Resin film and package

Abstract

To provide a new resin film which enables production of an EP type package from a packaging material having an easy peel (EP) layer and other packaging material, using a resin film having the EP layer, and improves peeling feeling of the packaging material having the EP layer, when the package is opened.SOLUTION: A resin film has an EP layer having a mass ratio of [content of polyethylene-based resin]:[content of polypropylene-based resin] of 60:40 to 30:70, wherein using a test piece manufactured by heating and sealing the EP layer in the resin film and the polyethylene film while the MD is aligned, peeling strength X (MD) when the polyethylene film is peeled in the MD direction from the resin film is 0.5 to 5 N / 15 mm, using the separately manufactured test piece, peeling strength X (TD) when the polyethylene film is peeled in the TD direction from the resin film is 1 to 5 N / 15 mm, and peeling strength X (TD) / peeling strength X (MD) is 0.9 to 2.5.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin film and a packaging body. [Background technology]

[0002] A resin film having an easy-peel layer (easy-peel sealant layer) can be used as one packaging material by itself or a molded product thereof, and heat-sealed to another packaging material, which is another resin film or a molded product thereof, to form a package that can be easily opened at the desired time. Such easy-peel packages are widely used, mainly for food applications, due to their high convenience. A typical example of a resin film having an easy-peel layer is a laminate film having a laminate structure of two or more layers, including an easy-peel layer and other layers.

[0003] An example of an easy-peel layer is a layer containing two incompatible resins, and polyethylene-based resin and polypropylene-based resin are commonly used as the two incompatible resins. When a package is produced using a resin film having such an easy-peel layer, cohesive failure occurs in the easy-peel layer when the package is opened. Known easy-peel layers include those in which the polyethylene-based resin content is about 2.3 times or more by mass relative to the polypropylene-based resin content (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-136151 Summary of the Invention [Problem to be solved by the invention]

[0005] When peeling a packaging material having an easy-peel layer from another packaging material to open an easy-peel type packaging, it is desirable that the peeling feel be good. Good peeling means that the packaging material has an appropriate peel strength and the packaging material having the easy-peel layer can be peeled from the other packaging material smoothly and without any discomfort.

[0006] However, when conventional resin films having an easy-peel layer, such as the resin film disclosed in Patent Document 1, are used, there is room for improvement in the peeling feel of the packaging material having an easy-peel layer when opening the package.

[0007] The present invention addresses the problem of providing a novel resin film having an easy-peel layer, which can be used to produce an easy-peel type package from one packaging material having an easy-peel layer and another packaging material using the resin film, and which provides a good peeling feel of the packaging material having the easy-peel layer when the package is opened. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention employs the following configuration. [1] A resin film having an easy-peel layer as the outermost layer, the easy-peel layer contains a polyethylene-based resin and a polypropylene-based resin, In the easy-peel layer, the mass ratio of [content of polyethylene-based resin (parts by mass)]:[content of polypropylene-based resin (parts by mass)] is 60:40 to 30:70, The easy-peel layer in the resin film and the polyethylene film were heat-sealed with their MDs aligned under conditions of a sealing temperature of 140°C, a sealing pressure of 0.15 MPa, and a sealing time of 2 seconds, and then a 15 mm wide region was cut from the heat-sealed region to prepare a first test piece whose length direction aligned with the MD. The polyethylene film was peeled from the resin film in the same direction as the MD of the first test piece at a peel rate of 200 mm / min in accordance with JIS Z 0238:1998 to measure the peel strength X(MD). A 15 mm wide region was cut from the heat-sealed region to prepare a second test piece whose length direction aligned with a direction perpendicular to the MD. The polyethylene film was peeled from the resin film in the same direction as the TD of the second test piece at a peel rate of 200 mm / min in accordance with JIS Z 0238:1998 to measure the peel strength X(TD). The peel strength X (MD) is 0.5 to 5 N / 15 mm, The peel strength X(TD) is 1 to 5 N / 15 mm, A resin film having a value of [peel strength X (TD)] / [peel strength X (MD)] of 0.9 to 2.5.

[0009] [2] The resin film according to [1], further comprising a flexible layer adjacent to the easy-peel layer. [3] The resin film according to [2], wherein the flexible layer contains a polyolefin resin. [4] The resin film according to any one of [1] to [3], wherein the ratio of the thickness of the easy-peel layer to the thickness of the resin film is 5 to 10%. [5] The resin film according to any one of [1] to [4], further comprising a pinhole-resistant layer.

[0010] [6] The resin film according to any one of [1] to [5], further comprising an oxygen barrier layer. [7] The resin film according to any one of [1] to [6], further comprising an outer layer. [8] A packaging body made using the resin film according to any one of [1] to [7]. [9] The packaging body described in [8], wherein the packaging body contains food. [Effects of the Invention]

[0011] According to the present invention, there is provided a novel resin film having an easy-peel layer, which is used to produce an easy-peel type packaging body from one packaging material having an easy-peel layer and another packaging material, and which provides a good peeling feel of the packaging material having the easy-peel layer when the packaging body is opened. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of a resin film according to one embodiment of the present invention. [Figure 2] 1 is a cross-sectional view schematically illustrating an example of a packaging body according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] <<Resin film>> In one embodiment of the present invention, the resin film includes an easy-peel layer as an outermost layer, the easy-peel layer containing a polyethylene-based resin and a polypropylene-based resin, and in the easy-peel layer, a mass ratio of [a content (parts by mass) of the polyethylene-based resin]:[a content (parts by mass) of the polypropylene-based resin] is 60:40 to 30:70, The easy-peel layer in the resin film and the polyethylene film were heat-sealed under conditions of a sealing temperature of 140°C, a sealing pressure of 0.15 MPa, and a sealing time of 2 seconds, with their MDs aligned, and then a 15 mm wide region was cut from the heat-sealed region to prepare a first test piece whose length direction aligned with the MD. In accordance with JIS Z 0238:1998, the polyethylene film was peeled from the resin film in the same direction as the MD at a peel speed of 200 mm / min to measure the peel strength X(MD). A 15 mm wide region was cut from the heat-sealed region to prepare a second test piece whose length direction aligned with the direction perpendicular to the MD. In accordance with JIS Z When the polyethylene film is peeled from the resin film in the same direction as the TD at a peel speed of 200 mm / min in accordance with JIS K 0238:1998 and the peel strength X(TD) is measured, the peel strength X(MD) is 0.5 to 5 N / 15 mm, the peel strength X(TD) is 1 to 5 N / 15 mm, and the value of [peel strength X(TD)] / [peel strength X(MD)] is 0.9 to 2.5. The MD is the direction in which the resin flows (Machine Direction), and the TD is the direction perpendicular to the MD (Transverse Direction).

[0014] Using the resin film of this embodiment, one packaging material with an easy-peel layer is prepared, and another packaging material is prepared separately, and the one packaging material and the other packaging material are heat-sealed to produce an easy-peel type packaging body.

[0015] In this specification, unless otherwise specified, the mere expression "resin film" means the resin film of the present embodiment described above.

[0016] <[Polyethylene resin content (parts by mass)]:[Polypropylene resin content (parts by mass)]> In the easy-peel layer of the resin film of this embodiment, the mass ratio of [polyethylene resin content (parts by mass)]:[polypropylene resin content (parts by mass)] is 60:40 to 30:70. By satisfying these conditions, an easy-peel type package is produced from one packaging material having an easy-peel layer using the resin film and the other packaging material, and the packaging material having the easy-peel layer provides a good peeling feel when the package is opened.

[0017] As a result of the investigation, it was found that when the package is opened, regardless of the direction in which one of the packaging materials is peeled, as long as the peel strength is not too high and is stable within an appropriate range, the peeling feel of the packaging material tends to be felt to be good. The resin film of the present embodiment certainly exhibits such peel strength and achieves a good peeling feel.

