Oxygen-absorbing sealant film

Abstract

In one embodiment of the present invention, as shown in fig. 1, an oxygen-absorbing sealant film 10 according to the present invention has at least a first surface resin layer 12, an oxygen-absorbing layer 14, and a second surface resin layer 16 in this order. The oxygen-absorbing layer 14 contains at least an iron powder and a polypropylene resin. Additionally, at least one of (i) and (ii) is satisfied:　The first surface resin layer 12 or the second surface resin layer 16 contains a polypropylene elastomer having a density of 0.900 g / cm3 or less, and the content ratio thereof is 5 mass% or more.

Description

Oxygen-absorbing sealant film

[0001] The present invention relates to oxygen-absorbing sealant films, and more particularly to oxygen-absorbing sealant films for flexible packaging.

[0002] Numerous technologies have been proposed for imparting oxygen absorption functionality to packaging materials themselves by using oxygen-absorbing resin compositions in which oxygen absorbers are dispersed in polyolefin resin. Various inorganic and organic oxygen absorbers are known, and those consisting of iron powder and an oxidation accelerator are preferably used from the viewpoint of oxygen absorption performance, thermal stability to withstand high temperatures during processing, economy, and hygiene. These iron-based oxygen absorbers are generally in granular or powder form.

[0003] Furthermore, known methods such as co-extrusion lamination, extrusion lamination, and dry lamination are used as methods for manufacturing oxygen-absorbing laminated films containing iron-based oxygen absorbers. Co-extrusion lamination is a method of laminating by simultaneously heating and melting the oxygen-absorbing resin composition that constitutes the oxygen-absorbing layer and the resin layers that constitute the other layers. Extrusion lamination is a method of laminating by heating and melting only the oxygen-absorbing resin composition and laminating it with the resin films that constitute the other layers. Dry lamination is a method of forming a single layer of oxygen-absorbing film in advance and then bonding it to the films that form the other layers using an adhesive.

[0004] As a packaging container obtained by such a method, Patent Document 1 discloses an oxygen-absorbing plastic container having an intermediate layer consisting of at least two layers: an oxygen-absorbing thermoplastic resin layer and an oxygen barrier resin layer, with an inner layer and an outer layer made of thermoplastic resin laminated on both sides. In this oxygen-absorbing plastic container, the oxygen-absorbing thermoplastic resin layer is a blend of polypropylene resin and polyethylene resin. The thermoplastic resins of the inner and outer layers are polypropylene resin, or a blend of polypropylene resin and polyethylene resin. Patent Document 1 discloses that the oxygen-absorbing function is greatly improved by using random polypropylene in the oxygen-absorbing thermoplastic resin layer.

[0005] Furthermore, Patent Document 2 discloses a method for producing an oxygen-absorbing laminated film consisting of at least an oxygen barrier layer A, an intermediate layer B, an adhesive strengthening layer C, an iron-based oxygen scavenger-containing oxygen absorbing layer D, and a sealant layer E from the outside in. This method is characterized by co-extruding and laminating the adhesive strengthening layer C and the iron-based oxygen scavenger-containing oxygen absorbing layer D, or the adhesive strengthening layer C, the iron-based oxygen scavenger-containing oxygen absorbing layer D, and the sealant layer E onto the surface of the intermediate layer B.

[0006] Japanese Patent Publication No. 2001-58363 Japanese Patent Publication No. 2001-260285

[0007] As described in Patent Document 1, when random polypropylene is used in the oxygen-absorbing layer, there were no problems with the physical strength of the packaging container when it was used in a bottle as described in Patent Document 1. However, when this was simply used in the oxygen-absorbing laminated film described in Patent Document 2, particularly in a packaging bag, it could not withstand external pressure and the bag would sometimes rupture.

[0008] Therefore, the present invention provides a novel oxygen-absorbing sealant film having significantly improved physical strength.

