JP2021154606A - Multilayer film and package - Google Patents

Abstract

To provide a multilayer film which suppresses variation in thicknesses of a sealant layer and reduces cut of a layer and thereby improves a yield, and can suppress variation in peeling strengths of the sealant layer, and a package having desired easy peelability to a non-woven fabric made of polyethylene.SOLUTION: A multilayer film 1 has at least a sealant layer 2 provided as a surface layer, in which the sealant layer 2 contains at least a first resin having a melting point of 70-110°C and a second resin having a melting point of 130-200°C, and a melt flow rate of the first resin is 3 g/10 min or more, and in the sealant layer 2, a ratio of a content of the first resin with respect to the total mass of the sealant layer 2 is 51-99%, and a ratio of a content of the second resin with respect to the total mass thereof is 1-49%.SELECTED DRAWING: Figure 1

Description

The present invention relates to multilayer films and packages.

In recent years, a deep-drawn package (hereinafter, also referred to as a "deep-draw package") has been used as a medical package. In a deeply drawn package, 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.") are heat-sealed. It is joined by such as. Commercial gauze, cotton swabs, medical instruments, etc. are housed in the recesses described above.

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

By the way, 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. Polyethylene non-woven fabric coated with an adhesive to give easy-opening property is expensive, and gas permeability is also lowered. Therefore, the easy-peeling function is imparted to the multilayer film side to be sealed with the polyethylene non-woven fabric. .. In order to impart easy-opening property to medical packaging, 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. It is known (Patent Document 1). Further, a coextruded multilayer film for deep drawing molding having a polyamide resin, a non-woven fabric or sterilized paper made of polyethylene at 135 ° C. or lower, a sealant layer capable of heat-sealing, and an easy peel layer having delamination property with the sealant layer is known. (Patent Document 2).

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

However, when a multilayer film used for a medical packaging or the like is manufactured by a coextrusion T-die method such as a feed block method in which a resin or the like as a raw material is melt-extruded, the sealant layer does not spread to the edge of the multilayer film. Yield may be deteriorated due to variations in the thickness of the sealant layer or formation of regions without the sealant layer on both ends in the width direction of the film. Furthermore, when the sealant layer contains two different types of resin, if the ratio of the resin in both sealant layers is different, the sealant layer will have a sea-island structure, but if there is a difference in the sea-island structure between the central part and the end part, the center The peel strength varies between the part and the end.

The present invention has been made in view of the above circumstances, and the variation in the thickness of the sealant layer is suppressed, the yield is improved by reducing the regions without the sealant layer on both end sides in the width direction of the film, and further. An object of the present invention is to provide a multilayer film in which variations in the peeling strength of the sealant layer are suppressed, and a package.

In order to achieve the above object, the present invention has adopted the following configuration.
[1] At least a sealant layer provided so as to be a surface layer is provided.
The sealant layer contains a first resin having a melting point of at least 70 to 110 ° C. and a second resin having a melting point of 130 to 200 ° C.
The melt flow rate of the first resin is 3 g / 10 min or more, and the melt flow rate is 3 g / 10 min or more.
In the sealant layer, the ratio of the content of the first resin to the total mass of the sealant layer is 51 to 99%, and the ratio of the content of the second resin is 1 to 49%. the film.
[2] The sealant layer has a sea-island structure, the second resin is present in the island phase, and the center line connecting the centers in the width direction of the sealant layer is directed toward both ends in the width direction of the sealant layer. The region up to a distance of 10% with respect to the width of the sealant layer is the central portion, and the region from both ends in the width direction of the sealant layer to the distance of 10% with respect to the width of the sealant layer is the end portion. When the sealant layer is viewed from above the surface in a plan view, the maximum value of the line segment connecting the two points on the surface of the island phase existing in the central portion is obtained, and the average value L1 is calculated. When the maximum value of the line segment connecting two points on the surface of the island phase existing at the end is obtained and the average value L2 is calculated, L1: L2 is 1: 0.7 to 1: 1. , [1].
[3] The multilayer film according to [1] or [2], wherein the first resin contains a polyethylene-based resin.
[4] The multilayer film according to [3], wherein the polyethylene-based resin contains at least one selected from the group consisting of an ethylene homopolymer and an ethylene-based copolymer.
[5] The multilayer film according to any one of [1] to [4], wherein the second resin contains polypropylene.
[6] The multilayer film according to [4] or [5], wherein the ethylene-based copolymer contains an ethylene-vinyl acetate copolymer.
[7] The multilayer film according to [5] or [6], wherein the polypropylene contains homopolypropylene.
[8] The multilayer film according to any one of [1] to [7], which is provided adjacent to the sealant layer and includes a base material layer containing a polyethylene-based resin.
[9] The multilayer film according to [8], wherein the base material layer contains a linear low-density polyethylene resin.
[10] The multilayer film according to [8] or [9], wherein the ratio of the thickness of the sealant layer to the base material layer is in the range of 1: 4 to 1:12.
[11] The multilayer film according to any one of [1] to [10], wherein the multilayer film can be heat-sealed with a polyethylene non-woven fabric in a range of 105 to 135 ° C.
[12] The multilayer film according to any one of [1] to [11] and a polyethylene non-woven fabric are provided.
A package in which at least a part of the sealant layer of the multilayer film is heat-sealed on the surface of the non-woven fabric.
[13] The package according to [12], wherein the peel strength between the multilayer film and the non-woven fabric is 1.0 to 8.0 (N / 25 mm).

