JP2002264934A - Laminated packaging material for paper container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper container packaging material for filling and packaging a liquid food which is provided with a superior extrusion laminating characteristic and its converting characteristic necessary in producing a packaging material, is easily produced, is quickly heat sealed, whose heat seal strength is satisfactory, which is sealed satisfactory with no influence of the temperature of filled contents, and has a smell keeping or quality maintaining characteristic. SOLUTION: This paper container packaging material includes at least each of the constituent outermost thermoplastic material layer, paper base material layer, barrier layer, and innermost thermoplastic material layer laminated in the order. The innermost layer contains at least a wire form low density polyethylene having a narrow spread of molecule weight with such characteristic parameters as an average density of 0.900-0.915, a peak melting point of 88-103 deg.C, a melt-flow index of 5-20, a swelling ratio of 1.4-1.6, and a laminate thickness of 20-50 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging material for paper containers suitable for filling and packaging liquid foods. More specifically, a continuous paper packaging material is formed into a tube by applying a vertical line seal in the longitudinal direction, and the tube-shaped packaging material is filled with a filling material such as juice, tea, liquid dairy product, and the like. Brick-shaped paper packaging container obtained by applying a horizontal line seal at predetermined intervals in the transverse direction of the shape-like packaging material and cutting the packaging material along the horizontal line sealing portion, and cutting the paper-made packaging material into a predetermined shape Then, a blank sealed in the vertical direction of the container is obtained. After sealing the bottom of the blank, the material to be filled with the liquid product is filled from the upper opening, and the top is sealed. The present invention relates to a packaging material for a paper container suitable for filling and packing a liquid food in a packaging container.

[0002]

2. Description of the Related Art Packaging containers for milk, juice or other beverages are produced, for example, by forming a folded line of paper / plastic laminate into a tube by means of a longitudinal vertical line seal. The packing material is filled with the material to be filled, and a horizontal line seal is applied in the transverse direction of the tubular packaging material. First, it is formed into a cushion-shaped or pillow-shaped primary shape. It is cut individually at intervals and folded along the fold line to form the final shape. Examples of the final shape include a brick (parallel hexahedron), a polygonal prism exceeding a square, a hexagonal prism, an octagonal prism, a ten-prism prism, and a tetrahedron shape having four triangular surfaces.

Further, in the case of a gable-top (roof type) paper packaging container, the paper packaging material is cut into a predetermined shape, blanks sealed in the vertical direction of the container are obtained, and the bottoms of the blanks are sealed in a filling machine. It is obtained by filling milk, juice or other beverage filling material from the upper opening later and sealing the upper part. In these paper containers, the innermost layer of the packaging material corresponding to the horizontal line seal portion and / or the vertical line seal portion is heat-sealed with the other innermost layer or outermost layer.

[0004]

The packaging laminate used in the conventional paper packaging container product is a low-density polyethylene (LDPE) / printing ink layer / paper (fibrous) obtained by a high-pressure method.
Base layer / LDPE / Aluminum foil (Al) / LDPE / LD
PE, LDPE / printing ink layer / paper base layer / LDPE /
LDPE, printing ink layer / LDPE / paper base layer / LDP
E / LDPE, LDPE / printing ink layer / paper base layer / LDPE / Al / polyester (PET), and the like are known, and are currently in widespread use.

However, the LD used here is
PE is a high-pressure low-density polyethylene, and the low-molecular-weight components contained in the innermost high-pressure low-density polyethylene migrate to the contents in the paper container, and the taste of the contents changes when stored for a long time. There is fear. Further, in an ethylene-α-olefin copolymer obtained using a Ziegler catalyst,
The sealing temperature is high and the processability is inferior. If a lubricant is added to improve the processability, the lubricant transfers to the contents and reduces the taste.

In the innermost layer, a linear low density polyethylene (LLD)
A paper container using PE has been proposed (Japanese Patent Laid-Open No. Sho 62).
-78059, JP-A-60-99647, etc.). Excellent in impact strength, tear strength, low temperature brittleness, heat seal strength, hot tagging properties, etc. However, compared to LDPE, EVA and ionomers, it is said that the heat-sealing start temperature is somewhat higher, so that the converting properties are inferior.

On the other hand, a paper container using an ethylene-α-olefin copolymer (so-called metallocene PE, mLLDPE) polymerized by using a metallocene catalyst in the innermost layer has been proposed (Japanese Patent Application Laid-Open No. 148895/1995). JP-A-8-337237, JP-A-9-29868, JP-A-9-52299, JP-A-9-76435, JP-A-9-142455, JP-A-9-86537, 9-7
No. 6375). This metallocene PE is known to have good low-temperature sealability, good processability of the film, and good hygiene due to its narrow molecular weight distribution, and can be applied to containers (WO93 / 08221, magazine "Plastic", vol. 44, 1). No. 60, Magazine "Chemical Economics" Vol. 39 No. 9 No. 4
8 pages, magazine "Plastic", Vol. 44, No. 10, page 83). However, even if the metallocene PE has a low-temperature sealing property, not all metallocene PEs can necessarily reduce the leakage of the contents from the paper container obtained by heat sealing, and the packaging material It does not show good performance in the extrusion lamination properties required for production and the converting properties thereby.

