Film

Abstract

In one embodiment of the present invention, deterioration in quality due to polypropylene can be suppressed in a film in which polypropylene is dispersed in polyethylene. In the film according to the one embodiment of the present invention, a dispersed phase is dispersed in a matrix phase. The film comprises a matrix phase containing polyethylene and a dispersed phase containing polypropylene. The dispersed phase comprises at least flat phases oriented in the MD direction, and the average aspect ratio of the flat phases is 15 or more.

Description

film

[0001] The present invention relates to a film comprising polyethylene.

[0002] Techniques for recycling polyethylene films are known (see, for example, Patent Document 1). In the technique described in Patent Document 1, a special washing process is performed to thoroughly wash away mud and other substances adhering to used polyethylene films used in fields, etc., so that the films can be recycled as new polyethylene films.

[0003] There is also known a technology for recycling waste resin films whose main component is a resin other than polyethylene as one component of polyethylene film (see, for example, Patent Document 2). This technology makes it possible to reduce the amount of virgin polyethylene used in the production of polyethylene film by the amount of waste resin film used.

[0004] JP 2002-052532 A JP 2004-182957 A

[0005] In a film according to one embodiment of the present invention, a dispersed phase is dispersed in a matrix phase. The film includes a matrix phase containing polyethylene and a dispersed phase containing polypropylene. The dispersed phase includes flat phases oriented at least in the machine direction, and the flat phases have an average aspect ratio of 15 or more.

[0006] In one embodiment of the present invention, a method for producing a film having a dispersed phase dispersed in a matrix phase includes: kneading a first raw material, which is made of polyethylene and constitutes the matrix phase, with a second raw material, which contains polypropylene as a component of the dispersed phase, and forming the mixture into a film. The ratio ηB / ηA of the viscosity ηB of the polypropylene contained in the second raw material at a molding temperature to the viscosity ηA of the first raw material at the molding temperature during film molding is 0.015 or more and less than 1.

[0007] FIG. 1 is a diagram schematically showing a partial cross section of a film according to one embodiment of the present invention. FIG. 2 is a flowchart showing a method for producing the film. FIG. 3 is a TEM image of a cross section of a kneaded product obtained in a kneading step. FIG. 4 is a TEM image of a MD cross section of a film obtained in a film molding step. FIG. 5 is a TEM image of a TD cross section of a film obtained in a film molding step. FIG. 6 is a TEM image of a MD cross section of a film according to a comparative example. FIG. 7 is a TEM image of a MD cross section of a film according to Example 4. FIG. 8 is a TEM image of a MD cross section of a film according to Example 24. Detailed Description of the Invention

[0008] Because absorbent articles such as diapers and sanitary napkins contain many resin-based components, recycling waste absorbent articles is highly significant. However, when polypropylene, which is commonly found in absorbent articles, is used as a component of polyethylene film, the qualities of the polyethylene film, such as strength, elongation, and smoothness to the touch, are easily impaired.

[0009] The present invention relates to suppressing deterioration in quality due to polypropylene in a film in which polypropylene is dispersed in polyethylene.

[0010] A film according to one embodiment of the present invention and a method for producing the same will be described.

[0011] [Film Structure] The film according to this embodiment has a matrix phase and a dispersed phase, and has a structure in which the dispersed phase is dispersed in the matrix phase. The matrix phase contains polyethylene. The dispersed phase has a flat phase containing polypropylene.

[0012] In FIG. 1 , the left-right direction of the paper corresponds to the MD direction (machine direction: resin molding flow direction) of the film, the depth direction of the paper corresponds to the TD direction (transverse direction: direction perpendicular to MD) of the film, and the up-down direction of the paper corresponds to the thickness direction of the film. Each flat phase of the film according to this embodiment has a flat shape with an aspect ratio of 5 or more, and is oriented in at least the MD direction in the in-plane direction, and preferably also oriented in the TD direction. Furthermore, the average aspect ratio of the flat layer, defined as the average value of the aspect ratios in the flat phase of the film according to this embodiment, is 15 or more, preferably 20 or more. Furthermore, from the viewpoint of maintaining good low-temperature heat sealability, the average aspect ratio of the flat phase of the film according to this embodiment is preferably 100 or less, more preferably 50 or less. Each flat phase preferably extends in all in-plane directions, but may also extend only in the MD direction to form a band-like or needle-like shape.

[0013] Furthermore, the film according to this embodiment preferably contains, as a dispersed phase, a spherical phase composed of a resin and having an aspect ratio of 3 or less. The spherical phase contributes to improving the tear strength of the film. The spherical phase may contain, for example, at least one of polyethylene terephthalate and polyurethane. In the film according to this embodiment, the content of the resin constituting the spherical phase is preferably 0.05% by mass or more and 20% by mass or less. In the film according to this embodiment, the average particle size of the spherical phase is preferably 1 nm or more and 2 μm or less.

[0014] The aspect ratio of each dispersed phase is measured using TEM images captured using a transmission electron microscope (TEM). The film to be observed is processed into ultrathin sections using an ultramicrotome and stained with a heavy metal (ruthenium tetroxide), allowing the presence and absence of the matrix phase and dispersed phase to be observed. The observation surface of the film sample is an MD cross section formed by cutting parallel to the MD direction. The observation magnification is set to 2500x or more, so as to obtain a rectangular field of view with an in-plane dimension of 14.3 μm or more and a thickness dimension of 14.3 μm or more. A HT7820 (manufactured by Hitachi High-Tech Corporation) is used as the transmission electron microscope, and the acceleration voltage is set to 100 kV. In this embodiment, TEM images of the film sample can be used to measure not only the aspect ratio of each dispersed phase but also the cross-sectional area of ​​each dispersed phase. This makes it possible to evaluate the content of the dispersed phase in the film and the ratio of the flat phase and spherical phase in the dispersed phase based on the cross-sectional area ratio.