[0009] The inventors, after diligent study, found that the above problems could be solved by the following means, and thus completed the present invention. That is, the present invention is as follows: <Aspect 1> An oxygen-absorbing sealant film having at least a first surface resin layer, an oxygen-absorbing layer, and a second surface resin layer in this order, and having these layers fused to each other, wherein the first surface resin layer and the second surface resin layer contain a polypropylene resin, and the oxygen-absorbing layer contains at least iron powder and a polypropylene resin, and satisfies at least one of the following (i) and (ii): (i) The first surface resin layer has a density of 0.900 g / cm³ ３ (ii) The second surface resin layer contains the following polypropylene elastomer, and the content of the polypropylene elastomer in the first surface resin layer is 5% by mass or more relative to the mass of the first surface resin layer, and / or (ii) the density of the second surface resin layer is 0.900 g / cm³ ３An oxygen-absorbing sealant film containing the following polypropylene elastomer, wherein the content of the polypropylene elastomer in the second surface resin layer is 5% by mass or more relative to the mass of the second surface resin layer. <Aspect 2> The oxygen-absorbing sealant film according to Aspect 1, wherein the content of the polypropylene elastomer in the first surface resin layer is 55% by mass or less, and / or the content of the polypropylene elastomer in the second surface resin layer is 55% by mass or less. <Aspect 3> The oxygen-absorbing sealant film according to Aspect 1, wherein the first surface resin layer and the second surface resin layer further contain block polypropylene. <Aspect 4> The oxygen-absorbing sealant film according to any one of Aspects 1 to 3, wherein the oxygen-absorbing layer contains polypropylene elastomer. <Aspect 5> The oxygen-absorbing sealant film according to Aspect 4, wherein the content of the polypropylene elastomer in the oxygen-absorbing layer is 40% by mass or more relative to the total mass of the resin components constituting the oxygen-absorbing layer. <Aspect 6> An oxygen-absorbing sealant film according to any one of aspects 1 to 5, having a thickness of 100 μm or less. <Aspect 7> An oxygen-absorbing sealant film according to any one of aspects 1 to 6, which is an inflation film. <Aspect 8> A packaging laminate having an oxygen-absorbing sealant film according to any one of aspects 1 to 7 and a base layer, wherein the base layer is laminated on the first surface resin layer. <Aspect 9> A packaging bag having the packaging laminate according to aspect 8. <Aspect 10> A lid material having the packaging laminate according to aspect 8.

[0010] According to the present invention, a novel oxygen-absorbing sealant film with significantly improved physical strength can be provided.

[0011] Figure 1 is a side cross-sectional view of the oxygen-absorbing sealant film of the present invention. Figure 2 is a side cross-sectional view of the packaging laminate of the present invention.

[0012] Oxygen-absorbing sealant film The oxygen-absorbing sealant film of the present invention is an oxygen-absorbing sealant film having at least a first surface resin layer, an oxygen-absorbing layer, and a second surface resin layer in this order, and these layers are fused to each other, wherein the first surface resin layer and the second surface resin layer contain a polypropylene-based resin, the oxygen-absorbing layer contains at least iron powder and a polypropylene-based resin, and the first surface resin layer has a density of 0.900 g / cm ３ or less, and the content of the polypropylene elastomer in the first surface resin layer is 5% by mass or more based on the mass of the first surface resin layer, and / or the second surface resin layer has a density of 0.900 g / cm ３ or less, and the content of the polypropylene elastomer in the second surface resin layer is 5% by mass or more based on the mass of the second surface resin layer.

[0013] The present inventors have found that favorable physical strength can be obtained by including the above polypropylene elastomer in the first and / or second surface resin layer. While not wishing to be bound by theory, it is believed that this is because the elasticity provided by the polypropylene elastomer can absorb external forces such as external pressure.

[0014] Furthermore, as will be described later, the present inventors have found that favorable oxygen absorption properties can be obtained when the above polypropylene elastomer is included in the oxygen-absorbing layer in an amount of 40% by mass or more based on the total mass of resin components constituting the oxygen-absorbing layer. In the course of this study, the inventors have found that when a polypropylene elastomer having the above density is included in a small amount, the small amount of polypropylene elastomer localizes, causing steric hindrance, which results in reduced oxygen absorption properties.

[0015] In response to this, the inventors have found that when the above-mentioned polypropylene elastomer is included in at least one of the first and second surface resin layers at a concentration of 5% by mass or more, the oxygen absorption performance is unexpectedly not impaired. Although we do not wish to be bound by theory, this is thought to be because, unlike the oxygen absorption layer, the first and second surface resin layers do not contain iron powder, and therefore the polypropylene elastomer contained therein hardly intervenes between the outside and the iron powder, making them less susceptible to the effects of the steric obstruction described above.

[0016] In one aspect of the present invention, as shown in Figure 1, the oxygen-absorbing sealant film 10 of the present invention is an oxygen-absorbing sealant film 10 having at least a first surface resin layer 12, an oxygen-absorbing layer 14, and a second surface resin layer 16 in this order, and having these layers fused to each other, wherein the first surface resin layer 12 and the second surface resin layer 16 contain a polypropylene resin, and the oxygen-absorbing layer 14 contains at least iron powder and a polypropylene resin, and satisfies at least one of the following (i) and (ii): the first surface resin layer 12 has a density of 0.900 g / cm³ ３ The second surface resin layer 16 contains the following polypropylene elastomer, and the content of the polypropylene elastomer in the first surface resin layer 12 is 5% by mass or more relative to the mass of the first surface resin layer 12, and / or the density of the second surface resin layer 16 is 0.900 g / cm³ ３ The following polypropylene elastomer is contained, and the content of the polypropylene elastomer in the second surface resin layer is 5% by mass or more relative to the mass of the second surface resin layer 16.

[0017] The thickness of the oxygen-absorbing sealant film of the present invention may be 100 μm or less. This thickness may be 100 μm or less, 95 μm or less, 90 μm or less, 85 μm or less, 80 μm or less, or 75 μm or less, and may also be 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, 55 μm or more, 60 μm or more, or 65 μm or more.

