JP7036100B2 - Package - Google Patents

Description

The present invention relates to multilayer films and packages.

In recent years, as a medical package, a deep-drawn package (hereinafter, also referred to as "deep-draw package") has been used. The deeply squeezed package has a bottom material made of a multilayer film having a recess formed in the center and a lid material made of polyethylene non-woven fabric, sterilized paper, etc. (hereinafter, also referred to as "PE non-woven fabric, etc."), such as a heat seal. Joined by. Then, a gauze for business use, a cotton swab, a medical device, or the like is housed in the above-mentioned recess.

Conventionally, as a bottom material used for medical packaging, a multilayer film obtained by laminating a polyester film or nylon film and a heat-sealable resin film (lamination method) is widely and generally used. On the other hand, as the lid material, polyethylene non-woven fabric or sterilized paper is used as described above from the viewpoint of air permeability of the sterilized gas in the sterilization process.

By the way, the medical packaging is required to be easy to open depending on the mode of use. Further, as the lid material of the medical packaging body, a polyethylene non-woven fabric is selected from the viewpoint of placing importance on hygiene. Since the polyethylene non-woven fabric coated with an adhesive and imparted easy-opening property is expensive and the gas permeability is also lowered, the easy-peelable function is imparted to the multilayer film side to be sealed with the polyethylene non-woven fabric. A structure in which an easily peelable resin layer (hereinafter, also referred to as "easy peel layer") is provided on the sealing side with a PE non-woven fabric or the like as a multilayer film used as a bottom material in order to impart easy-opening property to a medical package. Is known (Patent Document 1). Further, a coextruded multilayer film for deep drawing molding having a polyamide resin, a polyethylene non-woven fabric or sterilized paper at 135 ° C. or lower, a heat-sealing seal layer, and an easy peel layer having delamination property between the seal layers is known. (Patent Document 2).

Japanese Unexamined Patent Publication No. 2014-162162 Japanese Unexamined Patent Publication No. 2014-19006

A part of the multilayer film as a bottom material used for medical packaging may adhere to the molding hot plate during molding, and when the adhered foreign matter is generated, the multilayer film is manufactured by the adhered foreign matter. The problem arises that the equipment is contaminated.

The present invention has been made in view of the above circumstances, and is a multilayer film and a packaging body capable of suppressing the generation of adhered foreign matter on a molding hot plate during molding and preventing equipment contamination due to the adhered foreign matter. The challenge is to provide.

In order to achieve the above object, the present invention has adopted the following configuration.
[1] A sealant layer containing at least a metallocene-catalyzed linear low-density polyethylene provided so as to be a surface layer, and a group provided adjacent to the sealant layer and containing a linear low-density polyethylene-based resin. At least with a material layer,
The molecular weight distribution (Mw / Mn) of the metallocene-catalyzed linear low-density polyethylene is 7.0 or less, and the number average molecular weight Mn of the metallocene-catalyzed linear low-density polyethylene is 20000 or more.
The content of the metallocene-catalyzed linear low-density polyethylene in the sealant layer is 50 to 100% by mass.
The density of the metallocene-catalyzed linear low-density polyethylene in the sealant layer is 0.92 or less.
Sterilized paper and heat seal are possible in the range of 135 to 160 ° C.
The metallocene-catalyzed linear low-density polyethylene is provided with a multilayer film and sterile paper in which the highest melting point peak temperature by differential scanning calorimetry is 120 ° C. or higher and the lowest melting point peak is not present at 100 ° C. or lower.
At least a portion of the sealant layer of the multilayer film is heat-sealed on the surface of the sterile paper.
A package having a sealing strength between the multilayer film and the sterilized paper in the range of 145 to 155 ° C. of 1.2 to 6.0 (N / 15 mm).
[2] The package according to [1], wherein the ratio of the thickness of the sealant layer to the base material layer is in the range of 1: 0.5 to 1:15.

