Packaging material and method for preserving articles using the same

Abstract

To provide a packaging material that suppresses outgassing containing acidic and alkaline components, and a method for preserving articles using this packaging material.SOLUTION: A packaging material for packaging articles that comprises a resin (A) containing an alicyclic structure-containing polymer on the outermost part in the thickness direction of the packaging material, and a method for preserving articles using this packaging material are provided.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a packaging material and a method for preserving an article using the same. [Background technology]

[0002] For example, packaging materials are used to protect articles from vibrations, shocks, etc. during transportation, and from dust, etc. during storage. Examples of packaging materials include paper and resin film materials (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-315363 Summary of the Invention [Problem to be solved by the invention]

[0004] However, some articles, such as artworks, semiconductor products, electronic products, and aerospace equipment, may be deteriorated by trace amounts of acidic and alkaline components in the air, and therefore, these articles are usually required to be handled in an environment where the amounts of acidic and alkaline components in the air are strictly controlled.

[0005] However, packaging materials used for the above-mentioned items have not been thoroughly studied, and packaging materials used for general items are often used.

[0006] The inventors have investigated the components of gas (outgassing) released from conventional packaging materials made of paper and resin film, and have confirmed that the gas may contain acid components such as formic acid and acetic acid, or alkaline components such as sodium ions and calcium ions. This raises concerns that outgassing from conventional packaging materials may cause deterioration of some items, such as artworks.

[0007] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a packaging material that suppresses outgassing containing acid components and alkaline components, and a method for preserving articles using the same. [Means for solving the problem]

[0008] As a result of extensive research, the present inventors have found that a resin containing an alicyclic structure-containing polymer can suppress outgassing containing the above-mentioned acid components and alkali components, and have thus completed the present invention.

[0009] The present invention includes the following. <1> A packaging material for packaging an article, comprising a resin (A) containing an alicyclic structure-containing polymer at the outermost portion in the thickness direction of the packaging material. <2> The resin (A) contains a crystalline alicyclic structure-containing polymer. <1> The packaging material described in <3> The packaging material has a resin layer containing the resin (A). <1> or <2> The packaging material described in <4> the packaging material has a multilayer film having a first skin layer, a core layer, and a second skin layer, and the first skin layer and the second skin layer are resin layers containing the resin (A); <1> ~ <3> The packaging material according to any one of claims 1 to 4. <5> The core layer contains an ultraviolet absorber. <4> The packaging material described in <6> The packaging material is a bubble sheet having a cap film and a back film, and the cap film and the back film have a resin layer containing the resin (A). <3> The packaging material described in <7> The packaging material is a nonwoven fabric made of resin fibers, and the resin fibers contain the resin (A). <1> or <2> The packaging material described in <8> The packaging material is a packaging material for packaging artworks. <1> ~ <7> The packaging material according to any one of claims 1 to 4. <9> The weight ratio of the alicyclic structure-containing polymer contained in the resin (A) is 70% by weight or more. <1> ~ <8> The packaging material according to any one of claims 1 to 4. <10> the amount of at least one of acetic acid, formic acid, sodium ions, and calcium ions detected from the resin (A) is 1 μg / g or less; <1> ~ <9> The packaging material according to any one of claims 1 to 4. <11> A method for preserving an article, comprising packaging an article using a packaging material and preserving the resulting package, the packaging material comprising: <1> ~ <10> A method for storing an article, the article being the packaging material according to any one of claims 1 to 4. <12> The article is a work of art. <11> A method for storing an item described in [Effects of the Invention]

[0010] According to the present invention, a packaging material in which outgassing containing acid components and alkali components is suppressed by containing a resin (A) containing an alicyclic structure-containing polymer in the outermost part in the thickness direction of the packaging material, and a method for preserving an article using the same can be provided. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating an example of a packaging material according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing another example of a packaging material according to one embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view schematically showing another example of a packaging material according to one embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view schematically showing another example of a packaging material according to one embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view schematically showing another example of a packaging material according to one embodiment of the present invention. [Figure 6] FIG. 6 is a perspective view that schematically shows an example of resin fibers that constitute a packaging material according to one embodiment of the present invention. [Figure 7] FIG. 7 is a perspective view that schematically shows another example of resin fibers that constitute a packaging material according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be modified and implemented as desired without departing from the scope of the claims of the present invention and their equivalents. The components of the embodiments shown below can be combined as appropriate. In addition, in the drawings, the same components are designated by the same reference numerals, and their description may be omitted.

[0013] <1. Overview of packaging materials> A packaging material according to one embodiment of the present invention is a packaging material for packaging an article, and contains a resin (A) containing an alicyclic structure-containing polymer at the outermost portion in the thickness direction of the packaging material.

[0014] The packaging material is usually in the form of a sheet. Unless otherwise specified, the term "sheet" refers to a member having a shape in which the dimension in one direction (thickness) is smaller than the length and width dimensions when viewed in that direction (thickness direction).

[0015] The outermost part in the thickness direction of the packaging material refers to the part exposed on the outer surface (the surface in contact with the outside of the packaging material) in the thickness direction of the packaging material, and usually refers to the part from the outer surface to a predetermined thickness. The thickness of the outermost part is usually 2 μm.

[0016] According to this embodiment, since the outermost part in the thickness direction of the packaging material contains the resin (A) containing the alicyclic structure-containing polymer, the packaging material can be one in which outgassing containing acid components and alkali components is suppressed.

[0017] Although the mechanism by which the packaging material according to the present embodiment can suppress outgassing containing acid and alkaline components is unclear, the inventors speculate as follows: However, the technical scope of the present invention is not limited to the reasons described below.

[0018] Alicyclic structure-containing polymers are basically formed by a low-polarity hydrocarbon skeleton, and therefore have low polarity and have the property of being difficult to incorporate highly polar molecules such as water. Therefore, they are not easily absorbed by acid components such as formic acid and acetic acid, or by sodium ions (Na + ) and calcium ions (Ca 2+ The present inventors speculate that the alicyclic structure-containing polymer is unlikely to contain polar compounds such as water, which can cause the generation of alkaline components such as carboxylic acids and carboxylic acids, and that polar compounds are unlikely to penetrate from the outside, and therefore outgassing containing acid components and alkaline components is reduced in the packaging material.

[0019] Furthermore, since the alicyclic structure-containing polymer can be one that does not contain the element O as a constituent element of the polymer, it is presumed that formic acid (HCOOH) and acetic acid (CHCOOH) are unlikely to be produced during the resin synthesis process. Furthermore, the inventors presume that, since the alicyclic structure-containing polymer has a cyclic structure, even if radicals that cause resin degradation are produced for some reason, the cyclic structure will capture the radicals, suppressing resin degradation and making it unlikely that acid components such as formic acid and acetic acid will be produced as decomposition products due to degradation. Furthermore, the inventors presume that, since a resin that is resistant to degradation can be present at the outermost part of the packaging material, when the packaging material contains additives, it is possible to prevent the acid and alkaline components contained in the additives from being released to the outside.

[0020] The amount of outgassing, including acid and alkaline components, released from conventionally used paper packaging materials and packaging materials made of resin, such as polyethylene, has little or no effect on general items such as daily necessities and home appliances. Therefore, until now, sufficient research has not been conducted on outgassing from packaging materials, and conventional packaging materials have been used even for items that are highly affected by acid and alkaline components, such as works of art.

[0021] However, as mentioned above, there is a concern that outgassing from conventional packaging materials may cause deterioration of items that are highly susceptible to acidic and alkaline components, such as artworks. Furthermore, since packaging materials are generally used for long-term storage, there is also a concern that the items may deteriorate over time if conventional packaging materials are used. The present invention is based on a novel problem that has not been recognized until now.

[0022] <2. Packaging material type> The packaging material according to this embodiment is typically in the form of a sheet containing resin (A) at the outermost part in its thickness direction. The packaging material may, for example, be rigid enough to form a housing, or flexible enough to be used to wrap an article, with the latter being preferred. Flexible packaging materials are typically used in a state where the article and the packaging material are in direct contact with each other, and this is because they can suppress outgassing in packaging materials with specifications that tend to deteriorate the article. "Direct" contact between an article and a packaging material refers to a state where the article and the packaging material are in contact with each other without any other components between them.

[0023] Preferred examples of the packaging material include a form having a resin layer containing the resin (A), specifically a film having a resin layer containing the resin (A), and a processed product of the film. Also, preferred examples of the packaging material include a nonwoven fabric made of resin fibers containing the resin (A).

[0024] <2.1. When the packaging material is film> When the packaging material according to this embodiment is a film, it usually has a resin layer containing the resin (A) as the layer in contact with the outside of the packaging material.

[0025] FIG. 1 is a cross-sectional view schematically illustrating an example of a packaging material according to one embodiment of the present invention. The packaging material 10A shown in FIG. 1 includes a resin layer 1 containing a resin (A) that includes an alicyclic structure-containing polymer. As shown in FIG. 1, the packaging material 10A is composed of a monolayer film having a resin layer 1. In the packaging material 10A, the main surface 1U and the main surface 1D of the resin layer 1 each correspond to the surface that contacts the outside of the packaging material 10A, and the portion having a predetermined thickness t from the main surface 1U corresponds to the outermost portion M1, while the portion having a predetermined thickness t from the main surface 1D corresponds to the outermost portion M2. In the packaging material 10A, the entire resin layer 1 contains the resin (A), and therefore the outermost portions M1 and M2 of the packaging material 10A can contain the resin (A).