[0015] Image analysis software Image-Pro10 (Media Cybernetics) was used to measure the aspect ratio and cross-sectional area of ​​each dispersed phase observed in the TEM image of the film sample. The imported TEM image was scaled using the "Quick Space Construction Function," and the "Smart (Learning Function)" was used to randomly surround 10 points around the dispersed phase (object) and matrix phase (background), allowing learning to extract all dispersed phases. The "radius ratio" and "cross-sectional area" were then measured with the "Fill in the Hole" target extraction option selected. This radius ratio for each dispersed phase was treated as the aspect ratio of the dispersed phase. In this embodiment, dispersed phases with an aspect ratio of 5 or greater were considered flat phases, and those with an aspect ratio of 3 or less were considered spherical phases. Dispersed phases with a radius ratio of 5 or greater were extracted from the measurement results, and the average value of the radius ratios of the extracted dispersed phases was used as the average aspect ratio of the flat phases. The sum of the cross-sectional areas of dispersed phases with a radius ratio of 5 or greater was used as the total cross-sectional area of ​​the flat phases. Further, dispersed phases having a radius ratio of 3 or less are extracted from the measurement results, and the average value of the radius ratios of the extracted dispersed phases is defined as the average aspect ratio of the spherical phase, and the sum of the cross-sectional areas of the dispersed phases having a radius ratio of 3 or less is defined as the total cross-sectional area of ​​the spherical phase. The sum of the cross-sectional areas of all dispersed phases included in the measurement results is defined as the total cross-sectional area of ​​the dispersed phase. The field area of ​​the TEM image is defined as the total cross-sectional area of ​​the film. By using these, various cross-sectional area ratios for the film can be determined. For example, the ratio of the total cross-sectional area of ​​the dispersed phases to the total cross-sectional area of ​​the film, the ratio of the total cross-sectional area of ​​the flat phases to the total cross-sectional area of ​​the dispersed phases, and the ratio of the total cross-sectional area of ​​the spherical phases to the total cross-sectional area of ​​the dispersed phases can be determined.

[0016] In the film according to this embodiment, the flat phases are all interrupted in the in-plane direction, so that the matrix phase is continuous in the thickness direction. In other words, the structure in which the flat phases are dispersed in the matrix phase in the film according to this embodiment differs from a laminate structure in which the matrix phase and the flat phase are alternately laminated in the thickness direction as a series of layers in the in-plane direction.

[0017] In this embodiment, since the dimensions of each flat phase in each MD cross section are small relative to the film thickness, the physical properties of each flat phase are unlikely to affect the physical properties of the film as a whole. Furthermore, in the film according to this embodiment, the thin flat phases are widely present in the in-plane direction, and the polypropylene constituting the flat phases is widely dispersed in the in-plane direction, so the influence of the polypropylene is not localized, and uniform physical properties are likely to be obtained along the in-plane direction. Furthermore, in the film according to this embodiment, since the polypropylene is present as a flat phase, the impact of the polypropylene on the feel is unlikely to be large, and the inherent smooth feel of polyethylene is likely to be obtained.

[0018] For this reason, in the film according to this embodiment, the physical properties of the polyethylene constituting the matrix phase are dominant, regardless of the physical properties of the polypropylene constituting the flat phase. In other words, the film according to this embodiment is likely to achieve high strength, high elongation, and a smooth feel comparable to films composed only of polyethylene, regardless of the presence of polypropylene. In the film according to this embodiment, it is preferable that the proportion of the flat phase in the entire dispersed phase is large. From this perspective, in the film according to this embodiment, it is preferable that the ratio of the total cross-sectional area of ​​the flat phase to the total cross-sectional area of ​​the dispersed phase in the TEM image is 60% or more. Furthermore, in the film according to this embodiment, it is preferable that the ratio of the total cross-sectional area of ​​the spherical phase to the total cross-sectional area of ​​the film in the TEM image is 0.05% or more and 20% or less.

[0019] Therefore, the film according to the present embodiment can recycle waste containing polypropylene derived from various products as one component, thereby reducing the amount of virgin polyethylene used in the film according to the present embodiment and thereby reducing the environmental impact associated with production.

[0020] Examples of waste containing polypropylene include waste derived from absorbent articles such as sanitary napkins, baby diapers, adult diapers, etc. Examples of waste derived from absorbent articles include used absorbent articles, absorbent articles determined to be defective before shipping, and offcuts generated during the manufacturing process of absorbent articles.

[0021] Examples of polypropylene-containing waste that can be recovered from absorbent articles include resin fibers and resin films. The technology according to the present embodiment expands the possibilities for recycling by enabling waste containing mixed resin fibers and resin films to be successfully reused as resin films that are strong, have high elongation, and are smooth to the touch. Furthermore, since the resins contained in absorbent articles often have higher melting points than polyethylene, blending waste derived from absorbent articles makes it easier to achieve high heat resistance, and the effect can be expected to increase as the aspect ratio of the flat phase increases.

[0022] In the film according to the present embodiment, the lower the polyethylene content and the higher the polypropylene content, the more difficult it is to obtain high strength, high elongation, and a smooth feel. From this viewpoint, in the film according to the present embodiment, the ratio of the cross-sectional area of ​​polyethylene to the total cross-sectional area of ​​the film in a TEM image of the film taken with a transmission electron microscope is preferably 50% or more, more preferably 80% or more. The cross-sectional area of ​​polyethylene in the TEM image can be determined as the cross-sectional area of ​​the matrix phase, obtained by subtracting the total cross-sectional area of ​​the dispersed phase from the total cross-sectional area of ​​the film, assuming that the region occupied by polyethylene and the region occupied by the matrix phase coincide. In the film according to the present embodiment, the ratio of the cross-sectional area of ​​polypropylene to the total cross-sectional area of ​​the film in a TEM image of the film taken with a transmission electron microscope is preferably 50% or less, more preferably 20% or less. The cross-sectional area of ​​polypropylene in the TEM image can be determined as the cross-sectional area of ​​the flat phase, assuming that the region occupied by polypropylene and the region occupied by the flat phase coincide. Furthermore, in the film according to this embodiment, the polyethylene content is preferably 50% by mass or more, more preferably 80% by mass or more, and the polypropylene content is preferably 50% by mass or less, more preferably 20% by mass or less.

[0023] Furthermore, in the film according to this embodiment, it is preferable to reduce the amount of virgin polyethylene used within a range that ensures sufficient quality depending on the application. From this perspective, in the film according to this embodiment, the ratio of the cross-sectional area of ​​polyethylene to the total cross-sectional area of ​​the film in a TEM image of the film taken with a transmission electron microscope is preferably 99% or less, more preferably 80% or less. In addition, in the film according to this embodiment, the ratio of the cross-sectional area of ​​polypropylene to the total cross-sectional area of ​​the film in a TEM image of the film taken with a transmission electron microscope is preferably 1% or more, more preferably 20% or more. Furthermore, in the film according to this embodiment, the polyethylene content is preferably 99% by mass or less, more preferably 80% by mass or less. In addition, in the film according to this embodiment, the polypropylene content is preferably 1% by mass or more, more preferably 20% by mass or more.

[0024] The film according to this embodiment may contain a flat phase as the dispersed phase, the main component of which is not polypropylene. Furthermore, the film according to this embodiment may contain a phase other than the flat phase and the spherical phase as the dispersed phase. This allows the film according to this embodiment to achieve improved quality due to the dispersed phase other than the flat phase and the spherical phase. In this embodiment, the term "main component" refers to a component whose content is 50% or more.