[0018] In the easy-peel layer, the lower the polyethylene resin content and the higher the polypropylene resin content, within an appropriate range, the better the peeling feel when opening the package. From this perspective, the mass ratio of [polyethylene resin content (parts by mass)]:[polypropylene resin content (parts by mass)] may be any of 55:45 to 30:70, 48:52 to 30:70, and 43:57 to 30:70.

[0019] <Peel strength X (MD)> When preparing the first test piece to be used for measuring the peel strength X (MD), first, the easy-peel layer in the resin film and the polyethylene film are matched in MD (which is equivalent to matching in TD), and then heat-sealed under the conditions of a sealing temperature of 140°C, a sealing pressure of 0.15 MPa, and a sealing time of 2 seconds to prepare a heat-sealed body. Next, a 15 mm wide area is cut from the heat-sealed portion of the heat-sealed product, with the length direction of this area aligned with the MD of the easy-peel layer and the polyethylene film. In this way, the first test piece can be prepared. When measuring the peel strength X (MD), the polyethylene film is peeled from the resin film in the length direction of the first test piece (which is equivalent to the MD of the easy-peel layer and the polyethylene film).

[0020] As the polyethylene film, commercially available products such as SUMILITE (registered trademark) CEL series films such as "SUMILITE (registered trademark) CEL-9200A," "SUMILITE (registered trademark) CEL-4230A," and "SUMILITE (registered trademark) CEL-7901A" (all manufactured by Sumitomo Bakelite Co., Ltd.) can be used. The thickness of the polyethylene film is preferably 50 to 70 μm, and may be, for example, 60 μm. The polyethylene film may have a heat seal surface with the resin film made of polyethylene.

[0021] The peel strength X(MD) is 0.5 to 5 N / 15 mm, preferably 0.5 to 3.5 N / 15 mm, and more preferably 0.5 to 2 N / 15 mm. For example, it may be either 0.5 to 1 N / 15 mm or 1 to 2 N / 15 mm. When the peel strength X(MD) is equal to or greater than the lower limit, unintended peeling between one packaging material having an easy-peel layer and the other packaging material in the package is strongly suppressed. In other words, unintended opening of a package obtained using the resin film is strongly suppressed. When the peel strength X(MD) is equal to or less than the upper limit, the package can be easily opened at the intended time.

[0022] In this specification, unintended opening of a package does not mean intentional opening of the package by a user in order to remove the packaged item from the package, but rather accidental opening of the package when the user wishes to maintain the package in its original state. Unintended peeling of the packaging material means peeling of the packaging material that leads to such unintended opening of the package.

[0023] The peel strength X(MD) can be adjusted by adjusting the type and content of the components contained in the easy-peel layer. In particular, the peel strength X(MD) can be easily adjusted by adjusting the mass ratio of [polyethylene resin content (parts by mass)] to [polypropylene resin content (parts by mass)]. For example, the peel strength X(MD) tends to increase by relatively increasing the polypropylene resin content.

[0024] <Peel strength X (TD)> When preparing the second test piece for measuring the peel strength X (TD), a 15 mm wide area was cut from the heat-sealed portion of the heat-sealed body prepared in the same manner as in the preparation of the first test piece. At this time, the length direction of this area was aligned with the TD (i.e., the direction perpendicular to the MD) of the easy-peel layer and the polyethylene film. This allowed the second test piece to be prepared. When measuring the peel strength X(TD), the polyethylene film is peeled from the resin film in the length direction of the second test piece (which is the same as the TD between the easy-peel layer and the polyethylene film).

[0025] The peel strength X(TD) is 1 to 5 N / 15 mm, preferably 1 to 3.5 N / 15 mm, and more preferably 1 to 2.5 N / 15 mm, and may be, for example, either 1 to 1.8 N / 15 mm or 1.8 to 2.5 N / 15 mm. When the peel strength X(TD) is equal to or greater than the lower limit, unintended opening of a package obtained using the resin film is strongly suppressed. When the peel strength X(TD) is equal to or less than the upper limit, the package can be easily opened at the intended time.

[0026] The peel strength X(TD) can be adjusted in the same way as the peel strength X(MD). For example, by relatively increasing the content of polypropylene resin, the peel strength X(TD) tends to increase.

[0027] <[Peel strength X (TD)] / [Peel strength X (MD)]> The value of [peel strength X(TD)] / [peel strength X(MD)] is 0.9 to 2.5, and since this condition is satisfied and the anisotropy of the peel strength in MD and TD is low, when the package is opened, the packaging material has a good peeling feel regardless of the peel direction of one of the packaging materials with the easy-peel layer. The value of [peel strength X(TD)] / [peel strength X(MD)] is preferably 0.9 to 2.2, more preferably 0.9 to 1.9, and may be, for example, any of 0.9 to 1.62 and 0.9 to 1.55. The closer the value of [peel strength X(TD)] / [peel strength X(MD)] is to 1, the better the peeling feel of the packaging material becomes.

[0028] In the resin film of this embodiment, not only are the peel strength X(MD) and the peel strength X(TD) each set within a specific range, but also the value of [peel strength X(TD)] / [peel strength X(MD)] is set within a specific range, thereby providing a good peel feel for the packaging material. If any of these three conditions is not met, the peel feel of the packaging material will be poor.

[0029] <Example of resin film> FIG. 1 is a cross-sectional view schematically illustrating an example of the resin film of the present embodiment. In addition, the figures used in the following explanation may show enlarged essential parts for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality.

[0030] The resin film 1 shown here has an easy-peel layer 11 as one of its outermost layers (one of the outermost layers). The resin film 1 further has an outer layer 15 as the other outermost layer (the other outermost layer), and a flexible layer 12 adjacent to the easy-peel layer 11 and arranged on the outer layer 15 side. Resin film 1 further includes an oxygen barrier layer 13 and a pinhole resistant layer 14 disposed between flexible layer 12 and outer layer 15 in this order from the flexible layer 12 side toward the outer layer 15 side. The resin film 1 further includes a first adhesive layer 161 disposed between the flexible layer 12 and the oxygen barrier layer 13, and a second adhesive layer 162 disposed between the pinhole-resistant layer 14 and the outer layer 15. That is, the resin film 1 is constructed by laminating an easy-peel layer 11, a flexible layer 12, a first adhesive layer 161, an oxygen barrier layer 13, a pinhole-resistant layer 14, a second adhesive layer 162 and an outer layer 15 in this order in the thickness direction.

[0031] The easy-peel layer 11 in the resin film 1 contains a polyethylene-based resin and a polypropylene-based resin, and in the easy-peel layer 11, the mass ratio of [polyethylene-based resin content (parts by mass)]:[polypropylene-based resin content (parts by mass)] is 60:40 to 30:70. The peel strength X(MD) of the first test piece made from a heat-sealed body between the easy-peel layer 11 in the resin film 1 and the polyethylene film is 0.5 to 5 N / 15 mm, and the peel strength X(TD) of the second test piece made from the heat-sealed body is 1 to 5 N / 15 mm, and the value of [peel strength X(TD)] / [peel strength X(MD)] is 0.9 to 2.5.

[0032] The flexible layer 12 is a layer for improving the flexibility of the resin film 1. For example, in a package obtained by heat sealing using such a resin film 1, the seal strength is stabilized. The oxygen barrier layer 13 inhibits the permeation of oxygen gas and imparts oxygen barrier properties to the resin film 1. The pinhole-resistant layer 14 is a layer for suppressing the occurrence of pinholes in the resin film 1. The outer layer 15 has rigidity and is a layer for protecting the layers other than the outer layer 15 in the resin film 1 .

[0033] The surface 11b of the easy-peel layer 11 opposite to the flexible layer 12 is an exposed surface. When a package is produced by using the resin film 1 itself or a molded product thereof as one packaging material and heat-sealing this packaging material to another packaging material, the surface 11b of the easy-peel layer 11 becomes the heat-sealed surface with the other packaging material. The surface 15a of the outer layer 15 opposite to the easy-peel layer 11 side is an exposed surface. In the package manufactured as described above, the surface 15a of the outer layer 15 is also an exposed surface.