As described above, the multilayer film of the present invention includes at least a sealant layer provided so as to be a surface layer, and the sealant layer has a first resin having a melting point of at least 70 to 110 ° C. and 130 to 130 to Including a second resin having a melting point of 200 ° C., the melt flow rate (Melt Flow Rate; hereinafter also referred to as MFR) of the first resin is 3 g / 10 min or more, and in the sealant layer, the total of the sealant layers. Since the ratio of the content of the first resin to the mass is 51 to 99% and the ratio of the content of the second resin is 1 to 49%, the sealant layer reaches the end during extrusion film formation. Spreading and variation in thickness are suppressed, regions without a sealant layer (hereinafter, also referred to as “layer breakage”) are reduced on both ends in the width direction of the film, and yield is improved.

Since the package of the present invention is configured to include the multilayer film of the present invention, it has desired easy peelability with respect to a polyethylene non-woven fabric.

It is sectional drawing of the multilayer film which is one Embodiment to which this invention is applied. It is sectional drawing of the multilayer film which is one Embodiment to which this invention is applied. It is sectional drawing in the film width direction which showed the sea-island structure of the sealant layer of the multilayer film which is one Embodiment to which this invention applied the MFR of 3g / 10min or more. It is sectional drawing in the film width direction which showed the sea-island structure of the sealant layer of the multilayer film with MFR less than 3g / 10min.

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

<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 by including another resin layer laminated on the resin layer. The multilayer film 1 of the present embodiment can be used as a film for a bottom material of a packaging body, particularly a medical packaging body.

(Sealant layer)
The sealant layer 2 is a resin layer provided for bonding to a non-woven fabric or the like to be bonded by heat sealing and for imparting easy-opening property. The sealant layer 2 is composed of a first resin having a melting point of 70 to 110 ° C., preferably 75 to 110 ° C., more preferably 80 to 110 ° C., further preferably 85 to 105 ° C., and particularly preferably 85 to 100 ° C. It contains a second resin having a melting point of 130 to 200 ° C., preferably 140 to 170 ° C., more preferably 150 to 165 ° C. When the melting point of the first resin is equal to or higher than the lower limit of the above range, it does not become sticky even in a high temperature environment such as summer, and heat seals with a polyethylene non-woven fabric and an appropriate peel strength in the range of 105 to 135 ° C. Is possible. On the other hand, if it is not more than the upper limit of the above range, the polyethylene non-woven fabric can be sealed without melting during heat sealing.
Further, when the melting point of the second resin is at least the lower limit of the above range, softening of the second resin is suppressed at the time of sealing and the peel strength is stable, and when it is at least the upper limit of the above range, for example, a polyethylene non-woven fabric is used. After joining, it is possible to prevent the fibers of the polyethylene non-woven fabric from tearing when peeling.

In the present specification, the "melting point" means a measurement in accordance with JIS K-7121 as described in Examples described later, unless otherwise specified.

