KR20190139833A - Sealant Films & Packaging - Google Patents

Abstract

The outer layer, the intermediate layer, and the inner layer are laminated films, the outer layer and the inner layer contain a polyethylene resin, the middle layer contains a linear low-density polyethylene and a cyclic olefin resin, the above-mentioned resin component in the intermediate layer Content of cyclic olefin resin is 20-40 mass%, and normalized molecular orientation MORc value when the reference thickness measured with a microwave system molecular orientation system is 60 micrometers is 1.025 or more, The outstanding tear property And straight cut property can be realized, and the inner surface fusion and appearance irregularity of the packaging material at the time of high temperature processing can be suppressed.

Description

Sealant Films & Packaging

This invention relates to the sealant film used for retort packaging etc. which can be sterilized by heating, pressurization, cooking, etc. in the state which packaged food, etc., and the packaging material using the said sealant film.

As food packaging materials, flexible packaging using plastic materials has been used all over the world, and is showing an increasing trend with expansion to emerging countries. Among these, retort foods that have been pressurized and heated to sterilization (retort sterilization) at a high temperature are expected to increase in demand in the food packaging market in the future due to their convenience. The retort food can be distributed at room temperature, and in addition to ease of eating, can be easily handled in distribution, and expansion to regions where cold chain development is insufficient is expected.

When eating a retort food, it is common to heat by boiling in hot water, and after heating, a film is tear-opened from the notch provided in the upper end of a packing stand. For this reason, two tear property is calculated | required by the resin film used for retort packaging. As a retort film having a tear property, for example, a propylene-based film is disclosed in which a birefringence is controlled to a specific range by using a resin in which a low-crystalline ethylene-based elastomer is blended in a propylene-ethylene block copolymer ( See Patent Document 1).

Moreover, as a packaging material which has a cutability, it is a packaging material used for the soft bag filled with chemical liquids, such as a physiological saline solution and electrolyte solution, The intermediate | middle layer containing cyclic olefin resin and linear low-density polyethylene resin, and linear form The packaging material which has an inner layer and an outer layer of a low density polyethylene resin is disclosed (refer patent document 2).

Japanese Patent Laid-Open No.2011-162667 Japanese Patent Laid-Open No. 2009-172902

In the propylene-based film which promoted the above-mentioned birefringence, a decrease in tear strength was confirmed by improving the stiffness of the film, but the control of tearing directionality was not sufficient, and an improvement in straight cut property that was to be teared straight was required. . Moreover, in heavy materials for business use, distribution in a cold district, etc., the impact resistance is not enough in the packaging material which uses an ethylene-propylene copolymer as a sealant, and it may cause a crash accident.

Although the packaging material used for the said soft bag has a cutability and a straight cut property, the improvement of the cut property was calculated | required in application to a retort use.

An object of the present invention is to provide a sealant film and a packaging material which have favorable band resistance and are excellent in tear resistance and straight cut property.

Moreover, in this invention, it is a subject to provide the sealant film which has suitable sealability in addition to the said subject.

Moreover, in this invention, in addition to the said subject, an object of this invention is to provide the sealant film which does not generate | occur | produce the inner surface fusion of a packaging material, or an external appearance nonuniformity.

The present invention comprises a laminated film in which an outer layer (A), an intermediate layer (B) and an inner layer (C) are laminated, and the outer layer (A) and the inner layer (C) contain a polyethylene resin, and the intermediate layer (B) A linear low density polyethylene (b1) and cyclic olefin resin (b2) are contained, and content of the said cyclic olefin resin (b2) in the resin component contained in the said intermediate | middle layer (B) is 20-40 mass%, and is a microwave system The said subject is solved by the sealant film whose normalized molecular orientation MORc value when the reference thickness measured with a molecular orientation system is 60 micrometers is 1.025 or more.

Moreover, this invention is a method of manufacturing the sealant film which consists of laminated | multilayer film which laminated | stacked the outer layer (A), the intermediate | middle layer (B), and the inner layer (C) by co-extrusion inflation method, The outer layer which forms the said outer layer (A) The resin for the inner layer forming the resin and the inner layer (C) contains a polyethylene resin, and the resin for the middle layer forming the intermediate layer (B) is a linear low density polyethylene (b1) and a cyclic olefin resin (b2). It is contained, The content of the said cyclic olefin resin (b2) in the resin component contained in the said resin for intermediate | middle layers is 20-40 mass%, The blow ratio of 1.0-2.3 is coextrusion-inflation-molded by the drawdown ratio of 20-60, The said subject is solved by the manufacturing method of a sealant film.