[0025] For example, the film according to this embodiment preferably contains at least one of a styrene-based elastomer, an ethylene-α-olefin copolymer (including those in which ethylene is present as a comonomer), an olefin-based resin having a polar group introduced therein, and a styrene-based resin having a polar group introduced therein. These components have the effect of aiding dispersion and enhancing the performance of the resin, thereby contributing to improvements in the tensile elongation, tensile strength, and tear strength of the film. In the film according to this embodiment, the content of the resin constituting this phase is preferably 0.5% by mass or more and 15% by mass or less. Methods for introducing polar groups include graft polymerization, in which monomers are grafted together using an electron beam; the use of a monomer containing a polar group during polymer synthesis; plasma treatment; and corona treatment.

[0026] Furthermore, the film according to this embodiment preferably includes an inorganic material phase composed of an inorganic material as the dispersed phase. Examples of inorganic materials constituting the inorganic material phase include calcium carbonate and titanium oxide, which contribute to improving tear strength and suppressing ultraviolet light transmission. From the viewpoint of molding stability, the content of the inorganic material in the film according to this embodiment is preferably 0% by mass or more and 60% by mass or less. In addition, in the film according to this embodiment, when determining the content (mass percentage, ratio of cross-sectional area in TEM image) of the resin component constituting the matrix phase and dispersed phase in a configuration including an inorganic material phase, the presence of the inorganic material phase (mass, cross-sectional area in TEM image) is excluded from the calculation.

[0027] In the film according to the present embodiment, from the viewpoint of reducing production costs, it is preferable that the materials constituting the phases other than the flat phase in the dispersed phase are as much as possible made up of components contained in the waste together with polypropylene. However, in the film according to the present embodiment, any of these materials may be added separately from the polypropylene.

[0028] The use of the film according to this embodiment is not particularly limited. As an example, the film according to this embodiment can be used as a packaging film for various products. Examples of products suitable for use as a packaging film for the film according to this embodiment include sanitary products, baby diapers, adult diapers, and household goods.

[0029] The film according to this embodiment preferably has desirable properties as a packaging film. For example, the film according to this embodiment preferably has high tensile elongation, tensile strength, and tear strength in order to obtain high durability as a packaging film. Specifically, the film according to this embodiment preferably has a tensile elongation of 700% or more, more preferably 900% or more. Furthermore, the film according to this embodiment preferably has a tensile strength per unit cross-sectional area of ​​0.23 N / (μm cm) or more, more preferably 0.30 N / (μm cm) or more. Furthermore, the film according to this embodiment preferably has a tear strength per unit thickness of 0.015 N / μm or more, more preferably 0.045 N / μm or more.

[0030] In this embodiment, the tensile elongation and tensile strength of a film are measured as follows. A dumbbell-shaped No. 3 sample is prepared by punching out the film to be measured in the direction of the tensile test. The thickness of the necked portion of the sample is measured with a micrometer, and the result is taken as thickness C (μm). The punched sample is fixed to a tensile tester (product name: AG-1S, manufactured by Shimadzu Corporation) with the chuck distance set to 50 mm. After fixing, the load read by the tensile tester is set to zero, and the sample is stretched at a deformation rate of 300 mm / min until it breaks. The tensile elongation and tensile strength are calculated from the obtained data by reading the elongation amount A (mm) and load B (N) during the stretching process and combining this with the thickness C (μm) measured in advance, as follows. The tensile elongation and tensile strength of the film are calculated as the average values ​​of three samples in each of the MD and TD directions. Tensile elongation (%) = 100 x A (mm) / 20 mm Tensile strength (N / (μm cm)) = B (N) / 0.5 cm / C (μm)

[0031] In this embodiment, the tear strength of a film is measured as follows. A film is cut into a sample measuring 63 mm long and 76 mm wide to match the tear test direction, and the cut sample is secured to an Elmendorf tear tester (analog type, manufactured by Toyo Seiki Seisakusho, Ltd.). The number of films secured is adjusted appropriately so that the measurement results fall within 20 to 80% of the measurement range. The thickness of each film is measured in advance using a micrometer, and the average value is taken as E (μm). The pendulum is lifted and stopped, and the pointer is set to the starting position. The sample is carefully attached to the gripping tool, and after firmly tightening the clamp, a 20 mm long slit is made with the attached knife. The tear strength is measured by carefully releasing the pendulum, and the force required to tear the sample is read off the scale D. This value is converted to tear strength (N) per sheet, and divided by the thickness E (μm) measured with a thickness gauge to calculate tear strength per thickness (N / μm). The tear strength of the film is determined as the average value of three samples in each of the MD and TD directions.

[0032] Furthermore, the film according to this embodiment preferably has a good feel as a packaging film. To obtain a smooth feel, it is preferable that the MMD (variation in coefficient of friction) and SMD (surface roughness) measured by the KES surface test are small. In other words, the smaller the MMD and SMD measured by the KES surface test, the smoother the feel of the film. In the film according to this embodiment, the higher the average aspect ratio of the flat phase, the smaller the MMD and SMD tend to be. Specifically, in the film according to this embodiment, the MMD measured by the KES surface test is preferably 0.05 or less, and more preferably 0.025 or less. In addition, in the film according to this embodiment, the SMD measured by the KES surface test is preferably 3.0 or less, and more preferably 1.5 or less.

[0033] The KES surface test method according to this embodiment is as follows. A sample cut to 200 mm x 200 mm from the film to be measured is placed in an automated surface tester (product name: KES-FB4-A-SE, manufactured by Kato Tech Co., Ltd.) with the measurement surface facing the outside of the balloon during inflation molding and the measurement direction facing the MD direction, and tension is applied using a bar weight (147.8 g). Using the KES-FB SYSTEM data measurement program (KES-FB System Ver. 8.03WJ / For WinXP, 7), the device is operated at a speed of 0.1 cm / sec (SENS STD) to measure friction and roughness, and the MMD and SMD values ​​are read. The MMD and SMD of the film are calculated as the average values ​​of three samples. The friction measurement conditions are a static load of 50 gf and a dedicated 10 mm square piano wire sensor as the probe. The roughness measurement conditions are a static load of 10 gf and a dedicated 0.5 mm roughness sensor as the measuring probe.

[0034] Furthermore, since the film according to this embodiment has fine irregularities, it is easier to obtain a unique visual texture with a matte feel compared to a film composed only of polyethylene. In this regard, in the film according to this embodiment, in order to more effectively obtain such a visual texture as a packaging film, the surface gloss is preferably 80 or less, and more preferably 30 or less. The gloss value is measured by attaching a gloss meter (product name: HP-300, manufactured by Time Group Co., Ltd.) to the film to be measured. However, if the measured value is 100 or more, the gloss value is set to 100. The gloss value of the film is calculated as the average value of the values ​​measured at five points. Furthermore, the film according to this embodiment scatters external light with fine irregularities, thereby suppressing the transmission of ultraviolet rays. Therefore, when used as, for example, a packaging film, deterioration of the contents due to ultraviolet rays from sunlight is less likely to occur, and high protection performance for the contents is easily achieved.

