JP2013075438A - Coextruded multilayer film, laminate film, and packaging material using them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coextruded multilayer film which does not require a great deal of time in packaging, enables contents to be visually checked from outside in packaging, transportation and storage and has balanced piercing strength, low temperature impact and tear resistance at the same time to a packaging material filled with foods, general goods or the like, a laminate film using the same, and a packaging material made of the same.SOLUTION: The coextruded multilayer film laminated with a resin layer (A) having a polyolefin resin (a) as a main component, a resin layer (B) having thermoplastic polyurethane (b) as a main component and a resin layer (C) having a polyolefin resin (c) as a main component in the order of (A)/(B)/(C), and further the coextruded multilayer film laminated with a resin layer (D) having acid modified polyolefin (d) as a main component between layers of the resin layer (A) and the resin layer (B) and/or between layers of the resin layer (B) and the resin layer (C) are used.

Description

  The present invention relates to a multilayer film excellent in all of piercing strength, tear resistance and low temperature impact resistance, which can be suitably used for packaging an article having a protruding portion.

  Conventionally, when an article having a protruding portion such as bone-in meat, fish, frozen food or the like is packaged, the protruding portion often breaks through the package during packaging, transportation, and display after packaging. In order to prevent this, a device has been devised such as protecting and projecting the protruding portion with a cloth or a thick film or sheet as a protective member, or using a thick packaging film of 80 μm or more. For this reason, when packaging articles with protruding parts, transparency is poor due to the use of thick packaging materials and protective members, and it is difficult to visually check the contents from the outside, and packaging is troublesome. It is hanging. In addition, after use, a large amount of garbage is discharged due to excessive packaging.

  As a method for solving such a problem, a multilayer film obtained by laminating polyethylene produced by a metallocene catalyst and a polyamide resin has been proposed as having excellent puncture strength (for example, Patent Documents). 1). However, when the packaged articles collide with each other during low-temperature transportation or the like, the puncture strength with impact is insufficient, and further improvement is necessary.

JP 2001-219510 A

  The problem to be solved by the present invention is that packaging materials for filling foods and miscellaneous goods are not time-consuming at the time of packaging, and it is possible to visually check the contents from outside during packaging, transportation and storage. Another object of the present invention is to provide a coextruded multilayer film having a good balance of piercing strength, low temperature impact resistance, and tear resistance, a laminate film using the same, and a packaging material comprising these.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a multilayer film having a resin layer mainly composed of thermoplastic polyurethane as an inner layer. The invention has been completed.

  That is, the present invention mainly includes a resin layer (A) mainly composed of a polyolefin resin (a), a resin layer (B) mainly composed of a thermoplastic polyurethane (b), and a polyolefin resin (c). A co-extruded multilayer film comprising a resin layer (C) as a component laminated in the order of (A) / (B) / (C), a laminate film using the same as a sealant, and a package comprising the same The material is provided.

  The co-extruded multilayer film of the present invention has a highly versatile olefin resin layer on the film surface, and a thermoplastic polyurethane single layer film has a high friction coefficient and low rigidity. Although it is difficult to use with conventional packaging machines, it has improved piercing strength, tear resistance, and low temperature resistance while maintaining the same ease of use as conventional olefin-based packaging materials. Yes, it can be applied to frozen foods and heavy goods packaging, which was difficult with conventional products. In addition, since the thermoplastic polyurethane monolayer film is easy to block, it is necessary to use a separator on one side or both sides of the film, and the separator is discharged as waste at the time of use. do not need. Olefin-based films alone need to be thickened to increase piercing strength, but by using thermoplastic polyurethane as an intermediate layer, the total thickness can be reduced and discarded packaging. Because it can reduce the amount of material, it is an environmentally friendly film.

Hereinafter, the present invention will be described in detail.
The coextruded multilayer film of the present invention comprises a resin layer (A) mainly composed of a polyolefin resin (a), a resin layer (B) mainly composed of a thermoplastic polyurethane (b), and a polyolefin resin (c ) As a main component and (A) / (B) / (C) are laminated in this order. In the present application, “main component” means that the mass ratio of the specific resin to the total mass of each layer is 80 mass% or more, preferably 90 mass% or more.

  The resin layer (A) of the coextruded multilayer film of the present invention contains a polyolefin resin (a) as its main component. Examples of the polyolefin resin (a) include homopolymers or copolymers of α-olefins having 2 to 6 carbon atoms. The copolymerization type may be a block copolymer or a random copolymer.

