JP2009280239A - Liquid paper container and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid paper container able to prevent cracking of a barrier layer in a folded portion where stress concentrates when a liquid paper container is formed from a laminated material using an inorganic compound deposition film as a barrier film, and to provide a manufacturing method therefor. <P>SOLUTION: In the manufacturing method for the liquid paper container which uses the laminated body comprising the barrier film 4, the laminated body is obtained by processing a base paper 1 for formation of folding score lines C, and then laminating it with the barrier film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a paper container used for storing liquids such as beverages, seasonings, detergents, pharmaceuticals, and industrial chemicals, and more particularly to a liquid paper container having a high barrier property using an inorganic compound vapor-deposited film as a barrier film.

  Paper containers are widely used mainly for food. In particular, paper containers for storing liquids are easier to print directly on the container surface than plastic containers, and the development of recycling systems is progressing. For example, milk, beverages, seasonings, detergents, and pharmaceuticals Widely used for industrial chemicals.

  Conventionally, paper containers that are bent by ruled lines have an intermediate layer based on the base paper layer and polyethylene resin on both sides of the intermediate layer, depending on the nature and storage conditions of the contents stored inside the container. A laminated body provided with a thermal adhesive resin layer is used. Then, this laminate is punched into a predetermined shape according to the shape of the container, and simultaneously formed as blanks with ruled lines for bending, and the blanks are bent along the ruled lines, assembled, and the necessary parts are bonded. Thus, a paper container is formed (Patent Document 1).

  The paper container can be easily folded after use of the contents and can be incinerated, so that it is used in a wider range than before.

  Among the properties required for these liquid paper containers, the basics are the protection of the contents, and a heat-adhesive resin is applied to the surface of the paper container to prevent the leaching of liquid from the inside and the permeation of gas from the outside. In general, the top and bottom of the container are formed by bending the laminated paper and thermocompression bonding.

  As a conventional method for imparting the above-described content protection, which is one of the characteristics required for a liquid paper container, as a laminated body constituting the paper container, it is thin (about 7 μm) from the base paper. There is a method using a laminate of aluminum foils.

  The paper container can be easily folded after use, and can be incinerated, so it is easy to dispose of it. However, a laminated material with a layer made of metal foil such as aluminum foil was used to protect the contents. In some cases, when the contents were discarded after use and incinerated, the above metal remained as a lump and the incinerator could be damaged.

  On the other hand, when a metal foil such as an aluminum foil is removed, the gas barrier property is lowered and the storage stability of the contents is deteriorated, so that it is impossible to use the paper container in a wide range of applications.

  However, instead of the laminated material used in paper containers, it is changed to a metal foil such as an aluminum foil, and as a barrier film, a blank made of a laminated body in which an inorganic compound vapor-deposited plastic film for maintaining gas barrier properties is also interposed is used. When the container is molded in the same manner, since the metal foil having good moldability and shape maintaining property is not provided, not only the folding and assembling of the ruled line part is difficult, but also the inorganic compound vapor deposition layer of the ruled line part. It has been found that there is a case where the barrier property is deteriorated due to the small elongation of the film.

  Conventionally, several methods have been proposed as a method for preventing the generation of defects in the thin film at the stress concentration portion.

  For example, a synthetic resin layer and a printing ink layer are sequentially laminated on the upper surface of a base material mainly composed of a paper layer, and the same material is molded from a laminated material in which an intermediate layer, a barrier layer, and a sealant layer are sequentially provided on the lower surface of the base material. In the case of liquid paper containers, the main material of the barrier layer used to maintain the quality preservability of the contents was conventionally laminated with a highly barrier material such as aluminum foil. Various vapor-deposited thin films having excellent barrier properties are used (Patent Document 2).

  For example, an electron beam vacuum deposition method is used to deposit a deposition material made of a single metal of aluminum, a metal oxide such as aluminum oxide, or an inorganic oxide such as silicon oxide on a base material such as polyethylene terephthalate resin film (PET) in a vacuum environment. Thus, a vapor-deposited thin film is formed by evaporating by heating, and a laminated material having a high barrier property is produced.

