal shrinkage rate reaches its maximum value between 0 and 1 second, and decreases to approximately 0 mm / second after 1 second has elapsed from the start of thermal shrinkage. On the other hand, as shown in Figure 12(a), in Comparative Example 2, the intermediate thermal shrinkage rate reaches its maximum value between 0 and 1 second, but then between 1 and 2 seconds, it varies greatly around 0 mm / second. Furthermore, as shown in Figure 13(a), it can be seen that in Comparative Example 3, the intermediate thermal shrinkage rate was 5 mm / second or less between 0 and 1 second, increased to over 20 mm / second after about 1 second, and then decreased to 5 mm / second or less between 1.1 and 1.5 seconds. In the cases shown in Figures 10(b) to 13(b), a thermal shrinkage rate of 1 mm / second corresponds to a thermal shrinkage rate of 10% / second.

[0090] (5) Standard deviation of the maximum intermediate thermal contraction rate Furthermore, for polyester shrink film, it is preferable to have multiple predetermined sections, and when the thermal shrinkage rate from the start of thermal shrinkage to a predetermined time t1 for each predetermined section is determined every 0.1 seconds, the standard deviation of the maximum value of the intermediate thermal shrinkage rate for each predetermined section is 4.5 mm / second or less. The reason for this is that by using such a standard deviation, the shrinkage rate within a predetermined time during thermal shrinkage can be adjusted with greater precision, resulting in more stable behavior during thermal shrinkage. Therefore, it is more preferable to set the standard deviation of the maximum value of the intermediate thermal shrinkage rate to 3.5 mm / second or less, and even more preferable to set it to 3 mm / second or less. The standard deviation is the square root of the value obtained by dividing the sum of the squares of the deviations by the number of data points minus 1.

[0091] (6) Thermal shrinkage rate during a specified period (intermediate thermal shrinkage rate) Furthermore, as shown in Figure 6(b), when a polyester shrink film is heat-shrinked at a predetermined temperature T and a predetermined time t1, it is preferable that the intermediate heat shrink rate in the main shrink direction (hereinafter sometimes referred to as the intermediate heat shrink rate) calculated based on the change in distance between the distance PL0 of a predetermined section before heat shrinking, the distance PL1 of a predetermined section at a predetermined time t2 which is shorter than the predetermined time t1, and the distance PL2 of a predetermined section at a predetermined time t3 which is shorter than the predetermined time t1 and longer than the predetermined time t2, is 200% / second or less.

[0092]

number

[0093] The reason for this is that by using such an intermediate heat shrinkage rate, the heat shrinkage rate of the polyester shrink film can be adjusted with greater precision, regardless of the size of the polyester shrink film. Therefore, it is more preferable to set the intermediate thermal shrinkage rate to 180% / second or less, and even more preferable to set it to 150% / second or less.

[0094] On the other hand, from the viewpoint of preventing defects caused by excessively small shrinkage in a short period of time, it is preferable to set the intermediate heat shrinkage rate to 60% / second or more, more preferably to 80% / second or more, and even more preferably to 90% / second or more. Furthermore, while it is preferable that the intermediate thermal shrinkage rate always be a positive value, similar to the intermediate thermal shrinkage rate, it has been found that even if it becomes a negative value, if the value is small, it does not pose a problem for the intended use of polyester shrink film.

[0095] Therefore, it is preferable to keep the minimum intermediate heat shrinkage rate of polyester shrink films to -2.5% / second or higher. In this way, by suppressing the behavior of polyester shrink film where the intermediate heat shrinkage rate becomes negative, wrinkles and other issues that occur when using polyester shrink film can be prevented more effectively. Therefore, it is more preferable to set the minimum intermediate thermal shrinkage rate to -1.5% / second, and even more preferable to set it to 0% / second or higher.

[0096] Furthermore, when calculating the thermal shrinkage rate, it is preferable to set the predetermined times t2 and t3 to within 5 seconds. The reason for this is that by setting such a predetermined time, the behavior of 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 to 4 seconds or less, and even more preferable to set them to 3 seconds or less.