Since the sealant film of this invention has favorable tearing property and straight cut property by the said structure, the packing stand using the sealant film of this invention is hard to produce the overflow and scattering of the content at the time of opening or after opening starts. In particular, even when applied to retort packaging applications, it is possible to cut with simple and suitable straightness. In addition, the favorable waveband resistance, in particular, the favorable waveband resistance under low temperature can be realized, and it has a favorable distribution aptitude.

Moreover, while the sealant film of this invention realizes favorable thermal property, it is easy to implement | achieve the packaging material which does not generate | occur | produce inner surface fusion or external appearance nonuniformity at the time of high temperature processing, such as a retort sterilization process. For this reason, the sealant film of this invention can be applied suitably to packaging materials for high temperature processing, such as a retort food packaging material which requires high temperature sterilization. Moreover, since the sealant film of this invention is also easy to implement suitable sealing property, it is suitable for these packaging materials use.

The sealant film of the present invention consists of a laminated film in which an outer layer (A), an intermediate layer (B) and an inner layer (C) are laminated in order, and the outer layer (A) and the inner layer (C) contain a polyethylene resin, 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), and the cyclic olefin resin in the resin component contained in the intermediate layer (B). It is a sealant film whose content of (b2) is 20-40 mass%. Moreover, the normalized molecular orientation MORc value when the reference thickness measured with a microwave system molecular orientation system is 60 micrometers is 1.025 or more.

[Outer layer (A)]

The outer layer (A) of the sealant film of the present invention contains a polyethylene resin. As said polyethylene-type resin, polyethylene resins, 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), and ethylene- Vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-maleic anhydride Ethylene-based copolymers such as acid copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA); Furthermore, the ionomer of an ethylene-acrylic acid copolymer, the ionomer of an ethylene-methacrylic acid copolymer, etc. can be illustrated. These polyethylene resins may be used independently and may mix and use 2 or more types. Among these, since favorable impact resistance is easy to be obtained, ultra low density polyethylene, linear low density polyethylene, low density polyethylene, linear medium density polyethylene can be used preferably, and linear low density polyethylene is especially preferable. Moreover, it is also preferable to use high density polyethylene (HDPE) in combination with these medium and low density polyethylene.

As the linear low density polyethylene, an ethylene monomer is used as a main component by a low pressure radical polymerization method using a single site catalyst, and α-olefins such as butene-1, hexene-1, octene-1,4-methylpentene are used as comonomers. It is copolymerized. As 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 which is 1-18 mol%.

As said single-site catalyst, various single-site catalysts, such as a metallocene catalyst system, such as a combination of the metallocene compound of periodic table IV or a group 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 point, the molecular weight distribution of the resin obtained becomes sharper as compared with the multisite catalyst where the active point is nonuniform. Since resin of the physical property which is excellent in stability and impact resistance is obtained, it is preferable.

In the outer layer (A), since it is easy to obtain suitable impact resistance, it is preferable to contain 60 mass% or more of polyethylene-type resin with respect to the resin component whole quantity which forms the said layer, and it is more preferable to contain it at 80 mass% or more. And it is more preferable to contain in 90 mass% or more. Especially, it is preferable to contain only polyethylene-type resin as a resin component, and to make 60 mass% or more in the said resin component into linear low density polyethylene, It is more preferable to set it as 80 mass% or more, and to set it as 90 mass% or more More preferred.

In addition, in the outer layer (A), you may use together other resin of the said polyethylene-type resin in the range which does not impair the effect of this invention. As other resin species which can be used together, polyolefin resin other than the said polyethylene-type resin etc. can be illustrated, for example, A propylene homopolymer, a propylene ethylene copolymer, a propylene- butene-1 copolymer, a propylene- Polypropylene resin, such as an ethylene butene-1 copolymer and a metallocene catalyst polypropylene, can be illustrated.

When using these other resin, it is preferable to set it as 40 mass% or less in the resin component contained in an outer layer (A), It is more preferable to set it as 20 mass% or less, It is more preferable to set it as 10 mass% or less. . Moreover, although a minimum in particular is not restrict | limited, What is necessary is just to use suitably with content of 1 mass% or more according to a desired characteristic.

As for the outer layer (A) used for the sealant film of this invention, it is preferable that the average density of the resin component used in the layer is 0.940 g / cm <3> or more, More preferably, it is a layer which is 0.940-0.945 g / cm <3>. By making the average density of a resin component into the said range, the appearance nonuniformity at the time of high temperature processing, such as a retort sterilization process, can be suppressed suitably. When the resin used for the said layer is resin a, resin b, resin c ..., the said average density of resin which uses the density of these resin in d _a , d _b , d _c ... When the mass is W _a , W _b , W _c ..., (d _a W _a + d _b W _b + d _c W _c ...) / (W _a + W _b + W _c ...) Is the density calculated.