  Aluminum vapor deposition film in which aluminum simple metal is vapor-deposited on a base material such as polyethylene terephthalate resin film (PET) is stable in quality from a thickness of about 500 mm (ohm strong), which is about the same as a conventional 7 μm aluminum foil. It has an oxygen gas barrier property. In addition, it has a water vapor barrier property, has a beautiful metallic luster in appearance, and has a weight of 1/100 to 1/200 that of aluminum foil. Flexural strength is protected by the elasticity of a substrate such as a polyethylene terephthalate resin film (PET), and the machinability is superior to aluminum foil.

  Next, the vapor deposition material which vapor-deposited by depositing the vapor deposition substance which consists of metal oxides, such as an aluminum oxide, or inorganic oxides, such as a silicon oxide, by electron beam irradiation on base materials, such as a polyethylene terephthalate resin film (PET), and vapor-deposited. A paper container made of a laminated material obtained by laminating a film is different from a paper container made of a laminated material obtained by laminating an aluminum vapor-deposited film obtained by vapor-depositing a conventional aluminum foil or aluminum simple metal on a base material such as polyethylene terephthalate resin film (PET), Since it is an oxide rather than a metal substance, it becomes possible to use a metal detector that enables the contents to be heated in a microwave oven or to detect a metal piece mixed as a foreign substance in the contents.

  As described above, there are various types of barrier layers, and each shows excellent performance, but the barrier layer formed by vapor deposition is made of a very thin film, so the part where stress is concentrated, such as a bent part, when forming a container There is a problem that cracks are likely to occur.

  Therefore, for the purpose of preventing cracks, conventionally, a low density polyethylene resin film (LDPE) is used as an intermediate layer serving as an adhesive for laminating a base material and a barrier layer, or the low density polyethylene resin film (LDPE) is used. ), Or by using a polyethylene terephthalate resin film (PET), depending on the shape of the container.

  In particular, when laminating a barrier layer of a base material and an aluminum foil, an ethylene methacrylic acid copolymer resin (EMAA) having polarity is used for an intermediate layer, and laminating is performed with no anchor.

  In addition, from a vapor deposition film produced by heating and vapor-depositing a base material and a metal oxide such as aluminum oxide or an inorganic oxide such as silicon oxide on a polyethylene terephthalate resin film (PET) by electron beam irradiation. In the case of the barrier layer, a polyester adhesive resin is used for the intermediate layer for laminating the base material and the barrier layer. As an example of the resin used for the intermediate layer, there is a linear low density polyethylene resin (LLDPE) polymerized by a single site catalyst (Patent Document 4).

  The linear low density polyethylene resin (LLDPE) polymerized by the single site catalyst has higher strength and higher strength than the conventional linear low density polyethylene resin (LLDPE) by taking advantage of the characteristics of the single site catalyst. It has transparency, low temperature heat sealability and toughness.

  LLDPE polymerized with a single-site catalyst has adhesion to polyethylene terephthalate resin film (PET), so it is a metal oxide such as aluminum oxide or an inorganic oxide such as silicon oxide which is a barrier layer on the lower surface of the intermediate layer It adheres firmly also to the vapor-deposited polyethylene terephthalate resin film (PET) surface on which is vapor-deposited.

  By using a linear low density polyethylene resin (LLDPE) polymerized with a single-site catalyst in the intermediate layer, the adhesive strength with the polyethylene terephthalate resin film (PET) surface is increased, and at the same time the mechanical strength is also increased. Therefore, it is possible to reduce the cracks generated in the barrier layer where stress is concentrated, such as a bent portion, when the liquid paper container is formed.

  However, even when such a laminated material as described above is used, there remains a problem that cracks are generated in a barrier layer where stress is concentrated, such as a bent portion, when a paper container for liquid is formed.

With reference to the drawings, the problem of deterioration of the barrier property of the liquid paper container in the conventional process will be schematically described. An overview of an example of the paper container is shown in FIG. 5, and a development explanatory view of the blank is shown in FIG. FIG. 3 shows a cross-sectional explanatory view of a portion including the ruled line portion for folding the paper of the paper container of FIG. FIG. 4 is a cross-sectional explanatory view of the same portion as FIG. 3 before forming a folding ruled line. FIG. 3 shows a cross-section of an example thereof. Liquid paper using a laminate using a barrier film including an inorganic compound vapor-deposited layer The laminate that forms the container is composed of the following layers.