[0035] In addition, the film according to this embodiment may be used as a packaging film, with characters or designs representing product names and other product information printed on its surface. In this regard, the film according to this embodiment is preferably subjected to a surface treatment such as corona treatment to achieve high printability on the surface, thereby achieving a surface wettability of 40 mN / m or greater. Wettability is evaluated as surface energy. Specifically, to evaluate the wettability of a film, several centimeters of 40 mN / m Dyne Pen ink is applied to the film, and the film is observed to maintain this state for 2 to 4 seconds. Specifically, the film's wettability is determined to be 40 mN / m or greater if the above observation is performed three times and the applied state is maintained without forming droplets all three times.

[0036] [Film Manufacturing Method] An example of a film manufacturing method according to this embodiment will be described below with reference to Fig. 2, but the film manufacturing method according to this embodiment is not limited to the example shown in Fig. 2. The film manufacturing method shown in Fig. 2 includes a raw material preparation step (step S01), a kneading step (step S02), and a film molding step (step S03).

[0037] (Step S01: Raw Material Preparation) In step S01, raw materials for the film according to this embodiment are prepared. Specifically, in step S01, a first raw material and a second raw material are prepared. The first raw material is virgin polyethylene that constitutes the matrix phase. The second raw material is recycled material containing polypropylene that constitutes the flat phase of the dispersed phase.

[0038] The first raw material can be prepared, for example, as commercially available polyethylene pellets. The second raw material can be prepared, for example, as pellets obtained by repellenting waste containing polypropylene. The repellenting conditions for the second raw material can be determined appropriately depending on the physical properties of the components constituting the waste.

[0039] The second raw material preferably contains, as a component constituting the spherical phase, at least one of a thermoplastic resin and a thermosetting resin having a melting point 100° C. or more higher than that of the first raw material. Such a component may include, for example, at least one of polyethylene terephthalate and polyurethane.

[0040] The second raw material may also contain at least one of a styrene-based elastomer, an ethylene-α-olefin copolymer, an olefin-based resin having a polar group introduced therein, and a styrene-based resin having a polar group introduced therein. Furthermore, the second raw material may also contain an inorganic material that constitutes the inorganic material phase.

[0041] The viscosity ηA of the first raw material made of polyethylene is adjusted according to the viscosity ηB of the polypropylene contained in the second raw material. More specifically, the viscosity ηA of the first raw material is adjusted based on the molding temperature during film molding in step S03, so that the ratio ηB / ηA of the viscosity ηB to the viscosity ηA at the molding temperature is 0.015 or more and less than 1.

[0042] The viscosity ηA of the first raw material and the viscosity ηB of the polypropylene contained in the second raw material are measured as follows. The resin is filled into the barrel of a capillograph (trade name: CAPIROGRAPH 1B, manufactured by Toyo Seiki Seisakusho) that has been heated to the measurement temperature in advance, and the viscosity value (Pa s) is read from the load when the piston is extruded at a speed of 10 mm / min in the "Capillary Flow Test" mode of the program "Capillograph of Windows (registered trademark)". A nozzle with a diameter of 1 mm and a length of 10 mm is used, and a barrel with a diameter of 9.55 mm is used.

[0043] (Step S02: Kneading) In step S02, the first raw material and the second raw material prepared in step S01 are kneaded to produce a kneaded product. Figure 3 is a TEM image of a cross section of the kneaded product obtained in step S02, taken with a transmission electron microscope. In the structure shown in Figure 3, a light-colored dispersed phase is dispersed in a dark-colored matrix phase.

[0044] The matrix phase is primarily composed of polyethylene and may contain polyethylene that constitutes one component of the second raw material in addition to the polyethylene that constitutes the first raw material. In the structure shown in Figure 3, the dispersed phase primarily composed of polypropylene appears as relatively large circular regions, and the other dispersed phases appear as fine dot-like regions.

[0045] At the stage of the kneaded material obtained in step S02, the dispersed phase containing polypropylene as the main component is in a spherical shape with an average aspect ratio of not more than 3. In this embodiment, in the process of molding the kneaded material into a film in step S03, the dispersed phase containing polypropylene as the main component is made into a flat shape with an average aspect ratio of not less than 5, thereby forming a flat phase.

[0046] In the film according to the present embodiment, as described above, the polypropylene-based dispersed phase is a flat phase, which allows the polypropylene to be widely dispersed in the in-plane direction. Therefore, in the present embodiment, there is little need to increase the dispersibility of the polypropylene-based dispersed phase to a highly fine level in the kneading step S02.

[0047] For this reason, in step S02, it is preferable to use a single-screw extruder rather than a twin-screw extruder or other advanced kneading technique from the viewpoint of reducing the number of steps. This allows the production cost of the film according to this embodiment to be reduced. However, if necessary, a twin-screw extruder may be used, or a single-screw extruder and a twin-screw extruder may be used in combination.

[0048] In step S02, it is advantageous to have a small viscosity ratio between polyethylene and polypropylene and a small interfacial tension between the matrix phase and the dispersed phase in order to make the dispersed phase finer. From this viewpoint, the kneading temperature in step S02 is preferably 200° C. or higher and 300° C. or lower. In step S02, it is preferable that the temperatures of all regions through which the raw materials pass, except for the raw material supply port, during the process of producing the kneaded product in the extruder, are within the above range, but the temperatures in some regions may be outside the above range.

[0049] (Step S03: Film Forming) In step S03, the kneaded material prepared in step S02 is thinly stretched to form a film. The viscosity ηA of the first raw material is adjusted so that the ratio ηB / ηA of the viscosity ηB to the viscosity ηA at the forming temperature is 0.015 or more and less than 1, so that the dispersed phase mainly composed of polypropylene becomes a flat phase during the stretching of the kneaded material.

[0050] In other words, in this embodiment, by setting the ratio ηB / ηA at the molding temperature within the above range, the matrix phase is stretched without being affected by the polypropylene, and at the same time, the dispersed phase containing polypropylene as the main component is deformed in accordance with the deformation of the matrix phase. As a result, the dispersed phase containing polypropylene as the main component, which is stretched thin together with the matrix phase, becomes a flat phase.