When the liquid food is, for example, a citrus fruit juice, etc., in addition to the flavor preserving properties such as flavor and flavor,
Oxygen barrier properties are required. The liquid foods penetrate oxygen through the carton walls, thereby losing their nutritional value. It is common to add an aluminum foil layer to the laminate material to reduce oxygen ingress into the carton and minimize degradation of nutrients such as vitamin C. Also, various attempts have been made to develop practical alternatives to aluminum foil. It has excellent oxygen, gas and aroma barrier properties, yet is easily disposable after use. It has been conventionally proposed to use a vapor deposited layer of an inorganic oxide as a packaging material for paper containers (Japanese Utility Model Publication No. 5-28190, Japanese Patent Application Laid-Open No. 8-500688, and Japanese Patent Application Laid-Open No. 6-93120). With such a gas (oxygen) blocking material, a paper container having a scent-retaining property or a quality-retaining property can be provided.

In the process of filling and packaging a liquid food, the joint to be sealed is formed by extruding the hot melt resin in the extrusion laminate at that temperature, the surface of which is contaminated by oxides. The surface is contaminated by residual liquid food. Such contaminants,
It is important in an actual manufacturing process to optimally seal the packaging materials having foreign substances present on the surface, and it is difficult to obtain an optimal seal with the above-mentioned conventional packaging material for liquid food paper containers. In particular, a packaging material including a continuous paper base layer with a fold line is overlapped with the innermost layer at one end of the packaging material and the outermost layer at the other end of the packaging material and longitudinally sealed to form a longitudinal direction. The liquid food to be filled is filled into the tube-shaped packaging material, and the innermost layers of the tubular packaging material are joined to each other below the liquid level of the liquid food to form a predetermined space in the transverse direction. Filling and packaging method in which a horizontal line seal is applied every time, the packaging material is cut along the horizontal line seal portion, formed into a primary shape, folded along a fold line, for example, formed into a brick-like final shape to obtain a packaging container In such a case, since the liquid food is bonded under the liquid surface, the liquid food always remains, and the surface is contaminated, and it is difficult to obtain a good seal.

[0010] Further, since the liquid food to be filled has various quality and characteristics with respect to temperature, the temperature conditions at the time of filling and packaging this food vary widely, thus affecting the temperature of the filling contents. As a result, the sealing temperature varies over a wide range in the filling and packaging process. However, since the heat-adhesive resin in the conventional packaging material does not necessarily have a wide range of sealing properties, a good seal cannot be obtained due to the influence of the temperature of the filling contents.

[0011]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above background, and an object of the present invention is to improve the extrusion lamination characteristics required for the production of packaging materials and the converting characteristics thereby. It has excellent performance, is easy to manufacture packaging materials, can be quickly heat-sealed, enables tougher sealing strength, and obtains a good seal without being affected by the temperature of the filling contents. It is an object of the present invention to provide a packaging material for a paper container for filling and packaging a liquid food, which can provide a paper container having a fragrance retaining property or a quality maintaining property.

[0012]

The above object is achieved by the present invention. That is, the packaging material for a paper container according to the present invention includes at least the constituent layers of the outermost thermoplastic material layer, the paper base material layer, the barrier layer, and the innermost thermoplastic material layer, and these layers are laminated in the above order. What is claimed is: 1. A packaging material for a paper container, comprising: a layer of the innermost thermoplastic material containing at least linear low-density polyethylene having a narrow molecular weight distribution;
900 to 0.915, preferably 0.905 to 0.91
Average density of 0, 88-103 ° C, preferably 93-10
3 ° C. peak melting point, 5-20 melt flow index, 1.4-1.6 swelling ratio (Swellin)
g Ratio, SR) and characteristic parameters of a layer thickness of 20 to 50 μm, preferably 20 to 30 μm.

In a preferred embodiment of the present invention, the outermost thermoplastic material layer contains at least linear low-density polyethylene having a narrow molecular weight distribution, and is 0.900 to 0.92.
Average density of 5, 88 to 103 ° C, preferably 93 to 10
3 ° C. peak melting point, 5-20 melt flow index, 1.4-1.6 swelling ratio (SR) and 10
It has characteristic parameters of a layer thickness of 〜25 μm, preferably 10-20 μm. In another preferred embodiment of the invention, the adhesive layer between the barrier layer and the innermost thermoplastic material layer contains at least linear low density polyethylene having a narrow molecular weight distribution, 0.900 to 0.915,
Preferably an average density of 0.905 to 0.910, 88 to
A peak melting point of 103 ° C., preferably 93-103 ° C., 5
It has a melt flow index of ２０20, a swelling ratio (SR) of 1.4-1.6 and characteristic parameters of layer thickness of 2-15 μm. In yet another preferred embodiment of the present invention, the adhesive thermoplastic material layer between the paper substrate layer and the barrier layer contains at least a linear low density polyethylene having a narrow molecular weight distribution, 0.890-0.
925 average density, 88-103 ° C., peak melting point of 93-103 ° C., melt flow index of 10-20,
Swelling ratio (SR) of 1.4-1.6 and 10-2
It has characteristic parameters of a layer thickness of 5 μm, typically 10-20 μm.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes how to implement the present invention. The packaging material for a paper container according to a preferred embodiment of the present invention includes an outermost thermoplastic material layer, a paper base material layer, an adhesive thermoplastic material layer, for example, a barrier layer made of aluminum, and an innermost thermoplastic material layer. At least, each of these layers is laminated in the above order. The paper substrate that can be used in the present invention is usually made of kraft pulp, and requires excellent strength and low water absorption.
The types are bleached paper (FBL), unbleached paper (UBL),
There are bleached and unbleached laminated paper (DUPLEX), clay-coated paper, and multilayer laminated paper (MB), and any of them in the present invention.

