JPWO2018198794A1 - Sealant film and packaging material - Google Patents

Abstract

An outer layer, an intermediate layer and an inner layer are laminated films, the outer layer and the inner layer contain a polyethylene resin, the intermediate layer contains a linear low density polyethylene and a cyclic olefin resin, and in the intermediate layer The content of the cyclic olefin-based resin in the contained resin component is 20 to 40% by mass, and the standardized molecular orientation MORc value when the reference thickness measured by the microwave type molecular orientation meter is 60 μm is The sealant film characterized by being 1.025 or more can realize excellent easy tearability and straight cutability, and can suppress internal fusion and appearance unevenness of the packaging material at the time of high temperature treatment.

Description

  The present invention relates to a sealant film for use in a retort package or the like which can be sterilized or cooked by heating or pressure in a packaged state of food or the like, and a packaging material using the sealant film.

  Flexible packaging using plastic materials is used worldwide as a packaging material for food, and shows an increasing trend with the spread to emerging countries. Under these circumstances, retort foods that have been subjected to high temperature, pressure and heat sterilization (retort sterilization) are expected to have a growing demand in the future food packaging market due to their convenience. Retort foods can be distributed at room temperature, and in addition to ease of eating, they are easy to handle in distribution, and are expected to be expanded to areas where the development of the cold chain is insufficient.

  When retort food is eaten, it is generally hot-watered and warmed with boiling water in many cases, and after heating, the film is torn open from the notch provided at the upper end of the packaging bag. For this reason, the resin film used for retort packaging is required to be easily tearable. As a retort film having easy tearability, for example, a propylene-based film in which the birefringence is controlled in a specific range is disclosed using a resin in which a low crystalline ethylene-based elastomer is blended with a propylene-ethylene block copolymer (See Patent Document 1).

  In addition, as a packaging material having easy cutability, a cyclic olefin-based resin and a linear low density polyethylene resin are contained as a packaging material used for a soft bag filled with a chemical solution such as physiological saline or electrolytic solution. A packaging material is disclosed having an intermediate layer and an inner layer and an outer layer of linear low density polyethylene resin (see Patent Document 2).

JP 2011-162667 A JP, 2009-172902, A

  In the above-mentioned propylene-based film in which the birefringence is promoted, the decrease in tear strength is recognized by the improvement of the film rigidity, but the control of the directionality of the tear is not sufficient, and the straight cut property of tearing straight Improvement was required. Moreover, in heavy goods for business use, distribution in cold regions, and the like, the packaging material using an ethylene-propylene copolymer as a sealant is not sufficient in impact resistance, and there may be a case where a bag breakage accident occurs.

  Although the packaging material used for the above-mentioned soft bag has easy cutability and straight cutability, when applied to retort use, further improvement in cutability is desired.

  The problem to be solved by the present invention is to provide a sealant film and a packaging material which have suitable bag-proof resistance and which are excellent in easy tearability and straight cutability.

Furthermore, in addition to the above-mentioned subject, in the present invention, it makes it a subject to provide a sealant film which has suitable sealability.
Furthermore, in the present invention, in addition to the above-mentioned problems, it is an object of the present invention to provide a sealant film which does not cause internal fusion bonding and appearance unevenness of the packaging material during high temperature treatment.

  The present invention comprises a laminated film in which an outer layer (A), an intermediate layer (B) and an inner layer (C) are laminated, the outer layer (A) and the inner layer (C) contain a polyethylene resin, and the intermediate layer (B) And a linear low density polyethylene (b1) and a cyclic olefin resin (b2), wherein the content of the cyclic olefin resin (b2) in the resin component contained in the intermediate layer (B) is 20 The above problem is solved by a sealant film which is 40 to 40% by mass, and the standardized molecular orientation MORc value is 1.025 or more when the reference thickness measured by a microwave molecular orientation meter is 60 μm. is there.

  Further, the present invention is a method for producing a sealant film comprising a laminated film in which an outer layer (A), an intermediate layer (B) and an inner layer (C) are laminated by a coextrusion inflation method, wherein the outer layer (A) is The outer layer resin to be formed and the inner layer resin to form the inner layer (C) contain a polyethylene resin, and the intermediate layer resin to form the intermediate layer (B) is linear low density polyethylene (b1) and cyclic Content of the said cyclic olefin resin (b2) in the resin component which contains an olefin resin (b2) and is contained in resin for said intermediate | middle layers is 20-40 mass%, 1.0-2.3 The above-mentioned subject is solved by the manufacturing method of the sealant film which carries out coextrusion inflation molding with a blow ratio of 20 and a drawdown ratio of 20 to 60.