[0097] Furthermore, it is preferable that the time at which the intermediate thermal contraction rate is maximum is 1 second or less. The reason for this configuration is that it allows for control over the timing of the significant shrinkage of the polyester shrink film, enabling more precise adjustment of its thermal shrinkage characteristics. Therefore, it is more preferable to set the time at which the intermediate thermal shrinkage rate is maximum to 0.8 seconds or less, and even more preferable to set it to 0.6 seconds or less.

[0098] (7) Difference in thermal contraction rate every second Furthermore, when a polyester shrink film is heat-shrinked along the main shrink direction by providing a predetermined section along the main shrink direction of the polyester shrink film, and at a predetermined temperature T and a predetermined time t1, the distance of the predetermined section before heat shrinkage is defined as PL0, the distance of the predetermined section at a predetermined time t2 which is shorter than the predetermined time t1 is defined as PL1, the distance of the predetermined section at a predetermined time t3 which is shorter than the predetermined time t1 and longer than the predetermined time t2 is defined as PL2, and with a measurement period t3-t2 of 1 second, it is preferable that the difference in the heat shrink rate every second calculated based on the following formula (6) be 100% / second or less under predetermined conditions (predetermined temperature T: 70~98℃, predetermined time t1: more than 5 seconds).

[0099]

number

[0100] The reason for this is that by creating such a difference in thermal shrinkage rates, the polyester shrink film can be shrunk more stably. Therefore, it is more preferable to keep the difference in thermal shrinkage rate 80% / second or less, and even more preferable to keep it 50% / second or less.

[0101] [Second Embodiment] The second embodiment relates to a method for manufacturing the polyester shrink film of the first embodiment, using motion capture.

[0102] 1. Preparation and mixing of raw materials First, it is preferable to prepare main components and additives such as crystalline polyester resin, amorphous polyester resin, rubber-based resin, antistatic agents, and hydrolysis inhibitors as raw materials. Next, it is preferable to weigh the prepared crystalline polyester resin or amorphous polyester resin into the stirring container and mix and stir it using a stirring device until it becomes uniform.

[0103] 2. Process for creating the raw material sheet Next, it is preferable to dry the uniformly mixed raw materials to a completely dry state. Next, it is preferable to typically perform extrusion molding to create a raw material sheet of a predetermined thickness. More specifically, for example, by extruding the material at an extrusion temperature of 260°C using an extruder (manufactured by Tanabe Plastic Machinery Co., Ltd.) with an L / D ratio of 24 and an extrusion screw diameter of 50 mm, a raw material sheet of a predetermined thickness (usually 10 to 100 μm) can be obtained.

[0104] 3. Preparation of polyester shrink film Next, the obtained raw material sheet is heated and pressed using a shrink film manufacturing apparatus while moving it on and between rolls to create a polyester shrink film. In other words, it is preferable to crystallize the polyester molecules constituting the polyester shrink film into a predetermined shape by stretching it in a predetermined direction while heating and pressing it, while basically increasing the film width at a predetermined stretching temperature and stretching ratio. Then, by solidifying it in that state, a heat-shrinkable polyester shrink film can be created that can be used for decoration, labels, and the like.

[0105] 4. Measurement of thermal shrinkage rate using motion capture. Typically, it is preferable to measure the thermal shrinkage rate according to the following steps.

[0106] (1) The process of preparing a polyester shrink film as the object to be measured is carried out. In this case, it is preferable to confirm that the thickness of the polyester shrink film is within a predetermined range. Furthermore, it is preferable to measure the haze, glass transition temperature, and various thermal properties of the polyester shrink film in advance.

[0107] (2) Next, as shown in Figure 3(a), a step is taken to set two measurement positions (P1 and P2) in the TD direction, which is the main shrinkage direction of the polyester shrink film 10 before heat shrinking. Then, L1 is defined as the straight-line distance between the two measurement positions (P1 and P2) in the TD direction before heat shrinkage. Here, the two measurement positions (P1 and P2) in the TD direction are preferably located at a distance of 5 mm or more from the ends of the polyester shrink film, so that both ends are free when the planar shape of the polyester shrink film is rectangular or square.

[0108] Furthermore, as shown in Figure 3(a), it is preferable to perform a step of setting two additional measurement positions (P3 and P4) in the MD direction, which is perpendicular to the main contraction direction, in addition to the two measurement positions (P1 and P2) mentioned above. Furthermore, it is preferable that L2 be the linear distance between the two measurement positions (P3 and P4) in the MD direction before heat shrinkage. Here, the two measurement positions in the MD direction (P3 and P4) are preferably located at a distance of 5 mm or more from the edge, similar to the measurement positions in the TD direction, when the planar shape of the polyester shrink film is rectangular or square.