Although the density of each resin used for an outer layer (A) will not be restrict | limited especially if the average density of the resin component to be used becomes the said range, In polyethylene-type resin, it is preferable that it is 0.880 g / cm <3> or more, and is 0.920g / cm <3> or more It is more preferable, and it is especially preferable that it is 0.940-0.950g / cm <3>. In addition, it is preferable to use 0.920 g / cm <3> or more also about other resin.

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

[Middle layer (B)]

The intermediate | middle layer (B) of the sealant film of this invention contains linear low density polyethylene (b1). By containing the said linear low density polyethylene, it becomes easy to suppress suitably the external appearance nonuniformity at the time of the retort sterilization process at the time of high temperature treatment with favorable impact resistance. Since the density of linear low density polyethylene (b1) is easy to suppress an appearance nonuniformity especially suitably, Preferably it is 0.937g / cm <3> or more, More preferably, it is 0.940g / cm <3> or more, More preferably, it is 0.940-0.945g / 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 an intermediate | middle layer (B), it is more preferable that it is a layer of 0.940-0.945 g / cm <3>.

The MFR of the 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), more preferably 0.5 to 5 g / 10 minutes (190 ° C., 21.18 N). If MFR is this range, it is preferable at the point which is excellent in compatibility with cyclic olefin resin (b2), and favorable film-forming property is acquired in various multilayer film-forming methods.

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

By containing cyclic olefin resin (b2) in the intermediate | middle layer (B) of the sealant film of this invention, excellent di tear property and straight cut property can be implement | achieved. As said cyclic olefin resin (b2), a norbornene-type polymer, a vinyl alicyclic hydrocarbon polymer, a cyclic conjugated diene polymer, etc. are mentioned, for example. Among these, norbornene-type polymers are preferable. In addition, as a norbornene-type polymer, the norbornene-type copolymer which copolymerizes the ring-opening polymer of a norbornene-type monomer (henceforth "COP"), norbornene-type monomer, and olefins, such as ethylene (henceforth "COC"), ), And the like. Moreover, the hydrogenated substance of COP and COC is also especially preferable. Moreover, as for the weight average molecular weight of cyclic olefin resin, 5,000-500,000 are preferable, More preferably, it is 7,000-300,000.

The norbornene-based monomer which is a norbornene-based polymer and a raw material is an alicyclic monomer having a norbornene ring. As such norbornene-based monomers, for example, norbornene, tetracyclododecene, ethylidene norbornene, vinyl norbornene, ethylidene tetracyclododecene, dicyclopentadiene, dimethanotetrahydroflu Orene, phenyl norbornene, methoxycarbonyl norbornene, methoxycarbonyl tetracyclododecene and the like. These norbornene-type monomers may be used independently and may use 2 or more types together.

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

It is preferable that it is 20-40 mass% in the resin component contained in an intermediate | middle layer (B), and, as for content of cyclic olefin resin (b2) contained in an intermediate | middle layer (B), it is more preferable that it is 25-35 mass%. By making content of cyclic olefin resin (b2) into the said range, favorable tearing property and straight cut property can be implement | achieved, without impairing impact resistance.

Moreover, it is preferable that the glass transition temperature of cyclic olefin resin (b2) used in an intermediate | middle layer (B) is 140 degrees C or less, It is more preferable that it is 50-140 degreeC, It is still more preferable that it is 70-120 degreeC. By using the thing of the said glass transition temperature as cyclic olefin resin (b2), favorable heat resistance and rigidity are easy to be obtained, and also the band resistance to fall etc. becomes easy to be improved. Moreover, favorable compatibility becomes easy to be obtained and it becomes easy to suppress external appearance nonuniformity. Glass transition temperature (Tg) is a value obtained by measuring by DSC.

MFR of cyclic olefin resin (b2) is 0.2-17g / 10min (230 degreeC, 21.18N), Preferably it is 3-15g / 10min (230 degreeC, 21.18N), More preferably, it is 5-13g / 10 minutes (230 ° C., 21.18 N). If MFR is this range, it is preferable at the point which is excellent in compatibility with linear low density polyethylene (b1), and favorable film-forming property is acquired in various multilayer film-forming methods.

As a commercial item which can be used as cyclic olefin resin used for this invention, as a ring-opening polymer (COP) of a norbornene-type monomer, "ZEONOR" by Nihon Zeon Co., Ltd. is mentioned, for example. As a norbornene-type copolymer (COC), "Apel" by Mitsui Chemical Co., Ltd., "TOPAS" by polyplastics company, etc. are mentioned, for example.