[0018] The oxygen-absorbing sealant film of the present invention can be produced by simultaneously forming and laminating a first surface resin layer, an oxygen-absorbing layer, and a second surface resin layer by a multilayer T-die method or a multilayer inflation method. That is, the oxygen-absorbing sealant film of the present invention may be a T-die film or an inflation film. In addition, the surface resin layer formed and laminated by a coextrusion method such as the multilayer T-die method and the multilayer inflation method as described above may sometimes be referred to as a skin layer.

[0019] In particular, when the oxygen-absorbing sealant film is an inflation film, high heat seal strength can be obtained. Without wishing to be bound by theory, this is because when the resin composition constituting the first surface resin layer is extruded from the ring-shaped die of an inflation molding machine, it is immediately exposed to air and cooled, and during heat sealing, the oxygen-absorbing layer is back-supported by the first surface resin layer to relieve stress, which is believed to be because this can suppress the exposure of iron powder to the surface.

[0020] On the other hand, in the case of an inflation film, since the resin composition constituting the oxygen-absorbing layer is gradually cooled, crystallization of the resin proceeds, which has caused the problem that sufficient oxygen absorption performance cannot be obtained. However, the present inventors have found that when a specific polypropylene elastomer is contained in the oxygen-absorbing layer as in the present invention, the oxygen absorption performance is not impaired.

[0021] The oxygen-absorbing sealant film of the present invention may be an oxygen-absorbing sealant film for packaging bags or for lid materials.

[0022] Hereinafter, each component of the present invention will be described.

[0023] <First Surface Resin Layer> The first surface resin layer is a layer that is fused together with the oxygen-absorbing layer. The first surface resin layer contains a polypropylene-based resin. The first surface resin layer can serve as a layer to be bonded to a base material layer in the packaging laminate mentioned below.

[0024] As long as at least one of the first and second surface resin layers contains a polypropylene elastomer, the resin constituting the first surface resin layer may be different from or the same as the resin constituting the second surface resin layer. For example, if the second surface resin layer contains a polypropylene elastomer, the first surface resin layer may consist only of homopolypropylene, random polypropylene, or block polypropylene, or it may consist of a mixture of these polypropylenes and a polypropylene elastomer.

[0025] The first surface resin layer does not need to contain inorganic particles, such as iron powder as mentioned later in relation to the oxygen absorption layer.

[0026] The thickness of the first surface resin layer may be greater than 10 μm and less than or equal to 100 μm. This thickness may be greater than 10 μm, 12 μm or more, or 15 μm or more, and may also be 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, less than 50 μm, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, or 23 μm or less.

[0027] (Polypropylene Resins) In this specification, polypropylene resins are resins in which the main chain of the polymer contains 30 mol% or more, 40 mol% or more, 50 mol% or more, more than 50 mol%, 60 mol% or more, 70 mol% or more, or 80 mol% or more of repeating units of propylene groups, and examples include polypropylene (PP) homopolymers, random polypropylene (random PP), blocked polypropylene (block PP), chlorinated polypropylene, acid-modified polypropylene, polypropylene elastomers, derivatives thereof, and mixtures thereof.

[0028] Further, among the above "polypropylene-based resins", "polypropylene homopolymer" refers to a homotype homopolymer polymerized only from propylene, "random polypropylene" refers to a random-type copolymer obtained by polymerizing propylene in the coexistence of a comonomer such as ethylene, and "block polypropylene" refers to a block-type copolymer obtained by polymerizing propylene and then further polymerizing in the coexistence of a comonomer such as ethylene.

[0029] The density of the polypropylene-based resin may be 0.840 g / cm ３ or more, 0.845 g / cm ３ or more, 0.850 g / cm ３ or more, 0.855 g / cm ３ or more, 0.860 g / cm ３ or more, 0.870 g / cm ３ or more, 0.880 g / cm ３ or more, 0.885 g / cm ３ or more, 0.890 g / cm ３ or more, or 0.895 g / cm ３ or more, or 0.920 g / cm ３ or more, and may be 0.950 g / cm ３ or less, 0.940 g / cm ３ or less, 0.930 g / cm ３ or less, 0.925 g / cm ３ or less, 0.920 g / cm ３ or less, 0.915 g / cm ３ or less, 0.910 g / cm ３ or less, or 0.905 g / cm ３ or less.

[0030] (Polypropylene-based resin: Polypropylene elastomer) In general, a thermoplastic elastomer is composed of a plastic component (hard segment) and an elastic component (soft segment), and thus refers to a polymer that is plasticized at high temperature and exhibits properties of a rubber elastic body at normal temperature. In particular, polypropylene elastomer is a thermoplastic elastomer containing polypropylene as a hard segment.

[0031] In particular, the polypropylene elastomer in the present invention is contained in the first surface resin layer and / or the second surface resin layer.

[0032] The density of polypropylene elastomer is 0.900 g / cm³. ３ The density is as follows: 0.900 g / cm³ ３ Below, 0.895g / cm ３ Below, 0.890g / cm ３ Below, 0.885g / cm ３ Below, 0.880g / cm ３ Below, 0.875g / cm ３ The following, or 0.870 g / cm³ ３ It may be less than or equal to 0.840 g / cm³. ３ Above, 0.845g / cm ３ Above, 0.850g / cm ３ Above, 0.855g / cm ３ Above, or 0.860 g / cm³ ３ That's all.

