JP4968769B2 - Laminated film and multiple packaging bag comprising the same - Google Patents

Description

  The present invention relates to a packaging bag for filling and packaging the content of a liquid or viscous fluid containing oils and fats such as foods and pharmaceuticals, etc., and mainly used for business use. It is used for automatically filling and packaging liquid foods containing fats and oils, and heat-treating at relatively high temperatures for purposes such as sterilization. The present invention relates to a flexible laminated film excellent in mechanical characteristics such as pinhole property and drop impact resistance, or a multiple packaging bag made of the same.

  Conventionally, liquid or viscous foods used for business have been packed in hard containers such as metals and plastics for transportation, storage and sales. However, a hard container such as metal has drawbacks such as a bulky container after use, difficulty in taking out the contents, and difficulty in reusing the container. Recently, flexible plastic packaging bags are often filled from the standpoints of ease of handling, weight reduction, and reduction of waste. These flexible packaging materials have barrier properties against oxygen gas, water vapor, etc., flexibility, impact resistance, pinhole resistance, puncture resistance, transparency, heat resistance, heat sealability, quality retention, printability, opening Various properties are required, such as properties and suitability for filling and packaging. In particular, when the contents are fluid, viscous fluid, or for low-temperature storage, the pinhole resistance of the packaging bag is a fundamental problem with respect to content protection and leakage. There have been proposals for packaging materials with various film materials and configurations.

  Although a single layer film is often used as a packaging bag material, it is necessary to use a laminated film having functions such as film strength, heat sealing property, gas barrier property, etc., because it is necessary to satisfy the above required characteristics. preferable. The laminate film is composed mainly of a biaxially stretched polyester film with high strength and a biaxially stretched nylon film with excellent impact properties such as low-temperature fatigue and impact as the base film for maintaining the mechanical strength. Or as a sealant film that can be used in combination and can be heat-sealed, it is generally a polyethylene film, and in particular, linear low with excellent properties such as heat seal strength, stress crack resistance, impact resistance, and low-temperature characteristics. A density polyethylene film is preferably used.

  Now, as a solution to the generation of pinholes due to repeated bending and bending of packaging bags due to vibration during the transportation process, there is a structure with a partially unbonded part between the base film layer and the sealant layer. Proposed pinhole-resistant packaging materials have been proposed. That is, a polyolefin-based resin film that can be a sealant layer and a gas barrier layer having gas barrier properties were mixed and dispersed at an arbitrary ratio between the two layers, a material having adhesive properties, and a material having no adhesive properties. A packaging material is disclosed in which a material laminated with an adhesive layer and having adhesive properties occupies 50% or more of the surface of an adherend (see Patent Document 1).

  In addition, as another solution, a multi-layer bag in which laminate films are doubled or stacked is used, and an outer bag is interposed between an innermost bag for directly packaging liquid and an outer container (corrugated cardboard), so that it can be transported. Technology that improves pinhole resistance and drop bag resistance by preventing the innermost bag and corrugated cardboard from rubbing directly due to vibration, etc., and preventing an increase in bending stress applied to the laminate film when the bag is bent is disclosed. ing. Specifically, at least one film selected from the group consisting of a biaxially stretched nylon film and a biaxially stretched polyester film, and a linear low density polyethylene film are composed of two or more layers of films bonded to each other by blocking. Is a packaging material characterized by Even if a pinhole occurs in one film, this multiple bag is intact, and the other sheet is not damaged. Also, with respect to bending stress, one individual independent film receives the stress, and the other sheet Since it can slip and escape, there is no fear of applying an extreme bending stress, and it has excellent mechanical strength (see Patent Document 2).

Recently, from the viewpoint of hygiene requirements for food and the efficiency of this response, heat-sterilized liquid foods are filled and packaged at a high temperature, or heat-treated at a relatively high temperature for the purpose of heat sterilization in a packed and packaged state. There is a need to be able to do it. The technology described in Patent Document 2 is the density of linear low-density polyethylene used to obtain two or more layers of films that are mutually blocking-adhered to the extent that they do not impair machine suitability during laminating processes, bag making, and packaging operations. Therefore, by high-temperature treatment such as heat sterilization, a strong heat blocking is formed between the innermost layer and the outer layer, and the behavior as a single layer is exhibited, which is a characteristic of the multiple bag. It has been found that bending fatigue resistance, pinhole resistance, and drop impact resistance are remarkably lowered, which is a serious problem.
JP 2004-148635 A Japanese Patent No. 3515194

  The problem of the present invention is that when a laminated film is used to make a fluid packaging containing oils and fats, the packaging has excellent performance in bending fatigue resistance, pinhole resistance, drop impact resistance, etc. Provided are laminated films and the like.