Although it is also preferable to contain only the said linear low density polyethylene (b1) and cyclic olefin resin (b2) as a resin component in an intermediate | middle layer (B), resin other than these resin components in the range which does not impair the effect of this invention. You may use together. As another resin type which can be used together, the polyethylene-type resin, polypropylene resin, etc. which were illustrated by the said outer layer (A) can be illustrated, for example.

When using these other resin, 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. Moreover, although a minimum in particular is not restrict | limited, What is necessary is just to use suitably with content of 1 mass% or more according to a desired characteristic.

[Inner layer (C)]

The inner layer (C) in the sealant film of the present invention is a layer containing polyethylene-based resin, and preferably a layer whose average density of the resin component in the layer is 0.940 g / cm 3 or more. The said inner layer (C) is a layer used as the heat seal layer of a sealant film.

Polyethylene resin used for inner layer (C), resin which can be used together with the said polyethylene resin, etc. can illustrate the same thing as the said outer layer (A), and a preferable thing is also the same. In addition, the range similar to the said outer layer (A) can also be illustrated as a preferable range also about content of the said polyethylene-type resin and other resin, and the density and average density of the resin component in an inner layer.

Moreover, in inner layer (C), it is also preferable to use high density polyethylene (HDPE) 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. When using medium and low density polyethylene together with high density polyethylene, it is thing to make content of the medium and low density polyethylene in the resin component used for an inner layer (C) 40-80 mass%, and content of high density polyethylene 20-60 mass%. It is preferable to make content of medium and low density polyethylene 45-75 mass%, and content of high density polyethylene to 25-55 mass%.

[Seal 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 laminated in order. By the said structure, the sealant film of this invention can implement | achieve the packaging material which has favorable bi-tearability and straight cut property, and does not generate | occur | produce inner surface fusion or external appearance nonuniformity at the time of high temperature processing, such as a retort sterilization process. In addition, it is easy to realize suitable sealability and breaking resistance, and therefore, it is suitable for retort packaging materials.

The sealant film of the present invention has a standardized molecular orientation MORc value of 1.025 or more, preferably 1.030 or more, and more preferably 1.035 or more when the reference thickness measured by a microwave system molecular alignment system is 60 µm. In addition, an upper limit is although it does not restrict | limit especially, Preferably it is 1.20 or less, More preferably, it is 1.080 or less. In this invention, when the MORc value of a sealant film is made into the said range, the outstanding tearing property and the straight cut property can be implement | achieved with favorable breaking resistance.

The MORc value is a value indicating the degree of molecular orientation and is measured by the following measurement method.

In the microwave resonant waveguide of the well-known microwave system molecular orientation system, it arrange | positions so that the said sample surface (film surface) may be perpendicular to the advancing direction of a microwave. In the state where the microwaves deflected in one direction are continuously irradiated with the sample, the sample is rotated from 0 to 360 ° in a plane perpendicular to the traveling direction of the microwave, and the molecular orientation degree MOR is measured by measuring the microwave intensity transmitted through the sample. Obtain

The normalized molecular orientation MORc in this embodiment is a MOR value when the reference thickness is tc, and can be obtained by the following formula.

 MORc = (tc / t) × (MOR-1) +1

(tc: reference thickness to be corrected, t: sample thickness)

Here, it shows that it is an isotropic film as MORc value approaches 1.000.

The standardized molecular orientation MORc can be measured at a resonance frequency near 4 GHz by a known molecular alignment system, for example, a microwave system molecular alignment system MOA-2000A, MOA-2012A, etc. manufactured by Ojigaisokuki Co., Ltd. have.

Although the thickness of the sealant film of this invention may be adjusted suitably according to the use and the aspect to be used, it is 20-150 micrometers in total from a viewpoint of heat resistance in a packaging use, the band resistance at the time of distribution, heat sealability, etc. It is preferable and it is more preferable that it is 40-100 micrometers.

As thickness ratio of each layer, it is preferable that the thickness ratio of outer layer (A) is 10 to 40% of range of the total thickness of a sealant film from a viewpoint of sealing property, tearing property, and lamination property, and it is more preferable that it is 15 to 30%. Do. Moreover, it is preferable that it is 10 to 40% of range, and, as for the thickness ratio of an inner layer (C), it is more preferable that it is 15 to 30% of range.

Moreover, as thickness ratio of an intermediate | middle layer (B), it is preferable that it is 10 to 80%, It is more preferable that it is 15 to 60%, It is especially preferable that it is 20 to 50%. Moreover, in the sealant film of this invention, even if it is set as the case where the thickness ratio of the intermediate | middle layer (B) is low (for example, 40% or less, more preferably 30% or less), suitable cut property can be implement | achieved, A cut sealant film can be obtained in low cost.

