Sealant Film

Abstract

To provide a sealant film that has excellent environmental adaptability and that maintains thermoadhesiveness while using a recycled polyolefin.SOLUTION: A sealant film uses a polyolefin film that includes a recycled polyolefin. The recycled polyolefin contains 1-20 mass% of a foreign substance incompatible with polyolefins; and the foreign substance has a maximum diameter of 1-2000 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sealant film containing recycled polyolefin, and further to a packaging laminate and a packaging container using the sealant film. [Background technology]

[0002] In light of the increasing importance of environmental protection in recent years, various recycling technologies have been investigated for recovering and reusing plastics from used plastic molded products, plastic waste generated during the manufacture of molded products, etc. For example, polyethylene is widely used for various purposes, and it has been proposed to use recycled polyethylene in applications such as films.

[0003] For example, Patent Document 1 proposes a method for recovering and recycling multilayer films, which is characterized by blending low-molecular-weight polyethylene with scraps of transparent multilayer films consisting of a polyethylene layer, an adhesive layer, and a nylon layer, and proposes pelletizing the recovered recycled product and using these pellets to produce film.

[0004] Furthermore, Patent Document 2 proposes a recycled film in which the content of recycled material (e.g., recycled polyethylene) relative to the entire film is 50 to 90% by mass and the content of foreign matter is 0.1 to 2% by mass, and discloses that this recycled film has a three-layer structure, with the first layer containing 50 to 90% by mass of recycled material, 0.1 to 2% by mass of foreign matter, and 2 to 4% by mass of adhesive, the second layer containing 50 to 90% by mass of recycled material and 0.1 to 2% by mass of foreign matter, and the third layer consisting of unused low-density polyethylene (LDPE).

[0005] However, in reality, films using the above-mentioned recycled polyolefins cannot be used for producing sealant films, particularly packaging bags, because the use of recycled materials causes various problems for sealant films, such as reduced thermal adhesion, reduced flavor due to odor, poor appearance due to coloration, and reduced strength. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 3-237143 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-122985 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, an object of the present invention is to provide a sealant film that uses recycled polyolefin, yet maintains thermal adhesiveness and is environmentally friendly. Another object of the present invention is to provide a sealant film which does not necessarily contain recycled polyolefin but which does not suffer from problems such as odor, discoloration or reduced strength. It is still another object of the present invention to provide a packaging laminate and a packaging container formed using the above sealant film containing recycled polyolefin. [Means for solving the problem]

[0008] According to the present invention, there is provided a sealant film using a polyolefin layer containing recycled polyolefin, characterized in that the polyolefin layer containing recycled polyolefin contains 1 to 20 mass % of foreign matter that is incompatible with polyolefin, and the foreign matter has a maximum diameter of 1 to 2000 μm.

[0009] The sealant film of the present invention preferably employs the following aspects. (1) The foreign matter is one or more selected from gel, polyester, polyamide, adhesive, and colorant derived from recycled polyolefin. (2) A polyolefin layer containing no recycled polyolefin is provided on both sides of the polyolefin layer containing recycled polyolefin. (3) The polyolefin layer containing the recycled polyolefin further contains a virgin polyolefin that is compatible with the polyolefin. (4) The recycled polyolefin and polyolefin layer are recycled polyethylene and polyethylene layers, respectively. (5) At least one of the polyolefin layers not containing recycled polyolefin contains a colorant. (6) The visible light transmittance of the sealant film is 90% or less. (7) A method for producing a sealant film, wherein the sealant film is formed by cast film formation. (8) A packaging laminate in which a substrate film is laminated on one of the polyolefin layers of the sealant film that does not contain recycled polyolefin. (9) Packaging container using the packaging laminate 。 [Effects of the Invention]

[0010] The sealant film of the present invention is preferably a sealant film in which a polyolefin layer containing recycled polyolefin is provided on both sides of the polyolefin layer containing recycled polyolefin, and thus a decrease in adhesiveness (lamination ability, heat sealability) due to recycled polyolefin can be effectively avoided. In particular, a packaging laminate can be formed by laminating a substrate film on one side of the polyolefin layer containing no recycled polyolefin using a solvent-based or solventless thermosetting adhesive or adhesive resin, and the other side of such a packaging laminate can be heat-sealed as an inner layer to form a packaging container.