  The first of the present invention is a laminated film in which a base material layer (1), a first bonding layer (2), an intermediate layer (3), a second bonding layer (4), and a sealant layer (5) are sequentially laminated. The intermediate layer (3) is a polyolefin resin film, the sealant layer (5) is a linear low density polyethylene resin film, and the second bonding layer (4) is formed by an extrusion lamination method. It is the laminated film for packaging of the fluid containing the fats and oils which is the made polyethylene-type resin layer of thickness 3-13 micrometers. Here, the base material layer (1) is at least one film selected from the group consisting of a biaxially stretched nylon film and a biaxially stretched polyester film, and the base material layer (1) and the intermediate layer ( It is preferable that a gas barrier layer (7) is further laminated between the layer 3).

  A second aspect of the invention is a multiple packaging bag for fluid packaging containing fats and oils, which is produced by heat sealing with the above-mentioned laminated film and with the sealant layer (5) on the inside.

  A third aspect of the invention is the differential scanning calorific value of the linear low density polyethylene resin in which the fluid containing oils and fats is filled and sealed in the multiple packaging bag, and the sealant layer (5) is formed at 70 ° C. or higher. It is a packaging method for a fluid containing fats and oils, which is heat-treated at a temperature not higher than 5 ° C. lower than the crystal melting peak temperature Tpm measured by a meter.

  A fourth aspect of the invention is that the above-described multiple packaging bag is hermetically filled with a liquid / viscous food containing fats and oils, and peeling between the intermediate layer (3) and the sealant layer (5) of the laminated film. It is a multiple package body whose strength is in the range of 5 to 100 g / 15 mm.

  When using a laminated film to make a fluid package containing oils and fats, there is no problem with the fluid's sealing properties, etc., and the package's bending fatigue resistance, pinhole resistance, drop impact resistance, etc. Excellent resistance in performance.

  Hereinafter, embodiments of the laminated film of the present invention and a multi-packaging bag comprising the same will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of a laminated structure of a laminated film according to the present invention. In FIG. 1, the base material layer (1) is bonded to the intermediate layer (3) made of a polyolefin resin via the first bonding layer (2). The intermediate layer (3) is bonded to the sealant layer (5) via a second bonding layer (4) formed by extrusion lamination of a polyethylene resin having a thickness of 3 to 13 μm. FIG. 2 shows another embodiment relating to the laminated film. In addition to the laminated structure of the above structure, a gas barrier layer (between the first bonding layer (2) and the base material layer (1) is shown. 7) is laminated and laminated through the third bonding layer (2a). As described above, the laminated film can be variously modified as necessary with respect to the base material layer (1) and the first bonding layer (2).

  By the way, in general, in the extrusion lamination using a polyethylene-based resin, those who are familiar with the work are familiar, but in order to develop a sufficient laminate strength, the thickness of the extruded polyethylene-based resin is 15 μm or more. Things have been done. However, unlike the conventional concept, the present invention is characterized in that the second bonding layer (4) having a thickness of 3 to 13 μm, which is as thin as possible in production, is provided.

  As a result of earnest research, the inventor provided an intermediate layer (3) in addition to the base material layer (1), and a second bonding layer (4) between the intermediate layer (3) and the sealant layer (5). In the state where the above-mentioned thin film is in contact with the contents of the liquid / viscous food containing the fats and oils, the laminated film is further heat-treated. The laminate strength between the second bonding layer (4) and the sealant layer (5), or between the intermediate layer (3) and the second bonding layer (4) is reduced, and an easily peelable interface is formed to form a packaging material. Has been found to improve the resistance to pinholes and impact fracture. That is, when the package is subjected to bending or a drop impact due to vibration, local stress generated in the packaging material induces delamination of the laminated film constituting the packaging bag, and is dispersed or relaxed. The present inventors have found that the destruction of the packaging material can be prevented in advance.

  Here, the appropriate heat treatment is 70 ° C. or higher and 5 ° C. from the crystal melting peak temperature Tpm measured by a differential scanning calorimeter (DSC) of the linear low density polyethylene resin forming the sealant layer (5). Heat treatment to a temperature below a low temperature. That is, a bag is made from the laminated film, and the temperature of the contents filled in the bag is at least 70 ° C. or higher because it is heated for sterilization if it is a liquid food. 5), the second bonding layer (4), and the intermediate layer (3) do not cause strong melt adhesion, and the crystal melting of the sealant layer (5) is the upper limit temperature at which an easily peelable interface can be expressed. Heat treatment is performed in a temperature range of Tpm-5 ° C. By doing so, there is no problem with the sealed packaging of the contents, and the local stress generated in the packaging material when the packaging body is subjected to bending or dropping impact due to vibration constitutes the packaging bag. Induces delamination of laminated films.

