JP6249224B2 - Multilayer film, laminate film and packaging material using the same - Google Patents

Description

  The present invention relates to a film that can be suitably used as a packaging material for packaging foods, medicines, cosmetics, sanitary products, industrial parts, etc., and is excellent in appearance, easy tearability, heat sealability, and content Multi-layers for laminating that can suppress degradation of laminate strength due to volatilization / penetration components from contents, delamination phenomenon such as litter floating and heat seal strength, and good appearance and easy tearability when opened The present invention relates to a film and a packaging material using the film.

  In the trend toward universal design in recent years, as a consideration for the socially vulnerable (elderly, infants, people with disabilities, etc.), methods that are easy for consumers to open, such as easy-opening and easy tearing, are regarded as important. It's getting on. As a method for imparting easy tearability to a multilayer film used for various packaging materials, for example, a type that imparts easy tearability from the polyolefin side generally used as a sealant (see, for example, Patent Documents 1 and 2) )), And a type of imparting easy tearability from the stretched substrate side that changes the stretch orientation of the stretched substrate of the outermost layer and imparts straight line / easy tearability (see, for example, Patent Document 3). ).

  As described above, the sealant usually used for the inner layer is mainly composed of a polyolefin resin such as polyethylene or polypropylene from the viewpoint of sealing properties and extrusion / molding processability. However, it is known that the polyolefin-based resin has a large gas permeability such as oxygen and carbon dioxide, and also has a large penetration of low molecular weight components and volatile components and a large penetration of solvent components such as alcohol. As a result of a decrease in seal strength after time, and penetration and plasticization of the stretched base material and sealant film to the bonded portion, the laminate strength decreases, peeling (delamination) due to laminate lifting, and appearance changes occur. There was a case.

  In addition, even if the seal strength and easy tearability can be maintained at the initial stage before packaging, the sealant resin layer swells and causes a dramatic decrease in the seal strength and whitening due to the penetration of the contents due to changes over time. There is a case. In addition, the laminate strength also decreases, and when tearing is attempted at the time of opening, delamination (peeling) occurs between the stretched base material and the sealant film. The nature deteriorated and there were many phenomena that were difficult to open.

  As a delamination prevention measure, extrusion lamination that directly extrudes the molten resin onto the substrate without using a solvent-based adhesive, or epoxy resin with excellent chemical resistance as the curing agent is used as a curing agent. Proposals have been made. However, extrusion lamination is not suitable for the production of many types of small lots because it takes a considerable amount of time to replace the raw material resin and the cost of resin loss. In addition, switching to a special adhesive requires a lot of switching time and causes productivity hindrance. In particular, adhesives that use epoxy resins are concerned about the amount and amount of elution from foods, etc. There is a problem.

  On the other hand, thermoplastic polyesters are generally known to be excellent in oil resistance and transparency, and have been used in various molded products such as food packaging. In recent years, in particular, polylactic acid-based resins that use biological resources, a type of thermoplastic polyester, have reduced the environmental impact after use, and from the perspective of resource conservation, a recycling-oriented society, and consideration for global warming. Use is widely required. However, since thermoplastic polyester is generally hard and brittle, it is easy to use from the viewpoint of tearability, but the performance balance as a film is poor, and there is a method for improving these performances in combination with polyolefin resins. Various proposals have been made (see, for example, Patent Document 4).

  In Patent Document 4, a film is formed using a resin composition obtained by mixing polyester, polyolefin, and a compatibilizing agent. However, the initial seal strength and the volatilization from the contents when a packaging bag is formed. Whether or not the seal strength is changed with time due to components, penetrating components, etc. is not taken into consideration, and whether or not it is applied to a sealant film used in combination with another base material is not described.

Japanese Patent Laid-Open No. 06-008382 JP 2001-353825 A JP 05-245990 A JP 2004-204210 A

  An object of the present invention has been made in view of the above problems, and relates to a packaging material for packaging food, medicine, cosmetics, sanitary products, industrial parts, etc., and has an appearance, easy tearability, heat seal Laminate with excellent appearance and easy tearability after storage of the contents, can suppress the delamination phenomenon caused by diffusion and penetration of volatile components from the contents into the film, and decrease in heat seal strength. It is providing the multilayer film for packaging, and the packaging material using this film.

  As a result of diligent research to solve the above-mentioned problems, the present inventors have selected a resin film to be used for a sealing layer and a layer adjacent to the multilayer film having a multilayer structure of at least three layers. By combining them, it was found that these problems can be solved, and the present invention has been completed.

  That is, the present invention provides a resin composition comprising a laminate layer (A) comprising a polyolefin resin (a) as a main component, a thermoplastic polyester resin (b1), a polyolefin resin (b2), and a compatibilizer (b3). The intermediate layer (B) mainly composed of a product and the sealing layer (C) mainly composed of a polyethylene resin (c) are laminated in the order of (A) / (B) / (C). A multilayer film characterized by the above, a laminate film obtained by laminating the film with another base film, and a packaging material comprising these films.