  The sealant film of the present invention has easy tearability and straight-line cutability that is more suitable for the above configuration, so that the packaging bag using the sealant film of the present invention may cause the contents to be spilled upon opening or after opening begins to occur. And scattering hardly occurs. In particular, when applied to retort packaging applications, cutting can be performed with simple and suitable straightness. In addition, it is possible to realize suitable bag-proof property, in particular, suitable bag-proof property under low temperature, and to have suitable flowability.

  Moreover, the sealant film of the present invention is easy to realize a packaging material which does not cause internal fusion and appearance unevenness at high temperature treatment such as retort sterilization treatment while realizing suitable tearability. Therefore, the sealant film of the present invention can be suitably applied to a packaging material for high temperature treatment such as a retort food packaging material which requires high temperature sterilization. Furthermore, the sealant film of the present invention is suitable for use in these packaging materials because it is easy to realize a suitable sealing property.

  The sealant film of the present invention comprises a laminated film in which an outer layer (A), an intermediate layer (B) and an inner layer (C) are sequentially laminated, and the outer layer (A) and the inner layer (C) contain a polyethylene resin. A resin component contained in the intermediate layer (B), wherein the intermediate layer (B) between the outer layer (A) and the inner layer (C) contains a linear low density polyethylene (b1) and a cyclic olefin resin (b2) It is a sealant film whose content of the said cyclic olefin resin (b2) in it is 20-40 mass%. In addition, the standardized molecular orientation MORc value is 1.025 or more when the reference thickness measured by the microwave type molecular orientation meter is 60 μm.

[Outer layer (A)]
The outer layer (A) of the sealant film of the present invention contains a polyethylene resin. As said polyethylene-based resin, such as ultra low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), linear medium density polyethylene (LMDPE), medium density polyethylene (MDPE), etc. Polyethylene resin, ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene -Ethylene-based copolymers such as ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA); and ethylene -Ionomer of acrylic acid copolymer, ethylene Ionomers of acrylic acid copolymer can be exemplified. These polyethylene resins may be used alone or in combination of two or more. Among these, ultra low density polyethylene, linear low density polyethylene, low density polyethylene, and linear medium density polyethylene can be preferably used since suitable impact resistance can be easily obtained, and linear low density polyethylene is particularly preferable. . It is also preferable to use high density polyethylene (HDPE) in combination with these medium and low density polyethylene.

  Linear low density polyethylene is mainly composed of ethylene monomer by low pressure radical polymerization method using a single site catalyst, with butene-1, hexene-1, octene-1, 4-methylpentene etc. as a comonomer. Of an α-olefin of The comonomer content in LLDPE is preferably in the range of 0.5 to 20 mol%, more preferably in the range of 1 to 18 mol%.

  As said single site catalyst, various single site catalysts, such as metallocene catalyst systems, such as combination of the metallocene compound of periodic table group IV or V transition metal and an organoaluminum compound and / or an ionic compound, are mentioned. In addition, since the single-site catalyst has a uniform active site, the molecular weight distribution of the resulting resin is sharp compared to a multi-site catalyst having a non-uniform active site, so low molecular weight components are formed when forming a film. Is preferable because a resin having physical properties excellent in stability of sealing strength and impact resistance can be obtained.

  In the outer layer (A), the polyethylene resin is preferably contained in an amount of 60% by mass or more based on the total amount of resin components forming the layer, since it is easy to obtain suitable impact resistance. It is more preferable to contain, and it is further more preferable to contain by 90 mass% or more. Above all, it is preferable to contain only a polyethylene resin as a resin component, and to make 60% by mass or more in the resin component to be linear low density polyethylene, more preferably 80% by mass or more, 90% by mass or more It is further preferred that

  In the outer layer (A), another resin of the above-mentioned polyethylene-based resin may be used in combination as long as the effects of the present invention are not impaired. Examples of other resin species that can be used in combination include polyolefin resins other than the above-mentioned polyethylene resins, and the like, and a propylene homopolymer, a propylene-ethylene copolymer, a propylene-butene-1 copolymer, a propylene-ethylene- Examples thereof include polypropylene resins such as butene-1 copolymer and metallocene catalyst based polypropylene.

  When these other resins are used, it is preferably 40% by mass or less in the resin component contained in the outer layer (A), more preferably 20% by mass or less, and 10% by mass or less Is more preferred. The lower limit is not particularly limited, but may be suitably used at a content of 1% by mass or more according to the desired characteristics.

The outer layer (A) used in the sealant film of the present invention preferably has an average density of resin components used in the layer of 0.940 g / cm ³ or more, more preferably 0.940 to 0.945 g / it is a layer of cm ^3. By setting the average density of the resin component in the above range, it is possible to preferably suppress the appearance unevenness at the time of high temperature treatment such as retort sterilization treatment. When the resin used for the said layer is resin a, resin b, resin c ..., the average density concerned uses the density of these resins in the layer d _a , d _b , d _c. the mass of the resin _{W a, W b,} upon the _W c · · _·, in _{(d a W a + d b} W b + d c W c ···) / (W a + W b + W c ···) It is the calculated density.

