TW202007531A - Multilayer film and package - Google Patents

Abstract

Provided are a multilayer film (1) that includes at least a sealant layer (2) provided so as to be a surface layer of the multilayer film and having at least a linear low-density polyethylene, in which a density of the linear low-density polyethylene is 0.93 or more, and a package that includes the multilayer film (1) and a sterilizing paper, in which at least a part of the sealant layer (2) of the multilayer film (1) is heat-sealed onto the sterilizing paper.

Description

Multilayer film and packaging

The invention relates to a multilayer film and a packaging body. This application claims based on Japanese Patent Application No. 2018-137395 filed on July 23, 2018, Japanese Patent Application No. 2019-40869 filed on March 6, 2019 in Japan, and Japanese Patent Application No. 2019-40869 applied on July 2, 2019 Priority No. 2019-123818, and its contents are cited here.

In recent years, a deep-drawn package (hereinafter, also referred to as "deep-drawn package") has been used as a medical package. In a deep-drawn package, a substrate made of a multi-layer film with a recess formed in the center, and a cover material made of polyethylene nonwoven fabric or sterilized paper (hereinafter, also referred to as "PE nonwoven fabric, etc.") are heated by heat Sealed and so on. In addition, gauze for business use, cotton swabs, medical equipment, etc. are housed in the recesses.

Conventionally, as a substrate for medical packaging, a multilayer film formed by laminating (laminating method) a polyester film or a nylon film and a heat-sealable resin film is generally widely used. On the other hand, as the cover material, from the viewpoint of gas permeability of the sterilization gas in the sterilization step, as described above, a polyethylene nonwoven fabric or sterilization paper is used.

However, depending on its usage, the medical packaging is required to be easy to open. In addition, as the cover material of the medical packaging body, polyethylene nonwoven fabric is selected from the viewpoint that hygiene is important. The polyethylene nonwoven fabric coated with an adhesive and imparting easy-opening properties is expensive, and the air permeability is also reduced. Therefore, the easy peelability function is given to the multilayer film side sealed with the polyethylene nonwoven fabric. In order to impart easy-openability to medical packages, as a multilayer film used as a substrate, it is known to provide a peelable resin layer (hereinafter, also referred to as "easy-peelable layer") on the sealing side with a PE-made nonwoven fabric or the like. ) Structure (Patent Literature 1). Further, there is known a co-extrusion for deep-drawing forming, which has a polyamide resin layer, a sealing layer that can be heat-sealed with polyethylene nonwoven fabric or sterilized paper at 135° C. or lower, and an easily peelable layer having interlayer peelability with the sealing layer. Multilayer film (Patent Document 2). [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2014-162162 [Patent Document 2] Japanese Patent Laid-Open No. 2014-19006

[Problems to be solved by the invention]

Multilayer films used as substrates for medical packaging require heat sealing with sterilization paper as a cover material, but when peeling the sterilization paper, if a part of the sterilization paper remains on the peeling surface of the substrate In other words, if so-called paper residues are generated, paper fibers may be attached to medical devices or the like contained in medical packaging and enter the body, the fibers may float, and the cleanliness may be reduced.

The present invention was completed in view of the above circumstances, and its object is to provide a multi-layer film and a packaging body that can be used as a substrate that can ensure an appropriate sealing strength when heat-sealing with sterilized paper and that does not cause paper residue on the peeling surface . [Means to solve the problem]

In order to achieve the above object, the present invention adopts the following structure. [1] A multilayer film having at least a sealant layer provided as a surface layer, The sealant layer contains at least linear low-density polyethylene, and the density of the linear low-density polyethylene is 0.93 or more. [2] The multilayer film of [1], wherein the sealant layer further comprises low density polyethylene, and the mass ratio of the linear low density polyethylene to the low density polyethylene is in the range of 50:50 to 99:1 . [3] The multilayer film according to [1] or [2], which includes a base material layer provided adjacent to the sealant layer and containing a polyethylene-based resin. [4] The multilayer film of [3], wherein the base material layer includes linear low-density polyethylene. [5] The multilayer film according to [3] or [4], wherein the thickness ratio of the sealant layer to the base material layer is in the range of 1:0.5 to 1:15. [6] The multilayer film according to any one of [1] to [5], wherein the low molecular weight volatile component of the linear low-density polyethylene contained in the sealant layer is 0.1 wt% or less. [7] The multilayer film according to any one of [1] to [6], wherein the molecular weight distribution (Mw/Mn) of the linear low-density polyethylene contained in the sealant layer is 7.0 or less, and, The number average molecular weight Mn of the linear low-density polyethylene is 20,000 or more. [8] The multilayer film according to any one of [1] to [7], which can be heat-sealed with sterilized paper in the range of 135 to 155°C. [9] A packaging body comprising the multilayer film of any one of [1] to [8] and sterilized paper, At least a part of the sealant layer of the multilayer film is heat-sealed on the surface of the sterilized paper. [10] The package according to [9], wherein the sealing strength of the multilayer film and the sterilized paper is 1.0 to 7.7 (N/15 mm). [Effect of invention]