[0015] The adhesive resin layer used for laminating the laminated packaging material of the present invention contains LLDPE and ethylene-vinyl acetate having specific characteristic parameters containing at least linear low-density polyethylene having a narrow molecular weight distribution. It consists of one selected from a polymer (EVA) and an ionomer. This LLDPE, in a preferred embodiment of the present invention, contains at least a linear low-density polyethylene having a narrow molecular weight distribution as an adhesive layer between the barrier layer and the innermost thermoplastic material layer. With an average density of .915, a peak melting point of 88-103 ° C., a melt flow index of 5-20, a swelling ratio (SR) of 1.4-1.6 and a layer thickness of 2-15 μm. is there. By using LLDPE, the innermost thermoplastic material layer can be satisfactorily bonded to various barrier layers even when extruded at a high temperature. Also, this LLDPE
In yet another preferred embodiment, the adhesive thermoplastic material layer between the paper substrate layer and the barrier layer contains at least linear low density polyethylene having a narrow molecular weight distribution, Average density, 88-103
C., peak melting point of 10 DEG C., melt flow index of 10-20, swelling ratio (SR) of 1.4-1.6 and 10
It has characteristic parameters of a layer thickness of ２５25 μm. By using this LLDPE, the extruded lamination characteristics and the converting characteristics due to the extruded lamination characteristics during the production of the packaging material are excellent, so that the production of the packaging material lamination can be performed very well. Furthermore, an ethylene-vinyl acetate copolymer (EVA) having adhesiveness to metal by extrusion lamination processing
Alternatively, using an ionomer (IO) synthetic resin in which the molecules of an ethylene-vinyl methacrylate copolymer are crosslinked with metal ions, these film-forming layers can be laminated as an adhesive layer. It is preferable to use an adhesive layer having a thickness of about 10 to 50 μm. Preferably, the adhesive layer is EVA or IO having a layer thickness of 10 to 18 μm.

The packaging material for a paper container according to the present invention is formed on the outer surface of an ink layer by printing or an outer resin layer having a sealing property provided on the outer surface of a semi-material on which the outermost resin layer is not yet laminated. At least a coated ink layer. Inks include aqueous or oil-based inks for flexographic printing, oil-based inks for gravure printing, curable inks for offset printing, and the like. In a preferred embodiment of the packaging material for paper containers of the present invention, the ink layer is the ink layer. And a component (for example, an imine-based component) that is partially common to the component included in the anchor agent layer that adheres to the adhesive layer.

The packaging material for a paper container of the present invention includes a thermoplastic material layer laminated on the outer surface of the packaging material. This material resin layer is, for example, a polyolefin resin such as polyethylene, polypropylene, and ethylene copolymer. In addition to low density polyethylene (LDPE) conventionally used, resistance to contents (oil resistance, acid resistance, etc.) , Low-density polyethylene (LLDP) with excellent penetration resistance
E), a medium-density polyethylene or a co-extruded film containing polyethylene. In a preferred embodiment of the invention, the outermost thermoplastic material layer contains at least a linear low density polyethylene having a narrow molecular weight distribution,
Average density of ０．９0.925, peak melting point of 88 to 103 ° C., preferably 93 to 103 ° C., melt flow index of 5 to 20, swelling rate of 1.4 to 1.6 (S
R) and those having characteristic parameters of a layer thickness of 10 to 25 μm, preferably 10 to 20 μm.

In an embodiment of the packaging material for a paper container according to the present invention,
A barrier layer is provided on the inner laminate of the packaging material. The barrier layer is made of at least one selected from an aluminum foil, a metal / inorganic oxide thin film, an ethylene vinyl alcohol copolymer layer (EVOH layer), a nylon layer, a polyvinylidene chloride film, and a polyvinylidene chloride coated film.
Here, as the vapor-deposited film of the inorganic oxide as the barrier layer, for example, a thermoplastic resin film having a thickness of about 10 to 30 μm of polyolefin, nylon, polyester, polyvinyl alcohol, or the like is used for silicon oxide, tin oxide, or oxide. Thickness of 100 to 5000 by inorganic oxide such as zinc, indium oxide, titanium oxide, aluminum oxide
A thin film layer having a thickness of preferably about 200 to 1,000 is formed by vacuum deposition, sputtering, chemical vapor deposition, plasma chemical vapor deposition (PCVD), or the like.

As aluminum constituting the aluminum foil or aluminum thin film layer of the barrier layer, ordinary aluminum metal can be used. In this embodiment, as a method for forming the aluminum thin film layer, it can be formed by forming a vapor deposition film by a vacuum vapor deposition method such as an ion beam method or an electron beam method, a sputtering method, or the like. In the above, as the thickness of the aluminum thin film layer, in order to obtain a sufficient light-shielding property, usually,
It is preferably about 10 nm to 200 nm, and in particular,
In the present invention, about 20 to 150 nm is desirable. In the above description, as the thickness of the aluminum thin film layer increases, the total light transmittance decreases.
In nm, the total light transmittance is 0%. In the present invention, the thickness of the aluminum thin film layer can be adjusted according to the final packaging form, the presence / absence of the printed layer, the position where it is present, and the like, and the required physical properties.