  As the polyolefin-based resin (a), a resin layer (B) described later, or a resin layer (D) mainly composed of an acid-modified polyolefin (d) that is used together as necessary, can be easily coextruded, When this is used as a sealant film, the polyethylene resin (a-1) or the polypropylene resin (a-2) is used alone or from the point that it can be easily laminated to other substrates by a simple technique such as extrusion lamination. It is preferable to use a mixture.

  Examples of the polyethylene resin (a-1) include very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE). Polyethylene resin, ethylene-vinyl acetate copolymer (EVA), and the like. These may be used alone or in admixture of two or more. Among these, the coextrusion processability is good, and when the obtained multilayer film is used as a sealant, LDPE and LLDPE are preferable from the viewpoint of causing shrinkage of the film during lamination and improving packaging suitability.

  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 0.5-20 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 blocking resistance is obtained.

The density of the polyethylene resin (a-1) is preferably 0.88 to 0.94 g / cm ³ . If the density is within this range, it has moderate rigidity, excellent mechanical strength such as heat seal strength and 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 70-120 degreeC is more preferable. When the melting point is within this range, the coextrusion processability is improved. Moreover, it is preferable that MFR (190 degreeC, 21.18N) of the said polyethylene-type resin (a-1) is 2-20 g / 10min, and 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.

  Examples of the polypropylene resin (a-2) include propylene homopolymer, propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, and ethylene-propylene block copolymer. Examples include coalesced and metallocene catalyst-based polypropylene. These may be used alone or in combination of two or more. When the obtained coextruded multilayer film is rolled up and stored for a long time, it is preferable to use a crystalline propylene-based resin from the viewpoint of preventing blocking. In addition, in this application, crystallinity means having a peak of 0.5 J / g or more in the range of 95-250 degreeC in DSC (differential scanning calorimetry). When these polypropylene resins are used as the resin layer (A), the heat resistance of the film is improved, and the rigidity as a multilayer film is also improved. Therefore, it is suitable for use alone or as a packaging material for heavy objects. Can be used.

The polypropylene resin (a-2) has a melt flow rate (hereinafter referred to as “230 ° C. MFR”; a value measured at 230 ° C. and 21.18 N in accordance with JIS K7210: 1999). It is preferable that the melting point is 120 to 165 ° C. at 5 to 30.0 g / 10 minutes, more preferably, the MFR at 230 ° C. is 2.0 to 15.0 g / 10 minutes and the melting point is 125 to 162 ° C. belongs to. If the MFR and the melting point are in this range, the film shrinkage is small even in the case of heat forming such as in the secondary forming, so that the appearance can be maintained and the warp of the medium itself is not generated, and the coextrusion multilayer The film-forming property when it is used as a film is also improved. It is preferable that density is 0.890~0.910g / cm ^3, more preferably 0.895~0.905g / cm ^3.

  In particular, when a propylene-ethylene block copolymer is used, the surface is modified to a satin finish, and the generation of wrinkles when the multilayer film is wound into a roll can be suppressed. Can reduce blocking. Here, the propylene-ethylene block copolymer is a resin obtained by block polymerization of propylene and ethylene. For example, propylene obtained by polymerizing ethylene or ethylene and propylene in the presence of a propylene homopolymer. -An ethylene block copolymer etc. are mentioned.

  Further, when a mixed resin of crystalline propylene resin and ethylene / propylene rubber (hereinafter referred to as “EPR”) is used, the surface can be easily modified into a satin finish. As the crystalline propylene-based resin used at this time, a highly versatile propylene homopolymer is preferable. On the other hand, as the EPR used at this time, those having a weight average molecular weight in the range of 400,000 to 1,000,000 are preferable in that irregularities are formed on the film surface and the surface can be modified into a satin finish, A range is more preferable. In addition, the EPR content in the mixed resin is preferably in the range of 5 to 35% by mass in that the film surface can be uniformly modified into a satin finish. The MFR (230 ° C.) of the mixed resin of the crystalline propylene polymer and EPR is preferably in the range of 0.5 to 15 g / 10 minutes from the viewpoint of easy extrusion. In addition, the weight average molecular weight of the EPR was obtained by calculating a component extracted from the mixed resin by a cross fractionation method at 40 ° C. using orthodichlorobenzene as a solvent by GPC (gel permeation chromatography). It is. The content of EPR in the mixed resin is obtained from the amount of EPR extracted by cross-fractionation at 40 ° C. using orthodichlorobenzene as a solvent.

