JP6255910B2 - Multilayer film and packaging material using the same - Google Patents

Description

  The present invention relates to a packaging material for packaging foods, medicines, industrial parts, pharmaceuticals, cosmetics, sanitary goods, miscellaneous goods, magazines, etc., and more specifically, as a sealant film for laminating stretched substrates as a single unit. The present invention relates to a multilayer film that is excellent in the balance of low adsorptivity, easy-openability, heat sealability, low-temperature drop impact resistance, and suitability for packaging machinery and can be suitably used as a packaging material.

  Conventionally, a packaging material is required to have high heat seal strength and pinhole resistance from the viewpoint of protecting contents. Also, from the viewpoint of automatic packaging by a packaging machine, it is preferable that the difference between the layer in contact with the seal bar as a heat source and the melting point of the inner sealing layer sealed by thermal fusion is larger. Stretched base film such as biaxially stretched polypropylene (OPP), biaxially stretched polyester (OPET), biaxially stretched polyamide (OPA), etc., and excellent sealing properties because it is easy to set in a packaging machine. A laminate film in which stretched polyethylene (PE), unstretched polypropylene (CPP) film or the like is bonded with an adhesive has been often used.

  However, due to environmental considerations in recent years, the reduction and reduction of packaging materials, and the resulting cost reduction, are issues to be solved by packaging material manufacturers, and interest from end users is also increasing. That is, as long as the required performance can be cleared, there is a demand for a packaging form and design that can be used without a laminate, that is, by itself. Furthermore, if the film can be used as a single unit or as a sealant film for laminating, there is no need to change the materials associated with changing the packaging form, and it is effective in reducing waste that is wasted by the change. It can be demonstrated.

  On the other hand, with the trend toward universal design in recent years, easy opening and tearing are being emphasized in order to consider socially vulnerable people (old people, infants, people with disabilities, etc.). However, when trying to improve easy-openability and easy tearability, there is a problem that heat seal strength, drop impact property, etc., which are the original functions of the packaging material, are lowered.

  In order to solve the above problems, the first layer formed from a cyclic olefin resin composition mainly composed of a cyclic olefin resin and an olefin (co) polymer or a composition containing the first layer is formed. Further, a polyolefin-based multilayer laminate in which at least two layers with the second layer are laminated has been proposed (for example, see Patent Document 1). However, the laminate provided in Patent Document 1 has a problem in pinhole resistance against bending because it has a cyclic olefin resin having poor flexibility as a main component. In addition, the thickness of the multilayer laminate manufactured in the examples is 100 μm or more, and even if it can be torn by hand, there is no linear cut property, and it is torn in an unexpected direction. There was a problem that the contents get dirty on hands and clothes.

  Further, a packaging film has been proposed in which layers made of other thermoplastic resins are laminated on both sides of a layer made of an alicyclic structure-containing polymer (see, for example, Patent Document 2). Since this packaging film is as thin as 20 to 40 μm, the tearability is good. However, since 100% of the cyclic olefin resin is used, it has poor flexibility like the above-mentioned polyolefin multilayer laminate, There was a problem with pinhole resistance.

  As a method for solving these problems, the present inventor has already laminated a resin layer mainly composed of low-density polyethylene on both surfaces of a resin layer formed by using a combination of low-density polyethylene and a cyclic olefin resin. In addition, the present invention provides a multilayer film excellent in flexibility and having good pinhole resistance and linear cutability (see, for example, Patent Documents 3 to 5). However, when these multi-layer films are used alone, the rigidity is insufficient, or the heat seal layer and the surface layer are made of the same resin. Shrinkage may occur, and it is practically used as a laminate film. Furthermore, since this cut property has no directionality, the cut property is also exhibited in an unexpected direction. Especially, after tearing and opening the upper part of the bag sideways, the contents are continuously stored. There was a case where it was unsuitable in the usage form.

Japanese Patent Application Laid-Open No. 08-72210 JP 2000-334890 A JP 2007-055234 A Japanese Patent Laid-Open No. 2007-076300 JP 2007-245612 A

  The problem of the present invention has been made in view of the above problems, has a directional easy tearability, and is excellent in the balance of sufficient heat seal strength, low temperature drop impact property and suitability for packaging machinery, A multilayer film that can suppress adsorption and penetration of volatile components from the contents and can be used as a single unit, and when used as a sealant film for laminating, in addition to the above performance, an adhesive. It is providing the multilayer film which can also effectively suppress the transfer to the contents of a component, and the packaging material which uses this film.

  As a result of diligent research to solve the above problems, the present inventors have laminated a polyolefin resin layer having no cyclic structure, a polyethylene resin layer having a specific density range, a cyclic polyolefin resin layer, and a heat seal layer in this order. A multi-layer film having a multi-layer structure, and by controlling the thickness of each resin layer, it has a heat-seal strength that can withstand a certain amount of heavy-weight packaging, low-temperature drop impact, and a straight line in the lateral direction. Excellent tear resistance and curl resistance with cutability, and packaging machine suitability, low adsorptivity, low migration, etc. It can be used alone or as a sealant film for laminating. As a result, the present invention has been completed.

That is, the present invention is a resin layer composed mainly of polyolefin resin having no cyclic structure (a) (A), density 0.92g ^/ cm ³ ~0.965g ^/ cm 3 polyethylene resin (b) An intermediate layer (B) containing as a main component, an intermediate layer (C) containing 70% by mass or more of a cyclic polyolefin resin (c) as a resin component, and a polyolefin resin (d) having no cyclic structure as a main component The multilayer film (I) having a multilayer structure in which the sealing layer (D) is laminated in the order of (A) / (B) / (C) / (D), and the multilayer film of the resin layer (B) A multilayer film characterized by having a thickness ratio with respect to (I) of 30% or more and a thickness ratio of the sealing layer (D) with respect to the multilayer film (I) of 30% or less, and a packaging material using the film Is to provide.

  Since the multilayer film of the present invention has a high straight-cut property and easy tearing property in the lateral direction, it has an easy-opening property that can be easily torn even by a socially weak person without applying an extra force. In addition, it has a wide temperature range that can be sealed and excellent packaging machine suitability such as shrinkage of seals and resistance to wrinkles, low temperature drop impact resistance, heat seal strength that can withstand heavy weight packaging, moderate rigidity, and curl resistance It can be used as a single body or as a sealant film for laminating, and can be used for various purposes as a packaging material.

  As the polyolefin resin (a) used in the resin layer (A) of the multilayer film of the present invention and having no cyclic structure, a polypropylene resin (a1) or a polyethylene resin is used from the viewpoint of low cost and industrial availability. It is preferable to use (a2).

