Resin film, packaging bag and package

Abstract

To provide a resin film that, even if exposed to low temperature in forming a packaging bag for packaging an article, can store and transport a packaged article stably, a packaging bag formed by using such a resin film and a package having an article packaged with such a packaging bag.SOLUTION: A film 2, 3 (resin film in the present invention), used for forming a packaging bag, consists of a laminate comprising a moisture-absorbing layer 11, a coat layer 12 (inner coat layer) laid on the moisture-absorbing layer 11 on a side where an article is packaged when a packaging bag is formed, and a coat layer 13 (outer coat layer) laid on the moisture-absorbing layer 11 on a side opposite to the side where an article is packaged when the packaging bag is formed. When bend processing is performed on the film 2, 3 under a condition of a temperature of -20°C and a cycle number of bending of 500 by a Gelbo Flex tester conforming to ASTM F392, it is satisfied that the number of pinholes found on the film 2, 3 is less than 30.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a resin film used to form a packaging bag for packaging an article, a packaging bag for packaging an article, and a package in which an article is packaged. [Background technology]

[0002] Conventionally, when packaging items such as medicines, cosmetics, food, chemicals, electronic components, electronic materials, and metal materials in a packaging bag, a package in which the item is packaged in the packaging bag has been formed by enclosing a small bag containing a moisture absorbent (desiccant) together with the item in the packaging bag in order to reduce the impact of the item absorbing moisture that becomes mixed into the gas in the packaging bag.

[0003] However, when packaging a sachet containing a moisture absorbent together with an article in a packaging bag in this way, a step of inserting the sachet containing the moisture absorbent into the packaging bag is required, and this step is generally performed manually, which requires time and effort, and furthermore, there is a problem that it is costly. In addition, since the sealing step is performed manually as described above, there is a problem that if the sachet is forgotten to be inserted into the packaging bag, or if the desiccant adheres to the article during this insertion, it adversely affects the properties of the article.

[0004] Depending on the type of item to be packaged in the packaging bag, the item may be packaged in a small bag, and the small bag containing the part and the moisture absorbent may then be packaged in a packaging bag. Naturally, this case also has the same problems as those described above.

[0005] In order to solve this problem, i.e., to eliminate the need to enclose the article and the moisture absorbent in a packaging bag, it has been proposed in recent years to use a resin film that constitutes the packaging bag in which the article is packaged, the resin film having a moisture absorbent layer that contains a moisture absorbent and a resin material that retains the moisture absorbent (see, for example, Patent Document 1).

[0006] In addition, such packaging bags are expected to be stored and transported in refrigeration or freezing depending on the type and characteristics of the packaged goods. Therefore, the packaging bags are required to be able to maintain their functionality even when exposed to low temperatures, that is, to be stable at low temperatures. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2010-116435 A Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a resin film that, when used to form a packaging bag for packaging an article, allows the packaged article to be stably stored and transported even when exposed to low temperatures, a packaging bag formed using such a resin film, and a package including an article packaged in such a packaging bag. [Means for solving the problem]

[0009] Such an object can be achieved by the present invention described in the following (1) to (11). (1) A resin film used to form a packaging bag for packaging an article, A moisture absorbing layer formed of a first resin composition containing a moisture absorbing agent and a first resin material for holding the moisture absorbing agent; an inner coating layer that is laminated on the side of the moisture absorbing layer that packages the article when the packaging bag is formed and is made of a second resin composition; an outer coating layer formed of a third resin composition and laminated on the moisture absorbing layer on the opposite side to the side on which the article is packaged when the packaging bag is formed; A resin film characterized in that, when the resin film is subjected to a flexing treatment under conditions of a temperature of -20°C and 500 flexing cycles using a Gelbo flex tester conforming to ASTM F392, the number of pinholes observed in the resin film is less than 30.

[0010] (2) The second resin composition and the third resin composition contain a second resin material and a third resin material as main materials, respectively; The resin film according to (1) above, wherein the second resin material and the third resin material are each a polyolefin resin other than polypropylene.

[0011] (3) The resin film according to (1) or (2), wherein the third resin composition contains, as the third resin material, 20% by weight or more of polyethylene having a specific gravity of 0.93 or more.

[0012] (4) The melting point of the second resin composition is F I [° C.], and the melting point of the third resin composition is F O [℃], the relation between these differences is (F O -F I ) is 10°C or higher.

[0013] (5) The resin film according to any one of (1) to (4) above, wherein the first resin material is a polyolefin resin other than polypropylene.

[0014] (6) The resin film according to any one of (1) to (5) above, wherein the content of the moisture absorbent in the first resin composition is more than 1.0% by weight and not more than 30.0% by weight.

[0015] (7) The resin film according to any one of (1) to (6) above, wherein the inner coating layer and the outer coating layer each have an average thickness of 1 μm or more and 60 μm or less.

[0016] (8) The resin film according to any one of (1) to (7), wherein the article is an electronic material.

[0017] (9) The resin film according to any one of (1) to (8) above, which is substantially free of aluminum.