The barrier layer that can be used in the present invention also includes a barrier film. The resin film constituting this may be a resin film capable of forming a barrier resin layer such as EVOH or polyvinyl alcohol, a vapor-deposited film of inorganic oxide, or a vapor-deposited film of aluminum. Polyester films, such as polyester films, polybutylene terephthalate films, 6 nylon films, 66 nylon films, 610 nylon films,
612 nylon film, 11 nylon film, 12
Nylon film, polyamide resin film such as polyamide film by condensation of meta-xylene diamine and dibasic acid, polycarbonate resin film, polyolefin resin film such as polyethylene, polypropylene, etc., polyvinyl alcohol resin film , Ethylene-vinyl acetate copolymer film, polyvinyl chloride resin film, polyvinylidene chloride resin film, polystyrene resin film, poly (meth) acrylic resin film, polyacrylonitrile resin film, polyacetal resin Films, fluorine-based resin films, and other resin films can be used.

As the resin film, any one of an unstretched film and a stretched film stretched in a uniaxial or biaxial direction can be used.
The thickness of the film is 5 μm to 10 μm.
It is desirably about 0 μm, preferably about 10 μm to 30 μm. In the present invention, the film of the resin may be, if necessary, optionally subjected to a known pretreatment such as application of a silane coupling agent or the like, primer treatment, sandplast treatment, etc. The surface of the film can be adjusted.

Next, in the present invention, examples of the inorganic oxide constituting the inorganic oxide thin film layer include silicon oxide (SiOx), aluminum oxide, indium oxide, and the like.
Tin oxide, zirconium oxide, or the like can be used. Furthermore, in the present invention, the inorganic oxide may be a mixture of silicon monoxide and silicon dioxide, or a mixture of silicon oxide and aluminum oxide.

In the present invention, as a method of forming a thin layer of inorganic oxide, a vapor deposition method such as an ion beam method and an electron beam method, a sputtering method, a plasma chemical vapor deposition method (PCVD method) and the like are used. It can be formed by forming a film. In the above description, the thickness of the inorganic oxide thin film layer is usually preferably about 10 nm to 200 nm in order to obtain a sufficient barrier property, and particularly preferably about 20 to 150 nm in the present invention. . In the above, the thickness of the inorganic oxide thin film layer,
When it exceeds 150 nm, especially when it exceeds 200 nm,
Cracks and the like are likely to be formed in the thin film layer of the inorganic oxide, and there is a risk that the barrier property is reduced by the warpage, and the cost of the material is increased. The above-mentioned barrier layer is preferably 5 to 1
5μm thin layer, 5cc / m ² 24hratm (23 ℃ 85% RH)
Has an oxygen permeability of less than.

In the present invention, the innermost thermoplastic material layer is
Containing at least a linear low density polyethylene having a narrow molecular weight distribution, an average density of 0.900 to 0.915, preferably 0.905 to 0.910, 88 to 103 ° C,
Preferably a peak melting point of 93-103 ° C, a melt flow index of 5-20, a swelling ratio (Swelling Ratio, SR) of 1.4-1.6 and 20.
It has characteristic parameters of a layer thickness of ５０50 μm, preferably 20-30 μm. As such an innermost thermoplastic material layer, for example, a linear low-density polyethylene (mLLDP) having a narrow molecular weight distribution polymerized by using a metallocene catalyst is used.
There is a blend polymer containing at least E). Examples of the mLLDPE include a catalyst obtained by combining a metallocene complex such as a catalyst obtained by combining zirconocene dichloride and methylalumoxane with alumoxane;
That is, an ethylene-α-olefin copolymer obtained by polymerization using a metallocene catalyst can be used. The metallocene catalyst is a so-called multi-site catalyst in which the active sites are non-uniform and the current catalyst is called a single-site catalyst because the active sites are uniform.

As the resin of mLLDPE, specifically,
The brand name "Cannel" manufactured by Mitsubishi Chemical Corporation, the brand name "Evolu" manufactured by Mitsui Petrochemical Industry Co., Ltd., the brand name "EXACT" manufactured by EXXON CHEMICAL, USA, United States, Dow
An ethylene-α-olefin copolymer polymerized using a metallocene catalyst such as “Affinity” (trade name) or “ENGAGE” (trade name) manufactured by DOW CHEMICAL can be used. .

In the present invention, resins other than the mLLDPE resin can be used as long as the above characteristic parameters are exhibited. Further, since it is difficult to obtain the above-mentioned characteristic parameters using mLLDPE alone, other polymer components can be blended. Here, “other polymer” means
For example, polyethylene, polypropylene, polyolefin resins such as ethylene copolymers, and thermoplastic resins such as polyester resins. In addition to low density polyethylene (LDPE) conventionally used, resistance to contents (oil resistance, Linear low density polyethylene (LLDPE) excellent in acid resistance, penetration resistance, etc.), and coextruded films containing medium density polyethylene and polyethylene. The density of the low density polyethylene to be blended is 0.91
Is a ~0.93g / cm ^3. The molecular weight is 1 × 10 ²
To 1 × 10 ^8, as the melt flow rate (MFR) is 0.1 to 20 g / 10min. In addition, basically no additive is used, but depending on the application, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, antiblocking agents, flame retardants, inorganic and organic fillers, paints, Various additives such as a pigment may be appropriately added.