[0026] Fig. 2 is a cross-sectional view schematically illustrating another example of a packaging material according to one embodiment of the present invention. As shown in Fig. 2, packaging material 10B is composed of a multilayer film including first skin layer 11, core layer 12, and second skin layer 13, with first skin layer 11 and second skin layer 13 being resin layers 1 containing resin (A). In packaging material 10B, of main surfaces 11U and 11D of first skin layer 11, main surface 11U corresponds to the surface that contacts the outside of packaging material 10B, and of main surfaces 13U and 13D of the second skin layer, main surface 13D corresponds to the surface that contacts the outside of packaging material 10B. In addition, in packaging material 10B, a portion having a predetermined thickness t from main surface 11U corresponds to outermost portion M1, and a portion having a predetermined thickness t in the thickness direction from main surface 13D corresponds to outermost portion M2. In packaging material 10B, first skin layer 11 and second skin layer 13 are resin layers 1 containing resin (A), and therefore outermost layers M1 and M2 of packaging material 10B can contain resin (A).

[0027] 2, the main surface 11D of the first skin layer 11 is provided on the main surface 12U of the core layer 12, and the main surface 13U of the second skin layer 13 is provided on the main surface 12D of the core layer 12. In this packaging material 10B, the core layer 12 is provided between the first skin layer 11 and the second skin layer 13, which can prevent components contained in the core layer 12 from being released to the outside of the packaging material 10B. Therefore, the material of the core layer 12 can be a resin containing optional components such as an ultraviolet absorber or a colorant, for example.

[0028] The core layer 12 and the first skin layer 11 may be in direct contact with each other, or an optional layer (not shown) may be provided between them. The core layer 12 and the second skin layer 13 may be in direct contact with each other, or an optional layer (not shown) may be provided between them. Here, "a layer being in "direct" contact with another layer" means that there is no other layer between the two layers.

[0029] 2 shows an example in which the packaging material is a multilayer film having a three-layer structure, but the present invention is not limited thereto, and the packaging material in this embodiment may be a multilayer film having two or more core layers. The number of layers constituting the multilayer film may be appropriately selected depending on the application of the packaging material, but is typically 1 to 10 layers. Even when the packaging material is composed of multiple resin layers, the above-mentioned first skin layer and second skin layer are typically provided as the outermost layers of the multilayer film.

[0030] The total thickness of the resin film that can be used as a packaging material can be appropriately selected depending on the application of the packaging material, but is usually 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and is usually 600 μm or less, preferably 500 μm or less, more preferably 400 μm or less. When the total thickness of the resin film is in the above range, the flexibility of the packaging material can be improved, and the packaging material can have good conformability to the article.

[0031] When the resin film usable as a packaging material is a multilayer film, the thickness of the skin layer is usually 2 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more, and usually 90 μm or less, preferably 80 μm or less, and more preferably 50 μm or less. Having a skin layer thickness within this range can effectively suppress outgassing from the packaging material. Furthermore, when the core layer contains optional components, bleeding out of the optional components can be effectively suppressed.

[0032] When the resin film usable as a packaging material is a multilayer film, the thickness of the core layer can be appropriately selected depending on the application of the packaging material, but is usually 2 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more, and is usually 90 μm or less, preferably 80 μm or less, and more preferably 50 μm or less. This is because having the thickness of the skin layer in the above range makes it easier to adjust the content of additives in the core layer. When the core layer contains two or more core layers, the thickness of the core layer is the sum of the thicknesses of the individual core layers.

[0033] When the resin film usable as a packaging material is a multilayer film, there are no restrictions on the ratio of the skin layer thickness to the total thickness of the multilayer film, and the ratio of the core layer thickness to the total thickness of the multilayer film, and these can be appropriately selected depending on the application of the packaging material. The ratio of the thickness of each skin layer to the total thickness of the multilayer film is usually 0.02 or more, preferably 0.05 or more, more preferably 0.1 or more, and usually 0.6 or less, preferably 0.5 or less, more preferably 0.4 or less. Furthermore, the ratio of the core layer thickness to the total thickness of the multilayer film is usually 0.1 or more, preferably 0.15 or more, more preferably 0.2 or more, and usually 0.9 or less, preferably 0.8 or less, more preferably 0.7 or less.

[0034] The thickness of a film used as a packaging material can be measured using a microshape measuring device, a spectroscopic film thickness measuring device, etc. When the packaging material is a multilayer film, the thickness of each layer can be measured, for example, by cutting the film with a microtome and observing the cross section with an optical microscope.

[0035] <2.2. When the packaging material is a film-processed product> When the packaging material according to this embodiment is a film product, the film constituting the film product usually has a resin layer containing the resin (A).

[0036] A preferred example of a processed film is a bubble sheet, also known as a bubble cushioning material, which is a sheet that holds air bubbles by trapping gas (usually air) between two sheets of film and uses the bubbles as a cushioning material.

[0037] 3 and 4 are cross-sectional views schematically illustrating another example of a packaging material according to one embodiment of the present invention. As shown in FIG. 3, a packaging material 20A includes a cap film 21 having protrusions 21p for trapping air 2, and a back film 22. Specifically, a hollow space is formed between the cap film 21 and the back film 22, and air 2 is trapped in this hollow space. In this case, the cap film 21 and the back film 22 include a resin layer 1 containing a resin (A). When the cap film 21 and the back film 22 include the resin layer 1, the resin layer 1 is typically provided so that the outermost portions of the cap film 21 and the back film 22 in the thickness direction contain the resin (A). The cap film 21 and the back film 22 may be, for example, a single-layer film including the resin layer 1, or a multi-layer film including a first skin layer 11, a core layer 12, and a second skin layer 13.

[0038] When the packaging material in this embodiment is a bubble sheet, it typically has at least one cap film 21 and one back film 22, as in packaging material 20A shown in Figure 3, but it may also have a configuration in which cap film 21 is arranged between two back films 22 and 23, as in packaging material 20B shown in Figure 4.

[0039] The cap film has a plurality of protrusions for trapping air. There are no limitations on the shape of the protrusions provided on the cap film and they can be appropriately selected depending on the intended use of the packaging material. For example, the protrusions can be cylindrical with a diameter of about 5 mm to 100 mm and a height of about 2 mm to 50 mm, and preferably a diameter of about 10 mm to 20 mm and a height of about 3 mm to 10 mm. The arrangement of the protrusions can be the same as that used in known air bubble sheets, for example, a staggered arrangement in which a plurality of protrusions are arranged in a line in the surface direction and the pitch of the protrusions is shifted by half between two adjacent parallel lines.

[0040] The backing film, which is used to form a hollow space together with the capping film and to seal air in the hollow space, is usually flat and does not have any protrusions. The backing film and the capping film are usually bonded together by heat welding.

[0041] As the film material that can be used for the cap film and the back film, a single layer film containing a resin layer containing the above-mentioned resin (A) or a multilayer film containing the above-mentioned resin layer can be used.

[0042] The thickness of the film material used for the cap film can be appropriately selected depending on the application of the packaging material, but is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and is usually less than 200 μm, more preferably 100 μm or less, more preferably 50 μm or less. When the thickness of the film material used for the cap film is within the above range, it can be easily processed into a bubble sheet.

[0043] The thickness of the film material used for the backing film can be appropriately selected depending on the intended use of the packaging material, but is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and is usually less than 200 μm, more preferably 100 μm or less, more preferably 50 μm or less. When the thickness of the film material used for the backing film is within the above range, it can be easily processed into a bubble sheet.

[0044] <2.3. When the packaging material is nonwoven fabric> When the packaging material according to this embodiment is a nonwoven fabric, the nonwoven fabric is typically composed of resin fibers containing resin (A). Since nonwoven fabrics typically allow air to pass through, the surface of the resin fibers corresponds to the outer surface of the packaging material, and the portion of the resin fibers exposed on the surface typically corresponds to the outermost portion of the packaging material in the thickness direction. Typically, the portion of the resin fibers extending a predetermined distance t toward the center (typically, the portion extending 2 μm from the surface toward the center) corresponds to the outermost portion of the packaging material in the thickness direction.

[0045] Fig. 5 is a cross-sectional view schematically showing another example of a packaging material according to one embodiment of the present invention, and Figs. 6 and 7 are perspective views schematically showing one example and another example of resin fibers constituting the packaging material according to one embodiment of the present invention. In this embodiment, the packaging material 30 is a nonwoven fabric made of resin fibers 3, and the resin fibers 3 may be configured to contain a resin (A). As described above, when the packaging material is a nonwoven fabric 30, as shown in Figs. 6 and 7, a portion M3 extending from the outer surface 3S of the resin fiber 3 to a predetermined distance t toward the center 3C of the resin fiber typically corresponds to the outermost portion in the thickness direction of the packaging material 30.

[0046] The resin fibers 3 that the nonwoven fabric may contain may be, for example, single resin fibers 3a containing a single resin, as shown in Figure 6. Furthermore, when the nonwoven fabric contains single resin fibers, it is preferable that the nonwoven fabric contain two or more types of single resin fibers formed from resin (A1) and resin (A2) containing an alicyclic structure-containing polymer and having different glass transition temperatures. This is because a nonwoven fabric with good flexibility can be produced by a wet method using resin fibers containing resin (A1) with a high glass transition temperature as the main fibers and resin fibers containing resin (A2) with a low glass transition temperature as the binder fibers.