[0018] (10) A packaging bag formed into a bag shape using the resin film according to any one of (1) to (9) above.

[0019] (11) A package comprising the packaging bag according to (10) above and the article packaged in the packaging bag. Effect of the Invention

[0020] According to the resin film of the present invention, when the resin film is subjected to a bending treatment at a temperature of -20°C and 500 bending times using a Gelbo flex tester conforming to ASTM F392, the number of pinholes found in the resin film is less than 30. Therefore, when such a resin film is used to form a packaging bag for packaging an article, even if the packaging bag is exposed to a low temperature for the purpose of refrigerating or freezing the article and the packaging bag is bent during storage and transportation of the article in this state, it is possible to appropriately suppress or prevent the occurrence of cracks (breaks) or pinholes in the packaging bag due to the bending. Therefore, when a package in which an article is packaged using this packaging bag is formed, the package is stored in a refrigerator or freezer, so that the package is exposed to a low temperature and even if the package is bent during this time, the article can be stably stored and transported in the package. [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 is a plan view showing the packaging state of the packaging bag of the present invention. [Diagram 2] FIG. 2 is a perspective view showing the packaging bag of the present invention in an unpackaged state. [Diagram 3]FIG. 1 is a longitudinal sectional view showing an embodiment of a resin film (resin film of the present invention) constituting the packaging bag of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the resin film, packaging bag, and packaging body of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

[0023] Fig. 1 is a plan view showing the packaging bag of the present invention in a packaged state, Fig. 2 is a perspective view showing the packaging bag of the present invention in an unpackaged state, and Fig. 3 is a vertical cross-sectional view showing an embodiment of a resin film (resin film of the present invention) constituting the packaging bag of the present invention. Note that, for convenience of explanation, the upper side in Figs. 1 to 3 will be referred to as "upper" and the lower side as "lower".

[0024] <Packaging bag> The packaging bag 1 of the present invention shown in Figures 1 and 2 is used for packaging an article to be packaged in a sealed state in this packaging bag 1, and the package of the present invention includes the packaging bag 1 and an article packaged in a sealed state in this packaging bag 1. Hereinafter, the state in which an article has not yet been packaged in the packaging bag 1 will be referred to as the "unpackaged state" (see Figure 2), and the state in which an article has been packaged in the packaging bag 1 will be referred to as the "packaged state" (see Figure 1). Note that in Figure 1, the illustration of the packaged article in the packaging bag 1 in the packaged state is omitted.

[0025] By using the packaging bag 1 of the present invention to package an article, the article packaged in the package can be stably stored and transported even if the packaging bag 1 is exposed to low temperatures. That is, the films 2 and 3 (the resin films of the present invention) used to form the packaging bag 1 satisfy the following criteria: when the films 2 and 3 are subjected to a bending treatment at a temperature of -20°C and 500 bending cycles using a Gelbo flex tester in accordance with ASTM F392, the number of pinholes observed in the films 2 and 3 is less than 30.

[0026] Therefore, when the films 2 and 3 are used to form the packaging bag 1 for packaging an article, even if the packaging bag 1 is exposed to low temperatures for the purpose of refrigerating or freezing the article and furthermore, even if an opportunity arises for the packaging bag 1 to be bent during storage and transportation of the article in this state, it is possible to appropriately suppress or prevent the occurrence of cracks (breaks) or pinholes in the packaging bag 1 due to bending at low temperatures. Therefore, when a package in which an article is packaged using the packaging bag 1 is formed, the package is refrigerated or frozen to store the package, so that the article can be stably stored and transported in the package, even if the packaging bag 1 is exposed to low temperatures and furthermore, even if an opportunity arises for the packaging bag 1 to be bent at this time.

[0027] The article to be packaged in the packaging bag 1 may be any article that absorbs moisture contained in the air (atmosphere) and affects the properties of the article. Examples of such articles include medicines, cosmetics, food, drugs, electronic parts, electronic materials, and metal materials. Among these, electronic materials are preferably selected as articles to be packaged in the packaging bag 1. The electronic materials refer to raw materials used in the formation of electronic parts such as semiconductor devices, and examples of such materials include semiconductor encapsulation materials used in the formation of encapsulation parts of semiconductor devices. Electronic materials such as semiconductor encapsulation materials are particularly susceptible to the effects of moisture absorption, and are articles that are packaged, stored, and transported in a refrigerated or frozen state, i.e., at low temperatures. Therefore, packaging with the packaging bag 1 (the packaging bag 1 of the present invention) that can stably suppress or prevent the effects of moisture absorption on the packaged article even when the packaging bag 1 is exposed to low temperatures is preferably applied to packaging electronic materials.

[0028] The packaging bag 1 is used for packaging an article. In the present embodiment shown in Fig. 1 and Fig. 2, for example, the packaging bag 1 is a sealed bag formed into a bag shape by overlapping a first film 2 and a second film 3, and an opening 23 through which the article can be put in and taken out is sealed by fusing or the like by heat sealing (thermocompression bonding).