[0033] The polypropylene elastomer content may be 5% by mass or more and 55% by mass or less relative to the mass of the first surface resin layer. This content may be 5% by mass or more, 10% by mass or more, 15% by mass or more, 17% by mass or more, or 55% by mass or less, 50% by mass or less, 47% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 33% by mass or less. Of these, a content of 47% by mass or less, and particularly 33% by mass or less, is preferred from the viewpoint of film formation properties.

[0034] (Polypropylene resins: Polypropylene resins other than polypropylene elastomers) Polypropylene resins other than polypropylene elastomers are resins obtained by removing the polypropylene elastomers from the above-mentioned polypropylene resins.

[0035] As a polypropylene-based resin other than polypropylene elastomer, it is preferable to use block polypropylene from the viewpoint of obtaining interlayer adhesion with the oxygen-absorbing layer.

[0036] The density of polypropylene-based resins other than polypropylene elastomers is 0.880 g / cm³. ３ Above, 0.885g / cm ３ Above, 0.890g / cm ３ Above, or 0.895 g / cm³ ３ Above, or 0.920 g / cm³ ３ The above is sufficient, and also 0.950 g / cm³ ３ Below, 0.940g / cm ３ Below, 0.930g / cm ３ Below, 0.925g / cm ３ Below, 0.920g / cm ３ Below, 0.915g / cm ３ Below, 0.910g / cm ３ The following, or 0.905 g / cm³ ３ The following is acceptable:

[0037] The content of polypropylene-based resins other than polypropylene elastomer in the first surface resin layer may be 45% by mass or more and 95% by mass or less with respect to the mass of the first surface resin layer. This content may be 45% by mass or more, 50% by mass or more, 55% by mass or more, 60% by mass or more, or 65% by mass or more, 70% by mass or more, and may also be 95% by mass or less, 90% by mass or less, 85% by mass or less, 80% by mass or less, or 75% by mass or less.

[0038] <Oxygen Absorption Layer> The oxygen absorption layer is a layer that is fused to the first and second surface resin layers. The oxygen absorption layer contains at least iron powder and polypropylene resin.

[0039] The oxygen-absorbing layer may further contain polypropylene elastomer, particularly the polypropylene elastomer mentioned with respect to the first surface resin layer. In this case, the elasticity provided by the polypropylene elastomer allows it to absorb external forces such as external pressure, thereby providing good physical strength.

[0040] In particular, in this embodiment, good oxygen absorption can be obtained when the polypropylene elastomer content is 40% by mass or more relative to the total mass of the resin components constituting the oxygen absorption layer. Although we do not wish to be bound by theory, polypropylene elastomer, density 0.900 g / cm³ ３ When polypropylene elastomer is included in small amounts, it is thought that the small amount of polypropylene elastomer will localize, causing steric interference and resulting in low oxygen absorption. On the other hand, when it is included at a concentration of 40% by mass or more relative to the total mass of the resin components constituting the oxygen absorption layer, the polypropylene elastomer will be uniformly dispersed, and the effect of bulkiness due to the low density will become dominant, resulting in high oxygen absorption.

[0041] The thickness of the oxygen absorption layer may be 5 to 100 μm. This thickness may be 5 μm or more, 7 μm or more, 10 μm or more, 12 μm or more, 15 μm or more, 18 μm or more, 20 μm or more, 23 μm or more, 25 μm or more, or 28 μm or more, and may also be 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, or 33 μm or less.

[0042] The iron powder content in the oxygen absorption layer may be 10 to 80% by mass relative to the mass of the oxygen absorption layer. This content may be 10% by mass or more, 13% by mass or more, 15% by mass or more, 20% by mass or more, or 23% by mass or more, and may also be 80% by mass or less, 75% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, 55% by mass or less, 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 33% by mass or less.

[0043] The oxygen absorption layer may further contain an oxidation accelerator. In this case, the content of the oxidation accelerator may be 1 to 30% by mass relative to the mass of the iron powder. This content may be 1% or more by mass, 3% or more by mass, 5% or more by mass, 7% or more by mass, or 10% or more by mass, and may also be 30% or less by mass, 25% or less by mass, 20% or less by mass, or 15% or less by mass, relative to the mass of the iron powder.

[0044] The oxygen absorption layer may further contain other oxygen absorbers besides iron powder. In this case, the content of the other oxygen absorbers may be 10% by mass or less, 7% by mass or less, 5% by mass or less, 3% by mass or less, 1% by mass or less, or 0% by mass, relative to the mass of the oxygen absorption layer.

[0045] The oxygen absorption layer may further contain a white pigment to mitigate the black color derived from the iron powder contained within it. Examples of white pigments that can be used include metal oxides such as titanium dioxide.