  FIG. 3 shows a pillow packaging bag 9 which is an example of a double packaging bag manufactured from the laminated film of the present invention (the heat seal portion is indicated by hatching). The pillow packaging bag 9 is heat-sealed with a horizontal seal portion 8a and a back-attached vertical seal portion 8b with the sealant layer inside. The shape of the packaging bag is not limited to the pillow packaging bag, and may be various known shapes used for packaging fluids containing fats and oils.

  FIG. 4 is an enlarged cross-sectional view of the seal portion when the contents 11 which is a fluid containing oils and fats are filled and packaged in a multiplex bag obtained by folding the laminated film having the structure of FIG. 10 in the figure was sealed by heat-sealing by means of heat sealing, impulse sealing, ultrasonic sealing, high-frequency sealing, etc. with the linear low density polyethylene films of the sealant layer (5) overlapped inside each other. It is a seal part 10. In the seal portion 10, a linear low density polyethylene sealant layer (5), a polyethylene resin second bonding layer (4) formed by an extrusion laminating method, and a polyolefin resin intermediate layer (3) are melted. A total of six layers are firmly bonded and integrated by pressure bonding. That is, in the seal portion 10, all the laminated laminate layers constituting the packaging material can be firmly bonded and integrated to prevent leakage of the content liquid.

  Except for the seal portion 10, the contents 11 are in direct contact with the sealant layer (5), and the sealant layer (5) is laminated on the intermediate layer (3) via the second bonding layer (4). The base material layer (1) is laminated on the layer (3) via the first bonding layer (2). In the case where the content is a fluid containing fats and oils, specifically a liquid or mucus containing fats and oils such as fluid food or pharmaceuticals, the temperature range as described above for sterilization. By performing the heat treatment, the peel strength between the intermediate layer (3) and the sealant layer (5) of the laminated film is reduced to 5 to 100 g / 15 mm. In addition, when the content is water that does not contain fats and oils, the peel strength does not decrease and remains high.

  The cause of such a phenomenon is not clear, but the fluid containing the fats and oils that are the contents of the packaging bag comes into contact with the laminated film of the packaging bag at a high temperature, so that the fats and oils contained in the contents It is thought that the kind penetrates into the linear low density polyethylene of the sealant layer, reduces the adhesion between the layer and the bonding layer, and forms an easily peelable interface there. If the package obtained in this way is packed in cardboard, etc., used for transportation and transportation, and subjected to vibration or drop impact, even if it receives instantaneous local stress due to bending or impact, the intermediate layer It is presumed that pinhole resistance and drop bag resistance are improved by the occurrence of a peeling phenomenon between the sealant layer and the instantaneous stress distribution. The peel strength between the intermediate layer (3) and the sealant layer (5) is more preferably in the range of 5 to 70 g / 15 mm.

  Hereinafter, the structure of the laminated film consisting of at least five layers will be described. First, the main purpose of the base material layer (1) is to impart toughness to the laminated film. When the base material layer (1) has a plurality of performances required for the packaging bag, for example, when both toughness and gas barrier properties are required, a composite base material in which layers having performances corresponding thereto are laminated. It can be a layer. The thickness of the base material layer (1) can be appropriately selected according to the purpose of the packaging bag, but is preferably 10 to 50 μm from the viewpoint of mechanical strength such as piercing and abrasion resistance.

  The base material constituting the base material layer (1) may be a stretched film or sheet of polyamide resin, polyester resin, or polypropylene resin. The base material layer (1) appropriately has necessary properties such as film strength, toughness, gas barrier properties against oxygen gas, water vapor, etc., impact resistance, flex pinhole resistance, puncture resistance, and the like. Typical examples of the stretched film include a biaxially stretched nylon (trademark) film, a biaxially stretched polyester film, and a biaxially stretched polypropylene film.

  Examples of the biaxially stretched nylon film include MXD nylon 6 film, MXD nylon resin and nylon 46, nylon 6, nylon 66, nylon 612, nylon 11, nylon 12, and various polyamide-based resins indicated by trade names. Examples thereof include simultaneous or sequential biaxially stretched films that are single or co-extruded by a T-die method or an inflation method. In particular, nylon 6 film is most preferable from the viewpoint of cost and ease of film formation. Examples of the biaxially stretched polyester film include, for example, polyethylene terephthalate, polybutylene terephthalate, etc., or a biaxially stretched film by a T-die method of a copolymer. Among these, polyethylene terephthalate alone or A copolymer is most preferable from the viewpoint of cost.