[0034] In this embodiment, the adhesive layer is a layer for adhering two adjacent layers together. In the resin film 1, the first adhesive layer 161 bonds the flexible layer 12 and the oxygen barrier layer 13 together, and the second adhesive layer 162 bonds the pinhole resistant layer 14 and the outer layer 15 together. In this specification, the first adhesive layer and the second adhesive layer may be collectively referred to as adhesive layers.

[0035] It is preferable that the easy-peel layer 11, flexible layer 12, first adhesive layer 161, oxygen barrier layer 13, pinhole-resistant layer 14, second adhesive layer 162 and outer layer 15 are all transparent, i.e., the resin film 1 is a transparent laminate film.

[0036] The resin film of this embodiment is not limited to the resin film 1 shown in Figure 1, and for example, some of the configuration of the resin film 1 may be changed, deleted, or added within the scope of the present invention.

[0037] For example, the resin film of the present embodiment may not include one or more layers selected from the group consisting of a flexible layer, an oxygen barrier layer, a pinhole-resistant layer, an outer layer, and an adhesive layer (for example, the first adhesive layer and the second adhesive layer). The layers included in the resin film of the present embodiment other than the easy-peel layer 11 can be appropriately selected depending on the application of the resin film. For example, when the resin film of this embodiment has an oxygen barrier layer and a pinhole-resistant layer, the stacking order of these layers from the easy-peel layer side to the outer layer side may be the pinhole-resistant layer and the oxygen barrier layer, rather than the oxygen barrier layer and the pinhole-resistant layer. For example, the resin film of this embodiment may or may not have other layers that do not fall under any of the easy-peel layer, flexible layer, oxygen barrier layer, pinhole-resistant layer, outer layer, and adhesive layer. Each layer constituting the resin film will now be described in more detail.

[0038] <Easy-peel layer> The easy-peel layer is a resin layer containing a polyethylene-based resin and a polypropylene-based resin. In this specification, unless otherwise specified, the term "polyethylene resin" refers to a polymer (resin component) having structural units derived from ethylene, and may be polyethylene (PE, for example, a homopolymer of ethylene) or an ethylene copolymer having structural units derived from ethylene and structural units derived from a monomer other than ethylene. In this specification, unless otherwise specified, the term "polypropylene-based resin" refers to a polymer (resin component) having structural units derived from propylene, and may be a homopolymer of propylene (homopolypropylene, hPP), or a propylene-based copolymer having structural units derived from propylene and structural units derived from a monomer other than propylene. However, among polyolefin resins (olefin copolymers) having structural units derived from ethylene and structural units derived from propylene, copolymers in which the number of structural units derived from propylene is greater than the number of structural units derived from ethylene are classified as propylene copolymers.

[0039] The easy-peel layer may or may not contain other components that do not fall into either the polyethylene-based resin or the polypropylene-based resin, as long as the effects of the present invention are not impaired.

[0040] Among the polyethylene-based resins contained in the easy-peel layer, examples of polyethylene (PE) include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene-catalyzed linear low-density polyethylene (mLLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE), with low-density polyethylene, linear low-density polyethylene, and metallocene-catalyzed linear low-density polyethylene being preferred.

[0041] In this specification, the density of low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and metallocene-catalyzed linear low density polyethylene (mLLDPE) is 0.910 g / cm 3 More than 0.945g / cm 3 is less than. The density of medium density polyethylene (MDPE) is 0.945 g / cm 3 More than 0.955g / cm 3 is less than. The density of high density polyethylene (HDPE) is 0.955 g / cm 3 That's all.

[0042] The melting point of the polyethylene resin contained in the easy-peel layer is preferably 100 to 135°C, more preferably 105 to 130°C, and even more preferably 110 to 130°C. When the melting point of the polyethylene resin is equal to or higher than the lower limit, the seal strength of the package is increased within an appropriate range. In this specification, the term "seal strength of the package" refers to the degree of resistance to unintended opening of an easy-peel package obtained by heat-sealing one package material having an easy-peel layer using the resin film of this embodiment with another package material. When the melting point of the polyethylene resin is equal to or lower than the upper limit, the effect of suppressing melting of the other package material when heat-sealing the one package material and the other package material is enhanced.

[0043] In this specification, the term "melting point" refers to a value measured in accordance with JIS K 7121 unless otherwise specified.

[0044] The melt flow rate (sometimes referred to as "MFR" in this specification) of the polyethylene resin contained in the easy-peel layer is preferably 1.0 to 4.0 g / 10 min, more preferably 1.5 to 3.5 g / 10 min, and even more preferably 1.8 to 3.0 g / 10 min. When the MFR of the polyethylene resin is equal to or greater than the lower limit, the effect of suppressing thickness variation during the formation of the easy-peel layer is enhanced. When the MFR of the polyethylene resin is equal to or less than the upper limit, the effect of suppressing adhesion of foreign matter originating from the resin film to the hot plate used for molding during heat molding of the resin film is enhanced.

[0045] In this specification, unless otherwise specified, "MFR" refers to a value measured in accordance with JIS K 6922-1.

[0046] Examples of the propylene-based copolymer contained in the easy-peel layer include propylene-ethylene random copolymer (also known as polypropylene random copolymer, rPP), propylene-ethylene block copolymer (also known as polypropylene block copolymer, bPP), and ethylene-propylene terpolymer (also known as ethylene propylene terpolymer, EPT).

[0047] The melting point of the polypropylene resin contained in the easy-peel layer is preferably 130 to 180° C., more preferably 140 to 170° C., and even more preferably 150 to 165° C. When the melting point of the polypropylene resin is in this range, the same effects as when the melting point of the polyethylene resin is in the above-mentioned range can be obtained.

[0048] The melt flow rate (MFR) of the polypropylene resin contained in the easy-peel layer is preferably 1.0 to 10 g / 10 min, more preferably 1.5 to 9.0 g / 10 min, and even more preferably 2.0 to 8.5 g / 10 min. When the MFR of the polypropylene resin is in this range, the same effects as when the MFR of the polyethylene resin is in the above range can be obtained.

[0049] The other components contained in the easy-peel layer can be selected arbitrarily depending on the purpose, and are not particularly limited. Examples of the other components contained in the easy-peel layer include additives known in the art. Examples of the additives include antifogging agents, antiblocking agents, antioxidants, antistatic agents, crystal nucleating agents, inorganic particles, viscosity reducers, thickeners, heat stabilizers, lubricants, infrared absorbers, and ultraviolet absorbers.

[0050] The polyethylene resin, the polypropylene resin, and the other components contained in the easy-peel layer may each be of only one type or of two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0051] In the easy-peel layer, the ratio of the total content of the polyethylene resin and the polypropylene resin to the total mass of the easy-peel layer (([content of polyethylene resin in easy-peel layer (parts by mass)] + [content of polypropylene resin in easy-peel layer (parts by mass)]) / [total mass of easy-peel layer (parts by mass)] × 100) is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, and even more preferably 95 to 100 mass%, and may be, for example, 97 to 100 mass%. When this ratio is equal to or greater than the lower limit, the properties of the easy-peel layer are improved. The ratio is usually the same as the ratio of the total content of the polyethylene-based resin and the polypropylene-based resin to the total content (parts by mass) of components that do not vaporize at room temperature in the resin composition for forming an easy peel layer, as described below (([content (parts by mass) of polyethylene-based resin in resin composition for forming an easy peel layer)] + [content (parts by mass) of polypropylene-based resin in resin composition for forming an easy peel layer)]) / [total content (parts by mass) of components that do not vaporize at room temperature in the resin composition for forming an easy peel layer] × 100). The relationship between the content of the components contained in any layer constituting the resin film and the content of the components contained in the resin composition for forming that layer is also the same for layers other than the easy-peel layer described below.

