Film manufacturing method

Abstract

This invention provides a film manufacturing method that enables the production of high-quality films using recycled materials. [Solution] A method for manufacturing a film includes: a repelling step of manufacturing recycled pellets by pelletizing recycled raw materials including crushed film; a measuring step of measuring the fluidity of the recycled pellets; a management step of managing the recycled pellets by lot based on the measured fluidity; a selection step of selecting a lot of recycled pellets to be used to constitute the arbitrary layer from a plurality of lots of recycled pellets based on the fluidity of the arbitrary layer to be included in the film to be manufactured; and a manufacturing step of manufacturing the film using the recycled pellets of the lot selected in the selection step.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a film.

Background Art

[0002] Patent Document 1 discloses a quality control method for measuring the fluidity of recycled raw materials, managing recycled raw materials whose fluidity is within a first range for first shipment, and managing recycled raw materials whose fluidity is within a second range for second shipment.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] <x An object of the present invention is to provide a method for manufacturing a film that can manufacture a high-quality film using recycled raw materials.

Means for Solving the Problems

[0005] The method for manufacturing a film according to the first aspect of the present invention includes a re-pelletizing step of manufacturing re-pellets by pelletizing recycled raw materials including crushed films, a measuring step of measuring the fluidity of the re-pellets, a management step of lot-managing the re-pellets based on the measured fluidity, a selecting step of selecting a lot of the re-pellets to be used for forming an arbitrary layer from a plurality of lots of the re-pellets based on the fluidity of an arbitrary layer included in the film to be manufactured, and a manufacturing step of manufacturing the film using the lot of re-pellets selected in the selecting step.

[0006] In the above-described film manufacturing method, in the selection step, a lot of recycled pellets with fluidity close to that of the desired layer is selected, and the recycled pellets from the selected lot are used in the film manufacturing process. As a result, a high-quality film can be manufactured.

[0007] A method for manufacturing a film according to a second aspect of the present invention is a method for manufacturing a film according to a first aspect, wherein in the manufacturing step, the film is manufactured using a film material obtained by mixing recycled pellets from a lot selected in the selection step with virgin raw material of any layer.

[0008] In the above-described film manufacturing method, a film raw material consisting of recycled pellets mixed with virgin raw materials is used in the production of the film. Therefore, a higher quality film can be manufactured.

[0009] A method for manufacturing a film according to a third aspect of the present invention is a method for manufacturing a film according to a second aspect, wherein in the manufacturing step, the mixing ratio of the recycled pellets and the virgin raw material is determined based on the difference between the fluidity of the recycled pellets and the fluidity of the arbitrary layer.

[0010] The smaller the difference between the fluidity of the recycled pellets and the fluidity of any given layer, the smaller the proportion of virgin raw material in the film raw material can be. On the other hand, in order to produce a high-quality film, the larger the difference between the fluidity of the recycled pellets and the fluidity of any given layer, the larger the proportion of virgin raw material in the film raw material can be. In the above film manufacturing method, the mixing ratio of recycled pellets and virgin raw material can be appropriately determined.

[0011] A method for manufacturing a film according to a fourth aspect of the present invention is a method for manufacturing a film according to a third aspect, wherein in the manufacturing step, the mixing ratio of the recycled pellets and the virgin raw material is determined such that the fluidity of the film raw material falls within a predetermined range including the fluidity of any layer.

[0012] According to the above film manufacturing method, the proportion of recycled pellets in the film raw material can be increased.

[0013] A method for manufacturing a film according to a fifth aspect of the present invention is a method for manufacturing a film according to a fourth aspect, wherein in the manufacturing step, the mixing ratio of the recycled pellets and the virgin raw material is determined such that the fluidity of the film raw material is included in a first predetermined range that includes the fluidity of any layer at a first temperature, and in a second predetermined range that includes the fluidity of any layer at a second temperature.

[0014] According to the above film manufacturing method, the fluidity of the film raw materials at multiple temperatures is close to that of any given layer, making it possible to manufacture films of higher quality.

[0015] A method for manufacturing a film according to the sixth aspect of the present invention is a method for manufacturing a film according to any one of the first to fifth aspects, wherein in the control step, in addition to the fluidity of the recycled pellets, the recycled pellets are lot-controlled based on at least one of the optical properties, color, purity, and shape of the recycled pellets.