[0011] Furthermore, in the sealant film of the present invention having the above-described multilayer structure, this multilayer structure can be utilized to use agents to suppress performance degradation due to the use of recycled polyolefins, such as deodorizers to avoid a decrease in flavor due to odor, colorants (forming a colored layer) to avoid poor appearance due to coloring, and modifiers to avoid a decrease in strength. In addition, by utilizing the base film laminated onto this sealant film, the puncture strength of the packaging bag can be increased, and the gas barrier properties can be improved by forming an inorganic vapor deposition film, and the appearance characteristics can be improved by forming a printed layer. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional side view showing the layer structure of a sealant film of the present invention. [Figure 2] 2 is a schematic cross-sectional side view showing an example of the layer structure of a packaging container formed using the sealant film of FIG. 1. [Figure 3] 1 is a schematic cross-sectional side view showing a layer structure including a colored layer in a sealant film of the present invention. [Figure 4] 1 is a schematic cross-sectional side view showing an example of a packaging laminate including the layer structure of the sealant film of the present invention. [Figure 5] 5 is a schematic cross-sectional side view showing an example of a layer structure of a packaging container formed using the packaging laminate of FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Sealant film> FIG. 1 is a schematic cross-sectional side view showing the layer structure of a sealant film 10 of the present invention, which has polyolefin layers 1 and 3 that do not contain recycled polyolefin on both sides of a polyolefin layer 5 that contains recycled polyolefin.

[0014] Although not limited to this, this sealant film 10 is basically used as a packaging laminate by attaching a substrate film described later, and in the final packaging container obtained, the substrate film side becomes the outer surface, and the side opposite the substrate film becomes the side that comes into contact with the contents contained in the packaging container. Therefore, in Figures 4 and 5, the side to which the substrate film is attached is designated as (outside), and the opposite side is designated as (inside).

[0015] As can be seen from Fig. 1, in the present invention, a polyolefin layer 5 containing recycled polyolefin is sandwiched as an intermediate layer between two polyolefin layers 1 and 3 that do not contain recycled polyolefin. Therefore, this sealant film 10 has a layer structure that exhibits excellent heat sealability on both the outer and inner sides.

[0016] Fig. 2 is a schematic side cross-sectional view showing an example of the layer structure of a packaging container 20 laminated with the sealant film 10 shown in Fig. 1. Here, it is shown that the polyolefin layer 3 on the inner side that does not contain recycled polyolefin is heat-sealed.

[0017] The polyolefin layers 1 and 3 that do not contain recycled polyolefins are produced using virgin polyolefins. While the polyolefin is not particularly limited as long as it has heat-sealing properties, it is preferable to use polyethylene selected from low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), and polypropylene (PP), and it is even more preferable to use polyethylene. Furthermore, a mixture of different polyolefins, such as a mixture of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), may also be used. Furthermore, the polyolefin may be derived from petroleum-derived materials, plant-derived materials, or a mixture thereof.

[0018] The recycled polyolefin contained in the intermediate polyolefin layer 5 is recovered from used polyolefin molded articles, used polyolefin laminates containing polyester, polyamide, adhesives, and colorants, or waste materials from the production of polyolefin molded articles or polyolefin laminates, and is obtained through various processes such as crushing, washing with alkali, filtration in a molten state, and extraction with an organic solvent, which is known as material recycling. Therefore, due to the fact that it has undergone these processes, the recycled polyolefin contains foreign matter that is incompatible with polyolefin. Here, the recycled polyolefin is preferably recovered from waste materials from the production of polyolefin molded articles, and more preferably recovered from waste materials from the production of laminate films.