As described above, the multilayer film of the present invention includes at least a sealant layer containing at least a linear low-density polyethylene provided so as to be a surface layer, and has a molecular weight distribution of the linear low-density polyethylene (the molecular weight distribution of the linear low-density polyethylene). Since Mw / Mn) is 7.0 or less and the number average molecular weight Mn of the linear low-density polyethylene is 20000 or more, foreign matter adhered to the hot plate during molding is generated. It has an excellent effect of being suppressed and preventing equipment contamination due to the adhered foreign matter.

It is sectional drawing of the multilayer film 1 which is one Embodiment to which this invention is applied. It is sectional drawing of the multilayer film 1 which is one Embodiment to which this invention is applied.

Hereinafter, a multilayer film and a package to which the present invention is applied will be described in detail. In addition, in the drawings used in the following explanation, in order to make the features easy to understand, the featured parts may be enlarged for convenience, and the dimensional ratios of each component may not be the same as the actual ones. do not have.

<Multilayer film>
First, a configuration of a multilayer film according to an embodiment to which the present invention is applied will be described. FIG. 1 is a schematic cross-sectional view of a multilayer film 1 according to an embodiment to which the present invention is applied. As shown in FIG. 1, the multilayer film 1 of the present embodiment is roughly configured by including a sealant layer 2 provided as a surface layer and a base material layer 3 provided adjacent to the sealant layer 2. ing. Further, as shown in FIG. 2, the multilayer film 1 of the present embodiment has a sealant layer 2 provided as a surface layer, a base material layer 3 provided adjacent to the sealant layer 2, and a base material layer 3. It may be roughly configured with another resin layer laminated on the top. The multilayer film 1 of the present embodiment can be used as a film for a bottom material of a package, particularly a medical package.

(Sealant layer)
The sealant layer 2 is one of the outermost surfaces of the multilayer film, and is a resin layer provided for imparting easy-opening property. The exposed surface (sometimes referred to as the first surface in the present specification) of the sealant layer 2 opposite to the base material layer 3 is the outermost surface of one of the multilayer films 1.
The first surface 2a of the sealant layer 2 is a sealing surface, and a part of the area thereof is overlapped with the surface of another film such as sterilized paper and heat-sealed, and as a result, a package is formed. On the other hand, a part of the unsealed area constitutes a storage portion for the contents in the package.

The sealant layer 2 contains at least linear low-density polyethylene, and the molecular weight distribution (Mw / Mn) of the linear low-density polyethylene is 7.0 or less, preferably 5.0 or less, more preferably 4.0. Below, it is more preferably 3.5 or less, and the number average molecular weight Mn of the linear low-density polyethylene is 20,000 or more, preferably 25,000 or more, more preferably 28,000 or more, still more preferably 30,000 or more. .. When the molecular weight distribution (Mw / Mn) of the linear low-density polyethylene is 7.0 or less and the number average molecular weight Mn of the linear low-density polyethylene is 20000 or more, the multilayer film is formed. In addition, the generation of adhered foreign matter on the molded hot plate is suppressed, and equipment contamination due to the adhered foreign matter can be prevented.
In addition, in this specification, Mw (weight average molecular weight) and Mn (number average molecular weight) are both values obtained from the polystyrene conversion value measured by the gel permeation chromatography (GPC) method.

The resin that can be used for the sealant layer 2 is not particularly limited as long as it is a resin containing linear low density polyethylene (LLDPE) having the above molecular weight distribution (Mw / Mn) and a number average molecular weight Mn, but is not limited to metallocene. Resins containing catalytic linear low density polyethylene (mLLDPE) are preferred.
Further, the linear low density polyethylene (LLDPE) may have one m-peak or two or more peaks in the DSC measurement, and the highest melting point peak temperature may be 120 ° C. or higher. preferable. More preferably, a resin having a highest melting point peak temperature of 120 ° C. or higher and a lowest melting point peak of 100 ° C. or lower is preferable. More preferably, a resin having a highest melting point peak temperature of 120 ° C. or higher and a lowest melting point peak of 110 ° C. or lower is preferable. According to the above, the resin does not melt due to heating during molding, and equipment contamination can be prevented.