As described above, the multilayer film of the present invention includes at least a sealant layer provided as a surface layer, the sealant layer includes at least a linear low-density polyethylene, and the density of the linear low-density polyethylene is 0.93 or more Therefore, the package formed by heat sealing the multi-layer film and the sterilization paper has the following excellent effects: it can ensure an appropriate sealing strength, and can prevent a part of the sterilization paper from remaining on the peeling surface of the substrate when the sterilization paper is peeled. That is, it is possible to suppress the generation of so-called paper residues, and it is possible to provide a packaging body having no problem in terms of hygiene.

Hereinafter, the multilayer film and the package to which one embodiment of the present invention is applied will be described in detail. In addition, in the drawings used in the following description, in order to facilitate understanding of the features, for convenience, there may be cases where the features are enlarged and displayed, but the dimensional ratios of the constituent elements and the like are not necessarily the same as the actual ones.

<Multilayer film> First, the structure of the multilayer film to which one embodiment of the present invention is applied will be described. FIG. 1 is a schematic cross-sectional view of a multilayer film 1 to which an embodiment of the present invention is applied. As shown in FIG. 1, the multilayer film 1 of the present embodiment is roughly configured to include a sealant layer 2 provided as a surface layer and a base material layer 3 provided adjacent to the sealant layer 2. Further, as shown in FIG. 2, the multilayer film 1 of the present embodiment may include a sealant layer 2 provided as a surface layer, a base material layer 3 provided adjacent to the sealant layer 2, and a laminate on the base material The structure of the other resin layers on the layer 3 is outlined. The multilayer film 1 of the present embodiment can be used as a packaging body, especially a film for a substrate of a medical packaging body.

(Sealant layer) The sealant layer 2 is a resin layer provided to be joined to sterilized paper to be joined by heat sealing and to provide easy opening. The sealant layer 2 contains at least linear low-density polyethylene, and the density of the linear low-density polyethylene is 0.93 or more, preferably 0.93 or more and 0.98 or less, and more preferably 0.93 or more and 0.95 or less. If the density of the linear low-density polyethylene is equal to or greater than the lower limit of the above range, heat sealing with appropriate seal strength can be performed with the sterilized paper, and when the sterilized paper is peeled off, paper residue on the peeling surface can be suppressed . On the other hand, if it is below the upper limit of the above range, it is easy to heat seal with sterilized paper.

The resin that can be used for the sealant layer 2 is not particularly limited as long as it contains a linear low-density polyethylene (LLDPE) having the above-mentioned density, and it preferably contains a linear low-density metallocene catalyst Polyethylene (mLLDPE) resin. The linear low-density polyethylene (LLDPE) having the aforementioned density is preferably a resin with a low detection amount of low molecular weight volatile components by GC-MS. If there are few low molecular weight volatile components, no gas will be generated during molding, which can prevent equipment contamination. The detection amount of the low molecular weight volatile component is preferably 0.1 wt% or less, and more preferably 0.05 wt% or less. In addition, the linear low-density polyethylene (LLDPE) having the aforementioned density is preferably a resin having a low content of low molecular weight components in the molecular weight distribution (Mw/Mn) by GPC. If the content of the low-molecular-weight component is small, no foreign matter will adhere to the forming hot plate during forming, and equipment contamination can be prevented. For linear low-density polyethylene (LLDPE), based on the value of molecular weight distribution (Mw/Mn) based on GPC, it is preferably 7.0 or less, and more preferably 4.5 or less. In addition, the number average molecular weight Mn is preferably 20,000 or more, and more preferably 23,000 or more. In addition, in the linear low-density polyethylene (LLDPE), the melting point peak measured by DSC may be one, or may have two or more peaks, and the highest melting point peak temperature is preferably 120° C. or higher. More preferably, the resin having the highest melting point peak temperature of 120°C or higher and the lowest melting point peak not below 100°C is preferred. It is further preferred that the resin has the highest melting point peak temperature of 120°C or higher and the lowest melting point peak of 110°C or lower. As described above, the resin will not be melted by heating during molding, and equipment contamination can be prevented.

Moreover, the sealant layer 2 may contain low-density polyethylene.

When the sealant layer 2 further contains low-density polyethylene, the quality of the linear low-density polyethylene and the low-density polyethylene in the resin constituting the sealant layer 2 is preferably in the range of 50:50 to 99:1, more preferably It is in the range of 60:40 to 99:1, further preferably in the range of 80:20 to 99:1.

