Container, liquid holding body, ink tank, and ink jet printer

Abstract

To provide a container, even when recycled resins containing metal soaps are used as materials, which can suppress an influence on the properties of contents by the metal soaps contained in the recycled resins.SOLUTION: Disclosed is a container having a multi-layered resin molded body. The multi-layered resin molded body contains a first resin layer and a second resin layer located at the inside of the container compared to the first resin layer. A resin composition composing the second resin layer contains a polyolefin resin, and at least in a part of a region where the first resin layer and the second resin layer are superimposed, the thickness of the second resin layer is smaller than the thickness of the first resin layer, and the concentration of a metal soap in the second resin layer is lower than the concentration of a metal soap in the first resin layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a container, a liquid holder, an ink tank, and an inkjet printer. [Background technology]

[0002] In recent years, with the increasing demand for reducing environmental impact, there has been a demand for a shift to recycled resins for the resin materials used to form containers for liquid storage containers, such as ink cartridges and ink tanks for inkjet printers.

[0003] Patent Document 1 discloses a liquid storage container and ink tank made of a resin-containing material and capable of storing liquid. The document describes a method for manufacturing the container, which includes used resin, and a method for improving the molecular weight of the used resin by adding a Ziegler-Natta catalyst, a metallocene catalyst, and a dehydration condensation agent to the used resin during the resin melting process. The method is characterized by the fact that this method prevents the container from losing strength and physical properties and from becoming discolored. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-171645 Summary of the Invention [Problem to be solved by the invention]

[0005] The container may affect the properties of the contents of the container. Patent Document 1 does not mention the effect of the container on the contents. [Means for solving the problem]

[0006] An object of one aspect of the present disclosure is to provide a container that can suppress the influence on the properties of the contents.

[0007] One aspect of the present disclosure is a container having a multilayer resin molded body, the multilayer resin molded body including a first resin layer and a second resin layer located inside the container relative to the first resin layer, the resin composition constituting the second resin layer including a polyolefin resin, and in at least a portion of the region where the first resin layer and the second resin layer overlap, the thickness of the second resin layer is smaller than the thickness of the first resin layer, and the concentration of metal soap in the second resin layer is lower than the concentration of metal soap in the first resin layer. [Effects of the Invention]

[0008] According to one aspect of the present disclosure, a container can be provided that can suppress the impact on the properties of the contents. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating one embodiment of a container according to the present disclosure. [Figure 2] 1 is a schematic diagram illustrating one embodiment of a container according to the present disclosure. [Figure 3] 1 is a graph showing the relationship between the metal soap concentration difference and the adhesive strength for the multilayer resin molded body according to the example. [Figure 4] 1A to 1C are diagrams showing an example of manufacturing a container by direct blow molding. [Figure 5] FIG. 1 is a schematic diagram showing a rectangular container according to an embodiment. [Figure 6] 1 is a schematic diagram illustrating one embodiment of a container according to the present disclosure. [Figure 7] 1 is a schematic diagram illustrating an embodiment of an inkjet printer equipped with a reservoir according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, similar or corresponding elements are denoted by the same reference numerals, and their description may be omitted or simplified.

[0011] Figure 1 is a schematic diagram showing one embodiment of a container according to the present disclosure, in which Figure 1(a) is a perspective view of the container, and Figure 1(b) is a cross-sectional view of the container shown in Figure 1(a) taken along the AA axis.

[0012] The container according to the present disclosure is a container having a multilayer resin molded body, the multilayer resin molded body including a first resin layer and a second resin layer located inside the container relative to the first resin layer, and characterized in that the concentration of metal soap in the second resin layer is lower than the concentration of metal soap in the first resin layer.

[0013] To improve the storage characteristics of the storage container, a barrier layer is provided by multi-layer molding, which can prevent the permeation of oxygen contained in the air, which causes oxidation, and the elution of pharmacological ingredients, etc.

[0014] In multi-layer molded containers, the required role of the barrier layer differs depending on whether it is provided on the outermost or intermediate layer or on the innermost layer that comes into contact with the contents. From the viewpoint of preserving the contents, the barrier layer may be provided at any position as long as it can prevent the permeation and elution of the target substance to be blocked. For the purpose of preventing reaction between the contents and the structural material, it is preferable to provide the barrier layer on the innermost layer that comes into direct contact with the contents.

[0015] The container 100 of this embodiment shown in FIG. 1 has a body 105 for containing contents surrounded by a second resin layer 101 as the innermost layer, and also has a first resin layer 102 as a layer welded adjacent to the second resin layer 101. The first resin layer 102 can be provided so as to be exposed to the outside of the container 100. Specifically, the first resin layer 102 can be provided so as to be exposed to the outside of the container 100 in at least one of the mouth, which is a structural part constituting an opening 103 described below, the body 105, and a bottom, which can be provided on the opposite side of the body 105 from the mouth. The first resin layer 102 may be the outermost layer, or the container 100 may have a three-layer or greater structure including a layer positioned further outside the first resin layer 102. Furthermore, in at least one of the mouth, the body 105, and the bottom, the first resin layer 102 may be the outermost layer in at least a part of the region where the first resin layer 102 and the second resin layer 101 overlap. A label for the container 100 may be wrapped around or attached to the outside of the first resin layer 102, or the first resin layer 102 may be printed. Furthermore, in this embodiment, the second resin layer 101 is disposed so as to come into contact with the contents of the container 100.

[0016] As a container for storing and supplying the contents, container 100 preferably has opening 103 serving as an inlet and outlet for the contents of container 100. In this case, second resin layer 101 extending from body 105 to opening 103 serves as a portion that can come into contact with the contents. In container 100, the concentration of the metal soap contained in second resin layer 101 is lower than the concentration of the metal soap contained in first resin layer 102.

[0017] Metal soap is a general term for salts of fatty acids with metals other than sodium and potassium. They are compounds that are widely used in resin additives as release agents, lubricants, blocking agents, colorants, filler dispersants, anti-smudge agents, flow improvers, water repellents, and acid neutralizers.

[0018] The metal soap contained in the first resin layer 102 and the metal soap contained in the second resin layer 101 may contain, for example, a compound represented by the following formula (1). (C n H 2n+1 COO)2·M (1) (In formula (1), n ​​is an integer of 7 or more and 20 or less, and M represents an alkaline earth metal atom or a zinc atom.)

[0019] In particular, the metal soap contained in the second resin layer may be a fatty acid salt of calcium, or a salt of stearic acid.

[0020] Fatty acids tend to bleed easily from the material and are poorly soluble in water or organic solvents. If the contents of the container contain a liquid containing ions such as sodium, an ion exchange reaction may occur between the liquid containing ions and the fatty acid metal salt, resulting in the formation of aggregates and altering the flow properties of the contents.