The sealant layer 2 has an MFR of 3 g / 10 min or more, preferably 3.5 g / 10 min or more, and more preferably 5 g / 10 min or more.
The MFR of the first resin of the sealant layer 2 is preferably 20 g / 10 min or less, more preferably 18 g / 10 min or less, particularly preferably 16 g / 10 min or less, and even more preferably 14 g / 10 min or less.
The MFR of the first resin of the sealant layer 2 is, for example, 3 to 20 g / 10 min, 3 to 18 g / 10 min, 3 to 15 g / 10 min, 3.5 to 20 g / 10 min, 3.5 to 18 g / 10 min, 3. 5 to 15 g / 10 min, 5 to 20 g / 10 min, 5 to 18 g / 10 min, 5 to 15 g / 10 min, and the like.
When the MFR of the first resin is not more than the lower limit of the above range, the sealant layer spreads to the edge of the film during extrusion of the multilayer film, the thickness does not vary, and the layers are formed on both ends in the width direction of the film. Cuts are reduced and yield is improved. Further, when the MFR of the first resin is not more than the upper limit value in the above range, the generation of adhered foreign matter on the molding hot plate is suppressed when molding the multilayer film, and equipment contamination due to the adhered foreign matter can be prevented. ..
MFR can be measured according to JIS K6922-1.

The first resin that can be used for the sealant layer 2 is not particularly limited as long as it is a resin having the above melting point and MFR, and examples thereof include polyethylene-based resins.

Examples of the polyethylene-based resin include homopolymers 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-acrylate 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 polyethylene-based resin preferably contains an ethylene homopolymer or an ethylene-based copolymer, and may contain both of them. The polyethylene-based resin is more preferably an ethylene homopolymer or an ethylene-based copolymer, and may be both of them.
The ethylene-based copolymer preferably contains an ethylene-vinyl acetate copolymer or an ethylene-acrylate copolymer, more preferably contains an ethylene-vinyl acetate copolymer, and is preferably an ethylene-vinyl acetate copolymer. More preferred.

The second resin that can be used for the sealant layer 2 is not particularly limited as long as it has the above melting point, and examples thereof include a resin that is polypropylene (PP) or polybutene (PB).

As polypropylene, homopolymers, random copolymers, block copolymers and the like are used alone or in admixture of two or more, and among them, homo-PP polymers are preferably used.

The content of the first resin constituting the sealant layer 2 is 51 to 99% by mass, preferably 65 to 95% by mass, and more preferably 75 to 95% by mass. When the content of the first resin constituting the sealant layer 2 is at least the above lower limit value, the first resin is present in the sea phase in the sealant layer 2.
Here, the content of the first resin constituting the sealant layer 2 means the ratio of the content of the first resin component to the total mass (100% by mass) of all the components constituting the sealant layer 2.

The content of the second resin constituting the sealant layer 2 is 1 to 49% by mass, preferably 5 to 35% by mass, and more preferably 5 to 25% by mass. When the content of the second resin constituting the sealant layer 2 is not more than the above upper limit value, the second resin is present in the island phase in the sealant layer 2.
Here, the content of the second resin constituting the sealant layer 2 means the ratio of the content of the second resin component to the total mass (100% by mass) of all the components constituting the sealant layer 2.

As a more preferable sealant layer 2, for example, a sealant layer 2 that satisfies both the above-mentioned contents of the first resin and the conditions of the content of the second resin can be mentioned. That is, in the multilayer film 1, the content of the first resin constituting the sealant layer 2 is 51 to 99% by mass, and the content of the second resin constituting the sealant layer 2 is 1 to 49% by mass; The content of the first resin constituting the sealant layer 2 is preferably 65 to 95% by mass, and the content of the second resin constituting the sealant layer 2 is preferably 5 to 35% by mass; It is more preferable that the content of the first resin to be used is 75 to 95% by mass, and the content of the second resin constituting the sealant layer 2 is 5 to 25% by mass.

The sealant layer 2 has a sea-island structure, and the second resin is present in the island phase, and the sealant layer is formed from a center line connecting the centers in the width direction of the sealant layer toward both ends in the width direction of the sealant layer. The region up to a distance of 10% with respect to the width is the central portion, and the region from both ends in the width direction of the sealant layer to the distance of 10% with respect to the width of the sealant layer is the end portion. , When viewed in a plan view from above the surface, the maximum value of the line segment connecting two points on the surface of the island fauna existing in the central portion is obtained, the average value L1 is calculated, and the end portion is described. When the maximum value of the line segment connecting two points on the surface of the island fauna existing in is calculated and the average value L2 is calculated, L1: L2 is preferably 1: 0.7 to 1: 1. , 1: 0.74 to 1: 1, more preferably 1: 0.76 to 1: 1.
Since L1: L2 is within the above range, as shown in FIG. 3, when the sealant layer is viewed in a plan view from above the surface of the sealant layer, the shape of the island facies at the end of the sealant layer is formed. However, it approaches the shape of the island facies in the central part, and it is possible to suppress the variation in the peel strength of the sealant layer. When the L1: L2 is less than 1: 0.7, as shown in FIG. 4, when the sealant layer is viewed in a plan view from above the surface thereof, the island phase at the edge of the multilayer film The shape of the island phase and the shape of the island phase at the center are different from each other, and the variation in the peel strength of the sealant layer becomes large.