As specific thickness, as thickness of an outer layer (A), it is preferable that it is 2-60 micrometers, and it is more preferable that it is 3-45 micrometers. It is preferable that it is 4-120 micrometers, and, as for the thickness of an intermediate | middle layer (B1), it is more preferable that it is 8-100 micrometers. It is preferable that it is 2-60 micrometers, and, as for the thickness of an inner layer (C), it is more preferable that it is 3-45 micrometers.

Although the sealant film of this invention is a laminated | multilayer film in which the said outer layer (A), the intermediate | middle layer (B), and the inner layer (C) were laminated | stacked in order, it is a gas barrier layer or this in the range which does not impair the effect of this invention between the said layers. You may provide other arbitrary layers, such as an contact bonding layer. Moreover, it is preferable that the average density of the resin component in the layer of all layers is 0.940 g / cm <3> or more, and, as for the sealant film of this invention, it is more preferable that it is a layer of 0.940-0.945 g / cm <3>. 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 this invention, you may mix | blend various additives in the range which does not impair the effect of this invention. Examples of the additives include antioxidants, weather stabilizers, antistatic agents, antifogging agents, antiblocking agents, lubricants, nucleating agents, pigments, and the like.

[Manufacturing method]

As a manufacturing method of the sealant film of this invention, the resin (including the resin mixture containing 2 or more types of resin and additives) used for each layer of a multilayer film is heated and melted with a separate extruder, respectively, After lamination | stacking in a molten state by methods, such as an extrusion multilayer dice method and a feed block method, the co-extrusion method shape | molded in a film form by the inflation method is mentioned. This coextrusion method is preferable because it is possible to adjust the ratio of the thickness of each layer relatively freely, and because a film excellent in hygiene and excellent in cost-effectiveness is obtained. As the inflation method, an air-cooled inflation method is preferable, and an upward air-cooled inflation method can be used especially preferably. Moreover, it can be set as a multilayer film by using a some extruder and a multilayer circular die. After using these, the cylindrical molten resin is extruded upwards, the cylindrical molten resin is expanded and drawn as needed, and the molten resin is cooled and solidified by air cooling, and then, the desired film is cut and applied. You can get it.

In this invention, since it is easy to obtain the sealant film which has a specific orientation, favorable cutability can be implement | achieved by setting the blow ratio at the time of the said co-extrusion inflation shaping to 1.0-2.3, and the drawdown ratio 20-60.

The drawdown ratio in the inflation method corresponds to the ratio between the line speed V _L (m / min) and the die exit speed V ₀ (m / min), and is calculated by V _L / V ₀ . In addition, corresponding to the blow Sembilan, the ratio of the diameter D ₀ and the end of the bubble diameter D _L of the die, and is calculated from D _L / D _0. In this invention, although the drawdown ratio is 20-60, it is preferable to set it as 25-50, and it is more preferable to set it as 30-40. Moreover, it is preferable to set it as 1.0-2.3, it is more preferable to set it as 1.1-2.0, and it is more preferable to set it as 1.2-1.5. By adjusting these values in the above range, the resin discharged from the die is predominantly elongated in the flow direction, and excellent tearing property and straight tearing property are easily expressed.

In the inflation method, it is preferable that the temperature of an extruder and a die is 180-220 degreeC. It is preferable that it is 100-1200 mm, it is more preferable that it is 100-800 mm, and, as for the diameter of dice | dies, it is still more preferable that it is 150-500 mm. It is preferable that the lip opening degree of a dice is 0.5-5 mm, It is more preferable that it is 1.5-4.5 mm, It is more preferable that it is 2.0-4.0 mm. It is preferable that discharge amount is 10-400Kg / h, It is more preferable that it is 20-300Kg / h, It is more preferable that it is 50-250Kg / h. The line speed is different depending on the diameter of the dice, the blow ratio, and the discharge amount, but is preferably 10 to 150 m / min, more preferably 20 to 100 m / min.

[Packaging Material for Retort]

When using the sealant film of this invention as a packaging material for retorts, it can bond and use another base film on the outer layer (A) side surface of a sealant film. Although it does not specifically limit as another base film, It is preferable to use a plastic base material, especially the biaxially stretched resin film from a viewpoint which expresses the effect of this invention easily. Moreover, in the case of the use which does not require transparency, you can use combining aluminum foil.