The content of the linear low-density polyethylene in all resins constituting the sealant layer 2 is preferably 30 to 100% by mass, and more preferably 50 to 100% by mass. When the sealant layer 2 further contains low-density polyethylene, the total content of the linear low-density polyethylene and the low-density polyethylene is preferably 30 to 100% by mass, and more preferably 50 to 100% by mass. If the content of the linear low-density polyethylene is within the above-mentioned preferred range, the heat seal strength is more stable, and when peeling off the sterilized paper, the paper residue on the sealant layer 2 is further suppressed.

From the viewpoint of improving low-temperature heat sealability, the sealant layer 2 may contain additives. Examples of the additives include terpene-based resins (for example, "Hirodine series" manufactured by YASUHARA CHEMICAL CO., LTD.) and the like.

The thickness of the sealant layer 2 is preferably 3 to 70 μm, and more preferably 5 to 45 μm. If the thickness is more than the lower limit of the preferred range, a higher seal strength can be obtained when heat-sealing with sterilized paper, and if it is less than the upper limit, the effect of easy opening can be further improved during opening improve.

(Substrate layer) The base material layer (also referred to as the core layer) 3 is a resin layer provided adjacent to the sealant layer 2 in order to impart flexibility to the multilayer film 1. The resin that can be used for the base material layer 3 is not particularly limited as long as it can impart the above-mentioned functions, and polyethylene-based resins and the like can be cited.

As the polyethylene-based resin, for example, the following resins may be used alone or in combination of two or more: low density polyethylene (LDPE) resin, linear low density polyethylene (LLDPE) resin, medium density polyethylene (MDPE) resin, Homopolymer of ethylene such as high density polyethylene (HDPE) resin; ethylene-vinyl acetate copolymer (EVA) resin, ethylene-methyl methacrylate copolymer (EMMA) resin, ethylene-ethyl acrylate copolymer (EEA ) Resin, ethylene-methyl acrylate copolymer (EMA) resin, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH) resin, ethylene-acrylic acid copolymer (EAA) resin, ethylene-methacrylic acid Copolymer (EMAA) resin and other vinyl copolymers; ionic polymer (ION) resin and so on. As the polyethylene resin, the aforementioned LLDPE is preferred. By using LLDPE as the resin contained in the base material layer 3, a more stable heat seal strength (synergistic effect with the resin containing the linear low-density polyethylene used in the sealant layer 2) can be obtained.

The base material layer 3 may be only one layer, or may be a plurality of more than two layers as shown in FIG. 2. For example, by setting the base material layer 3 to be composed of a plurality of layers of different materials, characteristics such as the hardness of the base material layer 3 can be adjusted. Examples of the base material layer having two or more layers include a base material layer having two layers of LDPE and LLDPE.

The thickness of the base material layer 3 is preferably 15 to 150 μm, and more preferably 30 to 100 μm. If the thickness is equal to or greater than the lower limit of the preferred range, the flexibility of the multilayer film 1 is improved, and if it is equal to or less than the upper limit, more stable seal strength can be obtained.

In the multilayer film 1 of the present embodiment, the comparison of the thicknesses of the sealant layer 2 and the base material layer 3 is preferably in the range of 1:0.5 to 1:15, more preferably in the range of 1:0.5 to 1:10, and still more preferably It is in the range of 1:2 to 1:10. If the ratio is above the lower limit value of the above-mentioned preferred range, the effect of preventing curling of the package can be obtained, and if it is below the upper limit value, a more stable seal strength can be obtained.

The multilayer film 1 of the present embodiment may include other resin layers in addition to the sealant layer 2 and the base material layer 3 as long as the effects of the present invention are not impaired. In the multilayer film 1 shown in FIG. 2, the adhesive resin layer 4 and the pinhole-resistant layer 5 are laminated on the base material layer 3 as other resin layers.

(Adhesive resin layer) The adhesive resin layer 4 is a resin layer provided to increase the interlayer strength of each resin layer constituting the multilayer film 1 other than the interlayer between the sealant layer 2 and the base material layer 3.

As the adhesive resin that can be applied to the adhesive resin layer 4, a known adhesive olefin-based resin, for example, an adhesive polypropylene-based resin, an adhesive polyethylene-based resin, or the like can be used. The adhesive resin layer 4 may contain an antioxidant in order to prevent its oxidation. As the antioxidant, known antioxidants such as hindered phenol-based antioxidants, phosphorus-based antioxidants, and thioether-based antioxidants can be used alone or in combination of two or more. In addition, from the viewpoint of improving adhesiveness and mechanical properties, the adhesive resin layer 4 may contain cellulose nanofibers.

The thickness of the adhesive resin layer 4 is not particularly limited as long as it can bond the layers with a desired adhesive strength, and is preferably 2 to 30 μm, and more preferably 5 to 25 μm.