[0109] (3) Next, the polyester shrink film is subjected to a heat shrinking process. In other words, as shown in Figures 2(a) to (c), it is preferable to prepare a hot water bath 20 containing hot water 22 maintained at a predetermined temperature by a heater 22a, and to heat-shrink the polyester shrink film in the TD direction by immersing it in the hot water under conditions of a heat shrink temperature of 70 to 98°C and a shrink time of 1 to 60 seconds. In this case, as shown in Figure 2(b), it is preferable to prepare a mesh-like fixing jig 12 made of, for example, stainless steel wire, so that the polyester shrink film is uniformly immersed and heated, and to partially house the polyester shrink film 10 inside the jig. Furthermore, it is preferable that the fixing jig 12 is provided with openings 12' of a predetermined size corresponding to the measurement points P1 and P2, so that the polyester shrink film 10 does not stretch in the thickness direction and the shrinkage rate can be measured using motion capture or the like.

[0110] Furthermore, it is preferable that at least two linear objects 26 are attached to both ends of the polyester shrink film 10 via stainless steel fixing jigs 12 so that the polyester shrink film is uniformly immersed and heated for a predetermined time. In other words, it is preferable that these linear objects 26, such as wires, are further connected to a lifter 24, and that the lifter 24 can move up and down at a constant speed while maintaining the horizontal orientation of the polyester shrink film 10 by winding up and unwinding the linear objects 26.

[0111] Furthermore, in order to prevent the occurrence of temperature unevenness, it is preferable to heat-shrink the polyester shrink film 10 by immersing it in a hot water bath 20, as illustrated in Figure 2(b). On the other hand, from the viewpoint of measuring more quickly and simply, it is also preferable to heat-shrink the polyester shrink film 10 by floating it on the surface of hot water 22 maintained at a predetermined temperature in a hot water bath 20, as shown in Figures 2(a) and (c).

[0112] (4) Next, as shown in Figure 3(b), the distance between the two measurement positions (P1' and P2') in the TD direction of the heat-shrinkable polyester shrink film 10' is set as the second distance, and a measurement process using motion capture 14 is performed. In other words, as shown in Figures 3(b) and 14, it is preferable to prepare a predetermined motion capture device 14 and an inertial sensor 14', and use the motion capture device to measure the distance between two measurement positions in a polyester shrink film that has been heat-shrunk under predetermined conditions, with L'1 (sometimes referred to as the second distance). Furthermore, as shown in Figure 14, when cutting out measurement samples from three locations (W, C, E) along the TD direction to create multiple samples, it is preferable to attach predetermined markers to two measurement positions on each measurement sample (W, C, E) and then perform the measurements. On the other hand, it is also preferable to continuously measure the interval between two measurement points before or during the heat shrinkage of the polyester shrink film using motion capture or the like (for example, every 0.01 to 1 second).

[0113] Furthermore, the inertial sensor 14' shown in Figure 14 is preferably a combination of a long-axis sensor and several short-axis sensors that intersect it at 90° angles at equal intervals, with at least two measurement points provided at predetermined intervals at any given position. However, the inertial sensor 14' is not limited to these combinations, and it is also preferable that its planar shape be at least one of a circle, triangle, square, polygon, or irregular shape. In this example, inertial motion capture is used to measure the spacing between inertial sensors placed at predetermined intervals. However, it is also preferable to use image-based motion capture to measure predetermined markers such as oil-based markers.

[0114] Furthermore, as shown in Figure 3(b), it is preferable to perform the measurement process using motion capture with the distance between the two measurement positions (P3' and P4') in the MD direction as the second' distance. Then, L'2 is defined as the linear distance between the two measurement positions (P3' and P4') in the MD direction after thermal shrinkage. In other words, it is preferable to measure the 2' distance in the MD direction, similar to how the second distance in the TD direction is measured.

[0115] (5) Next, the process of calculating the thermal shrinkage rate in the TD direction based on equation (1) is carried out using L1, which is the distance between the two points before thermal shrinkage, and L'1, which is the distance between the two points after thermal shrinkage. Furthermore, it is preferable to confirm that the thermal shrinkage rate in the TD direction of the polyester shrink film is 20% or more.