  From the surface side of the container, ink layer 6 / synthetic resin layer 2 / base paper 1 / thermoplastic resin layer 3 / barrier film (including inorganic compound vapor deposition layer 7) 4 / sealant 5. Further, the folding ruled line C is formed on a laminate having a cross section shown in FIG.

  A typical structure of this barrier film, that is, an inorganic compound vapor-deposited plastic film, is a polyethylene terephthalate film deposited with silicon oxide, aluminum, or aluminum oxide.

  In the conventional process, blanks are punched out and folding ruled lines are formed after forming the laminate of FIG. 4, and a sleeve is formed by bending with the ruled lines, and then a necessary portion is bonded to form a paper container. This order was common (Patent Document 3).

However, unlike an aluminum foil having a thickness of several μm or more and a spreadability, when a vapor deposition layer of an inorganic compound having a vapor deposition thickness of 100 nm or less and a low spreadability is used as a barrier layer, as shown in FIG. However, the vapor deposition layer 7 of the forming part of the folding ruled line is stretched to cause cracks. As a result, the barrier property of the cracked part is deteriorated, so that the barrier property of the paper container is deteriorated.
JP-A-7-223627 JP 2004-250025 A JP-A-2005-239230 JP 2005-47149 A

The present invention has been made in view of the problems of the related art, and a liquid paper container capable of preventing cracks in a barrier layer at a bent portion where stress is concentrated when a liquid paper container formed from a laminated material is formed. It is a problem to provide a manufacturing method thereof.

  The present invention has been made to solve the above-mentioned problems, and the invention of claim 1 is a liquid paper container using a laminate including a barrier film, and the laminate is used for folding a base paper. A method for producing a liquid paper container, characterized in that it is laminated with the barrier film after ruled line processing.

  The invention of claim 2 is characterized in that the barrier film is a stretched plastic film selected from at least a polyester film, a polyamide film, and a polypropylene film, and a silicon oxide, aluminum oxide, or aluminum vapor deposition layer is provided. Item 2. A method for producing a liquid paper container according to Item 1.

  The invention of claim 3 is a gas barrier wherein the barrier film further comprises, in addition to the vapor deposition layer, at least one of a water-soluble polymer, (a) one or more metal alkoxides and hydrolysates thereof, and (b) tin chloride. 3. The method for producing a liquid paper container according to claim 2, wherein the liquid paper container is made of a layer structure in which a conductive film layer is laminated.

  The invention according to claim 4 is the method for producing a liquid paper container according to claim 3, wherein the water-soluble polymer is polyvinyl alcohol.

  The invention according to claim 5 is the method for producing a liquid paper container according to claim 3 or 4, wherein the metal alkoxide is tetraethoxysilane, triisopropoxyaluminum, or a mixture thereof.

  The invention according to claim 6 is a liquid paper container manufactured by the manufacturing method according to any one of claims 1 to 5.

  According to the manufacturing method of the present invention, the bending ruled line of the liquid paper container is stretched by shaping rather than after lamination of the laminate, that is, after the base paper and the inorganic compound vapor deposition layer are integrated. Create a blank that can be folded without sacrificing the barrier property of the ruled line part by forming the layer containing the base paper that needs to be ruled before lamination with the inorganic compound vapor deposition layer that causes cracking succeeded in.

  In the liquid paper container of the present invention, which has been a problem in the paper container using a conventional inorganic compound vapor deposition film as a barrier layer, the barrier property by causing the inorganic compound vapor deposition layer to be stretched and cracked when forming the folded ruled line Can be prevented.

  By this, the high barrier property of the laminated body further improved by including an inorganic compound such as silicon or aluminum or its oxide in the layer structure in the stretched plastic film originally excellent in the barrier property in the thickness direction can be improved. A liquid paper container having a high barrier property at the time of use can be obtained without being hindered by the manufacturing process.