As the stretched resin film, for example, a biaxially stretched polyester (PET), a biaxially stretched polypropylene (OPP), a biaxially stretched polyamide (PA), or an ethylene vinyl alcohol copolymer (EVOH) as a co-extrusion biaxial Stretched polypropylene, biaxially stretched ethylene vinyl alcohol copolymer (EVOH), alumina vapor deposition PET, silica vapor deposition PET, alumina silica double vapor deposition PET, silica vapor deposition PA, alumina vapor deposition PA, etc. are mentioned. You may use these individually or in combination.

Two processing methods are mainly used as a method of bonding the sealant film of this invention and the various extended base films. One apply | coats an anchor coat agent to the laminate surface of the sealant film of this invention or the base film as needed, and laminates the heat-melted polymer film (polyethylene, polypropylene etc.) of the sealant film of this invention and a base film It is an extrusion lamination method which extrudes, compresses, and laminate | stacks in thin film form between surfaces. The other is a dry lamination method of compressing and laminating the sealant film and the base film of the present invention after applying an adhesive to the laminate surface of the base film, but when using for retort packaging, the dry lamination method is preferred.

The adhesive for lamination is generally hardened by polyol / isocyanate, and is often used for high-performance applications such as retort applications. Moreover, although bonding of aluminum foil and a sealant film was common in bonding together conventionally, various transparent vapor deposition films are marketed, and bonding of a transparent vapor deposition film and a sealant film also became large from the request of the visibility improvement of the content.

As a polyol used for the adhesive agent for laminations, the polyol itself mentioned later, or the polyester polyol obtained by making a polyol and polycarboxylic acid mentioned later react, or ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, for example And compounds having two active hydrogen atoms such as trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, and neopentylglycol as initiators, such as ethylene oxide, propylene oxide, butylene oxide And polyethers obtained by addition polymerization of monomers such as styrene oxide, epichlorohydrin, tetrahydrofuran and cyclohexylene.

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

Examples of the polycarboxylic acids include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, Terephthalic acid, 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; and polybasic acids such as p-hydroxybenzoic acid, p- (2-hydroxyethoxy) benzoic acid, ester-forming derivatives of these dihydroxycarboxylic acids and dimer acid.

As said polyisocyanate, the organic compound which has at least two isocyanate groups in a molecule | numerator is mentioned, for example. As an organic polyisocyanate, for example, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'- methylene bis (cyclohexyl isocyanate) Polyisocyanates such as lysine diisocyanate, trimethylhexamethylene diisocyanate, 1,3- (isocyanatomethyl) cyclohexane, 1,5-naphthalene diisocyanate and triphenylmethane triisocyanate; And derivatives (modified products) of polyisocyanates such as adducts of these polyisocyanates, biurets of these polyisocyanates, or isocyanurates of these polyisocyanates.

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

In an adhesive, it is preferable that the equivalence ratio polyol / isocyanate of the hydroxyl group equivalent of the said polyol, and the isocyanate equivalent of the said polyisocyanate is 0.5-5.0.

The packaging material of this invention makes the said sealant film a sealant, and it is a structure which laminates a base film on the outer layer (A) side of the said sealant film, and is favorable sealing property and favorable opening property by suitable thermal properties. It can be realized. Moreover, since favorable heat resistance and breakband resistance can be implement | achieved, the fusion and internal appearance nonuniformity of inner layers C used as a heat seal layer can be suppressed also at the time of high temperature sterilization treatment. For this reason, the packaging material formed by laminating | stacking the sealant film of this invention with various base materials can be applied suitably as a packaging material for retort foodstuffs.

The packaging material of this invention can be suitably used as a packaging stand by zipping in various shapes, such as a flat form, a standalone pouch (stand-up pouch) type, and a tube form. Specifically, for example, one sheet of film-shaped packaging material is folded so that the sealant layers face each other, or two sheets of film-shaped packaging material of the present invention are overlapped so that the sealant layers face each other, and the peripheral end thereof is heat-sealed. Can be removed by a packing table (retort pouch) such as retort food. In addition, you may provide opening start parts, such as a V notch and an I notch, as needed.

The packaging material of this invention and the retort food packaging stand using the said packaging material can be used suitably for the packaging of food which requires processing under high temperature hydrothermal conditions, such as a voile and a retort sterilization, For example, curry, stew, soup, It can apply suitably to various retort food packaging uses, such as a cooking sauce.

(Example)

(Example 1)

As a resin component which forms each layer of an outer layer, an intermediate | middle layer, and an inner layer, the resin mixture which forms each layer was adjusted using the following resin, respectively. These mixtures were respectively fed to three extruders and melted at 250 degreeC. The molten resin was supplied to the coextrusion multilayer film manufacturing apparatus (die temperature: 200 degreeC) of the air-cooled inflation method provided with a spiral three-layer die, respectively, and co-melt extrusion was carried out, and the layer structure of a film is an outer layer / an intermediate | middle layer / an inner layer It was a three-layered constitution, and the laminated | multilayer film of 60 micrometers in total thickness whose thickness ratio (%) of each layer is 30/40/30 was obtained. The blow ratio at the time of shaping | molding was 1.3 and the drawdown ratio was 30.