The density of the linear low-density polyethylene may be, for example, less than 0.93 or less than 0.92. When the density of the linear low-density polyethylene is in the above range, the low-temperature sealing property is improved.

Further, the sealant layer 2 may further contain low density polyethylene (LDPE).

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

The content of the linear low-density polyethylene in the total resin constituting the sealant layer 2 is preferably 30 to 100% by mass, 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, preferably 50 to 100% by mass. Is more preferable.
When the content of the linear low-density polyethylene is within the above-mentioned preferable range, the effect of suppressing the generation of adhered foreign matter on the molding hot plate becomes higher when the multilayer film is molded. Further, the heat seal strength is stable, and when the sterilized paper is peeled off, the paper residue on the sealant layer 2 is suppressed.

The sealant layer 2 may contain an additive from the viewpoint of improving the low temperature heat sealability. Examples of the additive include a terpene resin (for example, "Hirodyne series" manufactured by Yasuhara Chemical Co., Ltd.) and the like.

The thickness of the sealant layer 2 is preferably 3 to 70 μm, more preferably 5 to 45 μm. When the thickness is not less than the lower limit of the preferable range, high sealing strength can be obtained when heat-sealing with sterilized paper, and when it is not more than the upper limit, the effect of easy opening becomes high when opening.

(Base layer)
The base material layer (also referred to as a core layer) 3 is a resin layer provided adjacent to the above-mentioned sealant layer 2 for the purpose of imparting 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 is a resin that can impart the above functions, and examples thereof include polyethylene-based resins.

Examples of the polyethylene-based resin include a homopolymer of ethylene such as low-density polyethylene (LDPE) resin, linear low-density polyethylene (LLDPE) resin, medium-density polyethylene (MDPE) resin, and high-density polyethylene (HDPE) resin; Ethylene-vinyl acetate copolymer (EVA) resin, ethylene-methylmethacrylate copolymer (EMMA) resin, ethylene-ethylacrylate copolymer (EEA) resin, ethylene-methylacrylate copolymer (EMA) resin, ethylene- Ethylene-based copolymers such as ethyl acrylate-maleic anhydride copolymer (E-EA-MAH) resin, ethylene-acrylic acid copolymer (EAA) resin, ethylene-methacrylic acid copolymer (EMAA) resin; ionomer (ION) ) Resin or the like is used alone or in combination of two or more.
The above-mentioned LLDPE is preferable as the polyethylene resin. By using LLDPE as the resin contained in the base material layer 3, more stable heat seal strength (synergistic effect with the resin containing 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 two or more layers as shown in FIG. For example, by making the base material layer 3 composed of a plurality of layers of different materials, characteristics such as 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, more preferably 30 to 100 μm. When the thickness is at least the lower limit of the preferable range, the flexibility of the multilayer film 1 is improved, and when it is at least the upper limit, more stable sealing strength can be obtained.

In the multilayer film 1 of the present embodiment, the thickness ratio of the sealant layer 2 and the base material layer 3 described above is preferably in the range of 1: 0.5 to 1:15, and is preferably 1: 0.5 to 1:15. The range of 1:10 is more preferable, and the range of 1: 2 to 1:10 is more preferable. When the above-mentioned ratio is not less than the lower limit value in the above preferable range, the effect of preventing curling of the package can be obtained, and when it is not more than the upper limit value, more stable sealing strength can be obtained.