  Examples of the polypropylene resin (a1) include a propylene homopolymer, a propylene / α-olefin random copolymer, such as a propylene-ethylene copolymer, a propylene-butene-1 copolymer, and propylene-ethylene-butene-. 1 copolymer, metallocene catalyst type polypropylene, etc. are mentioned. These may be used alone or in combination. A propylene-α-olefin random copolymer is desirable, and a propylene / α-olefin random polymer polymerized using a metallocene catalyst is particularly preferable. When these polypropylene resins are used as the resin layer (A), the heat resistance of the film is improved. Furthermore, when used alone, this resin layer (A) becomes a surface layer, so that a glossy packaging material can be obtained.

  These polypropylene resins preferably have an MFR (230 ° C.) of 0.5 to 30.0 g / 10 min and a melting point of 110 to 165 ° C., more preferably an MFR (230 ° C.) of 2 0.0-15.0 g / 10 min, melting point is 115-162 ° C. If MFR and melting | fusing point are this range, the film-forming property of a film will improve.

  Examples of the other α-olefin include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1, and the like. And two or more of these may be copolymerized at the same time. As the copolymerization format, either random copolymerization or block copolymerization can be used.

  Among these, a copolymer with ethylene is preferable. Moreover, as content rate of the other alpha olefin in a copolymer, 2.0-23 mol% is preferable, More preferably, it is 2.5-15 mol%.

  As the polyethylene resin (a2), linear low density polyethylene (LLDPE), linear medium density polyethylene (LMDPE), linear high density polyethylene (LHDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), Polyethylene resins such as high-density polyethylene (HDPE), ethylene-butene-rubber copolymer (EBR), ethylene-propylene-rubber copolymer (EPR), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer Copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid Copolymer (EAA), Ethylene -Ethylene copolymer such as methacrylic acid copolymer (EMAA); and further, ionomer of ethylene-acrylic acid copolymer, ionomer of ethylene-methacrylic acid copolymer, etc. Can be used in combination. Among these, it is preferable to use LDPE, LMDPE, LHDPE, LLDPE, MDPE, and HDPE because of a good balance with easy tearability, heat resistance, drop impact resistance, and the like.

  The LDPE may be a branched low density polyethylene obtained by a high pressure radical polymerization method, and is preferably a branched low density polyethylene obtained by homopolymerizing ethylene by a high pressure radical polymerization method.

  As LLDPE, an ethylene monomer is the main component by a low-pressure radical polymerization method using a single site catalyst, and an α-olefin such as butene-1, hexene-1, octene-1, 4-methylpentene is used as a comonomer. Are copolymerized. As a comonomer content rate in LLDPE, it is preferable that it is the range of 0.5-10 mol%, and it is more preferable that it is the range of 1-7 mol%. In addition, when butene-1 is used as a comonomer, it is preferable because transparency, impact resistance, easy tearing, and the like are improved. At this time, the content of the butene monomer is in the range of 1 to 5 mol%. Most preferred.

  Examples of the single-site catalyst include various single-site catalysts such as metallocene catalyst systems such as combinations of metallocene compounds of Group IV or V transition metals and organoaluminum compounds and / or ionic compounds. In addition, the single-site catalyst has a uniform active site, so the molecular weight distribution of the resulting resin is sharper than a multi-site catalyst with a non-uniform active site. This is preferable because a resin having physical properties excellent in interlayer adhesion and blocking resistance can be obtained.

As the density of the polyethylene resin (a2), is preferably in the range of 0.920~0.965g / cm ^3, more preferably in particular in the range of 0.925~0.960g / cm ^3. If the density is within this range, it has appropriate rigidity, excellent mechanical strength such as pinhole resistance, and film film formability and extrusion suitability are improved. Moreover, it is preferable that melting | fusing point is the range of 100-140 degreeC, and 110-135 degreeC is more preferable. When the melting point is within this range, the processing stability and heat resistance are improved. The MFR (190 ° C., 21.18N) of the polyethylene resin (a1) is preferably 2 to 20 g / 10 minutes, and more preferably 3 to 10 g / 10 minutes. When the MFR is within this range, the extrusion moldability of the film is improved.

  If the thickness ratio of the resin layer (A) to the multilayer film (I) is too high, the easy tearability may be reduced, and the intended lateral tearability may not be exhibited. On the other hand, if this ratio is too low, the rigidity and heat resistance of the film will decrease, and when used alone, the resin will adhere to the heat seal bar of the packaging machine, reducing the suitability of the packaging machine, Sexuality may worsen. From these viewpoints, the thickness ratio of the resin layer (A) to the multilayer film (I) is preferably in the range of 10 to 40%, particularly preferably in the range of 10 to 30%.

  The polyolefin resin (a) used for the resin layer (A) is preferably composed mainly of the above-mentioned polypropylene resin (a1) and / or polyethylene resin (a2), and does not impair the effects of the present invention. Other resins that can be co-extruded within a range may be used in combination. The “main component” specifically means that 70% by mass or more of the resin components used in the resin layer (A) is the polyolefin resin (a), and 90% by mass or more. Is preferably a polyolefin-based resin (a).

The polyethylene resin (b) used in the intermediate layer (B) of the multilayer film (I) of the present invention may be a polyethylene resin having a density of 0.92 to 0.965 g / cm ³ , and is a linear low density. Polyethylene resins such as polyethylene (LLDPE), linear medium density polyethylene (LMDPE), linear high density polyethylene (LHDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), and ethylene -Butene-rubber copolymer (EBR), ethylene-propylene-rubber copolymer (EPR), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer ( EEA), ethylene-methyl acrylate (EMA) copolymer, Eth Ethylene copolymers such as len-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA); Examples thereof include an ionomer of an ethylene-acrylic acid copolymer, an ionomer of an ethylene-methacrylic acid copolymer, and the like. These may be used alone or in combination of two or more. Among these, LDPE, LMDPE, LHDPE, LLDPE, MDPE, HDPE, and EBR are preferably used because they have a good balance with easy tearability, heat resistance, drop impact resistance, and the like.

As described above, the density of the polyethylene resin (b1) is 0.92 to 0.965 g / cm ³ , and more preferably 0.920 to 0.960 g / cm ³ . If the density is within this range, it has appropriate rigidity, excellent mechanical strength such as pinhole resistance, and film film formability and extrusion suitability are improved. Moreover, it is preferable that melting | fusing point is the range of 100-135 degreeC, and 110-130 degreeC is more preferable. When the melting point is within this range, the processing stability is improved. Moreover, it is preferable that it is 2-20 g / 10min, and, as for MFR (190 degreeC, 21.18N) of the said polyethylene-type resin (b), it is more preferable that it is 3-10 g / 10min. When the MFR is within this range, the extrusion moldability of the film is improved.

