JP2019086456A - Packaging film manufacturing method and method for determining packaging film - Google Patents

Abstract

To provide a packaging film manufacturing method and a method for determining a packaging film quality, with which it is possible: to measure thermal diffusivity of the film without a pretreatment, and simply and with high accuracy without constraints of measurement points; and also to eliminate the risk of film contamination.SOLUTION: Provided is a packaging film manufacturing method for forming a film using a molding material containing an amorphous resin, the method including: melting and kneading a molding material containing a polyvinyl chloride resin by an extrusion molding machine; extrusion-molding a film by this extrusion molding machine and cooling the film; sandwiching the cooled film between a heater substrate 30 and a sensor substrate 32 and measuring thermal diffusivity of the film in a thickness direction by a temperature wave thermal analysis method; and determining quality of the film depending on whether or not the measured value is within a range of 1 to 9×10m/s. Since the thermal diffusivity of the film in a thickness direction is measured by a temperature wave thermal analysis method, it is possible to measure the thermal diffusivity of the film in a thickness direction with high accuracy without bringing the film into a dedicated measurement chamber.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for producing a packaging film used for preservation of food, prevention of drying, etc., and a method for determining a packaging film.

  When the dish 2 of the plate or the storage container 1 is stored, as shown in FIGS. 3 and 4, the packaging roll 3 for food is used, but the packaging roll 3 is a cylindrical roll. A core 4 is provided, and a packaging film 5 called a wrap film is wound around the core 4 by a predetermined length, and the packaging film 5 packages the storage container 1 together with the food 2. The film 5 is formed into a flexible and transparent thin film band shape by a predetermined resin-containing molding material, and is wound in multiple layers on the outer peripheral surface of the core 4 (see Patent Documents 1, 2 and 3). The predetermined resin of the film 5 is classified into a crystalline resin represented by a polyethylene (PE) resin and an amorphous resin represented by a polyvinyl chloride (PVC) resin.

  By the way, the thermal diffusivity (thermal conductivity) indicating the easiness of the temperature transmission of the film 5 is uniform in the thickness direction and the surface direction of the film 5 when the film 5 is used for food packaging having a heat retention function. It is not preferable that the film thickness is 5%, and it is preferable that the film thickness is low in the thickness direction and high in the surface direction.

  The thermal diffusivity will be described. If it is desired to improve the heat retaining property of the heated dish 2, the thermal diffusivity of the storage container 1 may be lowered, but when the storage container 1 is opened, the atmosphere is in the air. Even if the thermal diffusivity of the storage container 1 is reduced, the heat retaining property of the food 2 is reduced. Therefore, it is important that the thermal diffusivity of the film 5 for food packaging be a low value in the thickness direction of the film 5 and a high value from the viewpoint of preventing local overheating in the plane direction.

  In this regard, when the film 5 is used for packaging the food 2 and the film 5 is a crystalline resin such as polyethylene, the temperature of the food 2 is likely to decrease because the thermal diffusivity is high. On the other hand, when the film 5 is an amorphous resin such as polyvinyl chloride, the thermal diffusivity is low and the temperature does not easily decrease, so that the temperature decrease of the dish 2 can be suppressed. Furthermore, when the film 5 is an amorphous resin such as polyvinyl chloride, it is possible to omit special devices such as a multilayer extruder and a cooling / annealing device.

  From the above, for the film 5, a non-crystalline resin such as polyvinyl chloride having a low thermal diffusivity is widely used as a molding material, and the thermal diffusivity is measured by the laser flash method. In this laser flash method, a blackening material such as graphite that enhances the heat absorption is applied to the front and back surfaces of the film 5, and then the surface of the film 5 is irradiated with a pulse laser beam to uniformly pulse heat it. It is a general measurement method for determining the thermal diffusivity in the thickness direction of the film 5 by observing the diffusion of heat in the thickness direction of the film 5 as a time change of the back surface temperature of the film 5.