When calculating the L1, the number of island phases for measuring the maximum value of the line segment connecting two points on the surface of the island phase existing in the central portion is preferably 10 to 50, for example, 40. There may be 30, 30 or 20.
Further, when calculating the L2, the number of island phases for measuring the maximum value of the line segment connecting two points on the surface of the island phase existing at the end is preferably 10 to 50, for example, 40. It may be 30 pieces, 30 pieces, or 20 pieces.

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, Yasuhara Chemical, "Hirodyne series") and the like.

The ratio of the thickness of the sealant layer 2 to all the layers of the multilayer film 1 is preferably 3 to 20%, more preferably 3 to 15%, still more preferably 5 to 15%. When the thickness ratio is equal to or higher than the above lower limit, a predetermined peeling strength can be obtained when heat-sealing with a polyethylene non-woven fabric, and peeling depends on heat-sealing time, heat-sealing temperature, heat-sealing pressure, and the like. Uneven strength is suppressed. Further, when the thickness ratio is not more than the upper limit value, the non-woven fabric is not torn when the non-woven fabric is peeled off even when heat-sealed with the polyethylene non-woven fabric at a high temperature of 130 ° C. or higher, and the fibers to the sealant layer are formed. Excellent peelability due to less adhesion.

The thickness of the sealant layer 2 is preferably 1 to 20 μm, more preferably 3 to 20 μm. When the above thickness is at least the lower limit of the preferable range, a predetermined peeling strength can be obtained when heat-sealing with a polyethylene non-woven fabric, and peeling depends on the heat-sealing time, heat-sealing temperature, heat-sealing pressure, and the like. Uneven strength is suppressed. Further, when the above thickness is not more than the upper limit value, even when heat-sealed with the polyethylene non-woven fabric at a high temperature of 130 ° C. or higher, the non-woven fabric does not tear when the non-woven fabric is peeled off, and the fibers adhere to the sealant layer. Excellent peelability due to the small amount.

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

Examples of the polyethylene-based resin include homopolymers 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. Polyethylene resin); ethylene-vinyl acetate copolymer (EVA) resin, ethylene-methyl methacrylate copolymer (EMMA) resin, ethylene-ethyl acrylate copolymer (EEA) resin, ethylene-methyl acrylate copolymer (EMA) Ethylene-based copolymers such as resins, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH) resins, ethylene-acrylate copolymer (EAA) resins, ethylene-methacrylic acid copolymer (EMAA) resins; Ionomer (ION) resin and the like are used alone or in combination of two or more.
As the polyethylene resin, the above LLDPE is preferable. By using the base material layer 3 containing LLDPE, stable peel strength can be obtained and reuse is easy.

The base material layer 3 may be only one layer, or may have 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 two or more base material layers include a base material layer having two layers of HDPE and LLDPE.

The ratio of the thickness of the base material layer 3 to all the layers of the multilayer film 1 is preferably 60 to 75%, more preferably 63 to 75%, further preferably 65 to 75%, and particularly preferably 65 to 70%. When the thickness ratio is equal to or higher than the lower limit value, flexibility can be imparted to the multilayer film 1. When the thickness ratio is not more than the above upper limit value, unevenness of peel strength depending on the heat seal time, heat seal temperature, heat seal pressure and the like is suppressed.

The thickness of the base material layer 3 is preferably 30 to 150 μm, more preferably 60 to 100 μm. When the thickness is not less than the lower limit value of the preferable range, flexibility is obtained, and when it is not more than the upper limit value, unevenness of peel strength depending on the heat seal time, heat seal temperature, heat seal pressure and the like is suppressed.