(Pinhole-resistant layer) The pinhole-resistant layer 5 is a resin layer provided to impart pinhole resistance to the multilayer film 1. From the viewpoint of improving the pinhole resistance, the pinhole resistance layer 5 preferably contains a polyamide resin. Examples of the polyamide resin contained in the pinhole-resistant layer 5 include 4-nylon, 6-nylon, 7-nylon, 11-nylon, 12-nylon, 46-nylon, 66-nylon, 69-nylon, 610-nylon, 611-nylon, 612-nylon, 6T-nylon, 6I-nylon, copolymer of 6-nylon and 66-nylon (nylon 6/66), copolymer of 6-nylon and 610-nylon, 6- Copolymer of nylon and 611-nylon, copolymer of 6-nylon and 12-nylon (nylon 6/12), copolymer of 6-nylon and 612-nylon, copolymer of 6-nylon and 6T-nylon, 6- Copolymer of nylon and 6I-nylon, copolymer of 6-nylon and 66-nylon and 610-nylon, copolymer of 6-nylon and 66-nylon and 12-nylon (nylon 6/66/12), 6-nylon Copolymers with 66-nylon and 612-nylon, 66-nylon and 6T-nylon, 66-nylon and 6I-nylon, 6T-nylon and 6I-nylon, and 66-nylon and 6T -Copolymer of nylon and 6I-nylon, amorphous nylon, etc. Among them, from the viewpoint of heat resistance, mechanical strength, and easy availability, 6-nylon, 12-nylon, 66-nylon, nylon 6/66, nylon 6/12, nylon 6/66/12, etc. are more preferable. Preferably it is 6-nylon.

The total thickness of the pinhole-resistant layer 5 is not particularly limited, but it is preferably 10 to 90 μm, and more preferably 12 to 50 μm.

(additive) The multilayer film 1 of the present embodiment can add known lubricants and additives to the sealant layer 2 and the base material layer 3 as necessary in order to provide smoothness, prevent adhesion, and impart anti-fogging properties. For smoothness and prevention of adhesion, organic lubricants such as oleamide and erucamide, inorganic lubricants such as silica, zeolite, and calcium carbonate can be cited. In addition, in order to impart antifogging properties, known surfactants and the like can be appropriately used.

<Manufacturing method of multilayer film> Next, an example of the method for manufacturing the multilayer film 1 will be described. The manufacturing method of the above-mentioned multilayer film 1 is not particularly limited, and examples thereof include a co-extrusion T-die method such as a melt extruding resin or the like as a raw material using a plurality of extruders, a multi-manifold method, and an air-cooled type Or water-cooled co-extrusion expansion method and lamination method. Among them, from the viewpoint of excellent control of the thickness of each layer, particularly preferred is a method of forming a film by a co-extrusion T-die method.

As the lamination method, dry lamination method, extrusion lamination method, hot melt lamination method, wet lamination method, thermal ) Lamination method, etc. and combinations of these methods. In addition, it can also be laminated by coating.

<Package> Next, an example of a package using the multilayer film 1 described above will be described. The package of this embodiment includes the above-mentioned multilayer film and sterilized paper, and at least a part of the sealant layer of the multilayer film is heat-sealed on the surface of the sterilized paper.

As the sterilization paper that can be applied to the packaging body of the present embodiment, as long as it can be heat-sealed with the sealant layer and has air permeability and prevents the penetration of bacteria (has bacteriostatic properties), and can be sterilized, the paper is used as There are no special restrictions on the main constituent material. Examples of the sterilization paper include "Medica D (manufactured by Oji F-Tex Co., Ltd.)" and the like.

When the packaging body of the present embodiment is used as a medical packaging body, the sterilized paper preferably has small holes that can exhibit air permeability and bacteriostatic properties. Specifically, it is preferably composed of fibers in the range of 0.0001 to 20 dtex, and a sterilized paper having a basis weight of 10 to 300 g/m ² .

The package of the present embodiment can be used as a deep-drawn package by deep-drawing the substrate, filling it with contents such as gauze, and covering it with a cover material, and heat-sealing. In particular, when the above-mentioned multilayer film is used as a base material of a deep-drawn packaging body, and a sterilized paper is used as a cover material, a good deep-drawn packaging body can be obtained.

The packaging body of this embodiment can be produced by using a subsequent method such as heat sealing to subsequently use a multilayer film as a substrate and sterilized paper as a cover. Specifically, the package can be produced by heat sealing in a temperature range of preferably 135 to 155°C of the multilayer film and the sterilized paper. Moreover, in the package of this embodiment, the sealing strength of the multilayer film 1 and the sterilized paper is preferably 1.0 to 7.7 N/15 mm, and more preferably 1.2 to 6.0 N/15 mm. If the above-mentioned sealing strength is equal to or higher than the lower limit of the above-mentioned preferred range, the sealing performance of the package will be further improved, and if it is below the upper limit, better sealability will be obtained (tear and peeling of fibers during peeling are suppressed) ).