  In addition to the vapor deposition layer, the barrier film further comprises a gas barrier coating layer comprising a water-soluble polymer and at least one of (a) one or more metal alkoxides and hydrolysates thereof or (b) tin chloride. Even if cracks occur in the deposited layer, the deterioration of gas barrier properties is minimized by the constitution, the water-soluble polymer is polyvinyl alcohol, and the metal alkoxide is tetraethoxysilane, triisopropoxyaluminum or a mixture thereof. It is limited to the limit and realizes the long-term excellent content preservation of the liquid paper container.

An embodiment of the liquid paper container of the present invention will be described in detail below based on the drawings.
FIG. 1 is a partial cross-sectional explanatory view of the paper container of the present invention. FIG. 2 is a partial cross-sectional explanatory view for explaining the paper container manufacturing method of the present invention. FIG. 3 is a partial cross-sectional explanatory view of a paper container of a comparative example. FIG. 4 is a partial cross-sectional explanatory diagram for explaining a paper container manufacturing method of a comparative example. 5 and 6 are a schematic view of a typical paper container already described and an explanatory view of blanks. FIG. 7 is a partial cross-sectional explanatory diagram of an example of an inorganic compound vapor-deposited plastic film.

  The manufacturing process of a liquid paper container is typically the order of substrate preparation, printing, ruled line processing, punching, pasting, filling of contents, and sealing, but here, the parts necessary for understanding the present invention are mainly used. Explained.

  An example of the manufacturing process of the liquid paper container of the present invention is that the stretched plastic film 4 having the inorganic compound vapor-deposited layer 7 formed on the surface and the sealant 5 are laminated by a known method such as dry lamination or extruder lamination. Let it be the inner layer film A of a laminated body.

  In addition, an extruder process is performed on the surface of the base paper with a polyethylene resin, and a corona treatment is performed on the surface. While printing on the corona-treated surface, the outer layer sheet B is created by processing the ruled lines C according to the printed pattern.

  While the anchor film (not shown) for easy adhesion is applied to the inorganic compound vapor-deposited plastic film side of the inner layer film A, the cross-section is laminated with the base paper surface of the printed and ruled outer layer sheet B and the thermoplastic resin 3. A laminate as shown in FIG. 1 is prepared. In the next step, it is punched into a blank shape in accordance with the printed pattern, and further sleeve processing is performed by heat fusion to obtain the liquid paper container of the present invention.

  On the other hand, in the example of the conventional manufacturing process of the liquid paper container, the stretched plastic film 4 having the inorganic compound vapor-deposited layer 7 formed on the surface and the sealant 5 are laminated by a known method such as dry lamination or extruder lamination. The inner layer film of the laminate of the paper container. Also, an extruder process is performed on the surface of the base paper with a polyethylene resin, and a corona treatment is performed on the surface to create an outer layer sheet.

  While carrying out an anchor coat (not shown) for easy adhesion on the inorganic compound vapor-deposited plastic film side of the inner layer film, the laminate is laminated with the base paper surface of the outer layer sheet and the thermoplastic resin 3 so that the cross section is as shown in FIG. create. While printing on this corona-treated surface, a ruled line process according to the printed pattern is performed, a blanking process is performed, and a sleeve process is performed by heat fusion to obtain a liquid paper container.

  The thermoplastic resin used for the synthetic resin layer 2 of the laminate of the present invention is not particularly limited as long as it can be easily melt-extruded by an extrusion lamination (extrusion lamination) apparatus and has heat sealability.

  For example, low density polyethylene resin (LDPE), medium density polyethylene resin (MDPE), high density polyethylene resin (HDPE), polypropylene resin (PP), etc. can be used. (LDPE) or linear linear low density polyethylene resin (LLDPE) is preferred.

The synthetic resin layer 2 is formed by coating the surface of the base paper 1 with the above resin by a normal extrusion process. Moreover, in order to improve the adhesiveness of the ink at the time of printing, it is normal to perform printing after performing a corona treatment on the extruded surface.