Outer layer: MFR 0.5g / 10min (190 ° C, 21.18N), linear low density polyethylene having a density of 0.944g / cm3 (hereinafter referred to as "LLDPE (1)")

Intermediate layer: 70 mass% of LLDPE (1), 30 mass% of norbornene-type copolymers (henceforth "COC") of glass transition temperature (Tg) 78 degreeC, MFR 10g / 10min (230 degreeC, 21.18N). Resin mixture

Inner layer: 50 mass% of LLDPE (1) mixed resin of 50 mass% of high density polyethylene (henceforth "HDPE") with a density of 0.960 g / cm <3>, MFR 1g / 10min (190 degreeC, 21.18N).

(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, the middle layer, and the 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 | multilayer film was obtained like Example 2 except having set the resin component used for an outer layer and an inner layer below.

Outer layer: 60 mass% of MFR 0.9 g / 10min (190 degreeC, 21.18 N), linear low density polyethylene (henceforth "LLDPE (2)") of density 0.929 g / cm <3>, and mixed resin of 40 mass% of HDPE water

Inner layer: 50 mass% of LLDPE (2), and mixed resin of 50 mass% of HDPE.

(Example 7)

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

(Example 8)

A laminated | multilayer film was obtained like Example 2 except having set the resin component used for an intermediate | middle layer to 70 mass% of LLDPE (2), and 30 mass% of COC.

(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 the resin component used for the intermediate layer was LLDPE (1).

(Comparative Example 3)

As a resin component which forms each layer of an outer layer, an intermediate | middle layer, and an inner layer, it carried out similarly to Example 1, These resin mixtures were respectively supplied to three extruders, and were melted at 250 degreeC. The molten resin is supplied to the co-extrusion multilayer film manufacturing apparatus (feed block and T die temperature: 250 degreeC) of the T die chill roll method which has a feed block, respectively, and co-melt extrusion is carried out, and the layer structure of a film is an outer layer / an intermediate layer. It was a three-layered constitution of / inner layer, and the sealant film of 50 micrometers in total thickness whose thickness ratio of each layer is 25/50/25% was obtained.

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

(1) standardized molecular orientation MORc

About each film of an Example and a comparative example, normalized molecular orientation MORc was measured with the microwave system molecular orientation system MOA-2000 by Ojigaisokukiki Co., Ltd .. Reference thickness tc was set to 60 micrometers.

(2) tear strength

According to JIS K7128-1 (the Trouser method), the tear strength in the flow direction was measured in a constant temperature room at 23 ° C and 50% Rh.

 1N or less: ○ (excellent tearing property)

 1N or more: × (low tearability)

(2) straight cut

Using a test piece having a length of 150 mm in the flow direction of the film and a length of 50 mm in the width direction, a 10 mm 15 mm wide slit is placed in the center of the width direction and the width W ₀ of the tip of the slit is measured. . A polyester sheet having a thickness of 0.3 mm, a width of 15 mm, and a length of 160 mm prepared in advance is attached to the tip of the slit with a tape. Fold the polyester sheet affixed in the 180 ° direction, attach the test piece except the slit portion opposite the tip portion to the tensile tester, tear 100 mm at a speed of 300 mm / min, and change the width W1 of the end point. Actually, At this time, the retention rate was calculated | required from the following formula | equation, and it was set as the index of straight cut property.

Retention rate [%] = W ₁ / W ₀ × 100

 100 ± 10%: ○ (excellent straight cut property)

 More than 100 ± 10%: × (lack of straightness)

(3) seal strength

On the 25-micrometer-thick biaxially stretched polyamide film, a polyester adhesive is apply | coated so that application thickness may be set to 3.5 g / m <2> using a wire bar. The adhesive film was dried, the sealant film was bonded together, and it dried at 40 degreeC for 24 hours, and obtained the laminated film for heat seal tests. Using the obtained film, the test piece heat-sealed on 160 degreeC, 0.2 Mpa, and 1 second conditions was created, and 121 degreeC and 30-minute heat processing were performed using the autoclave. The test piece after heat processing was cut out in 15 mm width, and the seal strength was measured with the tensile tester. If it is 40 N / 15 mm or more, it can use normally.

