Method for measuring heat shrinkage rate of polyester shrink film

Abstract

Provided is a method for measuring the thermal shrinkage rate of a polyester-based shrink film, said method being capable of measuring quickly and accurately using a motion capture instrument. A method for measuring the thermal shrinkage rate of a polyester-based shrink film using a motion capture device, said method comprising the following steps (a)-(e). Namely, the method comprises: a step (a) in which two measurement positions are set in the main contraction direction, and measurement is performed with the interval between the two measurement positions being L1; a step (b) for attaching a mark of the inertial measurement device to the measurement position; a step (c) for thermally shrinking the product by heating the product at a prescribed temperature and for a prescribed time, which are prescribed thermal shrinkage conditions; a step (d) in which the distance between the two measurement positions after thermal shrinkage is set as L '1 and measurement is performed using a motion capture instrument, and a step (e) in which the thermal shrinkage rate of the polyester-based shrink film is calculated on the basis of a prescribed formula.

Description

Technical Field

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

[0002] Shrink film has traditionally been widely used as a base film for labels on PET bottles and other products. Polyester resins are particularly popular due to their excellent transparency and strength. These shrink films are heat-shrunk by passing them through a tunnel generating hot air or steam before being attached to the container. However, heat shrinkage can cause differential (uneven) shrinkage, sometimes resulting in wrinkles and uneven color. Therefore, in order to prevent the occurrence of differential shrinkage (uneven shrinkage) during heat shrinkage, which in turn causes wrinkles and color unevenness, various heat-shrinkable polyester films have been proposed.

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

[0004] In addition, a heat-shrinkable polyester film has been proposed in which the amount of amorphous components in the full polyester resin composition is strictly controlled, and the hot water heat shrinkage rates at 80°C and 90°C in the longitudinal direction of the film and the hot water heat shrinkage rate at 90°C in the width direction of the film are limited (see Patent Document 2). More specifically, the film is a heat-shrinkable polyester film comprising ethylene terephthalate as a main component and containing one or more monomer components that can become amorphous components in the entire polyester resin component, the total amount of which is 15 mol % or more. Furthermore, the heat-shrinkable polyester film is characterized in that, in the longitudinal direction of the film, the hot water heat shrinkage rate of the polyester film is 30% or more when the treatment temperature is 80°C and the treatment time is 10 seconds, and is 40% or more when the treatment temperature is 90°C and the treatment time is 10 seconds, and the hot water shrinkage rate in the width direction of the film is 10% or less when the treatment temperature is 90°C and the treatment time is 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 a direction perpendicular to the direction are limited and the average heat shrinkage rate coefficient in the temperature range of 70 to 120° C. is set within a predetermined range (see Patent Document 3). More specifically, the film is a heat-shrinkable polyester film that is a homopolymer of polyethylene terephthalate or a copolymer containing a dicarboxylic acid component other than terephthalic acid and / or a diol component other than ethylene glycol and / or a hydroxycarboxylic acid. The heat-shrinkable polyester film is characterized in that the heat shrinkage rate in at least one direction is 30% or more, and the average heat shrinkage rate coefficient in at least the direction in the temperature range of 70 to 120° C. is in the range of 0.1 to 0.5% / sec·° C.

[0006] Furthermore, a shrink label has been proposed in which the maximum heat shrinkage rate measured under predetermined conditions is limited (see Patent Document 4). More specifically, the shrink label is a heat-shrinkable shrink label having at least one film layer containing a polylactic acid polymer as an essential component and a printing layer. The shrink label is characterized in that the heat shrinkage rate in the main orientation direction 1 second after the start of heat shrinkage in 75°C hot water is 3 to 23%, and the heat shrinkage rate in the main orientation direction under the conditions of 90°C for 10 seconds is 40 to 84%. Alternatively, the shrink label is characterized in that the maximum heat shrinkage rate in the main orientation direction in 75°C warm water is 7 to 40% / second, and the heat shrinkage rate in the main orientation direction under the conditions of 90°C for 10 seconds is 40 to 84%. Prior art literature Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 08-027259 (claims, etc.) Patent Document 2: Japanese Patent Application Laid-Open No. 2007-016120 (claims, etc.) Patent Document 3: Japanese Patent Application Laid-Open No. 8-323859 (claims, etc.) Patent Document 4: Japanese Patent Application Laid-Open No. 2008-1098 (claims, etc.) Summary of the Invention Technical Problems to be Solved by the Invention

[0008] However, although the heat shrinkage rate of the heat shrinkable films described in Patent Documents 1 and 2 is limited to a specified range at a specified temperature and in a specified shrinkage direction, after being immersed in warm water, it is necessary to remove the film from the warm water before measurement, which may easily cause uneven heat distribution and increase the deviation of the measured values. Therefore, it may be difficult to obtain a polyester film having a desired heat shrinkage rate from a polyester film having a heat shrinkage rate measured in this way, and it may be impossible to quickly and accurately manage the heat shrinkage rate characteristics. Therefore, especially in the case of PET bottles where the bottle body diameter is inconsistent and the horizontal cross-sectional shape of the bottle body has a complex shape depending on the location rather than a circle, the heat shrinkage tends to become uneven, so there is a problem that it is extremely difficult to suppress the generation of fine wrinkles.

[0009] Furthermore, although the heat shrinkage film described in Patent Document 3 limits the amount of change in heat shrinkage rate with respect to time, the limit is the averaged heat shrinkage rate coefficient (% / (second·°C)) before and after heat shrinkage, and does not consider measuring the heat shrinkage rate (mm / second) from before heat shrinkage to the specified time and its maximum value. Therefore, it is impossible to accurately measure the heat shrinkage rate (mm / second) at the timing when the heat shrinkage film changes significantly in a short period of time during heat shrinkage.

[0010] Furthermore, the shrink label described in Patent Document 4 defines the heat shrinkage rate (%) 1 second after the start of heat shrinkage. However, this is a heat shrinkage rate defined by time, and does not take into account the difference in heat shrinkage timing. In addition, although the maximum thermal shrinkage rate (% / second) is also described, the actual instantaneous thermal shrinkage rate when measured at intervals of 0.1 seconds is measured, and there is no consideration of measuring the maximum value of the thermal shrinkage rate (mm / second) from before thermal shrinkage to the specified time. Therefore, when converted into the maximum value of the heat shrinkage rate from before heat shrinkage to a predetermined time, a very small range is limited.

[0011] In response to this, the inventors of the present application discovered that by using a motion capture device to measure the thermal shrinkage rate in the main shrinkage direction and other directions through predetermined steps (a) to (e) and control the value, the thermal shrinkage characteristics can be measured quickly and accurately, thereby completing the present invention. That is, an object of the present invention is to provide a method for measuring the heat shrinkage rate of a polyester shrink film quickly and accurately using a predetermined motion capture device as a simple method. Technical means to solve technical problems

[0012] According to the present invention, a method for measuring the heat shrinkage of a polyester shrink film is provided, thereby solving the above-mentioned technical problems. The method is a method for measuring the heat shrinkage of a polyester shrink film using a motion capture device, characterized by comprising the following steps (a) to (e): Step (a): a step of setting two measurement positions in the main shrinkage direction of the polyester shrink film to be measured, and performing measurement with the interval between the two measurement positions being L1; Step (b): a step of setting predetermined marks at two measurement positions; Step (c): a step of heating the polyester shrink film at a predetermined temperature and for a predetermined time as predetermined heat shrinkage conditions to cause heat shrinkage; Step (d): a step of measuring the distance of the predetermined interval after heat shrinkage by setting it to L'1 using a motion capture device; Step (e): A step of calculating the heat shrinkage rate in the main shrinkage direction of the polyester shrinkage film based on the following formula (1), and setting the calculated heat shrinkage rate in the TD direction.

[0013] Thermal shrinkage in TD direction (%) = (L1-L'1) / L1×100(1)

[0014] That is, by measuring the thermal shrinkage rate at a predetermined position using a motion capture device after the predetermined steps (a) to (e), the thermal shrinkage rate with less variation can be measured quickly and accurately using a simple method.

[0015] When implementing the method for measuring the heat shrinkage of the polyester shrinkage film of the present invention, it is preferred to set the interval between the two measurement positions in the step (a) a plurality of times, calculate the heat shrinkage in the TD direction in the steps (d) to (e), and use the average value as the heat shrinkage in the TD direction. By calculating the thermal shrinkage in a plurality of TD directions in this manner, the thermal shrinkage rate in the TD direction can be measured more quickly and accurately.

[0016] When implementing the method for measuring the heat shrinkage of the polyester shrinkage film of the present invention, it is preferred that the motion capture device be an image-type motion capture device, and the heat shrinkage in the TD direction be calculated based on the positions of predetermined marks before and after heat shrinkage. By selecting and using an image-based motion capture device from among various types of motion capture devices, the position of a predetermined mark can be calculated efficiently, and the heat shrinkage rate can be measured quickly and accurately.

[0017] When carrying out the method for measuring the heat shrinkage rate of the polyester shrinkage film of the present invention, it is preferred to install a camera in advance in step (b) to simultaneously observe the heat shrinkage state of the polyester shrinkage film to be measured. By simultaneously recording the camera image in this manner, the state of heat shrinkage in the TD direction can be confirmed, and the heat shrinkage rate in the TD direction can be measured more quickly and accurately.