  The multilayer film for laminating of the present invention is excellent in performance balance such as appearance, easy tearability, high heat seal strength, laminating properties, etc., and after the contents are stored, the volatile components from the contents diffuse and penetrate into the film. -It can suppress delamination phenomenon due to swelling, decrease in heat seal strength, etc., and can maintain physical properties equivalent to those before storage in terms of appearance and easy tearability. In particular, the drop impact strength can be maintained by using a specific resin composition as the intermediate layer. In addition, by using a multilayer structure, it is possible to provide a packaging material that is curled and has excellent processing suitability and good appearance. Moreover, even if a special base material having easy tearability is not selected and used as a base material, by providing a tear starting portion such as a notch, the multi-layer film itself of the present invention can be easily teared in the vertical direction. Since it can be expressed, it has an easy-opening property that can be easily split even by a socially weak person without applying extra force. Furthermore, by using a polyethylene-based resin for the sealing layer, it is possible to ensure excellent sealing performance such as sealing performance, shrinkage of the sealing portion and crease, and easy sealing performance to general-purpose containers. Further, since the olefin resin is used for the intermediate layer, it has flexibility and toughness, has a structure that can withstand the packaging of heavy and liquid materials, and can withstand a drop impact. From these facts, the multilayer film provided by the present invention and the laminate film using the film can be suitably used as packaging materials for foods, confectionery, cosmetics, pharmaceuticals, sanitary products, industrial chemicals, miscellaneous goods and the like.

  The multilayer film of the present invention has at least three resin layers, a laminate layer (A) mainly composed of a polyolefin resin (a), a thermoplastic polyester resin (b1) and a polyolefin resin (b2). An intermediate layer (B) whose main component is a resin composition containing a solubilizer (b3), and a sealing layer (C) whose main component is a polyethylene resin (c) are (A) / (B). It is characterized by being laminated in the order of / (C).

  In the present invention, as a main component, it is essential that the specific resin or resin composition is contained in a proportion of 65% by mass or more, preferably 90% by mass with respect to the total mass of all components forming the layer. It means containing above.

  The laminate layer (A) contains a polyolefin resin (a) as a main component. As said olefin resin (a), it is excellent in the interlayer adhesiveness at the time of laminating | stacking with the intermediate | middle layer (B) mentioned later, the point which is excellent in the lamination strength at the time of laminating with another base material, and industrial availability. From this point of view, it is preferable to use a polyethylene resin or a polypropylene resin.

The polyethylene resin has a density of 0.890 to 0.970 g / cm ³ in order to maintain easy tearability, pinhole resistance, and interlayer strength between the laminate layer (A) and the intermediate layer (B). Those having a density of 0.900 to 0.965 g / cm ³ are more preferable.

  Examples of the polyethylene resin include very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), linear medium density polyethylene (LMDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), and high density. Polyethylene resin of polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) Copolymers, ethylene-based copolymers such as ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA) Copolymer; further ethylene-acrylic acid copolymer Ionomers, ethylene - mentioned ionomer methacrylic acid copolymer, and, alone, may be used by mixing two or more kinds. Among these, it is preferable to use LLDPE, LMDPE, and HDPE from the viewpoint of easy tearability and the viewpoint of pinhole resistance and rigidity as a multilayer film.

  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 and LMDPE, an ethylene monomer as a main component and a comonomer such as butene-1, hexene-1, octene-1, and 4-methylpentene are produced by a low-pressure radical polymerization method using a single site catalyst. -Copolymerized olefin. As a comonomer content rate, it is preferable that it is the range of 0.5-20 mol%, and it is more preferable that it is the range of 1-18 mol%.

  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 stability of adhesive strength between resin layers can be obtained.

Density of the polyethylene resin as mentioned above is preferably 0.890~0.970g / cm ^3, but more preferably in the range of 0.900~0.965g / 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 generally the range of 60-130 degreeC, and 70-125 degreeC is more preferable. If melting | fusing point is this range, processing stability and extrusion processability will improve. 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, 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-based resin has moderate compatibility with the resin composition described later used for the intermediate layer (B), the transparency when laminated can be maintained. Further, the interlaminar adhesive strength between the laminate layer (A) and the intermediate layer (B) can be maintained without using an adhesive resin or the like, and since it has flexibility, the pinhole resistance is also improved.

  Examples of the polypropylene resin include propylene homopolymer, propylene / α-olefin random copolymer, such as propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer. Examples include coalesced metallocene catalyst polypropylene. 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 laminate layer (A), the heat resistance of the film is improved and the softening temperature can be increased. Therefore, boiling at 100 ° C. or lower, hot filling, or 100 ° C. or higher. It can also be suitably used as a laminating film for packaging materials having excellent steam / high pressure heat sterilization characteristics such as retort sterilization.

  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.

  Furthermore, when the polypropylene resin is the main component of the laminate layer (A), the surface gloss becomes good, and by selecting the other base film to be laminated and the adhesive used at the time of lamination, the surface gloss is maintained, A transparent laminate film can also be used, and a package with excellent contents visibility can be obtained.