JP, 2016-169348, A JP, 2016-056278, A JP, 2015-229331, A

  The thermal diffusivity of the conventional film 5 is measured by the laser flash method as described above, but in the case of the measurement by the laser flash method, the film 5 is brought into a dedicated measurement chamber equipped with a laser irradiation device or the like. Otherwise, there is a problem that the thermal diffusivity in the thickness direction of the film 5 can not be measured. In addition, since it is necessary to apply a blackening material to the front and back surfaces of the film 5, it is essential to perform complicated measurement pretreatment, and there is a possibility that the film 5 may be contaminated with the application of the blackening material. . Furthermore, since the error of a measured value becomes large by the surface nonuniformity of the coating film of a blackening material, etc., it is not easy to measure the heat diffusivity of the thickness direction of the film 5 with high precision.

  The present invention has been made in view of the above, and the thermal diffusivity of the film can be measured easily and precisely without pretreatment without being restricted by the measurement points, and moreover, the possibility of contamination of the film is eliminated. It is an object of the present invention to provide a method for producing a packaging film that can be used and a method for determining a packaging film.

In the present invention, in order to solve the above-mentioned subject, it is a manufacturing method of a film for packaging which forms a film with a molding material containing resin,
The film is molded and cooled with a molding material containing an amorphous resin, and the thermal diffusivity of the film is measured by thermal wave thermal analysis, and the measured value is 1 to 9 × 10 ⁻⁸ m ² / s ^−1. It is characterized in that the quality of the film is judged by whether or not it is within the range of.

The amorphous resin can be either polyvinyl chloride resin or polyvinylidene chloride resin.
Further, after the molding material is melt-kneaded, the film is continuously extruded from the die and cooled by a cooling roll, and then the thermal diffusivity of the film can be measured by a thermal wave thermal analysis method.

  In addition, the thermal wave thermal analysis method includes a heater capable of outputting a temperature wave and a sensor capable of detecting a temperature wave from the heater, sandwiching a film between the heater and the sensor, and either the front or back of the film The thermal diffusivity of the film may be measured by changing the modulation frequency on one side and heating in an alternating current, and analyzing the phase delay of the temperature change of the other side of the film at the time of heating.

Moreover, in the present invention, in order to solve the above-mentioned subject, it is a judging method of the film for packaging which judges the quality of the film formed with the molding material containing either polyvinyl chloride resin or polyvinylidene chloride resin,
Of the thickness direction and surface direction of the film, at least the thermal diffusivity in the thickness direction is measured by thermal wave thermal analysis, and the measured value is in the range of ¹ to 9 × 10 ⁻⁸ m ² / s ⁻¹ It is characterized in that the quality of the film is judged by whether it is not or not.

  Here, the molding material in the claims may contain, in addition to the amorphous resin, an antifogging agent, a plasticizer and the like which are surfactants. The film is used at least for packaging of various foods, foodstuffs, dishes and the like, and it does not particularly ask for household, commercial and commercial applications. The thermal diffusivity of this film may be the thermal diffusivity only in the thickness direction, but may be the thermal diffusivity in the thickness direction and the surface direction. In addition, the formation of the film includes various forming methods, and at least film formation by an extrusion method and film formation by an inflation method in which the film is expanded. The thermal wave thermal analysis method is also referred to as periodic heating method, and is an analysis method of measuring the phase delay of alternating current temperature in the thickness direction of a film as a sample.

According to the present invention, the film is held between the heater and the sensor, alternating current is fed to the heater to generate a temperature wave, and the thermal diffusivity at least in the thickness direction of the film is measured by thermal wave thermal analysis. Do. At this time, unlike the amplitude, the phase of the temperature wave hardly depends on the state of the film, the thermal environment, the output of the heater, the sensitivity of the sensor, etc., so the thermal diffusivity in the film thickness direction is made highly accurate. It can be measured. In addition, when the measured value measured is in the range of 1 to 9 × 10 ⁻⁸ m ² / s ⁻¹ , at least the thermal diffusivity in the thickness direction is low, and a packaging film excellent in heat retention is obtained. be able to.