[0018] When carrying out the method for measuring the heat shrinkage of the polyester shrinkage film of the present invention, it is preferred that the heat shrinkage temperature in step (c) be 50 to 98° C. and the heat shrinkage time be 1 to 60 seconds. By setting such heat shrinkage conditions, it is possible to compare the heat shrinkage characteristics when the polyester shrinkage film is actually used.

[0019] When carrying out the method for measuring the heat shrinkage of the polyester shrinkage film of the present invention, the heat shrinking location in step (c) is preferably 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 setting such various heat shrinking locations, the heat shrinkage rate can be measured more quickly, accurately, and more simply according to the application of the polyester shrinkage film.

[0020] When implementing the method for measuring the heat shrinkage of a polyester shrinkage film of the present invention, in step (d), it is preferred that the heat shrinkage in a direction perpendicular to the main shrinkage direction of the polyester shrinkage film to be measured is defined as the heat shrinkage in the MD direction, and the heat shrinkage in the TD direction is measured simultaneously with the heat shrinkage in the MD direction using a motion capture device. By simultaneously measuring the heat shrinkage rate in the MD direction using a motion capture device in this manner, it is possible to compare the heat shrinkage characteristics of the polyester shrinkage film with those when the polyester shrinkage film is actually used, depending on the application of the polyester shrinkage film.

[0021] When implementing the method for measuring the heat shrinkage rate of the polyester shrinkage film of the present invention, it is preferred to include the following step as step (f) after step (e): a step of preparing in advance a calibration curve showing the relationship between the heat shrinkage temperature and heat shrinkage time in the main shrinkage direction of the polyester shrinkage film to be measured and the heat shrinkage rate in the TD direction, and comparing and verifying the calibration curve with the heat shrinkage rate obtained based on formula (1). By comparing and verifying with a previously prepared calibration curve in this manner, the thermal shrinkage rate can be measured more quickly, accurately, and reproducibly. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 (a) to (c) are diagrams for explaining the forms of polyester shrink films, respectively. Figure 2 (a) to (c) are diagrams for explaining a method for measuring the heat shrinkage rate of a polyester shrink film using a motion capture device or the like. Figure 3(a) to (b) are diagrams for explaining the positional shift of a predetermined mark due to heat shrinkage of a polyester shrink film. Figure 4 (a) to (b) are diagrams for explaining a method for measuring the heat shrinkage rate of a polyester shrink film using a motion capture device or the like. Figure 5 (a) to (c) are diagrams for explaining a configuration example of a fixing jig used for measuring a heat shrinkage rate using a motion capture device. Figure 6 (a) to (b) are diagrams for explaining the heat shrinkage rate and the heat shrinkage rate. Figure 7 This is a diagram for explaining the relationship between the change in distance (mm) in a predetermined section of the polyester shrink films of Examples 1 and 2 and Comparative Examples 2 and 3 and time (seconds). Figure 8 (a) to (b) are graphs for explaining the relationship between the heat shrinkage rate (mm / second) and time (second) of the polyester shrinkage films of Examples 1 and 2. Figure 8 (c) is a graph for explaining the relationship between the heat shrinkage rate (% / second) and time. Figure 9 (a) to (b) are graphs for explaining the relationship between the heat shrinkage rate (mm / second) and time (second) of the polyester shrinkage films of Comparative Examples 2 and 3. Figure 9 (c) is a graph for explaining the relationship between the heat shrinkage rate (% / second) and time. Figure 10 (a) is a graph for explaining the relationship between the intermediate heat shrinkage rate (mm / second) and time (second) of the polyester shrinkage film of Example 1. Figure 10 (b) is a graph for explaining the relationship between the intermediate thermal shrinkage rate (% / second) and time. Figure 11 (a) is a graph for explaining the relationship between the intermediate heat shrinkage rate (mm / second) and time (second) of the polyester shrinkage film of Example 2. Figure 11 (b) is a graph for explaining the relationship between the intermediate thermal shrinkage rate (% / second) and time. Figure 12 (a) is a graph for explaining the relationship between the intermediate heat shrinkage rate (mm / second) and time (second) of the polyester shrinkage film of Comparative Example 2. Figure 12 (b) is a graph for explaining the relationship between the intermediate thermal shrinkage rate (% / second) and time. Figure 13 (a) is a graph for explaining the relationship between the intermediate heat shrinkage rate (mm / second) and time (second) of the polyester shrinkage film of Comparative Example 3. Figure 13 (b) is a graph for explaining the relationship between the intermediate thermal shrinkage rate (% / second) and time. Figure 14 (a) is a diagram for explaining a plurality of measurement samples (W, C, E) collected from a roll-shaped polyester shrink film along the TD direction. Figure 14 (b) is a diagram for explaining a state where a motion capture device is installed on one of the measurement samples (W, C, E). Figure 15 This is a graph for explaining the relationship between the immersion time in 95°C warm water for 1 to 20 seconds and the heat shrinkage (%) in the TD direction measured using a motion capture device in Example 1 (line A) and Comparative Example 1 (line B). Figure 16 This is a graph for explaining the relationship between the thickness (μm) of a polyester shrinkage film when immersed in 95°C hot water for 20 seconds and the heat shrinkage rate (%) in the TD direction measured using a motion capture device. Figure 17 (a) is a diagram (photograph) showing the appearance of a tubular label when no wrinkles are generated, which corresponds to Example 1. Figure 17 (b) to (d) are respectively Figure 17 FIG. 1 is an enlarged view of the areas P, Q, and R of the appearance shown in (a). Figure 18 (a) is a diagram (photograph) showing the appearance of a tubular label corresponding to Comparative Example 1 when wrinkles are generated. Figure 18 (b) to (d) are respectively Figure 18 FIG. 1 is an enlarged view of the appearance areas S, T, and U shown in (a). DETAILED DESCRIPTION

[0023] [First embodiment] like Figure 1 The first embodiment is a method for measuring the heat shrinkage of a polyester shrink film using a motion capture device, characterized by comprising the following steps (a) to (e): Step (a): a step of setting two measurement positions in the main shrinkage direction of the polyester shrink film to be measured, and performing measurement with the interval between the two measurement positions being set to L1; Step (b): a step of setting predetermined marks at two measurement positions; Step (c): a step of heating the polyester shrink film at a temperature and for a time period specified as heat shrinkage conditions to cause heat shrinkage; Step (d): a step of setting the distance between the two measurement positions after heat shrinkage to L'1 and measuring using a motion capture device; Step (e): A step of calculating the heat shrinkage rate in the main shrinkage direction of the polyester shrinkage film based on the following formula (1).

[0024] Thermal shrinkage in TD direction (%) = (L1-L'1) / L1×100(1)

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

[0026] 1. Polyester shrink film (1) Polyester resin Basically, the type of polyester resin is not limited, but generally preferred are: polyester resin formed from diol and dicarboxylic acid; polyester resin formed from diol and hydroxycarboxylic acid; polyester resin formed from diol, dicarboxylic acid and hydroxycarboxylic acid; or a mixture of these polyester resins.

[0027] (2) Composition It is preferred that various additives are blended or attached to the polyester shrink film of the first embodiment, or to one or both surfaces thereof. More specifically, at least one of an anti-hydrolysis agent, an antistatic agent, an ultraviolet absorber, an infrared absorber, a colorant, an organic filler, an inorganic filler, an organic fiber, an inorganic fiber, etc. is preferably added in an amount of 0.01 to 10% by weight relative to the total weight of the polyester shrink film, and more preferably in an amount of 0.1 to 1% by weight.

[0028] In addition, if Figure 1 As shown in (b), it is also preferable to laminate other resin layers 10a and 10b containing at least one of the above-mentioned various additives on one or both surfaces of the polyester shrink film 10. In this case, when the thickness of the polyester shrink film is set to 100%, it is generally preferred that the thickness of each single layer or the total thickness of the other resin layers to be additionally laminated be within a range of 0.1 to 10%.

[0029] The main component of the other resin layer may be the same polyester resin as the polyester shrink film, or preferably at least one of acrylic resins, olefin resins, urethane resins, and rubber resins different from the polyester shrink film.

[0030] Furthermore, it is also preferred to make the polyester shrink film into a multilayer structure to further achieve anti-hydrolysis effect and mechanical protection; or Figure 1 As shown in (c), a shrinkage ratio adjusting layer 10c is provided on the surface of the polyester shrinkage film 10 so that the shrinkage ratio of the polyester shrinkage film becomes uniform within the surface. The shrinkage ratio adjusting layer can be laminated by adhesive, coating, heating, etc. according to the shrinkage characteristics of the polyester shrink film.

[0031] More specifically, the thickness of the shrinkage adjusting layer is in the range of 0.1 to 3 μm. When the shrinkage of the polyester shrinkage film at a predetermined temperature is excessively large, it is preferable to laminate a shrinkage adjusting layer of a type that suppresses the shrinkage. When the shrinkage rate of the polyester shrink film at a predetermined temperature is too small, it is preferable to laminate a shrinkage rate adjusting layer of a type that expands the shrinkage rate. Therefore, the polyester shrink film should obtain a desired shrinkage ratio by using a shrinkage ratio adjusting layer, rather than by producing various shrinkage films having different shrinkage ratios.