[0047] Furthermore, examples of resin fibers 3 that can be contained in the nonwoven fabric include sheath-core fibers 3b in which two or more types of resins are concentrically arranged, as shown in Fig. 7. The sheath-core fibers 3b typically have a sheath portion 31 provided on the outside of the resin fiber and a core portion 32 provided inside the sheath portion 31. In the sheath-core fibers 3b used in this embodiment, typically, at least the sheath portion 31 contains the resin (A), and the sheath portion 31 has a thickness at least equal to or greater than the outermost portion in the thickness direction of the packaging material.

[0048] The cross-sectional shape of the resin fibers is not limited, but can be, for example, circular or elliptical. The average fiber diameter of the resin fibers is not limited, but is usually 6 μm or more, preferably 8 μm or more, more preferably 10 μm or more, and usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. When the resin fibers are in the above range, the flexibility of the nonwoven fabric can be improved.

[0049] When the resin fiber is a core-sheath fiber, the average thickness of the sheath is usually 2 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less. When the average thickness of the sheath is within the above range, the effects of the present invention can be significantly exhibited.

[0050] The average fiber diameter of the resin fiber is the calculated average of the values ​​measured for the fiber diameter of 20 fibers in an electron microscope image of the cross section of the cut packaging material (nonwoven fabric). The average thickness of the sheath portion of the core-sheath fiber is the calculated average of the values ​​measured for the thickness of the sheath portion of 20 fibers in an electron microscope image of the cross section of the cut packaging material (nonwoven fabric).

[0051] The average fiber length of the resin fibers is not limited and can be appropriately selected depending on the intended use of the packaging material, but is usually 2 mm or more, preferably 3 mm or more, more preferably 4 mm or more, and usually 20 mm or less, preferably 15 mm or less, more preferably 10 mm or less, because the flexibility of the nonwoven fabric can be improved by having the resin fibers in this range.

[0052] The average fiber length of the resin fibers is determined by observing the surface of a cut packaging material (nonwoven fabric) under magnification, measuring the fiber lengths of 20 fibers, and calculating the average value.

[0053] There is no limit to the basis weight of the nonwoven fabric used in the packaging material, and it can be selected appropriately depending on the application of the packaging material. 2 or more, preferably 10 g / m 2 More preferably, 15 g / m 2 or more, usually 50 g / m 2 Less than 40 g / m 2 Less than 30 g / m, more preferably 2 The reason is that when the basis weight of the nonwoven fabric is within the above range, it can be used as a packaging material that can provide good protection for articles.

[0054] The thickness of the nonwoven fabric used in the packaging material is not limited and can be appropriately selected depending on the application of the packaging material, but is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and usually 100 μm or less, preferably 80 μm or less, more preferably 50 μm or less. When the thickness of the nonwoven fabric is within the above range, the packaging material can provide good protection for articles.

[0055] <2.4. Modifications> In addition to the above-mentioned films, film processed products (bubble sheets), and nonwoven fabrics, the packaging material according to this embodiment may also be in the form of a substrate such as paper, cloth, or nonwoven fabric on which a resin layer containing resin (A) is provided. Packaging materials of this form can be obtained, for example, by applying a coating liquid containing resin (A) to the substrate. Paper, cloth, and nonwoven fabric substrates that are known to be used as packaging materials can be used.

[0056] <3. Packaging materials> The packaging material contains a resin (A) containing an alicyclic structure-containing polymer at least in the outermost portion in the thickness direction.

[0057] <3.1. Resin (A)> The resin (A) is a resin containing an alicyclic structure-containing polymer, and is usually a thermoplastic resin.

[0058] The resin (A) contains an alicyclic structural polymer, and may contain any optional component as required.

[0059] The alicyclic structure-containing polymer contained in the resin (A) is a polymer containing an alicyclic structure in the repeating unit thereof. The alicyclic structure-containing polymer is usually excellent in mechanical strength, transparency, low water absorption, moisture resistance, dimensional stability, and light weight.

[0060] Examples of the polymer containing an alicyclic structure include a polymer obtainable by a polymerization reaction using a cyclic olefin as a monomer, or a hydrogenated product thereof.The polymer containing an alicyclic structure can be either a polymer containing an alicyclic structure in the main chain or a polymer containing an alicyclic structure in the side chain.Among these, the polymer containing an alicyclic structure preferably contains an alicyclic structure in the main chain.Examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure, and a cycloalkane structure is preferred from the viewpoint of thermal stability, etc.

[0061] The number of carbon atoms contained in one alicyclic structure is preferably 4 or more, more preferably 5 or more, more preferably 6 or more, and is preferably 30 or less, more preferably 20 or less, particularly preferably 15 or less. When the number of carbon atoms contained in one alicyclic structure is within the above range, a high level of balance between mechanical strength, heat resistance, and moldability is achieved.

[0062] The proportion of repeating units having an alicyclic structure in the alicyclic structure-containing polymer is preferably 30% by weight or more, more preferably 50% by weight or more, even more preferably 70% by weight or more, and particularly preferably 90% by weight or more. By increasing the proportion of repeating units having an alicyclic structure as described above, heat resistance can be improved. In the alicyclic structure-containing polymer, the remainder other than the repeating unit having the alicyclic structure is not particularly limited and can be appropriately selected depending on the intended use.

[0063] The alicyclic structure-containing polymer contained in the resin (A) may be an amorphous alicyclic structure-containing polymer, a crystalline alicyclic structure-containing polymer, or a mixture thereof.

[0064] The crystalline nature of an alicyclic structure-containing polymer means that the alicyclic structure-containing polymer has a melting point Tm, more specifically, that the melting point can be observed by a differential scanning calorimeter (DSC). On the other hand, the amorphous nature of an alicyclic structure-containing polymer means that the alicyclic structure-containing polymer does not have a melting point Tm, more specifically, that the melting point cannot be observed by a differential scanning calorimeter (DSC).

[0065] Hereinafter, the "alicyclic structure-containing polymer having amorphous properties" may be referred to as the "amorphous alicyclic structure-containing polymer", and the "alicyclic structure-containing polymer having crystalline properties" may be referred to as the "crystalline alicyclic structure-containing polymer".

[0066] Examples of amorphous polymers containing an alicyclic structure include (1) norbornene polymers, (2) monocyclic olefin polymers, (3) cyclic conjugated diene polymers, (4) vinyl alicyclic hydrocarbon polymers, and hydrogenated versions thereof. Among these, norbornene polymers and hydrogenated versions thereof are preferred from the viewpoints of transparency and moldability.

[0067] Examples of norbornene-based polymers include ring-opening polymers of monomers having a norbornene structure and their hydrogenated products; and addition polymers of monomers having a norbornene structure and their hydrogenated products. Examples of ring-opening polymers of monomers having a norbornene structure include ring-opening homopolymers of one type of monomer having a norbornene structure, ring-opening copolymers of two or more types of monomers having a norbornene structure, and ring-opening copolymers of a monomer having a norbornene structure and any monomer copolymerizable therewith. Examples of addition polymers of monomers having a norbornene structure include addition homopolymers of one type of monomer having a norbornene structure, addition copolymers of two or more types of monomers having a norbornene structure, and addition copolymers of a monomer having a norbornene structure and any monomer copolymerizable therewith. Among these, hydrogenated ring-opening polymers of monomers having a norbornene structure are particularly suitable from the viewpoints of moldability, heat resistance, low moisture absorption, low moisture permeability, dimensional stability, and light weight.

[0068] Examples of monomers having a norbornene structure include bicyclo[2.2.1]hept-2-ene (common name: norbornene), tricyclo[4.3.0.1 2,5 ]Deca-3,7-diene (common name: dicyclopentadiene), 7,8-benzotricyclo[4.3.0.1 2,5 ]dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo[4.4.0.1 2,5 .1 7,10]dodec-3-ene (trivial name: tetracyclododecene) and derivatives of these compounds (for example, those having a substituent on the ring) can be mentioned. Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. These substituents may be the same or different, and a plurality of them may be bonded to the ring. The monomer having a norbornene structure can be used alone or in combination of two or more types in any ratio. In this embodiment, it is preferable that the monomer having a norbornene structure does not have a polar group. This is because the resin (A) can be made to be a resin that is less susceptible to polar compounds that generate acid components and alkaline components.

[0069] A ring-opening polymer of a monomer having a norbornene structure can be produced, for example, by polymerizing or copolymerizing the monomer in the presence of a ring-opening polymerization catalyst.

[0070] An addition polymer of a monomer having a norbornene structure can be produced, for example, by polymerizing or copolymerizing the monomer in the presence of an addition polymerization catalyst.

[0071] The hydrogenated products of the ring-opening polymer and the addition polymer can be produced, for example, by hydrogenating the carbon-carbon unsaturated bonds, preferably to 90% or more, in a solution of the ring-opening polymer and the addition polymer in the presence of a hydrogenation catalyst containing a transition metal such as nickel or palladium.

[0072] The weight-average molecular weight (Mw) of the amorphous alicyclic structure-containing polymer is preferably 10,000 or more, more preferably 15,000 or more, even more preferably 20,000 or more, and is preferably 100,000 or less, more preferably 80,000 or less, even more preferably 50,000 or less. The alicyclic structure-containing polymer having such a weight-average molecular weight has an excellent balance of mechanical strength, moldability, and heat resistance.