[0046] The content of the white pigment in the oxygen absorption layer may be, for example, 1 to 25% by mass relative to the mass of the oxygen absorption layer. This content may be 1% by mass or more, 2% by mass or more, 3% by mass or more, 4% by mass or more, or 5% by mass or more, and may also be 25% by mass or less, 23% by mass or less, 20% by mass or less, 15% by mass or less, 12% by mass or less, or 10% by mass or less.

[0047] (Iron powder) As iron powder, for example, reduced iron powder, sprayed iron powder, activated iron powder, etc. can be used. Such iron powder can be those that are commercially available as masterbatches.

[0048] (Polypropylene resin) As the polypropylene resin, the polypropylene resins listed for the first surface resin layer can be used. In particular, as such a polypropylene resin, the polypropylene resins listed for the first surface resin layer can be used.

[0049] (Polypropylene elastomer) As the polypropylene elastomer, those listed for the first surface resin layer can be used.

[0050] The polypropylene elastomer content may be 40% by mass or more relative to the mass of the resin components constituting the oxygen absorption layer. This content may be 40% by mass or more, 45% by mass or more, 50% by mass or more, 55% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, 75% by mass or more, or 80% by mass or more, and may also be 100% by mass or less, 95% by mass or less, 92% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, or 60% by mass or less. From the viewpoint of oxygen absorption and physical strength, it is preferable that the polypropylene elastomer content be 80% by mass or more relative to the mass of the resin components constituting the oxygen absorption layer.

[0051] Furthermore, the polypropylene elastomer content may be more than 20% by mass, 22% or more by mass, 25% or more by mass, or 28% or more by mass, relative to the mass of the oxygen absorption layer, and may also be 70% or less by mass, 65% or less by mass, 60% or less by mass, 55% or less by mass, or 52% or less by mass.

[0052] (Polyolefin resins other than polypropylene resins) As polyolefin resins other than polypropylene resins, for example, polyethylene resins can be used.

[0053] In this specification, polyethylene resins are resins containing more than 50 mol%, 60 mol%, 70 mol%, or 80 mol% of repeating ethylene groups in the main chain of the polymer, and are selected from the group consisting of, for example, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene-vinyl acetate copolymer (EVA), carboxylic acid-modified polyethylene, carboxylic acid-modified ethylene vinyl acetate copolymer, ionomers, derivatives thereof, and mixtures thereof.

[0054] (Oxidation accelerators) As oxidation accelerators, alkali metal chlorides such as sodium chloride, alkaline earth metal oxides such as calcium chloride and magnesium chloride can be used.

[0055] (Other oxygen absorbers) Other oxygen absorbers besides iron powder include iron-based compounds such as ferrous oxide and ferrous salts, metal halides such as calcium chloride and magnesium chloride, and metal oxides such as cerium oxide.

[0056] <Second Surface Resin Layer> The second surface resin layer is a surface resin layer fused to the oxygen absorption layer on the side opposite to the first surface resin layer. The second surface resin layer may contain polypropylene elastomer. In particular, if the first surface resin layer does not contain polypropylene elastomer, the second surface resin layer contains polypropylene elastomer.

[0057] The second surface resin layer can be a layer used as a sealant layer. In other words, in the packaging laminate mentioned below, it can be the outermost layer.

[0058] For the polypropylene elastomer and polypropylene-based resin constituting the second surface resin layer, refer to the description relating to the first surface resin layer.

[0059] As long as at least one of the first and second surface resin layers contains polypropylene elastomer, the resin constituting the second surface resin layer may be different from or the same as the resin constituting the first surface resin layer. For example, if the first surface resin layer contains polypropylene elastomer, the second surface resin layer may consist only of homopolypropylene, random polypropylene, or block polypropylene, or it may consist of a mixture of these and polypropylene elastomer.

[0060] The thickness of the second surface resin layer can be determined by referring to the thickness of the first surface resin layer. The thickness of the second surface resin layer may be different from or the same as the thickness of the first surface resin layer, but it is preferable that it be greater than 10 μm from the viewpoint of heat seal strength, and less than 50 μm from the viewpoint of increasing the oxygen absorption rate.

[0061] <Laminate for Packaging> The laminate for packaging 20 of the present invention has the above-mentioned oxygen-absorbing sealant film 10 and a base layer 22, wherein the base layer 22 is laminated on the first surface resin layer 12.

[0062] The adhesion between the base material layer 22 and the first surface resin layer 12 may be achieved, for example, via an adhesive layer 24.

[0063] The packaging laminate of the present invention may be, for example, a packaging bag laminate, a laminate tube laminate, or a lid material laminate.

[0064] In particular, when the packaging laminate of the present invention is a laminate for a laminate tube, it is preferable from the viewpoint of obtaining a laminate tube to have another sealant layer on the side opposite to the second surface resin layer. The resin constituting the second surface resin layer can be used as the other sealant layer.

[0065] <Base Layer> The base layer may consist of a flexible base layer. The base layer may also have a barrier layer. The flexible base layer and the barrier layer may each consist of one or more layers, and these layers may be laminated with an adhesive layer in between. This lamination may be carried out by known methods, such as dry lamination, extrusion lamination, hot melt, or non-solvent lamination.