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

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

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

The thickness of the adhesive resin layer 4 is not particularly limited as long as each layer can be bonded with a required adhesive strength, but is preferably 2 to 30 μm, 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. The pinhole-resistant layer 5 preferably contains a polyamide resin from the viewpoint of improving pinhole resistance. 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 and 610-nylon. , 611-Nylon, 612-Nylon, 6T-Nylon, 6I Nylon, 6-Nylon and 66-Nylon Copolymer (Nylon 6/66), 6-Nylon and 610-Nylon Copolymer, 6-Nylon and 611-Nylon Copolymer, 6-nylon and 12-nylon copolymer (nylon 6/12), 6-nylon and 612 nylon copolymer, 6-nylon and 6T-nylon copolymer, 6-nylon and 6I-nylon copolymer, 6-nylon And 66-nylon and 610-nylon copolymer, 6-nylon and 66-nylon and 12-nylon copolymer (nylon 6/66/12), 6-nylon and 66-nylon and 612-nylon copolymer, 66-nylon And 6T-nylon copolymer, 66-nylon and 6I-nylon copolymer, 6T-nylon and 6I-nylon copolymer, 66-nylon and 6T-nylon and 6I-nylon copolymer, amorphous nylon and the like. .. Among them, 6-nylon, 12-nylon, 66-nylon, nylon 6/66, nylon 6/12, nylon 6/66/12 and the like are preferable from the viewpoint of heat resistance, mechanical strength, and availability. , 6-Nylon is more preferred.

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

(Additive)
In the multilayer film 1 of the present embodiment, known lubricants and additives are appropriately added to the sealant layer 2 and the base material layer 3 described above for the purpose of preventing slipperiness and blocking and imparting antifogness, if necessary. It may be given. For the purpose of slipperiness and prevention of blocking, organic lubricants such as oleic acid amide and erucic acid amide, and inorganic lubricants such as silica, zeolite and calcium carbonate can be mentioned. Further, in order to impart anti-fog property, a already known surfactant or the like can be appropriately used.

<Manufacturing method of multilayer film>
Next, an example of the above-mentioned manufacturing method of the multilayer film 1 will be described.
The method for producing the multilayer film 1 described above is not particularly limited, but is a coextrusion T-die method such as a feed block method or a multi-manifold method in which a resin or the like as a raw material is melt-extruded by several extruders. Examples thereof include an air-cooled or water-cooled coextrusion inflation method and a laminating method. Among these, the method of forming a film by the coextrusion T-die method is particularly preferable because it is excellent in controlling the thickness of each layer.

As the laminating method, a dry laminating method, an extrusion laminating method, a hot melt laminating method, a wet laminating method, a thermal (heat) laminating method, etc., in which a single-layer sheet or film forming each layer is bonded together using an appropriate adhesive, etc. And those methods can be used in combination. Further, it may be laminated by a coating method.

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

The sterilizing paper applicable to the package of the present embodiment is heat-sealable with a sealant layer, has breathability, prevents the permeation of bacteria through the sterilizing paper (has sterilizing property), and is sterilized. The sheet is not particularly limited as long as it is a sheet that can be treated and whose main constituent material is paper. Examples of the sterilized paper include "Medica D (manufactured by Oji F-Tex)" and the like.

When the package of the present embodiment is used as a medical package, the sterile paper preferably has small holes to the extent that it can exhibit breathability and antibacterial properties. Specifically, it is preferable that the sterilized paper is composed of fibers in the range of 0.0001 to 20 dtex and has a basis weight of 10 to 300 g / m ² .

The package of the present embodiment is formed by deep-drawing the bottom material, filling it with medical equipment such as gauze and a catheter, and heat-sealing it with a lid material. , Can be used as a deep-drawn package. In particular, when the above-mentioned multilayer film is used as the bottom material of the deeply drawn package and sterilized paper is used as the lid material, a good deeply drawn package can be obtained.

The package of the present embodiment can be produced by adhering a multilayer film used as a bottom material and sterilized paper used as a lid material by an adhesive means such as a heat seal. Specifically, a package can be produced by heat-sealing a multilayer film and sterilized paper in a temperature range of preferably 135 to 160 ° C.
Further, in the package of the present embodiment, the sealing strength between the multilayer film 1 and the sterilized paper is preferably 1.0 to 7.7 N / 15 mm, preferably 1.2 to 6.0 N / 15 mm. Is more preferable. When the above-mentioned sealing strength is at least the lower limit of the above-mentioned preferable range, the sealing property of the package becomes higher, and when it is at least the upper limit, better opening property (fiber tearing and fluffing during peeling). Suppression) is obtained.