[0019] The polyolefin layer containing recycled polyolefin contains 1 to 20% by mass of incompatible foreign matter, and the foreign matter has a maximum diameter of 1 to 2,000 μm. The content of foreign matter is preferably 1 to 15% by mass, and more preferably 1 to 10% by mass. The foreign matter refers to polyester, polyamide, adhesive, etc., and it is particularly preferable that the amount of foreign matter derived from resins such as polyester and polyamide, which account for the majority of the incompatible foreign matter, is less than 10% by mass. If the foreign matter content is less than 1% by mass, it becomes difficult to achieve the goal of achieving excellent environmental compatibility. If the foreign matter content exceeds 20% by mass, holes will occur during molding of the polyolefin layer containing recycled polyolefin, and thermal adhesion and strength will decrease, resulting in a decrease in the quality of the sealant film. Furthermore, if the maximum diameter of the foreign matter is less than 1 μm, it may be excessively burdensome to perform a process such as crushing the foreign matter to that size. If the maximum diameter exceeds 2,000 μm, unevenness will occur on the film surface, reducing flatness, and the above-mentioned holes will be more likely to occur, thereby reducing the quality of the sealant film. Here, the maximum diameter of a foreign substance means the major axis if the foreign substance shape is elliptical, and means the maximum length of each diagonal line if the foreign substance shape is polygonal.

[0020] The foreign matter incompatible with polyolefin includes all incompatible foreign matter contained in the polyolefin molded article. The foreign matter is preferably a resin, and more preferably one or more selected from gel derived from recycled polyolefin, polyester, polyamide, and adhesive. Here, the gel derived from recycled polyolefin means recycled polyolefin solidified by crosslinking or the like, which does not melt even when heated and is incompatible.

[0021] In the present invention, because the intermediate polyolefin layer 5 contains recycled polyolefin, this sealant film 10 and the packaging laminates and packaging containers made from this film 10 are also environmentally friendly, but if more recycled polyolefin than necessary is used, the amount of virgin polyolefin used will decrease accordingly, resulting in a significant deterioration in heat sealability and other physical properties. Therefore, from the perspective of avoiding such deterioration in physical properties, the recycled polyolefin content in this sealant film 10 is preferably 15 to 90 mass%, more preferably 15 to 60 mass%.

[0022] Furthermore, in order to more reliably avoid a decrease in adhesiveness, particularly heat sealability, it is preferable that when the thickness of the intermediate polyolefin layer 5 is 100 μm, the thickness of each of the outer polyolefin layers 1 and 3 is set to approximately 10 to 60 μm (10 to 60% of the thickness of the film 5).

[0023] Furthermore, the polyolefin layer 5, which is the intermediate layer, may be formed solely from recycled polyolefin, but generally, it is preferable that it also contains virgin polyolefin. This is because the sealant film 10 is formed by co-extrusion molding using such recycled polyolefin-containing pellets and virgin polyolefin pellets. For example, the recycled polyolefin content and the thickness of the outer polyolefin layers 1 and 3 described above can be adjusted. ratio It is preferable that virgin polyolefin is blended in the polyolefin layer 5 serving as the intermediate layer within a range that satisfies the above. Specifically, provided that the recycled polyolefin content and thickness ratio are satisfied, the mass ratio of recycled polyolefin to virgin polyolefin in the polyolefin layer 5 serving as the intermediate layer is preferably within a range of recycled polyolefin:virgin polyolefin = 95:5 to 25:75. Here, 50:50 is a 2-fold dilution, and 25:75 is a 4-fold dilution. Furthermore, the polyolefin constituting the polyolefin layer 5 serving as the intermediate layer may be derived from petroleum-derived materials, plant-derived materials, or a mixture thereof.

[0024] In the sealant film 10 of the present invention having the above-mentioned layer structure, each layer preferably contains a deodorant, an antioxidant, a colorant, a modifier, etc.

[0025] The deodorizing agent captures the unpleasant odors of the recycled polyolefin and prevents the flavor of the contents from being reduced due to the unpleasant odors. It may be blended into either the outer polyolefin layers 1 and 3 or the intermediate polyolefin layer 5. However, from the viewpoint of being used to capture the unpleasant odors of the recycled polyolefin and prevent the flavor of the contents from being reduced due to the unpleasant odors, it is preferable to blend it into the intermediate polyolefin layer 5 or the film corresponding to the inner polyolefin layer 3 in Figures 4 and 5 described below.