[0073] The molecular weight distribution (Mw / Mn) of the amorphous alicyclic structure-containing polymer is preferably 1.2 or more, more preferably 1.5 or more, particularly preferably 1.8 or more, and preferably 3.5 or less, more preferably 3.4 or less, particularly preferably 3.3 or less. When the molecular weight distribution is at least the lower limit of the above range, the productivity of the alicyclic structure-containing polymer can be increased and production costs can be reduced. On the other hand, when it is at most the upper limit, the amount of low-molecular-weight components is reduced, thereby improving the stability of the layer containing the alicyclic structure-containing polymer.

[0074] The weight-average molecular weight Mw and number-average molecular weight Mn of the amorphous alicyclic structure-containing polymer can be measured in polyisoprene equivalent values ​​by gel permeation chromatography (hereinafter abbreviated as "GPC") using cyclohexane as a solvent. If the resin is not soluble in cyclohexane, they can be measured in polystyrene equivalent values ​​by GPC using toluene as a solvent.

[0075] The glass transition temperature of the amorphous alicyclic structure-containing polymer is preferably 50°C or higher, more preferably 70°C or higher, particularly preferably 80°C or higher, and preferably 200°C or lower, more preferably 180°C or lower, particularly preferably 170°C or lower. The glass transition temperature of the alicyclic structure-containing polymer can be measured by differential scanning calorimetry based on JIS K7121. This measurement can be performed under conditions where a sample is heated from room temperature to 200°C at 20°C / min, then cooled to 40°C at 20°C / min, and then heated from 40°C to 200°C at 10°C / min.

[0076] Various commercial products of amorphous alicyclic structure-containing polymers are available on the market. Therefore, resin (A), which is the raw material for packaging materials, can be prepared using these products as they are or by mixing them with other components as needed. An example of such a commercial product is the product name "ZEONOR" (manufactured by Zeon Corporation).

[0077] On the other hand, preferred examples of the crystalline alicyclic structure-containing polymer include the following polymers (α) to (δ): Among these, polymer (β) is particularly preferred because of its excellent heat resistance. Polymer (α): A ring-opening polymer of a cyclic olefin monomer, which is crystalline. Polymer (β): A hydrogenated product of polymer (α) that is crystalline. Polymer (γ): An addition polymer of a cyclic olefin monomer, which has crystallinity. Polymer (δ): A crystalline polymer such as a hydrogenated polymer (γ).

[0078] More specifically, the crystalline alicyclic structure-containing polymer is preferably a crystalline ring-opening polymer of dicyclopentadiene, or a crystalline hydrogenated ring-opening polymer of dicyclopentadiene, and particularly preferably a crystalline hydrogenated ring-opening polymer of dicyclopentadiene. Here, the ring-opening polymer of dicyclopentadiene refers to a polymer in which the proportion of dicyclopentadiene-derived structural units to all structural units is usually 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more, and even more preferably 100% by weight.

[0079] The crystalline alicyclic structure-containing polymer preferably has a syndiotactic structure, and more preferably has a high degree of syndiotactic stereoregularity. This can increase the crystallinity of the polymer, thereby particularly increasing heat resistance. The degree of syndiotactic stereoregularity of the crystalline alicyclic structure-containing polymer can be expressed by the ratio of racemo-dyads in the crystalline alicyclic structure-containing polymer. The specific ratio of racemo-dyads is preferably 51% or more, more preferably 60% or more, and particularly preferably 70% or more. The ratio of racemo-dyads can be measured by the following method.

[0080] The polymer was decomposed by the inverse-gated decoupling method at 200°C using orthodichlorobenzene-d4 as a solvent. 13C-NMR measurement is performed. 13 In the C-NMR analysis, the signal at 43.35 ppm from the meso-dyad and the signal at 43.43 ppm from the racemo-dyad are identified, with the peak at 127.5 ppm from ortho-dichlorobenzene-d4 as the reference shift. Based on the intensity ratio of these signals, the proportion of racemo-dyads in the polymer can be determined.

[0081] The crystalline alicyclic structure-containing polymer may be used alone or in combination of two or more kinds in any ratio.

[0082] A crystalline alicyclic structure-containing polymer can usually have a high degree of crystallinity due to crystallization. The specific range of the degree of crystallinity can be appropriately selected depending on the desired performance, but is preferably 10% or more, more preferably 15% or more, and particularly preferably 30% or more. By making the degree of crystallinity equal to or higher than the lower limit of the above range, high heat resistance can be imparted to the packaging material. The crystallinity of a polymer can be measured by X-ray diffraction.

[0083] The possible numerical ranges of the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the crystalline alicyclic structure-containing polymer may be the same as or different from the possible numerical ranges of the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the amorphous alicyclic structure-containing polymer.

[0084] The melting point Tm of the crystalline alicyclic structure-containing polymer is preferably 200° C. or higher, more preferably 230° C. or higher, particularly preferably 250° C. or higher, and preferably 290° C. or lower. By using a crystalline alicyclic structure-containing polymer having such a melting point Tm, a packaging material with an even better balance between moldability and heat resistance can be obtained.

[0085] The glass transition temperature Tg of the crystalline alicyclic structure-containing polymer is not particularly limited, but is preferably 85°C or higher, preferably 200°C or lower, and more preferably 170°C or lower.

[0086] The crystalline alicyclic structure-containing polymer can be produced by any method, for example, the method described in WO 2016 / 067893.

[0087] The weight proportion of the alicyclic structure-containing polymer contained in the resin (A) is usually 70% by weight or more, more preferably 80% by weight or more, and even more preferably 90% by weight or more, and is usually 100% by weight or less, preferably 99.99% by weight or less, and more preferably 99% by weight or less. When the weight proportion of the total alicyclic structure-containing polymer contained in the resin (A) is within the above range, the resulting packaging material can effectively suppress outgassing containing acid components and alkali components.

[0088] As described above, the alicyclic structure-containing polymer contained in the resin (A) may be a crystalline alicyclic structure-containing polymer, an amorphous alicyclic structure-containing polymer, or a mixture thereof. The packaging material is prone to adhesion of sebum from bare hands during use, which may cause deterioration of the packaging material. Therefore, from the viewpoint of improving the oil resistance of the packaging material, it is preferable that the resin (A) contains a crystalline alicyclic structure-containing polymer.

[0089] When the total amount of alicyclic structure-containing polymers contained in resin (A) is taken as 100% by weight, the weight proportion of the crystalline alicyclic structure-containing polymer is preferably 30% by weight or more, more preferably 35% by weight or more, even more preferably 40% by weight or more, and preferably 60% by weight or less, more preferably 55% by weight or less, and more preferably 50% by weight or less. Having the weight proportion of the crystalline alicyclic structure-containing polymer at or above the lower limit can improve the oil resistance of the packaging material. Having the weight proportion of the crystalline alicyclic structure-containing polymer at or below the upper limit can effectively suppress the release of outgassing, particularly formic acid. The total amount of alicyclic structure-containing polymers contained in resin (A) is the sum of the content of the crystalline alicyclic structure-containing polymer and the content of the amorphous alicyclic structure-containing polymer contained in resin (A).

[0090] The resin (A) contains the above-described alicyclic structure-containing polymer and may contain optional components as needed. Examples of optional components that the resin (A) may contain include stabilizers such as colorants, antioxidants, UV absorbers, and light stabilizers; resin modifiers such as lubricants and plasticizers; and antistatic agents. In this embodiment, the optional components contained in the resin (A) are preferably components that do not contain carboxylic acids or ester bonds. This is because this can prevent formic acid and acetic acid from being generated as decomposition products of the resin due to heating or the like during the production of the packaging material.

[0091] In this embodiment, since resin (A) is contained in a portion that may come into contact with an article, such as the outermost portion of a packaging material, taking into consideration the effect of the optional components on the article, the lower the content of optional components contained in resin (A) the better, and it is particularly preferable that resin (A) contains no optional components. The weight percentage of optional components in resin (A) is preferably 5% by weight or less, more preferably 3% by weight or less, even more preferably 1% by weight or less, and is usually 0% by weight or more.

[0092] Resin (A) typically has the property of releasing little outgassing, including acid and alkaline components. In particular, resin (A) has the property of detecting a small amount of at least one of acetic acid, formic acid, sodium ions, and calcium ions. Specifically, resin (A) typically has a detectable amount of at least one of acetic acid, formic acid, sodium ions, and calcium ions of 1 μg / g or less. In this embodiment, it is preferable that all of the detectable amounts of acetic acid, formic acid, sodium ions, and calcium ions are 1 μg / g or less. This is because deterioration of an article packaged in the packaging material due to components such as acetic acid, formic acid, sodium ions, and calcium ions can be effectively prevented.

[0093] The detectable amount of acetic acid in resin (A) is usually 1 μg / g or less, preferably 0.8 μg / g or less, more preferably 0.6 μg / g or less, and particularly preferably 0 μg / g. The detectable amount of formic acid in resin (A) is usually 1 μg / g or less, preferably 0.5 μg / g or less, more preferably 0.3 μg / g or less, and particularly preferably 0 μg / g. The detectable amount of sodium ions in resin (A) is usually 1 μg / g or less, preferably 0.3 μg / g or less, more preferably 0.1 μg / g or less, and particularly preferably 0 μg / g. The detectable amount of calcium ions in resin (A) is usually 1 μg / g or less, preferably 0.5 μg / g or less, more preferably 0.3 μg / g or less, and particularly preferably 0 μg / g.