[0116] Here, referring to Figure 15, we will explain the relationship between the immersion time and the thermal shrinkage rate (%) in the TD direction measured using motion capture, when the materials were immersed in 95°C hot water for 1 to 20 seconds, respectively, in Example 2 and Comparative Example 1. Specifically, the horizontal axis of Figure 15 shows the immersion time (seconds), and the vertical axis shows the thermal shrinkage rate (%) in the TD direction, measured using motion capture. In the case of the characteristic curve of Example 2 (line A), if the immersion time is approximately 1 second, the thermal shrinkage rate (%) obtained is almost the same as that obtained after 20 seconds. In contrast, in the case of the characteristic curve of Comparative Example 1 (line B), when comparing the thermal shrinkage rate (%) when the immersion time is 1 second with the thermal shrinkage rate when the immersion time is 20 seconds, a tendency is observed where the thermal shrinkage rate (%) increases as the immersion time increases. Therefore, it is preferable to determine the immersion time by considering the PET resin used, the thickness and thermal properties of the polyester shrink film obtained therefrom, and the manufacturing conditions.

[0117] Furthermore, referring to Figure 16, we will explain the relationship between the thickness (μm) of the 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. Specifically, the horizontal axis of Figure 16 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. Therefore, in the case of the characteristic curve (line C), it can be understood that the thicker the polyester shrink film (μm), the lower the thermal shrinkage rate (%), indicating a predetermined correlation (linear relationship). Therefore, it is preferable to adjust the thermal shrinkage rate (%) considering the thickness and thermal properties of the polyester shrink film.

[0118] Furthermore, it is preferable to perform a step to calculate the thermal shrinkage rate in the MD direction, similar to the thermal shrinkage rate in the TD direction, from L2, which is the distance between two points before thermal shrinkage, and L'2, which is the distance between two points after thermal shrinkage. Furthermore, it is preferable to confirm that the heat shrinkage rate in the MD direction of the polyester shrink film is within the range of -5 to 5%. The reason for this is that by simultaneously measuring the thermal shrinkage rate in the MD direction, it becomes easier to control the thermal shrinkage characteristics of the polyester shrink film when it is actually used, depending on the application of the polyester shrink film.

[0119] (6) Next, it is preferable to perform a step of comparing the obtained thermal shrinkage rate and thickness data with a calibration curve. In other words, it is preferable to confirm that the thickness of the polyester shrink film confirmed in step (1) and the value of the heat shrinkage rate obtained in step (5) match a pre-created calibration curve that shows the relationship between the thickness of the polyester shrink film and the heat shrinkage rate measured using motion capture.

[0120] (7) Next, it is also preferable to carry out a predetermined adjustment process. In other words, if the thermal shrinkage rate in the TD direction falls below 20%, it is preferable to reduce the thickness of the polyester shrink film, or to change the raw materials or manufacturing conditions of the polyester shrink film to adjust the thermal shrinkage rate to be within a predetermined range.

[0121] (8) Next, it is preferable to have a step of adjusting the standard deviation of the heat shrinkage rate as another predetermined adjustment step. 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 shrink film, or to change the raw materials or manufacturing conditions of the polyester shrink film so that the standard deviation of the thermal shrinkage rate falls within a predetermined range.

[0122] (9) Preferably, the next step involves calculating, by motion capture, other thermal shrinkage characteristics in the first embodiment, such as the thermal shrinkage rate, the standard deviation of the thermal shrinkage rate, the intermediate thermal shrinkage rate, the intermediate thermal shrinkage rate, and the difference in the intermediate thermal shrinkage rate every second. Furthermore, it is preferable to include a step of adjusting each measured value to within a predetermined range.