  The thickness of the synthetic resin layer 2 is appropriately determined depending on the type of contents to be filled in the paper container, the internal volume, the storage period, the suitability of the filling and packaging machine, and the like, but in the range of 20 μm to 40 μm considering the laminate strength. preferable.

  The base paper 1 of the laminate of the present invention has a function of maintaining the shape of the container (container shape retention), and mechanical strength such as tensile strength and burst strength, which is a property required as a packaging material. Satisfactory (such as suitability for packaging machinery), merchantability (concealment, printability, etc.), economy (price, transportability, etc.), and safety and hygiene (non-toxicity, easy disposal, etc.) For example, there is no restriction on the type of paper, and normal kraft paper (bleached or unbleached) can be used.

  As a raw material of the base paper 1, for example, wood fiber (chemical pulp, mechanical pulp), waste paper pulp, or the like is used as necessary. Among the wood fibers, the chemical pulp includes kraft pulp using caustic soda and sodium sulfide during wood chip cooking, and sulfite pulp using sulfite and bisulfite. These pulps may be unbleached or bleached.

  As mechanical pulp, groundwood pulp (GP) obtained by grinding logs with a grinder, refiner groundwood pulp (RGP) obtained by grinding (refining) waste wood from a sawmill, refined wood chips Examples thereof include thermomechanical pulp (TMP) obtained by heating and refining treatment. In addition, as TMP, C-TMP which refines under pressure after chemically processing a wood chip | tip, BC-TMP etc. which performed the bleaching process etc. shall be included. Of these wood fiber pulps, pulp having a long fiber length obtained from coniferous trees such as pine, larch, cedar, fir and cypress is preferably used for improving the stretchability and strength of the paper sheet.

  Moreover, examples of the used paper pulp include corrugated used paper and used magazine paper, and in particular, used corrugated paper can improve the stretchability and strength of the paper sheet and is preferably used.

  As papermaking chemicals added to make the base paper used in the present invention, the same sizing agent, paper strength enhancer, yield improver, etc. as used in normal papermaking should be used as necessary. Can do. For example, an internal sizing agent such as an alkyl ketene dimer, styrene acrylic resin, or rosin is used as the sizing agent.

  Paper strength enhancers and yield improvers include polyacrylamide resins, polyamide epichlorohydrin resins, polyethyleneimine and derivatives thereof, polyethylene oxide, polyamines, polyamides, polyamide polyamines and derivatives thereof, cationic and amphoteric starch, oxidized starch, carboxy starch, carboxy An organic compound such as methylated starch, plant gum, and polyvinyl alcohol, and an inorganic compound such as sulfate band, alumina sol, colloidal silica, and bentonite can be used in appropriate combination.

  Moreover, a filler can be added at the time of papermaking. As fillers, mineral fillers such as talc, kaolin, calcined kaolin, clay, diatomaceous earth, heavy calcium carbonate, magnesium carbonate, aluminum hydroxide, titanium dioxide, magnesium sulfate, silica, aluminosilicate, bentonite, polystyrene particles, Organic synthetic fillers such as urea formalin resin particles can be appropriately selected and used. Moreover, you may use these in combination arbitrarily.

Furthermore, additive agents for papermaking such as dyes, pH adjusters, slime control agents, antifoaming agents, and stickers can be appropriately used depending on the application. The pH at the time of papermaking according to the present invention can be arbitrarily selected between about 4.5, which is acidic papermaking, and about 6-8, which is neutral papermaking.

The thickness of the base paper 1 is appropriately determined depending on the type of contents to be filled in the paper container, the internal volume, the storage period, the suitability of the filling and packaging machine, etc., but the processing suitability (stiffness, bendability), etc. in the container molding process In consideration, the range of 200 g / m ² to 400 g / m ² is preferable.

  The printing ink for forming the ink layer 6 used in the present invention includes a colorant composed of a dye or pigment that gives color to the ink, and a resin that adheres to the substrate while dispersing and holding the colorant in fine particles. And a solvent that stably dissolves the resin, maintains the dispersibility of the pigment, maintains the fluidity of the ink, and transfers the appropriate amount of ink from the printing plate. Ordinary inks formed from auxiliary agents such as surfactants can be used for the purpose of improving properties, preventing precipitation, and improving fluidity.