[0094] The amounts of acetic acid, formic acid, sodium ions, and calcium ions detected in resin (A) are measured by the following method. 0.5 g of a sample is weighed into a Teflon (registered trademark) container, 15 mL of ultrapure water is added, the container is sealed, and the target component is extracted by heating at 100°C for 24 hours. The resulting extract is then analyzed by ion chromatography, whereby the amounts of acetic acid, formic acid, sodium ions, and calcium ions detected in 1 g of sample can be measured.

[0095] <3.2. Resin (B)> When the packaging material has the above-mentioned multilayer film or is a nonwoven fabric made of core-sheath fibers, the core layer of the multilayer film or the core of the core-sheath fibers usually contains resin (B).

[0096] The resin (B) contains a polymer and, if necessary, an optional component. The polymer that can be contained in resin (B) is not limited as long as it can form a packaging material together with resin (A), and may contain an alicyclic structure-containing polymer or a polymer other than the alicyclic structure-containing polymer, but in consideration of adhesion to resin (A), it is preferable that the resin (B) contains an alicyclic structure-containing polymer. Resin (B) is usually a thermoplastic resin.

[0097] The alicyclic structure-containing polymer contained in the resin (B) may be a crystalline alicyclic structure-containing polymer, an amorphous alicyclic structure-containing polymer, or a mixture thereof. Among these, the alicyclic structure-containing polymer contained in the resin (B) preferably contains an amorphous alicyclic structure-containing polymer.

[0098] When the total amount of the alicyclic structure-containing polymers contained in the resin (B) is taken as 100% by weight, the weight ratio of the amorphous alicyclic structure-containing polymer is preferably 70% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, and is preferably 100% by weight or less, more preferably 99.99% by weight or more, more preferably 99% by weight or less. This is because, when the weight ratio of the amorphous alicyclic structure-containing polymer is in the above range, production costs can be reduced.

[0099] Furthermore, resin (B) may contain optional components or may not contain optional components, but the former is more preferred because it can impart various functions to the packaging material. The optional components contained in resin (B) may be the same components as those described as optional components contained in resin (A).

[0100] Furthermore, the optional components that may be contained in the resin (B) are preferably an ultraviolet absorber, a light-resistant agent (light stabilizer), and a colorant, and more preferably an ultraviolet absorber and a colorant, because they can impart ultraviolet absorbing, light-resistant, and light-blocking functions to the packaging material, thereby suppressing photodegradation of the article packaged in the packaging material due to ultraviolet rays and the like.

[0101] The ultraviolet absorber that can be contained in the resin (B) can be appropriately selected depending on the intended use of the packaging material, but, for example, it is preferable that it can absorb ultraviolet rays in the wavelength range of at least 380 nm or more and 410 nm or less, because this can improve the transparency of the packaging material.

[0102] The ultraviolet absorber can be appropriately selected from known materials, and examples thereof include triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and indole-based ultraviolet absorbers.

[0103] Commercially available ultraviolet absorbers can also be used, and preferred commercially available products include, for example, Adeka STAB LA-31RG and Adeka STAB LA-F70 manufactured by ADEKA, and Bonasorb UA-3912 manufactured by Orient Scientific.

[0104] The above-mentioned ultraviolet absorbents may be used alone or in combination of two or more.

[0105] The light-resistant additive may be selected from known materials as appropriate, for example, a hindered amine-based light-resistant additive. Commercially available light-resistant additives may also be used, and preferred examples of commercially available light-resistant additives include "ADK STAB LA-57G" and "ADK STAB LA-52SC" manufactured by ADEKA, and "KIMASORB 2020FDL" manufactured by BASF Japan Ltd.

[0106] A colorant is an effective component when high light-blocking properties are required. A black colorant is usually used as the colorant. Various black colorants, such as dyes, pigments, carbon nanotubes, and bamboo charcoal, can be used depending on the application, but dyes are preferred.

[0107] Specific examples of black dyes include Sumiplast Black G-2, Sumiplast Black H3B, Sumiplast Black HLG, and Sumiplast Black HB, all manufactured by Sumitomo Chemtex Co., Ltd.; Black S, Black SF, Black 109, and Black 141, all manufactured by Chuo Synthetic Chemical Industry Co., Ltd.; VALIFAST BLACK 1815, VALIFAST BLACK 1821, OIL BLACK 860, NUBIAN BLACK PC-5857, 5877, and 5856, NUBIAN BLACK PC-0855, NUBIAN BLACK NH-805, 815, NUBIAN BLACK TN-870, 877, and 807, all manufactured by Orient Chemical Industry Co., Ltd.; and Plast Black 8950-N, Plast Black 8970, and Oil Black DA-411, all manufactured by Arimoto Chemical Industry Co., Ltd. Specific examples of black pigments include NUBIAN GREY IR-B and OPLAS BLACK 838 manufactured by Orient Chemical Industry Co., Ltd.; carbon black, particularly carbon black having an arithmetic mean diameter of 5 to 60 nm (preferably 10 to 50 nm) determined by observing carbon black particles under an electron microscope (e.g., SEAST and Aqua Black manufactured by Tokai Carbon Co., Ltd.; BLACK PEARLS, ELFTEX, VULCAN, MOGUL, MONARCH, EMPORER, REGAL, UNITED, SPHERON, STERLING, and SHOWBLACK manufactured by Cabot Corporation; HCF, MCF, RCF, LFF, and SCF series manufactured by Mitsubishi Chemical Corporation; and NITERON and HTC manufactured by Nippon Steel Carbon Co., Ltd.).

[0108] In this embodiment, both a black dye (organic) and a black pigment (inorganic) can be used. In this case, they can be added and mixed directly, or a high concentration product (for example, about 50% by weight) can be prepared as a master batch and then mixed.

[0109] The weight proportion of the optional components contained in resin (B) can be selected appropriately depending on the intended use of the packaging material, but is usually 0.5% by weight or more, preferably 1% by weight or more, more preferably 1.5% by weight or more, and usually 20% by weight or less, preferably 15% by weight or less, more preferably 10% by weight or less. This is because the weight proportion of the optional components in the above range can impart desired functions to resin (B).

[0110] <4. Packaging material manufacturing method> The method for producing the packaging material according to this embodiment is not particularly limited as long as it can produce a packaging material having a desired shape. For example, a production method including the following step (1) is preferred.

[0111] Step (1): A step of molding a resin (A) containing an alicyclic structure-containing polymer at a molding temperature higher than the boiling point of acetic acid.

[0112] By including step (1), resin (A) containing an alicyclic structure-containing polymer is molded at a molding temperature higher than the boiling point of acetic acid, so that acetic acid, formic acid having a boiling point lower than that of acetic acid, and water contained in the material can be removed, and therefore a packaging material can be produced that generates very little outgassing, including formic acid, acetic acid, sodium ions, and calcium ions.

[0113] As described above, preferred forms of the packaging material according to this embodiment include films, processed films, and nonwoven fabrics, and therefore the manufacturing methods for each form will be described below.

[0114] <4.1. When the packaging material is film> When the packaging material is in the form of a film, the film is usually formed in step (1).

[0115] The resin (A) used in step (1) is usually the same resin as the resin (A) that may be contained in the packaging material described above. The resin (A) is preferably processed into a pellet-like resin.

[0116] A "pellet-like" resin is a solid resin in a granular form. The specific shape of the pellets is generally an approximately cylindrical shape obtained by cutting a strand, but the present invention is not limited to this, and pellets of any shape can be used. The term "approximately cylindrical" includes not only a strict cylindrical shape, but also a cylinder with an elliptical base and a cylinder with a circular base and a so-called disk shape in which the height is smaller than the base diameter.

[0117] When the pelletized resin is roughly cylindrical, its dimensions may be, for example, a number average diameter of about 1 mm or more and 7 mm or less, and a number average length of about 4 mm or more and 8 mm or less.

[0118] The pellet-shaped resin can be produced, for example, by melting the resin (A) containing the alicyclic structure-containing polymer, extruding it into a strand shape of a predetermined diameter, and then chopping it into pellets of the desired length using an appropriate strand cutter.

[0119] When forming a multilayer film in step (1), the above-mentioned resin (B) may be used together with the resin (A). The resin (B) is usually the same resin as the resin (B) that may be contained in the packaging material. The resin (B) is also preferably processed into a pellet-shaped resin.

[0120] Any film molding method can be used to mold the resin (A), but when the film is a single-layer film, melt extrusion is preferred because it does not use a solvent. Examples of melt extrusion methods include inflation methods using a die, and among these, methods using a T-die are preferred because of their excellent productivity and thickness accuracy. Furthermore, when the film is a multilayer film, coextrusion molding methods such as coextrusion T-die method, coextrusion inflation method, and coextrusion lamination method are preferred, and among these, coextrusion T-die method is preferred.