[0052] In this specification, "room temperature" means a temperature that is neither particularly cold nor hot, that is, an ordinary temperature, and examples thereof include temperatures of 15 to 25°C.

[0053] The easy-peel layer may consist of one layer (single layer) or two or more layers. When the easy-peel layer consists of multiple layers, these multiple layers may be the same or different from each other, and the combination of these multiple layers is not particularly limited as long as it does not impair the effects of the present invention. The easy-peel layer preferably consists of one layer (single layer).

[0054] In this specification, not only in the case of easy-peel layers, "multiple layers may be the same or different from one another" means "all layers may be the same, all layers may be different, or only some layers may be the same," and further, "multiple layers are different from one another" means "at least one of the constituent materials and thicknesses of each layer is different from one another."

[0055] The ratio of the thickness of the easy-peel layer to the thickness of the resin film is preferably 3 to 15%, more preferably 5 to 12%, and even more preferably 5 to 10%. When the ratio is equal to or greater than the lower limit, the seal strength of the easy-peel layer is increased within an appropriate range. When the ratio is equal to or less than the upper limit, the peeling feel of the packaging material is improved, and an excessive thickness of the easy-peel layer is avoided. When the easy-peel layer is made up of multiple layers, the ratio of the total thickness of these multiple layers to the thickness of the resin film is preferably within the above-mentioned range, which is not limited to the easy-peel layer but also applies to layers other than the easy-peel layer described below.

[0056] In this specification, for any layer constituting the resin film, including the easy-peel layer described above, the ratio of the thickness of that layer to the thickness of the resin film is described, but the total value of the ratios described for each layer shall not exceed 100%.

[0057] For the same reasons as in the case of the thickness ratio above, the thickness of the easy-peel layer is preferably 2 to 30 μm, more preferably 4 to 24 μm, and even more preferably 4 to 20 μm. When the easy-peel layer is made up of multiple layers, the total thickness of these multiple layers is preferably within the above-mentioned range. This applies not only to the easy-peel layer but also to layers other than the easy-peel layer described below.

[0058] <Flexible layer> The flexible layer is preferably a resin layer containing a resin, except that, unlike the easy-peel layer, the flexible layer does not contain a combination of the polyethylene resin and the polypropylene resin as the resin, or contains a combination of the polyethylene resin and the polypropylene resin, and the mass ratio of the polyethylene resin content (parts by mass):the polypropylene resin content (parts by mass) is outside the range of 60:40 to 30:70.

[0059] It is preferable that the resin is a polyolefin-based resin, i.e., the flexible layer contains a polyolefin-based resin. When the flexible layer contains a polyolefin-based resin, the flexibility of the resin film is further improved, and by using such a resin film, the seal strength of the package is more stabilized.

[0060] The flexible layer containing the polyolefin-based resin may or may not contain other components that do not fall under the category of polyolefin-based resins, as long as the effects of the present invention are not impaired.

[0061] In this specification, unless otherwise specified, the term "polyolefin resin" refers to a polymer (resin component) having structural units derived from an olefin. The polyolefin resin contained in the flexible layer may be a homopolymer of one type of olefin, or a copolymer of two or more types of olefins.

[0062] Examples of the polyolefin resin contained in the flexible layer include polyethylene resin and polypropylene resin. The polyethylene resin and polypropylene resin contained in the flexible layer may be the same as the polyethylene resin and polypropylene resin contained in the easy-peel layer.

[0063] Examples of the other components contained in the flexible layer include the same components as those contained in the easy-peel layer.

[0064] The polyolefin resin and the other components contained in the flexible layer may each be of only one type or of two or more types, and if there are two or more types, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0065] The polyolefin resin contained in the flexible layer is preferably a polyethylene resin, more preferably polyethylene, and even more preferably one or more selected from the group consisting of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and metallocene-catalyzed linear low-density polyethylene. By including a polyethylene resin in the flexible layer, the flexibility of the resin film is further improved.

[0066] In the flexible layer containing a polyolefin resin, the proportion of the polyolefin resin content (parts by mass) relative to the total mass (parts by mass) of the flexible layer is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, and even more preferably 95 to 100 mass%, and may be, for example, 97 to 100 mass%. When the proportion is equal to or greater than the lower limit, the effect obtained by the flexible layer containing a polyolefin resin in the resin film is further enhanced.

[0067] In the flexible layer containing polyethylene, the ratio of the polyethylene content (parts by mass) to the polyolefin resin content (parts by mass) is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and even more preferably 90 to 100% by mass, and may be, for example, 95 to 100% by mass. When the ratio is equal to or greater than the lower limit, the effect obtained by the flexible layer containing polyethylene in the resin film is further enhanced. When the polyethylene is one or more types selected from the group consisting of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and metallocene-catalyzed linear low-density polyethylene, it is particularly preferable that the ratio be in this range.

[0068] The flexible layer may consist of one layer (single layer) or two or more layers. When the flexible layer consists of multiple layers, these multiple layers may be the same or different from each other, and the combination of these multiple layers is not particularly limited as long as it does not impair the effects of the present invention. The flexible layer preferably consists of one layer (single layer).

[0069] The ratio of the thickness of the flexible layer to the thickness of the resin film is preferably 10 to 40%, more preferably 20 to 35%. When the ratio is equal to or greater than the lower limit, the flexibility of the resin film is further improved, and by using such a resin film, the seal strength of the package is more stable. When the ratio is equal to or less than the upper limit, excessive thickness of the flexible layer is avoided.

[0070] For the same reasons as in the case of the thickness ratio above, the thickness of the flexible layer is preferably 8 to 80 μm, and more preferably 16 to 70 μm.

[0071] <Oxygen barrier layer> The oxygen barrier layer is preferably a resin layer containing a resin that exhibits oxygen barrier properties (sometimes referred to herein as an "oxygen barrier resin").

[0072] The oxygen barrier layer containing the oxygen barrier resin may or may not contain other components that do not fall under the category of oxygen barrier resins, as long as the effects of the present invention are not impaired.

[0073] Examples of the oxygen barrier resin include ethylene-vinyl alcohol copolymer (EVOH, also known as saponified ethylene-vinyl acetate copolymer).

[0074] In the ethylene-vinyl alcohol copolymer, the ratio of the amount of structural units derived from ethylene to the total amount of structural units in the ethylene-vinyl alcohol copolymer (sometimes referred to herein as the "copolymerization ratio of ethylene") is preferably 25 to 45 mol%, more preferably 30 to 35 mol%. By having the ratio in this range, an oxygen barrier layer with high oxygen barrier properties can be more easily formed.

[0075] Examples of the other components contained in the oxygen barrier layer include the same components as those contained in the easy-peel layer.

[0076] The oxygen barrier layer may contain only one type of oxygen barrier resin and two or more types of other components, and when two or more types are contained, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0077] In the oxygen barrier layer containing an ethylene-vinyl alcohol copolymer, the proportion of the ethylene-vinyl alcohol copolymer content (parts by mass) relative to the total mass (parts by mass) of the oxygen barrier layer is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, and even more preferably 95 to 100 mass%, and may be, for example, 97 to 100 mass%. When the proportion is equal to or greater than the lower limit, the oxygen barrier property of the resin film is further improved.

[0078] The oxygen barrier layer may consist of one layer (single layer) or two or more layers. When the oxygen barrier layer consists of multiple layers, these multiple layers may be the same or different from each other, and the combination of these multiple layers is not particularly limited as long as it does not impair the effects of the present invention. The oxygen barrier layer preferably consists of one layer (single layer).

[0079] The ratio of the thickness of the oxygen barrier layer to the thickness of the resin film is preferably 3 to 15%, more preferably 5 to 12%. When this ratio is equal to or greater than the lower limit, the oxygen barrier properties of the resin film are improved. When this ratio is equal to or less than the upper limit, the oxygen barrier layer is prevented from becoming excessively thick.