As described above, with the multilayer film of this embodiment, the sealant layer provided as the surface layer contains at least linear low-density polyethylene, and the density of the linear low-density polyethylene is 0.93 or more, so the foregoing The heat-sealed multi-layer film and sterilized paper package has the following excellent effects: it can ensure proper sealing strength, and can suppress the generation of paper residue on the peeling surface of the substrate when peeling the sterilized paper, thereby providing no sanitation. The packaging of the problem.

The packaging system of this embodiment has the structure of the multilayer film 1 and the sterilized paper. When the seal strength of the multilayer film 1 and the sterilized paper is 1.0 to 7.7 (N/15 mm), it is further excellent from the viewpoint of seal strength and easy peelability .

The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific structure is not limited to this embodiment, and includes designs that do not deviate from the scope of the gist of the present invention. For example, the multilayer film 1 shown in FIG. 1 has a structure in which a sealant layer 2 and a base material layer 3 are sequentially stacked, but this is an example and is not limited to this. For example, as shown in FIG. 2, a multilayer film according to an embodiment of the present invention may include a sealant layer 2, a base material layer 30, a base material layer 31, an adhesive resin layer 4 and a pinhole-resistant layer 5 in this order The structure may be formed by alternately laminating two layers of the adhesive resin layer 4 and the pinhole-resistant layer 5 or by alternately laminating three or more layers.

In addition, in the multilayer film 1, a layer having other functions may be newly provided between the layers and the outermost layer on the side opposite to the sealant layer 2. For example, from the viewpoint of imparting oxygen barrier properties to the multilayer film 1, a resin layer composed of an ethylene-vinyl alcohol copolymer resin may be provided. In addition, from the viewpoint of imparting strength to the multilayer film 1, a resin layer composed of polypropylene-based resin (PP) may be provided. In addition, from the viewpoint of imparting flexibility to the multilayer film 1, a resin layer composed of an ethylene-vinyl acetate copolymer layer (EVA layer) or a polyethylene layer (PE layer) may be provided. (Example)

Hereinafter, the present invention will be described in further detail based on Examples and Comparative Examples, but the present invention is not limited to these.

<Fabrication of multilayer film> (Example 1) A multilayer film was produced by the following steps. The multilayer film had the structure shown in FIG. 1, and further provided with an adhesive resin layer and pinhole resistance in the order of lamination shown in FIG. Floor. First, as the resin contained in the pinhole-resistant layer, nylon (manufactured by Ube Industries, Ltd., product number: 1022B) was prepared. In addition, as the resin contained in the adhesive resin layer (hereinafter, simply referred to as "adhesive layer"), an adhesive polyethylene-based resin (manufactured by Mitsui Chemicals, Inc., product number: NF536) was prepared. As the resin contained in the base material layer, polyethylene (manufactured by Ube-Maruzen Polyethlene Co, Ltd, product number: F222NH) was prepared. In addition, as the resin contained in the sealant layer, metallocene catalyst linear low density polyethylene (mLLDPE) resin (manufactured by Ube-Maruzen Polyethlene Co, Ltd., product number: 4040FC, melting point 126°C) and low Density polyethylene (LDPE) (manufactured by Ube-Maruzen Polyethlene Co, Ltd., product number: F222NH, melting point 110°C), and these were mixed (kneaded) in a ratio of 80:20. The density (g/cm ³ ) of the resin contained in the obtained sealant layer was 0.938 g/cm ³ . Next, a multilayer film with a four-layer structure in the order of sealant layer/base material layer/adhesive resin layer/pinhole-resistant layer was produced (laminated) by extrusion processing. The thickness of the sealant layer was 12 μm, the thickness of the base material layer was 68 μm, the thickness of the adhesive resin layer was 14 μm, and the thickness of the pinhole-resistant layer was 16 μm. In addition, the density of the resin contained in the sealant layer was measured using a specific gravity measuring device (Shibayama Scientific Co., Ltd.) according to the density gradient tube method of JIS K7112. In addition, the melting point was measured by differential scanning calorimetry (DSC, manufactured by Hitachi High-Tech Science Corporation, DSC6200), and the temperature was raised from 25°C to 300°C at a heating rate of 5°C/min in a nitrogen atmosphere at a heating rate of -50°C. /min is cooled to 25°C, and the temperature is raised from 25°C to 300°C again at a temperature increase rate of 5°C/min, and the temperature is measured at the time of reheating.

(Example 2) As the resin contained in the sealant layer, metallocene catalyst linear low-density polyethylene (mLLDPE) resin (manufactured by SUMITOMO CHEMICAL COMPANY, LIMITED, product number: FV407, melting point: 124°C) was used instead Except for metallocene catalyst linear low-density polyethylene (mLLDPE) resin (manufactured by Ube-Maruzen Polyethlene Co, Ltd., product number: 4040FC), in the same manner as in Example 1 by extrusion processing A multilayer film with a four-layer structure in the order of sealant layer/base material layer/adhesive resin layer/pinhole-resistant layer was produced (laminated). The density (g/cm ³ ) of the resin contained in the obtained sealant layer was 0.930 g/cm ³ . The thickness of the sealant layer was 14 μm, the thickness of the base material layer was 68 μm, the thickness of the adhesive resin layer was 14 μm, and the thickness of the pinhole-resistant layer was 16 μm.