  As the printing method of the ink layer 6, a known printing method such as a flexographic printing method, an offset printing method, or a gravure printing method can be used.

  Examples of the material of the thermoplastic resin layer 3 for bonding the inner layer film A and the base paper 1 of the laminate used in the present invention include ethylene-methacrylic acid copolymer, polyethylene resin, cyclic polyolefin resin, ionomer resin, polypropylene resin, and the like. Is mentioned. Particularly preferred is a linear low density polyethylene resin (LLDPE) polymerized with a single site catalyst.

  Linear low-density polyethylene resin polymerized with a single-site catalyst takes advantage of the characteristics of a single-site catalyst to provide higher strength, higher transparency, and lower temperature heat sealability than conventional linear low-density polyethylene resins. Have toughness. Vapor deposited polyethylene on which a metal oxide such as aluminum oxide or an inorganic oxide such as silicon oxide is deposited as a barrier layer on the lower surface of the thermoplastic resin layer 3 because of its excellent adhesion to a polyethylene terephthalate resin film (PET) It adheres firmly to the terephthalate resin film (PET) surface.

  By using a linear low density polyethylene resin (LLDPE) polymerized with a single-site catalyst for the thermoplastic resin layer 3, the adhesive strength with the polyethylene terephthalate resin film (PET) surface is increased, and at the same time mechanical strength Therefore, when the liquid paper container is formed, it is possible to prevent cracks generated in the barrier layer where stress is concentrated, such as a bent portion. The thickness of the thermoplastic resin layer 3 is preferably 15 μm to 50 μm. If the thickness is less than 15 μm, sufficient adhesive strength cannot be obtained, and if it is 51 m or more, it is not economical. In order to ensure sufficient adhesive strength between the inner layer film A and the base paper 1 used in the present invention, an anchor coat or a corona treatment may be performed on the inner layer film A side.

  As the barrier film 4 used in the present invention, a film obtained by evaporating at least an inorganic compound such as silicon oxide, aluminum or aluminum oxide on a stretched film (polyester, polyamide, polypropylene, etc.) is used.

  The deposited film thickness of the inorganic compound is preferably in the range of 5 to 300 nm, and the value is appropriately selected. However, if the film thickness is less than 5 nm, a uniform thin film may not be formed on the entire surface of the stretched film, and the gas barrier function may not be sufficiently achieved. On the other hand, when the film thickness exceeds 300 nm, the deposited film cannot be kept flexible, and the deposited film may be cracked due to external factors such as bending and pulling after the deposition.

The lamination method of the inorganic compound vapor deposition layer 7 can be formed by a normal vacuum vapor deposition method, and the heating means of the vacuum vapor deposition apparatus by the vacuum vapor deposition method is preferably an electron beam heating method, a resistance heating method, an induction heating method, In order to improve the adhesion to the biaxially stretched plastic film, a plasma assist method or an ion beam assist method can be used. Further, in order to increase the transparency of the deposited thin film layer 7, it is possible to carry out reactive deposition such as blowing oxygen gas at the time of deposition.

  A layer structure of a barrier film obtained by further laminating a gas barrier coating layer in addition to the inorganic compound vapor deposition layer is effective for further enhancing the effect of the present invention. The gas barrier coating layer will be described with reference to FIG.

  The gas barrier coating layer 34 is laminated to provide higher gas barrier properties and to protect the inorganic compound vapor deposition layer 7, and includes a water-soluble polymer, (a) one or more metal alkoxides, and hydrolysis. And (b) an aqueous solution containing at least one of tin chloride or a water / alcohol mixed solution is applied to form a coating agent. Evaporation of inorganic compounds using a solution in which water-soluble polymer and tin chloride are dissolved in an aqueous (water or water / alcohol mixed) solvent, or a solution in which metal alkoxide is directly or previously hydrolyzed is mixed. The layer 7 is formed by coating and heating and drying.