[0032] 2. Step (a) Step (a) is a step of preparing a polyester shrink film as a measurement object, setting two measurement positions in the main shrinkage direction thereof, and performing measurement with the interval between the two measurement positions being L1. Specifically, first, preferably, a crystalline polyester resin, a non-crystalline polyester resin, a rubber-based resin, an antistatic agent, an anti-hydrolysis agent, or other main ingredients or additives are prepared as raw materials. Next, the prepared crystalline polyester resin or non-crystalline polyester resin is preferably added into a stirring container while being weighed, and then mixed and stirred using a stirring device until uniform.

[0033] Next, the uniformly mixed raw materials are preferably dried to a completely dry state. Typically, extrusion molding is preferably performed to produce a raw sheet having a predetermined thickness. More specifically, for example, a raw material sheet of a predetermined thickness (usually 10 to 100 μm) can be obtained by extrusion molding at an extrusion temperature of 260° C. using an extruder having an L / D of 24 and an extrusion screw diameter of 50 mm (manufactured by TANABE PLASTICS MACHINERY CO., LTD.).

[0034] Next, the obtained raw material sheet is preferably heated and pressed while being moved on or between rolls using a shrink film production apparatus to produce a polyester shrink film. Specifically, it is preferred that the film width is substantially expanded at a predetermined stretching temperature and stretching ratio, and the film is simultaneously heated and pressed while being stretched in a predetermined direction, thereby allowing the polyester molecules constituting the polyester shrink film to crystallize into a predetermined shape. Then, by solidifying the film in this state, a heat-shrinkable polyester shrink film for use as a decoration or a label can be produced. In addition, it is preferable to measure the haze, glass transition temperature, or various thermal properties of the polyester shrinkage film in advance at this stage.

[0035] Then, if Figure 3 As shown in (a), it is preferable to implement a step of setting two measurement positions (P1 and P2) in the TD direction which is the main shrinkage direction of the polyester shrinkage film 10 before heat shrinkage. Furthermore, the interval between the linear distances of the two measurement positions (P1 and P2) in the TD direction before heat shrinkage is defined as L1.

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

[0037] When the planar shape of the polyester shrink film is a long strip (rectangular) or square, it is generally preferred to set the two measurement positions (P1 and P2) at positions 5 mm or more away from the ends to leave both ends free. At this time, it is preferable to confirm that the thickness of the polyester shrinkage film is a value within a predetermined range.

[0038] The measurement position is a portion indicating positional information of coordinates provided on the polyester shrink film in order to measure the behavior of the polyester shrink film during heat shrinkage. That is, Figure 4 As shown in (a) to (b) of FIG. 1 , a predetermined mark 15 such as a dot, a line, a cross mark, a circle mark, an arrow, an L-shape, a T-shape, or a check mark is preferably indicated as a predetermined interval M between two measurement positions. The reason for this is that by setting it as such a structure, it is possible to easily recognize that the polyester shrinkage film is shrinking from the periphery.

[0039] In addition, if Figure 3 As shown in (a), it is preferable to implement a step of setting two additional measurement positions (P3 and P4) different from the above two measurement positions (P1 and P2) in the MD direction which is a direction perpendicular to the main shrinkage direction. Furthermore, it is preferable that the interval between the linear distances of the two measurement positions (P3 and P4) in the MD direction before heat shrinkage is defined as L2. Here, when the planar shape of the polyester shrink film is a long strip (rectangular) or square, it is generally preferred to set two measurement positions (P3 and P4) in the MD direction at positions 5 mm or more from the ends, similar to the measurement positions in the TD direction.

[0040] 3. Step (b) like Figure 4 As shown in FIG. 1 , step (b) is a step of providing predetermined marks at two measurement positions ( P1 and P2 ) of the polyester shrink film. That is, when using an image-type motion capture device, it is preferable to introduce, for example, an oily marker, a metal wire, a groove, etc. as a predetermined mark, and to capture the position of the predetermined mark using an optical camera. Next, it is preferable to read the number of pixels from the captured moving image data, thereby obtaining the interval between the two measurement positions based on the relationship with the actual measurement. Therefore, by selecting and using an image-based motion capture device from among various types of motion capture devices, the position of a predetermined mark can be calculated efficiently, and the heat shrinkage rate can be measured quickly and accurately. On the other hand, when an inertial motion capture device is used, it is preferable to attach an inertial marker as a predetermined marker. That is, an IMU (the main part of a motion capture device) including an accelerometer, an angular velocity meter, etc. can more efficiently and accurately obtain acceleration information from an inertial marker, and can therefore more quickly and accurately measure the thermal shrinkage rate in the TD direction.

[0041] In addition, if Figure 14 As shown in FIG. 1 , when a plurality of measurement samples are cut from three positions (W, C, and E) along the TD direction, it is necessary to attach inertia marks to two measurement positions of each measurement sample. Then, if Figure 14 As shown, when the measurement sample is cut from three positions (W, C, E) along the TD direction to prepare a plurality of samples, it is preferable to set predetermined marks at two measurement positions of each measurement sample (W, C, E) and perform the measurement.

[0042] Here, Figure 4 The inertial sensor 14 ′ shown is a combination of a long-axis sensor and a plurality of short-axis sensors intersecting the long-axis sensor at 90° at equal intervals. Preferably, at least two measurement points are provided at predetermined intervals at arbitrary positions. However, the inertial sensor 14 ′ is not limited to the above combination forms, and preferably the planar shape is at least one of a circle, a triangle, a square, a polygon, or an irregular shape. Furthermore, it is preferable that at least two measurement points are formed of metal marks or printed materials such as paint containing a metal material so as to enable more rapid and accurate sensing.

[0043] 4. Step (c) The step (c) is a step of using a heat shrinking device to heat the polyester shrinkage film as the object to be measured at a predetermined temperature and for a predetermined time as heat shrinking conditions to cause heat shrinkage. Here, the heat shrinking device is preferably at least one of a constant temperature bath (oven), a steam bath, a warm water bath, a hot air heater, a fluorine-containing compound liquid bath, a fluorine-containing compound steam bath, and an infrared irradiation device. The reason for this is that when a motion capture device is used, various heat shrinkage devices can be used according to the application of the polyester shrink film, and the heat shrinkage rate can be measured more simply and accurately.

[0044] Furthermore, as an example, it is preferable that the heat shrinking device be a warm water bath. The reason for this is that by using such a heat shrinking device, the temperature of the hot water can be easily kept constant, and the heat shrinking temperature can be controlled more precisely. Furthermore, by using a warm water bath, the polyester shrink film can be floated and heated uniformly on a flat surface, and the behavior of the polyester shrink film during heat shrinkage can be more easily captured from above using an optical camera or the like.

[0045] Furthermore, as another example, it is preferable that the heat shrinking device is a hot air heater. That is, it is preferable to use a device that blows air supplied by a compressed air pump, a fan, or the like toward an object via a heat source such as an electric heating wire or an oil heater as the hot air heater. Specifically, for example, the heat shrinking device is preferably configured to heat shrink the polyester shrinkage film by blowing hot air from vertically above the polyester shrinkage film onto the polyester shrinkage film placed flat on a conveyor or a mounting table. The reason for this is that by using such a heat shrink device, the device has a higher degree of freedom in placement, can be placed above the polyester shrink film production device, and can blow hot air to the cut ends, etc., making it easier to measure the heat shrinkage rate online. Therefore, when using a hot air heater, the polyester shrink film is preferably placed in a tunnel-shaped housing made of stainless steel, aluminum, glass, or the like to receive the hot air from the perspective of efficiently transferring the heat of the hot air to the polyester shrink film.

[0046] Specifically, if Figure 2 As shown in (a) to (c), for example, it is preferred to prepare a warm water tank 20 containing hot water 22 maintained at a specified temperature by a heater 22a, and immerse the polyester shrink film in warm water under the conditions of heat shrinkage temperature: 70 to 98°C and shrinkage time: 1 to 60 seconds to heat shrink the polyester shrink film along the TD direction. At this time, if Figure 2 As shown in (b), it is preferred to prepare a mesh-shaped fixing jig 12 made of, for example, stainless steel wire so that the polyester shrink film is uniformly impregnated and heated, and to accommodate the polyester shrink film 10 in a portion of the interior thereof. Furthermore, it is preferable to adjust the polyester shrink film 10 so as not to stretch in the thickness direction and to enable shrinkage measurement using a motion capture device or the like. An opening 12 ′ of a predetermined size is provided in the fixing jig 12 , and the opening 12 ′ corresponds to positions corresponding to the measurement points P1 and P2 .

[0047] Furthermore, it is preferable that at least two thread-like objects 26 are attached to both end portions of the polyester shrink film 10 via the fixing jig 12 so that the polyester shrink film is further uniformly immersed and heated for a predetermined time. That is, it is preferable to set the following structure: the wire or the like as the above-mentioned linear object 26 is further connected to the elevator 24, and the elevator 24 winds or unwinds the linear object 26, while maintaining the horizontal direction of the polyester shrink film 10 and moving the polyester shrink film 10 up and down at a constant speed.