[0080] For the same reasons as in the case of the thickness ratio above, the thickness of the oxygen barrier layer is preferably 2 to 30 μm, and more preferably 4 to 24 μm.

[0081] <Pinhole-resistant layer> The pinhole-resistant layer is preferably a resin layer containing a resin. Examples of the resin contained in the pinhole-resistant layer include polyamide.

[0082] The pinhole-resistant layer containing the polyamide may or may not contain other components that do not fall under the category of polyamide, as long as the effects of the present invention are not impaired.

[0083] Examples of the polyamide include polyamides obtained by polymerizing or copolymerizing nylon salts obtained by reacting cyclic lactams (lactams having 3 or more ring members), amino acids, or diamines with dicarboxylic acids.

[0084] Examples of the cyclic lactam include ε-caprolactam, ω-enantholactam, ω-laurolactam, α-pyrrolidone, and α-piperidone.

[0085] Examples of the amino acid include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

[0086] Examples of the diamine that forms the nylon salt include aliphatic amines such as tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, and 2,4,4-trimethylhexamethylenediamine; Alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, isophoronediamine, piperazine, bis(4-aminocyclohexyl)methane, and 2,2-bis-(4-aminocyclohexyl)propane; Examples include aromatic diamines such as metaxylylenediamine and paraxylylenediamine.

[0087] Examples of the dicarboxylic acid that forms the nylon salt include aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sepatic acid, undecanedioic acid, and dodecanedioic acid; Alicyclic carboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid; Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid.

[0088] More specifically, the polyamide may be, for example, 4-nylon, 6-nylon, 7-nylon, 11-nylon, 12-nylon, 46-nylon, 66-nylon, 69-nylon, 610-nylon, 611-nylon, 612-nylon, 6T-nylon, 6I nylon, a copolymer of 6-nylon and 66-nylon (nylon 6 / 66), a copolymer of 6-nylon and 610-nylon, a copolymer of 6-nylon and 611-nylon, a copolymer of 6-nylon and 12-nylon (nylon 6 / 12), or a copolymer of 6-nylon and 612 nylon. , copolymers of 6-nylon and 6T-nylon, copolymers of 6-nylon and 6I-nylon, copolymers of 6-nylon, 66-nylon and 610-nylon, copolymers of 6-nylon, 66-nylon and 12-nylon (nylon 6 / 66 / 12), copolymers of 6-nylon, 66-nylon and 612-nylon, copolymers of 66-nylon and 6T-nylon, copolymers of 66-nylon and 6I-nylon, copolymers of 6T-nylon and 6I-nylon, copolymers of 66-nylon, 6T-nylon and 6I-nylon, and copolymers of 66-nylon, 6T-nylon and 6I-nylon.

[0089] In terms of heat resistance, mechanical strength, availability, and the like, the polyamide is preferably 6-nylon (sometimes abbreviated as "Ny6" in this specification), 12-nylon, 66-nylon, nylon 6 / 66, nylon 6 / 12, or nylon 6 / 66 / 12.

[0090] Examples of the other components contained in the pinhole-resistant layer include the same components as those contained in the easy-peel layer.

[0091] The polyamide and other components contained in the pinhole-resistant layer may each be of only one type or of two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0092] In the pinhole-resistant layer containing polyamide, the proportion of the polyamide content (parts by mass) relative to the total mass (parts by mass) of the pinhole-resistant layer is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, and even more preferably 95 to 100 mass%, and may be, for example, 97 to 100 mass%. When the proportion is equal to or greater than the lower limit, the pinhole resistance of the resin film becomes higher.

[0093] The pinhole-resistant layer may consist of one layer (single layer) or two or more layers. When the pinhole-resistant layer consists of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as it does not impair the effects of the present invention. The pinhole-resistant layer preferably consists of one layer (single layer).

[0094] The ratio of the thickness of the pinhole-resistant layer to the thickness of the resin film is preferably 10 to 30%, more preferably 15 to 25%. When this ratio is equal to or greater than the lower limit, the pinhole resistance of the resin film is improved. When this ratio is equal to or less than the upper limit, the pinhole-resistant layer does not become excessively thick.

[0095] For the same reasons as in the case of the thickness ratio above, the thickness of the pinhole-resistant layer is preferably 8 to 60 μm, and more preferably 12 to 50 μm.

[0096] <Outer layer> The outer layer is preferably a resin layer containing a resin. Examples of the resin contained in the outer layer include polyolefin-based resins, etc. When the outer layer contains a polyolefin-based resin, the outer layer is more effective in protecting layers other than the outer layer in the resin film, and is also more effective in suppressing curling.

[0097] The outer layer containing the polyolefin-based resin may or may not contain other components that do not fall under the category of polyolefin-based resins, as long as the effects of the present invention are not impaired.

[0098] Examples of the polyolefin resin contained in the outer layer include polyethylene resin and polypropylene resin. The polyethylene resin and polypropylene resin contained in the outer layer may be the same as the polyethylene resin and polypropylene resin contained in the easy-peel layer.

[0099] Examples of the other components contained in the outer layer include the same components as those contained in the easy-peel layer.

[0100] The polyolefin resin and the other components contained in the outer layer may each be of only one type or of two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0101] The polyolefin resin contained in the outer layer is preferably a polypropylene resin, and more preferably one or more selected from the group consisting of homopolypropylene (hPP), propylene-ethylene random copolymer (rPP), propylene-ethylene block copolymer (bPP), and ethylene-propylene terpolymer (EPT).

[0102] In the outer layer containing a polyolefin resin, the proportion of the polyolefin resin content (parts by mass) relative to the total mass (parts by mass) of the outer layer is preferably 80 to 100 mass%, more preferably 90 to 100 mass%, and even more preferably 95 to 100 mass%, and may be, for example, 97 to 100 mass%. When the proportion is equal to or greater than the lower limit, the effect obtained by the outer layer containing a polyolefin resin in the resin film is further enhanced.

[0103] The outer layer may consist of one layer (single layer) or two or more layers. When the outer layer consists of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as it does not impair the effects of the present invention. The outer layer preferably consists of one layer (single layer).

[0104] The ratio of the thickness of the outer layer to the thickness of the resin film is preferably 10 to 40%, more preferably 20 to 35%. When the ratio is equal to or greater than the lower limit, the effect of the outer layer in protecting the layers other than the outer layer in the resin film is enhanced. When the ratio is equal to or less than the upper limit, the thickness of the outer layer can be prevented from becoming excessive.

[0105] For the same reasons as in the case of the thickness ratio above, the thickness of the outer layer is preferably 8 to 80 μm, and more preferably 16 to 70 μm.

[0106] <Adhesive layer> The adhesive layer bonds any two layers in the resin film together, and is not the outermost layer of the resin film. In Figure 1, adhesive layers are provided in two locations: between the flexible layer and the oxygen barrier layer, and between the pinhole-resistant layer and the outer layer. However, the locations and number of adhesive layers in the resin film are not limited to these and can be selected arbitrarily depending on the purpose. When adhesive layers are provided at two or more locations in the resin film, these two or more adhesive layers may be the same as or different from each other.

[0107] The adhesive layer is a layer containing a component that exhibits adhesiveness, and is preferably a resin layer that contains an adhesive resin as the component that exhibits adhesiveness.

[0108] The adhesive resin may be, for example, a modified polyolefin. The modified polyolefin is a resin having structural units derived from an olefin and having a polar group.

[0109] The adhesive layer containing the adhesive resin may or may not contain other components that do not fall under the category of adhesive resins, as long as the effects of the present invention are not impaired.

[0110] The modified polyolefin contained in the adhesive layer may be, for example, an acid-modified polyolefin having an acidic group as the polar group. Preferred examples of the acid-modified polyolefin include acid-modified polyethylene and acid-modified polypropylene.

[0111] Examples of the other components contained in the adhesive layer include the same components as those contained in the easy-peel layer.