The density of each resin used in the outer layer (A) is not particularly limited as long as the average density of the resin component to be used is in the above range, but in the case of a polyethylene resin, it is preferably 0.880 g / cm ³ or more, It is more preferable that it is 0.920 g / cm < ³ > or more, and it is especially preferable that it is 0.940-0.950 g / cm < ³ >. Moreover, it is preferable to use 0.920 g / cm ³ or more of other resins.

  The MFR of the resin component used for the outer layer (A) is 0.1 to 20 g / 10 min (190 ° C., 21.18 N), preferably 0.3 to 10 g / 10 min (190 ° C., 21.18 N), Preferably it is 0.5-5 g / 10 minutes (190 degreeC, 21.18 N). It is preferable at the point from which favorable film formability is acquired in various multilayer film-forming methods as MFR is this range.

[Intermediate layer (B)]
The middle layer (B) of the sealant film of the present invention contains linear low density polyethylene (b1). By containing the said linear low density polyethylene, it becomes easy to suppress suitably the appearance nonuniformity at the time of the retort sterilization process at the time of high temperature processing with suitable impact resistance. The density of the linear low density polyethylene (b1) is preferably 0.937 g / cm ³ or more, more preferably 0.940 g / cm ³ or more, and still more preferably 0, because the appearance unevenness can be particularly easily suppressed. It is .940-0.945 g / cm < ³ >. Moreover, it is preferable that it is 0.940 g / cm < ³ > or more, and, as for the average density of the resin component in the layer of intermediate | middle layer (B), it is more preferable that it is a layer of 0.940-0.945 g / cm < ³ >.

  The MFR of linear low density polyethylene (b1) is 0.1 to 20 g / 10 min (190 ° C., 21.18 N), preferably 0.3 to 10 g / 10 min (190 ° C., 21.18 N), Preferably it is 0.5-5 g / 10 minutes (190 degreeC, 21.18 N). It is preferable at the point which is excellent in compatibility with cyclic olefin resin (b2) as MFR is this range, and favorable film-forming property is obtained in various multilayer film-forming methods.

  The content of the linear low density polyethylene (b1) in the intermediate layer (B) is a resin component contained in the intermediate layer (B) because it is easy to obtain suitable impact resistance and heat resistance at high temperature treatment. It is preferable that it is 60-80 mass% of, and it is more preferable that it is 65-75 mass%.

  By containing the cyclic olefin resin (b2) in the intermediate layer (B) of the sealant film of the present invention, it is possible to realize excellent easy tearability and straight-line cuttability. Examples of the cyclic olefin resin (b2) include norbornene polymers, vinyl alicyclic hydrocarbon polymers, cyclic conjugated diene polymers and the like. Among these, norbornene polymers are preferable. Also, as a norbornene-based polymer, 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 , “COC”) and the like. Also preferred are COP and COC hydrides. The weight average molecular weight of the cyclic olefin resin is preferably 5,000 to 500,000, and more preferably 7,000 to 300,000.

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

  The norbornene-based copolymer is a copolymer of the norbornene-based monomer and an olefin copolymerizable with the norbornene-based monomer, and as such an olefin, for example, the number of carbon atoms such as ethylene, propylene, 1-butene, etc. Olefins having 2 to 20; cycloolefins such as cyclobutene, cyclopentene and cyclohexene; and non-conjugated dienes such as 1,4-hexadiene.

  The content of the cyclic olefin resin (b2) contained in the intermediate layer (B) is preferably 20 to 40% by mass in the resin component contained in the intermediate layer (B), and 25 to 35% by mass It is more preferable that By making content of cyclic olefin resin (b2) into the said range, suitable easy tearability and straight cut property can be implement | achieved, without impairing impact resistance.

  The cyclic olefin resin (b2) used in the intermediate layer (B) preferably has a glass transition temperature of 140 ° C. or lower, more preferably 50 to 140 ° C., and 70 to 120 ° C. It is further preferred that By using the cyclic olefin resin (b2) having the glass transition temperature, it is easy to obtain good heat resistance and rigidity, and it is easy to improve the tear resistance against dropping or the like. Moreover, it becomes easy to obtain favorable compatibility, and it becomes easy to suppress an appearance nonuniformity. The glass transition temperature (Tg) is a value obtained by measurement by DSC.

  The MFR of the cyclic olefin resin (b2) is 0.2 to 17 g / 10 min (230 ° C., 21.18 N), preferably 3 to 15 g / 10 min (230 ° C., 21.18 N), more preferably 5 to 5 13 g / 10 min (230 ° C., 21.18 N). It is preferable at the point which is excellent in compatibility with a linear low density polyethylene (b1) as MFR is this range, and favorable film-forming property is obtained in various multilayer film-forming methods.