  The method for producing the mixed resin of the crystalline propylene-based resin and EPR is not particularly limited. As a specific example, for example, a propylene homopolymer and ethylene / propylene rubber are separately mixed using a Ziegler type catalyst. After producing by a combination method, a slurry polymerization method, a gas phase polymerization method, etc., a propylene homopolymer is produced in the first stage by a method of mixing both with a mixer or a two-stage polymerization method, and then the second stage. And a method of generating EPR in the presence of this polymer.

  The Ziegler-type catalyst is a so-called Ziegler-Natta catalyst, and is obtained by supporting a transition metal compound such as a titanium-containing compound or a transition metal compound on a support such as a magnesium compound. The combination with the promoter of an organometallic compound is mentioned.

  The resin layer (C) of the coextruded multilayer film of the present invention corresponds to the opposite surface of the resin layer (A). Similar to the resin layer (A), the resin layer (C) has a polyolefin resin (c) as its main component.

  As the polyolefin resin (c), like the resin layer (A), the polyethylene resin (c-1) or the polypropylene resin (c-2) is preferably used alone or in combination, and more preferably. The resin type is the same as that of the resin layer (A).

  In the coextruded multilayer film of the present invention, the resin layer (A) and the resin layer (C) are those using different resins or resin mixtures, even if they are the same resins or resin mixtures. May be. Each resin layer (A), (C) may be a single layer or may be a laminate of two or more layers.

  For example, when the co-extruded multilayer film of the present invention is used alone, and is made into a packaging material by making a box or bag, a melting point between the resins used in the resin layer (A) and the resin layer (C) It is preferable to provide a difference. That is, in order to heat-seal the resin layer (C) on the inside and using the heat seal bar from the resin layer (A) side, the resin ( The melting point of the composition is preferably higher than the melting point of the resin (composition) used for the resin layer (C), particularly preferably 10 ° C. or higher.

  In addition, when the coextruded multilayer film of the present invention is used as a sealant and laminated to another base film, a melting point between the resin (composition) used in the resin layer (A) and the resin layer (C) It is not necessary to provide a difference.

  Furthermore, when it is desired to impart easy opening when used as a packaging material, the resin layer (C) to be inside is made of 1-butene and propylene as described in JP-A-2006-213065. A heat seal layer comprising a 1-butene copolymer as an essential component and a copolymer having propylene and ethylene as essential components can also be used.

  The resin layer (B) of the coextruded multilayer film of the present invention is mainly composed of thermoplastic polyurethane (b).

  The thermoplastic polyurethane (b) is usually obtained by urethane reaction of a polyol component and a polyisocyanate component. Among urethane raw materials, polyester polyol (condensed polyester polyol, lactone polyester polyol, polycarbonate) Polyol), polyether polyol, and the like.

  Among these, the condensed polyester polyols include dicarboxylic acids such as adipic acid, succinic acid, azelaic acid, pimelic acid, sebacic acid and phthalic acid, or lower alkyl esters thereof, ethylene glycol, 1,4-butanediol, 1,6. An aliphatic diol having no side chain such as hexanediol and 1,10-decamethylene glycol, 1,2-propylene glycol, 1,3-butanediol, 2,5-dimethyl-2,5-hexanediol, Examples include those obtained by reacting an aliphatic diol having a side chain such as 2,2-diethyl-1,3-propanediol and neopentyl glycol.

  Lactone polyester polyols include lactone compounds such as β-propiolactone, pivalolactone, δ-valerolactone, ε-caprolactone, methyl-ε-caprolactone, dimethyl-ε-caprolactone, trimethyl-ε-caprolactone, What reacted with hydroxy compounds, such as a polyol, is mentioned.

  As the polycarbonate polyol, those obtained by a transesterification reaction from a hydroxy compound such as a short-chain polyol and diallyl carbonate, dialkyl carbonate or ethylene carbonate are used. For example, poly-1,6-hexamethylene carbonate, poly-2,2'-bis (4-hydroxyhexyl) propane carbonate and the like are industrially produced and easily available. As another method for obtaining the polycarbonate polyol, a so-called phosgene method (or a solvent method) can be used.

  Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxypropylene glycol, and glycerin-based polyalkylene ether glycol. In addition to the above, various polyurethane polyols can also be used.

  Among the urethane raw materials, polyisocyanates include, for example, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, cyclohexylmethane diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate, isopropylidenebis. (4-cyclohexyl isocyanate), aliphatic or cycloaliphatic diisocyanates such as methylcyclohexane diisocyanate, isophorone diisocyanate, 2,4- or 2,6-tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, 3-methyldiphenylmethane -4,4'-diisocyanate, m- or p-phenylene diisocyanate, chlorophenylene-2,4-diisocyanate Over DOO, naphthalene-1,5-diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, etc. adducts of polyhydric alcohols and polyisocyanates.

  In the urethanization reaction, chain extenders such as polyhydric alcohols and polyhydric amines can also be used. Specific product names of thermoplastic polyurethane (b) include “Pandex” (manufactured by DIC Bayer Co., Ltd.), “Curamylon” (manufactured by Kuraray Co., Ltd.), “Milactolan” (manufactured by Nippon Milactolan Co., Ltd.) It is done.

  The resin layer (B) in the coextruded multilayer film of the present invention is mainly composed of the thermoplastic polyurethane (b) as described above, but other thermoplastic resins are used in combination as long as the effects of the present invention are not impaired. You may do it. As the resin that can be used at this time, any resin that can be coextruded with the resin layer (A) and the resin layer (C) and is compatible with the thermoplastic polyurethane (b) may be used. Examples thereof include polyolefin resins such as polyethylene resins and polypropylene resins, and polyamide resins.

  In the co-extruded multilayer film of the present invention, the interlayer adhesion strength between the resin layer (A) and the resin layer (B), or the resin layer (B) and the resin layer (C) is not so strong. After laminating with another base material as a sealant film, for example, when the resin layer (C) is used as a heat seal layer, easy opening due to delamination between the resin layer (B) and the resin layer (C) is expressed. Is also possible.

  When it is desired to increase the adhesion strength between resin layers without the need for delamination as described above, an adhesive resin layer (D) mainly composed of acid-modified polyolefin (d) is provided between the respective layers. Also good.

  Examples of the acid-modified polyolefin (d) include one or more kinds of alkenes having 2 to 6 carbon atoms such as ethylene, propylene, isobutylene, 2-butene, 1-butene, 1-pentene, 1-hexene and the like. The resin has a structure derived from a mixture and a structure derived from a (meth) acrylic acid ester. Among these, as alkene, C2-C4 alkene, such as ethylene, propylene, isobutylene, 1-butene, is more preferable, ethylene and propylene are still more preferable, and ethylene is the most preferable. (Meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate , Decyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, and the like. From the viewpoint of easy availability and adhesiveness, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and hexyl acrylate are more preferable, and methyl acrylate and ethyl acrylate are more preferable. The (meth) acrylic acid ester component may be copolymerized with the olefin component, and the form thereof is not limited. Examples of the copolymerization state include random copolymerization, block copolymerization, and graft copolymerization. (Graft modification) and the like. (In addition, "(meth) acrylic acid ~" means "acrylic acid ~ or methacrylic acid ~".) Specifically, as an ethylene- (meth) acrylic acid ester copolymer, for example, Elvalloy ( Product name: Mitsui-DuPont Polychemical Co., Ltd.), Aklift (trade name: Sumitomo Chemical Co., Ltd.), etc. These may be used alone or in combination of two or more.

  The acid-modified polyolefin (d) may be acid-modified with an unsaturated carboxylic acid component. Examples of unsaturated carboxylic acid components include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid, and the like, as well as unsaturated dicarboxylic acid half esters and half amides. It is done. Of these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferable, acrylic acid and maleic anhydride are particularly preferable, and maleic anhydride is most preferable. The unsaturated carboxylic acid component may be copolymerized with the olefin component, and the form thereof is not limited. Examples of the copolymerization state include random copolymerization, block copolymerization, and graft copolymerization (grafting). Modification). Specifically, examples of the ethylene-acrylic acid copolymer include Nucrel (trade name: Mitsui / DuPont Polychemical Co., Ltd.). Examples of the ethylene- (meth) acrylic acid ester-maleic anhydride copolymer include bondine (trade name: manufactured by Tokyo Materials Co., Ltd.). These may be used alone or in combination of two or more.