[0066] Furthermore, a printed layer may be laminated on at least a portion of the above-mentioned layers that constitute the base material layer. This printed layer may be printed by gravure printing, flexographic printing, or the like.

[0067] (Flexible base material layer) The flexible base material layer refers to a base material layer having flexible properties, particularly a base material layer with a thickness of 100 μm or less. The thickness of the flexible base material layer is not particularly limited as long as it does not impair its flexible properties, and may be, for example, 7 μm or more and 100 μm or less. This thickness may be 7 μm or more, or 10 μm or more, and may also be 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

[0068] Such a base material layer can be a flexible resin base material layer, a flexible paper base material layer, or the like.

[0069] (Flexible base layer: Flexible resin base layer) The flexible resin base layer may be composed of a thermoplastic resin with excellent impact resistance, abrasion resistance, etc., such as a vinyl resin, polyester resin, or polyamide resin. The flexible resin base layer may be a single layer or a laminate.

[0070] Examples of vinyl resins include polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polychlorotrifluoroethylene, polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polytetrafluoroethylene, and polyacrylonitrile (PAN).

[0071] Examples of polyester resins include polyethylene terephthalate (PET) and polybutylene terephthalate.

[0072] Examples of polyamide resins include nylon (registered trademark) 6, nylon MXD6, and other types of nylon.

[0073] Furthermore, as the laminate of the soft resin substrate layer, a known laminate of PVF / PET / PVF, such as TPT, can be used.

[0074] From the viewpoint of mechanical strength of the packaging laminate, the thickness of the soft resin substrate layer is preferably 7 μm or more, or 10 μm or more. This thickness may be 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

[0075] The resins constituting the flexible resin base layer may be not just one type, but a blend of two or more types, and additives to impart functionality may be included as needed.

[0076] Furthermore, it is preferable that the flexible resin base layer be made from a pre-formed film. The film that becomes the flexible resin base layer can be any film formed from the above-mentioned resin, and may be unstretched, uniaxially or biaxially stretched, or otherwise. Among these, a biaxially stretched film is preferred.

[0077] (Flexible base material layer: Flexible paper base material layer) Coated paper, art paper, etc. may be used as the flexible paper base material layer.

[0078] The basis weight of the paper constituting the soft paper base layer is 10 g / m². ２ Above, 30g / m ２ or more, or 50 g / m² ２ The above is sufficient, and also 200 g / m ２ Below, 150g / m ２ The following, or 100 g / m ２ The following is acceptable:

[0079] (Barrier layer) As the barrier layer, a material can be used that can suppress the permeation of moisture, organic gases, and inorganic gases between the substrate layer and the second surface resin layer, and / or prevent oxygen from permeating from the outside and deactivating the oxygen absorption layer, and / or protect the substance located on the second surface resin layer side.

[0080] Examples of such barrier layers include single metal foil layers such as copper foil and aluminum foil, alloy foil layers such as stainless steel foil, inorganic vapor-deposited films such as silica vapor-deposited films, alumina vapor-deposited films, aluminum vapor-deposited films, or silica-alumina binary vapor-deposited films, barrier resin layers such as ethylene-vinyl alcohol copolymer (EVOH), cyclic olefin polymer (COP), or cyclic olefin copolymer (COC), or organic coating films such as polyvinylidene chloride coating films, polychlorotrifluoroethylene coating films, or polyvinylidene fluoride coating films.

[0081] In particular, among the barrier layers described above, the inorganic vapor-deposited film, the barrier resin layer, and the organic coating film can function as transparent barrier layers.

[0082] When an inorganic vapor-deposited film or an organic coating film is used as the barrier layer, the thickness of the barrier layer is preferably 100 nm or more, 200 nm or more, 300 nm or more, 500 nm or more, 700 nm or more, or 1 μm or more from the viewpoint of ensuring strength and barrier properties, and is preferably 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less from the viewpoint of reducing the overall thickness of the packaging laminate.

[0083] When a metal foil layer or a barrier resin layer is used as the barrier layer, the thickness of the barrier layer is preferably 5 μm or more, or 7 μm or more, from the viewpoint of ensuring strength and barrier properties. Furthermore, a thickness of 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less is preferable from the viewpoint of reducing the overall thickness of the packaging laminate.

[0084] (Adhesive layer) For the adhesive layer, for example, a dry laminating adhesive or a hot laminating adhesive can be used.

[0085] <Other Layers> The packaging laminate of the present invention may have other optional layers. Examples of other layers include an adhesive layer located between the base material layer and the first surface resin layer, and an anchor coat layer.

[0086] 《Packaging Bag》 The packaging container of the present invention has the above-described laminated packaging material.

[0087] The packaging bag of the present invention may be a packaging bag containing contents that are contained in the packaging container.

[0088] The packaging container of the present invention may be a packaging bag or a laminated tube.