[0121] The molding temperature of resin (A) is higher than the boiling point of acetic acid (118°C). This is because adjusting the molding temperature based on the boiling point of acetic acid allows formic acid (boiling point of formic acid: 101°C) and water (boiling point of water: 100°C), which have lower boiling points than acetic acid, to be removed. The molding temperature of resin (A) is usually higher than the boiling point of acetic acid, preferably at least (the boiling point of acetic acid + 83°C), more preferably at least (the boiling point of acetic acid + 100°C), and even more preferably at least (the boiling point of acetic acid + 150°C). The molding temperature of the resin is usually at most (the boiling point of acetic acid + 200°C), preferably at most (the boiling point of acetic acid + 183°C), more preferably at most (the boiling point of acetic acid + 180°C), and even more preferably at most (the boiling point of acetic acid + 160°C). This range corresponds to the range from at least (the boiling point of formic acid + 100°C) to at most (the boiling point of formic acid + 217°C). When the molding temperature of the resin (A) is equal to or higher than the lower limit, water, formic acid, and acetic acid in the resin (A) can be removed, and when the molding temperature of the resin is equal to or lower than the upper limit, denaturation of the resin due to heating can be suppressed. The molding temperature of the resin (A) refers to the temperature of the resin (A) (molten resin) during molding.

[0122] The method for producing a packaging material may, if necessary, include step (2) of drying the resin (A) containing the alicyclic structure-containing polymer before step (1). Step (2) is a step of drying the alicyclic structure-containing polymer at a temperature of (Tg-60)°C or higher and (Tg-10)°C, where Tg (°C) is the glass transition temperature of the resin (A) containing the alicyclic structure-containing polymer.

[0123] In step (2), the resin (A) containing the alicyclic structure-containing polymer is dried. In step (2), it is preferable to dry the above-mentioned resin in the form of pellets.

[0124] The drying temperature of the resin (A) is equal to or lower than the glass transition temperature (Tg) of the resin (A) containing the alicyclic structure-containing polymer. Specifically, it is equal to or higher than (Tg - 60°C), preferably equal to or higher than (Tg - 50°C), more preferably equal to or higher than (Tg - 40°C), and equal to or lower than (Tg - 10°C), preferably equal to or lower than (Tg - 15°C), and more preferably equal to or lower than (Tg - 20°C). By keeping the drying temperature equal to or lower than the upper limit, thermal fusion between pellets can be suppressed, making the pellets easier to handle. Furthermore, by keeping the drying temperature equal to or higher than the lower limit, evaporation of formic acid and acetic acid in the pellets can be promoted. The glass transition temperature (Tg) of the resin (A) containing the alicyclic structure-containing polymer can be measured by the same method as that for the glass transition temperature of the alicyclic structure-containing polymer described above.

[0125] The drying time for the resin (A) is preferably 1 hour or more, preferably 1.5 hours or more, and more preferably 2 hours or more. The drying time may be, for example, 10 hours or less, preferably 8 hours or less, and more preferably 5 hours or less. This is because a drying time within the above range can promote evaporation of formic acid and acetic acid from the resin.

[0126] The drying treatment in step (2) may be, for example, vacuum drying treatment, reduced pressure drying treatment in an air or nitrogen atmosphere, or normal pressure drying in an air or nitrogen atmosphere.

[0127] The resin dried in step (2) can be stored in step (1) for several days after the drying, but the effect of step (B) is not lost. The shorter the storage period, the better. The storage period of the dried resin pellets at room temperature and normal pressure (23°C, approximately 1 atmosphere) is preferably within 5 days, more preferably within 3 days, and even more preferably within 1 day.

[0128] <4.2. When the packaging material is a film-processed product> When the packaging material is a processed film, a film is usually formed in step (1), and step (3) is usually included in which the film obtained in step (1) is processed to obtain a packaging material that is a processed film.

[0129] When the processed film is a bubble sheet, step (3) typically includes forming a concave-convex shape on the film obtained in step (1) to obtain a cap film having protrusions, and heat-welding the cap film and backing film to obtain a bubble sheet. The method for forming the concave-convex shape on the film to obtain the cap film is the same as that used in known bubble sheet manufacturing methods, such as vacuum molding using a roll with a concave-convex shape on its outer peripheral surface. Furthermore, the same method as that used in known bubble sheet manufacturing methods can be used for heat-welding the cap film and backing film. For example, the manufacturing method described in Patent Document 1 can also be used to manufacture the bubble sheet.

[0130] <4.3. When the packaging material is nonwoven fabric> When the packaging material is a processed film, resin fibers are usually formed in step (1), and the process usually includes step (4) of forming a nonwoven fabric using the resin fibers obtained in step (1).

[0131] The form of the resin fibers formed in step (1) is appropriately selected depending on the method for forming the nonwoven fabric used in step (4). Any method can be used to form the nonwoven fabric, including, for example, a wet method, a dry method, a spunbond method, and a flash spinning method. In this embodiment, the wet method is preferred. This is because a wet-laid nonwoven fabric formed using a wet method can shorten the length of the resin fibers constituting the nonwoven fabric, resulting in a nonwoven fabric with good flexibility, which can be used as a packaging material that is easy to use for packaging goods.

[0132] When a wet process is used, it is preferable to form the resin fiber in step (1) from, for example, a subject fiber and a binder fiber having a glass transition temperature lower than that of the subject fiber. In this case, both the subject fiber and the binder fiber are formed from a resin (A) containing an alicyclic structure-containing polymer. The resin fiber may also be a core-sheath fiber. As a method for forming resin fibers, a melt spinning method is usually used.

[0133] In step (4), a nonwoven fabric is formed using the resin fibers obtained in step (1). Known methods can be used to produce the nonwoven fabric. For example, when forming a nonwoven fabric by a wet method, a mixed solution is typically prepared by mixing resin fibers with water, and a film of the mixed solution is formed using a short-wire paper machine or the like, followed by drying to obtain the nonwoven fabric. Examples of methods for producing wet-laid nonwoven fabrics include those described in JP 2004-181341 A. The drying temperature for the wet-laid nonwoven fabric is appropriately adjusted depending on whether or not a reduced pressure is applied during drying, but it is preferably carried out at a temperature higher than the boiling point of acetic acid. Furthermore, since the resin fibers are typically thermally fused together during the drying process of the wet-laid nonwoven fabric, it is preferably carried out at a temperature within a range of about ±30°C of the glass transition temperature Tg of the resin (A).

[0134] <4.4. Modifications> When the packaging material according to the present embodiment includes a multilayer film or a resin layer containing resin (A) provided on a substrate, a method for producing the packaging material may include, for example, applying a coating liquid containing resin (A) and a solvent to a film material or substrate that can serve as a core layer to form a coating layer, and drying the coating layer to form a resin layer. In this case, it is preferable to dry the coating layer by heating at a temperature higher than the boiling point of acetic acid, for example. This is because a packaging material in which outgassing is effectively suppressed can be obtained.

[0135] <5. Uses of packaging materials> The packaging material according to the present embodiment is typically used to package an item. In addition, in the present embodiment, the packaging material is preferably used to preserve the item. Conventional packaging materials tend to continuously release small amounts of outgassing over a long period of time. Therefore, when used to preserve an item, there is a concern that the outgassing from the packaging material may cause the item to deteriorate over time. In contrast, the packaging material according to the present embodiment suppresses outgassing, thereby suppressing deterioration of the item over time during storage.

[0136] Therefore, in this embodiment, a method for preserving an item can be provided, which involves packaging the item using a packaging material and preserving the resulting package, wherein the packaging material is the packaging material described above.

[0137] Because the packaging material according to the present embodiment can suppress outgassing, it is preferably used as a packaging material for items that must be handled while strictly controlling the acid and alkaline components in the air. Specifically, it is preferably used as a packaging material for artworks, semiconductor products, electronic products, aerospace equipment, etc., and is particularly preferably used as a packaging material for artworks.

[0138] The packaging materials used for artworks can be any of the above-mentioned films, processed films, and nonwoven fabrics, but bubble sheets and nonwoven fabrics are preferred. This is because artworks tend to be vulnerable to physical impacts and their value tends to decrease significantly due to scratches, so it is preferable to use packaging materials that have a high cushioning function.

[0139] When packaging an item using the packaging material according to the present embodiment, the item is typically packaged by hand, but it is preferable to wear gloves. This is because this can prevent deterioration of the packaging material due to sebum. Normally, for items that require strict control of acid and alkaline components in the air, it is desirable to minimize adhesion of sebum and other substances, and bare-handed contact with the item is often prohibited. Therefore, when the packaging material according to the present embodiment is used for such items, deterioration of the packaging material itself can be prevented by using the packaging material in accordance with the handling requirements of these items. [Example]

[0140] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the examples shown below, and can be implemented with any modifications within the scope of the claims of the present invention and their equivalents.

[0141] In the following description, the units "%" and "parts" that represent amounts are by weight unless otherwise specified. Furthermore, the operations described below were carried out in air at room temperature and normal pressure (23°C, 1 atmosphere) unless otherwise specified.

[0142] [Evaluation method] <Method for measuring the hydrogenation rate of polymer> The hydrogenation rate of the polymer was measured by 1H-NMR measurement at 145°C using orthodichlorobenzene-d4 as a solvent.

[0143] <Method for measuring weight average molecular weight (Mw) and number average molecular weight (Mn) of polymer> The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polymer were measured as polystyrene equivalent values ​​using a gel permeation chromatography (GPC) system (Tosoh Corporation, "HLC-8320"). The measurement was performed using an H-type column (Tosoh Corporation) and tetrahydrofuran as the solvent. The temperature during measurement was 40°C.

[0144] <Method for measuring the racemo-dyad ratio of polymers> The racemo-dyad ratio of the polymer was determined as follows. The polymer was analyzed by 13C-NMR at 200°C using orthodichlorobenzene-d4 as the solvent, applying the inverse-gated decoupling method. The 13C-NMR results identified a signal at 43.35 ppm from the meso-dyad and a signal at 43.43 ppm from the racemo-dyad, with the peak at 127.5 ppm from orthodichlorobenzene-d4 as the reference shift. The ratio of the racemo-dyads in the polymer was calculated based on the intensity ratio of these signals.