  As the acid modification rate of the acid-modified polyolefin (d), it is preferable to use 3 to 40% from the viewpoint of excellent balance between adhesion and suppression of appearance defects such as film wrinkles, and 7 to 35%. It is more preferable that it is 10 to 30%.

  In addition to the acid-modified polyolefin (d), the resin layer (D) in the present invention may further contain other resins. In particular, it is preferable to use a polyolefin-based resin in combination because it is compatible with the acid-modified polyolefin (d) and can be easily co-extruded with the resin layer (A) and the resin layer (C).

  As the polyolefin resin, any of those exemplified for the polyolefin resin (a) used for the resin layer (A) can be suitably used. At this time, the polyolefin resin used in the resin layer (A) and the resin layer (C) and the polyolefin resin used in the resin layer (D) may be the same or different. In addition, the polyolefin resin used in combination in the resin layer (D) may be a single resin or a mixture of plural kinds.

  Moreover, in order to raise the interlayer adhesive strength with the resin layer (A) and the resin layer (C), a tackifier, a reaction catalyst, etc. may be added to the resin layer (D). Examples thereof include resins having an adhesive property at room temperature, including natural resins and synthetic resins. Examples thereof include rosin resins such as natural resin rosin, polymerized rosin, hydrogenated rosin, glycerin telluridine, and pentaerythritol; terpenes, aromatic terpenes, Terpene resins such as terpene phenol and hydrogenated terpene; aliphatic petroleum resin, aromatic petroleum resin, hydrogen alicyclic petroleum resin; polybutadiene liquid at room temperature, polyisoprene liquid at room temperature, polyisobutylene liquid at room temperature Etc.

  For each of the layers (A), (B), and (C), an antifogging agent, an antistatic agent, a thermal stabilizer, a nucleating agent, an antioxidant, a lubricant, an antiblocking agent, and a mold release are provided as necessary. Components such as an 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 surface friction coefficient is preferably 1.5 or less, more preferably 1.0 or less in order to impart processing suitability when forming a film or packaging suitability when used as a packaging material. It is preferable to appropriately add a lubricant, an antiblocking agent or an antistatic agent to the corresponding resin layer (A).

  The coextruded multilayer film of the present invention preferably has a total film thickness of 15 to 150 μm, particularly preferably 30 to 60 μm from the viewpoint of easy handling. If the thickness of all the films is in this range, the film can be easily formed, and the handleability is good. The thickness of the resin layer (B) is preferably 5 μm or more from the viewpoint of puncture strength and low-temperature impact property, particularly preferably in the range of 5 to 25 μm. A range of 5 to 70% is preferable.

  The method for producing the coextruded multilayer film of the present invention is not particularly limited as long as it is a coextrusion lamination method. For example, a resin or a resin mixture used for each resin layer is melted using a plurality of extruders. In addition, a method of laminating in a molten state by a co-extrusion method such as a multi-manifold die method or a feed block method, and then processing into a film using a method such as inflation or a T-die chill roll method. In the case of the T-die / chill roll method, the melt-laminated film may be nipped and cooled between a rubber touch roll, a steel belt or the like and the chill roll.

  Furthermore, the coextruded multilayer film of the present invention may be stretched in at least one axial direction. As the stretching method, various methods such as longitudinal or lateral uniaxial stretching, sequential biaxial stretching, simultaneous biaxial stretching, or tubular method biaxial stretching can be employed. Further, the stretching process may be inline or offline. The stretching method for uniaxial stretching may be a proximity roll stretching method or a rolling method. The stretching ratio of uniaxial stretching is preferably 1.1 to 80 times, more preferably 3 to 30 times in the longitudinal or transverse direction. On the other hand, the stretch ratio of biaxial stretching is preferably 1.2 to 70 times in terms of area ratio, more preferably 4 to 6 times in length, 5 to 9 times in width, and 20 to 54 times in area ratio.

  In addition, when the coextruded multilayer film of the present invention is subjected to printing or the like, or is used as a laminate film described later, the resin layer (A) or the resin layer (A) or It is preferable to perform a surface treatment on the resin layer (C). 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.

  By laminating the coextruded multilayer film of the present invention on another substrate film, a laminate film having excellent piercing strength and low temperature impact strength can be obtained.