[0029] There are various methods for producing such a packaging bag 1, and there is no particular limitation thereto, but for example, by forming a tubular film by heat-sealing two or one side of two overlapping resin films or folding one resin film, it is possible to obtain a packaging bag 1 having openings 23 opening on two opposing sides in the vertical direction. In such a packaging bag 1, an article is stored through one of the two openings 23, and then the openings 23 are heat-sealed and sealed to produce a package in which an article is packaged in the packaging bag 1 in a packaged state.

[0030] When two resin films are overlapped to produce packaging bag 1, these two resin films constitute first film 2 and second film 3. When one resin film is folded to produce packaging bag 1, the folded one resin film constitutes first film 2 and second film 3. The resin film of the present invention is applied to the first film 2 and second film 3 that constitute this packaging bag 1.

[0031] As shown in FIG. 3, films 2 and 3 (resin films of the present invention) are composed of a laminate including a moisture-absorbing layer 11, a coating layer 12 laminated on the upper side of the moisture-absorbing layer 11, and a coating layer 13 laminated on the lower side of the moisture-absorbing layer 11. When producing the packaging bag 1 as described above, the packaging bag 1 is produced such that the coating layer 12 (inner coating layer) is located on the side of the packaging bag 1 that packages an article, i.e., on the inside of the packaging bag 1, and the coating layer 13 (outer coating layer) is located on the outside of the packaging bag 1.

[0032] <Resin film> As described above, these films 2 and 3 (resin films of the present invention) are composed of a laminate in which coating layer 13 (outer coating layer), moisture absorbing layer 11, and coating layer 12 (inner coating layer) are laminated in this order, and packaging bag 1 is formed with coating layer 12 on the inside and coating layer 13 on the outside.

[0033] In the present invention, the films 2 and 3 used are those which satisfy the condition that when the films 2 and 3 are subjected to a flexing treatment under the conditions of a temperature of -20°C and 500 flexing cycles using a Gelbo flex tester conforming to ASTM F392, the number of pinholes observed in the films 2 and 3 is less than 30.

[0034] In this way, when the films 2 and 3 are subjected to a bending treatment using a Gelbo flex tester, it is satisfied that the number of pinholes found in the films 2 and 3 is less than 30. Therefore, when the films 2 and 3 are used to form a packaging bag 1 for packaging an article, even if the packaging bag 1 is exposed to a low temperature for the purpose of refrigerating or freezing the article and furthermore, an opportunity arises for the packaging bag 1 to be bent during storage and transportation of the article in this low temperature state, it is possible to appropriately suppress or prevent the occurrence of cracks (breaks) or pinholes in the packaging bag 1 due to this bending. Therefore, when a package in which an article is packaged using the packaging bag 1 is formed, the package is refrigerated or frozen to store the package, and furthermore, even if an opportunity arises for the packaging bag 1 to be exposed to a low temperature and furthermore, at this time, the article can be stably stored and transported in the package.

[0035] Each layer constituting the films 2 and 3 will now be described. <Moisture absorption layer 11> The moisture absorbing layer 11 is disposed as an intermediate layer between the covering layer 12 and the covering layer 13. This moisture absorbing layer 11 has a function of absorbing (capturing) moisture present in the gas contained inside the packaging bag 1 with the moisture absorbent contained in the moisture absorbing layer 11 after the moisture has permeated through the covering layer 12. In addition, it functions as an intermediate layer between the films 2 and 3 so that the number of pinholes found in the films 2 and 3 that have been subjected to the bending treatment is set to be less than the upper limit value.

[0036] This moisture absorbing layer 11 is made of a first resin composition, which contains a moisture absorbent and a first resin material for retaining the moisture absorbent in order to impart the above-mentioned functions to the moisture absorbing layer 11.

[0037] The first resin material is not particularly limited as long as it has the ability to retain the moisture absorbent, but examples thereof include thermoplastic resins such as polyolefin resins, cyclic polyolefin resins, polyester resins, polyurethane resins, silicone resins, polyamide resins, polyimide resins, polyvinyl chloride resins, and polycarbonate resins. One or more of these may be used in combination, but among them, polyolefin resins other than polypropylene are preferable. These resin materials are preferably selected as the first resin material because they have particularly excellent retention properties. In addition, since they have excellent water vapor barrier properties, they can suppress the movement of moisture in the thickness direction of the moisture absorption layer 11, and as a result, they can stably absorb water vapor (moisture) mixed in the gas contained inside the packaging bag 1 for a long period of time. Furthermore, by using these resin materials, it is relatively easy to satisfy the requirement that the number of pinholes observed in the films 2 and 3 when the bending treatment is performed on the films 2 and 3 is less than 30. Therefore, when the films 2 and 3 are used to form the packaging bag 1 for packaging an article, even if the packaging bag 1 is exposed to low temperatures for the purpose of refrigerating or freezing the article, and further, even if the packaging bag 1 is bent during storage and transportation of the article in this low-temperature condition, the occurrence of cracks (breaks) or pinholes in the packaging bag 1 due to this bending can be appropriately suppressed or prevented. In other words, it can be said that these resin materials have excellent refrigerated and frozen storage properties. Therefore, they are suitably selected when storing electronic materials (particularly semiconductor encapsulation materials) as articles, etc.