  As a commercial item which can be used as cyclic olefin resin used for the present invention, as a ring-opening polymer (COP) of a norbornene monomer, for example, Nippon Zeon Co., Ltd. "ZEONOR (ZEONOR)" etc. may be mentioned. Examples of the copolymer (COC) include "APEL" manufactured by Mitsui Chemicals, Inc., "TOPAS" manufactured by Polyplastics, and the like.

  As the resin component in the intermediate layer (B), it is preferable to contain only the above-mentioned linear low density polyethylene (b1) and cyclic olefin resin (b2), but within the range which does not impair the effect of the present invention You may use together other resin other than a resin component. Examples of other resin types that can be used in combination include polyethylene resins and polypropylene resins exemplified in the above outer layer (A).

  When using these other resins, it is preferable to set it as 20 mass% or less in the resin component contained in an intermediate | middle layer (B), and it is more preferable to set it as 10 mass% or less. The lower limit is not particularly limited, but may be suitably used at a content of 1% by mass or more according to the desired characteristics.

[Inner layer (C)]
The inner layer (C) in the sealant film of the present invention is a layer containing a polyethylene-based resin, preferably a layer having an average density of resin components in the layer of 0.940 g / cm ³ or more. The inner layer (C) is a layer to be a heat seal layer of the sealant film.

  The polyethylene resin used for the inner layer (C), the resin usable in combination with the polyethylene resin, etc. can be exemplified by the same ones as the outer layer (A), and preferable ones are also the same. Further, the same range as the outer layer (A) can be exemplified as a preferable range also with respect to the content of the polyethylene resin and the other resin, and the density and the average density of the resin component in the inner layer.

  In the inner layer (C), high density polyethylene (HDPE) is used in combination with medium and low density polyethylene such as ultra low density polyethylene, linear low density polyethylene, low density polyethylene, and linear medium density polyethylene Is also preferred. When using medium and low density polyethylene in combination with high density polyethylene, the content of medium and low density polyethylene in the resin component used for the inner layer (C) is 40 to 80 mass%, and the content of high density polyethylene Is preferably 20 to 60% by mass, and more preferably 45 to 75% by mass of the medium / low density polyethylene and 25 to 55% by mass of the high density polyethylene.

[Sealant film]
The sealant film of the present invention is a laminated film in which the outer layer (A), the intermediate layer (B) and the inner layer (C) are sequentially laminated. The sealant film of the present invention can realize a packaging material which does not have internal fusion and appearance unevenness at the time of high temperature treatment such as retort sterilization treatment while having suitable easy tearability and rectilinear cutability by the constitution. Moreover, since it is easy to implement | achieve favorable sealing performance and a bag-proof property, it is suitable for retort packaging material use.

  The sealant film of the present invention has a standardized molecular orientation MORc value of 1.025 or more, preferably 1.030 or more, more preferably, when the reference thickness measured by a microwave type molecular orientation meter is 60 μm. Is 1.035 or more. The upper limit value is not particularly limited, but is preferably 1.20 or less, more preferably 1.080 or less. In the present invention, by setting the MORc value of the sealant film in the above range, it is possible to realize excellent tear resistance and straight-line cutability together with suitable tear resistance.

The said MORc value is a value which shows the degree of molecular orientation, and is measured by the following measuring methods.
The sample plane (film plane) is arranged vertically in the traveling direction of the microwaves in a microwave resonant waveguide of a known microwave type molecular orientation meter. Then, in a state where the sample is continuously irradiated with microwaves whose vibration direction is biased in one direction, the sample is rotated in a plane perpendicular to the traveling direction of the microwaves by 0 to 360 °, and the microwaves transmitted through the sample The degree of molecular orientation MOR is determined by measuring the intensity.
The normalized molecular orientation MORc in the present embodiment is a MOR value when the reference thickness is tc, and can be obtained by the following equation.
MORc = (tc / t) x (MOR-1) + 1
(Tc: reference thickness to be corrected, t: sample thickness)
Here, as the MORc value is closer to 1.000, it indicates that the film is an isotropic film.
The normalized molecular orientation MORc can be measured at a resonance frequency around 4 GHz by a known molecular orientation meter, for example, a microwave type molecular orientation meter MOA-2000A or MOA-2012A manufactured by Oji Scientific Instruments.

  The thickness of the sealant film of the present invention may be suitably adjusted according to the application and the mode of use, but the total thickness is 20 from the viewpoints of heat resistance in packaging application, bag resistance during distribution, heat sealability, etc. It is preferable that it is -150 micrometers, and it is more preferable that it is 40-100 micrometers.