[0016] According to the above film manufacturing method, recycled pellets are lot-controlled based on detailed considerations, making it possible to manufacture higher quality films.

[0017] A method for manufacturing a film according to a seventh aspect of the present invention includes: a measurement step of measuring the fluidity of recycled raw materials including crushed film; a management step of managing the crushed film by lot based on the measured fluidity; a selection step of selecting a lot of the crushed film to be used to constitute the arbitrary layer from a plurality of lots of the crushed film based on the fluidity of the arbitrary layer to be included in the film to be manufactured; and a manufacturing step of manufacturing the film using the crushed film of the lot selected in the selection step.

[0018] In the method for manufacturing the film, in the selection step, a lot of crushed films with fluidity close to that of an arbitrary layer is selected, and the selected lot of crushed films is used for manufacturing the film. Therefore, a film of high quality can be manufactured.

[0019] The method for manufacturing a film according to the eighth aspect of the present invention is the method for manufacturing a film according to the seventh aspect, wherein in the management step, in addition to the fluidity of the crushed film, the crushed film is lot-managed based on at least one of the optical properties, color appearance, purity, and shape of the crushed film.

[0020] According to the method for manufacturing the film described above, since the crushed films are lot-managed based on detailed aspects, a film of even higher quality can be manufactured.

[0021] The method for manufacturing a film according to the ninth aspect of the present invention is the method for manufacturing a film according to any one of the first to eighth aspects, wherein the crushed film has been subjected to a deinking treatment.

[0022] According to the method for manufacturing the film described above, since the crushed film does not have a printed layer, a film of higher quality can be manufactured.

Effects of the Invention

[0023] According to the method for manufacturing a film according to the present invention, a film of high quality can be manufactured using recycled raw materials.

Brief Description of the Drawings

[0024] [Figure 1] Cross-sectional view of the film. [Figure 2] Table showing the relationship between the film number and the fluidity of the inner layer. [Figure 3] Flowchart showing an example of the film manufacturing process. [Figure 4] Table showing the relationship between the lot of recycled pellets and the fluidity.

Modes for Carrying Out the Invention

[0025] A method for manufacturing a film according to one embodiment of the present invention will be described below with reference to the drawings.

[0026] [First Embodiment] <1. Overview> Figure 1 is a cross-sectional view showing an example of the layer structure of film 100. Film 100 includes outer layers 10 and 20, an inner layer 30, and an adhesive layer 40. The material constituting the outer layers 10 and 20 is, for example, a polyester resin. Polyester resins include, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, or polybutylene naphthalate. In this embodiment, the material constituting the outer layers 10 and 20 is polyethylene terephthalate. The inner layer 30 is laminated between the outer layer 10 and the outer layer 20. The material constituting the inner layer 30 is, for example, a styrene resin. Styrene resins include, for example, polystyrene, acrylonitrile styrene, acrylonitrile butadiene styrene, or copolymers with conjugated dienes. In this embodiment, the material constituting the inner layer 30 is polystyrene. The adhesive layer 40 includes a first adhesive layer 41 and a second adhesive layer 42. The first adhesive layer 41 joins the outer layer 10 and the inner layer 30. The second adhesive layer 42 joins the outer layer 20 and the inner layer 30. The material constituting the adhesive layer 40 is, for example, an adhesive such as a polyester elastomer. The film 100 has a printed layer on which product descriptions and other information are laminated at arbitrary positions and is used by being attached to a PET bottle or the like.

[0027] Figure 2 is a table showing the relationship between the product number of film 100 and the fluidity of the inner layer 30. Film 100 has multiple product numbers, even if the layer structure is the same, for example, with different ratios of the inner layer 30 to the outer layer 10 and outer layer 20. These multiple product numbers include, for example, product numbers A101, A102, and A103. In film 100 of product numbers A101, A102, and A103, the fluidity of the inner layer 30 differs at the first temperature TA and the second temperature TB. An index for evaluating the fluidity of the inner layer 30 is, for example, MFR (Melt Flow Rate). The fluidity of the inner layer 30 is measured by a known melt flow indexer. In this embodiment, the second temperature TB is higher than the first temperature TA. Preferably, the second temperature TB is the temperature of the resin when it passes through the die when film 100 is extruded. Note that the MFR values ​​shown in Figure 2 are examples.