  As a manufacturing method of the said laminate film, the method of laminating | stacking a base material through adhesive resin or an adhesive agent on the resin layer (A) of the coextruded multilayer film of this invention is mentioned. Examples of the adhesion method when laminating the substrate 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.

  The base film used for the laminate film is not particularly limited as long as it does not impair the puncture strength, low temperature impact strength and packaging suitability. For example, biaxially stretched polyester (PET), biaxially stretched polypropylene (OPP) ), Coextrusion biaxially oriented polypropylene with ethylene vinyl alcohol copolymer (EVOH) as the central layer, biaxially oriented biaxially oriented polypropylene coated with biaxially oriented ethylene vinyl alcohol copolymer (EVOH) and polyvinylidene chloride (PVDC) Examples include polypropylene, biaxially stretched nylon, and aluminum foil.

  The coextruded multilayer film of the present invention can be suitably used as various packaging materials after it is used alone or as a laminate film as described above. Examples of the packaging material include packaging bags, containers, container lids and the like used for foods, medicines, industrial parts, miscellaneous goods, magazines and the like. Especially suitable for use in medicines, industrial parts, foods and confectionery stored at room temperature, refrigerated and frozen, etc., and those with protrusions on the contents, which are filled, packed and sealed at high speed. Can do.

  The packaging material includes the resin layer (C) of the coextruded multilayer film of the present invention as a heat seal layer, the resin layers (C) are stacked on each other, heat sealed, or the resin layer (C) and the resin layer (A) or It is preferably a packaging bag formed with the resin layer (C) on the inside by overlapping and heat-sealing the base film. For example, the co-extruded multilayer film or two laminated films are cut into a desired size of a packaging bag, overlapped with each other, and heat-sealed on three sides to form a bag, and then from one side not heat-sealed. It can be used as a packaging bag by filling the contents, heat sealing and sealing. Furthermore, it is also possible to form a packaging bag by sealing the upper and lower sides after sealing the end of a roll-shaped film into a cylindrical shape by an automatic packaging machine.

  It is also possible to form a lid of a packaging bag / container / container by heat-sealing with another film, sheet, or container heat-sealable with the resin layer (C). In that case, as another film to be used, a film or sheet using a thermoplastic resin such as a polyethylene resin, a polypropylene resin, or a polyester resin can be used.

  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 layers (A) and (C), linear low density polyethylene [density 0.90 g / cm ³ , MFR (190 ° C.): 6.0 g / 10 min. LDPPE; an adipate-based polyurethane resin (specific gravity 1.20, Shore hardness A 92; hereinafter TPU) as the thermoplastic polyurethane (b), and acid-modified polyolefin resin as the resin used in the resin layer (D) (Adler SE800 manufactured by Mitsui Chemicals, Inc .; hereinafter Ad), an extruder for resin layer (A) (diameter 30 mm), an extruder for resin layer (B) (diameter 40 mm), an extruder for resin layer (C) (30 mm) and resin layer (D) extruders (30 mm) are respectively supplied with resin, and from a T die at an extrusion temperature of 230 ° C. by a coextrusion method (A) / (D) / (B) / (D) Extruded so that the ratio of the thickness of each layer of / (C) is 25/10/30/10/25% (total thickness 80 μm), cooled with a 30 ° C. water-cooled metal cooling roll, Aged 24 hours in aging room It was to obtain a coextruded multilayer film of the present invention.

Example 2
In Example 1, a coextruded multilayer film was obtained in the same manner as in Example 1 except that the total thickness of the obtained film was 50 μm.

Example 3
In Example 1, a coextruded multilayer film was obtained in the same manner as in Example 1 except that the total thickness of the obtained film was 30 μm.

Example 4
In Example 2, the ratio of the thickness of each layer of (A) / (D) / (B) / (D) / (C) was 30/10/20/10/30% (total thickness 50 μm). A coextruded multilayer film was obtained in the same manner as in Example 2 except that this was achieved.

Example 5
In Example 4, a coextruded multilayer film was obtained in the same manner as in Example 4 except that the total thickness of the obtained film was 30 μm.

Example 6
As a resin used for the resin layers (A) and (C), a propylene-ethylene random copolymer [density 0.90 g / cm ³ , MFR (230 ° C.): 7.5 g / 10 min. A coextruded multilayer film was obtained in the same manner as in Example 1 except that COPP was used.