  Since such a polyethylene resin (b) has high rigidity and low mechanical strength, it is relatively brittle compared to other polyolefin resins and has good tearability and is laminated with a cyclic olefin resin (c) described later. Transparency can be maintained. In addition, the adhesive strength between the resin layer (A), the intermediate layer (B), and the intermediate layer (C) can be maintained without using an adhesive resin, and the pinhole resistance Will also be good. Furthermore, when improving pinhole resistance, it is preferable to use LMDPE.

  As the thickness ratio of the intermediate layer (B) containing the polyethylene resin (b) as a main component to the multilayer film (I), there are directional easy-opening properties and other performance balances, in particular, low temperature impact resistance. Therefore, it is essential to be 30% or more, and it is particularly preferably in the range of 40 to 65%.

  Examples of the cyclic polyolefin resin (c) used in the intermediate layer (C) of the multilayer film (I) of the present invention include norbornene polymers, vinyl alicyclic hydrocarbon polymers, cyclic conjugated diene polymers, and the like. It is done. Among these, norbornene-based polymers are preferable. The norbornene-based polymer includes a ring-opening polymer of a norbornene-based monomer (hereinafter referred to as “COP”), a norbornene-based copolymer obtained by copolymerizing a norbornene-based monomer and an olefin such as ethylene (hereinafter, referred to as “COP”). , “COC”). Furthermore, COP and COC hydrogenates are particularly preferred. The weight average molecular weight of the cyclic polyolefin resin (c) is preferably 5,000 to 500,000, more preferably 7,000 to 300,000.

  The norbornene polymer and the norbornene monomer used as a raw material are alicyclic monomers having a norbornene ring. Examples of such norbornene-based monomers include norbornene, tetracyclododecene, ethylidene norbornene, vinyl norbornene, ethylidetetracyclododecene, dicyclopentadiene, dimethanotetrahydrofluorene, phenyl norbornene, methoxycarbonyl norbornene, methoxy And carbonyltetracyclododecene. These norbornene monomers may be used alone or in combination of two or more.

  The norbornene-based copolymer (COC) is obtained by copolymerizing an olefin copolymerizable with the norbornene-based monomer. Examples of such olefin include ethylene, propylene, and 1-butene. Examples thereof include olefins having 2 to 20 carbon atoms; cycloolefins such as cyclobutene, cyclopentene, and cyclohexene; non-conjugated dienes such as 1,4-hexadiene. These olefins can be used alone or in combination of two or more.

  In addition, the content ratio of the norbornene monomer in the norbornene copolymer (COC) is preferably 40 to 90 mol%, more preferably 50 to 80 mol%. If the content ratio is within this range, the rigidity, tearability and processing stability of the film are improved.

  As a commercially available product that can be used as the cyclic polyolefin resin (c), examples of the ring-opening polymer (COP) of the norbornene monomer include “ZEONOR” manufactured by Nippon Zeon Co., Ltd., and norbornene. Examples of the system copolymer (COC) include “Apel” manufactured by Mitsui Chemicals, Inc., “TOPAS” manufactured by TICONA, and the like.

  The intermediate layer (C) of the multilayer film (I) of the present invention contains 70% by mass or more of the above-mentioned cyclic polyolefin resin (c) as a resin component. When it is less than 70% by mass, the lateral tearing performance is deteriorated and the longitudinal tearing performance is also exhibited. When trying to tear laterally, tearing occurs in the longitudinal direction due to the force, and it does not become linear cut property but oblique direction. It may become. As the resin to be mixed with the cyclic polyolefin resin (c), the aforementioned polyolefin resin is preferable from the viewpoint of compatibility and versatility.

  The cyclic polyolefin resin (c) is preferably a norbornene copolymer having a glass transition point of 100 ° C. or less from the viewpoint of extrusion suitability, cost, and easy tearability.

  In addition, the thickness ratio of the intermediate layer (C) to the multilayer film (I) is preferably 30% or less from the viewpoint of cost, film formability, and curl property of the film, and is described below by a coextrusion lamination method. From the viewpoint of good film formation, it is preferably 5% or more. Even such a relatively thin intermediate layer (C) can exhibit the low adsorption property and penetration resistance of the volatile components inherent in the cyclic polyolefin resin as the performance of the multilayer film.

  The sealing layer (D) in the multilayer film (I) of the present invention is a polyolefin resin (d) having no cyclic structure, and the resin layer (A), the intermediate layer (B), the intermediate layer (C) and Although it will not specifically limit if it can be laminated | stacked, The above-mentioned polyethylene-type resin, a polypropylene resin, etc. are mentioned. When the thickness ratio of the sealing layer (D) to the multilayer film (I) exceeds 30%, the lateral tear performance tends to be lowered. On the other hand, if this ratio is too low, a phenomenon in which the seal strength is extremely reduced occurs. Therefore, as a thickness ratio, it is essential that it is 30% or less, Preferably it is the range of 10-25%.

Since the layer (D) is a sealing layer, propylene polymerized using a polyethylene resin or metallocene catalyst having a density of 0.89 to 0.93 g / cm ³ from the viewpoint of strength, hermeticity, and suitability for packaging machinery. It is preferable to use a polypropylene resin which is a -α-olefin random copolymer.

  In particular, when packaging using a packaging machine alone, a resin having a difference in melting point between the resin layer (A) corresponding to the surface layer of the multilayer film (I) and the sealing layer (D) is used. It is preferable to use it from the viewpoint that the temperature of the seal bar can be increased and the sealing strength can be improved. Specifically, the melting point of the polyolefin resin (a) used in the resin layer (A) is the sealing layer (D It is preferable to use a resin that is higher by 10 ° C. or more than the melting point of the polyolefin-based resin (d) used in (1).

  The layer structure of the multilayer film (I) of the present invention is the layer (A), (B), (C) and (D) in the order of (A) / (B) / (C) / (D). The thickness ratio of the layer (B) to the multilayer film (I) is 30% or more, and the thickness ratio of the sealing layer (D) to the multilayer film (I) is 30% or less. If the ratio of the thickness of the resin layers (B) and (D) to the total thickness of the multilayer film is within this range, transparency, directional easy tearability, low temperature drop impact, heat sealability, etc. will be well-balanced. Can do.

  Furthermore, the multilayer film (I) of the present invention preferably has a film thickness of 20 to 60 μm, more preferably 20 to 50 μm. If the thickness of the film is within this range, stable sealing strength, suitability for packaging machinery, excellent pinhole resistance, easy tearing performance, and the like can be obtained.