[0028] Laminated films containing multiple types of layers, such as film 100, are commonly known. Generally, when films are produced using recycled raw materials obtained from laminated films, the appearance of the film deteriorates and the performance of the film decreases, making the recycling of laminated films difficult.

[0029] In the film manufacturing method of this embodiment, due to the ingenuity employed, it is possible to manufacture a high-quality film even when using recycled raw materials recovered from laminated films. The film manufacturing method of this embodiment will be described in detail below.

[0030] <2. Film manufacturing method> Figure 3 is a flowchart showing an example of the film manufacturing process in the film manufacturing method of this embodiment. Prior to the steps shown in this flowchart, a deinking treatment is performed on the waste film to remove the printed layer. The deinked waste film is crushed and becomes recycled raw material containing numerous film fragments (hereinafter referred to as "crushed film"). The recycled raw material includes outer layers 10 and 20, an inner layer 30, and an adhesive layer 40. In this embodiment, the case in which the recycled raw material is used as the material constituting the inner layer 30 will be described.

[0031] In step S11 (re-pelletization step), the recycled raw material, including the crushed film, is pelletized by the film manufacturing equipment to produce recycled pellets.

[0032] In step S12 (measurement step), the MFR value of the recycled pellet is measured using a melt flow indexer. In step S12, the MFR value of the recycled pellet is measured at the first temperature TA and the second temperature TB. The MFR value of the recycled pellet can be measured, for example, based on "JIS K7210-1 Plastics - Method for determining melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastic plastics - Part 1: Standard test methods".

[0033] In step S13 (control step), recycled pellets are lot-controlled based on the measured MFR value. Figure 4 shows an example of lot-control of recycled pellets. The properties of crushed film vary greatly depending on, for example, the environment in which the film was used and the environment in which the discarded film was stored. Therefore, the MFR value of recycled pellets manufactured from recycled raw materials including crushed film also varies according to the properties of the crushed film. As shown in Figure 4, by lot-controlling recycled pellets based on the MFR value, it is possible to easily select recycled pellets having a suitable MFR value for use in constructing the inner layer 30 of the film 100 to be manufactured.

[0034] In step S14 (selection step), a lot of recycled pellets to be used to constitute the inner layer 30 is selected from a plurality of recycled pellet lots RA to RC based on the fluidity of the inner layer 30 of the film 100 to be manufactured. In this embodiment, in step S14, the lot of recycled pellets to be used to constitute the inner layer 30 is selected by comparing the MFR value of the inner layer 30 at a second temperature TB with the MFR value of the recycled pellets of lots RA to RC at a second temperature TB. Alternatively, the lot of recycled pellets to be used to constitute the inner layer 30 may be selected by comparing the MFR value of the inner layer 30 at a first temperature TA with the MFR value of the recycled pellets of lots RA to RC at a first temperature TA.

[0035] For example, when manufacturing film 100 of product number A101 shown in Figure 2, recycled pellets from lot RA, which have an MFR value close to the MFR value of the inner layer 30 of film 100 of product number A101 at the second temperature TB, are selected. When manufacturing film 100 of product number A102, recycled pellets from lot RB, which have an MFR value close to the MFR value of the inner layer 30 of film 100 of product number A102 at the second temperature TB, are selected. When manufacturing film 100 of product number A103, recycled pellets from lot RC, which have an MFR value close to the MFR value of the inner layer 30 of film 100 of product number A103 at the second temperature TB, are selected. Note that in step S14, the operator may select the lot, or the lot may be selected by a computer executing a program stored in a storage device.

[0036] In step S15 (manufacturing step), a film raw material is produced by mixing the recycled pellets of the lot selected in step S14 with the virgin raw material for the inner layer 30 using a manufacturing apparatus. Preferably, the mixing ratio of recycled pellets and virgin raw material is determined based on the difference between the MFR value of the recycled pellets of the selected lot and the MFR value of the inner layer 30 of the film 100 to be manufactured. For example, the smaller the difference between the MFR value of the recycled pellets of the selected lot and the MFR value of the inner layer 30 of the film 100 to be manufactured, the smaller the proportion of virgin raw material in the film raw material will be. The larger the difference between the MFR value of the recycled pellets of the selected lot and the MFR value of the inner layer 30 of the film 100 to be manufactured, the larger the proportion of virgin raw material in the film raw material will be.