  By the way, when the contents react with oxygen, discoloration, browning, changes in taste and fragrance, decrease in nutritional components, generation of harmful components, etc., or in the presence of oxygen, bacteria, mold, When microorganisms such as yeast are likely to grow, in order to prevent this, a base layer such as the above-described biaxially stretched nylon film, biaxially stretched polyester film, biaxially stretched polypropylene film, and an intermediate layer (3 described later) ) Is preferably provided with a gas barrier layer (7) to block oxygen. As the gas barrier layer, polyvinylidene chloride resin film, ethylene-vinyl alcohol resin film, polyvinyl alcohol resin film, polyvinylidene chloride coating thin film, crosslinked polyacrylic acid coating thin film, metal vapor deposition thin film such as aluminum, A metal oxide vapor-deposited thin film such as silicon oxide or aluminum oxide, or one or more of aluminum foil can be laminated.

  Next, the first bonding layer (2) is a layer for bonding the base material layer (1), the intermediate layer (3), and the gas barrier layer (7) provided as necessary, As a lamination method for forming one bonding layer (2), for example, a dry lamination method, a solvent-free lamination method, a hot melt lamination method, an extrusion lamination method, or the like, which are bonded via an adhesive, may be used.

  In the case of the dry lamination method, the type of adhesive is selected in consideration of the type of contents, the packaging form, etc., but it is preferable to use a one-component or two-component polyurethane adhesive. More preferably, it is a two-component polyester polyurethane adhesive.

  Corona discharge treatment, ozone treatment, anchor coating agent on the bonding surface of one or both of the layers to be laminated prior to or at the same time as the lamination to improve the adhesion between the films to be laminated It is preferable to perform surface treatment by a method such as coating.

  The intermediate layer (3) complements the base material layer (1) by firmly adhering to the base material layer (1), and after being a packaging bag filled with the contents, excluding the heat seal portion, It is an essential component for expressing the function as a multiple bag that forms a movable interface with the sealant layer (5) and disperses the stress when subjected to bending or instantaneous impact stress. The intermediate layer is preferably made of a polyolefin polymer. Specifically, linear low density polyethylene, high pressure method low density polyethylene, low pressure method high density polyethylene, polypropylene, ethylene-propylene block copolymer, ethylene-propylene random copolymer, or a mixture thereof may be used. preferable. Among these, linear low density polyethylene is particularly preferable from the viewpoint of heat seal strength. Additives such as a lubricant may be blended in the resin forming these intermediate layers (3). The thickness of the intermediate layer is preferably 20 to 80 μm, more preferably 25 to 60 μm, from the viewpoint of automatic filling characteristics.

  Next, the second bonding layer (4) has a function of bonding the intermediate layer (3) and the sealant layer (5) at the time of bag making and is partly subjected to bending or instantaneous impact stress. It is a layer for enabling the intermediate layer (3) and the sealant layer (5) to move relative to each other by being peeled off.

The material of the second bonding layer (4) is preferably an ethylene polymer, and specifically, linear low density polyethylene, high pressure method low density polyethylene, and high density polyethylene are preferred. Of these, linear low density polyethylene is more preferable. Particularly for the purpose of hot pack, linear low density polyethylene is preferred. The density of the linear low density polyethylene is preferably 0.905 to 0.930 g / cm ³ , more preferably 0.915 to 0.925 g / cm ³ . The melt index (190 ° C., 2.16 kg) is preferably 2 to 12 g / 10 minutes, more preferably 5 to 10 g / 10 minutes.

  You may mix | blend another resin with a 2nd joining layer (4). Examples of other resins include ethylene-unsaturated carboxylic acid copolymers. The unsaturated carboxylic acid is not particularly limited as long as it is an unsaturated carboxylic acid copolymerizable with ethylene. Specific examples of the ethylene-unsaturated carboxylic acid copolymer include ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-ethacrylic acid copolymer, ethylene-maleic acid copolymer, ethylene-fumaric acid. Examples thereof include a copolymer and an ethylene-maleic anhydride copolymer.

  Of these, ethylene-acrylic acid copolymers and ethylene-methacrylic acid copolymers are preferred. Moreover, you may use the other monomer copolymerizable with ethylene and unsaturated carboxylic acid. Examples of such other monomers include unsaturated carboxylic acid esters such as methyl acrylate, isobutyl acrylate, diethyl maleate, and the like. The amount is 40% by weight or less, preferably 30% by weight or less, based on the resin amount of the bonding layer (4).