  For each of the resin layers (A), (B), (C) or (D), an antifogging agent, an antistatic agent, a thermal stabilizer, a nucleating agent, an antioxidant, a lubricant, Components such as an anti-blocking agent, a release agent, an ultraviolet absorber, and a colorant can be added within a range that does not impair the object of the present invention. In particular, the resin layer (A) and (D) have a friction coefficient of 1.5 or less, preferably 1.0 or less, in order to impart processing suitability during film forming and packaging suitability of the filling machine. It is preferable to add a lubricant or an antiblocking agent to the layers (A) and (D) as appropriate.

  Although it does not specifically limit as a manufacturing method of the multilayer film of this invention, For example, each resin or resin mixture used for a resin layer (A), an intermediate | middle layer (B), an intermediate | middle layer (C), and a sealing layer (D), Each is heated and melted in separate extruders and laminated in the order of (A) / (B) / (C) / (D) in a molten state by a method such as a co-extrusion multi-layer die method or a feed block method. Examples thereof include a coextrusion method in which a film is formed by a T-die / chill roll method or the like. This coextrusion method is preferable because the thickness ratio of each layer can be adjusted relatively freely, and a multilayer film excellent in hygiene and cost performance can be obtained. Furthermore, since the polyethylene resin used in the intermediate layer (B) of the present invention has a large difference in softening point (melting point) from the high-density polyethylene used in the other layers and the cyclic polyolefin resin, phase separation and gel May occur. In order to suppress the occurrence of such phase separation and gel, the T-die / chill roll method capable of performing melt extrusion at a relatively high temperature is preferable.

  Since the multilayer film (I) of the present invention is obtained as a substantially unstretched multilayer film by the above production method, secondary molding such as deep drawing by vacuum molding is also possible.

  Furthermore, in order to improve the adhesiveness with the printing ink and the laminating suitability when used as a sealant film for laminating, the resin layer (A) is preferably subjected to a surface treatment. Examples of such surface treatment include corona treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, surface oxidation treatment such as ozone / ultraviolet treatment, and surface unevenness treatment such as sandblasting. Corona treatment is preferable.

  Examples of the packaging material comprising the multilayer film of the present invention include packaging bags and packaging containers used for foods, drugs, industrial parts, miscellaneous goods, magazines and the like.

  The packaging bag is formed by using the sealing layer (D) of the multilayer film (I) of the present invention as a heat sealing layer, heat sealing by overlapping the sealing layers (D), or a resin layer (A) and a sealing layer (D). It is preferable that the packaging bag is formed by stacking and heat-sealing. For example, after cutting out the two multilayer films into the desired size of a packaging bag and overlapping them to heat-seal three sides to form a bag, the contents are filled from one side that is not heat-sealed. It can be used as a packaging bag by heat sealing. Furthermore, it is also possible to form a packaging bag by sealing the top and bottom after sealing the end of a roll film into a cylindrical shape by an automatic packaging machine.

  It is also possible to form a packaging bag / container by stacking and heat-sealing another film that can be heat-sealed with the sealing layer (D). At that time, as another film to be used, a film such as LDPE or EVA having relatively low mechanical strength can be used. In addition, a laminate film in which a film such as LDPE or EVA and a stretched film having relatively good tearability, for example, a biaxially stretched polyethylene terephthalate film (OPET), a biaxially stretched polypropylene film (OPP), or the like, is used. Can do.

  The multilayer film of the present invention can be used even if it is bonded to another substrate. Other substrates that can be used at this time are not particularly limited, but from the viewpoint of easily manifesting the effects of the present invention, a plastic substrate having high rigidity and high gloss, particularly biaxial. It is preferable to use a stretched resin film. For applications that do not require transparency, aluminum foils can be used alone or in combination.

  Examples of the stretched resin film include biaxially stretched polyester (PET), easily tearable biaxially stretched polyester (PET), biaxially stretched polypropylene (OPP), and biaxially stretched polyamide (from the viewpoint of easy tearability, etc. PA), coextrusion biaxially oriented polypropylene with ethylene vinyl alcohol copolymer (EVOH) as the central layer, biaxially oriented biaxially oriented polypropylene, biaxially oriented ethylene vinyl alcohol copolymer (EVOH), and coextrusion biaxially coated with polyvinylidene chloride (PVDC) Examples thereof include stretched polypropylene. These may be used alone or in combination.

  Examples of the lamination method in the case of laminating the substrate on the multilayer film obtained by the above production method to form a laminate film include dry lamination, wet lamination, non-solvent lamination, extrusion lamination, and the like.

  Examples of the adhesive used in the dry lamination include a polyether-polyurethane adhesive and a polyester-polyurethane adhesive. Various pressure-sensitive adhesives can be used, but a pressure-sensitive pressure-sensitive adhesive is preferably used. Examples of the pressure-sensitive adhesive include, for example, a polyisobutylene rubber, a butyl rubber, a rubber adhesive obtained by dissolving a mixture thereof in an organic solvent such as benzene, toluene, xylene, hexane, or a bisethylene acid rosin in the rubber adhesive. A blend of tackifiers such as ester, terpene / phenol copolymer, terpene / indene copolymer, or 2-ethylhexyl acrylate / n-butyl acrylate copolymer, 2-ethylhexyl acrylate / ethyl acrylate / Examples thereof include an acrylic pressure-sensitive adhesive prepared by dissolving an acrylic copolymer having a glass transition point of −20 ° C. or less such as a methyl methacrylate copolymer in an organic solvent.

  In particular, laminating adhesives are generally cured with polyol / isocyanate, and are widely used for high-functional applications such as retort applications. Conventionally, the bonding is generally a combination of an aluminum foil and a sealant film. However, with the advent of transparent vapor deposition technology, various transparent vapor deposition films that have both barrier properties and transparency have become commercially available, and in addition to the demand for improved visibility of contents, transparent vapor deposition films and sealant films Bonding is increasing.

  Therefore, it is common to add a silane coupling agent such as epoxy silane or aminosilane silane to the adhesive in order to provide adhesion between the sealant film and the deposited film.

  However, if the amount of epoxy silane is increased in order to maintain adhesion, the dissolution of epoxy silane into the food will increase. Further, when the same adhesive is used for laminating a film without vapor deposition, the silane coupling agent is eluted more than in the vapor deposition configuration, and the configuration requires the replacement of the adhesive.