[0038] Examples of polyolefin resins other than polypropylene include homopolymers of α-olefins such as ethylene, 1-butene, isobutene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-icosene, copolymers of at least two types of α-olefins, and copolymers of α-olefins and other monomers. These polyolefin resins may be used alone or as a mixture of two or more of them.

[0039] Here, the other monomer is one that is copolymerizable with the α-olefin, and examples thereof include unsaturated carboxylic acids such as acrylic acid and methacrylic acid, unsaturated carboxylic acid esters such as acrylic acid esters and methacrylic acid esters, polybasic unsaturated carboxylic acids such as maleic acid, acid anhydrides of polybasic unsaturated carboxylic acids, conjugated dienes such as 1,3-butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, and dicyclopentadiene, and non-conjugated dienes such as dicyclopentadiene, 1,4-hexadiene, 1,9-decadiene, cyclooctadiene, norbornadiene, methylenenorbornene, ethylidenenorbornene, and 7-methyl-1,6-octadiene.

[0040] Specific examples of such polyolefin resins other than polypropylene include polyethylene resins such as very low density polyethylene (VLDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE), ethylene-α-olefin copolymers, ethylene-vinyl alcohol copolymers (EVOH), ethylene-vinyl acetate copolymers (EVA), ethylene-acrylic acid copolymers (EAA), ethylene-methyl methacrylate copolymers (EMMA), ethylene-ethyl acrylate copolymers (EEA), ethylene-styrene copolymers, and ethylene-maleic acid copolymers. In addition, acid-modified polyolefin resins obtained by modifying these polyolefin resins with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid can be mentioned.

[0041] In addition, the moisture absorbent (desiccant) may be either an inorganic or organic moisture absorbent as long as it is capable of absorbing (capturing) moisture. Examples of inorganic moisture absorbents include calcium chloride, calcium oxide, magnesium oxide, magnesium sulfate, calcium carbonate, potassium aluminum sulfate (alum), silicon oxide (silica gel) and zeolite. Examples of organic moisture absorbents include cellulose-based moisture absorbents, polyacrylate-based moisture absorbents, polyacrylic acid-based moisture absorbents, polyvinyl alcohol-based moisture absorbents, polyacrylamide-based moisture absorbents, polyoxyethylene-based moisture absorbents, etc., and one or a combination of two or more of these may be used.

[0042] The inorganic absorbent may be in the form of either a hydrate or anhydrous form of the above-mentioned substances, but from the viewpoint of absorbing a larger amount of moisture, anhydrous forms or hydrates with a smaller hydration number are preferably used.

[0043] The content of the moisture absorbent in the first resin composition is preferably more than 1.0% by weight and not more than 30.0% by weight, and more preferably more than 5.0% by weight and not more than 25.0% by weight. This allows the moisture absorption amount of the moisture absorbent layer 11 to be easily set within the range shown below, and the moisture that has permeated the coating layer 12 can be reliably absorbed (captured) by the moisture absorbent contained in the moisture absorbent layer 11. In addition, by setting the content of the moisture absorbent to be not more than the upper limit, the moisture absorbent layer 11 can be set to a more uniform thickness, and further, the tension of the moisture absorbent layer 11 can be appropriately suppressed or prevented from unintentionally decreasing. Therefore, the number of pinholes observed in the films 2 and 3 that have been subjected to the bending treatment can be relatively easily set to be less than the upper limit.

[0044] Furthermore, the moisture absorption amount of the moisture absorption layer 11 is preferably 0.01 g / g or more and 0.5 g / g or less, and more preferably 0.1 g / g or more and 0.5 g / g or less. By setting the moisture absorption amount of the moisture absorption layer 11 within the above range, the moisture absorbent contained in the moisture absorption layer 11 can reliably absorb (capture) the moisture that has permeated the coating layer 12.

[0045] The moisture absorption amount of the moisture absorption layer 11 can be obtained by cutting the films 2 and 3 immediately after production to a size of 10 cm x 10 cm, measuring the weight of the cut-out films 2 and 3, storing the films 2 and 3 under conditions of 23°C and 50% humidity, measuring the weight of the films 2 and 3 after 24 hours, and calculating the change in weight from the original weight of the films 2 and 3.

[0046] Furthermore, the average thickness of the moisture absorbing layer 11 is preferably set to 20 μm or more and 150 μm or less, more preferably 30 μm or more and 100 μm or less. This allows the amount of moisture absorbed by the moisture absorbing layer 11 to be easily set within the above range, and the moisture that has permeated the coating layer 12 can be reliably absorbed (captured) by the moisture absorbent contained in the moisture absorbing layer 11. Also, the number of pinholes found in the films 2 and 3 that have been subjected to the bending treatment can be relatively easily set to less than the upper limit.