[0021] For example, if the contents of the container are ink for an inkjet printer, metal soaps containing compounds where M in formula (1) is a calcium atom are particularly likely to form fibrous aggregates. The formation of these aggregates can change the ink's wettability, reducing the accuracy of the ink's landing and clogging the ink flow path, resulting in a decline in ink performance. Furthermore, metal soaps containing stearates (where n = 17 in formula (1)) are particularly prone to aggregation due to ion exchange reactions. While the reason for this is unclear, it is thought that the influence of medium-chain fatty acids is particularly significant due to the balance between affinity with the resin, solubility in the liquid, and the stability of the micelle structure in the liquid.

[0022] The difference between the metal soap concentration in the first resin layer 102 and the metal soap concentration in the second resin layer 101 can be 0.01 mass% pt or more. Furthermore, the difference between the metal soap concentration in the first resin layer 102 and the metal soap concentration in the second resin layer 101 is preferably 2.0 mass% pt or less, and more preferably less than 1.0 mass% pt.

[0023] Methods for forming a multilayer resin molded body generally include multilayer extrusion, multilayer blow molding, multilayer injection molding, and insert molding. All of these methods require welding multiple resin materials together. Metal soaps act as release agents in resins and tend to localize in the surface layers. Therefore, to increase the welding strength by aligning the electrical polarities between the surfaces of the resin layers that are bonded together, it is preferable to minimize the difference in metal soap concentration between the resin layers that are bonded together. From this perspective, in this embodiment, it is preferable that the difference in metal soap concentration between the first resin layer 102 and the second resin layer 101 be 2.0% by mass or less. In this embodiment, by maintaining the difference in metal soap concentration between the first resin layer 102 and the second resin layer 101 to 2.0% by mass or less, the adhesion strength between the first resin layer 102 and the second resin layer 101 is improved. This allows for a container in which delamination in the multilayer resin molded body is suppressed.

[0024] In order to improve adhesion strength, it is preferable that the difference in thermal expansion coefficient between the resin composition constituting the first resin layer 102 and the resin composition constituting the second resin layer 101 is small. Specifically, at least at a certain temperature in the range of 20°C to 80°C, and preferably at all temperatures in the range of 20°C to 80°C, the difference is as follows: That is, the difference in linear expansion coefficient between the resin composition constituting the first resin layer 102 and the resin composition constituting the second resin layer 101 is preferably 10 ppm / °C or less, and may be 5 ppm / °C or less.

[0025] It is particularly preferable to use virgin material for the second resin layer 101 and recycled material for the first resin layer 102. The concentration of metal soap contained in the second resin layer 101 is preferably sufficiently low to reduce the effect on the contents. Specifically, the concentration of metal soap in the second resin layer 101 is preferably less than 0.01% by mass (less than 100 ppm).

[0026] On the other hand, when the first resin layer 102 made of recycled material is used as the outermost layer, the first resin layer 102 may be colored to shield the contents from external light or to improve the appearance of the recycled material. In this case, a metal soap may be added as a dispersant for the colorant. Even when the first resin layer 102 made of recycled material is not used as the outermost layer, a metal soap may be added to the recycled material to suppress resin degradation during the recycling process and to neutralize acids caused by the inclusion of impurities. For these reasons, the concentration of the metal soap contained in the first resin layer 102 is preferably 0.01% by mass or more, and more preferably 0.02% by mass or more, depending on the type of colorant and the concentration of impurities. Furthermore, the concentration of the metal soap in the first resin layer 102 is preferably 2.0% by mass or less.

[0027] The resin composition constituting the second resin layer 101 preferably contains a polyolefin resin. The resin composition constituting the first resin layer 102 preferably contains a polyolefin resin. Polyolefin resins are chemically stable and have a good balance of physical properties such as chemical resistance to the contents, moldability, and impact resistance. In particular, when the contents is ink for an inkjet printer or the like, a resin composition containing a polyolefin resin can be suitably used as the material for the first resin layer 102 and the second resin layer 101.

[0028] Examples of polyolefin resins include homopolypropylene (homoPP), ethylene-propylene random copolymer (random copolymer PP), a mixture of ethylene-propylene-diene copolymer rubber (EPDM) and ethylene-propylene copolymer (block copolymer PP), a copolymer of propylene and an unsaturated olefin having 2 to 8 carbon atoms such as ethylene or butene, high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), very low-density polyethylene (VLDPE), ultra-high molecular weight polyethylene (UHMWPE), and cyclic polyolefin (COP) and its copolymer (COC). The polyolefin resin may also be a mixture thereof.

[0029] In particular, from the viewpoint of chemical stability against the contents, the resin composition constituting the second resin layer 101 preferably contains a polymer of an ethylene monomer or a polymer of a propylene monomer among polyolefin resins. Furthermore, the content of the polymer of an ethylene monomer or the polymer of a propylene monomer in the resin composition constituting the second resin layer 101 is preferably 50 mass % or more.

[0030] On the other hand, the resin composition constituting the first resin layer 102 is not particularly limited in terms of its relationship with the contents, but the following can be considered from the viewpoint of weldability with the second resin layer 101. That is, non-olefin resins do not have good weldability with polyolefin resins. Therefore, when the resin composition constituting the second resin layer 101 contains a polyolefin resin, the resin composition constituting the first resin layer 102 preferably contains a polymer of an ethylene monomer or a polymer of a propylene monomer in a proportion of 50% by mass or more.

[0031] The material containing 50% by mass or more of the above-mentioned ethylene monomer polymer or propylene monomer polymer is not particularly limited, but commercially available products include the following: "UBE Polyethylene (registered trademark)" manufactured by Ube Polyethylene Co., Ltd., "Suntech (registered trademark)" series manufactured by Asahi Kasei Corporation, "Sumikathen (registered trademark)" series manufactured by Sumitomo Chemical Co., Ltd., "Flothane (registered trademark)" manufactured by Sumitomo Seika Chemicals Co., Ltd., "Petrothen (registered trademark)" series manufactured by Tosoh Corporation, "Novatec (product name)" series manufactured by Japan Polyethylene Co., Ltd., "Hi-Zex (registered trademark)" series, "Neozex (registered trademark)" series, "Ultozex (registered trademark)" series, "Evolue (registered trademark)" series, and "Pla-Zex (registered trademark)" series manufactured by Prime Polymer Co., Ltd. "Impolypro (registered trademark)" series, "KEIYO Polyethylene (registered trademark)" manufactured by Keiyo Polyethylene Co., Ltd., "Sumitomo Noblen (registered trademark)" series manufactured by Sumitomo Chemical Co., Ltd., "Novatec (registered trademark)" series, "Wintech (registered trademark)" series, "Waymax (registered trademark)" series manufactured by Japan Polypropylene Corporation, "Sunallomer (registered trademark)" series, "Qualia (registered trademark)" series manufactured by Sunallomer Co., Ltd., "Daicel PP (product name)" series manufactured by Daicel Miraize Co., Ltd., and "CALP (registered trademark)" series manufactured by Idemitsu Fine Composites.

