JP2021104675A - Laminate and container - Google Patents

Abstract

To provide a laminate and a container which have excellent interlayer bonding strength and have a tendency that the bonding strength is less likely to degrade even in a high-temperature sterilization treatment or the like.SOLUTION: A laminate includes at least three layers of a cyclic olefin-based resin, an adhesive layer and a polypropylene resin layer which are laminated one upon another in this order. Resin components included in the adhesive layer are substantially formed by three components of linear low-density polyethylene, styrenic elastomer and polypropylene resin.SELECTED DRAWING: None

Description

The present invention relates to laminates and containers.

In recent years, as a preparation for intravenous drip infusion, a premix type soft bag preparation in which a premixed injection drug having been diluted and prepared is filled in a container molded of a plastic resin or the like has been developed. Compared with the case where the concentrated drug is filled in a glass container such as a bottle or an ampoule, this type of preparation is excellent in the convenience and quickness of using the drug as well as the disposability of the container.

However, when a general resin such as polyolefin (polyethylene, polypropylene) or polyvinyl chloride is used as a container material for a soft bag formulation, some drugs such as nitroglycerin, albumin, vitamins, trace elements, and radical scavengers are used. Is known to adsorb or permeate. Therefore, a container having a cyclic olefin resin layer as a material having no drug adsorptivity and permeability is useful for a container for a soft bag formulation (for example, Patent Documents 1 and 2).

Since the cyclic olefin resin forms a high-density and three-dimensional molecular structure as compared with polyethylene and the like, when the cyclic olefin resin is formed into a sheet by itself, it tends to be a hard and brittle sheet. Therefore, in order to process it into a soft bag, it is common to laminate a polyethylene-based resin, a polypropylene-based resin, or the like.

On the other hand, the cyclic olefin resin has a problem that it is difficult to obtain adhesive strength with other materials. As a means for solving this, a method has been proposed in which an adhesive layer containing a linear low-density polyethylene resin polymerized using a single-site catalyst as a main component is provided adjacent to the cyclic olefin resin layer ( For example, Patent Document 3).

For example, Patent Document 3 proposes a laminated sheet in which the innermost layer is a cyclic olefin resin, the intermediate layer is a linear low-density polyethylene resin polymerized using a single-site catalyst, and the outermost layer is high-density polyethylene. There is. In this configuration, high-density polyethylene, which is excellent in adhesive stability between layers but generally lacks flexibility and transparency, is used. Therefore, if the thickness of the outermost layer is increased in order to ensure heat resistance, the visibility and dischargeability of the contents are impaired, and there is a drawback that the performance required for the pharmaceutical container is not satisfied. Further, since high-density polyethylene has a low melting point of about 120 ° C., if heat treatment or sterilization treatment is performed at a higher temperature than that, there is a possibility that the container may be deformed.

It is common to use a polypropylene-based resin having a melting point higher than that of polyethylene as a means for imparting heat resistance to the container, but it has been difficult in the past to firmly bond the polypropylene-based resin layer and the cyclic olefin-based resin layer. rice field. In order to solve this problem, for example, Patent Document 4 describes a linear low-density polyethylene resin polymerized using a single-site catalyst as an adhesive layer between a cyclic polyolefin resin layer and a polypropylene-based resin layer. , A composition in which a polypropylene-based resin is blended has been proposed.
In Patent Document 5, although it has a two-layer structure, a multilayer container in which the polypropylene-based resin layer adjacent to the cyclic olefin-based resin layer contains a styrene-based elastomer is proposed.

Japanese Unexamined Patent Publication No. 2008-29829 International Publication No. 2009/66752 Japanese Unexamined Patent Publication No. 2008-18603 Japanese Unexamined Patent Publication No. 2005-335108 Japanese Unexamined Patent Publication No. 2011-93209

However, in the laminate described in Patent Document 4, since the polyethylene-based resin is used for the adhesive layer, the adhesive strength may decrease at a temperature higher than the melting point of the polyethylene-based resin. In addition, the initial adhesive strength of the adhesive layer is not sufficient, and when the container filled with the contents is dropped, the seal interface may be peeled off or liquid leakage may occur.