The package body of the second embodiment of the present embodiment is a package body including a lid material and a bottom material, and the package body is composed of the lid material and the heat seal of the bottom material, and the lid. Either or both of the material and the bottom material are made of the above-mentioned multilayer film.

Among the lid material and the bottom material, known materials can be used as the material other than the multilayer film of the present embodiment described above.

The package of the present embodiment can be used as a deep-drawn package by deep-drawing the bottom material, filling it with contents such as food, covering it with a lid material, and heat-sealing it. For example, when either the lid material or the bottom material is the above-mentioned multilayer film, it is excellent in terms of sealing strength and easy peeling property. Further, since both the lid material and the bottom material are the above-mentioned multilayer films, the sealing strength is excellent.

The package of the present embodiment is in the same manner as in the case of a known similar package, except that the multilayer film of the above-described embodiment is used as one or both of the lid material and the bottom material. Can be made.
That is, the package of the present embodiment can be manufactured by superimposing the lid material and the bottom material so as to form a storage portion and heat-sealing them.
At the time of manufacturing the package, the contents are stored in the storage portion before the heat seal between the lid material and the bottom material. Then, if necessary, the lid material and the bottom material are heat-sealed while the inside of the storage portion is evacuated.

As described above, according to the multilayer film of the present embodiment, at least a sealant layer containing at least a linear low-density polyethylene provided so as to be a surface layer is provided, and the linear low-density polyethylene is provided. Since the molecular weight distribution (Mw / Mn) is 7.0 or less and the number average molecular weight Mn of the linear low-density polyethylene is 20000 or more, adhesion on a molding hot plate when forming a multilayer film It has an excellent effect that the generation of foreign matter is suppressed, equipment contamination due to the adhered foreign matter can be prevented, and a multilayer film and a package can be manufactured without causing equipment contamination.

The package of the present embodiment has a structure including a multilayer film 1 and sterilized paper, or a structure including a lid material and a bottom material, and one or both of the lid material and the bottom material is a multilayer film. It consists of 1.
The package including the multilayer film 1 and the sterilized paper has a sealing strength when the sealing strength between the multilayer film 1 and the sterilized paper is 1.0 to 7.7 (N / 15 mm). In terms of easy peeling, it becomes even better.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs and the like within a range that does not deviate from the gist of the present invention. For example, the multilayer film 1 shown in FIG. 1 has a structure in which the sealant layer 2 and the base material layer 3 are laminated in this order, but this is an example, and the present invention is not limited thereto. For example, in the multilayer film according to the embodiment of the present invention, as shown in FIG. 2, the sealant layer 2, the base material layer 30, the base material layer 31, the adhesive resin layer 4, and the pinhole resistant layer 5 are laminated in this order. The adhesive resin layer 4 and the pinhole-resistant layer 5 may be alternately laminated by two layers each, or three or more layers may be alternately laminated. It may be.

Further, the multilayer film 1 may be newly provided with a layer having another function between each layer or between the outermost layers on the opposite side of the sealant layer 2. For example, from the viewpoint of imparting oxygen gas barrier properties to the multilayer film 1, a resin layer made of an ethylene-vinyl alcohol copolymer resin may be provided. Further, from the viewpoint of imparting strength to the multilayer film 1, a resin layer made of polypropylene-based resin (PP) may be provided. Further, from the viewpoint of imparting flexibility to the multilayer film 1, a resin layer made of an ethylene-vinyl acetate copolymer layer (EVA layer) or a polyethylene layer (PE layer) may be provided.