[0123] (10) Finally, it is also preferable to carry out other inspection processes. In other words, it is preferable to continuously or intermittently measure the following characteristics of the prepared polyester shrink film and to establish a predetermined inspection process. By measuring the following characteristics through the prescribed inspection process and confirming that they fall within a predetermined range, a polyester shrink film with more uniform shrinkage characteristics can be produced. 1) Visual inspection of the appearance of polyester shrink film 2) Measurement of thickness variation 3) Haze measurement 4) Measurement of the glass transition temperature 5) Measurement of melting point and heat of fusion 6) Measurement of tensile modulus 7) Measurement of tear strength 8) Measurement of viscoelastic properties using SS curves

[0124] [Third Embodiment] The third embodiment is an embodiment of a method for using a polyester shrink film having a heat shrinkage rate measured using motion capture. In other words, any known method of using shrink film can be suitably applied. For example, when using polyester shrink film, first, the polyester shrink film is cut to an appropriate length and width, and then a long cylindrical object is formed. Next, the long cylindrical object is supplied to an automatic labeling device (shrink labeler), cut to the required length, and then fitted onto a PET bottle or the like filled with its contents.

[0125] Next, the polyester shrink film fitted onto the PET bottle or the like is subjected to heat treatment by passing it through a hot air tunnel or steam tunnel at a predetermined temperature. Then, by using radiant heat such as infrared rays provided in these tunnels, and by blowing heated steam at around 90°C from the surroundings, the polyester shrink film is uniformly heated and thermally shrunk. Therefore, when the thermal shrinkage rate in the TD direction is 20% or more, a labeled container can be quickly obtained by adhering it tightly to the outer surface of a PET bottle or the like, as shown in Figures 17(a) to (d). On the other hand, if the thermal shrinkage rate in the TD direction falls below 20%, as shown in Figures 18(a) to (d), areas will appear from the top to the bottom of the bottle body where the label cannot conform to the shape of the bottle, and wrinkles will also be noticeably observed. [Examples]

[0126] 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 any particular reason. The polyester resins used in Example 1 and other examples are as follows:

[0127] (PETG1) A non-crystalline polyester (glass transition temperature: 69°C) consisting of dicarboxylic acid: 100 mol% terephthalic acid, diol: 69 mol% ethylene glycol, 20 mol% 1,4-cyclohexanedimethanol, and 11 mol% diethylene glycol.

[0128] (PETG2) A non-crystalline polyester consisting of dicarboxylic acid: 100 mol% terephthalic acid, diols: 63 mol% ethylene glycol, 24 mol% 1,4-cyclohexanedimethanol, and 13 mol% diethylene glycol (glass transition temperature: 69°C).

[0129] (PETG3) A non-crystalline polyester (glass transition temperature: 75°C) consisting of dicarboxylic acid: 100 mol% terephthalic acid, and diols: 68 mol% ethylene glycol, 30 mol% neopentyl glycol, and 2 mol% diethylene glycol.

[0130] (PETG4) A non-crystalline polyester (glass transition temperature: 69°C) consisting of dicarboxylic acid: 100 mol% terephthalic acid, diol: 70 mol% ethylene glycol, 28 mol% 1,4-cyclohexanedimethanol, and 2 mol% diethylene glycol.

[0131] [Example 1] 1. Preparation of polyester shrink film A amorphous polyester resin (PETG1) was used in a stirring vessel at a ratio of 100 parts by weight. Next, after the raw material was completely dried, it was extruded at an extrusion temperature of 260°C using an extruder (manufactured by Tanabe Plastic Machinery Co., Ltd.) with an L / D ratio of 24 and an extrusion screw diameter of 50 mm to obtain a raw material sheet with a thickness of 200 μm.

[0132] Next, using a shrink film manufacturing apparatus, a polyester shrink film with a thickness of 40 μm was prepared from a raw 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.

[0133] 2. Evaluation of polyester shrink film (1) Rating 1: Variation in thickness The thickness of the obtained polyester shrink film was measured using a micrometer (n=6) and evaluated according to the following criteria. ◎: The variation in thickness is within 3 μm. ○: The variation in thickness is within 5 μm. △: The variation in thickness is within 10 μm. ×: The variation in thickness exceeds 10 μm.

[0134] (2) Evaluation 2: Thermal shrinkage coefficient in the TD direction (A1) The resulting polyester shrink film was immersed in 95°C hot water for 1 second using a hot water bath to induce heat shrinkage. Next, as shown in Figure 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 distance of the markers before and after the heat treatment, obtained by the motion capture 14 image formula according to equation (1), and evaluated according to the following criteria. ◎: The thermal shrinkage rate (A1) is within the range of 50-85%. ○: The thermal shrinkage rate (A1) is between 30% and less than 50%, or between 85% and less than 90%. △: The thermal shrinkage rate (A1) is less than 20-30% or less than 90-95%. ×: The thermal shrinkage rate (A1) is less than 20% or greater than 95%.