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 the 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, known adhesive olefin resins such as adhesive polypropylene resins and adhesive polyethylene resins are 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 the 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 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)
The multilayer film 1 of the present embodiment is appropriately known for the purpose of improving slipperiness as necessary in the sealant layer 2 and the base material layer 3 described above to prevent blocking or impart anti-fog property. May contain the additive of. Examples of the additive for improving slipperiness and preventing blocking include organic lubricants such as oleic acid amide and erucic acid amide; and inorganic lubricants such as silica, zeolite and calcium carbonate. Moreover, as an additive for the purpose of imparting anti-fog property, already known surfactants and the like can be mentioned.

<Manufacturing method of multilayer film>
Next, an example of the method for producing the multilayer film 1 described above 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.

Examples of the laminating method include 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. And those methods can be used in combination. Further, it may be laminated by a coating method.

<Packaging body>
Next, an example of a package using the above-mentioned multilayer film 1 will be described.
The package of the present embodiment includes the above-mentioned multilayer film and a polyethylene non-woven fabric, and at least a part of the sealant layer of the multilayer film is heat-sealed on the surface of the non-woven fabric.
Since the package of the present invention is configured to include the multilayer film of the present invention having stable peel strength while suppressing variation in the thickness of the sealant layer, the polyethylene non-woven fabric can be easily peeled from the multilayer film. ..

The polyethylene non-woven fabric applicable to the packaging of the present embodiment has characteristics that can be heat-sealed with the sealant layer, and that when the non-woven fabric is formed, it has breathability and prevents fungi from entering the container (prevention). It is not particularly limited as long as it can exhibit (bacterial). Examples of polyethylene (PE) constituting such a non-woven fabric include HDPE, LDPE, LLDPE and the like. Among these, HDPE is preferably used from the viewpoint of strength and heat sealability.

When the package of the present embodiment is used as a medical package, the polyethylene non-woven fabric preferably has small holes capable of exhibiting breathability and antibacterial properties. Specifically, it is preferably a non-woven fabric composed of fibers in the range of 0.0001 to 20 dtex and having a basis weight of 10 to 300 g / m ^2.

The package of the present embodiment can be used as a deep-draw package by deep-drawing the bottom material, filling it with contents such as gauze, covering it with a lid material, and heat-sealing it. In particular, when the above-mentioned multilayer film is used as the bottom material of the deep-drawn package and the polyethylene non-woven fabric is used as the lid material, a good deep-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 a polyethylene non-woven fabric used as a lid material by an adhesive means such as a heat seal. Specifically, it can be produced by heat sealing in a temperature range of 105 to 135 ° C. Further, in the package of the present embodiment, the peel strength between the multilayer film and the polyethylene non-woven fabric is preferably 1.0 to 8.0 (N / 25 mm), and 1.2 to 7.5 (N). / 25 mm) is more preferable, and 1.5 to 7.0 (N / 25 mm) is particularly preferable. When the above-mentioned peel strength is at least the lower limit of the above preferable range, the sealing property of the package is obtained, and when it is at least the upper limit, good openability, for example, fiber tearing and fluffing during peeling. Suppressive effect can be obtained.

The peel strength can be measured using a tensile tester (for example, manufactured by A & D Co., Ltd., TENSILON RTG-1310, etc.) in accordance with JIS Z0237.

As described above, according to the multilayer film of the present embodiment, at least a sealant layer provided so as to be a surface layer is provided, and the sealant layer is a first resin having a melting point of at least 70 to 110 ° C. , A second resin having a melting point of 130 to 200 ° C., the melt flow rate of the first resin is 3 g / 10 min or more, and in the sealant layer, the first resin with respect to the total mass of the sealant layer. Since the content ratio is 51 to 99% and the content ratio of the second resin is 1 to 49%, the variation in the thickness of the sealant layer is suppressed, and the variation in the thickness of the sealant layer is suppressed in the width direction of the film. Layer breakage is reduced on both ends, and yield is improved.
Further, the sealant layer has a sea-island structure, the second resin is present in the island phase, and the sealant is directed from the center line connecting the centers in the width direction of the sealant layer toward both ends in the width direction of the sealant layer. The region up to a distance of 10% with respect to the width of the layer is the central portion, and the region from both ends in the width direction of the sealant layer to the distance of 10% with respect to the width of the sealant layer is the end portion. When the layer is viewed in a plan view from above the surface, the maximum value of the line segment connecting the two points on the surface of the island fauna existing in the central portion is obtained, and the average value L1 is calculated. When the maximum value of the line segment connecting two points on the surface of the island fauna existing at the end is obtained and the average value L2 is calculated, L1: L2 is 1: 0.7 to 1: 1. According to the multilayer film of the present embodiment, the shape of the island phase at the edge portion approaches the shape of the island phase at the central portion, and the variation in the peeling strength of the sealant layer can be suppressed.