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

<Manufacturing of multilayer film>
(Example 1)
A multilayer film having the configuration shown in FIG. 1 and further provided with an adhesive resin layer and a pinhole-resistant layer in the stacking order shown in FIG. 2 was produced by the following procedure.
First, nylon (manufactured by Ube Industries, Ltd., product number: 1022B) was prepared as a resin contained in the pinhole-resistant layer.
Further, as a resin contained in the adhesive resin layer (hereinafter, simply referred to as “adhesive layer”), an adhesive polyethylene resin (manufactured by Mitsui Chemicals, Inc., product number: NF536) was prepared.
The resin contained in the base material layer is a metallocene-catalyzed linear low-density polyethylene (mLLDPE) resin (manufactured by Dow Chemical Co., Ltd., product number: 5220G, molecular weight distribution (Mw / Mn): 3.1, number average molecular weight Mn. : 3.08E + 4, melting point: 102, 113, 124 ° C.) was prepared.
Further, as the resin contained in the sealant layer, a metallocene-catalyzed linear low-density polyethylene (mLLDPE) resin (manufactured by Dow Chemical Co., Ltd., product number: 5220G) was prepared as in the base material layer. The density of the resin contained in the sealant layer (g / cm ³ ) was 0.915 g / cm ³ .
Next, a multilayer film having a four-layer structure in the order of a sealant layer / a base material layer / an adhesive resin layer / a pinhole-resistant layer was produced (laminated) by extrusion processing.
The combined thickness of the sealant layer and the base material layer was 65 μm, the thickness of the adhesive resin layer was 11 μm, and the thickness of the pinhole-resistant layer was 14 μm.
The molecular weight distribution (Mw / Mn) of the metallocene-catalyzed linear low-density polyethylene was determined by using a GPC device (device: PL-GPC220 manufactured by Agent, column: Agent PLgel Olexis x 2 + Guard). After elution of the density polyethylene with ortho-dichlorobenzene, the polyethylene 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 the elution amount was detected by a differential refraction meter. Obtained from the curve.
The density of the resin contained in the sealant layer was measured using a specific gravity measuring device (Shibayama Kagaku Kikai Seisakusho) based on the density gradient tube method of JIS K7112.
The melting point is raised to 25 ° C to 25 ° C in a nitrogen atmosphere at a heating rate of 5 ° C / min by differential scanning calorimetry (DSC, manufactured by Hitachi High-Tech Science Co., Ltd., DSC6200). It was cooled at a rate of −50 ° C./min, heated again to 25 ° C. to 300 ° C. at a heating rate of 5 ° C./min, and measured at the time of re-heating.

(Example 2)
As the resin contained in the sealant layer, instead of the metallocene-catalyzed linear low-density polyethylene (mLLDPE) resin (manufactured by Dow Chemical Co., Ltd., product number: 5220G), the metallocene-catalyzed linear low-density polyethylene (mLLDPE) resin (Ube Maruzen) The sealant layer / group is the same as in Example 1 except that the product number: 4040FC, molecular weight distribution (Mw / Mn, melting point 126 ° C.): 3.2, number average molecular weight Mn: 2.57E + 4) manufactured by Polyethylene Co., Ltd. is used. A multi-layer film having a four-layer structure in the order of 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 0.938 g / cm ³ .
The thickness of the sealant layer was 10 μm, the thickness of the base material layer was 55 μm, the thickness of the adhesive resin layer was 10 μm, and the thickness of the pinhole-resistant layer was 15 μm.

(Comparative Example 1)
As the resin contained in the sealant layer, instead of the metallocene-catalyzed linear low-density polyethylene (mLLDPE) resin (manufactured by Dow Chemical Co., Ltd., product number: 5220G), the metallocene-catalyzed linear low-density polyethylene (mLLDPE) resin (prime polymer) is used. The same as in Example 1 except that the product number: SP3530, molecular weight distribution (Mw / Mn): 7.7, number average molecular weight Mn: 1.37E + 4, melting point: 97, 121, 125 ° C.) is used. A multi-layer film having a four-layer structure in the order of a sealant layer / a base material layer / an adhesive resin layer / a pinhole-resistant layer was produced (laminated) by extrusion processing. The density of the resin contained in the sealant layer (g / cm ³ ) was 0.931 g / cm ³ .
The thickness of the sealant layer was 8 μm, the thickness of the base material layer was 58 μm, the thickness of the adhesive resin layer was 12 μm, and the thickness of the pinhole-resistant layer was 14 μm.