[0135] (3) Evaluation 3: Standard deviation (σ1) of thermal shrinkage coefficient (A1) in the TD direction In Evaluation 2, the standard deviation (σ1) was calculated from the values ​​of thermal shrinkage coefficient (A1) in the TD direction (n=6) 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 thermal shrinkage rate (A1) is greater than 20%.

[0136] (4) Evaluation 4: Thermal contraction coefficient in the TD direction (A'1) The resulting polyester shrink film was immersed in 95°C hot water for 10 seconds using a hot water bath to induce heat shrinkage. Next, the dimensional changes before and after heat treatment were calculated from the data, and the thermal shrinkage rate (A'1) in the TD direction was calculated according to equation (1), and evaluated according to the following criteria. ◎: The thermal shrinkage rate (A'1) is within the range of 70-85%. ○: The thermal shrinkage rate (A'1) is between 65% and less than 70%, or between 85% and less than 90%. △: The thermal shrinkage rate (A'1) is between 60% and less than 65%, or between 90% and less than 95%. ×: The thermal shrinkage rate (A'1) is less than 60% or greater than 95%.

[0137] (5) Rating 5: Hayes The obtained polyester shrink film was measured for haze in accordance with JIS K 7105 and evaluated according to the following criteria. ◎: The haze level is 3% or less. ○: The haze level is 5% or less. △: Haze level is 7% or less. ×: The haze level is above 7%.

[0138] (6) Evaluation 6: Thermal shrinkage coefficient in the TD direction (A2) The resulting polyester shrink film was immersed in 80°C hot water for 1 second using a hot water bath to induce heat shrinkage. Next, as shown in Figure 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 marker distance before and after heat treatment obtained by the motion capture 14 image formula according to equation (1), and evaluated according to the following criteria. ◎: The thermal shrinkage rate (A2) is within the range of 20-50%. ○: Thermal shrinkage rate (A2) The percentage is between 15% and 20%, or between 50% and 70%. △: Thermal shrinkage rate (A2) The percentage is between 10% and 15%, or between 70% and 80%. ×: Thermal shrinkage rate (A2) The value is less than 10% or greater than 80%.

[0139] (7) Evaluation 7: Standard deviation (σ²) of thermal shrinkage coefficient (A²) in the TD direction In evaluation 6, the standard deviation (σ²) was calculated from the values ​​of thermal shrinkage coefficient (A²) in the TD direction (n=6) 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 thermal shrinkage rate (A2) is greater than 16%.

[0140] (8) Evaluation 8: Thermal contraction coefficient in the TD direction (A'2) The resulting polyester shrink film was immersed in 80°C hot water for 10 seconds using a hot water bath to induce heat shrinkage. Next, as shown in Figure 2(a), while capturing image data with an optical camera, the thermal shrinkage rate (A'2) in the TD direction was calculated from the change in marker distance before and after heat treatment obtained by the motion capture 14 image formula according to equation (1), and evaluated according to the following criteria. ◎: The thermal shrinkage rate (A'2) is within the range of 30-65%. ○: The thermal shrinkage rate (A'2) is less than 20-30% or less than 65-75%. △: The thermal shrinkage rate (A'2) is less than 10-20%, or less than 75-85%. ×: The thermal shrinkage rate (A'2) is less than 10% or greater than 85%.

[0141] (9) Evaluation 9: Standard deviation (σ'²) of thermal contraction coefficient (A'²) in the TD direction In evaluation 8, the standard deviation (σ'²) was calculated from the values ​​of the thermal shrinkage rate (A2') in the TD direction (n=6) obtained using image-based 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 greater than 10%.