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, 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 property 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 composed 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. 2 was produced by the following procedure.
First, as a resin contained in the pinhole-resistant layer, 6-nylon (Ny) (manufactured by Ube Industries, Ltd., product number: 1022B) was prepared.
Further, as a 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.
Further, as a resin contained in the base material layer, a linear low density polyethylene (LLDPE) resin (manufactured by Dow Co., Ltd., product number: Elite 5220G) was prepared.
Further, as the resin contained in the sealant layer, an ethylene-vinyl acetate copolymer (EVA) resin having a melting point of 88 ° C. and an MFR of 3.5 g / 10 min (manufactured by Mitsui / Dow Polychemical Co., Ltd., product number: Evaflex EV560) and a melting point are used. Homopropylene (manufactured by Prime Polymer Co., Ltd., product number: Y-400GP) at 160 ° C. was prepared and kneaded at a ratio of 85:15.
Next, a multilayer film having a four-layer structure in the order of pinhole-resistant layer / adhesive layer / base material layer / sealant layer was produced by extrusion processing. The width of the film was 2580 mm. The thickness of the pinhole-resistant layer of the obtained film was 15 μm, the thickness of the adhesive layer was 8 μm, the thickness of the base material layer was 66 μm, the thickness of the sealant layer was 11 μm, and the total thickness was 100 μm. The ratio of the thickness of the base material layer to all layers is 66%, and the ratio of the thickness of the sealant layer to all layers is 11%.
The melting point of each resin was measured using differential scanning calorimetry (DSC6220 manufactured by SII) based on JIS K-7121. In a nitrogen atmosphere, the temperature is raised from 25 ° C. to 180 ° C. at a rate of 2 ° C./min, cooled to −40 ° C. at a rate of 50 ° C./min, and then raised again to 180 ° C. at a rate of 2 ° C./min, 2 The melting point at the time of the second temperature rise was measured. When two or more melting point peaks were detected, the high temperature side was taken as the melting point. The same applies below.

(Example 2)
As the resin contained in the sealant layer, instead of the ethylene-vinyl acetate copolymer (EVA) resin having a melting point of 88 ° C. and an MFR of 3.5 g / 10 min (manufactured by Mitsui / Dow Polychemical Co., Ltd., product number: Evaflex EV560), the melting point Withstands the same as in Example 1 except that an ethylene-vinyl acetate copolymer (EVA) resin (manufactured by Mitsui / Dow Polychemical Co., Ltd., product number: Evaflex P1007) at 88 ° C. and MFR 9.0 g / 10 min is used. A multilayer film having a four-layer structure in the order of pinhole layer / adhesive layer / base material layer / sealant layer was produced by extrusion processing.

(Example 3)
As the resin contained in the sealant layer, instead of the ethylene-vinyl acetate copolymer (EVA) resin having a melting point of 88 ° C. and an MFR of 3.5 g / 10 min (manufactured by Mitsui / Dow Polychemical Co., Ltd., product number: Evaflex EV560), the melting point Withstands the same as in Example 1 except that an ethylene-vinyl acetate copolymer (EVA) resin (manufactured by Mitsui / Dow Polychemical Co., Ltd., product number: Evaflex EV250) at 88 ° C. and MFR 15.0 g / 10 min is used. A multilayer film having a four-layer structure in the order of pinhole layer / adhesive layer / base material layer / sealant layer was produced by extrusion processing.

(Comparative Example 1)
As the resin contained in the sealant layer, instead of the ethylene-vinyl acetate copolymer (EVA) resin having a melting point of 88 ° C. and an MFR of 3.5 g / 10 min (manufactured by Mitsui / Dow Polychemical Co., Ltd., product number: Evaflex EV560), the melting point Withstands the same as in Example 1 except that an ethylene-vinyl acetate copolymer (EVA) resin (manufactured by Mitsui / Dow Polychemical Co., Ltd., product number: Evaflex V5714C) at 88 ° C. and MFR 2.7 g / 10 min is used. A multilayer film having a four-layer structure in the order of pinhole layer / adhesive layer / base material layer / sealant layer was produced by extrusion processing.