  The thickness of the laminate layer (A) and the thickness ratio of the total thickness are not particularly limited. The thickness is preferably 2 μm or more from the viewpoint of easy production by the coextrusion lamination method, and the thickness ratio is 5 to 75%. It is preferable that it is the range of these.

  In the multilayer film of the present invention, the intermediate layer (B) is mainly composed of a resin composition containing a thermoplastic polyester resin (b1), a polyolefin resin (b2) and a compatibilizer (b3). Other resins may be mixed as long as the effects of the present invention are not impaired. Further, the laminate layer (A) and the intermediate layer (B) may be laminated through other resin layers. At this time, as a resin that can be used for the other resin layer, it is preferable that a co-extrusion laminating method such as a polyolefin-based resin used in the laminate layer (A) can be applied.

  The thermoplastic polyester resin (b1) used in the present invention uses a divalent acid such as terephthalic acid or a derivative thereof having ester-forming ability, which is known as a general polyester, and a glycol component. Saturated polyester resins obtained by using glycols having 2 to 10 carbon atoms, other dihydric alcohols or derivatives thereof having ester forming ability can be preferably used. Among these, a polyalkylene terephthalate resin is preferable in that it has an excellent balance of processability, mechanical properties, heat resistance, and the like. Specific examples of these polyalkylene terephthalate resins include polyethylene terephthalate resin, polybutylene terephthalate resin, polyhexamethylene terephthalate resin, polycyclohexanedimethylene terephthalate resin, and the like. Furthermore, a polyalkylene terephthalate resin having crystallinity, particularly a crystalline polyethylene terephthalate resin, can be preferably used because it is particularly excellent in extrusion moldability.

  The thermoplastic polyester resin (b1) may be constituted by copolymerizing other components, if necessary, in a proportion of preferably 20% by weight or less, particularly preferably 10% by weight or less. . As the copolymer component, various acid components, alcohol components and / or phenol components, or derivatives thereof having ester forming ability can be used. Examples of the acid component include bivalent or higher aromatic carboxylic acids having 8 to 22 carbon atoms, aliphatic carboxylic acids having 4 to 12 carbon atoms, and alicyclic carboxylic acids having 8 to 15 carbon atoms, and ester forming ability. These derivatives are mentioned.

  Specifically, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, bis (p-carbophenyl) methaneanthracene dicarboxylic acid, 4-4′-diphenyldicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4 '-Dicarboxylic acid, 5-sodium sulfoisophthalic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, maleic acid, trimesic acid, trimellitic acid, pyromellitic acid, 1,3-cyclohexanedicarboxylic acid, 1,4 -Cyclohexanedicarboxylic acid and derivatives thereof having ester-forming ability. These can be used alone or in combination of two or more. Among these, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid can be preferably used because they are excellent in the physical properties, handleability, and ease of reaction of the obtained resin.

  As an alcohol component and a phenol component, it is C2-C15 bivalent or more aliphatic alcohol, C6-C20 bivalent or more alicyclic alcohol, C6-C40 bivalent or more aromatic alcohol. Or these derivatives which have phenol and ester formation ability are mentioned.

  Specifically, ethylene glycol, propanediol, butanediol, hexanediol, decanediol, neopentyl glycol, cyclohexanedimethanol, cyclohexanediol, 2,2'-bis (4-hydroxyphenyl) propane, 2,2'- Compounds such as bis (4-hydroxycyclohexyl) propane, hydroquinone, glycerin, pentaerythritol, derivatives thereof having ester forming ability, and cyclic esters such as ε-caprolactone can also be used. Among these, ethylene glycol and butanediol are preferable because they are excellent in the physical properties, handleability and ease of reaction of the obtained resin.

  Furthermore, you may comprise by partially copolymerizing a polyoxyalkylene glycol unit. Specific examples of the polyoxyalkylene glycol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and random or block copolymers thereof, alkylene glycols of bisphenol compounds (polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and these Or a modified polyoxyalkylene glycol such as an adduct, and the like can be used alone or in combination of two or more.

  The method for producing the thermoplastic polyester resin (b1) can be obtained by various polymerization methods such as melt polycondensation, solid phase polycondensation, solution polymerization and the like. In order to improve the color of the resin during polymerization, phosphoric acid, phosphorous acid, hypophosphorous acid, monomethyl phosphate, dimethyl phosphate, trimethyl phosphate, methyl diethyl phosphate, triethyl phosphate, triisopropyl phosphate, One or two or more compounds such as tributyl phosphate and triphenyl phosphate may be added.

  The thermoplastic polyester resin (b1) used in the present invention has a weight average molecular weight in the range of 1000 to 500,000 and a melting point of 110 to 200 ° C. From the viewpoint that can be produced.