[0089] In particular, the packaging bag of the present invention comprises one or more of the above-mentioned packaging laminates, and a portion of one or more of the packaging laminates is heat-sealed to other portions of the packaging laminates or to another film, thereby forming a bag. Here, the other film may be another packaging laminate, or to any other film other than a packaging laminate.

[0090] Herein, one embodiment of the packaging bag of the present invention may be a bag having at least a peripheral seal portion in which two films are heat-sealed with their peripheries facing each other. The peripheral seal portion can be obtained by a method that includes placing two films facing each other and heat-sealing at least a portion of the peripheries of these films. Examples of such packaging bags include standing pouches, retort pouches, spout pouches, and four-sided sealed bags.

[0091] Furthermore, one embodiment of the packaging bag of the present invention may be a bag having at least a back seal portion that is heat-sealed at both opposite ends of a single film. This back seal portion can be obtained by a method that includes overlapping the sealant layers at both opposite ends of a single film and heat-sealing them to form a tube. Examples of such packaging bags include three-side seal bags, gusset bags, pillow bags, and the like.

[0092] Furthermore, the packaging bag of the present invention may be an inner container that constitutes a bag-in-box, that is, a container that combines a flexible inner container with an outer container that is generally made of corrugated cardboard.

[0093] <Other Films> Other films are not particularly limited and may include, for example, transparent barrier films. Transparent barrier films may have, for example, the transparent barrier layer, the flexible resin substrate layer, and the sealant layer described above. Furthermore, at least a portion of the transparent barrier film described above may have a printed layer.

[0094] <Contents> The contents may be, for example, food, medicine, electronic components, etc.

[0095] Foods may include, for example, liquid foods such as beverages, cooking oils, soups, and liquid seasonings; solid foods such as confectionery, rice, and bread; semi-solids such as jelly, tofu, miso, mayonnaise, jam, cream, and paste; and powders and granules such as powdered soup.

[0096] Pharmaceuticals may include, for example, medicines, toiletries, and cosmetics.

[0097] Pharmaceuticals may be solid drugs such as tablets and capsules, liquid drugs such as intravenous solutions, or semi-solid drugs such as transdermal agents.

[0098] Toiletries products may include, for example, shampoo, conditioner, and detergent.

[0099] Cosmetics can include, for example, lotions, moisturizers, and toners.

[0100] Lid Material The lid material of the present invention has the above-described packaging laminate.

[0101] The lid material of the present invention may have a tab for pinching and pulling up when opening.

[0102] The lid material of the present invention may be a lid material for heat-sealing a polypropylene resin surface of a container.

[0103] The present invention will be specifically described by examples and comparative examples, but the present invention is not limited thereto.

[0104] <Preparation of Oxygen-Absorbing Sealant Film> <Example 1> Using a T-die molding machine, a two-type, three-layer oxygen-absorbing sealant film was obtained by co-extrusion T-die method, having a first surface resin layer with a thickness of 20 μm, an oxygen-absorbing layer with a thickness of 30 μm, and a second surface resin layer with a thickness of 20 μm.

[0105] The first and second surface resin layers consist of 95 parts by mass of block polypropylene (bPP, density 0.900 g / cm³). ３ , melting point 162°C, MFR 2.0 g / 10 min (230°C)) and 5 parts by mass of polypropylene elastomer (PP-el, density 0.866 g / cm³) ３ A resin composition was used which was mixed with MFR 6.0 g / 10 min (230°C). As the oxygen absorption layer, a resin composition was used which was mixed with 50 parts by mass of a polypropylene-based iron powder-containing masterbatch (containing iron powder MB, 50-60% by mass of iron powder, 10-20% by mass of white pigment, and 10-20% by mass of polypropylene-based resin) and 50 parts by mass of the above-mentioned polypropylene-based elastomer.

[0106] <Examples 2-14 and Comparative Examples 1-2> Packaging laminates for Examples 2-14 and Comparative Examples 1-2 were prepared in the same manner as in Example 1, except that the types and content of each component were changed as shown in Table 1.

[0107] <Evaluation> <Film Forming Properties> The film forming properties of the oxygen-absorbing sealant films obtained by the co-extrusion T-die method were evaluated by visually observing their appearance. In addition, the oxygen-absorbing sealant films obtained by the co-extrusion inflation method for Examples 4, 7 and 10, and Comparative Example 1 were also evaluated in the same manner. The evaluation criteria are as follows: A: Film formation was successful without any problems. B: Film formation was successful, but wrinkles were observed. C: Blocking occurred, making film formation difficult.