  According to the present invention, there is an effect that the thermal diffusivity of a film can be measured simply and accurately without pretreatment without being restricted in the measurement position. Moreover, since it is not necessary to apply a blackening material in the pretreatment of the film, there is an effect that the possibility of film contamination accompanying the pretreatment can be effectively eliminated.

It is whole explanatory drawing which shows typically the general embodiment of the manufacturing method of the film for packaging concerning this invention. It is explanatory drawing which shows typically the measurement principle of the thermal wave thermal analysis method in embodiment of the manufacturing method of the film for packaging which concerns on this invention. It is perspective explanatory drawing which shows the state which preserve | saves the food in a storage container with a film. It is perspective explanatory drawing which shows a packaging roll body.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. The method for producing a packaging film in the present embodiment is, as shown in FIG. 1 to FIG. The film 5 is melt-kneaded by the melt-extrusion molding machine 10, and the film 5 is molded by the T-die 14 of the melt-extrusion molding machine 10 and cooled by the cooling roll 17. of the thermal diffusivity measured at a temperature wave thermal analysis method, the measurement value is to determine the quality of the film 5 by whether a range of ^{1~9 × 10 -8 m 2 / s} -1.

  As the non-crystalline resin of the molding material 11, polyvinyl chloride (PVC) resin which is excellent in air permeability, transparency and the like and low in thermal diffusivity, and polyvinylidene chloride (PVDC) resin which is excellent in adhesiveness and the like are selected. These polyvinyl chloride resins and polyvinylidene chloride resins are characterized in that they are easy to attract water molecules which are polar molecules, because the polarity of the molecules is stronger than polyethylene (PE) resins.

  The molding material 11 is preferably added with an antifogging agent, which is a surfactant that prevents adhesion of water droplets to at least the film 5. Examples of the antifogging agent include sorbitan fatty acid ester, polyglycerin fatty acid ester, triethylene glycol and the like. This anti-fogging agent is characterized in that polyvinyl chloride resin and polyvinylidene chloride resin tend to attract water molecules that are polar molecules, so the moisture generated from the cooked food 2 etc. does not cause the inside of the film 5 to become cloudy. Function to prevent the condensed water from dropping into the dish 2 as droplets.

  As shown in FIG. 1, the melt extrusion molding machine 10 comprises, for example, a single-screw extruder, a twin-screw extruder, etc., and functions to melt and knead the input molding material 11. At the upper rear of the melt extrusion molding machine 10, a raw material inlet 12 for the molding material 11 is installed, and at this raw material inlet 12, helium gas, neon gas, argon gas, krypton gas, nitrogen gas, carbon dioxide gas The inert gas supply pipe 13 for supplying an inert gas (see the arrow in FIG. 1) as required is connected, and the inflow of the inert gas from the inert gas supply pipe 13 Oxidative deterioration and oxygen crosslinking are effectively prevented. The supply of the inert gas is optional and may or may not be supplied.

  A T-die 14 is attached to the tip of the melt-extrusion molding machine 10 through a connecting pipe, and the T-die 14 functions to continuously extrude the band-shaped film 5 downward. It is preferable that the gear pump 15 and the filter 16 be attached to the connecting pipe upstream of the T-die 14 respectively. The gear pump 15 transfers the molding material 11 melt-kneaded by the melt extruder 10 at a constant flow rate and with high accuracy to the T-die 14 through the filter 16. Further, the filter 16 separates the gel or the like of the molding material 11 in the molten state, and transfers the molding material 11 in the molten state to the T-die 14.

  A cooling roll 17 for the film 5 is rotatably supported below the T-die 14, and the cooling roll 17 is slidably nipped by a pair of rotatable pressure rolls 18; The film 5 extruded downward is inserted between the pressure roller 18 and the pressure roll 18. The cooling roll 17 is made of, for example, a metal roll having a diameter larger than that of the pressure roll 18, and holds the extruded film 5 between the pressure roll 18 and the pressure roll 18 while cooling the film 5 with a predetermined thickness. Control within the range of

  In the pair of pressure rolls 18, the winding tube 20 of the winder 19 for rolling up the film 5 is rotatably supported downstream of the pressure roll 18 downstream, and the pressure roll 18 and the winder 19 are wound. A slit blade 21 forming a slit on the side of the film 5 is movably disposed between the tube 20 and the side of the film 5, and between the slit blade 21 and the winding tube 20 of the winder 19, A required number of rotatable tension rolls 22 are supported to apply tension to the film 5 for smooth winding.