  Moreover, when using polylactic acid as a thermoplastic polyester resin (b1), it is preferable from a viewpoint which can provide the biodegradability as a film. The polylactic acid is a polymer mainly composed of L-lactic acid, D-lactic acid or DL lactic acid units, or a mixture of these polymers, and can be copolymerized with an optical isomer of lactic acid. Polylactic acid may contain other hydroxycarboxylic acid as a copolymerization component, and may contain a small amount of a chain extender residue.

  Monomers such as copolymerization components copolymerized with polylactic acid include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3, 3-dimethylbutyric acid, 2- Examples thereof include bifunctional aliphatic groups such as hydroxy-3-methylbutyric acid, 2-methyllactic acid, and 2-hydroxycaproic acid, and lactones such as hydroxycarboxylic acid, caprolactone, butyrolactone, and valerolactone.

  As the polymerization method, various techniques such as condensation polymerization and ring-opening polymerization can be employed. In the condensation polymerization, L-lactic acid, D-lactic acid, DL lactic acid or the like is directly subjected to dehydration condensation polymerization to obtain polylactic acid having an arbitrary composition. In the ring-opening polymerization, a polylactic acid polymer can be obtained by selecting and using a lactide, which is a cyclic dimer of lactic acid, if necessary, with a polymerization regulator, a catalyst, or the like.

  The weight average molecular weight (Mw) of the polylactic acid used in the present invention is preferably in the range of 60,000 to 700,000, more preferably 80,000 to 400,000, and particularly preferably 100,000 to 300,000. If the weight average molecular weight (Mw) of the polylactic acid-based polymer is 60,000 or more, a practical level of mechanical properties and heat resistance can be expressed, and if the weight average molecular weight is 700,000 or less, the molding processability is inferior. There are few things.

  Examples of commercially available polylactic acid include “Lacia” manufactured by Mitsui Chemicals, “Nature Works” manufactured by Nature Works, and the like, and these may be used as they are.

  As the polyolefin resin (b2) used in the intermediate layer (B), the same polyolefin resin (a) that can be used in the laminate layer (A) can be used. At this time, the polyolefin resin (a) used for the laminate layer (A) and the polyolefin resin (b2) used for the intermediate layer (B) may be the same or different. It is preferable to use a combination of the same series of resin species such as resins or polypropylene resins, since the interlayer adhesion between the laminate layer (A) and the intermediate layer (B) becomes better.

  Examples of the compatibilizer (b3) used in the present invention include a copolymer, a block polymer, a graft polymer and the like in which different polymers are bonded.

  For example, the copolymer includes an ethylene-α-olefin copolymer, an ethylene-α-olefin-nonconjugated polyene copolymer, an ethylene- (meth) acrylic acid alkyl ester copolymer, an ethylene-vinyl acetate copolymer, and Examples thereof include a graft polymer having a main structure and a branch component from the main structure, and a copolymer composed of at least one kind or a combination of two or more kinds thereof can be used.

  Specific examples of the ethylene-α-olefin copolymer include an ethylene-propylene copolymer, an ethylene-butene copolymer, an ethylene-hexene copolymer, an ethylene-octene copolymer, and the like. Examples of the olefin-nonconjugated polyene copolymer include an ethylene-propylene-ethylidene norbornene copolymer, an ethylene-propylene-discropentadiene copolymer, and the like. Examples of the ethylene- (meth) acrylic acid alkyl ester copolymer include an ethylene-acrylic acid copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-butyl acrylate copolymer, an ethylene-isobutyl acrylate copolymer, Ethylene-acrylic acid 2-ethylhexyl copolymer, ethylene-methacrylic acid methyl copolymer, ethylene-alkyl methacrylic acid alkyl copolymer, ethylene-methacrylic acid n-butyl copolymer, ethylene-isobutyl methacrylic acid copolymer Examples thereof include a polymer and an ethylene-methacrylic acid 2-ethylhexyl copolymer.

  Examples of commercially available ethylene- (meth) acrylic acid alkyl ester copolymers include “NUC polymer” manufactured by Nihon Unicar Co., Ltd., as an ethylene-acrylic acid copolymer. Examples of the ethylene-methacrylic methyl copolymer include "Elvalloy" manufactured by Mitsui DuPont Polychemical Co., Ltd., and examples of the ethylene-methyl methacrylic acid copolymer include "Aclift" manufactured by Sumitomo Chemical Co., Ltd. and "Nucleel manufactured by Mitsui DuPont Polychemical Co., Ltd." Or the like. These can be used as they are, or modified to a graft copolymer may be used.

  Examples of the vinyl monomer that forms the branch segment when the graft copolymer is used include, for example, an alkyl acrylate ester having an alkyl chain length of 1 to 20 carbon atoms, a vinyl monomer having an acid group, and a hydroxyl group. And vinyl monomers having a group, vinyl monomers having an epoxy group, and styrene monomers.

  As the compatibilizing agent (b3) used in the present invention, a mixture of at least one elastomer or a mixture of two or more elastomers selected from polystyrene elastomers, polyester elastomers, acrylic elastomers, polyolefin elastomers and polyamide elastomers. You can also select and use.