(Example 3) As the resin contained in the sealant layer, a metallocene catalyst linear low density polyethylene (mLLDPE) resin (manufactured by Prime Polymer Co., Ltd., product number: SP3530, melting point: 97, 121, 125°C) in the same manner as in Example 1 except for replacing the metallocene catalyst linear low-density polyethylene (mLLDPE) resin (manufactured by Ube-Maruzen Polyethlene Co, Ltd., product number: 4040FC) A multilayer film with a four-layer structure in the order of sealant layer/base material layer/adhesive resin layer/pinhole-resistant layer was produced (laminated) by extrusion processing. The density (g/cm ³ ) of the resin contained in the obtained sealant layer was 0.931 g/cm ³ . The thickness of the sealant layer was 14 μm, the thickness of the base material layer was 68 μm, the thickness of the adhesive resin layer was 14 μm, and the thickness of the pinhole-resistant layer was 16 μm.

(Example 4) As the resin contained in the sealant layer, instead of using low density polyethylene (LDPE), only metallocene catalyst linear low density polyethylene (mLLDPE) resin (Ube-Maruzen Polyethlene) was used Co. Ltd., product number: 4040FC, melting point 126°C, density 0.938g/cm ³ ), except that in the same manner as in Example 1, a press sealant was produced (laminated) by extrusion processing Multilayer film with a four-layer structure in the order of layer/base layer/adhesive resin layer/pinhole-resistant layer. The density (g/cm ³ ) of the resin contained in the obtained sealant layer was 0.938 g/cm ³ . The thickness of the sealant layer was 12 μm, the thickness of the base material layer was 68 μm, the thickness of the adhesive resin layer was 14 μm, and the thickness of the pinhole-resistant layer was 16 μm.

(Comparative Example 1) As the resin contained in the sealant layer, a metallocene catalyst linear low density polyethylene (mLLDPE) resin (manufactured by Dow Chemical Company, product number: 5220G, melting point: 102, 113, 124°C) was used ) Instead of metallocene catalyst linear low-density polyethylene (mLLDPE) resin (manufactured by Ube-Maruzen Polyethlene Co, Ltd., product number: 4040FC), except that in the same manner as in Example 1, by extrusion A multilayer film with a four-layer structure in the order of sealant layer/base material layer/adhesive resin layer/pinhole-resistant layer was produced (laminated) by processing. The density (g/cm ³ ) of the resin contained in the obtained sealant layer was 0.915 g/cm ³ . The thickness of the sealant layer was 14 μm, the thickness of the base material layer was 68 μm, the thickness of the adhesive resin layer was 14 μm, and the thickness of the pinhole-resistant layer was 16 μm.

(Comparative Example 2) As the resin contained in the sealant layer, linear low-density polyethylene (LLDPE) resin (made by Prime Polymer Co., Ltd., product number: 2540R, melting point: 121°C) was used instead of metallocene Except for catalyst linear low-density polyethylene (mLLDPE) resin (manufactured by Ube-Maruzen Polyethlene Co, Ltd., product number: 4040FC), it was produced by extrusion processing in the same manner as in Example 1 ( Laminated) a multilayer film with a four-layer structure in the order of sealant layer/base material layer/adhesive resin layer/pinhole-resistant layer. The density (g/cm ³ ) of the resin contained in the obtained sealant layer was 0.923 g/cm ³ . The thickness of the sealant layer was 14 μm, the thickness of the base material layer was 68 μm, the thickness of the adhesive resin layer was 14 μm, and the thickness of the pinhole-resistant layer was 16 μm.

(Comparative Example 3) As the resin contained in the sealant layer, a metallocene catalyst linear low-density polyethylene resin (Ube-Maruzen Polyethlene Co, Ltd., product number: 1540F, melting point: 114°C) was used instead Metallocene catalyst linear low-density polyethylene (mLLDPE) resin (manufactured by Ube-Maruzen Polyethlene Co, Ltd., product number: 4040FC), except that it was processed by extrusion in the same manner as in Example 1. A multilayer film with a four-layer structure in the order of sealant layer/base material layer/adhesive resin layer/pinhole-resistant layer was produced (laminated). The density (g/cm ³ ) of the resin contained in the obtained sealant layer was 0.913 g/cm ³ . The thickness of the sealant layer was 14 μm, the thickness of the base material layer was 68 μm, the thickness of the adhesive resin layer was 14 μm, and the thickness of the pinhole-resistant layer was 16 μm.