[0142] (10) Rating 10: Thermal shrinkage rate 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 for more than 10 seconds using image-based motion capture. Specifically, while capturing image data with an optical camera, the thermal shrinkage rate in the main shrinkage direction was calculated according to equation (2) from the change in distance of a predetermined marker before and after a predetermined time obtained by image-based motion capture, and evaluated according to the following criteria. In calculating the thermal shrinkage rate, the distance PL0 of the predetermined section before thermal shrinkage was set to 10 mm, and measurements were taken at 0.1-second intervals. ◎: The thermal shrinkage rate is 4 mm / second or more. ○: The thermal shrinkage rate is 3 mm / second or more and less than 4 mm / second. △: The thermal shrinkage rate is 2 mm / second or more, and less than 3 mm / second. ×: The thermal shrinkage rate is less than 2 mm / second.

[0143] (11) Evaluation 11: Minimum intermediate thermal contraction rate The resulting polyester shrink film was heat-shrunk by floating it in 80°C hot water for 10 seconds using a hot water bath. Next, while capturing image data with an optical camera, the intermediate thermal shrinkage rate was determined according to equation (4) from the thermal shrinkage rate in the main shrinkage direction (number of predetermined intervals n=6) obtained by image-based motion capture, and the evaluation was performed according to the following criteria from the minimum value of the intermediate thermal shrinkage rate in the interval with the largest maximum intermediate thermal shrinkage rate among the predetermined intervals. In calculating the intermediate thermal shrinkage rate, the distance PL0 of the predetermined section before thermal shrinkage was set to 10 mm, and the measurement period t3-t2 was set to 0.1 seconds. ◎: The minimum value of the intermediate thermal shrinkage rate is 0 mm / second or greater. ○: The minimum intermediate thermal shrinkage rate is -1.5 mm / second or higher. △: The minimum intermediate thermal shrinkage rate is -2.5 mm / second or higher. ×: The minimum intermediate thermal shrinkage rate is less than -2.5 mm / second.

[0144] [Example 2] 1. Preparation of polyester shrink film In Example 2, as shown in Table 1, a raw sheet with a thickness of 200 μm was obtained in the same manner as in Example 1, except that 100 parts by weight of amorphous polyester resin (PETG2) was used in the stirring container. Next, using a shrink film manufacturing apparatus, a polyester shrink film with a thickness of 40 μm was prepared from a raw 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.

[0145] 2. Evaluation of polyester shrink film In Example 2, similar to Example 1, the variation in the thickness of the obtained polyester shrink film (Evaluation 1), the thermal shrinkage rate in the TD direction determined by image-based motion capture (Evaluation 2 and Evaluation 4), and the standard deviation of the thermal shrinkage rate in the TD direction determined by image-based motion capture (Evaluation 3) were measured and evaluated. The results are shown in Tables 2 and 3.

[0146] [Comparative Example 1] 1. Preparation of polyester shrink film In Comparative Example 1, as shown in Table 1, a raw sheet with a thickness of 200 μm was obtained in the same manner as in Example 1, except that 50 parts by weight of amorphous polyester resin (PETG3) and 50 parts by weight of amorphous polyester resin (PETG4) were used in the stirring container. Next, using a shrink film manufacturing apparatus, a polyester shrink film with a thickness of 40 μm was prepared from a raw 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.

[0147] 2. Evaluation of polyester shrink film In Comparative Example 1, the variation in the thickness of the obtained polyester shrink film (Evaluation 1), the thermal shrinkage rate in the TD direction determined by image-based motion capture (Evaluation 2 and Evaluation 4), and the standard deviation of the thermal shrinkage rate in the TD direction determined by image-based motion capture (Evaluation 3) were evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0148] [Comparative Example 2] 1. Preparation of polyester shrink film In Comparative Example 2, as shown in Table 1, a raw sheet with a thickness of 200 μm was obtained in the same manner as in Example 1, except that 100 parts by weight of amorphous polyester resin (PETG4) was used in the stirring vessel. Next, using a shrink film manufacturing apparatus, a polyester shrink film with a thickness of 40 μm was prepared from a raw 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.

[0149] 2. Evaluation of polyester shrink film In Comparative Example 2, the variation in the thickness of the obtained polyester shrink film (Evaluation 1), the thermal shrinkage rate in the TD direction determined by image-based motion capture (Evaluation 2 and Evaluation 4), and the standard deviation of the thermal shrinkage rate in the TD direction determined by image-based motion capture (Evaluation 3) were evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0150] [Comparative Example 3] 1. Preparation of polyester shrink film In Example 2, as shown in Table 1, a raw sheet with a thickness of 200 μm was obtained in the same manner as in Example 1, except that 100 parts by weight of amorphous polyester resin (PETG3) was used in the stirring vessel. Next, using a shrink film manufacturing apparatus, a polyester shrink film with a thickness of 40 μm was prepared from a raw 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.