Further, Patent Document 2 described above proposes a container in which a resin composition layer composed of a blend of a propylene-based polymer and a styrene-based elastomer is laminated between a cyclic olefin-based resin layer and a polypropylene-based resin layer. ing. However, in this configuration, when an organic solvent such as alcohol or ethyl acetate adheres to the bonding interface, the interlayer bonding strength is greatly reduced, and further delamination may occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laminate and a container which are excellent in adhesive strength between layers and whose adhesive strength does not easily decrease even in a high-temperature sterilization treatment or the like.

In order to solve the above problems, the present invention is a laminated body having at least three or more layers including a structure in which a cyclic olefin resin layer, an adhesive layer, and a polypropylene resin layer are laminated in this order. The adhesive layer contains a resin component composed of linear low-density polyethylene, styrene-based elastomer, and polypropylene-based resin, and the ratio of (linear low-density polyethylene): (total of styrene-based elastomer and polypropylene-based resin) is Provided is a laminate characterized in that the weight ratio is in the range of 40:60 to 95: 5.

The ratio of (styrene-based elastomer): (polypropylene-based resin) in the adhesive layer is preferably in the range of 5:95 to 50:50 as a weight ratio.
It is preferable that the styrene-based elastomer is at least one selected from SEBS, SEPS, SEBC, and HSBR.
The styrene-based elastomer is preferably SEBS.
The styrene content in the styrene-based elastomer is preferably 10 to 50% by weight.
It is preferable that the polypropylene-based resin contained in the adhesive layer is a propylene-based copolymer in which at least one or more of ethylene or α-olefin having 4 to 8 carbon atoms is copolymerized.

The present invention also provides a container formed by using the laminated body.

According to the present invention, it is possible to provide a laminate and a container which are excellent in adhesive strength between layers and whose adhesive strength does not easily decrease even in a high temperature sterilization treatment or the like.

Hereinafter, the present invention will be described based on preferred embodiments.

The laminate of the present embodiment is a laminate of at least three or more layers including a structure in which a cyclic olefin resin layer, an adhesive layer, and a polypropylene resin layer are laminated in this order. The adhesive layer is an intermediate layer for adhering between the cyclic olefin resin layer and the polypropylene resin layer.

The adhesive layer contains linear low-density polyethylene, a styrene-based elastomer, and a polypropylene-based resin. The resin component contained in the adhesive layer may be substantially composed of three components of linear low-density polyethylene, a styrene-based elastomer, and a polypropylene-based resin. The adhesive layer may contain an additive component in addition to the resin component.

Linear low-density polyethylene (LLDPE) usually has a linear molecular structure with few long-chain branches by copolymerizing an α-olefin having 4 or more carbon atoms and introducing short-chain branches. Have. Examples of the α-olefin copolymerized with LLDPE include 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like.

Examples of the type of LLDPE contained in the adhesive layer include a resin polymerized using a Ziegler-Natta catalyst, a resin polymerized using a single-site catalyst, and the like. LLDPE polymerized using a single-site catalyst is preferable because it has a narrow molecular weight distribution and excellent mechanical properties. Examples of the single-site catalyst include metallocene catalysts. Examples of the metallocene-based catalyst include catalysts containing a ligand having a cyclopentadienyl skeleton and containing a metallocene compound whose metal is zirconium, hafnium or the like.

As the polypropylene-based resin contained in the adhesive layer, a propylene-based copolymer in which at least one or more of ethylene or α-olefin having 4 to 8 carbon atoms is copolymerized is preferable, and among them, polymerization is carried out using a single-site catalyst. The propylene-based copolymer obtained is preferable. Examples of the comonomer copolymerized with the polypropylene resin include ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. The polypropylene-based resin contained in the adhesive layer may be a random copolymer or a block copolymer.

Examples of the styrene-based elastomer contained in the adhesive layer include a copolymer of styrene and an aliphatic olefin. A block containing styrene constitutes a hard block, and a block containing an aliphatic olefin constitutes a soft block. The higher the styrene content in the molecule, the stronger the adhesive strength can be exhibited. However, if the styrene content is too high, the flexibility is impaired. Therefore, the styrene content in the styrene-based elastomer is preferably 10 to 50% by weight, more preferably 10 to 30% by weight, and further preferably 10 to 20% by weight. preferable.