  The film 5 is extruded with a polyvinyl chloride-containing molding material 11 into a flexible transparent thin film to a thickness of about 5 to 12 μm. The film 5 has a size of 45 cm × 50 m, 45 cm × 55 m, 45 cm × 100 m, 30 cm × 30 m, 30 cm × 100 m, 30 cm × 110 m, 22 cm × 100 m, which does not eventually extend excessively, and the outer periphery of the core 4 It is wound on the surface in a multi-layered manner by a flat winding method and is used for food packaging and the like.

  The thermal wave thermal analysis method (TWA) generates Joule heat on the surface of the film 5 and focuses only on the component propagating in the thickness direction of the film 5 among the temperature waves that diffuse in all directions. It is an analysis method to observe phase delay. In this thermal wave thermal analysis method, in the measurement of the absolute value of temperature, analysis is made paying attention to the point that the phase is hardly affected although the disturbance on the measurement such as the contact resistance is strongly influenced.

  As shown in FIG. 2, the thermal wave thermal analysis method outputs a temperature wave of alternating current (see the arrow in FIG. 2) and detects a heater substrate 30 which can propagate and a diffused temperature wave from the heater substrate 30. And the film 5 is sandwiched between the heater substrate 30 and the sensor substrate 32. Then, the modulation frequency is changed on the surface of the film 5 to heat it in an alternating current state. The thermal diffusivity in the thickness direction of the film 5 is measured by analyzing the phase delay of the temperature change on the back surface of the film 5 at the time of heating.

  As the heater 31 of the heater substrate 30, for example, a microheater made of Peltier element or the like is used, and a weak sine wave power is supplied to generate a temperature wave on the surface of the film 5. Further, as the sensor 33 of the sensor substrate 32, in order to detect a minute temperature wave, for example, a temperature sensor such as a metal thin film (for example, Au or Pt) by sputtering or an acrylic plate is adopted.

  The analysis principle of the thermal wave thermal analysis method will be described in detail. Periodic heat generation j (t) of angular frequency ω on the surface (x = 0) of the film 5 of thickness d sandwiched between the heater substrate 30 and the sensor substrate 32 When the film 5 is thermally thick enough, the temperature modulation on the back surface of the film 5 (x = d) is delayed in phase as compared to the temperature modulation on the film 5 surface, and the amplitude intensity is attenuated. Do.

Here, focusing only on the phase difference of temperature, the phase difference Δθ is expressed by the difference of the phase between the plane of x = 0 and the plane of x = d as follows.
Phase difference Δθ = √ω / 2α · d−π / 4
Here, α is the thermal diffusivity (m ² / s).

  According to this equation, the film thickness 5 is known by changing the angular frequency ω on the surface and heating it in an alternating current state by measuring the phase delay Δθ of the temperature change on the back surface of the film 5. The thermal diffusivity α in the direction can be determined. In this measurement, the thermal diffusivity is determined by the phase difference of temperature change on the front and back surfaces of the film 5 which is the heating surface, so that it is possible to perform high-accuracy measurement without requiring any absolute value of temperature.

  In addition, as a measuring apparatus which measures the thermal diffusivity of the thickness direction of the film 5 by a thermal wave thermal analysis method, the portable small-sized measuring apparatus by Advanced Riko Co., Ltd. and Hitachi High-Tech Science Co., Ltd. can be mentioned. . Further, with regard to the thermal diffusivity in the surface direction of the film 5, the film 5 is wound in a roll shape and cut in the radial direction, and the cut roll film 5 is used together with the heater substrate 30 and the sensor substrate 32 of the measuring device. The thermal diffusivity of the film 5 in the surface direction can be measured by thermal wave thermal analysis. About the thermal diffusivity of the surface direction of this film 5, it is also possible to measure with the measuring apparatus of a light alternating current method etc. FIG.