The metallocene catalyst of mLLDPE is characterized in that the polymerization active site is single (single site),
An ethylene-α-olefin copolymer polymerized using this catalyst has excellent properties that cannot be obtained with an ethylene-α-olefin copolymer obtained using a multisite catalyst found in a conventional Ziegler catalyst. A typical single-site catalyst is a metallocene catalyst, a so-called Kaminski catalyst. The metallocene catalyst is a catalyst comprising a metallocene-based transition metal compound and an organoaluminum compound.Examples of the metallocene-based transition metal compound include a zirconium-based compound, a titanium-based compound, and a silica-based compound. Not limited. Examples of the organoaluminum compound include alkylaluminum and a chain or cyclic aluminoxane, but the present invention is not limited thereto. Examples of the polymerization method include a solution polymerization method, a gas phase polymerization method, a slurry polymerization method, and the like, but none of them is particularly limited.

As the α-olefin which is a comonomer copolymerized with ethylene, butene-1, hexene-1, 4
-Methylpentene-1 and octene-1 are listed. These α-olefins may be used alone or as a mixture of two or more.

The mixing ratio of ethylene and α-olefin is 1 to
20% by weight is preferable, and the density of the polymerized ethylene-α-olefin copolymer is 0.900 to 0.915 g.
/ Cm ³ is desirable, more preferably 0.905 to
0.910 g / cm ³ . If it is less than 0.900 g / cm3, the roll release property and the slip property of the film at the time of film formation become poor. Also, 0.915
If the density is higher than g / cm3, the flexibility and low-temperature sealing property of the film are inferior, and the sealing property is reduced. The molecular weight is 1 × 10 ³ to 1 × 10 ⁶ , and the melt flow rate (MFR) is 3.0 to 30 g / 10 min, more preferably 10 to 20 g / 10 min. The peak melting point is 88 to 103 ° C, preferably 93 to 103 ° C.
° C. In addition, various antioxidants, ultraviolet absorbers, antistatic agents, lubricants, antiblocking agents, flame retardants, inorganic and inorganic fillers, dyes, pigments, etc. are appropriately added to the ethylene-α-olefin copolymer. May be. The low-density polyethylene only needs to be obtained using a conventional multi-site catalyst that is a Ziegler catalyst, and there is no particular limitation on the type of the catalyst or the polymerization method.

In the packaging material for paper containers of the present invention, the innermost layer contains at least linear low-density polyethylene having a narrow molecular weight distribution, and has an average density of 0.900 to 0.915, preferably 0.905 to 0.910. , 88 to 103 ° C,
Preferably a peak melting point of 93-103 ° C, a melt flow index of 5-20, a swelling ratio (Swelling Ratio, SR) of 1.4-1.6 and 20.
As mentioned above, it has a characteristic parameter of a layer thickness of ５０50 μm, preferably 20-30 μm. As such an innermost thermoplastic material layer, as described above, there is an ethylene-α-olefin copolymer polymerized using a metallocene catalyst. In a preferred embodiment of the present invention, an ethylene-α-olefin copolymer polymerized using a metallocene catalyst and a low-density polyethylene polymerized using a multi-site catalyst can be used. The layers other than the innermost layer of the paper container are not particularly limited.

The compounding ratio of the components necessary for the ethylene-α-olefin copolymer obtained by polymerization with a metallocene catalyst to maintain sealing properties such as sealing properties and impact resistance is at least 50% by weight, preferably at least 50% by weight. 55 to 75% by weight, more preferably 55 to 65% by weight. Other than the above range, especially 5
If it is less than 0% by weight, good sealing properties and impact resistance cannot be obtained,
On the other hand, if the content is 65% by weight, the workability and the lamination property are undesirably reduced.

Next, the blending ratio of low-density polyethylene obtained by polymerization with a multi-site catalyst required to increase the melt tension such as film formability is preferably 50% by weight or less, more preferably 45 to 25%. %, More preferably 45 to 35% by weight. Exceeding the above range is not desirable because good sealing properties and impact resistance cannot be obtained.

As a method for adjusting these resins, any method can be adopted. For example, after blending the respective components and mixing them with a blender, a mixer, etc., the mixture is melted with a twin-screw kneading extruder, a mixing roll, a Banbury mixer, or the like. Any of a kneading method and a dry blending method of mixing pellets may be used. This embodiment is characterized by comprising an ethylene-α-olefin copolymer obtained by polymerization with a metallocene catalyst and low-density polyethylene obtained by polymerization with a multi-site catalyst. Therefore, it is a polymer having a narrow molecular weight distribution (Mw / Mn ≦ 3) and a narrow composition distribution, which are characteristics of an ethylene-α-olefin copolymer polymerized by a metallocene catalyst, and having a well-structured molecular structure. Maintains excellent strength, impact strength, tear strength, and low-temperature sealability, and increases the molecular entanglement due to the high melt tension, which is one of the characteristics of low-density polyethylene polymerized with a multisite catalyst. . Therefore,
The film formability and the impurity sealing property can be improved. In addition, since the film formability is good, the concentration of additives such as a lubricant can be reduced, so that the obstacle to the sealability is reduced, the characteristics of the sealability can be maximized, and the content by the additive can be further improved. It has little effect on taste and ingredients and is excellent in sealability, so that an excellent paper container which does not impair the protection of contents can be obtained.