[0047] <Coating layer 13> The covering layer 13 is laminated on the other surface side (lower surface side) of the moisture absorbent layer 11, and is a layer (outer covering layer) located on the opposite side of the packaging bag 1 from the side where the article is packaged, i.e., on the outside of the packaging bag 1. This covering layer 13 (outer covering layer) is located outside the moisture absorbent layer 11 as an intermediate layer in the packaging bag 1, and thus functions as a barrier layer that suppresses or prevents the moisture absorbent layers 11 of adjacent packages from contacting each other or from touching the moisture absorbent layer 11 with a human finger during storage and transportation of the packages. In addition, it functions as the outermost layer of the films 2 and 3 so that the number of pinholes found in the films 2 and 3 that have been subjected to the bending treatment is set to be less than the upper limit value.

[0048] The covering layer 13 is made of a third resin composition containing a third resin material as a main material. The third resin material is not particularly limited as long as it can be formed by covering (laminating) the covering layer 13 on the moisture absorbing layer 11. For example, the same materials as those listed as the first resin material can be used, but among them, polyolefin resins other than polypropylene are preferable. By using this resin material, it is relatively easy to satisfy that the number of pinholes observed in the films 2 and 3 when the bending treatment is performed on the films 2 and 3 is less than 30. Therefore, when the films 2 and 3 are used to form a packaging bag 1 for packaging an article, even if the packaging bag 1 is exposed to a low temperature for the purpose of refrigerating or freezing the article, and further, the packaging bag 1 is bent during storage and transportation of the article in this low temperature state, the occurrence of cracks (cracks) or pinholes in the packaging bag 1 due to the bending can be appropriately suppressed or prevented. When the third resin material is a polyolefin resin other than polypropylene, the third resin composition preferably contains polyethylene having a specific gravity of less than 0.93 as the third resin material or as the other resin material, which allows the effect obtained by using a polyolefin resin other than polypropylene as the third resin material to be more significantly exhibited.

[0049] Moreover, since the covering layer 13 constitutes the outermost layer located on the outside of the packaging bag 1, it is preferable that the covering layer 13 has a scratch resistance that prevents the covering layer 13 from being scratched when adjacent packages come into contact with each other or when the package is touched by a human finger during storage and transportation of the packages. From this viewpoint, when the third resin material is a polyolefin-based resin other than polypropylene, it is particularly preferable that the polyolefin-based resin is polyethylene having a specific gravity of 0.93 or more. This can reliably impart excellent scratch resistance to the covering layer 13.

[0050] Furthermore, in this case, the content of polyethylene having a specific gravity of 0.93 or more in the third resin composition is preferably 20% by weight or more, and more preferably 50% by weight or more and 100% by weight or less. By setting the content of polyethylene having a specific gravity of 0.93 or more in the third resin composition within the above range, excellent scratch resistance can be more reliably imparted to the coating layer 13.

[0051] Here, the scratch resistance of the coating layer 13 can be evaluated by the haze value when an abrasion test (scratch test) is performed on the coating layer 13. Specifically, an abrasion test according to JIS K 7204:1999 is performed on the coating layer 13 (outer coating layer) side of the films 2 and 3, and the haze values ​​of the films 2 and 3 before the abrasion test and after the abrasion test are measured using a haze meter according to JIS K 7105. The increase (ΔH) in the haze value of the films 2 and 3 before and after the abrasion test, which is calculated from these haze values, is preferably 0.05% or less, more preferably 0.00% or more and 0.03% or less. By setting this increase (ΔH) to the upper limit or less, it can be said that the coating layer 13 is provided with excellent scratch resistance.

[0052] The average thickness of the coating layer 13 is preferably set to 1 μm or more and 60 μm or less, more preferably 2 μm or more and 20 μm or less. This allows the average thickness of the coating layer 13 to be set within an appropriate range, so that the coating layer 13 can be more reliably provided with the above-mentioned function of the coating layer 13. Also, the number of pinholes found in the films 2 and 3 that have been subjected to the bending treatment can be relatively easily set to less than the upper limit.

[0053] <Coating layer 12> The covering layer 12 is laminated on one surface (upper surface) of the moisture absorbent layer 11, and is a layer (inner covering layer) located on the side of the packaging bag 1 where an article is packaged, i.e., on the inside of the packaging bag 1. This covering layer 12 (inner covering layer) allows water vapor (moisture) mixed in the gas contained inside the packaging bag 1 to pass through to the moisture absorbent layer 11 side, and also functions as a barrier layer that prevents the moisture absorbent layer 11 (moisture absorbent) from coming into contact with the article packaged inside the packaging bag 1. In addition, it functions as the innermost layer of the films 2 and 3 so that the number of pinholes found in the films 2 and 3 that have been subjected to the bending treatment is set to be less than the upper limit value.

[0054] The covering layer 12 is made of a second resin composition containing a second resin material as a main material. The second resin material is not particularly limited as long as it can be formed by covering (laminating) the covering layer 12 on the moisture absorbing layer 11. For example, the same materials as those listed as the first resin material can be used, but among them, polyolefin resins other than polypropylene are preferable. By using these resin materials, it is relatively easy to satisfy that the number of pinholes observed in the films 2 and 3 when the bending treatment is performed on the films 2 and 3 is less than 30. Therefore, when the films 2 and 3 are used to form a packaging bag 1 for packaging an article, even if the packaging bag 1 is exposed to a low temperature for the purpose of refrigerating or freezing the article, and further, the packaging bag 1 is bent during storage and transportation of the article in this low temperature state, the occurrence of cracks (cracks) and pinholes in the packaging bag 1 due to the bending can be appropriately suppressed or prevented.