[0032] The resin composition constituting the second resin layer 101 and the resin composition constituting the first resin layer 102 do not need to contain virgin materials, and may contain resin materials collected and recycled by various home appliance manufacturers, printer manufacturers, and recycling companies. They may also contain biomass plastics derived from natural materials or materials produced by microorganisms. Furthermore, resin materials with any recycled content may be used by kneading them with the same type of virgin material.

[0033] Recycled resins are affected by processes such as washing in the mechanical recycling process, refining and chemical reactions in the chemical recycling process, and the addition of colorant dispersants in the toning process, resulting in unintended variations in the content of resin additives compared to the original material. Metal soaps (fatty acid metal salts) are a typical example of resin additives. When recycled resins are used in storage containers, particularly in components that come into contact with ink in inkjet printers, there is concern that the metal soaps in the components may leach into the contents, affecting the wettability of the contents. At the same time, there is concern that ion exchange reactions between the fatty acid metal salts and the cations in the contents may produce aggregates, altering the flow properties of the contents. Therefore, even when recycled resins containing metal soaps are used as materials, it is effective to prevent the metal soaps contained in the recycled resin from affecting the properties of the container's contents. This embodiment can provide a container that can suppress the impact of the metal soap contained in the recycled resin on the properties of the contents, even when recycled resin containing metal soap is used as the material.

[0034] The container according to the present disclosure may be optically transparent so that the amount of contents can be confirmed. In this case, the resin material of the first resin layer 102 and the second resin layer 101 may be an optically transparent resin.

[0035] Recycled materials may contain resins that are not eligible for recycling during the recycling process, but they can still be used as resin materials. There are no limitations on the types of resins that may be included other than polyolefin resins, including polystyrene-based resins such as high-impact polystyrene (HIPS), ABS resin, polyester resins such as polyethylene terephthalate (PET), polycarbonate resins and alloys of the aforementioned resins, polyacetal resin, polyphenylene ether resin, acrylic resin, polyamide resin, polylactic acid, polyvinyl chloride resin, fluororesin, and silicone resin. The use of these biomass plastics and recycled materials is preferable from the perspective of reducing environmental impact. The proportion of halogen-containing compounds in the overall material is preferably 1% by mass or less, and it is even more preferable that they are not included at all. Biomass plastics and recycled materials are particularly suitable for use in the resin composition that constitutes the first resin layer 102, which does not come into contact with the contents. The concentration of a specific resin component contained in at least one of the resin composition constituting the second resin layer 101 and the resin composition constituting the first resin layer 102 may be different between the resin composition constituting the second resin layer 101 and the resin composition constituting the first resin layer 102. The specific resin component may be a resin that may be contained in addition to the above-mentioned polyolefin resin.

[0036] In order to improve the performance of virgin or recycled materials or to restore the performance of recycled materials, one or more additives other than metal soap may be blended into the resin composition constituting the first resin layer 102 or the second resin layer 101. Specific examples of additives other than metal soap include colorants, flame retardants such as organic phosphorus compounds, elastic components such as wax, rubber, and elastomers, molding aids, sliding improvers, and anti-drip agents such as fluororesins typified by polytetrafluoroethylene (PTFE), silicone compounds, and polysiloxanes, crystal nucleating agents such as organic sodium salts and talc, various antioxidants for improving long-term stability, and ultraviolet absorbers.

[0037] Among these, PTFE improves the drawdown properties of low-viscosity materials and is suitable as a molding processing agent. The use of PTFE is expected to improve the molding processability of recycled materials with reduced molecular weight and promote the crystallization of polyolefin resins, thereby reducing the linear expansion coefficient, thereby improving the adhesion of multilayer resin molded products. Therefore, for example, the resin composition constituting the second resin layer may contain polytetrafluoroethylene and a polytetrafluoroethylene derivative.

[0038] The content of PTFE in the resin composition can be set so as to obtain such an effect. Specifically, the content of PTFE in the resin composition is preferably 0.6% by mass or more and 1% by mass or less in terms of PTFE, while keeping the difference in linear expansion coefficient between layers close enough (10 ppm / °C or less) and taking into consideration the amount of PTFE in the halogen-containing compound in the entire material.

[0039] Commercially available PTFE additives that can be used in resin applications include the following: Mitsubishi Chemical Corporation's "Metablen (registered trademark) A series," Daikin Corporation's "Polyflon (product name)" series, AGC Corporation's "Fluon (registered trademark)" series, 3M Corporation's "Dyonin (trademark) Micropowder" series, and Mitsui-Chemours Fluoro Products' low molecular weight PTFE "TLP 10F (product name)" and "MP-1300 (product name)."

[0040] Particularly when using recycled materials, some of the recovered products may contain colored products, including various dyes used in polyester fibers (azo, anthraquinone, condensation, etc.); azo pigments; phthalocyanine pigments; black pigments such as carbon black; composite metal oxide pigments such as iron, copper, cobalt, zinc, and manganese; and their dispersants. Among these, pigment dispersants may contain metal soaps. The concentrations of specific inorganic materials contained in at least one of the resin compositions constituting the second resin layer 101 and the first resin layer 102 may differ between the resin compositions constituting the second resin layer 101 and the resin compositions constituting the first resin layer 102. The specific inorganic material may be an additive other than the metal soaps described above.

[0041] Furthermore, the resin composition constituting the first resin layer 102 or the second resin layer 101 may contain inorganic fillers such as metal oxides, metal hydroxides, carbonates, sulfates, silicate compounds, glass-based fillers in various forms such as beads, flakes, balloons, fibers, and wool, silicate compounds, metal powders, metal fibers, carbon fibers, and carbon nanotubes to improve mechanical properties. Naturally-derived components such as crushed shells discarded after consumption of chicken eggs or scallops, chitin-chitosan extracted from crustacean shells, and cellulose extracted from bamboo and wood can also be used as fillers. Organic resins such as high-melting-point polyester and polyphenylene ether fibers can also be used as fillers, and these fibers may be recycled materials.

[0042] In particular, fibrous materials such as glass fiber, carbon fiber, and cellulose have a high reinforcing effect on mechanical properties such as elastic modulus, and at the same time, have a high effect on improving moldability. Therefore, for example, the resin composition constituting the second resin layer may contain a fibrous filler.

[0043] The surface of these fillers may be treated with various surface treatment agents such as silane coupling agents, titanium coupling agents, organic fatty acids, alcohols, and amines, waxes, silicone resins, and the like.

[0044] The thicknesses of the second resin layer 101 and the first resin layer 102 can be set according to the strength of the container. Considering the migration of metal soap between layers, the thickness of the second resin layer 101 is preferably 0.01 mm or more, more preferably 0.1 mm or more. Furthermore, since the cooling time required during molding increases as the resin layer thickness increases, a thickness of 3 mm or less is preferable in consideration of productivity. Therefore, the thickness of the second resin layer 101 is preferably 0.01 mm or more and 3 mm or less. Furthermore, the thickness of the first resin layer 102 is preferably 0.05 mm or more and 5 mm or less. By setting the thickness to this range, the container will have an excellent balance between impact resistance and container capacity / weight. The thickness of the first resin layer 102 may be, for example, 0.5 mm or more and 5 mm or less.