In the field of liquid food filling, which embodies the present invention, a continuous paper packaging material is formed into a tube in the longitudinal direction, and a filling material such as fruit juice, tea, liquid dairy product is filled in the tubular packaging material. A brick-shaped paper packaging container obtained by applying a horizontal line seal at predetermined intervals in the transverse direction of the tubular packaging material and cutting the packaging material along the horizontal line sealing portion, and a paper packaging material obtained by a predetermined method. A gable-top shape (roof type) obtained by cutting into a shape, obtaining a blank sealed in the vertical direction of the container, sealing the bottom of the blank, filling the filling of the liquid product from the upper opening, and sealing the upper portion Paper packaging containers.

The paper container of the present invention to be molded can be assembled into a processed paper container (one-piece type, two-piece type, three-piece type, etc.), a composite can, an insert-molded container, a double container, or the like. In this case, the packaging material is punched out according to a development view of the composite paper container, processed into a ruled line, and then folded along the ruled line and sealed to form various types of paper containers. At this time, as a sealing method, there are a heat seal, a frame seal, a hot air seal, an ultrasonic seal, a high frequency seal and the like. In addition, in a filling machine, these laminates are supplied in a roll shape, a sleeve shape or a cup shape, and after filling the contents,
A paper container is formed by being sealed using the various sealing methods described above.

Next, a method for producing a packaging material for a paper container according to the present invention will be described. Laminating ordinary packaging materials,
For example, wet lamination, dry lamination, solventless dry lamination, extrusion lamination, T-die coextrusion molding, coextrusion lamination, inflation, etc. be able to. In the present invention, when performing the above-mentioned lamination, if necessary, for example, corona treatment, pretreatment such as ozone treatment can be performed on the film, and, for example,
Isocyanate-based (urethane-based), polyethyleneimine-based, polybutadiene-based, organic titanium-based anchors
Polyurethane, polyacrylic, polyester, epoxy, polyvinyl acetate,
Known anchor coating agents, adhesives and the like, such as cellulose and other laminating adhesives, can be used.

As described above, in the present invention, various laminating methods are possible. In the laminated packaging material according to the present invention, when the packaging material is manufactured by using the extrusion lamination method, More advantages according to the present invention can be obtained. This is because, in a preferred embodiment according to the present invention, the resin to be extruded and laminated has characteristic parameters that are optimally adjusted in average density, peak melting point, melt flow index, swelling ratio and layer thickness, so that This is because they exhibit extrusion laminating properties in the production of materials and good converting properties due to them.

In the method for producing a packaging material, an extruded
As the extruded resin constituting the adhesive resin layer when the outermost thermoplastic material layer constituting the packaging material according to the present invention,
In addition to the materials used in the adhesive layer, the adhesive thermoplastic material layer, and the innermost thermoplastic material layer, for example, polyethylene, ethylene-α-olefin copolymer, polypropylene, polybutene, polyisobutene, polyisobutylene, polybutadiene , Polyisoprene, an ethylene-methacrylic acid copolymer, or a copolymer of ethylene and an unsaturated carboxylic acid such as an ethylene-acrylic acid copolymer, or an acid-modified polyolefin resin obtained by modifying them.
Ethylene-ethyl acrylate copolymers, ionomer resins, ethylene-vinyl acetate copolymers, and the like can be used. When the dry laminating method is used, the adhesive constituting the adhesive layer at that time is as follows:
Specifically, 2 used in dry laminating etc.
Liquid-curable urethane adhesive, polyester urethane adhesive, polyether urethane adhesive, acrylic adhesive, polyester adhesive, polyamide adhesive, polyvinyl acetate adhesive, ethoxy adhesive, rubber A system adhesive, others, and the like can be used.

FIG. 1 shows an example of the packaging material according to the present invention. In this example, the outermost thermoplastic material layer 21, paper base layer 22, adhesive thermoplastic material layer 23, barrier layer 24, adhesive layer 2
5, each of the constituent layers of the innermost thermoplastic material layer 26. These packaging materials are, for example, fold lined packaging materials,
This packaging material is formed into a tube shape by a longitudinal vertical line seal, the material to be filled is filled in the tube-shaped packaging material, and a horizontal line seal is applied in a transverse direction of the tubular packaging material. It is formed into a shape or a pillow-like primary shape, and when the packaging material is a band shape, it is individually cut at regular intervals and folded along a fold line to form a brick (parallel hexahedron) final shape.

FIG. 2 shows an outline of an example of a filling and packaging machine using the laminated packaging material according to the present invention. In the filling machine shown in this example, the packaging material web 1 having a thermoplastic material layer as the innermost layer is unwound and rolled, and the inside of the filling machine is conveyed by rollers, and the strip tape 2 is stripped by the strip tape applicator 3. The packaging material web is joined to one end of the packaging material web, sterilized by passing the packaging material web through the sterilizing agent tank 4, the sterilizing agent is removed by an air knife 5, and formed into a tube by a forming roller 6, and the tube is formed. The liquid sealing material according to the present invention is filled with liquid food from the filling pipe 7 and sealed in the vertical direction of the tube by the vertical line sealing element 8 while feeding the tube downward by a length corresponding to one packaging container. , And heat sealed in the transverse direction, and at the same time, continuously formed into a pillow-shaped filled packaging container 12, The cut portion of the seal zone of the pillow-shaped packing and filling container connected downstream is cut off, separated into individual packing and filling containers 13 by a knife or the like, and the upper and lower flaps of the separated pillow-shaped container 14 are bent, and the final holder 14 is used. It is formed into a packaging and filling container 11 in the final form.