[0051] In the film manufacturing method according to the present embodiment, it has been found that by relatively increasing the molding temperature of the kneaded material in step S03, the ratio ηB / ηA of the viscosity ηB to the viscosity ηA at the molding temperature tends to remain less than 1. Furthermore, a high molding temperature is advantageous for suppressing the force of the deformed flat phase returning to a spherical shape due to interfacial tension. However, excessively increasing the molding temperature can lead to problems such as poor moldability and resin degradation. From these perspectives, the molding temperature of the kneaded material in step S03 is preferably 200°C or higher and 300°C or lower, and more preferably 215°C or higher and 280°C or lower. Furthermore, when polyethylene terephthalate is included in the raw material, it is preferable to set the molding temperature above the melting point of polyethylene terephthalate and melt the polyethylene terephthalate once. As a result, although fibrous polyethylene terephthalate is often included in absorbent articles, polyethylene terephthalate contained in the raw material in a non-spherical form can also be converted into a spherical phase.

[0052] Figure 4 is a TEM image of the MD cross section of the film obtained in step S03, taken with a transmission electron microscope. Figure 5 is a TEM image of the TD cross section of the film obtained in step S03, taken with a transmission electron microscope. The matrix phase is the same as the matrix phase of the kneaded product shown in Figure 3. In Figures 4 and 5, the left-right and depth directions of the paper correspond to the in-plane directions of the film, and the up-down direction of the paper corresponds to the thickness direction of the film. In the structure shown in Figures 4 and 5, it can be seen that the circular dispersed phase mainly composed of polypropylene shown in Figure 3 has been stretched thin to form a flat phase.

[0053] The method for forming the kneaded material into a film according to the present embodiment is not limited to a specific method, but it is preferable to use an inflation molding method, which can efficiently stretch the film not only in the MD direction but also in the TD direction, thereby suppressing the influence of polypropylene not only in the MD direction but also in the TD direction.

[0054] The film molding machine used in inflation molding can be configured, for example, as an integral unit with the extruder used for kneading, so as to receive the kneaded material directly from the extruder. The molding temperature in inflation molding refers to the temperature of the kneaded material at the time when it is discharged from the die. In inflation molding, the temperature of the kneaded material is preferably 200°C or higher and 300°C or lower, more preferably 215°C or higher and 280°C or lower, throughout the entire process from the time when the kneaded material is discharged from the extruder to the completion of subsequent molding. However, in inflation molding, the temperature of the kneaded material may be outside the above range at any time other than the time when it is discharged from the extruder.

[0055] [Other Embodiments] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the gist of the present invention.

[0056] For example, the film manufacturing method according to the present embodiment may include other steps as needed. For example, after the film forming step, a surface treatment may be performed to modify the surface of the film. One example of such a surface treatment is a corona treatment to improve the wettability of the film surface. Furthermore, after the film forming step, slits may be formed or a bag-making process may be performed.

[0057] Furthermore, in the film manufacturing method according to this embodiment, a kneaded product obtained by adding other materials to recycled material may be used as the second raw material. Furthermore, in the film manufacturing method according to this embodiment, the second raw material does not need to be recycled material; for example, virgin polypropylene or a kneaded product obtained by adding other materials to virgin polypropylene may be used. In addition, in the film manufacturing method according to this embodiment, the first raw material may not be virgin material, but may be recycled waste material containing polyethylene. Furthermore, in the film manufacturing method according to this embodiment, other materials may be added and kneaded in the kneading step, separate from the first raw material and the second raw material.

[0058] Furthermore, with respect to the above-described embodiment, the present invention further discloses the following configurations. <1> A film having a dispersed phase dispersed in a matrix phase, the film comprising a matrix phase containing polyethylene and a dispersed phase containing polypropylene, wherein the dispersed phase includes flat phases oriented at least in the machine direction, and the flat phases have an average aspect ratio of 15 or more. <2> The film according to <1>, wherein in an image of the film taken with a transmission electron microscope, the ratio of the total cross-sectional area of ​​the flat phases to the total cross-sectional area of ​​the dispersed phases is 60% or more. <3> The film according to <1> or <2>, wherein the dispersed phase is made of a resin and further includes a spherical phase having an aspect ratio of 3 or less. <4> The film according to <3>, wherein the spherical phase includes at least one of polyethylene terephthalate and polyurethane. <5> The film according to any one of <1> to <4>, wherein the dispersed phase further includes an inorganic material phase. <6> The film according to any one of <1> to <5>, wherein, in an image of the film taken with a transmission electron microscope, the ratio of the total cross-sectional area of ​​the polyethylene to the total cross-sectional area of ​​the film is 50% or more and 99% or less. <7> The film according to any one of <1> to <6>, wherein, in an image of the film taken with a transmission electron microscope, the ratio of the total cross-sectional area of ​​the polypropylene to the total cross-sectional area of ​​the film is 1% or more and 50% or less. <8> The film according to any one of <1> to <7>, wherein the tensile elongation is 700% or more. <9> The film according to any one of <1> to <8>, wherein the tensile strength is 0.23 N / (μm cm) or more. <10> The film according to any one of <1> to <9>, wherein the tear strength is 0.015 N / μm or more. <11> The film according to any one of <1> to <10>, wherein the MMD measured by the KES surface test is 0.05 or less. <12> The film according to any one of <1> to <11>, having an SMD of 3.0 or less according to a KES surface test. <13> The film according to any one of <1> to <12>, having a surface gloss of 80 or less. <14> The film according to any one of <1> to <13>, having a surface wettability of 40 mN / m or more.<15> The film according to any one of <1> to <14>, wherein waste derived from absorbent articles is used as part of the raw materials. <16> A method for producing a film having a dispersed phase dispersed in a matrix phase, comprising: kneading a first raw material containing polyethylene and constituting the matrix phase with a second raw material containing polypropylene as a component constituting the dispersed phase, and molding the resulting mixture into a film; and wherein the ratio ηB / ηA of the viscosity ηB of the polypropylene contained in the second raw material at a molding temperature during film molding to the viscosity ηA of the first raw material at the molding temperature during film molding is 0.015 or more and less than 1. <17> The second raw material comprises waste derived from absorbent articles. <18> A method for producing a film according to <16> or <17>, wherein the first raw material and the second raw material are kneaded using a single-screw extruder. <19> A method for producing a film according to any one of <16> to <18>, wherein the kneaded mixture is molded into a film by inflation molding. <20> The method for producing a film according to any one of <16> to <19>, wherein the second raw material further includes, as a component constituting the dispersed phase, at least one of a thermoplastic resin and a thermosetting resin having a melting point 100°C or higher than that of the first raw material. <21> The method for producing a film according to any one of <16> to <20>, wherein a corona treatment is performed on the surface of the film after film formation. <22> The method for producing a film according to any one of <16> to <21>, wherein the forming temperature is 200°C or higher and 300°C or lower. <23> The film according to any one of <1> to <15>, wherein the flat phase is oriented in the MD direction and the TD direction. <24> The film according to any one of <1> to <15> and <23>, wherein a ratio of the total cross-sectional area of ​​polyethylene to the total cross-sectional area of ​​the film in an image of the film taken with a transmission electron microscope is 60% or more. <25> The film according to any one of <1> to <15>, <23>, and <24>, wherein a ratio of a total cross-sectional area of ​​the polypropylene to a total cross-sectional area of ​​the film in an image of the film taken with a transmission electron microscope is 40% or less.<26> The film according to any one of <1> to <15> and <23> to <25>, having a polyethylene content of 50% by mass or more. <27> The film according to any one of <1> to <15> and <23> to <26>, having a polypropylene content of 50% by mass or less. <28> The film according to any one of <1> to <15> and <23> to <27>, having a ratio of the total cross-sectional area of ​​polyethylene to the total cross-sectional area of ​​the film in an image taken with a transmission electron microscope of 99% or less. <29> The film according to any one of <1> to <15> and <23> to <27>, having a ratio of the total cross-sectional area of ​​polypropylene to the total cross-sectional area of ​​the film in an image taken with a transmission electron microscope of 1% or more. <30> The film according to any one of <1> to <15> and <23> to <29>, having a polyethylene content of 99% or less. <31> The film according to any one of <1> to <15> and <23> to <30>, wherein the polypropylene content is 1% by mass or more. <32> The film according to any one of <1> to <15> and <23> to <31>, wherein the content of the resin constituting the spherical phase is 0.05% by mass or more and 20% by mass or less. <33> The film according to any one of <1> to <15> and <23> to <32>, wherein the average particle size of the spherical phase is 1 nm or more and 2 μm or less. <34> The film according to any one of <1> to <15> and <23> to <33>, wherein the spherical phase of the dispersed phase contains at least one of a styrene-based elastomer, an ethylene-α-olefin copolymer (including one in which ethylene is present as a comonomer), an olefin-based resin having a polar group introduced therein, and a styrene-based resin having a polar group introduced therein. <35> The film according to <34>, wherein the content of the resin constituting the phase, which contains at least one of a styrene-based elastomer, an ethylene-α-olefin copolymer (including those in which ethylene is present as a comonomer), an olefin-based resin having a polar group introduced therein, and a styrene-based resin having a polar group introduced therein, is 0.5% by mass or more and 15% by mass or less.<36> The film according to any one of <1> to <15> and <23> to <35>, wherein waste derived from absorbent articles is used as part of the raw materials, and wherein waste derived from absorbent articles is used as a raw material for at least the flat phase in the dispersed phase. <37> The film according to any one of <1> to <15> and <23> to <36>, wherein the film is used as a packaging film. <38> The film according to any one of <1> to <15> and <23> to <37>, wherein the glossiness of the surface of the film is 80 or less.