[0048] In addition, as a process for heat shrinking the polyester shrink film, from the perspective of preventing the occurrence of temperature unevenness, Figure 2 As exemplified in (b), the polyester shrink film 10 is preferably immersed in warm water in a warm water tank 20 to be heat-shrunk. On the other hand, from the perspective of faster and simpler measurement, Figure 2 As shown in (a) and (c) of FIG. 1 , it is also preferred that the polyester shrink film 10 be floated on the surface of hot water 22 maintained at a predetermined temperature in a hot water bath 20 to be heat-shrunk.

[0049] Furthermore, when heat shrinking the polyester shrink film, it is preferable to use a frame-shaped fixing jig that holds the posture of the polyester shrink film without hindering the shrinkage of the polyester shrink film. That is, Figure 5 As shown in (a) to (c), the fixing fixture 12 is composed of a frame component, and preferably has at least a loading portion 13a for loading and holding the polyester shrinkage film, a guide portion 13b for controlling the shrinkage direction of the polyester shrinkage film, and a limiting portion 13c for preventing displacement during heat shrinkage. Furthermore, from the perspective of further improving operability, the fixing jig 12 is preferably provided with at least a handle portion 13 d that is disposed at an end portion of the placement portion 13 a in the main contraction direction and that protrudes obliquely upward. Specifically, the fixing jig is preferably formed of a metal wire such as stainless steel, iron, aluminum, or copper, or a frame member such as a resin. The reason for this is that, with such a configuration, the polyester shrink film can be stably placed, shaking during heat shrinkage can be reduced, and the heat shrinkage rate can be measured with higher accuracy.

[0050] Furthermore, from the perspective of ease of handling and uniform heating of the polyester shrink film, the placement portion is a substantially flat frame-shaped portion, preferably two rail-shaped portions parallel to at least the main shrinking direction when viewed from above. Furthermore, the guide portion is preferably arranged parallel to the placement portion when viewed from above vertically, and is a portion that curves vertically in a wave-like manner. In addition, the limiting portion is configured in a manner that bridges the guide portion in a direction perpendicular to the main shrinkage direction, and is arranged so as to be movable upward and downward along the frame of the guide portion. It is a portion where the polyester shrinkage film loaded on the loading portion is clamped by the loading portion and the limiting portion. The reason for this is that, with such a configuration, the polyester shrink film can be prevented from being displaced during heat shrinkage, and the center position of shrinkage can be stabilized, thereby enabling the heat shrinkage rate to be accurately measured using a motion capture device. Furthermore, this is because, by bending the guide portion in a wave-like shape, for example, during heat shrinkage, when a warm water tank is used as a heat shrinking device, it can fall to the water surface without generating ripples, and by making the height of the guide portion consistent with the water level, measurement can be performed at the bottom of the water tank.

[0051] 5. Step (d) like Figure 3 As shown in (b), step (d) is a step of measuring the distance between two measurement positions (P1' and P2') in the TD direction of the heat-shrunk polyester shrink film 10' by setting the distance to a second distance. That is, Figure 3 (b) and Figure 14 As shown, a predetermined motion capture device 14 is prepared, and measurement is performed using the motion capture device 14 with the distance between two measurement positions in the TD direction of a polyester shrink film heat-shrunk under predetermined conditions being set to L′ 1 (also referred to as a second distance). On the other hand, it is also preferred to measure the distance between two measurement positions of the polyester shrink film before or during heat shrinkage by using a motion capture device or the like, continuously (for example, at time intervals of 0.01 to 1 second).

[0052] In addition, if Figure 3 As shown in (b), it is preferable to set the interval between the two measurement positions (P3' and P4') in the MD direction to the 2nd' distance and perform the measurement process using a motion capture device. Furthermore, the interval between the linear distances of the two measurement positions (P3' and P4') in the MD direction after heat shrinkage is defined as L'2. That is, similar to the measurement of the second distance in the TD direction, it is preferable to measure the 2nd' distance in the MD direction.

[0053] The intervals between the measurement positions of the polyester shrink film are preferably calculated based on positional information of the measurement positions obtained by a motion capture device. The reason for this is that by using such a motion capture device, the intervals between the measurement positions on the film can be acquired quickly and accurately in the form of digital data. Here, the motion capture device is a technology that converts the movement of a measurement object into digital data, and mainly tracks the position of a predetermined marker as a measurement object and records it as coordinate data.

[0054] Specifically, the type of motion capture device is not particularly limited, and there are image-based motion capture devices, inertial-based motion capture devices, optical-based motion capture devices, or a combination thereof. Any motion capture device can be used. However, in the case of polyester shrink films, since heat treatment is performed by immersion in warm water, etc., it is more preferable to use an image-type or inertial motion capture device because it is easy to miniaturize or simplify the device under conditions with many location restrictions.

[0055] Here, when a single motion capture device is used, the thermal shrinkage rate can be measured and calculated from two-dimensional measurement points, but when multiple motion capture devices are used, there is an advantage in being able to measure the positional relationship of three-dimensional measurement points and measure and calculate the thermal shrinkage rate based on this positional relationship. For example, when a flat heating plate is used as a heat shrink device, the heat shrinkage rate can be easily and quickly measured three-dimensionally even when it is tilted not only in the horizontal direction but also in the direction of gravity, or when it is arranged in the vertical direction so as to be parallel to the direction of gravity. Therefore, when using a single or multiple motion capture devices, various heat shrink devices can be used, and the heat shrinkage rate can be measured more quickly, accurately, and simply according to the application of the polyester shrink film.

[0056] More specifically, if Figure 2 As shown in (a), it is preferable to use an optical camera as an image-type motion capture device 14 to capture a moving image of the polyester shrinkage film 10 as the object to be measured during heat shrinkage, and perform image analysis on the acquired data to measure the heat shrinkage rate. That is, it is preferable that a plurality of scale marks (eg, 2 to 30 marks) are provided in advance on the polyester shrink film at predetermined intervals L1 using an oil-based marker or the like. Next, it is preferred that the polyester shrink film be placed on a flat surface and an optical camera be used to capture a moving image of the film before and after heat shrinkage from vertically above. Furthermore, it is preferable to calculate the intervals between each scale before heat shrinkage based on the relationship between the number of pixels and actual measurement based on the captured moving image data, and to use the average value thereof as the heat shrinkage ratio. Specifically, for example, when scales are arranged in the horizontal direction, it is preferable to draw a horizontal virtual line so as to intersect each scale, and use the point where the scale and the virtual line intersect as the measurement position. The reason for this is that by continuously recording the thermal shrinkage state in the form of moving image data, the thermal shrinkage rate in the TD direction can be measured more quickly, accurately, and efficiently. Furthermore, by performing recording in this manner, even when there are many limitations on the location, the device can be further miniaturized and simplified, and the thermal shrinkage rate can be measured more efficiently. The type of the predetermined mark may be any mark that is easily recognized by an optical camera, and is preferably composed of, for example, an oil-based mark, a groove, or the like.

[0057] In addition, the motion capture device is preferably an inertial position measurement device that can obtain acceleration, angular velocity, and orientation information obtained from an inertial sensor attached to a polyester shrink film using an IMU or other device, and accurately determine the position of the marker (center of gravity, etc.). Specifically, a combination of an accelerometer and an angular velocity meter (gyro sensor), or an inertial motion capture device including a 9-axis inertial sensor combining an accelerometer, an angular velocity meter, and a geomagnetometer is preferable.

[0058] On the other hand, an optical motion capture device is also preferably used as the motion capture device. That is, it is preferably an optical position measuring device of a type in which radiation such as infrared rays is irradiated from a motion capture device to an optical marker (such as a reflective marker) and reflected light is detected. The motion capture device is a measuring device capable of two-dimensionally determining the position (center of gravity, etc.) of a marker by performing predetermined image processing based on the obtained reflected light, and capable of determining a three-dimensional position by using a plurality of motion capture devices simultaneously.

[0059] In addition, if Figure 2 As shown in (b) to (c), it is preferred to use an inertial motion capture device 14 and specified optical cameras 14a and 14b at the same time to capture the heat shrinkage state of the polyester shrink film 10, convert it into image data to measure the heat shrinkage rate, and use it as a reference. The reason for this is that by continuously recording the thermal shrinkage state in conjunction with camera images, the thermal shrinkage state in the TD direction can be confirmed in the form of image data, and the thermal shrinkage rate in the TD direction can be measured more efficiently and accurately. More specifically, it is preferred to prepare a single or multiple optical cameras to capture image data of the heat-shrinkage state of the polyester shrinkage film as the object to be measured from the front, side, top, back, or oblique direction.

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

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

[0062] Here, refer to Figure 15 The relationship between the immersion time in 95° C. warm water and the heat shrinkage (%) in the TD direction measured using a motion capture device in Example 2 and Comparative Example 1 will be described. Right now, Figure 15 The horizontal axis represents the immersion time (seconds), and the vertical axis represents the heat shrinkage rate (%) in the TD direction measured using a motion capture device. In the case of the characteristic curve (line A) of Example 2, when the immersion time was about 1 second, a heat shrinkage rate (%) almost equivalent to the value after 20 seconds was obtained.