The quality of the film 5 is determined by the thermal diffusivity in the thickness direction of the film 5 being 1 to 9 × 10 ⁻⁸ m ² / s ⁻¹ , preferably 3 to 8.5 × 10 ⁻⁸ m ² / s ^−. It is judged by whether it is in the range of 5 to 8 × 10 ⁻⁸ m ² / s ⁻¹ , more preferably ¹ . This indicates that the thickness of the film 5 at the time of cooking 2 packaging by the film 5 from the experimental results if the thermal diffusivity in the thickness direction of the film 5 is in the range of ¹ to 9 × 10 ⁻⁸ m ² / s ⁻¹ This is because the thermal diffusivity in the longitudinal direction decreases, and improvement in heat retention can be expected.

  In the above, in the case of producing the film 5 for food packaging, first, the molding material 11 is put into the raw material inlet 12 of the melt extrusion molding machine 10 and melt-kneaded. The film 5 is continuously extruded in the form of a strip. After the film 5 is thus extruded, the film 5 is cooled by the cooling roll 17 while being wound around the cooling roll 17, the pair of pressure rolls 18, the tension roll 22, and the winding tube 20 of the winding machine 19. After cutting the both sides of each with the slit blade 21, it winds up on the winding tube 20 one by one.

  As a method of bringing the film 5 into close contact with the cooling roll 17, it is preferable to adopt a touch roll method in which the pressure roll 18 presses the film 5 against the circumferential surface of the cooling roll 17 to adhere the film 5. . The contact time between the film 5 and the cooling roll 17 is not particularly limited, but is preferably 0.1 to 120 seconds, preferably 0.5 to 60 seconds, more preferably 1 to 30 seconds. .

  After the film 5 is wound around the take-up tube 20, the film 5 is held between the heater substrate 30 and the sensor substrate 32 of the measuring apparatus in an inspection process before product shipment, and AC is supplied to the heater 31 to transmit temperature waves. Then, the thermal diffusivity in the thickness direction of the film 5 is measured by thermal wave thermal analysis. At this time, unlike the amplitude, the phase of the temperature wave does not depend on the state of the film 5, the thermal environment, the output of the heater 31, the sensitivity of the sensor 33, etc. Can be measured with high accuracy and at high speed.

As a result of the measurement, when the measured value is in the range of ¹ to 9 × 10 ⁻⁸ m ² / s ⁻¹ , it is judged that the thermal diffusivity in the thickness direction of the film 5 is appropriate. Judge as good product and ship. On the other hand, when the measured value is out of the range of ¹ to 9 × 10 ⁻⁸ m ² / s ⁻¹ , it is judged that the thermal diffusivity in the thickness direction of the film 5 is inappropriate, and the film 5 is Determine the product as a defective product and interrupt the shipment. By determining the quality of the film 5 as described above, it is possible to manufacture a film 5 for food packaging which has a low thermal diffusivity in the thickness direction and is excellent in heat retention.

  According to the above, since the thermal diffusivity of the film 5 can be measured by the thermal wave thermal analysis method using a portable measuring device at the production site of the film 5 or the like, the film 5 can be measured in a dedicated measurement room apart from the production site. The thermal diffusivity in the thickness direction of the film 5 can be measured simply, accurately, and quickly without the comparison sample. Moreover, since it is not necessary to blacken the front and back surfaces of the film 5, it is possible to omit complicated pretreatment of the measurement, and effectively eliminate the possibility of the contamination of the film 5 caused by the application of the blackening agent. be able to.