[0045] The ratio of the thickness of the second resin layer 101 to the thickness of the first resin layer 102 will now be described. It is preferable that the thickness of the second resin layer 101 is smaller than the thickness of the first resin layer 102 in at least a part of the region where the first resin layer 102 and the second resin layer 101 overlap. This increases the effect of having a relatively large amount of metal soap in the first resin layer 102, and also increases the effect of having a relatively small amount of metal soap in the second resin layer 101. This is advantageous in achieving both good performance as a container and reduced impact on the properties of the contents.

[0046] When a container is formed by blow molding, the thickness of the container varies depending on the shape and the extensibility of the material. Therefore, taking into account this variation, the ratio of the thickness of the second resin layer 101 to the thickness of the first resin layer 102 is preferably within a range of 1:100 to 1:1 (second resin layer 101:first resin layer 102), with the second resin layer 101 being thinner on the inner side of the container where deformation is less. Furthermore, the ratio of the thickness of the second resin layer 101 to the thickness of the first resin layer 102 is more preferably within a range of 1:30 to 1:3 (second resin layer 101:first resin layer 102).

[0047] The ratio of the thickness of the second resin layer 101 to the thickness of the first resin layer 102 may be within a range of 1:15 to 1:5. The ratio of the thickness of the second resin layer 101 to the thickness of the first resin layer 102 can be defined by the ratio of the thickness of the first resin layer 102 to the thickness of the second resin layer 101 (first resin layer 102 / second resin layer 101). The thickness of the first resin layer 102 is preferably more than 1 time the thickness of the second resin layer 101, more preferably 3 times or more, and may be 5 times or more, and is preferably 100 times or less, more preferably 30 times or less, and may be 15 times or less.

[0048] A more preferred embodiment of the container according to this embodiment will be further described with reference to FIG. Figure 2 is a schematic diagram showing one embodiment of a container according to the present disclosure, in which Figures 2(a) and 2(c) are perspective views showing one embodiment of a container according to the present disclosure, and Figures 2(b-1) and 2(b-2) are schematic diagrams showing examples of cross-sectional shapes of the container according to the present disclosure.

[0049] The container according to the present disclosure can be used to protect the contents from external environments such as light and humidity, and to supply them as needed. As shown in FIG. 2(a), a container 100 according to one embodiment has an opening 103, a shoulder 104, a body 105, and a bottom 106 arranged in this order along the bottle axis AA.

[0050] In container 100, the opening area of ​​opening 103 is smaller than the average cross-sectional area of ​​body 105. In particular, the opening area of ​​opening 103 is preferably 25% or less of the average cross-sectional area of ​​the body. Here, the opening area of ​​opening 103 and the average cross-sectional area of ​​body 105 refer to values ​​in a direction perpendicular to the arrangement direction of opening 103 and body 105 (the bottle axial direction).

[0051] The shape of the opening forming the opening 103 is not particularly limited, and may be, for example, cylindrical or a polygonal tubular shape such as a square. In addition, a turnout may be provided at the end of the opening to prevent dripping, and a rib or a sloped portion that connects to the shoulder 104 may be provided to improve strength.

[0052] In the case of a large-capacity tank with a content volume exceeding 100 mL, particularly when multiple containers need to be stored side by side, such as ink tanks for inkjet printers, it is preferable that the cross-sectional shape of the body 105 be approximately elliptical or rectangular rather than circular. This allows for a higher ratio of the content volume to the storage space. Specifically, as shown in FIG. 2(b-1), a flat container is exemplified, in which the ratio of the longest diameter to the shortest diameter of the body 105 at cross section B perpendicular to the bottle axial direction is 3 or more. More preferably, the body 105 at cross section B is a rectangular container with a four-sided cross section, as shown in FIG. 2(b-2). The container 100 may be, for example, a rectangular container in which the outer surface of the body 105 is made up of four or more flat surfaces.

[0053] Although prismatic containers generally have lower strength against external loads and impacts than cylindrical containers, the strength can be improved by forming ribs on the surfaces forming the side portions. Preferably, a convex or concave flat rib 107 occupying more than half the area of ​​one of the surfaces is provided, as shown in FIG. 2(c). That is, in a prismatic container whose outer surface of the body 105 is composed of four or more flat surfaces, it is preferable that the flat rib 107 is provided on at least one of the four or more flat surfaces. Alternatively, facing ribs may be butted against each other and welded to form a beam structure supporting the container contents. When a rib is provided that does not form a beam structure, it is preferable that the flat rib 107 occupies more than half the area of ​​the flat surface on which the flat rib 107 is provided.

[0054] 2(c), it is more preferable to provide flat ribs 107 on the two opposing faces having larger areas of the rectangular body portion 105. Such flat ribs 107 can reduce the occurrence of liquid pooling when tilted compared to wavy or other non-flat ribs, and are particularly suitable for use in ink storage containers.

[0055] The corners of the ribs formed on the prismatic container and its sides, as well as the pinch-off areas where resin layers meet during molding, are prone to stress concentration due to external loads and impacts, making delamination likely to occur when the prismatic container contains a multilayer resin molded body. According to the inventors' research, sufficient interlayer adhesion strength can be achieved even in a multilayer resin molded body with many corners, particularly when the difference between the metal soap concentration in the second resin layer 101 and the metal soap concentration in the first resin layer 102 is 0.01% pt by mass or more and 2% pt by mass or less. This makes it possible to provide a prismatic container with practical usability and reduced delamination.

[0056] The container according to the present disclosure is preferably manufactured by hollow blow molding or multi-color molding. Furthermore, the container according to the present disclosure may be a container capable of holding (or storing) a liquid. The liquid to be held (or stored) may be, for example, ink, and the ink may be, for example, ink for inkjet printers.

[0057] In hollow blow molding, which uses blown air, or multi-color molding, a type of injection molding, the wall that makes up the container has a low stretch ratio, so it is strong enough to withstand loads applied to the wall. Therefore, even if the ink contained in the ink tank's inner wall sways in any direction, for example, when a certain amount of ink has been consumed, the ink can be securely held in the inner wall. This improves the overall durability of the ink tank.

[0058] More specific molding methods include injection blow molding, which involves blow molding an injection-molded multicolor preform, and multilayer direct blow molding. Any molding method can be selected depending on the shape and size of the container and the required shape precision.

[0059] The type and content of metal soap contained in the components constituting the multilayer resin molded body can be confirmed by mechanically cutting and separating the multilayers and then combining known separation and analytical techniques. There are no particular restrictions on the method or procedure. A simple method for verification is to combine elemental analysis such as energy dispersive X-ray analysis (EDX, EDS), pyrolysis gas mass chromatography mass spectrometry (pyrolysis GC-MS), and nuclear magnetic resonance spectroscopy (NMR).