  Examples of polyester elastomers include high melting point and high crystallinity aromatic polyester as a hard segment, and a block copolymer of amorphous polyester or amorphous polyether as a soft segment. "Primalloy A1800" series manufactured by the company can be mentioned.

  As the styrene-based elastomer, a resin comprising a styrene component and an elastomer component and containing a styrene component at a ratio of 10 to 50% by mass can be used. Elastomer components include conjugated diene hydrocarbons such as butadiene, isoprene, and 1,3-pentadiene. Examples include styrene / butadiene copolymer (SBS) elastomers, styrene / isoprene copolymer (SIS) elastomers, and the like. Can be mentioned. Examples of commercially available products include the “Hypler” series manufactured by Kuraray.

  Further, as the styrene elastomer, SBS or a resin hydrogenated to SIS (SEBS, SEPS) can be used, and as a commercial product, for example, “Tuftec” series manufactured by Asahi Kasei Corporation can be mentioned.

  As the styrene-based elastomer, a modified styrene-based elastomer containing a large amount of an elastomer component can be used, and a modified product of SEBS or SEPS is more preferably used. Specific examples include maleic anhydride-modified SEBS, maleic anhydride-modified SEPS, epoxy-modified SEBS, and epoxy-modified SEPS.

  In the present invention, the intermediate layer (B) is mainly composed of a resin composition containing a thermoplastic polyester resin (b1), a polyolefin resin (b2), and a compatibilizer (b3). The thermoplastic polyester resin (b1) is 10 to 30 parts by mass, the polyolefin resin (b2) is 60 to 88 parts by mass, and the compatibilizer (b3) is 2 to 10 parts by mass (provided that the thermoplastic polyester resin (b1) and It is preferable to use a composition formed by blending the polyolefin resin (b2) and the compatibilizer (b3) in the range of 100 parts by mass. Using a resin composition with such a mixing ratio suppresses diffusion / penetration / swelling of the content components into the film, makes it less prone to delamination, and makes it difficult to cause deterioration of the seal strength over time. Is also good.

  The thickness ratio of the central layer (B) to the total thickness of the multilayer film is preferably 20 to 80%, particularly preferably 30 to 70%.

  The sealing layer (C) in the multilayer film of the present invention is mainly composed of the polyethylene resin (c), and any of the polyethylene resins described in the laminate layer (A) can be used. . By using the polyethylene resin (c) for the seal layer (C), the seal strength and the drop impact strength are improved.

  The thickness ratio of the sealing layer (C) to the total thickness of the multilayer film is preferably 5 to 30%, and particularly preferably 10 to 25%. When the thickness ratio is within this range, the interlayer adhesive strength between the intermediate layer (B) and the seal layer (C) is good, and it is easy to make the seal strength within an appropriate range. In addition, by using a relatively thin seal layer (C), diffusion, penetration, and swelling are suitably suppressed while using an olefin-based resin, which is generally considered to easily penetrate and adsorb contents, as the seal layer. It is also possible to do.

  In order to increase the seal strength, it is effective to increase the thickness ratio of the seal layer (C). On the other hand, as the thickness ratio increases, the amount of permeation increases, so the elongation of the film increases during delamination and opening, and the easy tearability may decrease, so it may be designed according to the application and usage method. preferable. A particularly preferable thickness of the sealing layer (C) is in the range of 2 to 20 m, and more preferably in the range of 3 to 15 μm.

  The multilayer film of the present invention has a total thickness of the film in terms of ease of use (ease of laminating), drop impact resistance, and rigidity from the viewpoint of being used in combination with other base materials. Is usually in the range of 10 to 100 μm, preferably in the range of 20 to 80 μm.

  Moreover, in the laminated film formed by laminating the multilayer film of the present invention on a substrate, the ratio of the thickness of the intermediate layer (B) containing the thermoplastic polyester resin (b1) to the total thickness from the viewpoint of expressing easy tearability Is preferably 20 to 80%.

  The multilayer film of the present invention is used by being bonded to another base film, but the other base film that can be used at this time is not particularly limited. From the viewpoint of easily exhibiting the effect, it is preferable to use a plastic substrate having high rigidity and high gloss, particularly a biaxially stretched resin film. For applications that do not require transparency, an aluminum foil or an aluminum vapor deposition layer can be used alone or in combination. In this case, it is more preferable to form a laminate film obtained by laminating an aluminum foil or depositing aluminum on the laminate layer (A) of the multilayer film and then further laminating another base film.

  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.