Example 7
In Example 6, a coextruded multilayer film was obtained in the same manner as in Example 6 except that the total thickness of the obtained film was 50 μm.

Example 8
In Example 6, a coextruded multilayer film was obtained in the same manner as in Example 6 except that the total thickness of the obtained film was 30 μm.

Example 9
In Example 7, the resin layer (D) was not provided, and the ratio of the thickness of each layer (A) / (B) / (C) was 30/40/30 of the whole. In the same manner as in Example 7, a coextruded multilayer film was obtained.

Example 10
In Example 9, a coextruded multilayer film was obtained in the same manner as in Example 9 except that the total thickness of the obtained film was 30 μm.

Example 11
A biaxially stretched nylon film having a film thickness of 16 μm was laminated on the film obtained in Example 2 using a urethane adhesive to obtain a laminate film.

Comparative Example 1
A single layer film (total thickness 80 μm) made of LLDPE was used.

Comparative Example 2
A single layer film (total thickness 50 μm) made of LLDPE was used.

Comparative Example 3
A single layer film (total thickness 30 μm) made of LLDPE was used.

Comparative Example 4
A single layer film (total thickness 80 μm) made of COPP was used.

Comparative Example 5
A single layer film (total thickness 50 μm) made of COPP was used.

Comparative Example 6
A single layer film (total thickness 30 μm) made of COPP was used.

Comparative Example 7
Using nylon 6 (melting point 220 ° C., relative viscosity 3.37) and LLDPE, the thickness of each layer from the T die to the former / the latter is 20/80% (total thickness) from the T die at an extrusion temperature of 270 ° C. by co-extrusion method. 80 μm), cooled with a 30 ° C. water-cooled metal cooling roll, and aged in a aging room at 35 ° C. for 24 hours to obtain a bilayer film of Comparative Example 7.

Comparative Example 8
In Comparative Example 7, a single layer film was obtained in the same manner as in Comparative Example 7, except that the total thickness of the obtained film was 50 μm.

Comparative Example 9
The film used in Comparative Example 2 was laminated with a biaxially stretched nylon film having a film thickness of 16 μm using a urethane adhesive to obtain a laminate film.

Measuring method of puncture strength A semicircular needle having a diameter of 1.0 mm and a tip shape radius of 0.5 mm is applied to 50 ± 0.5 mm / min. The maximum load until the needle penetrated was measured.

  Tensile strength, tensile elongation, and rigidity were measured in accordance with ASTM D882.

  Impact resistance was measured according to ASTM D 3420, with a pendulum tip diameter of 1 inch and a test temperature of 0 ° C.

  The tear strength was measured according to ASTM D1424.

  The results obtained above are shown in Tables 1-3.

Claims (10)

Resin layer (A) mainly composed of polyolefin resin (a), resin layer (B) mainly composed of thermoplastic polyurethane (b), and resin layer mainly composed of polyolefin resin (c) ( And C) are laminated in the order of (A) / (B) / (C). Furthermore, an acid-modified polyolefin (d) is a main component between the resin layer (A) and the resin layer (B) and / or between the resin layer (B) and the resin layer (C). The coextruded multilayer film according to claim 1, wherein the resin layer (D) is laminated. The coextruded multilayer film according to claim 2, wherein the acid-modified polyolefin (d) is a maleic anhydride-modified polyolefin. The coextruded multilayer film according to any one of claims 1 to 3, wherein the polyolefin resin (a) is a polyethylene resin (a-1) or a polypropylene resin (a-2). The coextruded multilayer film according to any one of claims 1 to 4, wherein the polyolefin resin (c) is a polyethylene resin (c-1) or a polypropylene resin (c-2). The total thickness of the coextruded multilayer film is 15 to 150 µm, the thickness of the resin layer (B) is 5 to 70% of the total thickness, and is 5 µm or more. Coextruded multilayer film. The coextruded multilayer film according to any one of claims 1 to 6, wherein the polyolefin resin (a) and the polyolefin resin (c) are polypropylene resins and are used alone. The coextruded multilayer film according to any one of claims 1 to 7, wherein the polyolefin resin (a) is a polyethylene resin (a-1), and a base film is laminated on the resin layer (A). Laminated film characterized by being made. The packaging material according to any one of claims 1 to 8, wherein the packaging material is used for box making or bag making so that the resin layer (C) side is inside. The packaging material according to claim 9, which is for refrigerated food or frozen food.