[0060] In the above embodiment, an example is shown in which the first resin layer 102 and the second resin layer 101 are adjacent to each other, but the present disclosure is not limited to this, and another resin layer may be provided between the first resin layer 102 and the second resin layer 101.

[0061] Next, an embodiment of a container according to the present disclosure will be described, which is different from the embodiment described above. 6A and 6B are schematic diagrams showing one embodiment of a container according to the present disclosure, in which FIG. 6A is a cross-sectional view of the container, and FIG. 6B is a partially enlarged view of the container.

[0062] As shown in FIG. 6(a), a container 600 according to this embodiment has a multilayer resin molded body made up of a second resin layer 101 and a first resin layer 102 disposed adjacent to the second resin layer 101. In the container 600, the second resin layer 101 is disposed as the innermost layer of the container 600, forming an inner surface 603 of the container that comes into contact with the contents of the container 600. The first resin layer 102 is disposed as the outermost layer of the container 600, forming the circumferential surface of a body 105 of the container 600. The container 600 further includes a nozzle 601 that forms at least a part of an opening 103 of the container 600. In the container 600, the nozzle 601 is spin-welded to the second resin layer 101 at a spin-welded portion 602 shown in FIG. 6(b).

[0063] Furthermore, the container 600 may further include a lid (not shown) configured to be able to close the opening 103. The lid may be configured to be able to be opened and closed using, for example, a spiral concave-convex structure provided near the opening 103.

[0064] The container according to the present disclosure can be used as a container for medicines, agrochemicals, or food, or as a liquid storage container for fuel, detergent, ink, etc. In particular, the container according to the present disclosure can be suitably used as an ink tank to be installed in an inkjet printer.

[0065] The liquid holder according to the present disclosure is characterized by comprising the container described above that is capable of holding (or storing) a liquid, and the liquid held (or stored) in the container described above.

[0066] The ink tank according to the present disclosure is characterized in that the container described above, which is capable of holding (or storing) a liquid, is filled with ink as the liquid. The ink tank according to the present disclosure can be configured so as to be mountable in, for example, an inkjet printer having an inkjet head. In this case, the ink tank according to the present disclosure may further have an opening for supplying ink to the inkjet, in addition to the opening for filling the ink.

[0067] Furthermore, an inkjet printer according to the present disclosure is characterized by including the container according to the present disclosure. 7 illustrates an inkjet printer 300 including a container 310, ink 320 held in the container 310, an inkjet head 330, and a housing 340 that houses these components. The ink 320 in the container 310 is supplied to the inkjet head 330 and ejected from the inkjet head 330 onto a recording medium such as paper.

[0068] The containers provided in an inkjet printer may be ink cartridges that the user installs in the main body, or ink tanks that are pre-installed in the inkjet printer main body. Furthermore, the containers provided in an inkjet printer may be containers that already contain ink (such as ink cartridges), or may be empty containers (such as ink tanks).

[0069] When the container provided in the inkjet printer is an empty container (first container; for example, an ink tank), the user can fill, inject, or replenish the first container with ink held in another container (second container; for example, an ink bottle). To do this, the user simply takes ink that has been dispensed from the opening of the second container to the outside of the second container and pours it into the first container through the opening of the first container. In this way, the user can hold ink in the first container of the inkjet printer.

[0070] The container 100, 500, or 600 according to an embodiment of the present disclosure can be used for at least one of an ink cartridge, an ink tank, and an ink bottle as a container provided in an inkjet printer.

[0071] For example, when the container 600 is used as an ink bottle, an inkjet printer equipped with the ink bottle can be configured so that the nozzle 601 can be fitted into the main body of the inkjet printer. Empty ink cartridges and ink bottles can be recycled. [Example]

[0072] First, in order to evaluate the relationship between the metal soap concentration and the adhesive strength between the multiple layers, the following materials with different metal soap concentrations were prepared.

[0073] Calcium stearate (Kishida Chemical Co., Ltd.) was added as a metal soap to the base material to a predetermined concentration, and the mixture was kneaded at 190°C using a twin-screw extruder to produce the following resin pellets. Note that the blend ratios listed for the base material are mass-based ratios. The melt mass-flow rates (MFR) listed for the materials were measured according to JIS-K7210 at 230°C and 2.16 kgf. (Resin pellet A) Prime Polymer Co., Ltd.'s block copolymer PP "Prime Polypro (registered trademark) E701G (model number)" (virgin material, MFR = 0.5) as the base material, with the calcium stearate concentration adjusted to 0.005% by mass. (Resin pellet B-1) Made from recycled polypropylene "MAYPRENE PP (product name) MW666 (model number)" (MFR = 0.9) manufactured by Metro Wealth Polymer Sdn. Bhd., with calcium stearate concentration adjusted to 0.015% by mass. (Resin pellet B-2) Resin pellet B-1 with calcium stearate concentration adjusted to 0.105% by mass (Resin pellet B-3) Resin pellet B-1 with calcium stearate concentration adjusted to 1.005% by mass (Resin pellet B-4) Resin pellet B-1 with calcium stearate concentration adjusted to 1.505% by mass (Resin pellet B-5) Resin pellet B-1 with calcium stearate concentration adjusted to 2.005% by mass (Resin pellet B-6) Resin pellet B-1 with calcium stearate concentration adjusted to 2.505% by mass (Resin pellet B-7) A 2:1 blend of recycled polypropylene "M50GRAY (model number)" (MFR=28) manufactured by Panasonic Industrial Marketing & Sales Co., Ltd. and "KEIYO Polyethylene (product name) B5500 (model number)" manufactured by Keiyo Polyethylene Co., Ltd., with a calcium stearate concentration adjusted to 0.015% by mass. (Resin pellet B-8) Resin pellet B-7 with calcium stearate concentration adjusted to 1.505% by mass (Resin pellet B-9) Resin pellet B-7 with calcium stearate concentration adjusted to 2.005% by mass (Resin pellet B-10) Resin pellet B-7 with calcium stearate concentration adjusted to 2.505% by mass (Resin pellet B-11) A 67:30:3 blend of recycled polypropylene "M50GRAY (model number)" (MFR=28) manufactured by Panasonic Industrial Marketing & Sales Co., Ltd., "KEIYO Polyethylene (product name) B5500 (model number)" manufactured by Keiyo Polyethylene Co., Ltd., and acrylic-modified PTFE "Metablen (trademark) A-3000 (model number)" manufactured by Mitsubishi Chemical Corporation (equivalent to a PTFE concentration of 20% by weight), with calcium stearate concentration adjusted to 0.015% by mass. (Resin pellet B-12) Resin pellet B-12 "M50GRAY (model number)", "KEIYO Polyethylene (product name) B5500 (model number)", and "Metabrene (trademark) A-3000 (model number)" are blended in a ratio of 66:30:4, with the calcium stearate concentration adjusted to 0.015% by mass. (Resin pellet B-13) Resin pellet B-12 "M50GRAY (model number)", "KEIYO Polyethylene (product name) B5500 (model number)", and "Metabrene (trademark) A-3000 (model number)" are blended in a ratio of 65:30:5, with the calcium stearate concentration adjusted to 0.015% by mass. (Resin pellet B-14) Resin pellet B-11, except that the calcium stearate concentration was adjusted to 2.005% by mass. (Resin pellet B-15) Resin pellet B-12 with calcium stearate concentration adjusted to 2.005% by mass. (Resin pellet B-16) Resin pellet B-13, except that the calcium stearate concentration was adjusted to 2.005% by mass.