  As the thickness ratio of each layer, the thickness ratio of the outer layer (A) is preferably in the range of 10 to 40% of the total thickness of the sealant film, from the viewpoint of sealability, easy tearability and laminateability. More preferably, it is%. The thickness ratio of the inner layer (C) is preferably in the range of 10 to 40%, and more preferably in the range of 15 to 30%.

  The thickness ratio of the intermediate layer (B) is preferably 10 to 80%, more preferably 15 to 60%, and particularly preferably 20 to 50%. In the sealant film of the present invention, suitable cut properties can be realized even when the thickness ratio of the intermediate layer (B) is low (for example, 40% or less, more preferably 30% or less). Cuttable sealant films can be obtained at low cost.

  As a specific thickness, the thickness of the outer layer (A) is preferably 2 to 60 μm, and more preferably 3 to 45 μm. The thickness of the intermediate layer (B1) is preferably 4 to 120 μm, and more preferably 8 to 100 μm. The thickness of the inner layer (C) is preferably 2 to 60 μm, and more preferably 3 to 45 μm.

The sealant film of the present invention is a laminated film in which the outer layer (A), the intermediate layer (B) and the inner layer (C) are sequentially laminated, but a gas barrier layer can be formed between the layers without impairing the effects of the present invention. Another optional layer such as an easy adhesion layer may be provided. In the sealant film of the present invention, the average density of the resin component in all the layers is preferably 0.940 g / cm ³ or more, and more preferably 0.940 to 0.945 g / cm ^3. preferable. For this reason, when providing another layer, it is preferable that the average density of the resin component in the layer of the said other layer is also the said range.

  In each layer of the sealant film of the present invention, various additives may be blended as long as the effects of the present invention are not impaired. Examples of the additive include an antioxidant, a weathering stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a lubricant, a nucleating agent, a pigment and the like.

[Production method]
As a method for producing the sealant film of the present invention, for example, the resins (including a resin mixture containing two or more kinds of resins and additives) used for each layer of the multilayer film are heated and melted by separate extruders, After laminating in a molten state by a method such as an extrusion multi-layer die method or a feed block method, a co-extrusion method of forming a film by an inflation method may be mentioned. This co-extrusion method is preferable because the ratio of thickness of each layer can be adjusted relatively freely, and a film excellent in hygiene and cost-effectiveness can be obtained. As the inflation method, air-cooling inflation method is preferable, and upward air-cooling inflation method can be particularly preferably used. Moreover, it can be set as a multilayer film by using a plurality of extruders and a multilayer circular die. After extruding a cylindrical molten resin upward using these, the cylindrical molten resin is expanded and taken up if necessary, and after cooling and solidifying the molten resin by air cooling, it is appropriately cut and desired. A film can be obtained.

  In the present invention, since a sealant film having a specific orientation can be easily obtained, the blow ratio during the coextrusion inflation molding is preferably 1.0 to 2.3 and the drawdown ratio is 20 to 60. Easy to cut can be realized.

The draw down ratio in the inflation method corresponds to the ratio of the line speed V _L (m / min) to the die exit velocity V ₀ (m / min), and is calculated by V _L / V ₀ . The blow ratio corresponds to the ratio of the diameter D0 of the die to the final diameter D _L of the bubble, and is calculated from D _L / D ₀ . In the present invention, the drawdown ratio is 20 to 60, preferably 25 to 50, and more preferably 30 to 40. The blow ratio is preferably 1.0 to 2.3, more preferably 1.1 to 2.0, and still more preferably 1.2 to 1.5. By adjusting these values to the above range, the resin discharged from the die is dominantly stretched in the flow direction, and it becomes easy to develop excellent tearability and straight tearability.

  In the inflation method, the temperature of the extruder and the die is preferably 180 to 220 ° C. The diameter of the die is preferably 100 to 1200 mm, more preferably 100 to 800 mm, and still more preferably 150 to 500 mm. The lip opening degree of the die is preferably 0.5 to 5 mm, more preferably 1.5 to 4.5 mm, and still more preferably 2.0 to 4.0 mm. The ejection amount is preferably 10 to 400 kg / h, more preferably 20 to 300 kg / h, and still more preferably 50 to 250 kg / h. The line speed varies depending on the diameter of the die, the blow ratio, and the discharge amount, but is preferably 10 to 150 m / min, and more preferably 20 to 100 m / min.

[Retort packaging material]
When the sealant film of the present invention is used as a packaging material for retort, another substrate film can be used by laminating it on the outer layer (A) side surface of the sealant film. The other substrate film is not particularly limited, but it is preferable to use a plastic substrate, particularly a biaxially stretched resin film, from the viewpoint of easily exhibiting the effects of the present invention. Moreover, in the case of the application which does not require transparency, it can also be used combining aluminum foil.