  Examples of the water-soluble polymer used in the gas barrier coating layer 34 include polyvinyl alcohol, polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, and sodium alginate. In particular, when polyvinyl alcohol (hereinafter referred to as PVA) is used, gas barrier properties are most excellent. PVA as used herein is generally obtained by saponifying polyvinyl acetate, from a so-called partially saponified PVA in which several tens percent of acetic acid groups remain to completely saponified PVA in which only several percent of acetic acid groups remain. Including, but not limited to.

The tin chloride may be stannous chloride (SnCl ₂ ), stannic chloride (SnCl ₄ ), or a mixture thereof, and may be an anhydride or a hydrate. Further, the metal alkoxide is preferably tetraethoxysilane, triisopropoxyaluminum or a mixture thereof.

As the method for laminating the gas barrier coating layer 34, known means such as a dipping method, a roll coating method, a screen printing method, a spray method and the like that are usually used can be used. The film thickness after drying may be 0.01 μm or more, but if the thickness exceeds 50 μm, cracks are likely to occur in the film, so the range of 0.01 to 50 μm is preferable. Further, the oxygen barrier property of the barrier film is preferably 20 ml / m ² · day · MPa or less in terms of permeability, and the water vapor barrier property is preferably ² g / m ² · day or less in terms of permeability.

  The sealant layer 5 used in the present invention is a low density polyethylene resin, a medium density polyethylene resin, a high density polyethylene resin, a polypropylene resin, an ionomer resin, an ethylene-vinyl acetate copolymer resin, an ethylene-vinyl acetate alcohol copolymer resin, A polyester resin, a polylactic acid resin, or the like can be used, but a linear low density polyethylene resin is preferable in consideration of heat sealability and economy.

  The thickness of the sealant layer 5 is appropriately determined depending on the type of contents to be filled in the liquid paper container, the internal volume, the storage period, the suitability of the filling and packaging machine, etc., but the range of 40 μm to 70 μm is considered in consideration of the heat seal strength. preferable.

The method of laminating the sealant layer 5 with a stretched plastic film selected from a polyester film, a polyamide film, and a polypropylene film, which is a support for the inorganic compound vapor deposition layer 7 used in the present invention, is a known dry lamination adhesive. The general dry lamination method used can be used.

  As the adhesive for dry lamination, urethane, modified butadiene, alkyl titanate, etc. can be used. However, since adhesiveness, cold resistance, flexibility, etc. are required, urethane is preferred, and the adhesive is promoted if necessary. An agent is added and used.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional explanatory view of the paper container of the present invention. FIG. 2 is a partial cross-sectional explanatory view for explaining the paper container manufacturing method of the present invention. FIG. 3 is a partial cross-sectional explanatory view of a paper container of a comparative example. FIG. 4 is a partial cross-sectional explanatory diagram for explaining a paper container manufacturing method of a comparative example.

<Example 1>
An inner layer film A of a laminate of a liquid paper container was prepared by laminating a 12 μm-thick silicon oxide vapor-deposited stretched polyester (PET) film and a 60 μm-thick linear low density polyethylene (LLDPE) film with an adhesive for dry lamination. .

Extruder processing of extrusion-type low-density polyethylene (LDPE) resin with a thickness of 20 μm is performed on the surface of SIE base paper (made by Oji Specialty Paper) with a basis weight of 400 g / m ² , and the LDPE side surface is subjected to corona treatment. Do. While printing on the corona-treated surface, a folding ruled line with a height of 200 μm matched to the printed pattern was processed to produce an outer layer sheet B.

  While performing a polyethyleneimine-based anchor coating for easy adhesion on the barrier film side of the inner layer film A, the base paper surface of the printed and ruled outer layer sheet B and a 30 μm thick ethylene-methacrylic acid copolymer (EMAA) Was laminated to prepare a laminate as shown in FIG.

  In the next step, blanks were punched in accordance with the printed pattern, and sleeve processing was further performed by heat fusion to obtain a liquid paper container of an example of the present invention.

<Comparative Example 1>
A 12 μm-thick silicon oxide vapor-deposited stretched polyester (PET) film and a 60 μm-thick linear low density polyethylene (LLDPE) film were laminated with an adhesive for dry laminating to prepare an inner layer film of a laminate of liquid paper containers.