[0055] Furthermore, as mentioned above, in order to impart scratch resistance to the coating layer 13, when the third resin material in the coating layer 13 contains polyethylene having a specific gravity of 0.93 or more as a polyolefin-based resin other than polypropylene, it is preferable that the second resin material in the coating layer 12 contains ethylene-vinyl acetate copolymer (EVA) as a polyolefin-based resin other than polypropylene.

[0056] Furthermore, in this case, the content of the ethylene-vinyl acetate copolymer in the second resin composition is preferably 20% by weight or more, and more preferably 50% by weight or more and 100% by weight or less.

[0057] By setting the content of the ethylene-vinyl acetate copolymer in the second resin composition within the above range, the melting point of the second resin composition can be set to F I [°C], and the melting point of the third resin composition is F O [℃], the relation between these differences is (F O -F I ) is set to 10°C or greater.

[0058] In this embodiment, as described above, the opening 23 is fused by heat sealing (thermocompression bonding) to seal the packaging bag 1. In this case, it is required that the films 2 and 3 have fusion properties (heat sealability) at the opening 23. However, if the above-mentioned relational formula (F O -F I ) is set to 10° C. or more, excellent fusion properties can be imparted to the films 2 and 3. Therefore, in the covering layer 12, as described above, the second resin material preferably contains an ethylene-vinyl acetate copolymer as a polyolefin resin other than polypropylene.

[0059] In addition, when the films 2 and 3 are to be fusible with each other, (F O -F I )≧10°C, the combination of the second resin material and the third resin material is not limited to the combination of polyethylene having a specific gravity of 0.93 or more and ethylene-vinyl acetate copolymer (EVA) as described above, but may be, for example, a combination of polyethylene having a specific gravity of less than 0.93 and EVA (F O -F I =25℃).

[0060] The average thickness of the coating layer 12 is preferably set to 1 μm or more and 60 μm or less, more preferably 2 μm or more and 20 μm or less. This allows the average thickness of the coating layer 12 to be set within an appropriate range, so that the coating layer 12 can be more reliably provided with the above-mentioned function of the coating layer 12. Also, the number of pinholes found in the films 2 and 3 that have been subjected to the bending treatment can be relatively easily set to less than the upper limit.

[0061] Here, when the films 2 and 3 are subjected to a bending treatment under conditions of a temperature of -20°C and 500 bending cycles using a Gelbo flex tester conforming to ASTM F392, the number of pinholes found in the films 2 and 3 may be less than 30, preferably 15 or less, and more preferably 0 to 10. As a result, when the films 2 and 3 are used to form a packaging bag 1 for packaging an article, even if the packaging bag 1 is exposed to a low temperature for the purpose of refrigerating or freezing the article and furthermore the packaging bag 1 is bent during storage and transportation of the article in this state, it is possible to more appropriately suppress or prevent the occurrence of cracks (breaks) or pinholes in the packaging bag 1 due to this bending. Therefore, the article can be more stably stored and transported in a package in which the article is packaged using the packaging bag 1.

[0062] In the present invention, the bending treatment using a Gelbo Flex Tester is performed by using a Gelbo Flex Tester (e.g., "BE-1006" manufactured by Tester Sangyo Co., Ltd.) conforming to ASTM F392, and wrapping and fixing the films 2 and 3 as test pieces with a width of 15.5 cm around two opposing disks with a diameter of 8.8 cm provided in the Gelbo Flex Tester, with the width of the films 2 and 3 being the distance between the two disks. Thereafter, the test piece thus fixed into a cylindrical shape is subjected to a bending treatment of twisting 500 times under a temperature condition of -20°C. The number of pinholes (through holes) generated in the test piece removed from the two disks is visually counted to determine the number of pinholes observed in the films 2 and 3 due to the bending treatment.

[0063] In this embodiment, the films 2 and 3 are composed of a laminate in which the coating layer 12, the moisture-absorbing layer 11, and the coating layer 13 are laminated in this order, but are not limited to this configuration, and may be composed of a laminate including an intermediate layer such as an adhesive layer disposed at least one between the coating layer 12 and the moisture-absorbing layer 11 and between the coating layer 13 and the moisture-absorbing layer 11. When an adhesive layer is provided between the coating layer 12 and the moisture-absorbing layer 11, an adhesive layer having a water vapor permeability similar to that of the coating layer 12 is selected.

[0064] The films 2 and 3 made of the laminate as described above are composed of materials that do not substantially contain conductive materials such as aluminum, which reliably prevents conductive materials from adhering to the article packed in the packaging bag 1 inside the packaging body and thus preventing the properties of the article from being adversely affected.