[0112] The adhesive resin and the other components contained in the adhesive layer may each be of only one type or of two or more types, and if there are two or more types, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0113] In an adhesive layer containing an adhesive resin, the proportion of the content (parts by mass) of the adhesive resin relative to the total mass (parts by mass) of the adhesive layer may be, for example, 50 to 100% by mass.

[0114] The adhesive layer may consist of one layer (single layer) or two or more layers. When the adhesive layer consists of multiple layers, these multiple layers may be the same or different from each other, and the combination of these multiple layers is not particularly limited as long as it does not impair the effects of the present invention. The adhesive layer preferably consists of one layer (single layer).

[0115] The ratio of the thickness of the adhesive layer to the thickness of the resin film is preferably 3 to 15%, more preferably 3 to 10%. When the ratio is equal to or greater than the lower limit, the adhesive strength between the two layers due to the adhesive layer is increased. When the ratio is equal to or less than the upper limit, excessive thickness of the adhesive layer is avoided.

[0116] For the same reasons as in the case of the thickness ratio above, the thickness of the adhesive layer is preferably 2 to 30 μm, and more preferably 2 to 20 μm.

[0117] <Other layers> The resin film may or may not include the other layer. The type of the other layer is not particularly limited and can be selected arbitrarily depending on the purpose. The thickness of the other layer is not particularly limited, and can be selected arbitrarily depending on the type of the other layer. When the resin film has the other layers, the positions and number of the other layers on the resin film are not particularly limited and can be selected arbitrarily depending on the type or purpose of the other layers.

[0118] <Resin film thickness> The thickness of the resin film (total thickness) is not particularly limited, but is preferably 80 to 250 μm, and may be, for example, any of 80 to 150 μm, 130 to 200 μm, and 180 to 250 μm. When the thickness of the resin film is equal to or greater than the lower limit, the strength of the resin film becomes higher. When the thickness of the resin film is equal to or less than the upper limit, the resin film can be made thinner.

[0119] <Examples of preferred resin films> An example of a preferable resin film of the present embodiment is a resin film having an easy-peel layer as one outermost layer, the resin film further includes a flexible layer adjacent to the easy-peel layer, an outer layer as the other outermost layer, and an oxygen barrier layer and a pinhole resistant layer between the flexible layer and the outer layer; the easy-peel layer contains a polyethylene-based resin and a polypropylene-based resin, In the easy-peel layer, the mass ratio of [content of polyethylene-based resin (parts by mass)]:[content of polypropylene-based resin (parts by mass)] is 60:40 to 30:70, The easy-peel layer in the resin film and the polyethylene film were heat-sealed with their MDs aligned under conditions of a sealing temperature of 140°C, a sealing pressure of 0.15 MPa, and a sealing time of 2 seconds, and then a 15 mm wide region was cut from the heat-sealed region to prepare a first test piece whose length direction aligned with the MD. The polyethylene film was peeled from the resin film in the same direction as the MD of the first test piece at a peel rate of 200 mm / min in accordance with JIS Z 0238:1998 to measure the peel strength X(MD). A 15 mm wide region was cut from the heat-sealed region to prepare a second test piece whose length direction aligned with a direction perpendicular to the MD. The polyethylene film was peeled from the resin film in the same direction as the TD of the second test piece at a peel rate of 200 mm / min in accordance with JIS Z 0238:1998 to measure the peel strength X(TD). The peel strength X (MD) is 0.5 to 5 N / 15 mm, The peel strength X(TD) is 1 to 5 N / 15 mm, The value of [peel strength X (TD)] / [peel strength X (MD)] is 0.9 to 2.5, the flexible layer and the outer layer contain a polyolefin-based resin; the oxygen barrier layer comprises an ethylene-vinyl alcohol copolymer; The pinhole-resistant layer may be a resin film containing polyamide.

[0120] Another example of a preferable resin film of the present embodiment is a resin film having an easy-peel layer as an outermost layer, the easy-peel layer contains a polyethylene-based resin and a polypropylene-based resin, In the easy-peel layer, the mass ratio of [content of polyethylene-based resin (parts by mass)]:[content of polypropylene-based resin (parts by mass)] is 43:57 to 30:70, The easy-peel layer in the resin film and the polyethylene film were heat-sealed with their MDs aligned under conditions of a sealing temperature of 140°C, a sealing pressure of 0.15 MPa, and a sealing time of 2 seconds, and then a 15 mm wide region was cut from the heat-sealed region to prepare a first test piece whose length direction aligned with the MD. The polyethylene film was peeled from the resin film in the same direction as the MD of the first test piece at a peel rate of 200 mm / min in accordance with JIS Z 0238:1998 to measure the peel strength X(MD). A 15 mm wide region was cut from the heat-sealed region to prepare a second test piece whose length direction aligned with a direction perpendicular to the MD. The polyethylene film was peeled from the resin film in the same direction as the TD of the second test piece at a peel rate of 200 mm / min in accordance with JIS Z 0238:1998 to measure the peel strength X(TD). The peel strength X (MD) is 0.5 to 5 N / 15 mm, The peel strength X(TD) is 1 to 5 N / 15 mm, The value of [peel strength X (TD)] / [peel strength X (MD)] is 0.9 to 2.5, The ratio of the thickness of the easy-peel layer to the thickness of the resin film is 5 to 10%.

[0121] <<Resin film manufacturing method>> The resin film can be produced, for example, by a feed block method in which resins or resin compositions that are materials for forming each layer are melt-extruded using several extruders, a coextrusion T-die method such as a multi-manifold method, or an air-cooled or water-cooled coextrusion inflation method.

[0122] When the resin composition is used, for example, a mixture of two or more components (dry blend, non-kneaded mixture) may be directly fed into the extruder as the resin composition, or a pre-kneaded mixture of two or more components may be fed into the extruder as the resin composition. The pre-kneaded mixture can be obtained, for example, by melt-kneading two or more components using a device such as a twin-screw extruder or a Banbury mixer.

[0123] The resin film can also be produced by separately preparing two or more films to constitute any two or more of the layers in advance, laminating them together using a thermal lamination method or the like without using an adhesive, and further laminating other layers as needed to achieve the desired arrangement.

[0124] The resin composition used as a material for forming any layer in the resin film may be produced by adjusting the types and contents of the components contained therein so that the layer to be formed contains the desired components in the desired amounts. For example, the ratio of the contents of the components that do not vaporize at room temperature in the resin composition is usually the same as the ratio of the contents of the components in the layer formed from this resin composition.

[0125] The resin composition for forming the easy peel layer may be, for example, a resin composition containing a polyethylene resin, a polypropylene resin, and, if necessary, the other components described above. The resin composition for forming the flexible layer may be, for example, a resin composition containing a polyolefin resin and, if necessary, the other components described above. Examples of the resin composition for forming the oxygen barrier layer include a resin composition containing an oxygen barrier resin and, if necessary, the other components described above. The resin composition for forming the pinhole resistant layer may be, for example, a resin composition containing polyamide and, if necessary, the other components described above. The resin composition for forming the outer layer may be, for example, a resin composition containing a polyolefin resin and, if necessary, the other components described above. The resin composition for forming the adhesive layer may be, for example, a resin composition containing an adhesive resin and, if necessary, the other components described above. The components contained in these resin compositions are the components explained above.

[0126] <<Packaging>> A packaging body according to one embodiment of the present invention is constructed using the resin film according to one embodiment of the present invention described above. The packaging body of this embodiment is made of the resin film, and is therefore easy to peel, providing a good peeling feel when opened.

[0127] More specifically, an easy-peel type package can be produced by heat-sealing one packaging material having an easy-peel layer using the resin film with the other packaging material, and when the package is opened, the packaging material having the easy-peel layer can be peeled off with ease. The one packaging material may be, for example, the resin film itself or a molded product of the resin film. The other packaging material is not particularly limited as long as it can be heat-sealed.

[0128] The packaging body of this embodiment has the above-mentioned properties and is therefore suitable for use in packaging food, for example. That is, preferred packaging bodies include those that package food.