  For each of the resin layers, an antifogging agent, an antistatic agent, a heat stabilizer, a nucleating agent, an antioxidant, a lubricant, an antiblocking agent, a release agent, an ultraviolet absorber, a coloring agent, etc. These components can be added as long as the object of the present invention is not impaired. In particular, in order to provide processing suitability during film forming and packaging suitability of a filling machine, the friction coefficient on the film surface of the layers (A) and (C) is preferably 1.5 or less, and more preferably 1.0 or less. It is preferable to add a lubricant or an antiblocking agent to the layers (A) and (C) 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 laminate layer (A), an intermediate | middle layer (B), and a sealing layer (C) is each by a separate extruder. After melting by heating and laminating (A) / (B) / (C) in a molten state by a method such as a coextrusion multi-layer die method or a feed block method, it is formed into a film by inflation, T-die chill roll method, etc. A method of laminating a base film on the laminate layer (A) after the coextrusion method is mentioned. The 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, when the thermoplastic polyester resin (b1) used in the present invention and the medium-high density polyethylene resin are used as the laminate layer (A), the difference between the melting point and Tg is large between the two. The film appearance may deteriorate or it may be difficult to form a uniform layer structure. In order to suppress such deterioration, a T-die / chill roll method that can perform melt extrusion at a relatively high temperature is preferable.

  The laminate film of the present invention is a film obtained by laminating the base film on the multilayer film obtained by the above production method. Examples of the lamination method include dry lamination, wet lamination, non-solvent lamination, and 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.

  The outermost surface of the laminate layer (A) is used in order to improve the applicability of the adhesive or pressure-sensitive adhesive as described above, or when the outermost surface is printed and then laminated with a substrate. In order to improve the adhesiveness with the adhesive, the pressure-sensitive adhesive, the printing ink, etc., it is preferable to subject the layer (A) 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 laminate film of the present invention include packaging bags, containers, container lids and the like used for foods, drugs, cosmetics, sanitary, industrial parts, sundries, magazines and the like. In particular, since the penetration of volatile components contained in the contents into the film is low, delamination can be suppressed, and the seal strength is less likely to deteriorate over time, pharmaceuticals, cosmetics, sanitary, industrial, and pharmaceutical products that contain volatile and permeable components Can be suitably used.

  In the packaging bag, the seal layer (C) of the laminate film of the present invention is overlapped with each other and heat sealed, or the seal layer (C) and the base material are overlapped and heat sealed so that the seal layer (C) is placed inside. A packaging bag formed as is preferable. For example, after cutting out the two laminated 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 end of a roll-shaped film into a cylindrical shape by an automatic packaging machine and then sealing the top and bottom.

  Furthermore, it is also possible to heat-bond a polyethylene chuck (occlusion tool) to the side sheet near the opening of the packaging bag formed with the sealing layer (C) inside. By providing a chuck (zipper) or the like, the packaging bag can be reclosed and restarted even after opening, and the contents can be stored until the contents are used up.

  It is also possible to form a lid of a packaging bag / container / container by heat-sealing with another film, sheet, or container that can be heat-sealed with the sealing layer (C).

  Since the packaging material using the laminate film of the present invention has easy tearability in the film itself, it is not necessary to provide a tear starting portion, but in order to weaken the initial tear strength and improve openability, An arbitrary tear start portion such as a V notch, an I notch, a perforation, or a micropore may be formed in the portion.

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

Example 1
As a resin for the laminate layer (A), 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 “MLDPE” . ] Was used. As the resin for the intermediate layer (B), linear low density polyethylene [density: 0.920 g / cm ³ , melting point 85 ° C., MFR: 5 g / 10 min (190 ° C., 21.18 N); That's it. ] 82 parts by mass and polylactic acid resin [Density: 1.26 g / cm ³ , Melting point: 158 ° C., MFR: 5 g / 10 min (190 ° C., 21.18 N)]; hereinafter referred to as “PLA”. ] 15 parts by mass and compatibilizer [Kuraray Co., Ltd. "Septon", hereinafter referred to as "Compatibilizer (1)". The resin composition with 3 parts by mass was used. Furthermore, LLDPE was used as the resin for the seal layer (C). These resins or resin compositions are respectively supplied to an extruder for laminate layer (A) (caliber 50 mm), an extruder for intermediate layer (B) (caliber 50 mm), and an extruder for seal layer (C) (caliber 40 mm). And melted at 200 to 230 ° C., and the melted resin or resin composition is respectively fed to a T-die / chill roll co-extrusion multilayer film production apparatus (feed block and T-die temperature: 250 ° C.) having a feed block. Co-extrusion extrusion, and the film has a three-layer structure (A) / (B) / (C), and the thickness of each layer is 6 μm / 18 μm / 6 μm (total 30 μm) After obtaining (1), the surface of the laminate layer (A) was subjected to corona treatment. The surface tension by the wetting reagent was 40 dyne / cm. A transparent biaxially stretched polyester (thickness: 12 μm) (barrier locks 1011HG, on which aluminum oxide is vapor-deposited after applying urethane adhesive (“Dick Dry LX510” manufactured by DIC) to 3 g / m ² on the treated surface side. Toray film processing) was dry laminated to obtain a laminated film (1).