In the present invention, another example of manufacturing a paper container will be described. A blank plate for a paper container which has been subjected to a crease processing to manufacture a paper container having a predetermined shape is punched out, and then the edges of the blank plate are overlapped. A film of an ethylene-α-olefin copolymer polymerized using a metallocene catalyst as a heat-sealing film on the inner surface side of the polymerization end portion and a heat-sealing film on the outer surface side are welded. Then, a weld is formed to produce a sleeve. Next, the sleeve is mounted on a filling machine, and the bottom portion is folded along a predetermined ruled line and heat-sealed by hot-air treatment to form a bottom portion, and then the contents are filled from the opening at the top portion, Thereafter, the top portion is folded along a predetermined ruled line and heat-sealed by hot air treatment, for example, to form a top portion in the shape of a gabelle top, and to manufacture a packed and packed product. Can be. The above-mentioned examples are merely examples of the packaging container according to the present invention, and the present invention is not limited thereto.

The packaging container according to the present invention includes, for example, milk, lactic acid bacteria drink, liquid soup, fruit juice drink, barley tea, green tea,
Liquid products such as Woolong tea, alcoholic beverages, seasonings, pharmaceuticals, cosmetics, paints, adhesives, inks, developers, etching solutions, etc. can be applied to filling and packaging,
Preferably, it is a liquid food.

[0043]

EXAMPLES The present invention will be specifically described with reference to the following examples. <Example 1> A linear low-density polyethylene (mLLDPE) having a narrow molecular weight distribution polymerized with a metallocene catalyst and a low-density polyethylene obtained by a high-pressure method were blended on one surface of an aluminum foil having a thickness of 9 µm to obtain an average density of 0.910. 97
° C peak melting point, 15 melt flow index,
An adhesive layer having a swelling ratio of 1.5 and a layer thickness of 13 μm is melt-extruded and blended with a low molecular weight linear low density polyethylene (mLLDPE) polymerized with a metallocene catalyst and a low density polyethylene produced by a high pressure method. 0.9
07 average density, 96 ° C. peak melting point, 14 melt flow index, 1.5 swelling ratio and 25 μm
An innermost thermoplastic material layer having a layer thickness of m is laminated to form a laminated film composed of an aluminum foil / adhesive layer / innermost thermoplastic material blend layer. At the same time, low-density polyethylene (density = 0.920 g / cm ³ , MI = 5.
1) 20 μm thick paper base material (basis weight = 320 g / m ² )
The outermost thermoplastic material layer is laminated by extrusion coating at an extrusion temperature of 330 ° C. Then, the low-density polyethylene / paper base material and the aluminum foil side of the aluminum foil laminate are blended with a metallocene-catalyzed linear low-density polyethylene (mLLDPE) having a narrow molecular weight distribution and low-density polyethylene produced by a high-pressure method. The adhesive thermoplastic material layer was melt extruded with an average density of 0.920, a peak melting point of 99 ° C., a melt flow index of 17, a swelling ratio of 1.5, and a layer thickness of 12 μm, and laminated. A continuous long laminated packaging material having the laminated configuration shown in FIG. 1 is obtained. Using this packaging material, a brick-shaped liquid food-filled package is obtained by the filling machine shown in FIG. The sealable temperature range of the vertical line seal in the obtained package and the filling machine, the allowable temperature range of the horizontal line seal, and the seal strength are evaluated.

<Example 2> In Example 1, instead of the low-density polyethylene of the outermost thermoplastic material layer by the high-pressure method, a linear low-density polyethylene (mLLDPE) having a narrow molecular weight distribution polymerized with a metallocene catalyst and the high-pressure method were used. Performed with the exception of blending with low density polyethylene to use a thermoplastic material having an average density of 0.915, a peak melting point of 95 ° C., a melt flow index of 17, a swelling factor of 1.5, and a layer thickness of 18 μm. Packaging material as in Example 1,
Further, a brick type paper container is manufactured. Further, the obtained paper container and packaging and filling are evaluated in the same manner as in the examples. The pattern color printed on the outer surface of the paper layer can be seen from the outside with a clear and glossy through this transparent outermost thermoplastic material layer

<Example 3> In Example 1, instead of aluminum foil, a silicon oxide (SiOxC) was formed on a 8 μm polyester film by plasma-enhanced chemical vapor deposition.
A packaging material and a brick-type paper container are prepared in the same manner as in Example 1 except that a barrier film on which y) is deposited is used. Further, the obtained paper container and packaging and filling are evaluated in the same manner as in the examples.

<Comparative Example 1> In Example 1, as the innermost thermoplastic material layer and the adhesive layer, low-density polyethylene (density = 0.920 g / cm ³ , MI = 5.
A packaging material and a brick-type paper container are produced in the same manner as in Example 1 except that 1) is used. Further, the obtained paper container and packaging and filling are evaluated in the same manner as in the examples.