  As a polyol used for the adhesive for laminating, for example, a polyol itself described later, or a polyester polyol obtained by reacting a polyol with a polycarboxylic acid described later, or ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, Ethylene oxide, propylene oxide, butylene starting from compounds having two active hydrogen atoms such as trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, etc. Examples thereof include polyethers obtained by addition polymerization of monomers such as oxide, styrene oxide, epichlorohydrin, tetrahydrofuran and cyclohexylene.

  Examples of the polyol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, and 1,6-hexane. Diol, neopentyl glycol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanediol, 1 , 4-cyclohexanedimethanol, triethylene glycol, polycaprolactone diol, dimer diol, bisphenol A, hydrogenated bisphenol A, and other glycols Polyesters obtained by ring-opening polymerization reaction of cyclic ester compounds such as propiolactone, butyrolactone, ε-caprolactone, δ-valerolactone, β-methyl-δ-valerolactone, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol , Ethylene oxide, propylene oxide, starting with compounds having two active hydrogen atoms such as trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, etc. Examples include polyethers obtained by addition polymerization of monomers such as butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, and cyclohexylene.

  Examples of the polycarboxylic acids include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid. Acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis (phenoxy) ethane-p , P'-dicarboxylic acids and anhydrides or ester-forming derivatives of these dicarboxylic acids; p-hydroxybenzoic acid, p- (2-hydroxyethoxy) benzoic acid, ester-forming derivatives of these dihydroxycarboxylic acids, dimer acids, etc. Of the polybasic acids.

  Examples of the polyisocyanate include organic compounds having at least two isocyanate groups in the molecule. Examples of the organic polyisocyanate include tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), lysine diisocyanate, trimethylhexamethylene diisocyanate, 1 , 3- (isocyanatomethyl) cyclohexane, 1,5-naphthalene diisocyanate, polyisocyanate such as triphenylmethane triisocyanate; adducts of these polyisocyanates, burettes of these polyisocyanates, or of these polyisocyanates Derivatives (modified products) of polyisocyanates such as isocyanurates are exemplified.

  Moreover, you may use what reacted the said isocyanate and the said polyol with the mixing ratio from which an isocyanate group becomes excess.

  In the adhesive, the equivalent ratio polyol / isocyanate of the hydroxyl group equivalent of the polyol and the isocyanate equivalent of the polyisocyanate is preferably 0.5 to 5.0.

  Examples of the epoxy silane include methacrylsilane-based silane coupling agents such as 3-methacryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycid Examples thereof include xylpropyltriethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane.

<Regulations in Europe>
In Switzerland, Swiss Ordinance SR817.002.21 has legalized elution regulations for inks and coating agents that do not come into contact with food, and is currently the only positive list (PL) of food non-contact materials in the world. This PL is classified according to whether the toxicity data of the substance is known or unknown, and is provided with a specific migration limit (SML).

  Epoxysilane has unknown toxicity data, and SML is considered to be less than 10 μg / kg-food. The multilayer film (I) of the present invention has been confirmed to satisfy this regulation when the epoxysilane elution amount was measured as will be described later, and can be applied as a food packaging material and a pharmaceutical packaging material. is there.

  In the packaging material using the multilayer film of the present invention, in order to weaken the initial tear strength and improve the openability, an arbitrary tear start portion such as a V notch, an I notch, a perforation, or a microporous is formed in the seal portion. It is preferable to do.

  Since the multilayer film of the present invention has a directional and easy tear property, the packaging form includes a drawstring packaging in which the upper part of the package is bound with a tape, a metal fitting, a resin closure, or the like, and the flow direction of the film. It is suitable for resealable packaging to which a wire fastener such as a chuck or a zipper having a reseal function in the vertical direction (TD) is attached.

  Next, the present invention will be described in more detail with reference to examples and comparative examples.

Example 1
As a resin for the resin layer (A), homopolypropylene [density: 0.900 g / cm ³ , melting point, 162 ° C., MFR: 7 g / 10 min (230 ° C., 21.18 N); hereinafter, “PP (1)” That's it. ) Was used. As a resin for the intermediate layer (B), linear medium density polyethylene [density: 0.930 g / cm ³ , melting point 125 ° C., MFR: 5 g / 10 min (190 ° C., 21.18 N); hereinafter referred to as “LMDPE” . ] Was used. As a resin for the intermediate layer (C), a ring-opening polymer of a norbornene-based monomer [“Appel APL8008T” manufactured by Mitsui Chemicals, MFR: 15 g / 10 min (260 ° C., 21.18 N), glass transition point: 70 ° C .; Hereinafter, it is referred to as “COC (1)”. ] Was used. As a resin for the sealing layer (D), linear low density polyethylene [density: 0.915 g / cm ³ , melting point 110 ° C., MFR: 5 g / 10 min (190 ° C., 21.18 N); hereinafter referred to as “LLDPE” . ] Was used. The resin layer (A) extruder (caliber 50 mm), intermediate layer (B) extruder (caliber 50 mm), intermediate layer (C) extruder (caliber 40 mm), seal layer (D), respectively. Supplied to an extruder (40 mm diameter) and melted at 200 to 250 ° C., and the melted resin is a T-die / chill roll co-extrusion multilayer film production apparatus having a feed block (feed block and T-die temperature: 250 ° C. ) And co-melt extrusion is performed, and the layer structure of the film is a four-layer structure of (A) / (B) / (C) / (D), and the thickness of each layer is 9 μm / 15 μm / 3 μm / After obtaining the multilayer film (1) which is 3 μm (total 30 μm), the surface of the resin layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. After applying urethane adhesive on the treated surface side to 3.5 g / m ² , biaxially stretched polyester (thickness 12 μm) (melting point 260 ° C., manufactured by Toyobo) is dry laminated, and laminate film (1) is applied. Obtained.

Example 2
As resin for the resin layer (A), 50 parts by mass of PP (1) and a propylene / α-olefin random copolymer [density: 0.900 g / cm ³ , melting point 135 ° C., MFR: 7 g / 10 min (230 ° C., 21 18N), hereinafter referred to as “PP (2)”. ) A resin mixture with 50 parts by weight was used. The resin for the intermediate layer (C) is a ring-opening polymer of 60 parts by mass of COC (1) and a norbornene monomer [[Appel APL6015T] manufactured by Mitsui Chemicals, MFR: 10 g / 10 min (260 ° C., 21.18 N ), Glass transition temperature: 145 ° C .; hereinafter referred to as “COC (2)”. A resin mixture with 40 parts by weight was used. For the intermediate layer (B) and the sealing layer (D), the thickness of each layer of the film was (A) / (B) / (C) / (D) = 3 μm / 18 μm / 3 μm / 6 μm as in Example 1. A multilayer film (2) was produced in the same manner as in Example 1 so that the total thickness was 30 μm, and the surface layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. Biaxially stretched polyester was dry laminated on the treated surface in the same manner as in Example 1 to obtain a laminate film (2).