Example 2
As a resin for the laminate layer (A), 85 parts by mass of MLDPE 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, “HDPE” That's it. A resin composition with 15 parts by mass was used. As resin for the intermediate layer (B), 41 parts by mass of LLDPE, 41 parts by mass of MLDPE, 15 parts by mass of PLA, a compatibilizer, “Modic” manufactured by Mitsubishi Chemical Corporation (hereinafter referred to as “Compatibilizer (2)”), 3 parts by mass. A resin mixture of 3 parts by mass of the compatibilizer (1) was used, and LLDPE was used as the resin for the sealing layer (C). A coextruded multilayer film (2) was prepared in the same manner as in Example 1 so that the thickness was (A) / (B) / (C) = 11 μm / 10 μm / 9 μm (total 30 μm), and layer (A) The surface was subjected to corona treatment, and the surface tension by the wetting reagent was 40 dyne / cm, and the 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
In Example 1, the blending ratio of the resin composition used for the intermediate layer (B) is 55 parts by mass of LLDPE, 40 parts by mass of PLA, and 8 parts by mass of the compatibilizer (1), and the thickness of each layer of the film is (A) / A coextruded multilayer film (3) was produced in the same manner as in Example 1 except that (B) / (C) = 7 μm / 15 μm / 8 μm (total 30 μm), and a corona was formed on the surface of the layer (A). Treated. 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
As the resin for the laminate layer (A), a resin composition of 50 parts by mass of MLDPE and 50 parts by mass of LLDPE was used. As the intermediate layer (B) resin, a resin composition of 87 parts by mass of MLDPE, 10 parts by mass of PLA, and 3 parts by mass of the compatibilizer (1) was used. LLDPE was used as the resin for the seal layer (C). Coextruded multilayer film as in Example 1 so that the thickness of each layer of the film is (A) / (B) / (C) = 6 μm / 18 μm / 6 μm (total 30 μm) as in Example 1. (4) was prepared, and the surface of the 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 a resin for the laminate layer (A), 20 parts by mass of MLDPE and a propylene-α-olefin random copolymer polymerized using a metallocene catalyst [density: 0.900 g / cm ³ , melting point 135 ° C., MFR: 4 g / 10 Minutes (230 ° C., 21.18 N); hereinafter referred to as “MRCP”. ) 80 parts by weight were used. As the intermediate layer (B) resin, a resin composition of 82 parts by mass of LLDPE, 15 parts by mass of PLA, and 3 parts by mass of the compatibilizer (1) was used. LLDPE was used as the resin for the seal layer (C). Coextruded multilayer film in the same manner as in Example 1 so that the thickness of each layer of the film is (A) / (B) / (C) = 9 μm / 18 μm / 3 μm (total 30 μm) as in Example 1. (5) was prepared, and the surface of the 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
MLDPE was used as the resin for the laminate layer (A). As the resin for the intermediate layer (B), a resin composition of 41 parts by mass of LLDPE, 41 parts by mass of MLDPE, 15 parts by mass of PLA, and 3 parts by mass of the compatibilizer (1) was used. Further, a resin composition of 80 parts by mass of LLDPE and 20 parts by mass of MRCP was used as the resin for the sealing layer (C). As in Example 1, the thickness of each layer of the film was (A) / (B) / (C) = 7.5 μm / 40 μm / 2.5 μm (total 50 μm). A coextruded multilayer film (6) was produced, and the surface of the 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).

Example 7
As the resin for the intermediate layer (B), 82 parts by mass of LLDPE and a polyester resin (density: 1.34 g / cm ³ , melting point 198 ° C., melt viscosity 3800 dPa · s (250 ° C.); hereinafter referred to as “PET”. A resin composition of 15 parts by mass and 3 parts by mass of the compatibilizer (1) was used. Further, as the resin for the laminate layer (A) and the seal layer (C), the same resin as in Example 1 is used, and the thickness of each layer of the film is (A) / (B) / ( C) A coextruded multilayer film (7) was produced in the same manner as in Example 1 so that 6 μm / 18 μm / 6 μm (total 30 μm), and the surface of the 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 (7).

Comparative Example 1
Ultra-low density polyethylene (density: 0.880 g / cm ³ , melting point 85 ° C., MFR: 5 g / 10 min (190 ° C., 21.18 N); hereinafter referred to as “VLLDPE”. The film was prepared so that the film thickness was 30 μm, and one surface 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
MLDPE was used as the resin for the laminate layer (A). As the resin for the intermediate layer (B), a resin mixture of 41 parts by mass of LLDPE, 41 parts by mass of MLDPE, 15 parts by mass of PLA, and 3 parts by mass of the compatibilizer (1) was used. Homopropylene polymerized using a Ziegler-Natta catalyst as the sealing layer (C) resin [Density: 0.900 g / cm ³ , Melting point 140 ° C., MFR: 4 g / 10 min (230 ° C., 21.18 N); It is called “PP”. ) Was used. Coextruded multilayer film as in Example 1 so that the thickness of each layer of the film is (A) / (B) / (C) = 6 μm / 18 μm / 6 μm (total 30 μm) as in Example 1. Was prepared, and the surface of the 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
LLDPE was used as the resin for the laminate layer (A). As the resin for the intermediate layer (B), a resin mixture of 30 parts by mass of MLDPE, 25 parts by mass of HDPE, and 45 parts by mass of PLA was used. LLDPE was used as the resin for the seal layer (C). Coextruded multilayer film in the same manner as in Example 1 so that the thickness of each layer of the film is (A) / (B) / (C) = 12 μm / 15 μm / 3 μm (total 30 μm) as in Example 1. Was prepared, and the surface of the 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 laminate film was cut into test pieces each having a size of 63 mm × 76 mm in accordance with JIS K7128, and 8 sheets were stacked using an Elmendorf tear tester (manufactured by Tester Sangyo Co., Ltd.). The tear strength was measured on the occasion. From the obtained tear strength, hand tearability was evaluated according to the following criteria.
○: Tear strength is less than 110.
X: Tear strength is 110 or more.