[0037] In step S15, it is preferable that the mixing ratio of recycled pellets and virgin raw materials be determined such that the MFR value of the film raw material falls within a predetermined range that includes the MFR value of the inner layer 30. The predetermined range is a range in which high quality of the film 100 can be maintained. The predetermined range includes a first predetermined range and a second predetermined range. The first predetermined range is a range with the median MFR value at the first temperature TA shown in Figure 2. The second predetermined range is a range with the median MFR value at the second temperature TB shown in Figure 2. The first and second predetermined ranges are, for example, a range of -20g / 10min to +20g / 10min with the median MFR value of the inner layer 30. Generally, the MFR value of recycled pellets is higher than that of virgin raw materials, so the film raw material mixed with recycled pellets and virgin raw materials will have a higher MFR value than the inner layer 30 shown in Figure 2. In step S15, it is preferable to determine the mixing ratio of recycled pellets and virgin raw materials such that the MFR value of the film raw material falls within the first predetermined range and the second predetermined range. The relationship between the mixing ratio of recycled pellets and virgin raw materials for lots RA to RC and the MFR values ​​of the film raw material at the first temperature TA and the second temperature TB has been determined in advance through testing.

[0038] In step S16 (manufacturing step), film 100 is manufactured using film raw materials by a manufacturing apparatus.

[0039] <3. Effects of the First Embodiment> In the film manufacturing method of the first embodiment, in the selection step, a lot of recycled pellets having an MFR value close to the MFR value of the inner layer 30 is selected, and the film raw material obtained by mixing the recycled pellets of the selected lot with virgin raw material is used in the production of the film. Since the molecular weight of the film raw material is kept at a certain size, a higher quality film can be produced compared to when the film is produced using only recycled raw material.

[0040] [Second Embodiment] The film manufacturing method of the second embodiment differs from the first embodiment in that it does not have a repelletization step S11, but the other configurations are substantially the same as those of the first embodiment. In the following, the same content as the first embodiment will be omitted from the explanation, and the focus will be on the parts that differ from the first embodiment.

[0041] In the second embodiment, the film manufacturing method omits the repelling step S11 of the first embodiment, and in the measurement step S12, the fluidity of the recycled raw material, including the crushed film, is measured. The film manufacturing method of this embodiment is realized by replacing the term "recycled pellets" with "crushed film" in the descriptions of the control step S13, selection step S14, and manufacturing steps S15 and S16 of the first embodiment.

[0042] In the film manufacturing method of the second embodiment, since the crushed film is not pelletized, the thermal history of the recycled raw material is reduced. Because the recycled raw material is less prone to deterioration, a higher quality film can be manufactured.

[0043] [Third Embodiment] The film manufacturing method of the third embodiment differs from that of the first embodiment in the control step S13, but the other components are substantially the same as those of the first embodiment. In the following, the same content as the first embodiment will be omitted from the explanation, and the parts that differ from the first embodiment will be described in detail. Note that the control step S13 of this embodiment can also be applied to the second embodiment by replacing the word "recycled pellets" with "crushed film".

[0044] In the control step S13 of the film manufacturing method of the third embodiment, recycled pellets are lot-controlled by classifying the recycled pellets, which have been classified based on the fluidity of the recycled pellets, based on at least one of optical properties, color, purity, and shape.

[0045] The optical properties of recycled pellets include, for example, haze, gloss, and at least one of total light transmittance. Using recycled pellets with low optical properties in film production will degrade the optical properties of the film. Therefore, by managing the lot size of recycled pellets while considering their optical properties, it is possible, for example, to limit the amount of recycled pellets with low optical properties used, or to preferentially use recycled pellets with low optical properties in the production of films where high quality is not required.

[0046] The color of recycled pellets includes, for example, a color value. The color value can be measured based on, for example, "JIS Z8730 Method of color representation - Color difference of objects." Recycled pellets with low color values, in other words, deteriorated pellets, are yellowed, and the films manufactured from them will also be yellowed. Therefore, by considering the color of recycled pellets and managing the lot of recycled pellets accordingly, it is possible to, for example, limit the amount of recycled pellets with low color values ​​used, or to preferentially use recycled pellets with low color values ​​in the manufacture of films where high quality is not required.

[0047] The purity of recycled pellets includes, for example, at least one of the following: moisture content, ash content, pH value, density, and number of defects.