[0074] Each resin pellet was injection molded using an injection molding machine "SE-180D (product name)" manufactured by Sumitomo Heavy Industries, Ltd. under the following conditions: cylinder temperature 230°C, mold temperature 40°C, average injection speed 200 mm / sec, and holding pressure time 40 sec. This produced rectangular test pieces type B1 (length 80 mm x width 10 mm x thickness 4 mm) specified in JIS K7152-1.

[0075] The thermal expansion coefficient (linear expansion coefficient) in the thickness direction at the center of each rectangular specimen was measured in the range of 20°C to 80°C using a TMA Q400 (product name) thermomechanical analyzer (manufactured by TA Instruments). The temperature was raised from 20°C to 80°C at a rate of 5°C / min and held for 10 minutes, after which two cycles of lowering and raising the temperature in the range of 80°C to 20°C were repeated, and the average value of the slope of each thermal expansion coefficient (ppm) versus temperature was taken as the linear expansion coefficient.

[0076] Furthermore, the strip-shaped test piece of resin pellet A and the strip-shaped test piece of resin pellets B-1 to B-16 were brought into contact so that only the 20 mm long x 10 mm wide portion of the 80 mm long x 10 mm wide surface overlapped, and the periphery was held in place by a stainless steel block. After that, they were heated at 200°C under natural load for 5 minutes in a small heat press machine (product name) manufactured by AS ONE Corporation to prepare welded test pieces.

[0077] The end faces of the welded test pieces opposite to the welded surfaces of the rectangular test piece of resin pellet A and the rectangular test pieces of resin pellets B-1 to B-16 were fixed to a tensile test jig as tensile end faces. A tensile test was then performed at a speed of 10 mm / min using an Instron universal testing machine 5581 (model number). The maximum tensile load measured was taken as the adhesion strength. [Table 1]

[0078] Table 1 summarizes the difference in metal soap concentration and adhesion between resin pellet A and resin pellets B-1 to 10 in each multilayer resin molded body. Also, Figure 3 is a graph showing the relationship between the difference in metal soap concentration and adhesion for the multilayer resin molded bodies of Examples 1-1 to 10.

[0079] As is clear from FIG. 3, when the difference in metal soap concentration between adjacent layers of the multi-layered resin molded article exceeded 2% by mass, the adhesive strength between the layers decreased significantly. [Table 2]

[0080] Table 2 summarizes the differences in metal soap concentration, differences in linear expansion coefficient, and adhesion between resin pellet A and resin pellets B-7 and B-8, and PTFE-containing resin pellets B-11 to 16. It can be seen that the PTFE-containing resin pellets B-11 to 16 have a smaller difference in linear expansion coefficient and improved adhesion compared to Examples 1-7 and 1-8.

[0081] Next, an example of manufacturing a container using direct blow molding will be described in detail with reference to Fig. 4. Note that the manufacturing method of a container according to the present disclosure is not limited to the direct blow molding method (extrusion blow molding method) described below. For example, injection blow molding, extrusion stretch blow molding, etc. may also be used, and the method is not limited to the hot parison method, cold parison method, etc.

[0082] 4(a) to 4(c) are diagrams showing steps in an example of manufacturing a container according to the present disclosure using multilayer direct blow molding.

[0083] The multilayer direct blow molding machine shown in Figure 4(a) is provided with a first extruder 201 that extrudes a resin that forms the second resin layer 101, and a second extruder 202 that extrudes a resin that forms the first resin layer 102. When producing a multilayer resin molded product consisting of three or more resin layers, an extruder is further provided to form an outer layer, but the third and subsequent extruders are not shown in Figure 4 for ease of explanation.

[0084] Although the capacity of the extruder is not particularly specified, in a container having a multilayer resin molded body, the other layers are often made thicker than the second resin layer, which serves as a barrier layer, to obtain strength. Therefore, the extrusion rate per hour of the first extruder 201 is often less than the extrusion rate per hour of the other extruders.

[0085] The temperature setting for the resin in the extruder may be set according to the type of resin being extruded. When a virgin material is used for the second resin layer 101 and a recycled material of the same type of resin as the virgin material is used for the first resin layer 102, the set temperature for the recycled material may be lowered depending on the degree of deterioration due to the thermal history of the resin. In this example, the temperature suitable for extruding polypropylene resin was set to 230°C for the resin forming the second resin layer and 220°C for the resin forming the first resin layer, and molding was performed as follows.

[0086] First, the resin extruded from each extruder was formed into a cylindrical ring shape. The resin forming the first resin layer 102 supplied from the second extruder 202 was laminated on the outer cylindrical surface of the resin forming the second resin layer 101 supplied from the first extruder 201. Then, a parison 204 was prepared by integrating the parisons extruded from the lower end of the head die 203. Here, resin pellets A (Example 2) or resin pellets B-1 (Comparative Example 1) were used as the resin forming the second resin layer 101, and resin pellets B-1 (Example 2 and Comparative Example 1) were used as the resin forming the first resin layer 102.

[0087] Next, a mold 205 arranged to sandwich the parison 204 was moved from the state shown in Fig. 4(b) to the state shown in Fig. 4(c) to pinch the parison 204. The part where the parison is almost completely sandwiched between the molds and the parison is pinched off is the pinch-off part 206.

[0088] Subsequently, as shown in FIG. 4(c), blow air was injected from an air nozzle 207 to blow-mold the outer shape into a shape that matched the cavity shape of a mold 205.

[0089] Fig. 5 shows a schematic diagram of a rectangular container manufactured by the manufacturing example described with reference to Fig. 4. Fig. 5(a) is a perspective view showing the appearance of the container, and Fig. 5(b) is a schematic diagram showing the cross-sectional shape of the container at cross section B in Fig. 5(a).

[0090] As shown in Figure 5(a), the rectangular container 500 is a rectangular flat container with interior dimensions of 115 mm long axis width x 40 mm short axis width x 90 mm height, and has an opening with an inner diameter of 20 mm at the top. Furthermore, as shown in Figure 5(b), the container 500 has a concave flat rib measuring 80 mm wide x 70 mm high x 6 mm deep in the center of the two largest surfaces of the four surfaces that form the body. The rib depth is carved at an angle of 80°.

[0091] In Example 2, the container 500 was manufactured using resin pellets A as the material for forming the second resin layer 101. In Comparative Example 1, the container 500 was manufactured using resin pellets B-1 as the material for forming the second resin layer 101.