[0151] 2. Evaluation of polyester shrink film In Comparative Example 3, similar to Example 1, the variation in the thickness of the obtained polyester shrink film (Evaluation 1), the thermal shrinkage rate in the TD direction by image-based motion capture (Evaluations 2 and 4), the standard deviation of the thermal shrinkage rate in the TD direction by image-based motion capture (Evaluation 3), etc. were evaluated. The results are shown in Tables 2 and 3.

[0152]

Table 1

[0153]

Table 2

[0154]

Table 3

Industrial Applicability

[0155] According to the present invention, by using motion capture and restricting at least the thermal shrinkage rate measured under predetermined conditions, etc. to values within a predetermined range, it has become possible to quickly and accurately evaluate and provide a polyester shrink film or the like that exhibits excellent wrinkle resistance characteristics. Therefore, according to the polyester shrink film of the present invention, it can be applied to various PET bottles and the like, and its versatility can be significantly expanded, and it can be said that its industrial applicability is extremely high.

Claims

1. A polyester shrink film having a predetermined heat shrinkage rate measured using motion capture, In the TD direction, which is the main shrinkage direction of the polyester shrink film to be measured, two measurement positions are set, and the distance between the two measurement positions is defined as L1. After the polyester shrink film has been heat-shrinked, the distance between the two measurement positions is defined as L'1, which is measured using the motion capture system. (1) The thermal shrinkage rate in the TD direction (temperature: 70 to 98°C, time: 1 to 60 seconds), calculated based on the following formula (1), shall be a value of 20% or more. (2) The thermal shrinkage rate A1 in the TD direction when shrinking under the conditions of a temperature of 95°C for 1 second shall be a value in the range of 40% to less than 90%. (2') The standard deviation of the thermal shrinkage rate A1 in the TD direction when shrinkage is performed at a temperature of 95°C for 1 second shall be 5% or less. (3) The thermal shrinkage rate A2 in the TD direction when shrinked at a temperature of 80°C for 1 second shall be a value within the range of 20% to less than 80%. (4) The thermal shrinkage rate measured using the motion capture device in a direction perpendicular to the main shrinkage direction of the polyester shrink film as the object to be measured, and measured simultaneously with the thermal shrinkage rate in the TD direction, shall be defined as the thermal shrinkage rate in the MD direction, and the thermal shrinkage rate in the MD direction shall be within the range of -5 to 5%. A polyester-based shrink film characterized by the following features. [Math 1]

2. The polyester shrink film according to claim 1, characterized in that the thickness of the polyester shrink film is in the range of 10 to 200 μm, and the difference between the maximum value of the thickness and the average value of the thickness is within 10 μm.

3. The polyester shrink film according to claim 1 or 2, characterized in that multiple measurement positions are set, and the average value of the thermal shrinkage rate in the TD direction obtained at these multiple positions is taken as the thermal shrinkage rate in the TD direction.

4. The polyester shrink film according to claim 1 or 2, characterized in that the motion capture is an image-type motion capture that detects information of a predetermined marker.

5. The polyester shrink film according to claim 1 or 2, characterized in that the motion capture system includes a camera for recording the thermal shrinkage state of the polyester shrink film.

6. The polyester shrink film according to claim 1 or 2, characterized in that the thermal shrinkage rate of the polyester shrink film is measured based on at least one thermal shrinkage device: a constant temperature bath, a steam bath, a hot water bath, a liquid bath of a fluorine-containing compound, a steam bath of a fluorine-containing compound, and an infrared irradiation device.

7. A calibration curve is prepared in advance showing the relationship between the heat shrinkage temperature and heat shrinkage time in the main shrinkage direction of the polyester shrink film as the object to be measured, and the heat shrinkage rate in the TD direction, and the calibration curve is compared and verified with the heat shrinkage rate obtained based on formula (1), and the heat shrinkage rate obtained based on formula (1) is set to a value within ±10% of the heat shrinkage rate in the TD direction obtained from the calibration curve, characterized in that the polyester shrink film according to claim 1 or 2.

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