  As a stretched resin film, for example, co-extrusion using a biaxial layer of polyester (PET), biaxially stretched polypropylene (OPP), biaxially stretched polyamide (PA), ethylene vinyl alcohol copolymer (EVOH) as a central layer Biaxially oriented polypropylene, biaxially oriented ethylene vinyl alcohol copolymer (EVOH), alumina vapor deposited PET, silica vapor deposited PET, alumina-silica binary vapor deposited PET, silica vapor deposited PA, alumina vapor deposited PA, and the like. These may be used alone or in combination.

  As a method of bonding the sealant film of the present invention and various stretched base films, two processing methods are mainly used. One is applying the anchor coating agent to the sealant film of the present invention or the laminate surface of the base film as required, and heating and melting a polymer film (polyethylene, polypropylene, etc.) with the sealant film of the present invention and the base It is an extrusion laminating method in which a thin film is extruded, pressed and laminated between laminated surfaces of a material film. The other is a dry lamination method in which the sealant film of the present invention and the substrate film are pressure bonded and laminated after applying an adhesive to the laminate surface of the substrate film, but when used for retort packaging, the dry lamination method preferable.

  Adhesives for lamination are generally cured with a polyol / isocyanate, and are often used for high-performance applications such as retort applications. Also, conventionally, a combination of an aluminum foil and a sealant film has been generally used, but various transparent vapor deposition films are commercially available, and in view of the demand for improving the visibility of the contents, Bonding of sealant films is also increasing.

  Examples of the polyol used for the adhesive for lamination include the polyol itself described later, or a polyester polyol obtained by reacting the polyol and a polycarboxylic acid described later, or ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, Ethylene oxide, propylene oxide, butylene using compounds having two active hydrogen atoms such as trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and the like as an initiator Examples thereof include polyethers obtained by addition polymerization of monomers such as oxides, styrene oxides, 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 Glycols such as 2,4-cyclohexanedimethanol, triethylene glycol, polycaprolactone diol, dimer diol, bisphenol A and hydrogenated bisphenol A 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 with compounds having two active hydrogen atoms such as trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and the like as an initiator Examples thereof 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, and 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 and ester-forming derivatives of these dihydroxycarboxylic acids, dimer acids, etc. And polybasic acids of

  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 Polyisocyanates such as 3- (isocyanatomethyl) cyclohexane, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, adducts of these polyisocyanates, burettes of these polyisocyanates, or polyisocyanates of these polyisocyanates The derivative (modification thing) of polyisocyanate, such as an isocyanurate body, etc. are mentioned.

  Moreover, you may use what reacted the said isocyanate and the said polyol by the mixing ratio used as an excess of an isocyanate group.

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

  The packaging material of the present invention realizes the good sealability and the good tearability by the suitable tearability by the composition which makes the above-mentioned sealant film a sealant and laminates the substrate film on the outer layer (A) side of the sealant film concerned. it can. Moreover, since suitable heat resistance and tear resistance can be realized, fusion between the inner layers (C) to be a heat seal layer and unevenness in appearance can be suppressed even during high-temperature sterilization treatment. For this reason, the packaging material formed by laminating the sealant film of the present invention with various substrates can be suitably applied as a packaging material for retort food.

  The packaging material of the present invention can be suitably used as a packaging bag by forming it into various shapes such as a flat bag type, a self-standing packaging bag (standing pouch) type, a tube type and the like. Specifically, for example, one film-like packaging material is folded so that the sealant layers face each other, or two film-like packaging materials of the present invention are stacked so that the sealant layers face each other, The peripheral edge can be heat-sealed and made into a retort pouch etc. (retort pouch). Moreover, you may provide the opening start parts, such as a V notch and an I notch, as needed.

  The packaging material of the present invention and a packaging bag for retort food using the packaging material can be suitably used for packaging food requiring treatment under high temperature hot water conditions such as boiling and retort sterilization, for example, curry, It can be suitably applied to various retort food packaging applications such as stew, soup, cooking sauce and the like.

Example 1
The following resin was used as a resin component which forms each layer of an outer layer, an intermediate | middle layer, and an inner layer, and the resin mixture which forms each layer was adjusted. The mixtures were each fed to three extruders and melted at 250.degree. The molten resin is supplied to an air-cooling inflation co-extrusion multilayer film manufacturing apparatus (die temperature: 200 ° C.) equipped with a spiral-type three-layer die and co-melt extrusion is performed, and the layer configuration of the film is outer layer / middle With a three-layer structure of layer / inner layer, a laminated film with a total thickness of 60 μm, in which the thickness ratio (%) of each layer is 30/40/30, was obtained. The blow ratio at molding was 1.3, and the draw down ratio was 30.