  The ethylene-unsaturated carboxylic acid copolymer referred to here includes, for example, a maleic anhydride graft obtained by grafting maleic anhydride onto polyethylene in addition to a copolymer of ethylene and unsaturated carboxylic acid. Also included are graft copolymers, such as polyethylene copolymers.

  Further, as other resins that may be blended, in addition to the above-mentioned ethylene-unsaturated carboxylic acid copolymer, ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer Mention may be made of ethylene-unsaturated carboxylic acid ester copolymers such as polymers. In addition, it is preferable not to use additives, such as a lubricant, for the polyethylene-type resin used for a 2nd joining layer (4).

  As a method for forming the second bonding layer (4), an extrusion lamination method is used. Prior to laminating, the surface to be bonded and bonded to either or both of the intermediate layer (3) and the sealant layer (5) to be laminated is subjected to surface treatment by a method such as corona discharge treatment, ozone treatment or anchor coating agent application. It is preferable. The thickness of the layer is from 3 to 13 μm, preferably from 5 to 12 μm, more preferably from 8 to 8 in order to develop extrusion lamination processing characteristics, interfacial adhesiveness, and interfacial peelability by heat treatment, which is a feature of the present invention. 10 μm.

Next, the sealant layer (5) is a layer having a heat sealing function necessary for bag making. The resin used here is preferably linear low density polyethylene. The density of the linear low density polyethylene is preferably 0.905 to 0.925 g / cm ³ . The melt index (190 ° C., 2.16 kg) is preferably 1 to 10 g / 10 minutes. The thickness of the layer of the sealant layer (5) is preferably 30 to 100 μm.

  A laminated film in which at least five layers are laminated is used to make a packaging bag, and when a fluid containing oils and fats is hermetically packaged and subjected to appropriate heat treatment, the sealing performance is Despite no problem, the peel strength of the laminated film other than the seal portion is reduced to the above-mentioned fixed range, and therefore, the local stress that the package receives during transportation induces delamination of the laminated film, It becomes possible to prevent the package from being destroyed by causing stress dispersion and stress relaxation.

  The appropriate heat treatment to be applied to the package has already been described above, but the measurement with a differential scanning calorimeter (DSC) used in the temperature range of the heat treatment may be performed according to JIS K7121. Specifically, the test piece is put into a container of a DSC apparatus, heated and melted to a temperature about 30 ° C. higher than the end of the melting peak at a temperature rising rate of 10 ° C./min, held at that temperature for 10 minutes, and then 10 ° C. A test piece cooled to room temperature at / min is subjected to the measurement. The above-described crystal melting peak temperature Tpm is the lowest temperature peak temperature Tpm in the case of a resin having two or more melting peaks.

  When the peel strength between the intermediate layer (3) and the sealant layer (5) of the laminated film is measured after the heat treatment at a temperature of 70 ° C. or higher and 5 ° C. or lower than the crystal melting peak temperature Tpm. Then, after making a laminated film into a bag, filling a liquid food containing fats and oils, and heat-sealing to make a package, the package is heated to the above temperature range for at least 10 minutes and then cooled to room temperature. For measurement. The peel strength may be measured according to JIS Z0237, and the test piece is peeled off at a speed of 50 mm per minute by a 180-degree peeling method.

  The above-mentioned temperature range of the appropriate heat treatment corresponds to the temperature when the contents filled in the multi-packaging bag made of the laminated film, that is, the fluid containing the oil and fat is heated for the purpose of sterilization or the like. For this reason, by performing a heat sterilization treatment after filling the contents, the laminated film becomes a multi-film consisting essentially of two or more films. In order to make the laminated film function substantially triple, in FIG. 1, a second intermediate layer 3 and a second bonding layer 4 are further provided between the bonding layer 4 and the sealant layer 5. For a total of 7 layers.

  The resin forming the sealant layer (5) preferably contains a lubricant. In addition, it is effective to generate a carbonyl group in advance on the surface on the side of the sealant layer (5) to be laminated by corona discharge treatment or the like. The surface tension obtained by the corona discharge treatment is desirably 38 to 50 dyn / cm.