[0145] <Method for measuring the glass transition temperature Tg and melting point Tm of a polymer> The glass transition temperature Tg and melting point Tm of the polymer were measured as follows. The polymer sample was melted by heating and then rapidly cooled with dry ice.The glass transition temperature (Tg) and melting point (Tm) of the sample were then measured using a differential scanning calorimeter (DSC) at a heating rate of 10°C / min (heating mode).

[0146] <Method for measuring polymer melt mass flow rate> The melt mass flow rate of the polymer was measured in accordance with JIS K7210 using a melt indexer ("F-F01" manufactured by Toyo Seiki Seisaku-sho, Ltd.) at a temperature of 280°C and a load of 2.16 kg.

[0147] <Outgassing test> A 0.5 g sample was cut out from the packaging material of each of the Examples and Comparative Examples, weighed into a Teflon (registered trademark) container, and then 15 mL of ultrapure water was added, the container was sealed, and heated at 100°C for 24 hours to extract the target components. The resulting extract was then analyzed by ion chromatography, and the amounts of acetic acid, formic acid, sodium ions, and calcium ions extracted per 1 g of sample were determined as the detected amounts.

[0148] When the packaging material was a multilayer film having a skin layer, a core layer and another skin layer, the material used for the skin layer was used as a sample, and the amount of extraction of each of the above-mentioned components was determined as the detected amount.

[0149] The amount of outgassing detected from the packaging material was evaluated according to the following index. A: The extracted amounts of acetic acid, formic acid, sodium ions, and calcium ions are all below the detection limit. B: The extractable amounts of acetic acid, formic acid, sodium ions, and calcium ions are all 1 μg / g or less. C: B: At least one of the extractable amounts of acetic acid, formic acid, sodium ion, and calcium ion exceeds 1 μg / g

[0150] <Oil resistance test> The packaging materials of Examples 1 to 9 and Comparative Example 1 were cut to a size of 5 cm in the MD x 2 cm in the TD. They were clamped with clips so that the fold was parallel to the TD, and the bent part had a radius of approximately 2.5 mm. A drop of n-hexane was dropped on the bent part, and the clip was removed. If the film in contact with the n-hexane was penetrated, it was judged to have no oil resistance; if it was not penetrated, it was judged to have oil resistance. As an overall evaluation of the packaging material, if both the cap film side and the back film side had oil resistance, it was rated as having oil resistance, and if at least one of the cap film side and the back film side did not have oil resistance, it was rated as not having oil resistance.

[0151] <Light transmittance> The light transmittance of the bubble sheet was measured using a UV-Vis-NIR spectrophotometer (JASCO Corporation, "V-7200"). The data acquisition interval during measurement was 1 nm. From the obtained spectrum, the light transmittance at wavelengths of 380 nm, 410 nm, 470 nm, 530 nm, and 620 nm was read.

[0152] [Production Example 1: Production of Resin (X) Containing Crystalline Polymer (X)] A crystalline polymer (X), which is a crystalline polymer containing an alicyclic structure, was produced by the following procedure. A metal pressure reactor was thoroughly dried and then purged with nitrogen. 154.5 parts of cyclohexane, 42.8 parts of a 70% cyclohexane solution of dicyclopentadiene (endo isomer content of 99% or more) (30 parts as dicyclopentadiene), and 1.8 parts of 1-hexene were added to the pressure reactor and heated to 53°C.

[0153] A catalyst solution was prepared by adding 0.061 parts of a 19% diethylaluminum ethoxide / n-hexane solution to a solution of 0.014 parts of tetrachlorotungsten phenylimide (tetrahydrofuran) complex dissolved in 0.70 parts of toluene and stirring for 10 minutes. This catalyst solution was added to the pressure-resistant reactor to initiate the ring-opening polymerization reaction. The reaction was then continued for 4 hours while maintaining the temperature at 53°C, yielding a solution of a ring-opening polymer of dicyclopentadiene.

[0154] The number average molecular weight (Mn) and weight average molecular weight (Mw) of the obtained ring-opened polymer of dicyclopentadiene were 8,830 and 29,800, respectively, and the molecular weight distribution (Mw / Mn) calculated from these was 3.37.

[0155] To 200 parts of the resulting solution of ring-opened dicyclopentadiene polymer, 0.037 parts of 1,2-ethanediol was added as a terminator, heated to 60 ° C, and stirred for 1 hour to terminate the polymerization reaction. One part of a hydrotalcite-like compound (Kyowa Chemical Industry Co., Ltd.'s "Kyoward (registered trademark) 2000") was added, heated to 60 ° C, and stirred for 1 hour. Then, 0.4 parts of a filter aid (Showa Chemical Industry Co., Ltd.'s "Radiolite (registered trademark) #1500") was added, and the adsorbent and the solution were filtered using a PP pleated cartridge filter (Advantec Toyo Co., Ltd.'s "TCP-HX").

[0156] To 200 parts of the filtered dicyclopentadiene ring-opening polymer solution (30 parts polymer), 100 parts of cyclohexane was added, and 0.0043 parts of chlorohydridocarbonyltris(triphenylphosphine)ruthenium was added, followed by a hydrogenation reaction at 180°C and a hydrogen pressure of 6 MPa for 4 hours. This yielded a reaction solution containing a hydride of the dicyclopentadiene ring-opening polymer. This reaction solution had become a slurry solution due to precipitation of the hydride.

[0157] The hydrogenated product and the solution contained in the reaction mixture were separated using a centrifuge and dried under reduced pressure at 60°C for 24 hours to obtain 28.5 parts of a crystalline hydrogenated ring-opening polymer of dicyclopentadiene as crystalline polymer (X). The hydrogenation rate of crystalline polymer (X) was confirmed to be 99% or higher, and it had a glass transition temperature (Tg) of 97°C, a melting point (Tm) of 266°C, a racemo-dyad ratio of 89%, and a melt mass flow rate of 17g / 10min at 280°C and a load of 2.16kg.

[0158] The obtained crystalline polymer (X) was extruded in the form of a strand from a twin-screw extruder and molded with a pelletizer to obtain pellets of a resin (X) containing the crystalline polymer (X).

[0159] [Production Example 2: Production of Resin (Y) Containing Amorphous Polymer (Y)] As the amorphous polymer (Y), which is an amorphous alicyclic structure-containing polymer, "ZEONOR 1600" (glass transition temperature 162°C) manufactured by Zeon Corporation was prepared. The melt mass flow rate of this polymer at a temperature of 280°C and a load of 2.16 kg was 7 g / 10 min.

[0160] The amorphous polymer (Y) was extruded in the form of a strand from a twin-screw extruder and molded with a pelletizer to obtain pellets of the amorphous polymer (Y).

[0161] [Example 1] (Manufacturing of monolayer film) The material used for the monolayer film was the resin (X) obtained in Production Example 1. Since the resin (X) contains 100% crystalline polymer (X) as the alicyclic structure-containing polymer, it corresponds to the resin (A).

[0162] Pellets of resin (X) were fed into a single-screw extruder, extruded through a T-die onto a casting drum in the form of a sheet, and cooled to obtain a monolayer film with a thickness of 30 μm. The processing temperature of the single-screw extruder was 280°C, and the cooling temperature of the casting drum was 90°C.

[0163] Two monolayer films were produced using the above procedure, one of which was used as a cap film by processing described below, and the other monolayer film was used as a back film.

[0164] (Cap film manufacturing) The resulting monolayer film was then subjected to a vacuum forming process using a roll with an uneven outer surface to form cylindrical protrusions, each with a diameter of 10 mm and a height of 3.5 mm.

[0165] (Bubble sheet manufacturing) The resulting cap film and back film were heat-sealed to obtain a bubble sheet.

[0166] [Example 2] A mixed resin containing 80% resin (X) and 20% resin (Y) was used as the material for the monolayer film for the cap film. This mixed resin contains 80% crystalline polymer (X) and 20% amorphous polymer (Y) as the alicyclic structure-containing polymer, so it corresponds to resin (A). A bubble sheet was produced in the same manner as in Example 1, except that the material for the monolayer film for the cap film was changed.

[0167] [Example 3] A mixed resin containing 50% resin (X) and 50% resin (Y) was used as the material for the monolayer film for the cap film. This mixed resin contains 50% crystalline polymer (X) and 50% amorphous polymer (Y) as the alicyclic structure-containing polymer, so it corresponds to resin (A). A bubble sheet was produced in the same manner as in Example 1, except that the material for the monolayer film for the cap film was changed.

[0168] [Example 4] A mixed resin containing 40% resin (X) and 60% resin (Y) was used as the material for the monolayer film for the cap film. This mixed resin contains 40% crystalline polymer (X) and 60% amorphous polymer (Y) as the alicyclic structure-containing polymer, so it corresponds to resin (A). A bubble sheet was produced in the same manner as in Example 1, except that the material for the monolayer film for the cap film was changed.

[0169] [Example 5] A mixed resin containing 20% ​​resin (X) and 80% resin (Y) was used as the material for the monolayer film for the cap film. This mixed resin contains 20% crystalline polymer (X) and 80% amorphous polymer (Y) as the alicyclic structure-containing polymer, so it corresponds to resin (A). A bubble sheet was produced in the same manner as in Example 1, except that the material for the monolayer film for the cap film was changed.