[0063] In contrast, in the case of the characteristic curve of Comparative Example 1 (line B), when the thermal shrinkage rate (%) when the immersion time is 1 second is compared with the thermal shrinkage rate when the immersion time is 20 seconds, a trend is obtained in which the thermal shrinkage rate (%) increases as the immersion time is longer. Therefore, it is preferable to set the immersion time in consideration of the PET resin used, the thickness and thermal properties of the polyester shrink film obtained from the PET resin, production conditions, and the like.

[0064] Further, refer to Figure 16The relationship between the thickness (μm) of a polyester shrink film when immersed in hot water at 95° C. for 20 seconds and the heat shrinkage rate (%) in the TD direction measured using a motion capture device will be described. Right now, Figure 16 The horizontal axis represents the thickness (μm) of the polyester shrinkage film, and the vertical axis represents the heat shrinkage rate (%) in the TD direction measured using a motion capture device.

[0065] Therefore, in the case of the characteristic curve (line C), the thicker the thickness (μm) of the polyester shrinkage film, the lower the heat shrinkage rate (%) can be obtained, and it is found that there is a predetermined correlation (linear relationship). Therefore, it is preferable to adjust the heat shrinkage ratio (%) in consideration of the thickness and thermal characteristics of the polyester shrinkage film.

[0066] 7. Process (f) It is preferable to provide step (f) to confirm that the obtained predetermined thermal shrinkage rate (temperature: 70 to 98° C., time: 1 to 60 seconds) is equal to or greater than a predetermined value (eg, 20% or greater) while comparing with a calibration curve. That is, it is preferable to confirm that the values ​​of the thickness and heat shrinkage rate of the polyester shrinkage film respectively agree with a previously prepared calibration curve showing the relationship between the thickness of the polyester shrinkage film and the heat shrinkage rate measured using a motion capture device. On the other hand, when the heat shrinkage is less than 20%, it is preferable to reduce the thickness of the polyester shrinkage film or change the raw material or production conditions of the polyester shrinkage film to adjust the heat shrinkage to within the specified range. Therefore, it is preferred to confirm that the specified thermal shrinkage rate (temperature: 70-98°C, time: 1-60 seconds) is a value of 30% or more and less than 95%, preferably a value within the range of 40% or more and less than 90%, and further preferably a value of 50% or more and less than 85%.

[0067] More specifically, it is preferred that the main shrinkage direction be the TD direction, and the heat shrinkage rate A1 in the TD direction when shrinking at 95° C. for 1 second be adjusted to a value within a range of 30% or more and less than 95%. The reason for this is that by limiting the 95° C. heat shrinkage ratio A1 to 30% or more and less than 95%, the polyester shrinkage film can obtain good wrinkle characteristics during heat shrinkage and can easily obtain the maximum shrinkage stress. Therefore, the 95°C heat shrinkage A1 is more preferably adjusted to a value within the range of 40% or more and less than 90%, and further preferably adjusted to a value within the range of 50% or more and less than 85%.

[0068] Furthermore, it is preferred that the main shrinkage direction be the TD direction, and the heat shrinkage rate A'1 in the TD direction when shrinking at 95°C for 10 seconds be adjusted to be within a range of 60% or more and less than 95%. The reason for this is that by limiting the 95° C. heat shrinkage ratio A′1 to 60% or more and less than 95%, the polyester shrinkage film can obtain good wrinkle characteristics during heat shrinkage and can easily obtain the maximum shrinkage stress. Therefore, the 95° C. heat shrinkage A′1 is more preferably adjusted to a value within the range of 65% or more and less than 90%, and further preferably adjusted to a value within the range of 70% or more and less than 85%.

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

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

[0071] In addition, similarly to the heat shrinkage in the TD direction, it is preferable to perform a step of calculating the heat shrinkage in the MD direction based on L2, which is the distance between two points before heat shrinkage, and L'2, which is the distance between two points after heat shrinkage, and adjusting the heat shrinkage in the MD direction. Furthermore, it is preferable to adjust the heat shrinkage rate in the MD direction of the polyester-based shrinkage film to a value within a range of -5 to 5%. The reason for this is that by simultaneously adjusting the heat shrinkage ratio in the MD direction, the heat shrinkage characteristics of the polyester shrinkage film when actually used can be more easily controlled according to the application of the polyester shrinkage film.

[0072] Furthermore, it is preferable to include a step of adjusting the standard deviation of the heat shrinkage ratio (temperature: 70 to 98° C., time: 1 to 60 seconds) as the predetermined adjustment step. More specifically, when calculating the heat shrinkage in the TD direction, it is preferred that the standard deviation (σ1) of the heat shrinkage in the TD direction under the conditions of a predetermined temperature and a predetermined time be adjusted to be within 15%. That is, when the standard deviation of the heat shrinkage in the TD direction exceeds 15%, it is preferable to reduce the thickness of the polyester shrinkage film or change the raw material or production conditions of the polyester shrinkage film to adjust the standard deviation of the heat shrinkage to within the specified range. The reason for this is that by adjusting the standard deviation of the heat shrinkage rate in this manner, the heat shrinkage rate of the polyester shrinkage film can be controlled with higher accuracy. Therefore, it is more preferable to adjust the standard deviation of the heat shrinkage rate in the TD direction to a value within 10%, and further preferably to a value within 5%.

[0073] Furthermore, it was found that the heat shrinkage rate measured using a motion capture device may be affected by the thickness of the polyester shrinkage film. Specifically, the thickness of the polyester shrink film is preferably set within a range of 10 to 200 μm, and the difference between the maximum thickness and the average thickness (hereinafter sometimes referred to as thickness variation) is adjusted to within 10 μm. The reason for this is that by controlling the thickness and thickness variation of the polyester shrinkage film, the heat shrinkage rate in the TD direction can be easily controlled, and the heat shrinkage rate in the TD direction can be controlled more quickly and accurately. However, if the thickness deviation is too small, the manufacturing yield will be extremely low, which may result in economic losses. Therefore, it is more preferable to adjust the thickness variation to a value within the range of 0.01 to 5 μm, and further preferably to a value within the range of 0.1 to 3 μm.

[0074] Furthermore, when measuring heat shrinkage using a motion capture device, the haze value of the polyester shrink film may affect image reading accuracy. That is, when measuring the heat shrinkage rate, the haze value of the polyester shrinkage film measured in accordance with JIS K7136:2000 is preferably adjusted to a value of 7% or less. On the other hand, if the haze value of the film before heat shrinkage is too small, it may be difficult to stably control it, and the production yield may be significantly reduced. Therefore, the haze value of the film before heat shrinkage is more preferably adjusted to a value within the range of 0.1 to 5%, and further preferably adjusted to a value within the range of 0.5 to 3%.

[0075] 8. Other thermal characteristics adjustment process (1) Thermal shrinkage speed Furthermore, as another step of adjusting thermal characteristics, it is preferable to include the following step of adjusting thermal characteristics such as heat shrinkage rate. Specifically, when the polyester shrink film is heat-shrunk along the main shrinkage direction at a specified temperature T and a specified time t1, it is preferred to adjust the maximum value of the heat shrinkage rate calculated based on the specified correlation between the distance information of the specified interval obtained by the motion capture device and the measurement time and the formula (2) to a specified range. That is, Figure 6 As shown in (a), it is preferred to set the maximum value of the heat shrinkage speed to be greater than 3 mm / s. The heat shrinkage speed can be calculated based on formula (2) by setting the distance of the specified interval measured by the motion capture device before heat shrinkage to PL0 and the distance of the specified interval measured by the motion capture device at a specified time t2 that is shorter than the specified time t1 to PL1.

[0076] Thermal shrinkage rate (mm / s) = (PL0-PL1) / t2(2) PL0-PL1: Distance change in the specified interval (mm) t2: Measurement period (seconds)

[0077] The reason for this is that by setting the maximum value of the heat shrinkage rate, the balance between the amount of change and time when the polyester shrinkage film undergoes the maximum change can be accurately adjusted, and the generation of wrinkles when the polyester shrinkage film is applied to an object can be effectively prevented. Therefore, the maximum value of the heat shrinkage rate is more preferably set to 3.5 mm / second or more, and further preferably set to 4 mm / second or more. In addition, it is preferable that the distance PL0 of the predetermined section before heat shrinkage is set to be the same as L1 or the like.

[0078] Here, refer to Figure 7 , the relationship between time (seconds) and distance change (mm) in a specified interval is explained. That is, for Examples 1 to 2 and Comparative Examples 2 to 3 described later, time (seconds) is set as the horizontal axis, and the maximum value of the distance change (mm) in the specified intervals set at 6 positions at a distance of 10 mm along the main shrinkage direction is set as the vertical axis, and measurements are taken at intervals of 0.1 seconds to produce a graph. As can be seen from the graph, the first and second embodiments both increase between 0 and 2 seconds, and continue to increase slowly thereafter. Furthermore, it can be seen that in Comparative Example 2, there is a portion where the distance change decreases in a predetermined interval between 0 and 1 second. On the other hand, it can be seen that the distance change in the predetermined section of Comparative Example 3 increases slowly between 0 and 1 second, rises sharply between 1 and 2 seconds, and then decreases slightly. Furthermore, it can be seen that the time of Comparative Example 3 at the point of 1 second after the start of thermal shrinkage is approximately 1 / 3 to 1 / 2 of that of the other relationship curves.