[0048] The moisture content is measured, for example, by the loss on drying method. If the moisture content of recycled pellets is high, there is a risk of air bubbles forming during film formation. Therefore, by managing the recycled pellets by considering their moisture content, for example, by pre-drying recycled pellets when using those with high moisture content, it is possible to manufacture high-quality films.

[0049] Ash content can be measured, for example, based on "JIS K2272 Crude oil and petroleum products - Test methods for ash content and sulfated ash content." By measuring the ash content of recycled pellets, the amount of impurities that cause defects can be quantified. Therefore, by managing the lot size of recycled pellets while considering their ash content, it is possible to, for example, limit the amount of recycled pellets with high ash content used, or to preferentially use recycled pellets with high ash content in the manufacture of films where high quality is not required.

[0050] The pH value can be obtained, for example, by adding crushed film to pure water at a predetermined concentration, stirring for a certain period of time, and then measuring the pH value of the solution. Alkaline aqueous solutions are generally used for deinking waste film. If alkaline aqueous solution adheres to the surface of deinked crushed film, hydrolysis of the raw materials (mainly polyethylene terephthalate and nylon) may occur when the crushed film is fed into an extruder. Therefore, by managing the crushed film by lot while considering its pH value, high-quality film can be produced by, for example, pre-washing crushed film with water to remove any residue of the alkaline aqueous solution when using crushed film with a high pH value.

[0051] Density can be measured, for example, based on "JIS K7112 Plastics - Method for measuring density and specific gravity of non-foamed plastics." If the density of recycled pellets is low, there is a risk of air bubbles forming during film formation. Therefore, by managing the lot of recycled pellets while considering their density, it is possible to, for example, limit the amount of low-density recycled pellets used, or to preferentially use low-density recycled pellets in the manufacture of films where high quality is not required. Furthermore, the production of low-density recycled pellets can be suppressed by adjusting the vacuum level and melting temperature during recycled pellet manufacturing.

[0052] The number of defects can be measured, for example, by manufacturing a sample sheet using recycled pellets by a melt extrusion method and counting the number of defects at predetermined intervals on the sample sheet using an inspection machine installed in front of the sample sheet winding device. If the number of defects in the recycled pellets is high, the quality of the film will deteriorate. Therefore, by managing the recycled pellets by lot while considering the number of defects, it is possible to, for example, limit the amount of recycled pellets with many defects used, or to preferentially use recycled pellets with many defects in the manufacture of films where high quality is not required.

[0053] The shape of recycled pellets includes, for example, their size. The size is determined, for example, by taking a predetermined number of recycled pellets and basing it on their weight. If there is a large variation in the size of recycled pellets, there is a risk of transportation problems with the recycled raw material or mixing problems when mixing with virgin raw material. Therefore, by managing the recycled pellets by lot while considering their size, it is possible to suppress the use of recycled pellets with large size variations. Furthermore, the variation in the size of recycled pellets can be suppressed by adjusting the pelletizing speed and extrusion rate during the manufacturing of recycled pellets.

[0054] <4. Variation> The embodiments described above are illustrative of possible forms of the film manufacturing method according to the present invention and are not intended to limit its form. The film manufacturing method according to the present invention may take forms different from those illustrated in each embodiment. One example is a form in which a part of the configuration of each embodiment is replaced, modified, or omitted, or a form in which a new configuration is added to the embodiment. Several examples of modifications of each embodiment are shown below. Note that the following modifications can be combined with each other to the extent that they are not technically contradictory.

[0055] <4-1> In each of the above embodiments, in step S15 of the film manufacturing process, a film raw material was produced by mixing recycled pellets from the lot selected in step S14 with virgin raw material for the inner layer 30. However, the film manufacturing process is not limited to this. For example, in the film manufacturing process, step S15 may be omitted, and in step S16, the film 100 may be produced using only recycled pellets from the lot selected in step S14.

[0056] <4-2> In each of the above embodiments, in step S15 of the film manufacturing process, the mixing ratio of recycled pellets and virgin raw materials was determined such that the MFR value of the film raw materials falls within a first predetermined range and a second predetermined range. However, the method for determining the mixing ratio of recycled pellets and virgin raw materials is not limited to this. For example, in step S15 of the film manufacturing process, the mixing ratio of recycled pellets and virgin raw materials may be determined such that the MFR value of the film raw materials falls within only one of the first predetermined range or the second predetermined range.