[0026] Typical examples of such deodorizing agents include silica particles such as silica gel and aluminum silicate particles such as zeolite, but MFI zeolite is preferred because of its particularly strong dispersibility in resins and deodorizing power, and in particular silica-rich MFI zeolite having a silica-alumina molar ratio (SiO2 / Al2O3 ratio) of 80 or more. Such deodorizing agents are usually preferably used in an amount of 1 to 30 parts by mass per 100 parts by mass of recycled polyolefin.

[0027] Typical antioxidants are hindered phenols and hindered amines, which have been conventionally used as resin compounding agents. Such antioxidants are used together with recycled polyolefin in the polyolefin layer 5, which is the intermediate layer, particularly to prevent further deterioration due to oxidation of the recycled polyolefin, and are usually preferably used in an amount of 0.1 to 0.3 parts by mass per 100 parts by mass of recycled polyolefin.

[0028] The colorant is used for the purposes of concealing coloring caused by recycled polyolefin, and for the printed layer or printed base layer of the packaging container. Either pigment or dye may be used, but pigment is preferred due to its excellent weather resistance and durability. The type of colorant is not particularly limited as long as it achieves the above-mentioned purpose, but white pigments are preferred in consideration of the printed base layer of the packaging container. Typical white pigments include titanium oxide, zinc oxide, calcium carbonate, etc. The colorant may be contained in at least one of the outer polyolefin layers 1 and 3. Regarding color density, an appropriate amount is used in consideration of concealing the coloring, but the visible light transmittance at 380 to 800 nm is preferably 90% or less, and more preferably 60% or less.

[0029] Modifiers are used to suppress the decrease in strength due to factors such as a decrease in the molecular weight of recycled polyolefins, and are typically blended into the polyolefin layer 5, which is the intermediate layer containing recycled polyolefins. Thermoplastic elastomers are preferably used as such modifiers. Specifically, they improve impact resistance by imparting elasticity to the polyolefin layer 5, which is the intermediate layer. Examples of such thermoplastic elastomers include ethylene-α-olefin copolymers, ethylene-propylene copolymers (EPR), styrene-butadiene copolymers (SBR), and ethylene-propylene-butene copolymers (EPBR). Ethylene-α-olefin copolymers are particularly preferred due to their excellent dispersibility in polyolefins. The modifier is preferably blended in the polyolefin layer 5, which is the intermediate layer, in an amount of 1 to 30 parts by mass per 100 parts by mass of recycled polyolefin. Furthermore, since recycled polyolefin contains the above-mentioned polyesters, polyamides, adhesives, and colorants, an ester decomposition inhibitor such as a carbodiimide compound may be added to suppress a decrease in strength due to a decrease in molecular weight of these materials, and a compatibilizer may be added to improve dispersibility. Examples of polar groups in the compatibilizer include organic isocyanate groups, carboxylic acid anhydride groups, carboxylic acid groups, amino groups, hydroxyl groups, epoxy groups, and acrylate groups, and acid-modified olefin resins, imine-modified olefin resins, and acrylate-glycidyl methacrylate copolymerized olefin resins are preferred. Other additives that may be added include lubricants, ultraviolet absorbers, plasticizers, crystal nucleating agents, fillers, hydrolysis inhibitors, flame retardants, antistatic agents, anti-fogging agents, and anti-blocking agents, as long as they do not impair the physical properties.

[0030] The sealant film 10 of the present invention can be embodied in various forms, provided that it has the basic three-layer structure described above. For example, by incorporating a colorant into the outer polyolefin layer 1 in Fig. 2 to form a colored layer, the coloring caused by the recycled polyolefin can be concealed from the outside, and at the same time, by incorporating a deodorizing agent into the inner polyolefin layer 3 to capture the odor caused by the recycled polyolefin, deterioration of the flavor of the contents of the packaging container can be prevented.