Specific examples of the styrene-based elastomer include styrene-ethylene copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-ethylene-propylene-styrene block copolymer (SEPS), and styrene-ethylene-butylene. -Styrene block copolymer (SEBS), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isoprene-butadiene-styrene block copolymer (SIBS) , Styrene-ethylene-butylene-olefin crystal block copolymer (SEBC), hydrogenated styrene-butadiene rubber (HSBR), and the like. Among these, one or more selected from SEBS, SEPS, SEBC, and HSBR are preferable, and SEBS is particularly preferable.
SEBS is generally obtained by hydrogenating (hydrogenating) a styrene-butadiene-styrene block copolymer to convert a butadiene unit into two ethylene units or a butylene unit, but it is modified. Or selective hydrogenation or the like.

The ratio of (linear low-density polyethylene): (total of styrene-based elastomer and polypropylene-based resin) in the adhesive layer is preferably in the range of 40:60 to 95: 5 as a weight ratio. Further, the ratio of (styrene-based elastomer): (polypropylene-based resin) in the adhesive layer is preferably in the range of 5:95 to 50:50 as a weight ratio.

The ratio of the linear low-density polyethylene, the styrene elastomer, and the polypropylene-based resin among the resin components constituting the adhesive layer is, for example, 100 parts by weight of the entire resin component, and 40 to 95 parts by weight of the linear low-density polyethylene. The ratio of styrene-based elastomer to 1 to 50 parts by weight and polypropylene-based resin to 1 to 59 parts by weight can be mentioned.
Here, the ratio of linear low-density polyethylene is more preferably 40 to 80 parts by weight.
Further, the ratio of 1 to 30 parts by weight of the styrene-based elastomer is more preferable.
Further, the proportion of polypropylene-based resin in an amount of 30 to 50 parts by weight is more preferable.

In the adhesive layer, the total of the three components of the linear low-density polyethylene, the styrene-based elastomer, and the polypropylene-based resin is preferably 90% by weight or more, more preferably 95% by weight or more, and may be 100% by weight. The adhesive layer may contain a resin component or an additive component other than the above three components, but the proportion thereof is preferably 10% by weight or less, more preferably 5% by weight or less of the entire adhesive layer.

The polypropylene-based resin layer is a layer mainly containing a polypropylene (PP) -based resin. The polypropylene-based resin used for the polypropylene-based resin layer may be a homopolymer of propylene, or a copolymer with ethylene or at least one or more α-olefins having 4 to 8 carbon atoms. May be good. When the polypropylene-based resin contained in the polypropylene-based resin layer is a copolymer, the copolymer may be a random copolymer or a block copolymer. The polypropylene-based resin layer may contain one kind of polypropylene-based resin, or may contain two or more kinds of polypropylene-based resin layers.

The cyclic olefin resin layer is a layer mainly containing a cyclic olefin resin. The cyclic olefin resin contained in the cyclic olefin resin is a polymer composed of one or more kinds of olefin monomers or a polymer in which a double bond thereof is hydrogenated, and at least one kind of the olefin monomer is cyclic carbonized. It is a cyclic olefin monomer having a hydrogen skeleton. Examples of the cyclic olefin monomer include norbornene compounds and the like.
In the following description, the term "cyclic olefin resin" simply refers to the cyclic olefin resin contained in the cyclic olefin resin.

The cyclic olefin resin is a polymer obtained by hydrogenating the remaining double bond after ring-opening metathesis polymerization of the norbornene compound, an addition polymer composed of two or more kinds of cyclic olefin monomers, a cyclic olefin monomer and a non-cyclic olefin monomer. Includes addition polymers obtained by copolymerizing the above. However, a homoadditive polymer containing only one cyclic olefin monomer is not preferable.
Examples of the method for producing the cyclic olefin resin include a method of hydrogenating a ring-opening metathesis polymer of a norbornene compound, a method of copolymerizing two or more kinds of cyclic olefin monomers, and a method of copolymerizing a cyclic olefin monomer and α-olefin. The method can be mentioned.