[0057] <4-3> In each of the above embodiments, the MFR values ​​of the recycled pellets were measured at the first temperature TA and the second temperature TB in step S12 (measurement step) of the film manufacturing process. However, the MFR values ​​of the recycled pellets may also be measured at either the first temperature TA or the second temperature TB. In this modified example, when extruding the film 100 at either the first temperature TA or the second temperature TB, it is preferable to measure the MFR values ​​of the recycled pellets at a temperature close to the temperature of the resin as it passes through the die.

[0058] <4-4> In each of the above embodiments, recycled raw materials including crushed film were used as the material constituting the inner layer 30 of the film 100. However, the layers of the film 100 in which recycled raw materials including crushed film are used as materials are not limited to these. For example, recycled raw materials including crushed film may be used as materials constituting the outer layers 10 and 20 of the film 100. In this modified example, in step S14 (selection step) of the film manufacturing process, a lot of recycled pellets to be used to constitute the outer layers 10 and 20 is selected from a plurality of recycled pellet lots RA to RC based on the fluidity of the outer layers 10 and 20 of the film 100 to be manufactured.

[0059] <4-5> In each of the above embodiments, a laminated film having multiple layers was manufactured using recycled raw materials including crushed film. However, the structure of the film manufactured using recycled raw materials including crushed film is not limited thereto. For example, a single-layer film may be manufactured using recycled raw materials including crushed film.

[0060] <4-6> In each of the above embodiments, the materials constituting the outer layers 10, 20 and the inner layer 30 of the film 100 can be arbitrarily selected.

[0061] In the first example, the adhesive layer 40 may be omitted, and the materials constituting the outer layers 10, 20 and the inner layer 30 of the film 100 may be the same type of resin material. Examples of the same type of resin material include polyester resins, styrene resins, polypropylene resins, polyethylene resins, or polyamide resins. Examples of polyethylene resins include branched low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or high-density polyethylene (HDPE). Examples of polyamide resins include aliphatic polyamides or aromatic polyamides. In the first example, it is preferable to use recycled raw materials as the material constituting the inner layer 30.

[0062] When the materials constituting the outer layers 10, 20 and the inner layer 30 of the film 100 are polyester resin or styrene resin, the film 100 can be used, for example, as a heat-shrinkable film for PET bottles.

[0063] When the materials constituting the outer layers 10, 20 and the inner layer 30 of the film 100 are polypropylene resins, the film 100 can be used, for example, as a packaging film.

[0064] When the materials constituting the outer layers 10, 20 and the inner layer 30 of the film 100 are polyethylene resins, the film 100 can be used, for example, as a backgrinding film or a dicing substrate film.

[0065] When the materials constituting the outer layers 10, 20 and the inner layer 30 of the film 100 are polyamide resins, the film 100 can be used, for example, as packaging for food products.

[0066] In the first example, the materials constituting the outer layers 10 and 20 and the inner layer 30 may be exactly the same, or there may be differences between the materials constituting the outer layers 10 and 20 and the materials constituting the inner layer 30, for example, as follows: For example, considering the shrinkage and barrier performance of the film 100, different resin materials of different part numbers or resin materials of different compositions may be used for the outer layers 10 and 20 and the inner layer 30. Antiblocking agents (AB agents) and other resin types may be added to the materials constituting the outer layers 10 and 20 to exhibit properties that depend on the surface condition of the film 100, such as heat sealability, printability, slipperiness, and adhesion. In addition, resin colorants (MB-COLOR) may be added to the materials constituting the outer layers 10 and 20 to color the film 100.

[0067] In the second example, the adhesive layer 40 may be omitted, and the materials constituting the outer layers 10 and 20 of the film 100 and the materials constituting the inner layer 30 may be different materials. In the first specific example of the second example, the materials constituting the outer layers 10 and 20 of the film 100 are polyethylene resin, and the material constituting the inner layer 30 is polypropylene resin. In this specific example, the film 100 is used as a backgrinding film or a dicing substrate film. In the first specific example, it is preferable to use recycled raw materials as the material constituting the inner layer 30.

[0068] In the second specific example of the second example, the materials constituting the outer layers 10 and 20 of the film 100 are cyclic olefin copolymers, and the material constituting the inner layer 30 is a polypropylene resin. In the second specific example, the film 100 is used, for example, as a heat-shrinkable film for PET bottles. In the second specific example, it is preferable to use recycled materials as the material constituting the inner layer 30.