Content Evaluation Test Using each laminate film, a three-sided seal pouch having a length of 50 mm and a width of 80 mm was prepared, and the mass was measured. 5 ml of cleansing oil (content evaluation test 1) and isopropyl alcohol (content evaluation test 2) were added, and the opening was sealed by heat sealing. The following evaluation was performed after leaving to stand at 40 degreeC constant temperature conditions for 4 weeks in an airtight container.

Straight line cut property during tearing When the laminate film used in the above content evaluation test was stored and then torn in the MD (film flow) direction, resistance during cutting and straight line cut property were evaluated.
○: When cut, it can be opened smoothly without resistance. Almost straight cut.
Δ: When cut, there is some resistance, but it can be opened smoothly. Almost straight cut.
X: When cut, there is considerable resistance, but it cannot be opened smoothly. There is no straight cut.

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

Appearance at tear When the laminate film used in the content evaluation test was stored and then torn in the MD (film flow) direction, changes in the appearance due to floating or delamination of the laminate in the adhesive portion were observed.
○: No change in appearance ×: When tearing, delamination is observed between the base material and the sealant. Appearance changes such as lamination float before tearing.

Seal Strength Test Each laminate film was measured for mass after making a three-sided seal pouch with a length of 100 mm × width of 100 mm. 5 ml of cleansing oil (content evaluation test 1) and isopropyl alcohol (content evaluation test 2) were added, and the opening was sealed by heat sealing. After being left in a sealed container at a constant temperature of 40 ° C. for 4 weeks, the seal strength was measured to determine the strength reduction rate.
○: Less than 5% ×: 5% or more

Falling bag test Each multilayer film was cut out in 15 cm × 25 cm square, 500 ml of distilled water was sealed, and stored at 3 ° C. for 24 hours. The water-filled bag was dropped 10 times from the height of 1.5 m onto the iron plate.
○: No broken bag, no water leak ×: No broken bag, no water leak

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

Claims (13)

A laminate layer (A) containing a polyolefin resin (a) as a main component, a resin composition containing a thermoplastic polyester resin (b1), a polyolefin resin (b2) and a compatibilizer (b3) as a main component. A multilayer film comprising an intermediate layer (B) and a sealing layer (C) mainly composed of a polyethylene resin (c), which are laminated in the order of (A) / (B) / (C). . The multilayer film according to claim 1, wherein the thermoplastic polyester resin (b1) is polylactic acid. In the resin composition which is the main component of the intermediate layer (B), the thermoplastic polyester resin (b1) is 10 to 30 parts by mass, the polyolefin resin (b2) is 60 to 88 parts by mass, and the compatibilizer (b3) is The composition is used in a range of 2 to 10 parts by mass (however, the total of the thermoplastic polyester resin (b1), the polyolefin resin (b2) and the compatibilizer (b3) is 100 parts by mass). The multilayer film as described. The multilayer film according to any one of claims 1 to 3, wherein the polyolefin resin (b2) used for the intermediate layer (B) is a polyethylene resin. The total thickness of the laminate layer (A), the intermediate layer (B), and the seal layer (C) is 10 to 100 μm, and the thickness ratio of the intermediate layer (B) is 20 to 80%. ) Is in the range of 5 to 30%. 5. The multilayer film according to claim 1. The multilayer film according to claim 1, which is laminated by a coextrusion lamination method. A laminate film obtained by laminating another substrate film on the laminate layer (A) of the multilayer film according to any one of claims 1 to 6. The aluminum film is laminated on the laminate layer (A) of the multilayer film according to any one of claims 1 to 6 or aluminum vapor deposition is performed, and then another base film is further laminated. Laminate film. The laminate film according to claim 7 or 8, wherein the other base film is a biaxially stretched polyethylene terephthalate film. A packaging material comprising the laminate film according to any one of claims 7 to 9. The packaging material according to claim 10, wherein the bag is made with the seal layer (C) on the inside. The packaging material according to claim 10, wherein the bag is a re-sealable bag, the bag is made with the seal layer (C) on the inside, and a chuck is mounted on the seal surface side. The packaging material according to any one of claims 10 to 12, which is for foods, pharmaceuticals or daily necessities containing an oil component.