[0059] Examples and Comparative Examples Examples and comparative examples of the above-described embodiment will be described below, but the present invention is not limited to the configurations of the following examples.

[0060] (Raw Materials) The following linear low-density polyethylene (LLDPE) products with different melt flow rates (MFR) were used as virgin polyethylene (PE) materials constituting the first raw material. In Tables 1 to 5 below, MFRs are shown without units to distinguish between the polyethylene (PE) products. The polyethylene MFRs shown are the manufacturer catalog values ​​for each product (190°C, 2.16 kg load). Evolue SP2510 (manufactured by Prime Polymer Co., Ltd., MFR: 1.5 g / 10 min) Evolue SP2020 (manufactured by Prime Polymer Co., Ltd., MFR: 2.3 g / 10 min) Evolue SP2540 (manufactured by Prime Polymer Co., Ltd., MFR: 3.8 g / 10 min) UJ317 (manufactured by Japan Polyethylene Co., Ltd., MFR: 6.0 g / 10 min) Ultzex ​​2520F (manufactured by Prime Polymer Co., Ltd., MFR: 2.2 g / 10 min)

[0061] Recycled materials 1 and 2 were used as recycled materials primarily composed of polypropylene (PP) constituting the second raw material. Recycled material 1 was obtained by pelletizing scraps generated when cutting the crotch section during the manufacturing process of Merries (registered trademark) Pants, Smooth Air-Through, Large size (manufactured in 2022), a baby diaper manufactured by Kao Corporation, using a single-screw extruder. The average composition of recycled material 1 was 84% ​​by mass of polypropylene (PP), 4% by mass of styrene-based elastomer, and 2% by mass of polyurethane (PU). Recycled material 2 was obtained by pelletizing scraps generated when cutting the round section during the manufacturing process of Laurier (registered trademark) Shiawase Suhada, Especially Heavy Daytime, 25 cm with Wings, a sanitary napkin manufactured by Kao Corporation (manufactured in 2022), using a single-screw extruder. The average composition of the recycled material 2 is 30% by mass of polyethylene (PE), 35% by mass of polypropylene (PP), 2% by mass of polyethylene terephthalate (PET), and 28% by mass of calcium carbonate. The raw material composition of the recycled material may vary depending on the composition of the product from which it is generated, but from the perspective of film quality and reducing virgin material, it is preferable to control the blending ratio of the recycled material in the first raw material to a range of 20 to 50% by mass of PP in the film, 0 to 5% by mass of PET in the film, 0 to 5% by mass of PU in the film, and a total of 50% by mass or less of the above resins.

[0062] The following products with different melt flow rates (MFR) were used as virgin polypropylene (PP) materials constituting the second raw material. In Tables 4 and 5 below, MFRs are shown without units to distinguish between the polypropylene products. The MFRs of the polypropylenes are listed as the manufacturer's catalog values ​​(230°C, load 2.16 kg). F300SP (manufactured by Prime Polymer, MFR: 2 g / 10 min) PM600A (manufactured by SunAllomer, MFR: 7.5 g / 10 min) 3155E3 (manufactured by ExxonMobil, MFR: 36 g / 10 min) PLB00A (manufactured by SunAllomer, MFR: 70 g / 10 min) MF650Y (manufactured by LyondellBasel, MFR: 1800 g / 10 min)

[0063] TRN-RTJ (manufactured by Teijin Limited) was used as the polyethylene terephthalate (PET). Dispersing aids 1 and 2 were used as the dispersing aids. Vistamaxx Performance Polymer 7050BF (manufactured by ExxonMobil Corporation), an ethylene-propylene copolymer, was used as dispersing aid 1. Tuftec M C5025 (manufactured by Asahi Kasei Corporation), a maleic anhydride-modified hydrogenated styrene-based thermoplastic elastomer, was used as dispersing aid 2. Calcium carbonate and titanium oxide were used as inorganic materials constituting the inorganic material phase. Specifically, calcium carbonate was used, which was a re-pelletized product of production waste from the moisture-permeable film for Merries baby diapers manufactured by Kao Corporation (a blend of Ultzex ​​2520F (manufactured by Prime Polymer Co., Ltd., MFR: 2.2 g / 10 min) and calcium carbonate). As the titanium oxide, a titanium oxide master, TET1TA538WHT-FD (manufactured by Toyocolor Co., Ltd.), was used. In Tables 1 to 5 below, the content of each raw material is shown as a mass ratio.