Comparative Example 2 In Example 1, a low-density polyethylene (density = 0.9) was used as an adhesive layer by a high-pressure method.
20 g / cm ³ , MI = 5.1), and a packaging material in the same manner as in Example 1 except that a film in which low-density polyethylene and an adhesive resin were bonded by an inflation method as an innermost thermoplastic material layer was used. Then, a brick type paper container is manufactured. Further, the obtained paper container and packaging and filling are evaluated in the same manner as in the examples.

Comparative Example 3 In Example 1, instead of the innermost layer of the thermoplastic material, a linear low-density polyethylene (mLLDP) having a narrow molecular weight distribution polymerized with a metallocene catalyst was used.
E) is blended with low density polyethylene by high pressure to yield a thermoplastic material having an average density of 0.915, a peak melting point of 95 ° C., a melt flow index of 17, a swelling ratio of 1.3 and a layer thickness of 18 μm. A packaging material and a brick-type paper container are prepared in the same manner as in Example 1 except that the paper container is used. Further, the obtained paper container and packaging and filling are evaluated in the same manner as in the examples.

In Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3, the sealable temperature range of the vertical line seal, the sealable temperature range of the horizontal line seal, and the seal strength are evaluated. As a result, it was found that the example was superior to the comparative example. For example, comparing Example 2 and Comparative Example 2,
In the second embodiment, the sealable temperature range of the vertical line seal is 80.
%, It shows good sealing performance by spreading to the low temperature side, and demonstrates that the allowable temperature range of the horizontal line sealing has been expanded by 20% or more, making the sealing at the time of packing filling easier and simpler. Furthermore, the sealing strength of the horizontal line seal was improved by 30 to 40% when comparing Example 2 with Comparative Example 2. In addition, the sealability of foreign substances in the innermost thermoplastic material layer (the ability to seal well even if foreign substances such as oxides and residual foods exist between the innermost thermoplastic material layers at the locations to be sealed) evaluate. As a result, it is excellent in the impurity sealing property.

[0050]

According to the present invention demonstrated in the above embodiment, the following effects can be obtained. Since the packaging material for a paper container of the present invention has the above-described configuration, the packaging material for a paper container has good performance in the extrusion lamination characteristics necessary for the production of the packaging material and the converting characteristics thereby. , Easy to manufacture packaging material, can be heat sealed quickly,
Enables a stronger seal strength, and obtains a good seal without being affected by the temperature of the filling content, that is,
The sealing property of impurities is improved and the sealing property is excellent. Also,
Has fragrance retention or quality retention properties. In addition, the sealable temperature range is widened at the time of packaging and filling, so that a good seal can be obtained at high or low temperature without being affected by the temperature of the filling contents. Since the temperature can be set lower than when using them, the thermal damage can be reduced even if a thin film layer of inorganic oxide, a thin film layer of aluminum, or the like is used for the barrier layer. Deterioration and the like can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a layer structure of an embodiment of a packaging material for a paper container of the present invention.

FIG. 2 is a schematic view of a filling machine that can be filled using the packaging material for paper containers of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Packaging material web 10 Seal jaw 11 Opposing jaw 21 Outermost thermoplastic material layer 22 Paper base material layer 23 Adhesive thermoplastic material layer 24 Barrier layer 25 Adhesive resin layer 26 Innermost thermoplastic material layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroaki Ogita 6-12 Kioicho, Chiyoda-ku, Tokyo F-term in Nippon Tetra Pack Co., Ltd. 3E060 BC01 BC04 DA20 DA21 EA03 EA13 4J100 AA02P AA04Q AA16Q AA17Q AA19Q CA01 CA04 DA13 DA24 DA36 DA42 FA10 JA59

Claims (4)

[Claims] Claims 1. An outermost thermoplastic material layer, a paper base material layer, a barrier layer, and an innermost thermoplastic material layer, each including at least each constituent layer,
A paper container packaging material comprising these layers laminated in the above order, wherein the innermost thermoplastic material layer contains at least linear low-density polyethylene having a narrow molecular weight distribution;
Average density of 0.915, peak melting point of 88-103 ° C.,
5-20 melt flow index, 1.4-1.6
Swelling ratio (SR) and a layer thickness of 20 to 50 μm. 2. The outermost thermoplastic material layer contains at least a linear low density polyethylene having a narrow molecular weight distribution,
Average density of 0.900 to 0.925, peak melting point of 88 to 103 ° C, melt flow index of 5 to 20,
Swelling ratio (SR) of 1.4-1.6 and 10-2
The packaging material for a paper container according to claim 1, which has a characteristic parameter of a layer thickness of 5 µm. 3. The adhesive layer between the barrier layer and the innermost thermoplastic material layer contains at least a linear low density polyethylene having a narrow molecular weight distribution, and 0.900 to 0.915.
An average density, a peak melting point of 88 to 103 ° C., a melt flow index of 5 to 20, a swelling ratio (SR) of 1.4 to 1.6 and a layer thickness of 2 to 15 μm. The packaging material for a paper container according to the above. 4. The adhesive thermoplastic material layer between the paper base material layer and the barrier layer contains at least linear low density polyethylene having a narrow molecular weight distribution, and 0.890 to 0.92.
Average density of 5, peak melting point of 88-103 ° C, 10-2
The packaging material for a paper container according to claim 1, having a melt flow index of 0, a swelling ratio (SR) of 1.4 to 1.6, and a characteristic parameter of a layer thickness of 10 to 25 m.