Among the cyclic olefin resins, for example, the following formula (I) can be mentioned as a basic structure of a polymer obtained by hydrogenating a ring-opening metathesis polymer of a norbornene compound. That is, in the formula (I), it is described as a polymer in which a cyclic skeleton and an ethylene skeleton are alternately arranged. The cyclic skeleton of the formula (1) is a 1,3-cyclopentylene skeleton. However, the ring-opening metathesis polymer itself of the norbornene compound does not have to be a copolymer.

In formula (I), n is an integer greater than or equal to 1, and R ¹ and R ² represent a hydrogen atom or an alkyl group. R ¹ and R ² may be the same or different from each other. R ¹ and R ² may be combined with each other to form a ring.

Formula structure shown in (I) are the same n number of 1,3-cyclopentylene substituents R ¹ and R ² have the skeleton to each other, ring-opening metathesis polymer of a norbornene compound homopolymer (homopolymer) It is not limited to the case of. The structure represented by the formula (I) may be a polymer obtained by hydrogenating a ring-opening metathesis polymer of two or more kinds of norbornene compounds. An example thereof is the following formula (II).

In formula (II), m and n are integers greater than or equal to 1, and R ¹ and R ² represent hydrogen atoms or alkyl groups. m and n may be the same or different from each other. R ¹ and R ² may be the same or different from each other. R ¹ and R ² may be combined with each other to form a ring.

Specific examples of the hydrogenated polymer of the ring-opening metathesis polymer of the norbornene compound include "ZEONEX (registered trademark)" and "ZEONOR (registered trademark)" manufactured by Nippon Zeon Corporation.

Further, as an addition polymer obtained by copolymerizing a cyclic olefin monomer and a non-cyclic olefin monomer, the following formula (III) can be mentioned. The copolymer of formula (III) is described as a polymer in which a cyclic skeleton and an ethylene skeleton are randomly arranged. The cyclic skeleton of formula (I1I) is a 2,3-norbornanilen skeleton.

In formula (III), m and n are integers of 1 or more, and R ¹ , R ² and R ³ represent a hydrogen atom or an alkyl group. m and n may be the same or different from each other. R ¹ , R ² and R ³ may be the same or different from each other. R ¹ and R ² may be combined with each other to form a ring.

Here, ^{as a polymer in which R 1} , R ² , and R ³ are all hydrogen atoms, "TOPAS (registered trademark)" manufactured by Polyplastics Co., Ltd. can be mentioned. Further, R ¹ and R2 is an alkyl group, as the polymer R ³ is a hydrogen atom, and manufactured by Mitsui Chemicals, Inc. "APEL (registered trademark)".

These cyclic olefin resins have excellent water vapor barrier properties and are easily available. As described above, in the laminate of the present embodiment, these cyclic olefin resins can be used as the main component of the cyclic olefin resin layer. The cyclic olefin-based resin layer may contain one kind of cyclic olefin-based resin, or may contain two or more kinds of cyclic olefin-based resins. Here, the two or more kinds of cyclic olefin-based resins may be two or more kinds of cyclic olefin-based resins corresponding to any one of the formulas (I) to (III), and the formulas (I) to (III). ), Each of the two or more formulas may contain one or more cyclic olefin resins, and may further contain cyclic olefin resins that do not fall under the formulas (I) to (III). Further, the cyclic olefin resin layer may be the innermost layer (sealant layer) in the laminated body.

Next, a commercially available product of the cyclic olefin resin will be illustrated. Although some overlap with the above, for example, ZEONEX (registered trademark) (manufactured by Nippon Zeon Co., Ltd., hydride polymer of ring-opening metathesis polymer of norbornene-based monomer), TOPAS (registered trademark) (manufactured by Polyplastics Co., Ltd.) , Norbornene and ethylene copolymer), ZEONOR (registered trademark) (manufactured by Nippon Zeon Co., Ltd., copolymer based on ring-opening polymerization of dicyclopentadiene and tetracyclopentadodecene), Apel (registered trademark) (Mitsui Chemicals, Inc.) , Copolymer of ethylene and tetracyclododecene), Arton (registered trademark) (manufactured by JSR Co., Ltd., cyclic olefin resin containing polar groups made from dicyclopentadiene and methacrylic acid ester) and the like.