[0069] In the third specific example of the second example, the materials constituting the outer layers 10 and 20 of the film 100 are polyamide resins, and the material constituting the inner layer 30 is an ethylene-vinyl alcohol copolymer. In the third specific example, the film 100 is used as packaging for food and the like. In the third specific example, it is preferable to use recycled raw materials as the materials constituting the outer layers 10 and 20. Since polyamide resins and ethylene-vinyl alcohol copolymers are incompatible, when recycled raw materials are used as the material constituting the inner layer 30 of the film 100 having the layer structure of the third specific example, the inner layer 30 becomes cloudy. Furthermore, since the inner layer 30, which is composed of ethylene-vinyl alcohol copolymer, is a layer that contributes to gas barrier performance, the barrier performance deteriorates if other resins are included. Since ethylene-vinyl alcohol copolymer is a reactive resin, agglomerates (gels) are generated when other resin types are mixed in. From this viewpoint, in the third specific example, it is undesirable to use recycled raw materials as the material constituting the inner layer 30.

[0070] In the fourth specific example of the second example, the materials constituting the outer layers 10 and 20 of the film 100 are polyethylene resin, and the material constituting the inner layer 30 is polyamide resin. In the fourth specific example, the film 100 is used as packaging for food and the like. In the fourth specific example, it is preferable to use recycled materials as the materials constituting the outer layers 10 and 20.

[0071] <4-7> In the embodiments described above, MFR (Melt Volume Rate) was used as an index for evaluating liquidity, but MVR (Melt Volume Rate) may also be used as an index for evaluating liquidity. [Explanation of Symbols]

[0072] S11: Repelling step S12: Measurement step S13: Management Steps S14: Selection Step S15: Manufacturing Steps S16: Manufacturing Steps

Claims

1. A re-pelletization step to produce recycled pellets by pelletizing recycled raw materials including crushed film, A measurement step for measuring the fluidity of the recycled pellets, A management step of lot-controlling the recycled pellets based on the measured fluidity, A selection step of selecting a lot of recycled pellets from a plurality of lots of recycled pellets to be used to constitute the arbitrary layer, based on the fluidity of any layer contained in the film to be manufactured, The manufacturing step includes manufacturing the film using recycled pellets from the lot selected in the selection step. A method for manufacturing film.

2. In the manufacturing step, the film is manufactured using a film raw material obtained by mixing recycled pellets from the lot selected in the selection step with virgin raw material from any of the layers. A method for manufacturing a film according to claim 1.

3. In the manufacturing step, the mixing ratio of the recycled pellets and the virgin raw material is determined based on the difference between the fluidity of the recycled pellets and the fluidity of the arbitrary layer. A method for manufacturing a film according to claim 2.

4. In the manufacturing step, the mixing ratio of the recycled pellets and the virgin raw material is determined such that the fluidity of the film raw material falls within a predetermined range that includes the fluidity of any given layer. A method for manufacturing a film according to claim 3.

5. In the aforementioned manufacturing step, The fluidity of the aforementioned film raw material is The fluidity of any of the layers at the first temperature is included in a first predetermined range, and The mixing ratio of the recycled pellets and the virgin raw material is determined so that it falls within a second predetermined range, including the fluidity of any of the layers at the second temperature. A method for manufacturing a film according to claim 4.

6. In the control step, the recycled pellets are lot-controlled based on at least one of the optical properties, color, purity, and shape of the recycled pellets, in addition to the fluidity of the recycled pellets. A method for manufacturing a film according to any one of claims 1 to 5.

7. A measurement step to measure the fluidity of recycled raw materials including crushed film, A control step of lot-controlling the crushed film based on the measured fluidity, A selection step of selecting a lot of the crushed film to be used to constitute the arbitrary layer from a plurality of lots of the crushed film, based on the fluidity of any layer contained in the film to be manufactured, A manufacturing step includes manufacturing the film using the crushed film of the lot selected in the selection step. A method for manufacturing film.

8. In the control step, the crushed film is lot-controlled based on at least one of the optical properties, color, purity, and shape of the crushed film, in addition to the fluidity of the crushed film. A method for manufacturing a film according to claim 7.

9. The aforementioned shredded film has been subjected to a deinking treatment. A method for manufacturing a film according to any one of claims 1 to 8.

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