  In addition, since the error of the measured value does not increase due to the surface unevenness of the coating film of the blackening material, the measurement environment, and the like, the thermal diffusivity in the thickness direction of the film 5 can be measured with high accuracy. Furthermore, if the film 5 made of polyvinyl chloride resin having a low thermal diffusivity in the thickness direction is used, the film 5 is less likely to be condensed during food packaging, and water droplets fall from the film 5 onto the food 2 and rot It is possible to prevent

In addition, although polyvinyl chloride resin was mainly used as an amorphous resin in the said embodiment, it is not limited to this at all. For example, the thermal diffusivity of the film 5 made of polyvinylidene chloride resin is measured by a thermal wave thermal analysis method using polyvinylidene chloride (PVDC) resin having excellent adhesion and the like as the amorphous resin, and the measured values are 1 to The quality of the film 5 may be determined based on whether it is in the range of 9 × 10 ⁻⁸ m ² / s ⁻¹ or not.

  Further, in the above embodiment, the thermal diffusivity in the thickness direction of the film 5 was measured by the thermal wave thermal analysis method in the inspection step before product shipment, but immediately after cooling by the cooling roll 17, the heat in the thickness direction of the film 5 The diffusivity may be measured. Further, immediately after the film 5 is wound around the winding tube 20, the thermal diffusivity in the thickness direction of the film 5 may be measured.

Hereafter, the Example of the determination method of the film for packaging which concerns on this invention is demonstrated with a comparative example.
Example 1
Prepare five films of polyvinyl chloride resin (PVC) which is an amorphous resin [Shin-Etsu Polymer Co., Ltd. product name: Polymer wrap (registered trademark, the same shall apply hereinafter)], and use the five films as a heater of the measuring device. Then, the heater was supplied with an alternating current to generate a temperature wave, and the thermal diffusivity in the thickness direction of the film was measured by a temperature wave thermal analysis method.

  The five films had thicknesses of 7.4 μm, 7.3 μm, 7.8 μm, 6.7 μm, 6.8 μm, and an average thickness of 7.2 μm. Moreover, although the thermal diffusion of the film thickness direction was measured at room temperature of 23 degreeC, room temperature rose 1-2 degreeC during measurement. The measuring apparatus used the apparatus (product name ai-Phase Mobile 1 ustandard-alone mode) made from eye phase corporation | Co., Ltd. | KK.

  When the thermal diffusivity in the thickness direction of the five films was measured sequentially, the measured value of each film and the average value of the measured values were described in Table 1, and the heat retention of the film was tested and evaluated. As for the test method of heat retention of film, since JIS is not specified, food warmed at 80 ° C is stored in a storage container made of polypropylene resin, and the opening of this storage container is covered with a film and left for 1 hour After one hour, the film was removed from the opening of the storage container, and the surface temperature of the dish in the storage container was measured.

Example 2
Five sheets of another film (Shin-Etsu Polymer Co., Ltd. product name: Polymer Wrap R) made of polyvinyl chloride resin (PVC) were prepared, and the heat diffusivity in the thickness direction of each film was measured in the same manner as in Example 1 It was measured by temperature wave thermal analysis. The five films had thicknesses of 8.8 μm, 8.5 μm, 8.3 μm, 9.5 μm, 9.4 μm, and an average thickness of 8.9 μm.
When the thermal diffusivity in the thickness direction of the five films was measured sequentially, the measured value of each film and the average value of this measured value are described in Table 1, and the heat retention of the film was tested in the same manner as in Example 1 evaluated.

[Example 3]
Five sheets of another polyvinyl chloride resin (PVC) film (Shin-Etsu Polymer Co., Ltd .: product name: Antibacterial polymer wrap) are prepared, and the heat diffusivity of each film in the thickness direction is the same as in Example 1 It was measured by temperature wave thermal analysis. The five films had a thickness of 6.8 μm, 6.8 μm, 7.0 μm, 6.9 μm, 7.1 μm, and an average thickness of 6.9 μm.
When the thermal diffusivity in the thickness direction of the five films was measured sequentially, the measured value of each film and the average value of this measured value are described in Table 1, and the heat retention of the film was tested in the same manner as in Example 1 evaluated.