Example 3
As resin for the resin layer (A), 80 parts by mass of PP (1), linear medium density polyethylene [density: 0.93 g / cm ³ , melting point 125 ° C., MFR: 5 g / 10 min (190 ° C., 21. 18N); hereinafter referred to as “LMDPE”. A resin mixture with 20 parts by mass was used. As the resin for the intermediate layer (B), a resin mixture of 95 parts by mass of LMDPE and 5 parts by mass of COC (1) was used. A multilayer film (3) as in Example 1 so that the thickness of each layer of the film is (A) / (B) / (C) / (D) = 7 μm / 29 μm / 4 μm / 10 μm (total 50 μm) Was prepared, and the surface of the resin layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. Biaxially stretched polyester was dry laminated on the treated surface in the same manner as in Example 1 to obtain a laminate film (3).

Example 4
PP (1) as the resin for the resin layer (A), 50 parts by mass of LMDPE as the resin for the intermediate layer (B) and high-density polyethylene [density: 0.966 g / cm ³ , melting point 128 ° C., MFR: 10 g / 10 min (190 ° C, 21.18 N); hereinafter referred to as “HDPE”. A resin mixture with 50 parts by mass was used. As the resin for the intermediate layer (C), a resin mixture of 85 parts by mass of COC (1) and 15 parts by mass of LMDPE was used. Propylene / α-olefin random copolymer polymerized using 70 parts by mass of LLDPE and a metallocene catalyst as the sealing layer (D) [density: 0.900 g / cm ³ , melting point 130 ° C., MFR: 4 g / 10 min (230 ° C, 21.18 N); hereinafter referred to as “MRCP”. ) 30 parts by weight were used. A multilayer film (4) in the same manner as in Example 1 so that the thickness of each layer of the film is (A) / (B) / (C) / (D) = 6 μm / 15 μm / 3 μm / 6 μm (total 30 μm) Was prepared, and the surface of the resin layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. Biaxially stretched polyester was dry laminated on the treated surface in the same manner as in Example 1 to obtain a laminate film (4).

Example 5
As the resin for the resin layer (A), a resin mixture of 70 parts by mass of LMDPE and 30 parts by mass of high-density polyethylene (HDPE) was used. Moreover, LMDPE was used as resin for intermediate | middle layers (B). COC (1) was used as the resin for the intermediate layer (C). As resin for the sealing layer (D), 85 parts by mass of MRCP and ethylene butene rubber [density: 0.890 g / cm ³ , melting point: 66 ° C., MFR: 3 g / 10 min (190 ° C., 21.18 N); hereinafter, “EBR " 15 parts by weight of resin mixture was used. The multilayer film (5) was prepared in the same manner as in Example 1 so that the thickness of each layer of the film was (A) / (B) / (C) / (D) = 6 μm / 16 μm / 5 μm / 3 μm (total 30 μm). Was prepared, and the surface of the resin layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. Biaxially stretched polyester was dry laminated on the treated surface in the same manner as in Example 1 to obtain a laminate film (5).

Example 6
As a resin for the resin layer (A), linear high-density polyethylene [density: 0.947 g / cm ³ , melting point 130 ° C., MFR: 6 g / 10 min (190 ° C., 21.18 N); hereinafter referred to as “LHDPE” . A resin mixture of 80 parts by mass and 20 parts by mass of high-density polyethylene (HDPE) was used. As the resin for the resin layer (B), a resin mixture of 80 parts by mass of LMDPE, 10 parts by mass of COC (1) and 10 parts by mass of HDPE was used. A multilayer film (6) as in Example 1 so that the thickness of each layer of the film is (A) / (B) / (C) / (D) = 9 μm / 15 μm / 3 μm / 5 μm (total 32 μm) Was prepared, and the surface of the resin layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. Biaxially stretched polyester was dry laminated on the treated surface in the same manner as in Example 1 to obtain a laminate film (6).

Comparative Example 1
PP (1) was used as the resin for the resin layer (A), and LMDPE was used as the resin for the intermediate layer (B). COC (1) was used as the resin for the intermediate layer (C). LLDPE was used as the resin for the seal layer (D). A multilayer film was prepared in the same manner as in Example 1 so that the thickness of each layer of the film was (A) / (B) / (C) / (D) = 20 μm / 4 μm / 3 μm / 3 μm (total 30 μm). The surface of the resin layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. Biaxially stretched polyester was dry laminated on the treated surface in the same manner as in Example 1 to obtain a laminated film.

Comparative Example 2
LMDPE was used as the resin for the resin layer (A). As the resin for the intermediate layer (B), ultra-low density polyethylene [density: 0.880 g / cm ³ , melting point 85 ° C., MFR: 5 g / 10 minutes (190 ° C., 21.18 N); hereinafter referred to as “VLLDPE”. ] Was used. As the resin for the intermediate layer (C), a resin mixture of 50 parts by mass of COC (1) and 50 parts by mass of LMDPE was used. As the resin for the sealing layer (D), very low density polyethylene (VLLDPE) was used. A multilayer film was prepared in the same manner as in Example 1 so that the thickness of each layer of the film was (A) / (B) / (C) / (D) = 6 μm / 16 μm / 6 μm / 2 μm (total 30 μm). The surface of the resin layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. Biaxially stretched polyester was dry laminated on the treated surface in the same manner as in Example 1 to obtain a laminated film.

Comparative Example 3
PP (1) was used as the resin for the resin layer (A). LMDPE was used as the resin for the intermediate layers (B) and (C). VLLDPE was used as the resin for the sealing layer (D). A multilayer film was prepared in the same manner as in Example 1 so that the thickness of each layer of the film was (A) / (B) / (C) / (D) = 10 μm / 30 μm / 3 μm / 7 μm (total 50 μm). Then, the surface of the resin layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. Biaxially stretched polyester was dry laminated on the treated surface in the same manner as in Example 1 to obtain a laminated film.

Comparative Example 4
A resin mixture of 50 parts by mass of LMDPE and 50 parts by mass of VLLDPE was used as the resin for the resin layer (A). PP (1) was used as the resin for the intermediate layer (B). COC (1) was used as the resin for the intermediate layer (C). VLLDPE was used as the resin for the sealing layer (D). A multilayer film was prepared in the same manner as in Example 1 so that the thickness of each layer of the film was (A) / (B) / (C) / (D) = 6 μm / 29 μm / 5 μm / 10 μm (total 50 μm). Then, the surface of the resin layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. Biaxially stretched polyester was dry laminated on the treated surface in the same manner as in Example 1 to obtain a laminated film.