Outer layer: MFR 0.5 g / 10 min (190 ° C., 21.18 N), linear low density polyethylene having a density of 0.944 g / cm ³ (hereinafter referred to as “LLDPE (1)”)
Intermediate layer: A norbornene copolymer (hereinafter referred to as "COC") 30 of LLDPE (1) 70 mass%, glass transition temperature (Tg) 78 ° C, MFR 10g / 10 minutes (230 ° C, 21.18N) 30 Mass% resin mixture inner layer: LLDPE (1) 50 mass%, MFR 1 g / 10 min (190 ° C., 21.18 N), density 0.960 g / cm ³ high density polyethylene (hereinafter referred to as “HDPE”) 50 mass % Mixed resin.

(Example 2)
A laminated film was obtained in the same manner as in Example 1 except that the blow ratio was 1.5 and the draw down ratio was 27.

(Example 3)
A laminated film was obtained in the same manner as in Example 1 except that the blow ratio was 1.8 and the draw down ratio was 23.

(Example 4)
A laminated film was obtained in the same manner as in Example 1 except that the thickness ratio (%) of the outer layer / intermediate layer / inner layer was 40/25/35, the blow ratio was 1.2, and the drawdown ratio was 35.

(Example 5)
A laminated film was obtained in the same manner as in Example 1 except that the thickness ratio (%) of the outer layer / intermediate layer / inner layer was 35/30/35.

(Example 6)
A laminated film was obtained in the same manner as in Example 2 except that the resin components used for the outer layer and the inner layer were as follows.
Outer layer: 60% by mass of linear low density polyethylene (hereinafter referred to as “LLDPE (2)”) having a MFR of 0.9 g / 10 min (190 ° C., 21.18 N) and a density of 0.929 g / cm ³ , and HDPE 40 Mixed resin of mass% Inner layer: mixed resin of 50 mass% of LLDPE (2) and 50 mass% of HDPE.

(Example 7)
A precision film was obtained in the same manner as in Example 2, except that LLDPE (2) was used as the resin component used for the outer layer and the inner layer.

(Example 8)
A laminated film was obtained in the same manner as Example 2, except that 70% by mass of LLDPE (2) and 30% by mass of COC were used as resin components used for the intermediate layer.

(Comparative example 1)
A laminated film was obtained in the same manner as in Example 1 except that the blow ratio was 2.5 and the draw down ratio was 15.

(Comparative example 2)
A laminated film was obtained in the same manner as in Example 2 except that LLDPE (1) was used as the resin component used for the intermediate layer.

(Comparative example 3)
The resin components for forming the outer layer, the intermediate layer and the inner layer were the same as in Example 1, and these resin mixtures were supplied to three extruders and melted at 250 ° C. The molten resin is supplied to a co-extrusion multilayer film production apparatus (feed block and T die temperature: 250 ° C.) of T-die / chill roll method having a feed block, and co-melt extrusion is performed to make the layer structure of the film an outer layer. A sealant film having a total thickness of 50 μm and a thickness ratio of each layer of 25/50/25% was obtained with a three-layer structure of / intermediate layer / inner layer.

  The following evaluation was performed about the laminated film (sealant film) obtained by the said Example and comparative example. The obtained results are shown in the following table.

(1) Normalized molecular orientation MORc
About each film of an Example and a comparative example, normalization molecular orientation MORc was measured by Oji Scientific Instruments Ltd. microwave system molecular orientation meter MOA-2000. The reference thickness tc was set to 60 μm.

(2) Tear strength According to JIS K 7128-1 (Trouser method), the tear strength in the flow direction was measured in a constant temperature chamber at 23 ° C. and 50% Rh.
1 N or less: ((excellent in tearability)
More than 1 N: x (poor to tear)

(2) Straight cutting property Using a test piece with a length of 150 mm in the flow direction of the film and 50 mm in the width direction, insert a 15 mm width cut at 10 mm in the center in the width direction, and the width of the tip of the cut (W ₀ ). A polyester sheet of 0.3 mm in thickness, 15 mm in width and 160 mm in length prepared in advance is taped to the tip of the incision. Affix the attached polyester sheet in the direction of 180 °, attach the test piece from which the notch on the opposite side to the tip is removed to a tensile tester, tear 100 mm at a speed of 300 mm / min, width at the end point (W ₁ ). At this time, the retention rate was determined from the following equation, and used as an index of straight cutability.
Retention rate [%] = W ₁ / W ₀ × 100
100 ± 10%: ((excellent straight cut performance)
More than 100 ± 10%: x (Straightness of straightness is poor)

(3) Sealing strength A polyester based adhesive is coated on a 25 μm thick biaxially stretched polyamide film using a wire bar so that the coating thickness is 3.5 g / m ² . After drying the adhesive, a sealant film was laminated and dried at 40 ° C. for 24 hours to obtain a laminate film for heat seal test. Using the obtained film, a test piece heat-sealed under the conditions of 160 ° C., 0.2 MPa and 1 second was prepared, and heat treatment was performed at 121 ° C. for 30 minutes using an autoclave. The test piece after the heat treatment was cut into a width of 15 mm, and the seal strength was measured with a tensile tester. If it is 40 N / 15 mm or more, it can usually be used.