[0031] Furthermore, the colored layer and the layer containing the deodorant may be provided as independent layers.

[0032] Fig. 3 is a schematic side cross-sectional view showing the five-layer structure of a sealant film 11 in which a colored layer 7 is provided as an independent layer between the polyolefin layer 5 containing recycled polyolefin and the polyolefin layers 1 and 3 not containing recycled polyolefin in the sealant film 10 shown in Fig. 1. The colored layer 7 is made of virgin polyolefin to which a colorant has been blended. In this five-layer sealant film 11, as in the sealant film 10, it is desirable to maintain the recycled polyolefin content within the aforementioned range (15 to 90 mass%).

[0033] The thickness of the sealant film 10 of the present invention is not particularly limited, but in consideration of the rigidity when used as a packaging container, it is usually preferably in the range of about 50 to 200 μm.

[0034] The sealant film 10 of the present invention is produced by cast film production, in which the components are dry-blended and fed into an extruder for melt-kneading. The blend is then co-extruded into a film form through a T-die, and the extruded molten multilayer film is brought into contact with a cooling roll to solidify and then wound up. The components may be fed in the form of film-like fragments, pellets, granules, or liquid. The film-like fragments may be film scraps generated during the implementation of the present invention. In inflation molding, which is typically used to extrude a bag-shaped film for sealant film production, the presence of incompatible foreign matter in the polyolefin tends to result in holes and thickness variations. Passing the film through a fine-mesh filter to remove the foreign matter significantly reduces production speed. In contrast, cast film production makes it easy to obtain high-quality films without holes and with minimal thickness variations. Since there is no need to pass the film through a fine-mesh filter, production speed reductions can be suppressed.

[0035] <Packaging laminate> The sealant film 10 of the present invention described above can be used for various purposes by taking advantage of the good adhesive properties of the virgin polyolefin layers 1 and 3 present on both sides thereof, but is particularly suitable for use as a packaging laminate for producing packaging containers.

[0036] Figure 4 is a schematic side cross-sectional view showing the layer structure of a packaging laminate 30, which has a base film 21 laminated on a polyolefin layer 1 that does not contain recycled polyolefin in a sealant film 10, and in which a functional layer 23 is formed, as needed, between the base film 21 and the polyolefin layer 1.

[0037] The above-mentioned base film 21 is provided so as to be positioned on the outer surface side of the packaging container, and its material is not particularly limited, but polyethylene resin, polypropylene resin, polyamide resin, polyester resin, polyvinyl alcohol resin, etc. are suitable in that they provide appropriate rigidity when used as a packaging container. Examples of the polyethylene resin include high density polyethylene, medium density polyethylene, low density polyethylene, and linear low density polyethylene. Examples of the polypropylene resin include homopolypropylene and block polypropylene. Pi Examples of the polyamide resin include nylon 6, nylon 6-6, nylon 6-10, nylon 11, nylon 12, nylon 13, nylon 6 / nylon 6,6 copolymer, aromatic nylon (e.g., polymetaxylylene adipamide), and amorphous nylon (e.g., nylon 6I / 6T). Examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate (PEN). Polyamide films and polyester films are suitable for increasing the puncture strength of packaging bags. Polyvinyl alcohol resins are suitable for improving gas barrier performance, and ethylene-vinyl alcohol copolymers with an ethylene content of 20 to 50 mol% are particularly suitable. The base film 21 may be stretched or laminated without being stretched. The material constituting the base film 21 may be derived from petroleum-derived materials, plant-derived materials, or a mixture thereof. It may also contain recycled material or chemically recycled material. The thickness of such a substrate film 21 is usually about 5 to 50 μm.

[0038] Furthermore, the functional layer 23 that is formed as needed is typically an inorganic vapor deposition layer or a printed layer.