<Manufacturing of the package of the first embodiment>
The multilayer films obtained in Examples and Comparative Examples and the sterilized paper are laminated so that the sterilized paper side faces the hot plate side, a Teflon (registered trademark) sheet is placed on the layers, and then the following is used using an auto cup sealer. A sample for evaluation of the package was prepared by sealing under the conditions. The peeling was performed in the MD direction and the TD direction of the film.
-Seal pressure: 0.55 MPa
-Seal time: 3.0 seconds-Seal temperature: 145 ° C, 150 ° C, 155 ° C (at 10 ° C intervals, 3 conditions)

<Evaluation>
With respect to the evaluation samples of the package of the first embodiment obtained in Examples and Comparative Examples, the heat sealability (seal strength), the paper residue on the peeled surface were evaluated, and the hot plate adhesion was evaluated.

(Evaluation of heat sealability)
The heat sealability was evaluated by measuring the seal strength at a seal width of 15 mm using a tensile tester (TENSILON RTG-1310, manufactured by A & D Co., Ltd.). The peeling speed was 200 mm / min. Table 1 shows the seal strengths of the evaluation samples prepared at each seal temperature for Examples and Comparative Examples.

(Evaluation of paper residue on peeled surface)
The evaluation of the paper residue was performed by using the above five evaluation samples and peeling off the lid material and the bottom material of the package to be the evaluation samples.
In the evaluation, the peeled surfaces of the lid material and the bottom material after peeling were observed, and the presence or absence of paper residue on the peeled surface of the bottom material was determined. Table 1 shows the number of samples with paper residue in the evaluation samples prepared at each sealing temperature for Examples and Comparative Examples.

(Evaluation of hot plate adhesion)
For the evaluation of hot plate adhesion, GEA PowerPak ST 420 was used. After cleaning the hot plate with alcohol, the hot plate surface was operated for 7 hours under the conditions of molding temperature 108 ° C, heating time 9.9 seconds, and no seal. Was rubbed with a spatula to confirm the presence or absence of deposits. Table 1 shows the presence or absence of hot plate deposits in Examples and Comparative Examples.

As shown in Table 1, in Examples 1 and 2, in the evaluation samples of the packages of all the first embodiments having the sealing temperatures of 150 ° C. and 155 ° C., the sealing strength was 1.2 N / 15 mm or more and 150 ° C. It was confirmed that the heat-sealing was possible in the temperature range of 155 ° C. and the heat-sealing property was excellent. Further, in the evaluation samples of the packages of all the first embodiments, it was confirmed that there was no paper residue on the peeled surface when peeled.
On the other hand, when the sealing temperature was 150 ° C. and 155 ° C., the sealing strength was higher than when the sealing temperature was 145 ° C. As described above, it was particularly excellent in both the high sealing strength and the effect of suppressing the paper residue on the peeled surface when the sealing temperature was 150 ° C. and 155 ° C.

Further, from the results of the molecular weight distribution (Mw / Mn) and the number average molecular weight (Mn) of the linear low-density polyethylene by GPC, Examples 1 and 2 have a narrower molecular weight distribution than Comparative Example 1 (Mn). It was confirmed that Mw / Mn ≦ 3.2) and the amount of low molecular weight components were small (Mn ≧ 25700). In the multilayer films of Examples 1 and 2, the generation of foreign matter adhering to the hot plate is suppressed during molding, and the generation of foreign matter adhering to the hot plate is suppressed even if the equipment operating time is long, thereby preventing contamination of the production equipment. Was possible.