The cyclic olefin-based resin layer may contain other resin components in addition to the cyclic olefin-based resin. Other resin components that may be contained in the cyclic olefin resin include polyethylene, polypropylene, polybutene, ethylene / α-olefin copolymer, ethylene / (meth) acrylic acid copolymer, and ethylene / vinyl acetate copolymer. , Polyethylene resin such as ethylene / (meth) acrylic acid ester copolymer, urethane resin, rubber resin, polyester resin, polyester urethane resin, acrylic resin, amide resin, styrene resin, silane resin One kind or two or more kinds such as. Among these, examples of the styrene-based resin include polystyrene, styrene-acrylonitrile copolymer (SAN), and styrene-based elastomer. Among them, in particular, styrene-butadiene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene block copolymers, styrene-isoprene styrene block copolymers, hydrogenated products thereof (for example, SEBS, SEPS, etc.), styrene-butadiene random It is preferable that one or more of the block polymers and the like are contained in the cyclic olefin resin layer in the range of 0.05 to 20% by mass.
When other resin components are contained, it is possible to improve the desired performance of the container, such as impact resistance at low temperature of the container, maintenance of transparency immediately after the high-pressure steam sterilization treatment, and improvement of flexibility.

The cyclic olefin-based resin layer preferably contains only the cyclic olefin-based resin as a resin component (an additive other than the resin may be contained), and may contain 100% by mass of the cyclic olefin-based resin (other additives may also be contained). Not included). When the other resin components described above are contained, the cyclic olefin resin layer contains the cyclic olefin resin as a main component, that is, 50% by mass in total of one cyclic olefin resin or two or more cyclic olefin resins. It is preferably contained in an amount of 70% by mass or more, and particularly preferably in an amount of 70% by mass or more. When the composition ratio of the cyclic olefin resin is low, trace components and drug components having a high affinity for plastics may be adsorbed, and the storage stability of the contained drug components may be insufficient.

In order to improve the appearance of the container, stabilize the quality, and impart other required performance to the materials constituting each layer constituting the laminate, that is, the polypropylene-based resin layer, the adhesive layer, the cyclic olefin-based resin layer, and the like. As long as safety and health are not impaired, various additives such as antioxidants, ultraviolet absorbers, antistatic agents, lubricants and antiblocking agents may be contained.

The method for molding each layer (film) used for the laminate (sheet) of the present embodiment is not particularly limited, and examples thereof include T-die molding and inflation molding. After the T-die molding, the film, sheet, etc. may be rapidly cooled with a cooling roll. When continuously molding a long film, sheet or the like, it is preferable to wind the long molded body such as the film or sheet after molding because the productivity is excellent.

An example of the laminated body is a structure in which a base material, a sealant layer, and, if necessary, another layer are laminated. That is, each layer may have an adhesive layer or an anchoring agent layer interposed therebetween, or may be laminated so that the layers are in direct contact with each other. As the other layer, one layer or a plurality of layers can be appropriately selected, such as a reinforcing layer, a gas barrier layer, a light-shielding layer, and a printing layer. The sealant layer is a layer used for heat sealing, and is arranged in the innermost layer in contact with the contents as a packaging material. The heat seal is a method of adhering by melting the sealant layer, but the sealing method is not particularly limited, and examples thereof include a hot plate seal, an ultrasonic seal, a high frequency seal, and an impulse seal. The base material may be the outermost surface of the other side of the laminate opposite to the sealant layer, or may be laminated inside the other outermost surface.

The method for producing the laminate of the present embodiment is not particularly limited, and each layer constituting the laminate can be obtained by using an extrusion laminating method, a dry laminating method, a coextrusion method, or a combination of two or more of these methods. It may be laminated as appropriate. The thickness of the sealant layer depends on the use of the packaging material and is not particularly limited, but is usually about 5 to 150 μm, preferably 15 to 80 μm. The thickness of the adhesive layer is not particularly limited, but is, for example, 10 to 100 μm.