[0129] Examples of the food include processed fresh fish foods such as kamaboko (fish paste), seafood such as shellfish, and processed meat foods such as ham and sausage. Examples of the kamaboko include imitation crab sticks (kamaboko with a flavor, texture, and appearance similar to crab meat). Examples of the shellfish include scallops.

[0130] The packaging body of this embodiment may be a known packaging body except that the resin film is used.

[0131] A preferred packaging body of this embodiment is, for example, a packaging body that has a lid material and a base material and is formed by sealing the lid material and the base material, wherein the base material is one of the packaging materials and the lid material is the other packaging material. The base material may be, for example, a molded product of the resin film having a recess for forming a storage section in a package.

[0132] The base material may be a deep-drawn molded article of the resin film. That is, the packaging body of the present embodiment, which includes a lid material and a base material, may be a deep-drawn packaging body.

[0133] FIG. 2 is a cross-sectional view schematically showing an example of the packaging body of this embodiment. In FIG. 2, the same components as those shown in FIG. 1 are denoted by the same reference numerals as in FIG. 1, and detailed description thereof will be omitted.

[0134] The packaging body 101 shown in Fig. 2 is configured to include a lid material 8 and a base material 10. The base material 10 is configured using the resin film 1 shown in Fig. 1, and in this case is a molded body (heat-molded body) of the resin film 1. In the base material 10 in FIG. 2, the distinction between the layers in the resin film 1 that constitutes it is omitted.

[0135] The base material 10 has a recess 100 formed therein. One side 10b of the base material 10 (sometimes referred to as the "second side" in this specification) and one side 8b of the lid material 8 (sometimes referred to as the "second side" in this specification) are both sealing surfaces, and these face each other in the packaging body 101. In the package 101, the second surface 10b of the base material 10, excluding the area where the recess 100 is formed, is overlapped with an area of ​​the second surface 8b of the lid material 8, near the peripheral edge. Of the overlapping areas of the base material 10 and the lid material 8, at least the areas near their peripheral edges are sealed to form the package 101. As a result, in the area of ​​the recess 100 of the base material 10, a storage section 101a is formed between the second surface 10b of the base material 10 and the second surface 8b of the lid material 8. An item 9 is stored in this storage section 101a.

[0136] The thickness of the base material 10 at its flat portion may be the same as the thickness of the resin film described above. The thickness of the lid material 8 is preferably 50 to 150 μm.

[0137] The second surface 10b of the base material 10 is the same as the surface 11b of the easy-peel layer 11 in the resin film 1, opposite the flexible layer 12 side. The other surface 10a of the base material 10 is the same as the surface 15a of the outer layer 15 in the resin film 1, opposite the easy-peel layer 11 side.

[0138] The lid material 8 is preferably a resin film containing a resin, and more preferably a resin film other than the resin film according to one embodiment of the present invention. A preferred example of the lid material 8 is a resin film in which at least the second surface 8b contains polyethylene or polypropylene, and may be a single-layer resin film, or a polyethylene film or polypropylene film. Since one of the packaging materials, such as the base material 10, has the easy-peel layer, the packaging body of this embodiment exhibits good easy-peel properties and a good peeling feel, regardless of whether the sealing surface of the other packaging material, such as the lid material 8, is composed of polyethylene or polypropylene.

[0139] The packaging body of this embodiment is not limited to the packaging body 101 shown in Figure 2, and for example, some of the configuration of the packaging body 101 may be changed, deleted, or added within the scope of the spirit of the present invention. For example, in the packaging body 101, the base material 10 is made of the resin film 1 shown in FIG. 1, but may be made of a resin film other than the resin film 1 of this embodiment. For example, the packaging body 101 is constructed using a base material 10 which is a molded body of resin film 1, but the packaging body of this embodiment may also be constructed using an unmolded resin film 1 instead of a molded body of resin film 1.

[0140] <<Packaging manufacturing method>> The packaging body can be produced by packaging an object to be packaged (in other words, an object to be stored) with the resin film. The packaging body can be produced in the same manner as conventional packaging bodies, except that the resin film is used instead of the conventional resin film. When producing a package, the easy-peel layer in the resin film or its molded product is placed toward the object to be packaged, and the object is packaged.

[0141] In the case of deep-drawn packaging, for example, a storage section for storing the packaged item (in other words, the contents) is formed using a deep-drawn molded body of the resin film (i.e., the base material) and another resin film (i.e., the lid material), and the packaged item is stored while the molded body and the other resin film are heated and sealed in areas other than the storage section, thereby producing a deep-drawn packaging.

[0142] Regardless of the form of the package, when producing the package, the sealing temperature during heat sealing between the one packaging material and the other packaging material is preferably 120 to 160°C, and the sealing pressure is preferably 0.1 to 0.3 MPa.

[0143] The resin film may be thermoformed into one of the packaging materials by a known method, for example, preferably at a temperature of 70 to 120°C. [Example]

[0144] The present invention will be described in more detail below with reference to specific examples, although the present invention is not limited to the examples shown below.

[0145] The resins used in each example or comparative example are as follows. hPP: Homopolypropylene (Sumitomo Chemical Co., Ltd., "Noblen (registered trademark) FS2011DG2", melting point 158°C, MFR 2.5 g / 10 min, density 0.9 g / cm 3 ) LDPE: Low-density polyethylene (Ube Polyethylene "L211", density 0.924 g / cm 3 , MFR 2g / 10min, melting point 112℃) EPT: Ethylene propylene terpolymer (Sumitomo Chemical Co., Ltd., "Noblen® FL8115A"; melting point: 148°C, MFR: 8g / 10min, density: 0.9g / cm 3 ) Ny: 6-Nylon (DSC "B40L09") EVOH: Ethylene-vinyl alcohol copolymer (Kuraray "J171B", ethylene copolymerization ratio 32%) LLDPE: Linear low-density polyethylene (Dow "2607G", density 0.918 g / cm 3 , MFR2.3g / 10min) Modified PE: Maleic anhydride modified polyethylene (adhesive resin, "Admer (registered trademark) NF536" manufactured by Mitsui Chemicals, Inc.) Modified PP: Acid-modified polypropylene (adhesive resin, "Admer (registered trademark) QP565" manufactured by Mitsui Chemicals, Inc.)

[0146] [Example 1] <Production of Resin Composition> The LDPE (60 parts by mass) and the hPP (40 parts by mass) were mixed at room temperature to produce a resin composition (1).

[0147] <<Resin film manufacturing>> A resin film having the structure shown in FIG. 1 was produced according to the following procedure. That is, by co-extruding the resin composition (1), the LLDPE, the modified PE, the EVOH, the Ny, the modified PP, and the EPT in this order, a resin film (thickness 150 μm) was obtained, which was composed of an easy-peel layer (thickness 10.5 μm), a flexible layer (thickness 45 μm), a first adhesive layer (thickness 7.5 μm), an oxygen barrier layer (thickness 9 μm), a pinhole-resistant layer (thickness 30 μm), a second adhesive layer (thickness 7.5 μm), and an outer layer (thickness 40.5 μm) laminated in this order in the thickness direction.

[0148] <<Evaluation of resin film>> <Measurement of peel strength X (MD) and peel strength X (TD), and calculation of [peel strength X (TD)] / [peel strength X (MD)]> The easy-peel layer in the resin film obtained above and a polyethylene film (Sumitomo Bakelite Co., Ltd., "SUMILITE (registered trademark) CEL-9200A", thickness 60 μm) were heat-sealed with the MD of these films aligned under the conditions of a sealing temperature of 140°C, a sealing pressure of 0.15 MPa, and a sealing time of 2 seconds. This heat-sealing was performed using a semi-automatic packaging machine (Multivac Japan, "R535").