Examples of the lubricant that can be blended in the resin of the intermediate layer (3) and the sealant layer (5) are shown below. For reference, a representative trade name of each lubricant and a manufacturer name or the contents of the lubricant are illustrated together.
(I) Oleic acid amide lubricant: Armoslip CP (Lion Akzo), Neutron (Nippon Seika), Neutron E-18 (Nippon Seika), Amide O (Nitto Chemical), Alfro E-10 (Japan) (Oil), Diamond O-200 (Nippon Kasei), Diamond G-200 (Nippon Kasei), etc. (b) Erucic acid amide lubricants; Alfro-P-10 (Nippon Fats and oils), etc. Alfro-S-10 (Nippon Yushi), Neutron 2 (Nippon Seika), Diamond 200 bis (Nippon Kasei) etc. (d) Bis fatty acid amide lubricants; Bisamide (Nippon Kasei), Diamond 200 bis (Japan) Kasei), Armo wax EBS (Lion Akzo) etc. (e) Alkylamine lubricants; Electro stripper TS-2 (Kao soap) etc. (f) Hydrocarbons Agents: liquid paraffin, natural paraffin, micro wax, synthetic paraffin, polyethylene wax, polypropylene wax, chlorinated hydrocarbon, fluorocarbon, etc. (g) Fatty acid type lubricants; higher fatty acids (preferably C12 or more), oxy fatty acids, etc. Ester lubricants: lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, polyglycol esters of fatty acids, fatty alcohol esters of fatty acids, etc. (Li) alcohol lubricants; (nu) metals such as polyhydric alcohols, polyglycols, polyglycerols Soap: Compounds of higher fatty acids such as lauric acid, stearic acid, ricinoleic acid, naphthenic acid, oleic acid and metals such as Li, Mg, Ca, Sr, Ba, Zn, Cd, Al, Sn, Pb, etc. Silicone lubricants; various grades of dimethyl Polysiloxane and modified products thereof (manufactured by Shin-Etsu Silicone, Toray Silicone), etc.

  The blending amount of the lubricant in the resin forming the intermediate layer (3) and the sealant layer (5) is preferably 50 to 1000 ppm, more preferably 100 to 600 ppm, and further preferably 150 to 400 ppm.

  Next, the manufacturing method of the laminated film which consists of each of these layers is described. As a lamination method for joining the base material layer (1) and the intermediate layer (3) formed in advance, for example, a dry lamination method, an extrusion lamination method, etc., which are bonded via an adhesive, can be used. The dry lamination method is preferred from the performance of the packaging material to be produced. By using these lamination methods, the first bonding layer (2) is formed between the base material layer (1) and the intermediate layer (3).

  Next, the raw film of the laminated film composed of the base material layer (1), the first bonding layer (2), and the intermediate layer (3) is crushed, and the raw film of the sealant layer (5) is crushed from one side, Paste both original films. At that time, a polyethylene resin melt forming the second bonding layer (4) is extruded into a film form from an extruder equipped with a T-die on the bonding surfaces of both films, and these are laminated. Is sandwiched between nip rolls and the like, and the two raw films are bonded together by pressing. Thus, a laminated film in which the base material layer (1), the first bonding layer (2), the intermediate layer (3), the second bonding layer (4), and the sealant layer (5) are sequentially laminated is obtained.

  The laminated film consisting of at least 5 layers thus obtained is heat-treated in a state where the sealant layer is in contact with a fluid containing oils and fats, for example, a liquid / viscous food or medicine (for example, 85 ° C. × 30 minutes), the peel strength between the sealant layer and the intermediate layer decreases, and the range is 5 to 100 g / 15 mm. More preferably, it is the range of 5-70 g / 15mm.

  Examples of foods containing fats and oils include liquid and fluid foods such as liquid soup, sauce, sauce, soy sauce, ketchup, curry, miso, stew, jam, mayonnaise, dressing, sweet potato, fish meat paste, etc. However, the present invention is not limited thereto, and filling and packaging of liquid and fluid substances other than these foods is also possible.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the following specific aspects.

A laminated film having the layer structure shown in FIG. 1 was prepared. A biaxially stretched nylon film having a thickness of 15 μm is used as the base layer (1), and a linear low density polyethylene resin having a thickness of 25 μm (density: 0.925 g / cm ³ , MI: 7 g / 10) as the intermediate layer (3). 3) Polyester adhesive of 3 g / m ² as a first bonding layer (2) is applied to one surface of the base material layer (1) using an unstretched film formed from (1), and an intermediate layer is applied to the coated surface. By laminating (3), lamination was performed by a dry lamination method.