When three layers of the cyclic olefin resin layer, the adhesive layer, and the polypropylene resin layer are laminated by the coextrusion method, the layers are laminated without the adhesive layer or the anchoring agent layer. Will be done. The laminate may include five layers of a cyclic olefin resin layer / adhesive layer / polypropylene resin layer / adhesive layer / cyclic olefin resin layer, and may include a polypropylene resin layer / adhesive layer / cyclic olefin resin layer / adhesive layer. / 5 layers of polypropylene resin layer may be included.

According to the laminate of the present embodiment, the interlayer strength between the cyclic olefin resin layer and the adhesive layer and the interlayer strength between the polypropylene resin layer and the adhesive layer can be significantly improved.
Further, the laminate of the present embodiment has high heat resistance as compared with the laminate composed of the polyethylene-based resin layer and the cyclic olefin-based resin layer. Therefore, it has heat resistance even at a high temperature exceeding 120 ° C., and high-pressure steam sterilization is also possible.
Further, the laminate of the present embodiment has higher heat resistance than the laminate composed of a polypropylene-based resin layer and a cyclic olefin-based resin layer, and has a peel strength even when high-pressure steam sterilization is performed. The decrease is suppressed, and the impact resistance of the container can be improved.

The container of the present embodiment can be formed by using the laminated body of the present embodiment. Examples of the container include a packaging bag (pouch), tube packaging, and the like. When the packaging bag is provided with a spout, the spout can be preferably used as long as it can be joined to the sealant layer of the laminate constituting the packaging bag to ensure hermeticity. Preferably, it is desirable to heat-seal the spout and the laminate using a sealant layer of the laminate and a spout made of a heat-sealable resin. When heat-sealing the laminate and the spout, the spout may be inserted between the laminates with the sealant layer on the inside to heat-seal, or a flange or boat-shaped fusion may be performed at one end of the spout. A base portion may be provided, and the flange portion or the fusion base portion may be heat-sealed with the peripheral edge of a hole provided in the laminate or the inner surface of the opening of the packaging bag.

The container of the present embodiment can be suitably used as a container for accommodating drugs, foods and drinks, cosmetics and the like. The drug may be a substance having high adsorptivity or permeability to general resins such as nitroglycerin, albumin, vitamins, trace elements, and radical scavengers.
The form of the packaging bag is a small packaging bag (pouch) such as a three-sided bag, a four-sided bag, a gassho-pasted bag, a gusset bag, or a self-standing bag, as well as a large bag such as an inner bag for a bag-in-box or an interior bag for a drum can. , It can be applied without particular limitation.

Although the present invention has been described above based on preferred embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

Hereinafter, the present invention will be specifically described with reference to Examples.

(Manufacturing method of laminated body)
Using a T-die type multilayer film forming machine, a laminated body was produced by a coextrusion method so that the thickness of the surface layer / intermediate layer / innermost layer was 180 μm / 50 μm / 30 μm, respectively.
For the surface layer, a polypropylene-based thermoplastic elastomer "Zeras (registered trademark)" (manufactured by Mitsubishi Chemical Corporation, density 0.89 g / cm ³ , melting peak temperature 162 ° C.) was used. For the innermost layer, a cyclic olefin polymer "ZEONEX (registered trademark)" (manufactured by Nippon Zeon Corporation, density 1.02 g / cm ³ , glass transition temperature 136 ° C.) was used.

For the intermediate layer, pellets in which three components consisting of LLDPE, polypropylene (PP) and an elastomer (compatibility agent) were dry-blended at a predetermined ratio were used.
As the LLDPE, a vapor phase metallocene polyethylene "Harmorex (registered trademark)" (manufactured by Japan Polyethylene Corporation, density 0.908 g / cm ³ , melting peak temperature 120 ° C.) was used.
As PP, metallocene polypropylene "Wintech (registered trademark)" (manufactured by Japan Polypropylene Corporation, density 0.90 g / cm ³ , melting peak temperature 125 ° C.) was used.
As the elastomer, the thermoplastic elastomer shown in Table 1 below was used.