<Production of packaging body> After stacking the multilayer films obtained in Examples and Comparative Examples and the sterilization paper so that the sterilization paper side becomes the hot plate side, and placing the Teflon (registered trademark) sheet, use an automatic cup sealing machine in the following Sealing was carried out under the conditions to prepare a sample for evaluation of the package. The peeling is performed in the MD and TD directions of the film.・Sealing pressure: 2.0kgf/cm ² (0.2MPa) ・Sealing time: 3.0 seconds ・Sealing temperature: 130℃, 140℃, 150℃ (at 10℃ intervals, 3 conditions)

<Evaluation> For the evaluation samples of the packaging bodies obtained in Examples and Comparative Examples, heat sealability (sealing strength), evaluation of paper residue on the peeling surface, evaluation of low molecular weight volatile components, evaluation of equipment contamination, and evaluation of molecular weight distribution were carried out And evaluation of hot plate adhesion.

(Evaluation of heat sealability) The evaluation of the heat sealability was performed by measuring the seal strength at a seal width of 15 mm using a tensile tester (manufactured by A&D Company, Limited, TENSILON RTG-1310). The peeling speed was 200 mm/min. Table 1 shows the sealing strength of the evaluation samples prepared at the respective sealing temperatures for the examples and comparative examples.

(Evaluation of paper residue on peeling surface) The evaluation of the paper residue was carried out by using the five evaluation samples described above, and peeling off the cover material and the bottom material of the package that became the evaluation sample. Regarding the evaluation, the peeling surfaces of the cover material and the substrate after peeling were observed to determine whether there was paper remaining on the peeling surface of the substrate. Table 1 shows the number of samples with paper remaining among the evaluation samples prepared at the respective sealing temperatures for the examples and comparative examples.

[Table 1]

(Evaluation of low molecular weight volatile components) For the evaluation of low molecular weight volatile components, thermal decomposition-GC-MS (thermal decomposition device: manufactured by Frontier Laboratories Ltd., PY-2020iD heating furnace type thermal decomposition device, GC: Agilent Technologies, 6890N gas chromatograph, MS: Agilent Technologies, 5975B quality detector) and the linear low-density polyethylene sample contained in the sealant layer is about 27mg, heating conditions 120 ℃ × 10 minutes in a heated atmosphere of helium. Regarding the quantification of the detected components, GC-MS measurement is performed using a known concentration of n-decane in acetone dilution, and the converted quantitative value of the standard sample is calculated by comparing the peak area values of the gas components generated and calculated relative to The weight fraction of the sample weight. Table 2 shows the weight fraction of each linear low-density polyethylene relative to the weight of the sample for the examples and comparative examples.

(Evaluation of equipment pollution) The equipment contamination was evaluated by the following method: the multilayer films obtained in the Examples and Comparative Examples were cut into 10 cm squares, overlapped with aluminum foil, and pressed using a pressing machine under the following conditions, and the low molecular weight components migrated to the aluminum foil were observed . ・Pressing pressure: 10MPa ・Pressing time: 10 minutes ・Pressing temperature: 110℃ The evaluation criteria are shown below. A: The migration area of the low-molecular-weight component relative to the aluminum foil is 5% or less of the entire aluminum foil B: Compared with aluminum foil, the migration area of low molecular weight components is greater than 5% of the entire aluminum foil Table 2 shows the evaluation results for the multilayer films obtained in Examples and Comparative Examples. In addition, in the table, "-" means not evaluated.

[Table 2]

(Evaluation of molecular weight distribution) For the molecular weight distribution (Mw/Mn) of the linear low-density polyethylene of Examples and Comparative Examples, a GPC device (device: PL-GPC220 manufactured by Agilent, column: Agilent PLgel Olexis × 2 roots + Guard) was used. After diluting the linear low-density polyethylene of Examples and Comparative Examples, dichlorobenzene was injected into the column at a temperature of 145°C, a concentration of 0.1 wt/vol%, and a flow rate of 1.0 ml/min, and detected by a differential refractometer The elution amount is obtained from the elution curve obtained. Table 3 shows the molecular weight distribution (Mw/Mn) and number average molecular weight (Mn) of the linear low-density polyethylene of the examples and comparative examples. In addition, in the table, "-" means not evaluated.

(Evaluation of hot plate adhesion) For evaluation of hot plate adhesion, GEA PowerPak ST 420 was used to clean the molded hot plate with ethanol. After 7 hours of operation at a molding temperature of 108°C, a heating time of 9.9 seconds, and no seal, the surface of the hot plate was wiped with a spatula to confirm the presence or absence Attachment builds up. Table 3 shows the presence or absence of deposits on the hot plate for the examples and comparative examples.