[0039] The inorganic vapor deposition layer is formed by plasma CVD using aluminum, aluminum compounds, silicon compounds, etc., and is used to improve the gas barrier properties of the packaging bag and to conceal coloration caused by recycled polyolefin. Such an inorganic vapor deposition layer is a thin layer with a thickness of about 0.001 to 1 μm. To further improve gas barrier performance, the thin layer may contain a coating film formed by a crosslinking reaction between carboxylic acid and metal, or a coating film in which metal oxide is dispersed.

[0040] The printing layer is formed with ink of each color by gravure printing, flexographic printing, offset printing, inkjet printing, etc., and is intended for decoration, etc., but in the case of solid printing in particular, it also has the effect and function of concealing coloration caused by the recycled polyolefin. Furthermore, by using it in combination with the colored layer 7 in FIG. 3, a more sophisticated and complicated decorative print layer can be obtained. The thickness of such a printing layer is usually 10 μm or less.

[0041] Such a packaging laminate 30 can also be produced by providing a functional layer such as an inorganic vapor deposition layer or a printed layer on the surface of the base film 21, and then using a thermosetting adhesive such as a urethane adhesive or an epoxy adhesive to attach the base film 21 (or the functional layer 23) to the polyolefin layer 1 of the sealant film 10. Alternatively, it may be produced by attaching the base film 21 (or the functional layer 23) to the polyolefin layer 1 of the sealant film 10 by extrusion coating using an adhesive resin.

[0042] <Packaging container> FIG. 5 is a schematic side cross-sectional view showing an example of the layer structure of a packaging container 40 in which the above-mentioned packaging laminate 30 is cut to an appropriate size and then bonded by heat sealing between the polyolefin layers 3 located on the inner side of FIG. 4.

[0043] Bonding by heat sealing is performed by known means. For example, an empty pouch is made by sealing two laminates 30 on three sides, and contents are filled through the opening. Finally, the opening is closed by heat sealing to obtain a packaging container (pouch) 40 filled with contents. Alternatively, one laminate 30 can be formed into a cylindrical shape and the polyolefin layers 3 at both ends are heat sealed to make the body of the pouch, and then a bottom having a special shape can be made by heat sealing to produce an empty pouch. Such a method is advantageous for increasing the volume of the pouch or imparting standing properties.

[0044] Furthermore, it is preferable to manufacture a packaging container 40 by using the packaging laminate 30 of the present invention exclusively for the body and a conventional sealant film made of virgin polyolefin exclusively for the bottom. The packaging container 40 obtained in this manner has a high strength bottom and is therefore particularly suitable for use as a stand-up pouch. The standing pouch may have a three-dimensionally molded spout, or a spout may be attached as the spout. [Example]

[0045] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0046] Table 1 shows the types of base film, sealant film, and adhesive for the four types of laminate films 1 to 4 used as recycled polyolefin. Here, PE, PA, PET, VM-PET, and LLDPE stand for polyethylene, polyamide, polyethylene terephthalate, aluminum-vapor-deposited polyethylene terephthalate, and linear low-density polyethylene, respectively.

[0047] [Table 1]

[0048] Each of the recovered laminate films 1 to 4 was flaked using a crusher (VC-360 manufactured by HORAI Co., Ltd.), and the flakes were then extruded using a twin-screw extruder equipped with a granulation facility (TEM-35B manufactured by Toshiba Machine Co., Ltd.) at a barrel temperature of 240°C and a screw rotation speed of 200 rpm. The extruded strands were air-cooled and then pelletized to obtain pellets.

[0049] As virgin polyolefin, "linear low-density polyethylene (density: 0.915 g / cm 3 ) / Low density polyethylene (density: 0.919 g / cm 3 ) = 70 / 30, and when the flake-derived pellets were fed into the twin-screw extruder, the recycled polyolefin was diluted as needed.

[0050] The pellets were melt-kneaded using a single-screw extruder and a film-forming machine equipped with a T-die (manufactured by Toyo Seiki Seisakusho, Ltd.), extruded into a film form from the T-die, and wound up on a cooling roll at 60°C to form a film with a thickness of 90 μm, thereby obtaining polyolefin films containing recycled polyolefin in Examples 1 to 4 and Comparative Examples 1 to 3. Here, visual observation of foreign matter was performed using a 20x microscope, and it was confirmed that no foreign matter with a maximum diameter greater than 2000 μm (2 mm) was present.