As the four types of SEBS (styrene-ethylene-butylene-styrene block copolymer), "Tough Tech (registered trademark)" (manufactured by Asahi Kasei Co., Ltd., styrene content 12 to 43% by weight) was used.
As SEPS (styrene-ethylene-propylene-styrene block copolymer), "Septon (registered trademark)" (manufactured by Kuraray Co., Ltd., styrene content: 18% by weight) was used.
SEBC (styrene-ethylene-butylene-olefin crystal block copolymer), HSBR (hydrogenated styrene-butadiene rubber), and CEBC (olefin crystal-ethylene-butylene-olefin crystal block copolymer) are "Dynaron (registered)". Trademark) ”(manufactured by JSR Co., Ltd.) was used.

(Example of the first experiment)
Using the above method for producing a laminate, a laminate having an intermediate layer having the composition shown in Table 2 was produced. Using the film-formed laminate, the innermost layers were overlapped with each other, and the outer circumference of the laminate was heat-sealed except for the filling port to prepare an infusion bag-shaped pouch container having an outer dimension of 172 mm × 115 mm. After trimming so that the outer peripheral seal width was 5 mm and filling the inside of the pouch with 105 mL of water, the filling port was heat-sealed to seal the pouch.

The high-pressure sterilization treatment of the pouch after sealing was carried out by a high-pressure steam sterilizer at 121 ° C. for 20 minutes. After the high-pressure sterilization treatment, the temperature of the pouch was quickly lowered with cooling water, and then the heat seal strength and the interlayer adhesion strength of the pouch were measured.

The heat seal strength was measured by the following procedure. First, a test piece having a width of 15.0 mm and a developed length of 100 mm or more is collected from the heat-sealed portion of the pouch in a direction perpendicular to the heat-sealed portion, and the sheet portions on both sides of the heat-sealed portion are 180 ° with the heat-sealed portion of the test piece at the center. The seats on both sides were attached to the grips of the tensile tester with a grip interval of 50 mm. Next, the tensile load was measured at a constant tensile speed of 300 mm / min until the heat-sealed portion broke, and the maximum load (N / 15 mm) until the heat-sealed portion broke was defined as the heat-sealing strength.
Regarding the evaluation of heat seal strength, considering JIS Z0238 (test method for heat seal flexible packaging bags and semi-rigid containers), 23N / 15mm in "When strong heat seal strength is required for retort sterilization bags, etc." The above was evaluated as "good", and less than that was evaluated as "bad".

The interlayer adhesion strength was measured by the following procedure. First, the heat-sealed sheet portion of the pouch was cut into a 15 mm width × 150 mm length, and a part of the layers was separated from one end of the sheet using ethyl acetate. It was developed until the length of the layers separated was 20 mm or more, and both ends of the layers separated were attached to the grips of the tensile tester. Next, a tensile load was applied at a tensile speed of 5 mm / min, the length of 30 mm was delaminated, and the average load (N / 15 mm) was defined as the interlayer adhesion strength.
Regarding the evaluation of the interlayer adhesive strength, 10 N / 15 mm or more was evaluated as "good" and less than 10 N / 15 mm was evaluated as "bad" with reference to the results of the packaged products.

When measuring the interlayer adhesion strength of the pouch, the separated peeled surface was observed. Table 3 shows the results of the heat seal strength, interlayer adhesion strength, and peeling surface of the pouch.

Compared with the case where the intermediate layer is composed of either PP or LLDPE alone or two components (Nos. 1-1 to 1-6) without adding the styrene-based elastomer, the case where the styrene-based elastomer is added (No. 1-). In 7 to 1-12), the values of heat seal strength and interlayer adhesion strength before and after sterilization tended to increase significantly. In addition, the degree of decrease in strength after sterilization as compared with that before sterilization was smaller when the styrene-based elastomer was added than when the styrene-based elastomer was not added, and the performance as a container could be improved.

When PP occupies most of the composition of the intermediate layer, the peeled surface tends to be the “intermediate layer / innermost layer”. The heat seal strength reached a good level exceeding the standard value when the intermediate layer contained LLDPE in a proportion of 40% by mass or more (Nos. 1-9 to 1-12).
On the other hand, when LLDPE occupies most of the composition of the intermediate layer, the peeled surface tends to be a “surface layer / intermediate layer”. When the intermediate layer was composed of two components, LLDPE and SEBS (No. 1-12), the interlayer adhesion strength after the sterilization treatment was less than 10 N / 15 mm.