[0079] In addition, refer to Figure 8 (a)~(b) and Figure 9 (a) to (b) illustrate the relationship between time (seconds), thermal shrinkage rate (mm / second), and thermal shrinkage rate (% / second). Specifically, for Examples 1 to 2 and Comparative Examples 1 to 2 described later, time (seconds) is set as the horizontal axis, and the thermal shrinkage rate of the interval with the maximum value and the minimum thermal shrinkage rate (mm / second) in the specified intervals set at 6 positions at intervals of 10 mm along the main shrinkage direction is set as the vertical axis, and a graph is drawn at intervals of 0.1 seconds. According to the Figure 8 As can be seen from (a) to (b), the thermal shrinkage rate of Example 1 and Example 2 increases steadily shortly after the start of thermal shrinkage, exceeds 3 mm / second after 1 second, and decreases to below 3 mm / second between 1 and 2 seconds. On the other hand, according to Figure 9 As can be seen from (a) to (b), the heat shrinkage rates of Comparative Examples 2 and 3 did not increase much immediately after the start of heat shrinkage, and did not exceed 3 mm / s even after 1 second had passed from the start of heat shrinkage. In addition, in the Figure 8 (c) and Figure 9 In the case of (c), a heat shrinkage rate of 1 mm / sec corresponds to a heat shrinkage rate of 10% / sec.

[0080] (2) Thermal shrinkage rate In addition, if Figure 6 As shown in (a), the maximum value of the heat shrinkage rate in the main shrinkage direction of the polyester shrinkage film calculated based on the following formula (3) is preferably set to 30% / second or more.

[0081] Thermal shrinkage rate (% / second) = (PL0-PL1) / (PL0×t2)×100(3)

[0082] This is because by setting the heat shrinkage rate to such a level, the balance between the maximum change amount and time of the polyester shrinkage film can be accurately adjusted, and wrinkles can be effectively prevented when the polyester shrinkage film is applied to an object. Furthermore, this is because by measuring the amount of change associated with the heat shrinkage ratio, it is possible to evaluate the polyester shrinkage film without depending on the distance of the predetermined section. Therefore, the maximum value of the heat shrinkage rate is more preferably set to 3.5% / second or more, and further preferably set to 4% / second or more.

[0083] (3) Standard deviation of the maximum value of thermal shrinkage rate Furthermore, for a polyester shrink film, when a plurality of predetermined intervals are provided and the heat shrinkage rate from the time point of heat shrinkage initiation to a predetermined time t1 is calculated for each predetermined interval every 0.1 seconds, it is preferred that the standard deviation of the maximum value of the heat shrinkage rate in each predetermined interval be set to 3.5 mm / second or less. The reason for this is that by setting such a standard deviation, the shrinkage ratio at each time during heat shrinkage can be adjusted with high accuracy, and the behavior during heat shrinkage can be made more stable. Therefore, the standard deviation of the maximum value of the heat shrinkage rate is more preferably set to 1 mm / second or less, and further preferably set to 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 - 1.

[0084] (4) Thermal shrinkage rate during a specified period (intermediate thermal shrinkage rate) In addition, if Figure 6 As shown in (b), for the polyester shrinkage film, it is preferred that the heat shrinkage rate in the main shrinkage direction during a specified period (hereinafter sometimes referred to as the intermediate heat shrinkage rate) be set to 20 mm / s or less. The heat shrinkage rate is calculated based on the following formula (4) by setting a specified interval along the main shrinkage direction of the polyester shrinkage film in a state of being shrinkable in at least one of the longitudinal direction or the width direction, according to the distance change between the distance PL0 of the specified interval before heat shrinkage when heat shrinking at a specified temperature T and a specified time t1, the distance PL1 of the specified interval at a specified time t2 shorter than the specified time t1, and the distance PL2 of the specified interval at a specified time t3 shorter than the specified time t1 and longer than the specified time t2.

[0085] Intermediate thermal shrinkage speed (mm / s) = (PL1-PL2) / (t3-t2) (4) PL1-PL2: Distance change in the specified interval (mm) t3-t2: Measurement period (seconds)

[0086] The reason for this is that by setting such an intermediate heat shrinkage rate, it is possible to utilize a predetermined correlation between the change in distance within a predetermined section of the polyester shrinkage film during heat shrinkage and positional information obtained using a motion capture device, etc. Furthermore, the heat shrinkage rate of the polyester shrinkage film can be adjusted to a value within a predetermined range, thereby stably exhibiting excellent heat shrinkage properties. Therefore, the heat shrinkage rate during the measurement is more preferably set to 18 mm / second or less, and further preferably set to 15 mm / second or less. The intermediate heat shrinkage rate is positive in the shrinkage direction of the polyester shrinkage film and negative when the polyester shrinkage film is stretched by the reaction of shrinkage or when the film is three-dimensionally deformed by rapid heat shrinkage and then returns to a flat state.

[0087] In addition, for the polyester shrink film, it is preferable to set the measurement period t3 - t2 to a value within 3 seconds. The reason for this is that by setting such a measurement period, the behavior during heat shrinkage can be measured with higher accuracy. Therefore, the measurement period t3 - t2 is more preferably set to a value within 2 seconds, and further preferably set to a value within 1 second. On the other hand, from the perspective of preventing measurement errors and the like from increasing due to excessively increasing the time resolution, the measurement period t3 - t2 is preferably set to a value of 0.1 seconds or more.

[0088] Furthermore, it is preferred that the intermediate heat shrinkage rate always be a positive value during heat shrinkage. However, even when it is a negative value, it is known that there is no problem in terms of the intended use of the polyester shrinkage film if the value is small. Therefore, it is preferable to suppress the minimum value of the intermediate heat shrinkage rate of the polyester shrinkage film in a predetermined period to -2.5 mm / second or more. This is because wrinkles and the like can be more effectively prevented when the polyester shrinkage film is used as the polyester shrinkage film by suppressing the behavior of the intermediate heat shrinkage rate of the polyester shrinkage film becoming a negative value. Therefore, the minimum value of the intermediate heat shrinkage rate is more preferably set to -1.5 mm / sec or more, and further preferably set to 0 mm / sec or more.

[0089] Here, refer to Figure 10 (a)~ Figure 13 (a) of FIG. 1 illustrates the relationship between time (seconds) and intermediate heat shrinkage rate (mm / second). Specifically, for Examples 1 to 2 and Comparative Examples 2 to 3 described later, time (seconds) is set as the horizontal axis, and the intermediate heat shrinkage speed of the interval with the largest maximum value of the intermediate heat shrinkage speed (mm / second) in the specified intervals set at 6 positions at intervals of 10 mm along the main shrinkage direction is set as the vertical axis, and a graph is drawn at intervals of 0.1 seconds. According to the Figure 10 (a)~ Figure 11 As can be seen from (a), the intermediate heat shrinkage rate of Examples 1 and 2 reaches a maximum value between 0 and 1 second, and decreases to approximately 0 mm / second after 1 second from the start of heat shrinkage. On the other hand, according to Figure 12 As can be seen from (a), the intermediate heat shrinkage rate of Comparative Example 2 reaches a maximum value between 0 and 1 second, but then deviates significantly with 0 mm / second as the boundary between 1 and 2 seconds. Further, according to Figure 13 (a) shows that the intermediate heat shrinkage rate of Comparative Example 3 is less than 5 mm / second between 0 and 1 second. After about 1 second, the intermediate heat shrinkage rate increases to more than 20 mm / second, and then decreases to less than 5 mm / second between 1.1 and 1.5 seconds. In addition, in the Figure 10 (b)~ Figure 13 In the case of (b), a heat shrinkage rate of 1 mm / sec corresponds to a heat shrinkage rate of 10% / sec.

[0090] (5) Standard deviation of the maximum value of the intermediate thermal shrinkage rate Furthermore, for a polyester shrink film, when a plurality of predetermined intervals are provided and the heat shrinkage rate from the time point of the start of heat shrinkage to the predetermined time t1 is calculated for each predetermined interval every 0.1 second, it is preferred that the standard deviation of the maximum value of the intermediate heat shrinkage rate in each predetermined interval be set to 4.5 mm / second or less. The reason for this is that by setting such a standard deviation, the shrinkage ratio within a predetermined time during heat shrinkage can be adjusted with high accuracy, and the behavior during heat shrinkage can be made more stable. Therefore, the standard deviation of the maximum value of the intermediate heat shrinkage rate is more preferably set to 3.5 mm / second or less, and further preferably set 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 - 1.

[0091] (6) Thermal shrinkage rate during a specified period (intermediate thermal shrinkage rate) In addition, if Figure 6As shown in (b), for polyester shrinkage films, it is preferred that the intermediate heat shrinkage rate in the main shrinkage direction (hereinafter sometimes referred to as the intermediate heat shrinkage rate) be set to 200% / second or less, and the intermediate heat shrinkage rate is calculated based on the following formula (5) by changing the distance between the distance PL0 of the specified interval before heat shrinkage at the specified temperature T and the specified time t1, the distance PL1 of the specified interval at the specified time t2 which is shorter than the specified time t1, and the distance PL2 of the specified interval at the specified time t3 which is shorter than the specified time t1 and longer than the specified time t2.