[0065] Moreover, the average thickness of the films 2 and 3, i.e., the total thickness of the laminate, is preferably 50 μm to 200 μm, more preferably 55 μm to 180 μm. This ensures that each layer of the films 2 and 3 has a thickness suitable for imparting the function of each layer. Therefore, moisture mixed in the gas in the packaging bag 1 can be stably absorbed for a long period of time.

[0066] In the present invention, various items are packaged in the packaging bag 1, and the number of items may be either one or multiple, but the total weight of the items is preferably about 30 g / bag or more and 15,000 g / bag or less, and more preferably about 50 g / bag or more and 10,000 g / bag or less.

[0067] Although the resin film, packaging bag, and package of the present invention have been described above with reference to the illustrated embodiments, the present invention is not limited thereto, and each part constituting the resin film, packaging bag, and package can be replaced with any other part capable of exerting the same function. In addition, any other component can be added.

[0068] Furthermore, the packaging bag is not limited to the sealed bag described in the above embodiment, but may be, for example, a bag in the form of a gusset bag, or the like, and may also be in a form in which items are filled into a tray, cup, etc., and then packaged in a packaging bag. EXAMPLES

[0069] The present invention will be described in detail below based on examples, but the present invention is not limited to these.

[0070] 1. Preparation of raw materials The following raw materials were prepared for producing the resin film.

[0071] (Resin material) High density polyethylene (HDPE, Prime Polymer, "3300F", specific gravity: 0.949, melting point: 130℃) Linear low-density polyethylene (LLDPE, Ube Maruzen Polyethylene Co., Ltd., "1520F", specific gravity: 0.913, melting point: 99 / 114℃) Low-density polyethylene (LDPE, Ube Maruzen Polyethylene Co., Ltd., "F222NH", specific gravity: 0.922, melting point: 110°C) Ethylene vinyl acetate copolymer (EVA, Mitsui Dow Polychemicals, "V5714C", melting point: 89℃) Polypropylene (PP, manufactured by Sumitomo Chemical Co., Ltd., "FL331G5 melting point: 160°C")

[0072] (Moisture absorbent) - Pellet-shaped moisture absorbent containing moisture-absorbing filler (manufactured by Sasaki Chemical Co., Ltd., "S-KID")

[0073] 2. Manufacturing of resin films <Example 1> First, a first resin composition was prepared consisting of 80 parts by weight of low-density polyethylene (LDPE) and 20 parts by weight of a moisture absorbent (S-KID). A second resin composition was prepared consisting of ethylene-vinyl acetate copolymer (EVA). A third resin composition was prepared consisting of high-density polyethylene (HDPE).

[0074] Next, the second resin composition was formed into a film by an extrusion T-die method to obtain a covering layer 12 having an average thickness of 30 μm.

[0075] Next, the coating layer 12 was subjected to the extrusion T-die method using the first resin composition and the third resin composition in sequence to form a film from each of them, thereby forming a laminate in which a moisture absorption layer 11 having an average thickness of 30 μm and a coating layer 13 having an average thickness of 30 μm were laminated in this order on the coating layer 12, thereby obtaining a resin film.

[0076] Next, the obtained resin film was folded and then one side opposite to the one side formed by this folding was fused by heat sealing (thermocompression bonding) to produce a packaging bag 1 having an inner dimension of 100×100 mm.

[0077] Then, ten polypropylene pellets having a diameter of 10 mm and a height of 30 mm were placed in this packaging bag 1 as articles, and the two openings 23 on each of the two opposing sides were sealed with heat sealing to obtain the package of Example 1.

[0078] <Examples 2 to 6, Comparative Examples 1 and 2> Packages of Examples 2 to 6 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that at least one of the second resin composition and the third resin composition was changed to one shown in Table 1.

[0079] 3. Evaluation The packages of the Examples and Comparative Examples were evaluated as follows.

[0080] 3-1. Freezer storage stability of packaging bags (Gelbo flex tester test) For each of the resin films of the Examples and Comparative Examples, a Gelbo Flex Tester (manufactured by Tester Sangyo Co., Ltd., "BE-1006") conforming to ASTM F392 was used to wrap and fix a 15.5 cm wide resin film as a test piece around two opposing disks with a diameter of 8.8 cm provided in the Gelbo Flex Tester, with the width of the resin film being the distance between the two disks. Thereafter, the test piece thus fixed into a cylindrical shape was subjected to a bending treatment of twisting 500 times under a temperature condition of -20°C, thereby carrying out a Gelbo Flex Tester test. The number of pinholes (through holes) generated in the test piece removed from the two disks was visually counted and evaluated according to the following criteria.

[0081] [Evaluation Criteria] ⊚: The number of pinholes in the test piece is less than 15. ◯: The number of pinholes in the test piece is 15 or more and less than 30. ×: The number of pinholes in the test piece is 30 or more.

[0082] 3-2. Freezing stability during transportation of packaged products Five of the packages of each Example and Comparative Example were stacked in the thickness direction and loaded onto the bed of a truck. After that, the packages were transported by truck under a temperature condition of -20°C. The presence or absence of cracks in the packaging bag 1 of each package was then visually observed and evaluated according to the following criteria.