From the viewpoint of suppressing delamination even if the interlayer adhesion strength gradually decreases during long-term storage as a soft bag formulation and maintaining the commercial value of the formulation including its appearance, the interlayer adhesion strength after sterilization is high. High is preferable. Therefore, the preferable ratio of LLDPE constituting the intermediate layer to (PP + SEBS) is 40:60 to 95: 5, more preferably 40:60 to 80:20. When the styrene-based elastomer was added in Table 3, when the ratio of LLDPE to PP was 40:50 to 60:30, it became "non-peelable", showing extremely excellent performance.

(Example of the second experiment)
In order to verify the case where the addition amount of the elastomer in the intermediate layer was changed from 10% by weight, a laminate having an intermediate layer having the composition shown in Table 4 was produced. Other procedures (preparation of pouch, sterilization, measurement of heat seal strength and interlayer adhesion strength) were the same as in the first experimental example.

Table 5 shows the results of the heat seal strength, interlayer adhesion strength, and peeling surface of the pouch in the second experimental example.

When the amount of the elastomer added in the intermediate layer was 5% by weight (Nos. 2-1 to 2-6), the values of the heat seal strength and the interlayer adhesion strength tended to increase as a whole. Considering the case where 10% by weight of the elastomer is added to the intermediate layer in the first experimental example (Nos. 1-7 to 1-14), when the amount of LLDPE added to the intermediate layer is too small, the heat after sterilization It is considered that the values of the seal strength and the interlayer adhesion strength do not increase so much. On the other hand, when the amount of PP added to the intermediate layer is too small, the heat seal strength is maintained at a sufficient level even after sterilization, but the interlayer adhesion strength is significantly reduced. For this reason, it is desirable that the intermediate layer contains three components, LLDPE, PP, and an elastomer, in an appropriate ratio.

(Example of the third experiment)
In order to verify the case where the type of elastomer or the styrene content in the intermediate layer was changed, a laminate having an intermediate layer having the composition shown in Table 6 was produced. Other procedures (preparation of pouch, sterilization, measurement of heat seal strength and interlayer adhesion strength) were the same as in the first experimental example. In Tables 6 and 7, numbers 1-9 and 1-3 according to the first experimental example are also shown for comparison.

Table 7 shows the results of the heat seal strength, interlayer adhesion strength, and peeling surface of the pouch in the third experimental example.

The elastomer whose interlayer adhesive strength could be improved to the extent that it could not be peeled off even after sterilization was SEBS (Nos. 1-9 and 3-1) having a styrene content of 18% by weight or less. When SEBS having a styrene content of 30% by weight or more is added to the intermediate layer as an elastomer (Nos. 3-2 and 3-3), the heat seal strength after sterilization becomes 23 N / 15 mm or more according to the above JIS standard, It was lower than the numbers 1-9 and 3-1.
Even when a styrene-based elastomer other than SEBS was used (Nos. 3-4 to 3-6), a certain performance improving effect was observed. However, when CEBC was used as the elastomer containing no styrene block (No. 3-7), the result was not significantly different from the case where the elastomer was not added to the intermediate layer (No. 1-3).
From this, it was suggested that it is necessary to add a styrene-based elastomer to the intermediate layer in order to improve the heat seal strength and the interlayer adhesion strength.

Claims (6)

A laminated body having at least three or more layers including a structure in which a cyclic olefin resin layer, an adhesive layer, and a polypropylene resin layer are laminated in this order.
A laminate characterized in that the resin component contained in the adhesive layer is substantially composed of three components of linear low-density polyethylene, a styrene-based elastomer, and a polypropylene-based resin. The laminate according to claim 1, wherein the styrene-based elastomer is at least one selected from SEBS, SEPS, SEBC, and HSBR. The laminate according to claim 1 or 2, wherein the styrene-based elastomer is SEBS. The laminate according to any one of claims 1 to 3, wherein the styrene content in the styrene-based elastomer is 10 to 50% by weight. Claims 1 to 4 are characterized in that the polypropylene-based resin contained in the adhesive layer is a propylene-based copolymer in which at least one or more of ethylene or an α-olefin having 4 to 8 carbon atoms is copolymerized. The laminate according to any one of the above items. A container formed by using the laminate according to any one of claims 1 to 5.