Comparative Example 5
LMDPE was used as the resin for the resin layer (A). VLLDPE was used as the resin for the intermediate layer (B). As a resin for the intermediate layer (C), a ring-opening polymer of a norbornene monomer [“Apel APL6015T” manufactured by Mitsui Chemicals, MFR: 10 g / 10 min (260 ° C., 21.18 N), glass transition point: 145 ° C .; "COC (2)". ] Was used. PP (1) was used as the resin for the sealing layer (D). Coextruded multilayer film in the same manner as in Example 1 so that the thickness of each layer of the film was (A) / (B) / (C) / (D) = 10 μm / 5 μm / 3 μm / 12 μm (total 30 μm) Was prepared, and the surface of the resin layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. Biaxially stretched polyester was dry laminated on the treated surface in the same manner as in Example 1 to obtain a laminated film.

Comparative Example 6
PP (1) was used as the resin for the resin layer (A). LMLDPE was used as the resin for the intermediate layer (B). COC (1) was used as the resin for the intermediate layer (C). Coextruded multilayer film in the same manner as in Example 1 so that the thickness of each layer of the film was (A) / (B) / (C) / (D) = 12 μm / 3 μm / 10 μm / 5 μm (total 30 μm) Was prepared, and the surface of the resin layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dynexxxx / cm. Biaxially stretched polyester was dry laminated on the treated surface in the same manner as in Example 1 to obtain a laminated film.

Comparative Example 7
PP (1) was used as the resin for the resin layer (A). LMLDPE was used as the resin for the intermediate layer (B). As the resin for the intermediate layer (C), a resin mixture of 60 parts by mass of COC (1) and 40 parts by mass of LMDPE was used. LLDPE was used as the resin for the sealing layer (D). Coextruded multilayer film in the same manner as in Example 1 so that the thickness of each layer of the film was (A) / (B) / (C) / (D) = 7 μm / 14 μm / 2 μm / 7 μm (total 30 μm) Was prepared, and the surface of the resin layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. Biaxially stretched polyester was dry laminated on the treated surface in the same manner as in Example 1 to obtain a laminated film.

Hand-cut property test The obtained multilayer film before lamination is cut into test pieces each having a size of 63 mm × 76 mm in accordance with JIS K7128, and torn using an Elmendorf tear tester (manufactured by Tester Sangyo Co., Ltd.). Strength was measured. From the obtained tear strength, hand tearability was evaluated according to the following criteria. Furthermore, when the actual hand was torn, the condition of the cut surface was observed.
○: The tear strength is less than 410 or the cut surface is torn in a straight line.
X: The tear strength is 410 or more or the cut surface is not distorted and linearly torn.

Curl resistance The obtained multilayer film before lamination was cut out 10 cm in length and width and stored for 24 hours at 40 ° C. and 90% humidity. The film was spread on a flat surface and the height at which both end surfaces were rolled up was measured and evaluated according to the following criteria.
○: Less than 3 cm in height Δ: 3 cm or more in height ×: Both ends of the film overlap and become completely rounded

Suitability for packaging machine The obtained multilayer film before lamination was subjected to the following vertical pillow packaging with an automatic packaging machine to form a bag.
Packaging machine: Rika Kaken Co., Ltd. Unipacker NUV472

Vertical (envelope sticker) seal: speed 30 bags / min, horizontal heat seal temperature 150 ° C, air gauge pressure 4kg / cm ² , vertical heat seal temperature 130 ° C to 160 ° C while changing in 10 ° C increments (D) And the resin layer (A) were sealed while being overlapped. A flat bag measuring 200 mm long and 150 mm wide was used.
Horizontal (gap-attached) seal: speed 30 bags / min, vertical heat seal temperature 150 ° C, air gauge pressure 4kg / cm ² , while changing from horizontal heat seal temperature 120 ° C to 150 ° C in increments of 10 ° C (D) Sealed each other. A flat bag measuring 200 mm long and 150 mm wide was used.

Shrinkage / wrinkle test The film was fused to the heat-seal bar by shrinkage and heat seal bar by observing the appearance of the seal part of the flat bag with horizontal (gap-attached) seal and vertical (envelope-attached) seal. In addition, although the result of 120 degreeC is only a horizontal seal | sticker and the result of 160 degreeC is only a vertical seal | sticker, the result of 130, 140, 150 degreeC has shown the result of both.
○: No shrinkage and wrinkles in the seal part △: Some shrinkage and wrinkles in the seal part ×: There is shrinkage and wrinkles in the seal part

Horizontal seal
The film formed with a horizontal (gap-attached) seal was naturally cooled at 23 ° C., and then a test piece was cut into a strip shape having a width of 15 mm. This test piece was peeled 180 ° at a rate of 300 mm / min using a tensile tester (manufactured by A & D Co., Ltd.) in a thermostatic chamber at 23 ° C. and 50% RH, and the heat seal strength was measured. The heat sealability was evaluated according to the following criteria from the obtained heat seal strength value.
○: Heat seal strength is 300 g / 15 mm width or more.
X: Heat seal strength is less than 300 g / 15 mm width.

Low temperature drop impact test Using the above packaging machine, packaging was performed while filling 400 g of udon so as to have a size of 300 mm in length and 200 mm in width under optimum conditions, and an actual package product was prepared. The packaging udon stored at 0 ° C. overnight was dropped onto an iron plate from a height of 1.5 m, the number of times of bag breaking was counted, and a drop impact test at low temperature was performed.
○: Number of drops before breaking the bag is 10 times or more ×: Number of drops before breaking the bag is less than 10 times

Glossiness test According to the method of JIS-K7105, the surface gloss on the resin layer A side was measured with UGV-5D (Suga Test Co., Ltd.). From the obtained numerical values, the surface gloss was evaluated according to the following criteria.
○: Numerical value 110 or more ×: Numerical value less than 110

Seal strength test (after lamination)
Each laminate film was made into a three-side sealed pouch having a length of 100 mm and a width of 100 mm, and after measuring the mass, 2 g of methyl salicylate was added, and the opening was sealed by heat sealing. After leaving in a sealed container at 45 ° C. for 2 weeks, the seal strength was measured to obtain the strength reduction rate.
○: Less than 5% ×: 5% or more

Laminate strength The laminate strength before and after the laminate film used in the adsorption test was measured to determine the strength reduction rate.
○: Less than 10% ×: 10% or more