<Evaluation method>
The multilayer films obtained in Examples and Comparative Examples and a medical packaging material (manufactured by DuPont, "Tyvek (registered trademark) 40L") are laminated so that the Tyvek side is on the hot plate side, and Teflon (registered trademark) is used. ) After placing the sheet, it was sealed under the following conditions using an auto cup sealer. The peeling direction was evaluated by peeling the film in the MD direction.
-Seal pressure: 11.2 kgf / cm ² (1.1 MPa)
-Seal time: 3.5 seconds-Seal temperature: 100, 110, 120, 130 ° C (4 conditions at 10 ° C intervals)

For all the evaluation samples of the packaging bodies obtained in Examples and Comparative Examples, evaluation of heat sealability, evaluation of hot plate adhesion, evaluation of thickness variation, evaluation of layer breakage length, and evaluation of island phase shape of sea-island structure were performed. went.

(Evaluation of heat sealability 1)
(Peeling strength)
The peel strength was evaluated by measuring the peel strength at a seal width of 25 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 peel strength of the evaluation samples prepared at each seal temperature for Examples and Comparative Examples.

(Removability)
The peelability was evaluated by peeling off the lid material and the bottom material of the package as the evaluation sample.
The evaluation was carried out by observing the peeled surfaces of the lid material and the bottom material after peeling and judging according to the following criteria. Table 1 shows the evaluation results of the peelability of the evaluation samples prepared at each seal temperature for Examples and Comparative Examples.
Judgment A: The lid material is not torn and the bottom material is not adhered with fibers. Judgment B: The lid material is torn or the bottom material is adhered with fibers.

(Evaluation of heat sealability 2)
In the evaluation 2 of heat-sealing property, the medical packaging material was "Tyvek (registered trademark) 1073B" manufactured by DuPont Co., Ltd., the sealing temperature was only 130 ° C., and the medical packaging material was sealed at each of the central portion and the end portion. , The peeling strength of the central part and the end part when the lid material and the bottom material of the package, which is the evaluation sample prepared by the method described in <Evaluation method>, are peeled off and peeled off, and the central part and the end part. This was done by evaluating the peelability of the product.
The peelability was evaluated by observing the peeled surfaces of the lid material and the bottom material after peeling at the central portion and the end portion, respectively, and judging according to the following criteria. Table 2 shows the evaluation results of the peel strength and the peelability of the evaluation sample prepared at 130 ° C. for Examples and Comparative Examples.
Judgment A: The lid material is not torn and the bottom material is not adhered with fibers. Judgment B: The lid material is torn or the bottom material is adhered with fibers.

(Evaluation of hot plate adhesion)
For the evaluation of hot plate adhesion, GEA PowerPak ST 420 was used, and after cleaning the hot plate with alcohol, the hot plate surface was operated for 7 hours under the conditions of a molding temperature of 108 ° C., a heating time of 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.

(Evaluation of thickness variation)
The thickness variation of the sealant layer was evaluated for the multilayer films of Examples and Comparative Examples.
The evaluation was performed by measuring the thickness of the cross section at 5 points when cutting at an angle of 90 ° in the flow direction and calculating the difference between the maximum value and the minimum value. The results are shown in Table 1.

(Evaluation of layer break length)
For the multilayer films of Examples and Comparative Examples, the length of the region without the sealant layer in the width direction was measured on both ends in the width direction of the multilayer film, and this was taken as the layer break length. The results are shown in Table 1.

(Evaluation of the shape of the island fauna of the sea island structure)
For the multilayer films of Examples and Comparative Examples, a region from the center line connecting the centers in the width direction of the sealant layer to both ends in the width direction of the sealant layer up to a distance of 10% with respect to the width of the sealant layer. Is the central portion, and the region from both ends in the width direction of the sealant layer to a distance of 10% with respect to the width of the sealant layer is the end portion, and the sealant layer is viewed in a plan view from above the surface thereof. Occasionally, the maximum value of the line segment connecting two points on the surface of the 20 island fauna existing in the central portion is obtained, the average value L1 is calculated, and the 20 island fauna existing at the end portion is calculated. The maximum value of the line segment connecting the two points on the surface of the surface was obtained, and the average value L2 was calculated. The results are shown in Table 1.