[0064] (Analysis Method) Some of the films produced using the above raw materials were evaluated using TEM images to analyze the dispersed phase. Specifically, for each film, the total cross-sectional area ratio of the dispersed phase to the entire film (dispersed phase / entire film) was determined. In addition, for each film, the average aspect ratio of the flat phase and the total cross-sectional area ratio of the flat phase to the entire dispersed phase (flat phase / dispersed phase) were determined. Furthermore, for each film, the total cross-sectional area ratio of the spherical phase to the entire dispersed phase (spherical phase / dispersed phase) was determined.

[0065] (Evaluation Methods) The methods for measuring tensile elongation and tensile strength, the method for measuring tear strength, the method for the KES surface test, and the method for measuring glossiness are as described in the above embodiment.

[0066] (Reference Examples and Comparative Examples) As Reference Examples and Comparative Examples, films were produced using the production conditions and raw materials shown in Table 1. In both Reference Examples and Comparative Examples, a single-screw extruder was used for kneading, and inflation molding was used for molding. The film according to the Reference Example differs from the configuration of the above-described embodiments in that it is composed only of polyethylene (PE), and has a configuration that provides good quality as a general film. In other words, the film according to Comparative Example 1 serves as a standard for good quality when evaluating the films according to each Example. The film according to the Comparative Example differs from the configuration of the above-described embodiments in that the ratio ηB / ηA of the viscosity ηB of polypropylene (PP) to the viscosity ηA of polyethylene (PE) is 1 or greater. Figure 6 shows a TEM image of the MD cross section of the film according to the Comparative Example. In the film according to the Comparative Example, the average aspect ratio of the flat phase determined from the TEM image shown in Figure 6 was 12.3, which was smaller than that of the above-described embodiments.

[0067] Table 1 shows the evaluation results of the films according to the Reference Example and Comparative Example. The film according to the Comparative Example had lower tensile elongation, tensile strength, and tear strength than the film according to the Reference Example. In particular, the film according to the Comparative Example had significantly lower tensile elongation, making it difficult to use as a packaging film. Furthermore, the film according to the Comparative Example had higher MMD and SMD measured by the KES surface test than the film according to the Reference Example, and was found to have a rough texture. Accordingly, it is believed that the film according to the Comparative Example had a significantly lower gloss than the film according to the Reference Example.

[0068]

[0069] (Examples 1 to 7) In Examples 1 to 7, films were produced using the production conditions and raw materials shown in Table 2. In all of Examples 1 to 7, a single-screw extruder was used for kneading, and inflation molding was used for molding. In all of Examples 1 to 7, recycled material 1 was used as the second raw material. In all of the films according to Examples 1 to 7, the ratio ηB / ηA of the viscosity ηB of polypropylene (PP) to the viscosity ηA of polyethylene (PE) fell within the range of the above embodiment.

[0070] Figure 7 shows a TEM image of the MD cross section of the film of Example 4. In the film of Example 4, the average aspect ratio of the flat phases determined from the TEM image shown in Figure 7 was 29.5, and the average aspect ratio of the spherical phases formed of polyurethane (PU) was 1. In addition, in the film of Example 1, the average aspect ratio of the flat phases determined from the TEM image was 66.5, and the average aspect ratio of the spherical phases formed of polyurethane (PU) was 1. In both the films of Examples 1 and 4, the total cross-sectional area ratio of the flat phases to the entire dispersed phase was 80% or more.

[0071] Table 2 shows the evaluation results for the films according to Examples 1 to 7. All of the films according to Examples 1 to 7 exhibited significantly higher tensile elongation than the film according to the Comparative Example. Furthermore, the evaluation results for Examples 1 to 7 indicated a tendency for films with a smaller ratio ηB / ηA of the viscosity of polypropylene (PP) to the viscosity ηA of polyethylene (PE), to exhibit higher tensile elongation. Furthermore, all of the films according to Examples 1 to 7 exhibited lower MMD and SMD measured by the KES surface test than the film according to the Comparative Example, demonstrating a favorable feel. Additionally, all of the films according to Examples 1 to 7 exhibited a lower gloss than the film according to the Reference Example, demonstrating a matte visual texture.

[0072]

[0073] (Examples 8 to 10) In Examples 8 to 10, films were produced using the production conditions and raw materials shown in Table 3. In all of Examples 8 to 10, a single-screw extruder was used for kneading, and inflation molding was used for molding. In all of Examples 8 to 10, recycled material 1 was used as the second raw material. In Examples 8 and 9, calcium carbonate was further used as the inorganic material constituting the inorganic material phase. In Example 10, titanium oxide was further used as the inorganic material constituting the inorganic material phase. In all of the films according to Examples 8 to 10, the ratio ηB / ηA of the viscosity ηB of polypropylene (PP) to the viscosity ηA of polyethylene (PE) fell within the range of the above embodiment.

[0074] Table 3 shows the evaluation results of the films according to Examples 8 to 10. All of the films according to Examples 8 to 10 had significantly higher tensile elongation than the film according to the Comparative Example. Furthermore, all of the films according to Examples 8 to 10 had lower MMD and SMD measured by the KES surface test than the film according to the Comparative Example, indicating that they had a good feel to the touch. Furthermore, all of the films according to Examples 8 to 10 had a lower gloss than the film according to the Reference Example, indicating that they had a matte visual texture.

[0075]

[0076] (Examples 11 to 24) In Examples 11 to 24, films were produced using the production conditions and raw materials shown in Tables 4 and 5. In all of Examples 11 to 24, a single-screw extruder was used for kneading, and inflation molding was used for molding. In all of Examples 11 to 24, virgin polypropylene (PP) material was used as the second raw material. In Examples 11 to 16, the kneading temperature and molding temperature were 230°C. In Examples 17 to 21, the kneading temperature and molding temperature were 200°C. In Examples 22 to 24, polyethylene terephthalate (PET) was further used as the resin constituting the spherical phase, and the kneading temperature and molding temperature were 270°C. In all of the films according to Examples 11 to 24, the ratio ηB / ηA of the viscosity of polypropylene (PP) to the viscosity ηA of polyethylene (PE) fell within the range of the above-described embodiment. In all of Examples 22 to 24, the ratio of the viscosity of polyethylene terephthalate (PET) to the viscosity ηA of polyethylene (PE) at the molding temperature was 0.11.