Appearance (after lamination)
Each laminate film was made into a three-side sealed pouch having a length of 100 mm and a width of 100 mm, 10 ml of 0.5% limonene solution (100% ethanol diluted) was added, and the opening was sealed by heat sealing. After standing in a sealed container at a constant temperature of 25 ° C. for 2 weeks, changes in the appearance due to floating or delamination of the laminate in the adhesive portion were observed.
○: No change in appearance ×: Appearance change such as floating float

Adsorption test After making a three-sided seal pouch with a length of 100 mm x width 100 mm for each laminate film, measuring the mass, and then adding 2 g of methyl salicylate (adsorption test 1) and chlorine dioxide [Kraepelin gel: Daiko Pharmaceutical] (adsorption test 2) The opening was sealed by heat sealing. After leaving in a sealed container for 2 weeks under a constant temperature condition at 25 ° C., the container was opened, the contents were removed, the mass of the pouch was measured, and the adsorption rate was determined from the rate of change.
○: Less than 5% ×: More than 5%

Elution test for adhesive component (epoxysilane) (conforming to EN13130)
The aluminum foil 12 μm and the multilayer film are laminated with a specific adhesive containing epoxy silane (see the following preparation example). Aging of adhesive application amount 2.2 g / m 2, 40 ° C. × 24 hours. A pouch was prepared so that the contact area with the contents was 200 cm 2 and filled with 100 ml of 95% ethanol as a food pseudo-solvent and sealed. After the prepared pouch is stored at 60 ° C. for 5 days, the ethanol content is concentrated and the silane compound is quantified by gas chromatography mass spectrometry (GC-MS).
GC-MS: GC2100A manufactured by Shimadzu Corporation
Column: Polydimethylsiloxane type ○: Epoxysilane elution amount less than 3 μg / kg-food ×: Epoxysilane elution amount 3 μg / kg-food or more

<Adhesive>
Preparation Example 1 [Main agent preparation example]
In a polyester reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, moisture separator, etc., 10.0 parts of ethylene glycol, 21.1 parts of neopentyl glycol, 10.0 of 1,6-hexanediol Part, 8.0 parts of Tsunodim 216, 21.5 parts of isophthalic acid, 21.5 parts of terephthalic acid, 23.4 parts of adipic acid and 0.006 parts of titanium catalyst, the upper temperature of the rectifying tube exceeds 100 ° C The internal temperature was kept at 240 ° C. by gradually heating so as not to occur. The reaction was further continued until the acid value became 2 mgKOH / g or less. The pressure was reduced to 10 mmHg or less and held for 1.5 hours to complete the esterification reaction, and an intermediate polyester polyol having a hydroxyl value of 28 was obtained. To 100 parts of the obtained intermediate polyester polyol, 8.9 parts of isophorone diisocyanate was added and heated to 120 ° C. to carry out a urethanization reaction until NCO% was 3.1 to obtain a polyester urethane polyisocyanate. . This was diluted with 111.9 parts of ethyl acetate and then the temperature was lowered to 40 ° C. and kept at 50 ° C. for about 1 hour to obtain a polyurethane polyester polyol resin solution U having a nonvolatile content of 60%.

Adjustment Example 2 [Additive]
Epoxysilane is 3-glycidoxypropyltrimethoxysilane (KBM-403 manufactured by Shin-Etsu Silicone), aminosilane is 3-aminopropyltrimethoxysilane (KBM-903 manufactured by Shin-Etsu Silicone), and phosphoric acid is 85 manufactured by Wako Pure Chemical Industries, Ltd. As the% phosphoric acid, styrene-maleic anhydride copolymer (SMA), a reagent of Mw 7,500 manufactured by Wako Pure Chemical Industries, Ltd. was used.

  Adhesive composition: 100 parts by weight of polyol U, 10 parts by weight of polyisocyanate I, 1 part by weight of epoxysilane, 160 parts by weight of ethyl acetate

  The results obtained above are shown in Tables 1-2.

  The multilayer film of the present invention has a directional easy cut property. It also has excellent packaging machine suitability, pinhole resistance due to bending, heat seal strength / rigidity that can withstand heavy weight packaging, and curl resistance. Therefore, the multilayer film of the present invention is suitable for a packaging material for packaging foods, medicines, industrial parts, sundries, magazines and the like.

Claims (13)

Intermediate to the resin layer composed mainly of polyolefin resin having no cyclic structure (a) the (A), density 0.92g ^/ cm ³ ~0.965g ^/ cm 3 polyethylene resin (b) as a main component Layer (B), intermediate layer (C) containing 70% by mass or more of cyclic polyolefin resin (c) as a resin component, seal layer (D) containing polyolefin resin (d) having no cyclic structure as a main component Is a multilayer film (I) having a multilayer structure in which (A) / (B) / (C) / (D) are laminated in this order, and the thickness ratio of the resin layer (B) to the multilayer film (I) Is 30% or more, the thickness ratio of the intermediate layer (C) to the multilayer film (I) is 30% or less, and the thickness ratio of the sealing layer (D) to the multilayer film (I) is 30% or less. A multilayer film characterized by The melting point of the polyolefin resin (a) used in the resin layer (A) of the multilayer film (I) is 10 ° C. or more higher than the melting point of the polyolefin resin (d) used in the seal layer (D). Multilayer film. The multilayer film according to claim 1 or 2, wherein the olefin resins (a) and (d) are a polypropylene resin and / or a polyethylene resin. The multilayer film according to any one of claims 1 to 3 , wherein the cyclic polyolefin resin (c) is a norbornene polymer. The multilayer film according to claim 4, wherein 60% by mass or more of the cyclic polyolefin resin (c) is a norbornene polymer having a glass transition point of 100 ° C. or less. The polyolefin resin (d) The multilayer film of any one of claims 1 to 5 density of the polyethylene resin in the range of ^{0.89g / cm 3 ~0.93g / cm 3} . The multilayer film according to any one of claims 1 to 6 , wherein the polyolefin-based resin (d) is a propylene-α-olefin random copolymer polymerized using a metallocene catalyst. The multilayer film according to any one of claims 1 to 7 , wherein the multilayer film (I) is laminated by a coextrusion lamination method. The multilayer film according to any one of claims 1 to 8 , wherein the total thickness of the multilayer film (I) is in the range of 20 to 60 µm. A packaging material comprising the multilayer film according to any one of claims 1 to 9 . The packaging material according to claim 10 , wherein the upper part of the packaging bag is for a drawstring packaging bag bound with a jig. The packaging material according to claim 10 , which is for a resealable packaging bag to which a wire fastener is attached. The packaging material according to any one of claims 10 to 12 , which is for food or medicine.