(4) inner surface fusion

In the same manner as in (3), a laminated film was obtained. The seals of the obtained films were stacked, and heat treatment was performed at 121 ° C. for 30 minutes using an autoclave. After cooling the test piece after heat processing to normal temperature, it cut out to 15 mm width, and peeling strength was measured with the tensile tester. The peeling strength of 1 N / 15 mm or less evaluated as being excellent in heat resistance.

(5) appearance unevenness

In the same manner as in (3), a laminated film was obtained. Using the obtained film, the inside dimension was umbilicalized so that it might become 100 mm x 150 mm (heat seal width 10 mm), and 200 ml of water was sealed. After the umbilical cord product which enclosed water was retort-processed at 121 degreeC for 30 minutes, the state of appearance nonuniformity was visually evaluated.

TABLE 1

TABLE 2

As is evident from the table, the sealant films of the present inventions of Examples 1 to 8 had easy tearing strength and good straight cut property. Moreover, the peeling strength in internal surface fusion evaluation of the sealant films of Examples 1-6 and 8 was 1 N / 15 mm or less. In addition, in the sealant films of Examples 1 to 6, the appearance unevenness was not visually recognized. On the other hand, the sealant film of the comparative example was not obtained tear property and favorable straight cut property, and did not have favorable tear property.

Claims (15)

The outer layer (A), the intermediate layer (B) and the inner layer (C) is made of a laminated film laminated,
Outer layer (A) and inner layer (C) contain polyethylene resin,
Intermediate layer (B) contains linear low density polyethylene (b1) and cyclic olefin resin (b2), and content of the said cyclic olefin resin (b2) in the resin component contained in the said intermediate layer (B) is 20-40. Mass%,
The normalized molecular orientation MORc value when the reference thickness measured by a microwave system molecular orientation system is 60 micrometers is 1.025 or more, The sealant film characterized by the above-mentioned. The method of claim 1,
The sealant film whose thickness of the said intermediate | middle layer (B) is 10-50% of the total thickness of a laminated | multilayer film. The method according to claim 1 or 2,
The sealant film whose average density of the resin component in the said outer layer (A) and inner layer (C) is 0.940 g / cm <3> or more, and the density of the said linear low density polyethylene (b1) is 0.937 g / cm <3> or more. The method according to any one of claims 1 to 3,
The sealant film whose content of the said linear low density polyethylene (b1) in the resin component contained in the said intermediate | middle layer (B) is 60-80 mass%. The method according to any one of claims 1 to 4,
The sealant film whose glass transition temperature of the said cyclic olefin resin (b2) is 140 degrees C or less. The method according to any one of claims 1 to 5,
A sealant film having a total thickness of 20 to 150 µm. The method according to any one of claims 1 to 6,
The sealant film whose MFR of said linear low density polyethylene (b1) is 0.1-20 g / 10min, and MFR of the said cyclic olefin resin (b2) is 0.2-17 g / 10min. The packaging material using the sealant film in any one of Claims 1-7. As a method of manufacturing the sealant film which consists of laminated | multilayer film which laminated | stacked the outer layer (A), the intermediate | middle layer (B), and the inner layer (C) by the coextrusion inflation method,
The resin for the outer layer forming the outer layer (A) and the resin for the inner layer forming the inner layer (C) contain a polyethylene resin, and the resin for the middle layer forming the intermediate layer (B) is a linear low density polyethylene (b1). And cyclic olefin resin (b2) is contained, Content of the said cyclic olefin resin (b2) in the resin component contained in the said resin for intermediate | middle layers is 20-40 mass%,
A blow ratio of 1.0 to 2.3 and coextrusion inflation molding at a drawdown ratio of 20 to 60 are used. The method of claim 9,
The manufacturing method of the sealant film whose MORc value of the said laminated | multilayer film is 1.025 or more. The method of claim 9 or 10,
The thickness of the intermediate | middle layer (B) of the said laminated | multilayer film is a manufacturing method of the sealant film whose 10-50% of the total thickness of a laminated | multilayer film. The method according to any one of claims 9 to 11,
The manufacturing method of the sealant film whose average density of the resin component in the said outer layer (A) and inner layer (C) is 0.940 g / cm <3> or more, and the density of the said linear low density polyethylene (b1) is 0.937 g / cm <3> or more. The method according to any one of claims 9 to 12,
The glass transition temperature of the said cyclic olefin resin (b2) is 140 degreeC or less, The manufacturing method of the sealant film. The method according to any one of claims 9 to 13,
The manufacturing method of the sealant film whose total thickness is 20-150 micrometers. The method according to any one of claims 9 to 14,
The MFR of said linear low density polyethylene (b1) is 0.1-20g / 10min, and the MFR of said cyclic olefin resin (b2) is 0.2-17g / 10min.