[0092] The containers 500 according to Examples 2 and 3 and the container 500 according to Comparative Example 1 were evaluated for the presence or absence of aggregate formation and peeling when inkjet ink containing a black pigment (carbon black) was sealed inside and held for one day.

[0093] Table 2 shows the results of the above evaluations and the average wall thicknesses of corners 301, 302, and 303, where stress is most concentrated during blow molding and in response to external loads and impacts. The average wall thicknesses of corners 301, 302, and 303 were measured by cutting the container along a plane perpendicular to the flat rib and passing through the midpoint of the rib height. For each of the four corners, 301 and 302, the average wall thickness was calculated as the average of the values ​​measured on an extension of the line forming the 80° rib recess on the outside (102 side) of the container. For 303, the average wall thickness was calculated as the average of the values ​​measured on a line intersecting at a 45° angle with the two frame lines on the outside (102 side) of the container that form the vertices of the four corners. As shown in Table 3, in Examples 2 and 3, no agglomerates were formed even when recycled resins containing metal soap were used as the structural material, and containers were obtained that had minimal impact on the properties of the contents. [Table 3]

[0094] The present disclosure is not limited to the above-described embodiments and examples, and many modifications are possible within the technical concept of the present disclosure. Furthermore, the effects described in the embodiments and examples of the present disclosure are merely a list of the most preferable effects resulting from the present disclosure, and the effects of the present disclosure are not limited to those described in the embodiments and examples. The technology described in this specification can contribute to the realization of a sustainable society, such as a decarbonized / recycling-based society.

[0095] The disclosure according to the embodiment of the present disclosure includes the following configuration. (Configuration 1) A container having a multilayer resin molded body, the multilayer resin molded body includes a first resin layer and a second resin layer located more inward of the container than the first resin layer, the resin composition constituting the second resin layer contains a polyolefin resin, In at least a part of an area where the first resin layer and the second resin layer overlap, the thickness of the second resin layer is smaller than the thickness of the first resin layer; A container characterized in that the concentration of the metal soap in the second resin layer is lower than the concentration of the metal soap in the first resin layer. (Configuration 2) 2. The container according to claim 1, wherein the concentration of the metal soap in the first resin layer is 0.01% by mass or more. (Configuration 3) 3. The container according to claim 1, wherein the difference between the concentration of the metal soap in the first resin layer and the concentration of the metal soap in the second resin layer is 0.01 mass % pt or more. (Configuration 4) 4. The container according to any one of configurations 1 to 3, wherein the concentration of the metal soap in the first resin layer is 2.0% by mass or less. (Configuration 5) 5. The container according to any one of configurations 1 to 4, wherein the concentration of the metal soap in the second resin layer is less than 0.01% by mass. (Configuration 6) 6. The container according to any one of configurations 1 to 5, wherein the difference between the concentration of the metal soap in the first resin layer and the concentration of the metal soap in the second resin layer is 2.0 mass % pt or less. (Configuration 7) 7. The container according to any one of configurations 1 to 6, wherein the first resin layer and the second resin layer are adjacent to each other. (Configuration 8) 8. The container according to any one of configurations 1 to 7, wherein the second resin layer is disposed so as to be in contact with the contents of the container. (Configuration 9) The container according to any one of configurations 1 to 8, wherein the second resin layer is disposed so as to be in contact with the contents of the container, and the first resin layer is disposed so as to be adjacent to the second resin layer. (Configuration 10) 10. The container according to any one of configurations 1 to 9, wherein the first resin layer is exposed to the outside of the container. (Configuration 11) 11. The container according to any one of configurations 1 to 10, wherein the metal soap contained in the first resin layer and the metal soap contained in the second resin layer contain a compound represented by the following formula (1): (C n H 2n+1 COO)2·M (1) (In formula (1), n ​​is an integer of 7 or more and 20 or less, and M represents an alkaline earth metal atom or a zinc atom.) (Configuration 12) 12. The container according to any one of configurations 1 to 11, wherein the metal soap contained in the second resin layer is a fatty acid salt of calcium. (Configuration 13) 13. The container according to any one of configurations 1 to 12, wherein the metal soap contained in the second resin layer is a salt of stearic acid. (Configuration 14) 14. The container according to any one of configurations 1 to 13, wherein the resin composition constituting the first resin layer contains a polyolefin resin. (Configuration 15) 15. The container according to any one of configurations 1 to 14, wherein the resin composition constituting the second resin layer comprises a polymer of an ethylene monomer or a polymer of a propylene monomer. (Configuration 16) 16. The container according to claim 15, wherein the content of the polymer of ethylene monomer or the polymer of propylene monomer in the resin composition constituting the second resin layer is 50% by mass or more. (Configuration 17) 17. The container according to any one of configurations 1 to 16, wherein the resin composition constituting the second resin layer contains polytetrafluoroethylene and a derivative of polytetrafluoroethylene. (Configuration 18) 18. The container according to any one of configurations 1 to 17, wherein the resin composition constituting the second resin layer contains a fibrous filler. (Configuration 19) The container according to any one of Structures 1 to 18, wherein the difference in linear expansion coefficient between the resin composition constituting the first resin layer and the resin composition constituting the second resin layer in the range of 20°C to 80°C is 10 ppm / °C or less. (Structure 20) 20. The container according to any one of configurations 1 to 19, wherein the thickness of the first resin layer is 3 times or more and 30 times or less the thickness of the second resin layer in at least the portion. (Configuration 21) 21. The container according to any one of configurations 1 to 20, wherein the thickness of the second resin layer in at least the portion is 0.01 mm or more and 3 mm or less. (Configuration 22) 22. The container according to any one of configurations 1 to 21, wherein the thickness of the first resin layer in at least the portion is 0.05 mm or more and 5 mm or less. (Configuration 23) The container has an opening for the contents to enter and exit, and a body for containing the contents, the first resin layer and the second resin layer are provided on at least the trunk portion, 23. The container according to any one of configurations 1 to 22, wherein the opening area of ​​the opening is smaller than the average cross-sectional area of ​​the body in a direction perpendicular to the direction in which the opening and the body are arranged. (Configuration 24) 24. The container according to claim 23, wherein the thickness of the second resin layer in the body portion is smaller than the thickness of the first resin layer. (Configuration 25) 25. The container according to claim 23 or 24, wherein the opening area of ​​the opening is 25% or less of the average cross-sectional area of ​​the body. (Configuration 26) 26. The container according to any one of aspects 23 to 25, wherein the ratio of the longest diameter to the shortest diameter of the cross section of the body is 3 or more in a direction perpendicular to the arrangement direction of the opening and the body. (Configuration 27) 27. The container according to any one of configurations 23 to 26, wherein the outer surface of the body portion is made up of four or more flat surfaces. (Configuration 28) At least one of the four or more flat surfaces is provided with a flat rib; 28. The container of claim 27, wherein the planar rib occupies more than half of the area of ​​the plane on which the planar rib is disposed. (Configuration 29) 29. The container according to any one of configurations 1 to 28, produced by hollow blow molding or multi-color molding. (Configuration 30) 30. A container according to any one of aspects 1 to 29, capable of holding a liquid. (Configuration 31) A liquid holder comprising the container according to aspect 30 and a liquid held in the container. (Configuration 32) 31. The container according to any one of aspects 23 to 30, further comprising a lid configured to be able to close the opening. (Configuration 33) The container according to any one of configurations 23 to 30 and 32, further comprising a nozzle that constitutes at least a part of the opening. (Configuration 34) The container according to any one of configurations 23 to 30, 32, and 33, further comprising a lid configured to be able to close the opening and a nozzle that forms at least a part of the opening. (Configuration 35) 31. The container of embodiment 30, wherein the liquid is ink. (Configuration 36) 36. The container of embodiment 35, wherein the ink is ink for an inkjet printer. (Configuration 37) An ink tank comprising the container according to configuration 35 or 36 filled with the ink. (Configuration 38) An inkjet printer comprising a container according to any one of configurations 30, 35, and 36. [Industrial Applicability]