[0092] Intermediate thermal shrinkage rate (% / s) =(PL1-PL2) / (PL0×(t3-t2))×100 (5)

[0093] The reason for this is that by setting the intermediate heat shrinkage rate to such an intermediate heat shrinkage rate, the heat shrinkage rate of the polyester shrinkage film can be adjusted with higher accuracy without depending on the size of the polyester shrinkage film. Therefore, the intermediate thermal shrinkage rate is more preferably set to 180% / second or less, and further preferably set to 150% / second or less.

[0094] On the other hand, from the perspective of preventing defects caused by excessive shrinkage in a short period of time, the intermediate thermal shrinkage rate is preferably set to 60% / second or more, more preferably 80% / second or more, and even more preferably 90% / second or more. In addition, similar to the intermediate heat shrinkage rate, the intermediate heat shrinkage rate is preferably always a positive value. However, even when it is a negative value, it is known that there is no problem in terms of the intended use of the polyester shrinkage film as long as the value is small.

[0095] Therefore, it is preferable to suppress the minimum value of the intermediate heat shrinkage rate of the polyester shrinkage film to -2.5% / second or more. This is because wrinkles and the like can be more effectively prevented when the polyester shrinkage film is used as the polyester shrinkage film by suppressing the behavior of the intermediate heat shrinkage rate of the polyester shrinkage film becoming a negative value. Therefore, the minimum value of the intermediate thermal shrinkage rate is more preferably set to -1.5% / second, and further preferably set to 0% / second or more.

[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 the predetermined time as described above, the behavior of the polyester shrinkage film during heat shrinkage can be measured in more detail. Therefore, it is more preferable to set the predetermined times t2 and t3 to within 4 seconds, and further preferably to within 3 seconds.

[0097] Furthermore, it is preferable that the time for the intermediate thermal shrinkage rate to reach the maximum be set to 1 second or less. The reason for this is that, with such a configuration, the timing at which the polyester shrinkage film significantly shrinks can be controlled, and the heat shrinkage characteristics can be adjusted with greater precision. Therefore, the time until the intermediate thermal shrinkage rate reaches the maximum is more preferably set to 0.8 seconds or less, and further preferably set to 0.6 seconds or less.

[0098] (7) Difference in thermal shrinkage rate per second In addition, for polyester shrinkage films, it is generally preferred to set the difference in heat shrinkage rate per second under specified conditions (specified temperature T: 70 to 98°C, specified time t1: greater than 5 seconds) to less than 100% / second. The heat shrinkage rate difference is calculated by setting a specified interval along the main shrinkage direction of the polyester shrinkage film, and when heat shrinking along the main shrinkage direction at a specified temperature T and a specified time t1, setting the distance of the specified interval before heat shrinkage to PL0, setting the distance of the specified interval at a specified time t2 that is shorter than the specified time t1 to PL1, and setting the distance of the specified interval at a specified time t3 that is shorter than the specified time t1 and longer than the specified time t2 to PL2, setting the measurement period t3-t2 to 1 second, and calculating based on the following formula (6).

[0099] Difference in thermal shrinkage rate per second (% / second) =(PL0-PL1) / (PL0×t2)×100 -(PL0-PL2) / (PL0×t3)×100(6)

[0100] The reason for this is that by setting such a difference in the heat shrinkage rate, the polyester shrinkage film can be shrunk more stably. Therefore, the difference in the heat shrinkage rate is more preferably set to 80% / second or less, and further preferably set to 50% / second or less.

[0101] 9. Other inspection processes That is, it is preferred to continuously or intermittently measure the following properties and the like for the produced polyester shrink film, and to provide a predetermined inspection step. That is, by measuring the following properties and the like through a predetermined inspection process and confirming that the values ​​fall within a predetermined range, a polyester shrink film having more uniform shrinkage properties and the like can be produced. 1) Visual inspection of the appearance of polyester shrink film 2) Thickness deviation measurement 3) Determination of tensile elastic modulus 4) Tear strength measurement 5) Determination of viscoelastic properties based on SS curve 6) Thermal properties (TD direction, MD direction) 7) Thermal shrinkage stress 8) Stretch ratio

[0102] [Second embodiment] The second embodiment relates to a method for using a polyester shrink film whose heat shrinkage rate is measured using a motion capture device. Therefore, any known method of using a shrink film can be appropriately applied. For example, when implementing the method of using a polyester shrink film, first, the polyester shrink film is cut into a suitable length or width to form a long tube. Next, the long tube is fed to an automatic label attaching device (shrink labeler) and further cut into a desired length. Next, it is externally fitted on a PET bottle or the like filled with the content.

[0103] Next, as a heat treatment for the polyester shrink film after being externally fitted on a PET bottle or the like, the film is passed through a hot air tunnel or a steam tunnel at a predetermined temperature. Then, radiant heat such as infrared rays or heating steam at about 90° C. provided in the tunnel is blown from the surroundings to uniformly heat and heat-shrink the polyester shrink film.

[0104] Therefore, when the heat shrinkage in the TD direction is more than 20%, Figure 17 As shown in (a) to (d), it can be closely attached to the outer surface of a PET bottle or the like, and a labeled container can be quickly obtained. On the other hand, when the heat shrinkage in the TD direction is less than 20%, as Figure 18 As shown in (a) to (d), regions where the label cannot follow the shape of the bottle periphery are generated from the upper part to the lower part of the bottle body, and wrinkles are also significantly observed. Example

[0105] The present invention will be described in detail below based on the following examples. However, unless there is a special reason, the scope of the present invention is not limited by the description of the examples. In addition, the polyester resin used in Example 1 and the like is as follows.

[0106] (PETG1) A non-crystalline polyester (glass transition temperature: 69°C) composed of 100 mol% of terephthalic acid (dicarboxylic acid), 69 mol% of ethylene glycol (diol), 20 mol% of 1,4-cyclohexanedimethanol, and 11 mol% of diethylene glycol.

[0107] (PETG2) A non-crystalline polyester (glass transition temperature: 69°C) composed of 100 mol% of terephthalic acid (a dicarboxylic acid), 63 mol% of ethylene glycol (a diol), 24 mol% of 1,4-cyclohexanedimethanol, and 13 mol% of diethylene glycol.

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

[0109] (PETG4) A non-crystalline polyester (glass transition temperature: 69°C) composed of 100 mol% of terephthalic acid (a dicarboxylic acid), 70 mol% of ethylene glycol (a diol), 28 mol% of 1,4-cyclohexanedimethanol, and 2 mol% of diethylene glycol.

[0110] [Example 1] 1. Production of polyester shrink film A non-crystalline polyester resin (PETG1) was used in a stirring container at a ratio of 100 parts by weight. The raw material was completely dried and then extruded at an extrusion temperature of 260°C using an extruder (manufactured by TANABE PLASTICS MACHINERY CO., LTD.) with an L / D of 24 and an extrusion screw diameter of 50 mm to obtain a raw material sheet with a thickness of 200 μm.

[0111] Next, using a shrink film manufacturing apparatus, a polyester shrink film with a thickness of 40 μm was produced from the raw material sheet under the conditions of a preheating temperature of 75°C, a stretching temperature of 75°C, a stretch ratio (MD direction: 105%, TD direction: 500%), and a heat setting temperature of 60°C.

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

[0113] (2) Evaluation 2: Thermal shrinkage in the TD direction (A1) The obtained polyester shrinkage film was immersed in 95° C. warm water for 1 second using a warm water bath to cause heat shrinkage. Then, if Figure 2 As shown in (a), while capturing image data with an optical camera, the heat shrinkage rate (A1) in the TD direction is calculated according to the change in the distance of the mark before and after the heating treatment obtained by the image-type motion capture device 14 according to formula (1), and evaluated according to the following standards. ⊚: The thermal shrinkage ratio (A1) is a value within the range of 50% or more and less than 85%. ○: The thermal shrinkage (A1) is a value of 30% or more and less than 50% or 85% or more and less than 90%. Δ: The thermal shrinkage ratio (A1) is a value of 20% or more and less than 30% or 90% or more and less than 95%. ×: The heat shrinkage ratio (A1) is a value less than 20% or greater than 95%.

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

[0115] (4) Evaluation 4: Thermal shrinkage in TD direction (A'1) The obtained polyester shrinkage film was immersed in 95° C. warm water for 10 seconds using a warm water bath to cause heat shrinkage. Next, the dimensional changes before and after the heat treatment were calculated in the form of data, the thermal shrinkage (A'1) in the TD direction was calculated according to formula (1), and the evaluation was performed according to the following criteria. ⊚: The thermal shrinkage ratio (A'1) is a value within the range of 70 to 85%. ○: The thermal shrinkage (A'1) is a value of 65% or more and less than 70% or 85% or more and less than 90%. Δ: The thermal shrinkage ratio (A'1) is a value of 60% or more and less than 65% or a value of 90% or more and less than 95%. ×: The thermal shrinkage ratio (A'1) is a value less than 60% or greater than 95%.