(4) Inner surface fusion bonding A laminated film was obtained in the same manner as (3). The obtained film seals were overlapped, and heat treatment was performed at 121 ° C. for 30 minutes using an autoclave. The test piece after the heat treatment was cooled to normal temperature and then cut into a width of 15 mm, and the peel strength was measured with a tensile tester. Those having a peel strength of 1 N / 15 mm or less were evaluated as those having excellent heat resistance.

(5) Unevenness in appearance A laminated film was obtained in the same manner as in (3). Using the obtained film, the bag was processed to have an inner size of 100 mm × 150 mm (heat seal width 10 mm), and 200 ml of water was sealed. After the bag-formed product in which water was sealed was retorted at 121 ° C. for 30 minutes, the state of the appearance unevenness was visually evaluated.

  As apparent from the above table, the sealant films of the present invention of Examples 1 to 8 had tear strength which is easy to tear and good straight cut properties. The sealant films of Examples 1 to 6 all had a peel strength of 1 N / 15 mm or less in the evaluation of inner surface fusion. Furthermore, in the sealant films of Examples 1 to 6, the appearance unevenness was not visually recognized even in the appearance evaluation. On the other hand, the sealant film of the comparative example did not have tearability and favorable straight-line cuttability, and did not have suitable tearability.

Claims (15)

It comprises a laminated film in which an outer layer (A), an intermediate layer (B) and an inner layer (C) are laminated,
The outer layer (A) and the inner layer (C) contain a polyethylene resin,
The intermediate layer (B) contains a linear low density polyethylene (b1) and a cyclic olefin resin (b2), and the cyclic olefin resin (b2) in the resin component contained in the intermediate layer (B) The content is 20 to 40% by mass,
A sealant film having a standardized molecular orientation MORc value of 1.025 or more when the reference thickness measured by a microwave type molecular orientation meter is 60 μm.   The sealant film according to claim 1, wherein the thickness of the intermediate layer (B) is 10 to 50% of the total thickness of the laminated film. The average density of the resin component in the outer layer (A) and the inner layer (C) is 0.940 g / cm ³ or more, and the density of the linear low density polyethylene (b1) is 0.937 g / cm ³ or more The sealant film according to claim 1 or 2.   The sealant film according to any one of claims 1 to 3, wherein the content of the linear low density polyethylene (b1) in the resin component contained in the intermediate layer (B) is 60 to 80% by mass.   The sealant film according to any one of claims 1 to 4, wherein the glass transition temperature of the cyclic olefin resin (b2) is 140 ° C or less.   The sealant film according to any one of claims 1 to 5, which has a total thickness of 20 to 150 μm.   The MFR of the linear low density polyethylene (b1) is 0.1 to 20 g / 10 min, and the MFR of the cyclic olefin resin (b2) is 0.2 to 17 g / 10 min. Sealant film described in.   A packaging material using the sealant film according to any one of claims 1 to 7. A method for producing a sealant film comprising a laminated film in which an outer layer (A), an intermediate layer (B) and an inner layer (C) are laminated by a coextrusion inflation method,
The outer layer resin forming the outer layer (A) and the inner layer resin forming the inner layer (C) contain a polyethylene resin, and the intermediate layer resin forming the intermediate layer (B) has a linear low density Content of the said cyclic olefin resin (b2) in the resin component contained in polyethylene resin (b1) and cyclic olefin resin (b2) and contained in resin for said intermediate | middle layers is 20-40 mass%,
A method of manufacturing a sealant film characterized by coextrusion inflation molding with a blow ratio of 1.0 to 2.3 and a drawdown ratio of 20 to 60.   The method for producing a sealant film according to claim 9, wherein the MORc value of the laminated film is 1.025 or more.   The method for producing a sealant film according to claim 9 or 10, wherein the thickness of the intermediate layer (B) of the laminated film is 10 to 50% of the total thickness of the laminated film. The average density of the resin component in the outer layer (A) and the inner layer (C) is 0.940 g / cm ³ or more, and the density of the linear low density polyethylene (b1) is 0.937 g / cm ³ or more The manufacturing method of the sealant film in any one of Claims 9-11.   The method for producing a sealant film according to any one of claims 9 to 12, wherein the glass transition temperature of the cyclic olefin resin (b2) is 140 ° C or less.   The method for producing a sealant film according to any one of claims 9 to 13, wherein the total thickness is 20 to 150 m.   The MFR of the linear low density polyethylene (b1) is 0.1 to 20 g / 10 min, and the MFR of the cyclic olefin resin (b2) is 0.2 to 17 g / 10 min. The manufacturing method of the sealant film as described in.