[table 3]

As shown in Table 1, in Examples 1 to 4, for all evaluation samples with a sealing temperature of 140°C and 150°C, it was confirmed that the sealing strength was 1.2 N/15 mm or more, and heat sealing was possible in the temperature range of 140°C and 150°C , Excellent heat sealability. In addition, for all evaluation samples with sealing temperatures of 130°C and 140°C, it was confirmed that no paper remained on the peeling surface during peeling. Even if the sealing temperature was 150°C, there was little paper remaining on the peeling surface, and paper residue on the peeling surface was suppressed. On the other hand, when the sealing temperature is 140°C and 150°C, the sealing strength is higher than when the sealing temperature is 130°C. In this way, both the high sealing strength and the effect of suppressing paper residue on the peeling surface are particularly excellent when the sealing temperature is 140°C and 150°C.

On the other hand, in Comparative Examples 1 to 3, in any of the evaluation samples having a sealing temperature of 130° C. or higher, a significant amount of paper remained on the peeling surface. Especially in Comparative Example 3, in all the evaluation samples having a sealing temperature of 130° C. or higher, significant paper residue was generated on the peeling surface.

In addition, for Examples 1, 3, and 4, the results of thermal decomposition-GC-MS are shown in Table 2. From this result, it can be inferred that Example 1 and Example 4 have a lower amount of low-molecular-weight volatile components by GC-MS than Example 3, and therefore, less gas is generated during molding, and equipment contamination can be further prevented.

In addition, for Examples 1 to 3 and Comparative Examples 1 to 3, Table 2 shows the evaluation of equipment contamination by the press. From this result, it can be seen that, compared to Example 3 in which there are many low-molecular-weight volatile components by GC-MS in Example 1, the migration of low-molecular-weight volatile components is large and the equipment is easily contaminated.

In addition, for Examples 1 to 4 and Comparative Examples 1 to 3, the melting point (melting point peak temperature) based on the DSC measurement results is shown in Table 2. From this result, it can be inferred that, compared with Example 3, Examples 1, 2 and 4 have the highest melting point peak temperature of 120° C. or higher and the lowest melting point peak not of 100° C. or lower, so equipment contamination can be further prevented.

Furthermore, according to the results of the molecular weight distribution (Mw/Mn) based on GPC shown in Table 3, Example 1 and Example 4 have a narrower molecular weight distribution and a lower amount of low molecular weight components compared to Example 3 Less, so there is less generation of foreign matter attached to the hot plate during forming. Even if the operation time of the equipment is prolonged, no foreign matter will be generated, which can prevent contamination of the production equipment. [Industry availability]

The multilayer film and packaging body of the present invention may be used as a packaging body for medical devices such as gauze and catheters and medical equipment.

1‧‧‧Multilayer film 2‧‧‧Sealant layer 3‧‧‧ Base layer 30‧‧‧Base layer 1 31‧‧‧Substrate layer 2 4‧‧‧adhesive resin layer 5‧‧‧pinhole resistant layer

FIG. 1 is a schematic cross-sectional view of a multilayer film 1 to which an embodiment of the present invention is applied. 2 is a schematic cross-sectional view of a multilayer film 1 to which an embodiment of the present invention is applied.

1‧‧‧Multilayer film

2‧‧‧Sealant layer

3‧‧‧ Base layer

Claims (10)

A multilayer film having at least a sealant layer provided as a surface layer, The sealant layer contains at least linear low-density polyethylene, and the density of the linear low-density polyethylene is 0.93 or more. For example, the multi-layer film of patent application item 1, where, The sealant layer further includes low density polyethylene, and the mass ratio of the linear low density polyethylene to the low density polyethylene is in the range of 50:50 to 99:1. The multilayer film according to item 1 or 2 of the patent application includes a base material layer which is provided adjacent to the sealant layer and contains a polyethylene-based resin. For example, the multi-layer film of patent application item 3, in which The base material layer contains linear low-density polyethylene. For example, the multi-layer film of patent application item 3 or 4, wherein, The thickness ratio of the sealant layer to the base material layer is in the range of 1:0.5 to 1:15. The multilayer film according to any one of items 1 to 5 of the patent application scope, wherein, The low molecular weight volatile component of the linear low-density polyethylene contained in the sealant layer is 0.1 wt% or less. For the multilayer film according to any one of patent application items 1 to 6, wherein, The molecular weight distribution (Mw/Mn) of the linear low-density polyethylene contained in the sealant layer is 7.0 or less, and the number average molecular weight Mn of the linear low-density polyethylene is 20,000 or more. For example, the multilayer film according to any one of items 1 to 7 in the patent application range can be heat-sealed with sterilized paper in the range of 135 to 155°C. A packaging body with a multilayer film and sterilized paper according to any one of the patent application items 1 to 8, Moreover, at least a part of the sealant layer of the multilayer film is heat sealed to the surface of the sterilized paper. For example, the packaging body of item 9 of the patent application scope, where, The sealing strength of the multilayer film and the sterilized paper is 1.0-7.7 (N/15mm).

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