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

[0117] (6) Evaluation 6: Thermal shrinkage in TD direction (A2) The obtained polyester shrinkage film was immersed in 80° C. warm water using a warm water bath for 1 second to be heat-shrunk. Then, if Figure 2 As shown in (a), while capturing image data with an optical camera, the heat shrinkage rate (A2) in the TD direction is calculated according to the change in the distance of the mark before and after the heating treatment obtained by the image-type motion capture device 14 according to formula (1), and evaluated according to the following standards. ⊚: The thermal shrinkage ratio (A2) is a value within the range of 20% or more and less than 50%. ○: The thermal shrinkage (A2) is a value of 15% or more and less than 20% or 50% or more and less than 70%. Δ: The heat shrinkage ratio (A2) is a value of 10% or more and less than 15% or 70% or more and less than 80%. ×: The heat shrinkage ratio (A2) is a value less than 10% or greater than 80%.

[0118] (7) Evaluation 7: Standard deviation (σ2) of thermal shrinkage (A2) in the TD direction The standard deviation (σ2) was calculated from the values ​​(n=6) of the heat shrinkage rate (A2) in the TD direction obtained using an image-type motion capture device in Evaluation 6, and evaluation was performed according to the following criteria. ⊚: The standard deviation of the thermal shrinkage ratio (A2) is within 4%. ○: The standard deviation of the thermal shrinkage ratio (A2) is within 8%. Δ: The standard deviation of the thermal shrinkage ratio (A2) is within 12%. ×: The standard deviation of the thermal shrinkage ratio (A2) is larger than 16%.

[0119] (8) Evaluation 8: Thermal shrinkage in TD direction (A'2) The obtained polyester shrinkage film was immersed in 80° C. warm water for 10 seconds using a warm water bath to cause heat shrinkage. Then, if Figure 2As shown in (a), while capturing image data with an optical camera, the heat shrinkage rate (A'2) in the TD direction was calculated based on the change in the distance between the marks before and after the heating treatment obtained by the image-based motion capture device 14 according to formula (1), and evaluated according to the following criteria. ⊚: The thermal shrinkage ratio (A'2) is a value within the range of 30% or more and less than 65%. ○: The thermal shrinkage (A'2) is a value of 20% or more and less than 30% or 65% or more and less than 75%. Δ: The thermal shrinkage ratio (A'2) is a value of 10% or more and less than 20% or 75% or more and less than 85%. ×: The thermal shrinkage ratio (A'2) is a value less than 10% or greater than 85%.

[0120] (9) Evaluation 9: Standard deviation (σ'2) of thermal shrinkage in the TD direction (A'2) The standard deviation (σ'2) was calculated from the values ​​(n=6) of the heat shrinkage rate (A'2) in the TD direction obtained using an image-type motion capture device in Evaluation 8, and evaluation was performed according to the following criteria. ⊚: The standard deviation of the thermal shrinkage ratio (A'2) is within 2.5%. ○: The standard deviation of the thermal shrinkage (A'2) is within 5%. Δ: The standard deviation of the thermal shrinkage ratio (A'2) is within 7.5%. ×: The standard deviation of the thermal shrinkage ratio (A'2) is larger than 10%.

[0121] (10) Evaluation 10: Thermal Shrinkage Rate The obtained polyester shrink film was floated in 80° C. warm water using a warm water bath for 10 seconds, and heat-shrunk while being measured for 10 seconds or longer using an image-type motion capture device. Specifically, while capturing image data with an optical camera, the heat shrinkage rate in the main shrinkage direction was calculated according to equation (2) based on the change in distance between predetermined marks before and after a predetermined time obtained with an image-based motion capture device, and evaluated according to the following criteria. At this time, when calculating the heat shrinkage rate, the distance PL0 of the predetermined section before heat shrinkage was set to 10 mm, and the measurement was performed at intervals of 0.1 seconds. ◎: The heat shrinkage rate is 4 mm / s or more. ○: The heat shrinkage rate is 3 mm / s or more and less than 4 mm / s. △: The heat shrinkage rate is 2 mm / second or more and less than 3 mm / second. ×: The heat shrinkage rate is less than 2 mm / second.

[0122] (11) Evaluation 11: Minimum value of intermediate thermal shrinkage rate The obtained polyester shrinkage film was floated in 80° C. warm water using a warm water bath for 10 seconds to cause heat shrinkage. Next, while capturing image data using an optical camera, the intermediate thermal shrinkage rate is calculated according to formula (4) based on the thermal shrinkage rate in the main shrinkage direction obtained using an image-based motion capture device (the number of specified intervals n = 6), and the evaluation is performed according to the following standards based on the minimum value of the intermediate thermal shrinkage rate in the interval with the largest maximum value of the intermediate thermal shrinkage rate in the specified interval. At this time, when calculating the intermediate heat shrinkage rate, the distance PL0 of the predetermined section before heat shrinkage was set to 10 mm and the measurement period t3 - t2 was set to 0.1 seconds. ◎: The minimum value of the intermediate heat shrinkage rate is 0 mm / s or more. ○: The minimum value of the intermediate heat shrinkage rate is -1.5 mm / s or more. △: The minimum value of the intermediate heat shrinkage rate is -2.5 mm / sec or more. ×: The minimum value of the intermediate heat shrinkage speed is less than -2.5 mm / sec.

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

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

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

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

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

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

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

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

[0131] [Table 1]

[0132] [Table 2] Evaluation 1 Evaluation 2 Rating 3 Rating 4 Rating 5 Example 1 ◎ ◎ ◎ ◎ ◎ Example 2 ○ ◎ ◎ ◎ ○ Comparative Example 1 × × ○ △ ◎ Comparative Example 2 × × ○ △ ◎ Comparative Example 3 △ × ◎ ○ ◎ Evaluation 1: Thickness variation, Evaluation 2: A1, Evaluation 3: σ1, Evaluation 4: A'1, Evaluation 5: Haze

[0133] [Table 3] Rating 6 Rating 7 Rating 8 Rating 9 Rating 10 Rating 11 Example 1 ◎ ◎ ◎ ◎ ◎ ○ Example 2 ◎ ◎ ◎ ◎ ○ ○ Comparative Example 1 ◎ ○ ◎ ◎ △ △ Comparative Example 2 ◎ ○ ◎ ◎ △ △ Comparative Example 3 × △ ◎ ◎ × × Evaluation 6: A2, Evaluation 7: σ2, Evaluation 8: A'2, Evaluation 9: σ'2, Evaluation 10: Heat shrinkage rate, Evaluation 11: Minimum value of the intermediate heat shrinkage rate Industrial Applicability

[0134] According to the present invention, by using a motion capture device and limiting at least the heat shrinkage rate measured under predetermined conditions to a value within a predetermined range, a polyester shrink film or the like exhibiting excellent wrinkle resistance can be rapidly and accurately evaluated and provided. Therefore, the polyester shrink film according to the present invention can be applied to various PET bottles and the like, can significantly broaden its versatility, and has extremely high industrial applicability.

Claims

1. A method for measuring the heat shrinkage of a polyester shrink film, wherein the method uses a motion capture device to measure the heat shrinkage of the polyester shrink film in its main shrinkage direction, characterized in that: The process comprises the following steps (a) to (e): Step (a): setting two measurement positions in the main shrinkage direction of the polyester shrink film as the object to be measured, and performing measurement with the interval between the two measurement positions being L1; Step (b): a step of setting predetermined marks at two measurement positions; Step (c): heating the polyester shrink film at a temperature and for a time period specified as heat shrinkage conditions to cause heat shrinkage; Step (d): a step of setting the distance of the predetermined interval after heat shrinkage as L'1 and measuring it using the motion capture device; Step (e): a step of calculating the heat shrinkage rate in the main shrinkage direction of the polyester shrinkage film based on the following formula (1), Thermal shrinkage in the TD direction (%) = (L1-L'1) / L1×100(1).

2. The method for measuring the heat shrinkage of a polyester shrinkage film according to claim 1, wherein: The intervals between the two measurement positions in the step (a) are set a plurality of times, and the heat shrinkage rates in the TD direction are calculated in the steps (d) to (e), and the average value thereof is defined as the heat shrinkage rate in the TD direction.

3. The method for measuring the heat shrinkage of a polyester shrinkage film according to claim 1 or 2, wherein: The motion capture device is an image-type motion capture device, and the heat shrinkage rate in the TD direction is calculated based on the positions of the predetermined marks before and after heat shrinkage.

4. The method for measuring the heat shrinkage of a polyester shrinkage film according to claim 1 or 2, wherein: In the step (b), a camera is installed in advance to observe the heat shrinkage state of the polyester shrink film as the object to be measured.

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

6. The method for measuring the heat shrinkage of a polyester shrinkage film according to claim 1 or 2, wherein: The heat shrinking apparatus in the step (c) is 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.

7. The method for measuring the heat shrinkage of a polyester shrinkage film according to claim 1 or 2, wherein: In the step (d), the heat shrinkage rate in the direction perpendicular to the main shrinkage direction of the polyester shrinkage film to be measured is defined as the heat shrinkage rate in the MD direction. The heat shrinkage rate in the TD direction is measured simultaneously with the heat shrinkage rate in the MD direction using the motion capture device.

8. The method for measuring the heat shrinkage of a polyester shrinkage film according to claim 1 or 2, wherein: After the step (e), the following step is included as step (f): a step of pre-preparing a calibration curve showing the relationship between the heat shrinkage temperature and heat shrinkage time in the main shrinkage direction of the polyester shrinkage film as the measured object and the heat shrinkage rate in the TD direction, and comparing and verifying the calibration curve with the heat shrinkage rate obtained based on formula (1).

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