As shown in Table 1, in Examples 1 to 3, the sealant layer of the multilayer film used as the bottom material has a first resin having a melting point of 80 to 110 ° C. and a second resin having a melting point of 130 to 200 ° C. The MFR of the first resin is 3 g / 10 min or more, and the ratio of the content of the first resin to the total mass of the sealant layer in the sealant layer is 85%. Since the content ratio of the second resin is 15%, the layer cut length of the sealant layer is 54 mm or less, the sealant layer extends to the edge of the film, and the yield is improved. Further, in all the evaluation samples having a sealing temperature of 100 to 130 ° C., the lid material is not torn when peeled, and the fibers are less adhered to the bottom material, so that the peelability is excellent even when heat-sealed at a high temperature. It was confirmed that there was. Moreover, the thickness variation of the sealant layer was small.
Further, as shown in Table 2, in Examples 1 to 3, since L1: L2 is 1: 0.7 to 1: 1, the difference in peel strength between the central portion and the end portion is small, and the central portion and the edge are small. There was no tearing of the bottom material or adhesion of fibers to the bottom material.

On the other hand, in Comparative Example 1, since the MFR of the first resin was less than 3 g / 10 min, the layer cut length of the sealant layer was 95 mm or more, the sealant layer did not spread to the edge of the film, and the yield was poor. In addition, the thickness of the sealant layer varied widely.
Further, as shown in Table 2, in Comparative Example 1, since L1: L2 is less than 1: 0.7, the difference in peel strength between the central portion and the end portion is large, and the bottom material is torn or the bottom is torn at the end portion. Fiber adhesion to the material occurred.

By suppressing the variation in the thickness of the sealant layer and reducing the layer breakage, the yield is improved, and further, the variation in the peeling strength of the sealant layer is suppressed, which is desired for the multilayer film and the non-woven fabric made of polyethylene. It is possible to provide a package having peelability.

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 10 ... Island phase 20 ... Sea phase

Claims (13)

At least a sealant layer provided to be a surface layer is provided.
The sealant layer contains a first resin having a melting point of at least 70 to 110 ° C. and a second resin having a melting point of 130 to 200 ° C.
The melt flow rate of the first resin is 3 g / 10 min or more, and the melt flow rate is 3 g / 10 min or more.
In the sealant layer, the ratio of the content of the first resin to the total mass of the sealant layer is 51 to 99%, and the ratio of the content of the second resin is 1 to 49%. the film. The sealant layer has a sea-island structure, the second resin is present in the island phase, and the sealant layer is formed from a center line connecting the centers in the width direction of the sealant layer toward both ends in the width direction of the sealant layer. The region up to a distance of 10% with respect to the width is the central portion, and the region from both ends in the width direction of the sealant layer to the distance of 10% with respect to the width of the sealant layer is the end portion. , When viewed in a plan view from above the surface, the maximum value of the line segment connecting two points on the surface of the island fauna existing in the central portion is obtained, the average value L1 is calculated, and the end portion is described. The claim that L1: L2 is 1: 0.7 to 1: 1 when the maximum value of the line segment connecting two points on the surface of the island fauna existing in is calculated and the average value L2 is calculated. The multilayer film according to 1. The multilayer film according to claim 1 or 2, wherein the first resin contains a polyethylene-based resin. The multilayer film according to claim 3, wherein the polyethylene-based resin contains at least one selected from the group consisting of an ethylene homopolymer and an ethylene-based copolymer. The multilayer film according to any one of claims 1 to 4, wherein the second resin contains polypropylene. The multilayer film according to claim 4 or 5, wherein the ethylene-based copolymer contains an ethylene-vinyl acetate copolymer. The multilayer film according to claim 5 or 6, wherein the polypropylene contains homopolypropylene. The multilayer film according to any one of claims 1 to 7, which is provided adjacent to the sealant layer and includes a base material layer containing a polyethylene-based resin. The multilayer film according to claim 8, wherein the base material layer contains a linear low-density polyethylene resin. The multilayer film according to claim 8 or 9, wherein the ratio of the thickness of the sealant layer to the base material layer is in the range of 1: 4 to 1:12. The multilayer film according to any one of claims 1 to 10, wherein the multilayer film can be heat-sealed with a polyethylene non-woven fabric in a range of 105 to 135 ° C. The multilayer film according to any one of claims 1 to 11 and a polyethylene non-woven fabric are provided.
A package in which at least a part of the sealant layer of the multilayer film is heat-sealed on the surface of the non-woven fabric. The package according to claim 12, wherein the peel strength between the multilayer film and the non-woven fabric is 1.0 to 8.0 (N / 25 mm).

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