[0051] Table 2 shows the type of recycled polyolefin used, the dilution ratio with virgin polyethylene, the type of foreign matter, the content of foreign matter, and the presence or absence of holes in the film for the polyolefin films of Examples 1 to 4 and Comparative Examples 1 to 3. Here, the content of polyester, polyamide, and adhesive as foreign matter was calculated from the charging ratio during the production of the film.

[0052] [Table 2]

[0053] The polyolefin films of Examples 1 to 4 contained polyethylene terephthalate, polyamide, and adhesive as foreign matter, with a total content of 4 to 12 mass% of these foreign matters, and no holes were formed in the films. However, the polyolefin films of Comparative Examples 1 to 3 contained a total content of 22 to 24 mass% of foreign matters, and holes were formed in the films due to the foreign matters.

[0054] Table 2 lists polyethylene-derived gel and aluminum as types of foreign matter, but because both were present in trace amounts of less than 0.5% by mass, it was determined that they would not have a significant impact on the physical properties of the film, such as holes, and therefore the content was not shown.

[0055] In Examples 5 to 8, sealant films (thicknesses: 30 μm / 90 μm / 30 μm) were produced, each consisting of three layers: a middle polyolefin layer made from the polyolefin films of Examples 1 to 4, and a polyolefin film on each side made from virgin polyethylene blended with 10% by mass of titanium oxide. The visible light transmittance (%) of 380 to 780 nm measured using an ultraviolet-visible-near-infrared spectrophotometer (Shimadzu UV-3600) was 24%, and no foreign matter was visually observed inside each sealant film, confirming that the appearance was good. It was also confirmed that each sealant film could be used to produce packaging containers. [Industrial Applicability]

[0056] Packaging containers obtained from the sealant film of the present invention contain a large amount of recycled polyolefin, and are not only environmentally friendly but also effectively avoid performance degradation due to the recycled polyolefin, and are useful as packaging containers for containing liquid or solid substances, particularly foods, liquid detergents, shampoos, conditioners, etc. They are particularly suitable for use as standing pouches for refilling shampoos, conditioners, etc. [Explanation of symbols]

[0057] 1: Polyolefin layer containing no recycled polyolefin Polyolefin layer not containing recycled polyolefin on the opposite side of 1 in a 3:5 ratio 5: Polyolefin layer containing recycled polyolefin 7: Colored layer 10: Sealant film 21: Base film 23: Functional layer 30: Packaging laminate 40: Packaging container

Claims

1. A sealant film using a polyolefin layer containing recycled polyolefin, wherein the polyolefin layer containing recycled polyolefin contains 1 to 20 mass % of foreign matter that is incompatible with polyolefin, and the foreign matter has a maximum diameter of 1 to 2000 μm, and polyolefin layers that do not contain recycled polyolefin are provided on both sides of the polyolefin layer containing recycled polyolefin, and the polyolefin layers containing recycled polyolefin further contain virgin polyolefin that is compatible with polyolefin.

2. The sealant film according to claim 1, wherein the foreign matter is at least one selected from the group consisting of gel derived from recycled polyolefin, polyester, polyamide, adhesive, and colorant.

3. 2. The sealant film according to claim 1, wherein the recycled polyolefin and polyolefin layer are recycled polyethylene and polyethylene layers, respectively.

4. The sealant film of claim 1 , wherein at least one of the polyolefin layers that does not contain recycled polyolefin contains a colorant.

5. 2. The sealant film according to claim 1, which has a visible light transmittance of 90% or less.

6. The method for producing the sealant film according to claim 1, wherein the sealant film is formed by cast film formation.

7. 2. A packaging laminate comprising the sealant film according to claim 1, and a substrate film laminated on one of the polyolefin layers not containing recycled polyolefin.

8. A packaging container using the packaging laminate according to claim 7.

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