[0149] Next, a 15 mm wide region was cut from the heat-sealed portion of the obtained heat-sealed body to prepare a first test piece. The MD (MD of the resin film and the polyethylene film) and the length direction of this first test piece were aligned. At room temperature, the polyethylene film was peeled from the resin film in the same direction as the MD (the length direction of the first test piece) at a peel rate of 200 mm / min in accordance with JIS Z 0238:1998 to measure the peel strength X(MD). This measurement of peel strength X(MD) was performed on two of the first test pieces, and the average of the measured values ​​was used as the peel strength X(MD). The results are shown in Table 1.

[0150] Separately, a 15 mm wide region was cut from the heat-sealed portion of the obtained heat-sealed body to prepare a second test piece. The length direction of this second test piece was aligned with the TD (TD of the resin film and polyethylene film). Similarly, in accordance with JIS Z 0238:1998, the polyethylene film was peeled from the resin film in the same direction as the TD (length direction of the second test piece) at room temperature at a peel rate of 200 mm / min, and the peel strength X(TD) was measured. This measurement of peel strength X(TD) was performed on two of the second test pieces, and the average of the measured values ​​was used as the peel strength X(TD). The results are shown in Table 1.

[0151] Furthermore, the value of [peel strength X (TD)] / [peel strength X (MD)] was calculated from these average values. The results are shown in Table 1.

[0152] <<Production and evaluation of resin film>> [Example 2] The LDPE (50 parts by mass) and the hPP (50 parts by mass) were mixed at room temperature to produce a resin composition (2). Except for using this resin composition (2) instead of the resin composition (1), a resin film (thickness: 150 μm) was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0153] [Example 3] The LDPE (45 parts by mass) and the hPP (55 parts by mass) were mixed at room temperature to produce a resin composition (3). Except for using this resin composition (3) instead of the resin composition (1), a resin film (thickness: 150 μm) was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0154] [Example 4] The LDPE (40 parts by mass) and the hPP (60 parts by mass) were mixed at room temperature to produce a resin composition (4). Except for using this resin composition (4) instead of the resin composition (1), a resin film (thickness: 150 μm) was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0155] [Example 5] The LDPE (35 parts by mass) and the hPP (65 parts by mass) were mixed at room temperature to produce a resin composition (5). Except for using this resin composition (5) instead of the resin composition (1), a resin film (thickness: 150 μm) was produced and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0156] [Example 6] The LDPE (30 parts by mass) and the hPP (70 parts by mass) were mixed at room temperature to produce a resin composition (6). Except for using this resin composition (6) instead of the resin composition (1), a resin film (thickness: 150 μm) was produced and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0157] [Comparative Example 1] The LDPE (83 parts by mass) and the hPP (17 parts by mass) were mixed at room temperature to produce a resin composition (R1). Except for using this resin composition (R1) instead of the resin composition (1), a resin film (thickness: 150 μm) was produced and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0158] Comparative Example 2 The LDPE (70 parts by mass) and the hPP (30 parts by mass) were mixed at room temperature to produce a resin composition (R2). Except for using this resin composition (R2) instead of the resin composition (1), a resin film (thickness: 150 μm) was produced and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0159] [Table 1]

[0160] [Table 2]

[0161] As is clear from the above results, in Examples 1 to 6, the peel strength X (MD) was 0.7 to 1.75 N / 15 mm, and the peel strength X (TD) was 1.14 to 2.36 N / 15 mm. The value of [peel strength X (TD)] / [peel strength X (MD)] was 1.35 to 1.65, and the anisotropy of the peel strength in MD and TD was low. In particular, in Examples 4 to 6, the value of [peel strength X (TD)] / [peel strength X (MD)] was 1.35 to 1.52, which was closer to 1.

[0162] Wider test pieces were prepared, identical to the test pieces used to measure peel strength X (MD) and peel strength X (TD), except that they were wider than 15 mm (the area of ​​the heat-sealed region was wider). Using these wider test pieces, three monitors actually performed a sensory evaluation of the peeling sensation when the polyethylene film was peeled from the resin film in any peeling direction. More specifically, the entire area of ​​these test pieces, excluding the region assumed to be the storage section, was the heat-sealed region, and the ratio of the surface area of ​​the heat-sealed region to the surface area of ​​the test piece when viewed from above was set to 50% or more. As a result, in all of Examples 1 to 6, the polyethylene film could be peeled from the resin film smoothly and comfortably with an appropriate peel strength, and the peeling sensation was judged to be good. In particular, Examples 4 to 6 were judged to have excellent peeling sensation.

[0163] In the easy peel layers of Examples 1 to 6, the mass ratio of [polyethylene resin content (parts by mass)]:[polypropylene resin content (parts by mass)] was 60:40 to 30:70, and in Examples 4 to 6, the mass ratio was 40:60 to 30:70.

[0164] In Examples 1 to 6, the ratio of the thickness of the easy-peel layer to the thickness of the resin film was 7%.

[0165] In contrast, in Comparative Examples 1 and 2, although the peel strengths X(MD) and X(TD) were comparable to those in Examples 1 to 6, the value of [peel strength X(TD)] / [peel strength X(MD)] was 2.66 or more (2.66 to 2.75), and the anisotropy of the peel strength in MD and TD was high. In fact, as in Examples 1 to 6, a sensory evaluation was conducted on the peeling sensation when the polyethylene film was peeled from the resin film using a wide test piece, and it was determined that Comparative Examples 1 and 2 felt strange.

[0166] In the easy peel layers of Comparative Examples 1 and 2, the mass ratio of [polyethylene resin content (parts by mass)]:[polypropylene resin content (parts by mass)] was 83:17 to 70:30. [Industrial Applicability]

[0167] The present invention can be used to manufacture easy-peel type packaging products. [Explanation of symbols]

[0168] 1. Resin film 11. Easy-peel layer 12...Flexible layer 13. Oxygen barrier layer 14. Pinhole-resistant layer 15...outer layer 101...Packaging 8...Lid material 9. Storage items 10. Base material (molded resin film)

Claims

1. A resin film having an easy-peel layer as an outermost layer, the easy-peel layer contains a polyethylene-based resin and a polypropylene-based resin, In the easy-peel layer, the mass ratio of [content (parts by mass) of polyethylene-based resin]:[content (parts by mass) of polypropylene-based resin] is 60:40 to 30:70, The easy-peel layer in the resin film and the polyethylene film were heat-sealed with their MD aligned under conditions of a sealing temperature of 140°C, a sealing pressure of 0.15 MPa, and a sealing time of 2 seconds, and then a 15 mm wide region was cut from the heat-sealed region to prepare a first test piece whose length direction aligned with the MD. The polyethylene film was peeled from the resin film in the same direction as the MD at a peel rate of 200 mm / min in accordance with JIS Z 0238:1998 to measure the peel strength X(MD). A 15 mm wide region was cut from the heat-sealed region to prepare a second test piece whose length direction aligned with a direction perpendicular to the MD. The polyethylene film was peeled from the resin film in the same direction as the TD at a peel rate of 200 mm / min in accordance with JIS Z 0238:1998 to measure the peel strength X(TD). The peel strength X (MD) is 0.5 to 5 N / 15 mm, The peel strength X(TD) is 1 to 5 N / 15 mm, A resin film having a value of [peel strength X (TD)] / [peel strength X (MD)] of 0.9 to 2.

5.

2. The resin film according to claim 1 , further comprising a flexible layer adjacent to the easy-peel layer.

3. The resin film according to claim 2 , wherein the flexible layer comprises a polyolefin resin.

4. 3. The resin film according to claim 1, wherein the ratio of the thickness of the easy peel layer to the thickness of the resin film is 5 to 10%.

5. The resin film according to claim 1 or 2, further comprising a pinhole-resistant layer.

6. The resin film according to claim 1 or 2, further comprising an oxygen barrier layer.

7. The resin film according to claim 1 or 2, further comprising an outer layer.

8. A packaging body constructed using the resin film according to claim 1 or 2.

9. 10. The package of claim 8, wherein the package contains a food product.

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