[0077] FIG. 8 shows a TEM image of the MD cross section of the film according to Example 24. In the film according to Example 24, the average aspect ratio of the flat phases determined from the TEM image shown in FIG. 8 was 24.5, and the average aspect ratio of the spherical phases formed of polyethylene terephthalate (PET) was 2. In addition, in the film according to Example 17, the average aspect ratio of the flat phases determined from the TEM image was 16.5. In addition, in the film according to Example 21, the average aspect ratio of the flat phases determined from the TEM image was 52.7. In addition, in all of the films according to Examples 17, 21, and 24, the total cross-sectional area ratio of the flat phases to the entire dispersed phase was 60% or more.

[0078] Tables 4 and 5 show the evaluation results of the films of Examples 11 to 24. All of the films of Examples 11 to 24 exhibited significantly higher tensile elongation than the films of the Comparative Examples. Furthermore, comparing the evaluation results of Examples 13 and 19 with those of Examples 22 to 24, it was found that the use of polyethylene terephthalate (PET) significantly improved tear strength. Furthermore, all of the films of Examples 11 to 24 exhibited lower MMD and SMD measured by the KES surface test than the films of the Comparative Examples, demonstrating a favorable feel. Additionally, all of the films of Examples 11 to 24 exhibited lower gloss than the films of the Reference Examples, demonstrating a matte visual texture.

[0079]

[0080]

[0081] Examples 25-27 Films were produced using the manufacturing conditions and raw materials shown in Table 6 for Examples 25-27. In Example 25, a single-screw extruder was used for mixing, and inflation molding was used for molding. In Example 25, recycled material 2 was used as the second raw material. In Example 26, a single-screw extruder and a twin-screw extruder were used in combination for mixing, and inflation molding was used for molding. More specifically, in Example 26, mixing was performed using a twin-screw extruder before mixing using a single-screw extruder. In Example 26, recycled material 1 was used as the second raw material, and titanium oxide was used as the inorganic material constituting the inorganic material phase. In Example 27, a single-screw extruder was used for mixing, and T-die molding was used for molding. In Example 27, recycled material 1 was used as the second raw material. In all of the films according to Examples 25-27, the ratio ηB / ηA of the viscosity of polypropylene (PP) to the viscosity ηA of polyethylene (PE) fell within the range of the above-described embodiment.

[0082] In the film of Example 26, the average aspect ratio of the flat phase, as determined from the TEM image in the same manner as above, was 30.0, and the average aspect ratio of the spherical phase formed of polyurethane (PU) was 1. In addition, in the film of Example 26, the total cross-sectional area ratio of the flat phase to the entire dispersed phase was 80% or more.

[0083] Table 6 shows the evaluation results of the films according to Examples 25 to 27. The films according to Examples 25 to 27 all had significantly higher tensile elongation than the film according to the comparative example. Furthermore, the films according to Examples 25 to 27 all had lower MMD and SMD measured by the KES surface test than the film according to the comparative example, indicating that they had a good feel. Furthermore, the films according to Examples 25 to 27 all had a lower gloss than the film according to the reference example, indicating that they had a matte visual texture.

[0084]

[0085] According to the present invention, it is possible to suppress deterioration in quality due to polypropylene in a film in which polypropylene is dispersed in polyethylene.

Claims

1. A film having a dispersed phase dispersed in a matrix phase, the film comprising a matrix phase containing polyethylene and a dispersed phase containing polypropylene, the dispersed phase containing flat phases oriented at least in the MD direction, and the average aspect ratio of the flat phases being 15 or more.

2. The film according to claim 1, wherein the ratio of the total cross-sectional area of ​​the flat phase to the total cross-sectional area of ​​the dispersed phase in an image of the film taken with a transmission electron microscope is 60% or more.

3. The film according to claim 1 or 2, wherein the dispersed phase is composed of a resin and further contains a spherical phase having an aspect ratio of 3 or less.

4. The film according to claim 3, wherein the spherical phase comprises at least one of polyethylene terephthalate and polyurethane.

5. The film according to any one of claims 1 to 4, wherein the dispersed phase further comprises an inorganic material phase.

6. The film according to any one of claims 1 to 5, wherein the ratio of the total cross-sectional area of ​​the polyethylene to the total cross-sectional area of ​​the film in an image of the film taken with a transmission electron microscope is 50% or more and 99% or less.

7. The film according to any one of claims 1 to 6, wherein the ratio of the total cross-sectional area of ​​the polypropylene to the total cross-sectional area of ​​the film in an image of the film taken with a transmission electron microscope is 1% or more and 50% or less.

8. The film according to any one of claims 1 to 7, having a tensile elongation of 700% or more.

9. The film according to any one of claims 1 to 8, having a tensile strength of 0.23 N / (μm·cm) or more.

10. The film according to any one of claims 1 to 9, having a tear strength of 0.015 N / μm or more.

11. The film according to any one of claims 1 to 10, having an MMD of 0.05 or less according to the KES surface test.

12. The film according to any one of claims 1 to 11, having an SMD of 3.0 or less according to the KES surface test.

13. The film according to any one of claims 1 to 12, having a surface gloss of 80 or less.

14. The film according to any one of claims 1 to 13, having a surface wettability of 40 mN / m or more.

15. The film according to any one of claims 1 to 14, wherein waste materials derived from absorbent articles are used as part of the raw materials.

16. A method for producing a film having a dispersed phase dispersed in a matrix phase, comprising the steps of: kneading a first raw material containing polyethylene and constituting the matrix phase with a second raw material containing polypropylene as a component constituting the dispersed phase; forming a mixture into a film; and a ratio ηB / ηA of the viscosity ηA of the first raw material at a molding temperature during film molding to the viscosity ηB of polypropylene contained in the second raw material at the molding temperature is 0.015 or more and less than 1.

17. The method for producing a film according to claim 16, wherein the second raw material comprises waste material derived from absorbent articles.

18. The method for producing a film according to claim 16 or 17, wherein the first raw material and the second raw material are kneaded using a single screw extruder.

19. The method for producing a film according to any one of claims 16 to 18, wherein the kneaded mixture is molded into a film by inflation molding.

20. A method for producing a film described in any one of claims 16 to 19, wherein the second raw material further contains at least one of a thermoplastic resin and a thermosetting resin having a melting point 100°C or more higher than that of the first raw material as a component constituting the dispersed phase.

21. The method for producing a film according to any one of claims 16 to 20, further comprising subjecting the surface of the film after molding to a corona treatment.

22. The method for producing a film according to any one of claims 16 to 21, wherein the forming temperature is 200°C or higher and 300°C or lower.

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