Next, an unstretched film formed from a linear low density polyethylene resin (density: 0.920 g / cm ³ , MI: 7 g / 10 min) having a thickness of 50 μm was prepared as a sealant layer (5), and a corona was formed on one side thereof. The corona-treated surface and the surface on the intermediate layer (3) side of the laminated film described above are opposed to each other, and a linear low-density polyethylene resin having a thickness of 12 μm or 9 μm (density: 0.00). A melt-extruded resin layer using 920 g / cm ³ , MI: 7 g / 10 min, Tpm: 105 ° C.) was laminated as the second bonding layer (4) to obtain two kinds of laminated films . As a result, as a layer structure, a base layer (1) made of biaxially stretched nylon / a first bonding layer made of polyurethane adhesive (2) / an intermediate layer made of a linear low density polyethylene unstretched film (3) / melt extruded 2 having a total thickness of 105 μm (Table 1 a) and 102 μm (Table 1 b), comprising a second bonding layer (4) made of polyethylene resin / a sealant layer (5) made of a linear low density polyethylene unstretched film. A seeded laminated film was obtained. The mechanical strength of the obtained laminated film and the strength of the seal part are shown in Table 1 as heat seal strength.

In addition, the kind of material used above is shown below.
-Biaxially stretched nylon film: Product name “NH # 15” (manufactured by Unitika Ltd.)
・ Unstretched linear low-density polyethylene film: Trade name “XHT” (manufactured by Futamura Chemical Co., Ltd.)
Melt extruded polyethylene resin: Trade name “021GT” (manufactured by Ube Industries)
・ Unstretched linear low-density polyethylene film: Trade name “MTN” (manufactured by Nimura Chemical Co., Ltd.)

  The obtained two kinds of laminated films were each slitted to a width of 420 mm, and a packaging bag similar to that shown in FIG. 3 was prepared using a vertical pillow automatic filling bag making machine. Specifically, after forming the vertical seal portion 8b of FIG. 3 and then forming the lower horizontal seal portion 8a, 1 kg of hot water at 90 ° C. containing 0.5 or 4% by weight of edible oil is supplied from the nozzle. In a heated state (hot pack), provided with an upper horizontal seal portion 8c, and a package (sample: 260 mm in length, 200 mm in width) filled with the contents shown in FIG. 1-4) were obtained. Next, each package was held at 90 ° C. for 30 minutes for boil treatment (heat treatment). The sealing strength of the heat-sealed portion of the package before and after the boil treatment, and the laminate strength of the laminated film portion in contact with the filled contents were measured as the peel strength between the intermediate layer (3) and the sealant layer, and the result was n The average value of Equation 8 is shown in Table 2.

  As is clear from Table 2, the seal strength of the heat seal part maintains a large value without being changed by the heat treatment. On the other hand, in the part of the laminated film that is not heat-sealed, it can be seen that the peel strength after the heat treatment at 90 ° C. for 30 minutes is significantly lower than the strength after the hot pack. That is, it can be seen that the peel strength between the intermediate layer (3) and the sealant layer (5) is reduced by the heat treatment, and an easily peelable interface is formed.

Comparative Example 1

  As the contents to be filled in the packaging bag, except that hot water of 90 ° C. not containing edible oil was used, a package was obtained in the same manner as in Example 1, and the peel strength of each part was determined in the same manner as in Example 1. It was measured. The results are shown in Table 2 as an average value of n number 8. When the content is only hot water, it can be seen that the laminate strength (peel strength) after hot pack is greatly increased with respect to the value before hot pack.

A laminated film was prepared in the same manner as in Example 1 except that the thickness of the second bonding layer (4) made of the melt-extruded resin was 10 μm and the thickness of the sealant layer (5) was 80 μm. Axis-stretched nylon substrate layer (1) / polyurethane adhesive first bonding layer (2) / linear low density polyethylene unstretched film intermediate layer (3) / melt-extruded polyethylene resin second bonding layer (4) A laminated film having a total thickness of 133 μm, comprising a sealant layer (5) of a linear low density polyethylene unstretched film was obtained. The laminated film was slit to a width of 420 mm, and a pillow package filled with 1 kg of 90 ° C. hot water to which edible oil was added to 4 wt% was obtained in the same manner as in Example 1. The filled pillow bag was subjected to a drop test and a shake test by the following method, and the number of drops until the bag was broken and the shaking time (min) until the pinhole was generated were measured. The results are shown in Table 3. From Table 3, it was found that a multilayer bag made of a laminated film is excellent in impact resistance, flex fatigue resistance, and pinhole resistance.
(Drop test)
Test method: The pillow package was subjected to horizontal and vertical alternating drop tests in accordance with JIS Z0238 in the order of the top, bottom, bottom and top in accordance with the name of the heavy packaging bag of JIS Z0201.
・ Falling distance: 80cm
Measurement temperature: 5 ° C. (tested in a large refrigerator)
-Judgment: The presence or absence of a broken bag after dropping and the presence or absence of a pinhole were examined, and the number of drops that resulted in the broken bag or the occurrence of a pinhole was recorded.
(Shaking test)
・ Testing method: Two pillow packaging bodies are placed on a cardboard box with inner dimensions of 410 x 210 x 170 mm, placed on a bottom plate, separated by a partition plate (made of cardboard), and tested in an unsealed state. Provided.
-Shaking test machine: The shaking table used the thing which moved horizontally so that the swing width might be set to 30 mm, and tested on the conditions of 300 reciprocations per minute.
Measurement temperature: 5 ° C (tested in a large refrigerator)
-Judgment: After a shaking test for a predetermined time, the presence or absence of a broken bag and the presence or absence of a pinhole were examined, and the time until the occurrence of broken bag or pinhole was recorded.