[0108] <Oxygen Absorption Amount> (1) A nonwoven fiber fabric was placed in a resealable plastic bag, and a window-shaped cut was made on one side of the plastic bag. 10 mL of pure water was poured into the nonwoven fabric through the window to create a water-absorbing cotton pad. (2) A rubber sheet was attached to the edge of the opening of an aluminum foil laminated film bag (internal dimensions: 290 mm x 200 mm, three-sided bag), and a sealing needle was inserted into the rubber sheet. The two oxygen-absorbing sealant films and the water-absorbing cotton pad (containing 10 mL of water) were then attached in positions where they would not directly contact each other inside the bag, and the opening was heat-sealed. (3) A syringe was connected to the sealing needle, and the air inside the aluminum foil laminated film bag was removed. (4) 500 mL of air was inserted through the sealing needle to seal the bag. (5) The sealing needle was removed, and the area where the sealing needle was inserted was heat-sealed to isolate and seal the bag, obtaining a sealed bag. (6) The sealed bag was left to stand in a constant temperature bath at 40°C. (7) After 7 days, the oxygen concentration inside the aluminum foil laminated film bag was measured. The measurement was performed by attaching an adhesive rubber plate to the sealed bag and inserting the measuring needle of a diaphragm-type galvanic cell oxygen sensor, PackReader (RO105L, Iijima Electronics Industry Co., Ltd.), into the bag through the adhesive rubber plate. (8) The amount of oxygen absorbed by the oxygen-absorbing sealant film was calculated using the following formula: Oxygen absorbed (mL) = (Oxygen concentration in the atmosphere - Oxygen concentration inside the bag) / (100 - Oxygen concentration inside the bag) × Amount of sealed air (mL)

[0109] <Bag Breaking Strength> A laminate was prepared as the base layer by dry laminating polyethylene terephthalate film, aluminum foil, and nylon film in that order. The nylon film side of this base layer was laminated to the first surface resin layer of the obtained oxygen-absorbing sealant film by dry lamination to obtain a packaging laminate. Two pieces of this were cut to an outer size of 100 mm x 100 mm. The second surface resin layers of these packaging laminates were placed facing each other and heat-sealed with a seal width of 10 mm to create a three-side seal bag.

[0110] 70g of water was sealed into the prepared three-sided bag, and the opening was heat-sealed to remove any air, thereby creating a packaging bag.

[0111] The resulting packaging bag was subjected to pressure using upper and lower metal plates large enough to cover the entire bag, and the strength at which the bag ruptured was defined as the rupture strength.

[0112] Table 1 shows the configurations and evaluation results of the examples and comparative examples.

[0113]

[0114] Table 1 shows that the oxygen-absorbing sealant films of Examples 1 to 12, in which the first or second surface resin layer contains polypropylene elastomer at a content of 5% by mass or more, achieve significantly improved physical strength without significantly impairing oxygen absorption compared to the oxygen-absorbing sealant film of Comparative Example 1, which uses the same oxygen-absorbing layer but whose first and second surface resin layers do not contain polypropylene elastomer. A similar trend can be observed when comparing the oxygen-absorbing sealant films of Examples 13 and 14, which have a modified oxygen-absorbing layer configuration, with the oxygen-absorbing sealant film of Comparative Example 2.

[0115] 10 Oxygen-absorbing sealant film 12 First surface resin layer 14 Oxygen-absorbing layer 16 Second surface resin layer 20 Laminate for packaging 22 Base layer 24 Adhesive layer

Claims

1. An oxygen-absorbing sealant film having at least a first surface resin layer, an oxygen-absorbing layer, and a second surface resin layer in this order, wherein the first surface resin layer and the second surface resin layer contain a polypropylene resin, and the oxygen-absorbing layer contains at least iron powder and a polypropylene resin, and satisfies at least one of the following (i) and (ii): (i) The first surface resin layer has a density of 0.900 g / cm³ ３ (ii) The second surface resin layer contains the following polypropylene elastomer, and the content of the polypropylene elastomer in the first surface resin layer is 5% by mass or more relative to the mass of the first surface resin layer, and / or (ii) the density of the second surface resin layer is 0.900 g / cm³ ３ An oxygen-absorbing sealant film containing the following polypropylene elastomer, wherein the content of the polypropylene elastomer in the second surface resin layer is 5% by mass or more relative to the mass of the second surface resin layer.

2. The oxygen-absorbing sealant film according to claim 1, wherein the content of the polypropylene elastomer in the first surface resin layer is 55% by mass or less, and / or the content of the polypropylene elastomer in the second surface resin layer is 55% by mass or less.

3. The oxygen-absorbing sealant film according to claim 1, wherein the first surface resin layer and the second surface resin layer further contain block polypropylene.

4. The oxygen-absorbing sealant film according to any one of claims 1 to 3, wherein the oxygen-absorbing layer contains a polypropylene elastomer.

5. The oxygen-absorbing sealant film according to claim 4, wherein the content of the polypropylene elastomer in the oxygen-absorbing layer is 40% by mass or more with respect to the total mass of the resin components constituting the oxygen-absorbing layer.

6. An oxygen-absorbing sealant film according to any one of claims 1 to 5, wherein the thickness is 100 μm or less.

7. An oxygen-absorbing sealant film according to any one of claims 1 to 6, which is an inflation film.

8. A packaging laminate comprising an oxygen-absorbing sealant film according to any one of claims 1 to 7, and a base layer, wherein the base layer is laminated on the first surface resin layer.

9. A packaging bag having the packaging laminate described in claim 8.

10. A lid material having the packaging laminate described in claim 8.

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