[0096] The technology described in this specification can contribute to the realization of a sustainable society, such as a decarbonized / recycling-based society. [Explanation of symbols]

[0097] 100, 310, 500, 600 containers 101 Second resin layer 102 1st resin layer 103 Opening 105 Torso 107 Flat Rib 201 First Extruder 202 No. 2 Extruder 203 Head Die 205 Molds 300 inkjet printers 601 Nozzle

Claims

1. A container having a multilayer resin molded body, The multilayer resin molded body includes a first resin layer and a second resin layer located more inward of the container than the first resin layer, the resin composition constituting the second resin layer contains a polyolefin resin, A container characterized in that in at least a portion of the area where the first resin layer and the second resin layer overlap, the thickness of the second resin layer is smaller than the thickness of the first resin layer, and the concentration of metal soap in the second resin layer is lower than the concentration of metal soap in the first resin layer.

2. The container according to claim 1 , wherein the concentration of the metal soap in the first resin layer is 0.01% by mass or more.

3. 2. The container according to claim 1, wherein the difference between the concentration of the metal soap in the first resin layer and the concentration of the metal soap in the second resin layer is 0.01 mass % pt or more.

4. The container according to claim 1 , wherein the concentration of the metal soap in the first resin layer is 2.0% by mass or less.

5. The container according to claim 1 , wherein the concentration of the metal soap in the second resin layer is less than 0.01% by mass.

6. 2. The container according to claim 1, wherein the difference between the concentration of the metal soap in the first resin layer and the concentration of the metal soap in the second resin layer is 2.0 mass% pt or less.

7. The container according to any one of claims 1 to 6, wherein the first resin layer and the second resin layer are adjacent to each other.

8. The container according to any one of claims 1 to 6, wherein the second resin layer is disposed so as to be in contact with the contents of the container.

9. The container according to any one of claims 1 to 6, wherein the second resin layer is arranged so as to be in contact with the contents of the container, and the first resin layer is arranged so as to be adjacent to the second resin layer.

10. The container according to any one of claims 1 to 6, wherein the first resin layer is exposed to the outside of the container.

11. The container according to any one of claims 1 to 6, wherein the metal soap contained in the first resin layer and the metal soap contained in the second resin layer contain a compound represented by the following formula (1): (C ｎ H ２ｎ＋１ COO) ２ ・M (1) (In formula (1), n ​​is an integer of 7 or more and 20 or less, and M represents an alkaline earth metal atom or a zinc atom.)

12. 7. The container according to claim 1, wherein the metal soap contained in the second resin layer is a fatty acid salt of calcium.

13. 7. The container according to claim 1, wherein the metal soap contained in the second resin layer is a salt of stearic acid.

14. The container according to any one of claims 1 to 6, wherein the resin composition constituting the first resin layer contains a polyolefin resin.

15. 7. The container according to claim 1, wherein the resin composition constituting the second resin layer contains a polymer of an ethylene monomer or a polymer of a propylene monomer.

16. The container according to claim 15, wherein the content of the ethylene monomer polymer or the propylene monomer polymer in the resin composition constituting the second resin layer is 50% by mass or more.

17. 7. The container according to claim 1, wherein the resin composition constituting the second resin layer contains polytetrafluoroethylene and a derivative of polytetrafluoroethylene.

18. 7. The container according to claim 1, wherein the resin composition constituting the second resin layer contains a fibrous filler.

19. The difference in linear expansion coefficient between the resin composition constituting the first resin layer and the resin composition constituting the second resin layer in the range of 20 ° C to 80 ° C is 10 ppm / ° C or less. A container according to any one of claims 1 to 6.

20. The container according to any one of claims 1 to 6, wherein in at least the portion, the thickness of the first resin layer is 3 times or more and 30 times or less the thickness of the second resin layer.

21. The container according to any one of claims 1 to 6, wherein the thickness of the second resin layer is 0.01 mm or more and 3 mm or less in at least the portion.

22. The container according to any one of claims 1 to 6, wherein the thickness of the first resin layer is 0.05 mm or more and 5 mm or less in at least the portion.

23. The container has an opening for the contents to enter and exit, and a body for containing the contents, the first resin layer and the second resin layer are provided on at least the trunk portion, 7. The container according to claim 1, wherein the opening area of ​​the opening is smaller than the average cross-sectional area of ​​the body in a direction perpendicular to the direction in which the opening and the body are arranged.

24. 24. The container according to claim 23, wherein the thickness of the second resin layer in the body portion is smaller than the thickness of the first resin layer.

25. 24. The container according to claim 23, wherein the open area of ​​the opening is 25% or less of the average cross-sectional area of ​​the body.

26. 24. The container according to claim 23, wherein the ratio of the longest diameter to the shortest diameter of the cross section of the body in a direction perpendicular to the arrangement direction of the opening and the body is 3 or more.

27. 24. The container of claim 23, wherein the exterior surface of the body comprises four or more flat surfaces.

28. a flat rib is provided on at least one of the four or more flat surfaces; 28. The container of claim 27, wherein the planar rib occupies more than half of the area of ​​the plane on which the planar rib is disposed.

29. The container according to any one of claims 1 to 6, which is produced by hollow blow molding or multi-color molding.

30. The container according to any one of claims 1 to 6, capable of holding a liquid.

31. A liquid holder comprising the container according to claim 30 and the liquid held in the container.

32. 24. The container of claim 23, further comprising a lid configured to be able to close the opening.

33. 24. The container of claim 23, further comprising a nozzle defining at least a portion of the opening.

34. 24. The container of claim 23, further comprising a lid configured to be able to close the opening and a nozzle configured to direct the contents through at least a portion of the opening.

35. 31. The container of claim 30, wherein the liquid is ink.

36. 36. The container of claim 35, wherein the ink is an ink jet printer ink.

37. An ink tank comprising the container according to claim 35 filled with the ink.

38. An ink jet printer comprising the container according to claim 30.

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