[0170] [Example 6] A resin containing 100% of resin (Y) was used as the material for the monolayer film for the cap film. This resin (Y) corresponds to resin (A) because it contains 100% of amorphous polymer (Y) as an alicyclic structure-containing polymer. A bubble sheet was produced in the same manner as in Example 1, except that the material of the monolayer film for the cap film was changed.

[0171] [Example 7] The material for the cap film monolayer film and the back film monolayer film was a resin containing 100% resin (Y). Except for changing the material for the cap film monolayer film and the back film monolayer film, the air bubble sheet was produced in the same manner as in Example 1.

[0172] [Example 8] A mixed resin containing 50% of resin (X) and 50% of resin (Y) was used as the material for the monolayer film for the back film. Except for changing the material of the monolayer film for the back film, an air bubble sheet was produced in the same manner as in Example 1.

[0173] [Example 9] A mixed resin containing 70% of resin (X) and 30% of resin (Y) was used as the material for the monolayer film for the cap film. This mixed resin contains 70% of crystalline polymer (X) and 30% of amorphous polymer (Y) as the alicyclic structure-containing polymer, and therefore corresponds to resin (A). A mixed resin containing 30% of resin (X) and 70% of resin (Y) was used as the material for the monolayer film for the back film. This mixed resin contains 30% of crystalline polymer (X) and 70% of amorphous polymer (Y) as the alicyclic structure-containing polymer, and therefore corresponds to resin (A). A bubble sheet was produced in the same manner as in Example 1, except that the materials of the monolayer film for the cap film and the monolayer film for the back film were changed.

[0174] [Example 10] A bubble sheet was produced in the same manner as in Example 1, except that a multilayer film having a first skin layer, a core layer, and a second skin layer, produced by the following procedure, was used as the film material for the cap film.

[0175] As the resin for forming the core layer, 95 parts of amorphous polymer (Y) and 5 parts of an ultraviolet absorber (ADEKA CORPORATION's "ADEKA STAB LA-31" (2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol]) were supplied to a co-rotating twin-screw extruder (The Japan Steel Works, Ltd.'s "TEX-44αII", inner diameter DΦ=25 mm, barrel length L / D=42) and kneaded at a kneading temperature of 280°C to obtain resin (B1) for the core layer. Resin (B1) was extruded from the twin-screw extruder in the form of a strand and molded using a pelletizer to obtain pellets of resin (B1).

[0176] Resin (X) was used as the resin for forming the first skin layer and the second skin layer.

[0177] A laminated film was produced by coextrusion using a two-type, three-layer multilayer extruder (manufactured by Shibaura Machine Co., Ltd.) equipped with a feed block. The feed block was designed to form a laminate having a three-layer structure consisting of a first skin layer, a core layer, and a second skin layer. The feed block was connected to a first single-screw extruder for melting the resin for forming the core layer to obtain a molten resin and extruding it, and a second single-screw extruder for melting the resin for forming the first and second skin layers to obtain a molten resin and extruding it. Pellets of resin (B1) were supplied to the first single-screw extruder as the resin for the core layer, and pellets of resin (X) were supplied to the second single-screw extruder as the resin for the first and second skin layers. The laminated molten resin was extruded from a die connected to the feed block onto a cooling roll and cooled, resulting in a laminated film having a first skin layer, a core layer, and a second skin layer in this order. The resin temperature during extrusion was 280°C, and the cooling roll temperature was 90°C. The extrusion conditions were adjusted so that the thickness of each of the first skin layer, the core layer, and the second skin layer was 10 μm, and the total thickness of the multilayer film was 30 μm.

[0178] [Example 11] An air bubble sheet was produced in the same manner as in Example 10, except that the ultraviolet absorber used in the core layer of the multilayer film for the cap film was changed from ADEKA Corporation's "ADEKA STAB LA-31" to Orient Chemical Industry's "Vonasorb (registered trademark)."

[0179] [Example 12] An air bubble sheet was produced in the same manner as in Example 10, except that the ultraviolet absorber used for the core layer of the multilayer film for the cap film was changed from ADEKA Corporation's "ADEKA STAB LA-31" to Orient Chemical Industry's "NUBIAN BLACK PC-5857."

[0180] [Example 13] A wet-laid nonwoven fabric was produced according to the following procedure. Pellets of resin (X) were used as the resin for the main fibers, and pellets of resin (Y) were used as the binder fibers.

[0181] Each pellet was dried at 110°C for 4 hours.

[0182] The dried resin (X) pellets were fed to a melt spinning apparatus using a spinneret with 900 holes, and taken up under conditions of a spinning temperature of 280°C, a discharge rate of 400 g / min, and a spinning speed of 600 m / min to obtain an undrawn yarn. The obtained undrawn yarn was drawn 3 times to obtain a main fiber. The dried resin (Y) pellets were also spun and drawn under the same conditions as those for producing the main fiber to obtain binder fibers.

[0183] The paper was made with 70% main fiber and 30% binder fiber on a short wire paper machine and dried in a dryer at 120°C to produce a paper with a basis weight of 15 g / m 2 A nonwoven fabric having a thickness of 0.03 mm was obtained by the above method. This nonwoven fabric contains subject fibers containing a crystalline polymer (X) as the alicyclic structure-containing polymer and binder fibers containing an amorphous polymer (Y), and therefore the subject fibers and binder fibers correspond to resin fibers containing a resin (A).

[0184] [Comparative Example 1] A bubble wrap sheet ("PuchiPuchi (registered trademark)" manufactured by Kawakami Industries) was prepared, with polyethylene film used as the cap film and back film. The convex part of the cap film was cylindrical with a diameter of 10 mm and a height of 3.5 mm, and the cap film and back film were each 30 μm thick.

[0185] Comparative Example 2 For comparison, tissue paper ("Pure SIL Tissue" manufactured by TT Trading) was prepared as a packaging material.

[0186] Comparative Example 3 For comparison, tissue paper ("Kurumin no Himo" (a packaging material made from tissue paper in the form of a string) manufactured by Materials Preservation Equipment) was prepared.

[0187] The results are shown in Tables 1 to 5. Regarding the outgassing tests in the tables, the detected amount of acetic acid (μg / g) was "<0.6", the detected amount of formic acid (μg / g) was "<0.3", and the detected amount of Na + The detected amount of (sodium ion) (μg / g) is "<0.09", Ca 2+ The detected amount (μg / g) of "<0.3" indicates that the amount of each component was below the detection limit.

[0188] The abbreviations in the table have the following meanings: "LA-31(5)": Contains 5% of "ADEKA STAB LA-31" manufactured by ADEKA Corporation. "ADK STAB LA-31" to "Vonasorb (registered trademark)" manufactured by Orient Chemical Industry "Vonasorb (5)": Contains 5% of "Vonasorb (registered trademark)" manufactured by Orient Chemical Industry Co., Ltd. "PC-5857(5)": Contains 5% of "NUBIAN BLACK PC-5857" manufactured by Orient Chemical Industry Co., Ltd.

[0189] [Table 1]

[0190] [Table 2]

[0191] [Table 3]

[0192] [Table 4]

[0193] [Table 5]

[0194] As shown in Examples 1 to 13, it was confirmed that the generation of outgassing containing acid and alkaline components can be suppressed for packaging materials containing resin (A) at the outermost portion in the thickness direction of the packaging material, whereas in the comparative examples, it was confirmed that outgassing containing both acid and alkaline components was generated. [Explanation of symbols]

[0195] 1 resin layer 2. Air 3. Resin fiber M1, M2, M3 outermost 10A, 10B, 20A, 20B, 30: Packaging material 11 First Skin Layer 12 Core Layer 13 Second Skin Layer 21 Cap Film 22, 23 Back film

Claims

1. A packaging material for packaging an item, A packaging material comprising a resin (A) containing an alicyclic structure-containing polymer at the outermost portion in the thickness direction of the packaging material.

2. The packaging material according to claim 1 , wherein the resin (A) contains a crystalline alicyclic structure-containing polymer.

3. The packaging material according to claim 1 , which comprises a resin layer containing the resin (A).

4. the packaging material has a multi-layer film including a first skin layer, a core layer, and a second skin layer; The packaging material according to claim 3 , wherein the first skin layer and the second skin layer are resin layers containing the resin (A).

5. The packaging material of claim 4 , wherein the core layer comprises an ultraviolet absorber or a colorant.

6. The packaging material is a bubble wrap sheet having a cap film and a back film, The packaging material according to claim 3 , wherein the cap film and the back film each have a resin layer containing the resin (A).

7. the packaging material is a nonwoven fabric made of resin fibers, The packaging material according to claim 1 , wherein the resin fibers contain the resin (A).

8. The packaging material according to claim 1 , wherein the packaging material is a packaging material for packaging artwork.

9. 2. The packaging material according to claim 1, wherein the weight ratio of the alicyclic structure-containing polymer contained in the resin (A) is 70% by weight or more.

10. 2. The packaging material according to claim 1, wherein the amount of at least one of acetic acid, formic acid, sodium ions, and calcium ions detected from the resin (A) is 1 μg / g or less.

11. A method for preserving an article, comprising packaging an article using a packaging material and preserving the resulting package, A method for preserving an article, wherein the packaging material is the packaging material according to any one of claims 1 to 10.

12. The method for preserving an article according to claim 11, wherein the article is a work of art.

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