Comparative Example 2

A biaxially stretched nylon film having a thickness of 15 μm is used as the base material layer (1), a polyester polyurethane adhesive is applied to the back surface thereof at 3 g / m ² as the first bonding layer (2), and the sealant layer (5). As a film, a non-stretched film formed from a linear low density polyethylene resin having a thickness of 120 μm (density: 0.925 g / cm ³ , MI: 7 g / 10 min) was laminated by a dry lamination method to form a three-layer film. . As a layer structure, there are no intermediate layer (3) and second bonding layer (4), biaxially stretched nylon base material layer (1) / first bonding layer of polyurethane adhesive (2) / linear A three-layer film having a total thickness of 138 μm consisting of a sealant layer (5) of a low-density polyethylene unstretched film was obtained. The film was slit to a width of 420 mm, and a pillow package filled with 1 kg of 90 ° C. hot water to which edible oil was added to 4 wt% was obtained in the same manner as in Example 1. The same test evaluation as in Example 2 was performed using the pillow package. The results are shown in Table 3. Although it is a laminated film having almost the same thickness as that of Example 2, it can be seen that, in the laminated film that is firmly integrated, breakage due to drop impact and bending fatigue due to vibration occurs at the initial stage of the test. .

It is a schematic diagram which shows the cross-sectional structure example of a laminated film. It is a schematic diagram which shows the other cross-sectional structure example of a laminated | multilayer film. It is a front view which shows an example of the pillow-shaped multiple packaging bag. It is the schematic diagram which expanded a part of seal part cross section of the example of a multiple packaging bag.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material layer 2 Joining layer 2a Joining layer 3 Intermediate layer 4 Joining layer 5 Sealant layer 7 Gas barrier layer 8a-c Heat seal part 9 Pillow packaging bag 10 Seal part 11 Contents

Claims (7)

A laminated film in which a base material layer (1), a first bonding layer (2), an intermediate layer (3), a second bonding layer (4), and a sealant layer (5) are sequentially laminated, the intermediate layer (3) is a polyolefin resin film, the sealant layer (5) is a linear low density polyethylene resin film, and the second bonding layer (4) is a linear low density polyethylene formed by an extrusion lamination method. A fluid-laminated laminated film containing oils and fats, which is a resin layer having a thickness of 3 to 13 μm, which is a high-pressure low-density polyethylene or high-density polyethylene .   The base material layer (1) is at least one film selected from the group consisting of a biaxially stretched nylon film and a biaxially stretched polyester film, and the base material layer (1), the intermediate layer (3), The laminated film according to claim 1, further comprising a gas barrier layer (7) laminated therebetween.   A multi-packaging bag for fluid packaging containing fats and oils, which is produced by heat sealing using the laminated film according to claim 1 or 2 with the sealant layer (5) inside.   Filling and sealing the fluid containing fats and oils in the multiple packaging bag according to claim 3, and using a differential scanning calorimeter of linear low density polyethylene resin at 70 ° C or higher and forming the sealant layer (5). A packaging method for a fluid containing fats and oils, which is heat-treated at a temperature not higher than 5 ° C. lower than the measured crystal melting peak temperature Tpm. A multi-packaging body in which a fluid containing oils and fats is packaged in a bag made by heat sealing with the sealant layer (5) on the inside using the laminated film according to claim 1 or 2. The multiple package according to claim 5 is 70 ° C or higher and 5 ° C lower than a crystal melting peak temperature Tpm measured by a differential scanning calorimeter of a linear low density polyethylene resin forming the sealant layer (5). A multiple package obtained by heat treatment at a temperature below the temperature. The wrapping bag according to claim 3 is hermetically filled with a liquid / viscous food containing fats and oils, and has a peel strength between the intermediate layer (3) and the sealant layer (5) of the laminated film. Multi-wrapping body in the range of 5 to 100 g / 15 mm.

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