[0083] [Evaluation Criteria] ⊚: No scratches or cracks were found on the packaging bag 1. ◯: slight scratches are observed on the packaging bag 1, but no cracks are observed. ×: Obvious cracks are observed in the packaging bag 1.

[0084] 3-3. Moisture absorption properties of the moisture absorption layer of the packaging bag For the resin films of each Example and Comparative Example, the resin film immediately after production was cut into 10 cm x 10 cm pieces, the weight of the cut resin film was measured, and the resin film was then stored under conditions of 23°C and 50% humidity. The weight of the resin film after 24 hours was measured, and the amount of change from the original weight was calculated to determine the moisture absorption amount (g / g) of the moisture absorption layer 11, and evaluated according to the following criteria. An electronic balance (manufactured by AS ONE Corporation, "EX124G") was used for the weight measurement.

[0085] [Evaluation Criteria] ◯: The moisture absorption amount of the moisture absorptive layer 11 is 0.02 g / g or more. ×: The moisture absorption amount of the moisture absorptive layer 11 is less than 0.02 g / g.

[0086] 3-4. Weldability of packaging bags For each of the resin films in each of the Examples and Comparative Examples, the resin film was folded and then the side opposite to the side formed by this folding was heat sealed at 130 to 180°C with a pressure of 0.5 MPa to produce a packaging bag 1 with inner dimensions of 100 mm x 100 mm. The presence or absence of an unfused area on the fused side was visually observed and evaluated according to the following criteria.

[0087] [Evaluation Criteria] ⊚: No unfused area was observed on one of the fused sides. ○: Some air bubbles were found on one of the fused sides, but It cannot be said that there are any unfused areas. ×: A clear unfused area was observed on one fused side. The evaluation results thus obtained are shown in Table 1.

[0088] [Table 1]

[0089] As shown in Table 1, in each Example, when the resin film was subjected to a bending treatment at a temperature of -20°C using a Gelbo flex tester conforming to ASTM F392, the number of pinholes observed in the resin film was less than 30, and as a result, even if the packaged body was transported by truck under refrigerated or frozen storage conditions, the occurrence of cracks in the packaging bag could be appropriately suppressed or prevented. In other words, according to the packaging bag 1 formed using the resin film of each Example, the packaged body containing the packaged body could be stably stored and transported even if it was exposed to low temperatures.

[0090] In contrast, in each of the comparative examples, when the resin film was subjected to a bending treatment at a temperature of -20°C using a Gelbo flex tester in accordance with ASTM F392, the number of pinholes observed in the resin film did not satisfy the requirement of less than 30, and as a result, cracks were generated in the packaging bag when the package was transported by truck under refrigerated or frozen storage conditions. In other words, in the packaging bag 1 formed using the resin film of each comparative example, the package containing an article could not be stably stored or transported under conditions where the package was exposed to low temperatures.

[0091] 1 packaging bag 2. First Film 3. Second Film 11 Moisture absorption layer 12 Covering layer 13 Covering layer 23 Aperture

Claims

1. A resin film used to form a packaging bag for packaging an article, a moisture absorbing layer formed of a first resin composition containing a moisture absorbing agent and a first resin material for holding the moisture absorbing agent; an inner coating layer that is laminated on the side of the moisture absorbing layer that packages the article when the packaging bag is formed and is made of a second resin composition; an outer coating layer formed of a third resin composition and laminated on the moisture absorbing layer on the opposite side to the side on which the article is packaged when the packaging bag is formed; A resin film characterized in that, when the resin film is subjected to a flexing treatment under conditions of a temperature of -20°C and 500 flexing cycles using a Gelbo flex tester conforming to ASTM F392, the number of pinholes observed in the resin film is less than 30.

2. the second resin composition and the third resin composition contain a second resin material and a third resin material as main materials, respectively; The resin film according to claim 1 , wherein the second resin material and the third resin material are each a polyolefin resin other than polypropylene.

3. The resin film according to claim 2 , wherein the third resin composition contains 20% by weight or more of polyethylene having a specific gravity of 0.93 or more as the third resin material.

4. The melting point of the second resin composition is F Ｉ [° C.], and the melting point of the third resin composition is F Ｏ [℃], the relational expression of these differences is (F Ｏ -F Ｉ 3. The resin film according to claim 2, wherein the temperature is 10° C. or higher.

5. The resin film according to claim 1 , wherein the first resin material is a polyolefin resin other than polypropylene.

6. The resin film according to claim 3 , wherein the content of the moisture absorbent in the first resin composition is more than 1.0% by weight and not more than 30.0% by weight.

7. The resin film according to claim 1 , wherein the inner coating layer and the outer coating layer each have an average thickness of 1 μm or more and 60 μm or less.

8. The resin film according to claim 1 , wherein the article is an electronic material.

9. The resin film according to claim 1 , which is substantially free of aluminum.

10. A packaging bag formed into a bag shape using the resin film according to claim 1.

11. A package comprising the packaging bag according to claim 10 and the article packaged in the packaging bag.

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