<Manufacturing of the package of the second embodiment>
Two multilayer films obtained in Examples and Comparative Examples were overlapped so that their respective sealing surfaces were in contact with each other and one outermost layer surface (nylon surface) was on the hot plate side, and a Teflon (registered trademark) sheet was placed on the film. After that, a sample for evaluation of the package was prepared by sealing with an auto cup sealer under the following conditions. The peeling was performed in the MD direction and the TD direction of the film.
-Seal pressure: 0.55 MPa
-Seal time: 3.0 seconds-Seal temperature: 120 ° C, 125 ° C, 130 ° C (3 conditions at 5 ° C intervals)

<Evaluation>
The heat sealability (seal strength) and the hot plate adhesion were evaluated for the evaluation samples of the packages of the second embodiment obtained in Examples and Comparative Examples.

(Evaluation of heat sealability)
The heat sealability was evaluated by measuring the seal strength at a seal width of 15 mm using a tensile tester (TENSILON RTG-1310, manufactured by A & D Co., Ltd.). The peeling speed was 200 mm / min. Table 2 shows the seal strengths of the evaluation samples prepared at each seal temperature for Examples and Comparative Examples.

(Evaluation of hot plate adhesion)
For the evaluation of hot plate adhesion, GEA PowerPak ST 420 was used. After cleaning the hot plate with alcohol, the hot plate surface was operated for 7 hours under the conditions of molding temperature 108 ° C, heating time 9.9 seconds, and no seal. Was rubbed with a spatula to confirm the presence or absence of deposits. Table 2 shows the presence or absence of hot plate deposits in Examples and Comparative Examples.

As shown in Table 2, in Examples 1 and 2, the heat-sealed multilayer film could not be peeled off in the evaluation samples of the packages of all the second embodiments having the sealing temperatures of 120 ° C., 125 ° C. and 130 ° C. , Had high heat sealability.

Further, in the multilayer films of Examples 1 and 2, the generation of adhered foreign matter on the hot plate is suppressed at the time of molding, and the generation of adhered foreign matter is suppressed even if the equipment operating time is long, so that the production equipment is contaminated. It was possible to prevent it.

The multilayer film and package of the present invention can be used as a package for medical instruments such as gauze and catheters, a package for medical devices, and a package for storing foods and the like.

1 ... Multilayer film 2 ... Sealant layer 3 ... Base material layer 30 ... Base material layer 1
31 ... Base material layer 2
4 ... Adhesive resin layer 5 ... Pinhole resistant layer

Claims (2)

A sealant layer containing at least a metallocene-catalyzed linear low-density polyethylene provided to be a surface layer, and a base material layer provided adjacent to the sealant layer and containing a linear low-density polyethylene-based resin. At least prepare
The molecular weight distribution (Mw / Mn) of the metallocene-catalyzed linear low-density polyethylene is 7.0 or less, and the number average molecular weight Mn of the metallocene-catalyzed linear low-density polyethylene is 20000 or more.
The content of the metallocene-catalyzed linear low-density polyethylene in the sealant layer is 50 to 100% by mass.
The density of the metallocene-catalyzed linear low-density polyethylene in the sealant layer is 0.92 or less.
Sterilized paper and heat seal are possible in the range of 135 to 160 ° C.
The metallocene-catalyzed linear low-density polyethylene is provided with a multilayer film and sterile paper in which the highest melting point peak temperature by differential scanning calorimetry is 120 ° C. or higher and the lowest melting point peak is not present at 100 ° C. or lower.
At least a portion of the sealant layer of the multilayer film is heat-sealed on the surface of the sterile paper.
A package having a sealing strength between the multilayer film and the sterilized paper in the range of 145 to 155 ° C. of 1.2 to 6.0 (N / 15 mm). The package according to claim 1, wherein the ratio of the thickness of the sealant layer to the base material layer is in the range of 1: 0.5 to 1:15.

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