Example 4
Prepare five films made of amorphous resin, polyvinylidene chloride resin (PVDC) (made by Kleha Co., Ltd .: product name Klerap (registered trademark, the same in the following)) in the same manner as in Example 1 except for each film. The thermal diffusivity in the thickness direction of was measured by thermal wave thermal analysis. The five films had a thickness of 10.2 μm, 10.0 μm, 9.7 μm, 9.8 μm, 9.6 μm, and an average thickness of 9.9 μm.
After sequentially measuring the thermal diffusivity in the thickness direction of the five films, the measured value of each film and the average value of the measured values are described in Table 2, and the heat retention of the film was tested in the same manner as in Example 1 evaluated.

Comparative Example
Prepare five films of polyethylene resin (PE), a crystalline resin (made by Japan Cooperative Cooperative Association: product name polyethylene wrap mini), and sandwich these five films between heater and sensor of the measuring device sequentially Then, the heater was supplied with an alternating current to generate a temperature wave, and the thermal diffusivity in the thickness direction of the film was measured by a thermal wave thermal analysis method.

The five films had thicknesses of 9.6 μm, 8.1 μm, 9.7 μm, 8.1 μm, 12.0 μm, and an average thickness of 9.5 μm. Moreover, although the thermal diffusion of the film thickness direction was measured at room temperature of 23 degreeC, room temperature rose 1-2 degreeC during measurement. Moreover, the measuring apparatus used the apparatus (product name ai-Phase Mobile 1 ustandard-alone mode) made from eye phase corporation | Co., Ltd. | KK.
After sequentially measuring the thermal diffusivity in the thickness direction of the five films, the measured value of each film and the average value of the measured values are described in Table 2, and the heat retention of the film was tested in the same manner as in Example 1 evaluated.

In the case of each example, the thermal diffusivity in the thickness direction of the film is in the range of ¹ to 9 × 10 ⁻⁸ m ² / s ⁻¹ , and even in the film heat retention test, the surface temperature of the dish is It did not decrease much and showed excellent heat retention.
On the other hand, in the case of the comparative example, the thermal diffusivity in the thickness direction of the film is out of the range of ¹ to 9 × 10 ⁻⁸ m ² / s ⁻¹ , and the heat retention test of the film The surface temperature was lower than in the example.

  In addition, about the heat retention property of a film, it is possible to test based on A method (isothermal method) of JISL1096. It is also possible to test using a ThermoLab II tester.

  The method for producing a packaging film and the method for determining a packaging film according to the present invention are used in the field of film production, inspection, and the like.

Reference Signs List 1 storage container 2 cooking 3 packaging roll 5 film 10 melt extrusion molding machine 11 molding material 14 T die 17 cooling roll 18 crimping roll 19 winding machine 20 winding tube 30 heater substrate 31 heater 32 sensor substrate 33 sensor

Claims (4)

A manufacturing method of a packaging film for forming a film with a resin-containing molding material, the film is molded with an amorphous resin-containing molding material and cooled, and the thermal diffusivity of the film is measured by a thermal wave thermal analysis method. The manufacturing method of the film for packaging characterized by judging the quality of a film based on whether the measured value which was measured is in the range of 1-9 * 10 < ^-8 > m < ² > / s < ^-1 >.   The method for producing a packaging film according to claim 1, wherein the amorphous resin is any one of polyvinyl chloride resin and polyvinylidene chloride resin.   The thermal wave thermal analysis method comprises a heater capable of outputting a temperature wave and a sensor capable of detecting a temperature wave from the heater, sandwiching a film between the heater and the sensor, and either the front or the back of the film The thermal diffusivity of the film is measured by changing the modulation frequency on the surface and heating in an alternating current, and analyzing the phase delay of the temperature change on the other surface of the film at the time of heating. Method for producing packaging film. It is a determination method of the film for packaging which determines the quality of the film shape | molded by the molding material containing either polyvinyl chloride resin and polyvinylidene chloride resin,
Of the thickness direction and surface direction of the film, at least the thermal diffusivity in the thickness direction is measured by thermal wave thermal analysis, and the measured value is in the range of ¹ to 9 × 10 ⁻⁸ m ² / s ⁻¹ A method of determining a packaging film, comprising determining whether the film is good or not by whether the film is good or bad.

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