Extruder processing of extrusion-type low-density polyethylene (LDPE) resin with a thickness of 20 μm is performed on the surface of SIE base paper (made by Oji Specialty Paper) with a basis weight of 400 g / m ² , and the LDPE side surface is subjected to corona treatment. An outer layer sheet was prepared.

  The inner layer film was laminated with a base paper surface of the outer layer sheet with an ethylene-methacrylic acid copolymer (EMAA) having a thickness of 30 μm while performing a polyethyleneimine anchor coating for easy adhesion on the barrier film side of the inner layer film. A laminated body showing a part of the cross section was prepared. While printing on this corona-treated surface, 200 μm high ruled line processing is performed according to the printed pattern, and in the next process, blanking is performed according to the printed pattern, and further, sleeve processing is performed by heat fusion, A liquid paper container of a comparative example was obtained.

<Comparison result>
About the liquid paper container of an Example and a comparative example, it measured about the characteristic of the following items. The results are shown in Table 1.
(1) Score ratio A value indicating the ratio of bending load obtained by bending a 90 ° folded blank line such as a ruled line when a load for folding a blank without a ruled line is 90 °.
(2) Barrier property without ruled line (oxygen)
A value measured by a measuring method defined in JIS K7126 after selecting a portion having no ruled lines from the sleeve and peeling off the laminate composed of only the barrier vapor deposited film and the sealant.
(3) Barrier property without ruled line (water vapor)
A value measured by a measuring method specified in JIS K7129 after selecting a portion having no ruled line from the sleeve and peeling off the laminate composed only of the barrier vapor deposited film and the sealant.
(4) Container barrier properties (oxygen, water vapor)
The sleeve is blank-molded into a 85 mm square 2 L size unplugged pack, and the oxygen transmission rate is measured at 20 ° C. and 60% RH using MOCON OX-TRAN 2/61.
(5) Container barrier properties (oxygen, water vapor)
The sleeve was molded by putting 50 g of calcium chloride into a 85 mm square 2 L size non-plugged pack, stored in a constant temperature and humidity chamber at 40 ° C. and 90% RH, and the water vapor permeability was measured.

以下に実施例と比較例の比較結果について説明する。

Below, the comparison result of an Example and a comparative example is demonstrated.

<Comparison result>
In the liquid paper container manufactured by the method of Example 1 of the present invention, the ratio of the bending load of the ruled line portion to the bending load of the other portions, that is, the score ratio is 0.4 to 0.6, which is manufactured by the conventional method. The score ratio of the liquid paper container of Comparative Example 1 was not changed. This means that the ease of folding of the ruled line portion does not change depending on the difference in the order of forming the bent ruled lines.

As a result of peeling off only the vapor-deposited film and the sealant layer in the portion without the folding ruled line of the liquid paper container manufactured by the method of Example 1 of the present invention, the oxygen permeability and the water vapor permeability were measured. The oxygen permeability was 10 ml / m ² · day · MPa, and the water vapor permeability was 1.0 g / m ² · day compared to the results measured in the same manner from the liquid paper container. This means that if the configuration of the laminate used in the liquid paper container is the same and the state of each layer is the same, the barrier property of the laminate is not different depending on the difference in the manufacturing process between Example 1 and Comparative Example 1. It shows no.

  Regarding the barrier property of the liquid paper container in the state molded into the container, a clear difference was observed between the case of being manufactured by the method of Example 1 of the present invention and the case of being manufactured by the method of Comparative Example 1. In Comparative Example 1, the oxygen permeability is 0.2 ml / pack · day · 0.2 atm, which is about 4 times the 0.05 ml / pack · day · 0.2 atm in Example 1, and the water vapor permeability is also In the case of Comparative Example 1, 0.4 g / pack · day is about four times as large as 0.1 g / pack · day in Example 1.

  Since there is no difference in the constituent materials of the laminates of Example 1 and Comparative Example 1, considering the difference in the manufacturing process, the difference in the barrier property of the liquid paper container in the state molded into the container is the ruled line to the laminate This is considered to be caused by the difference in the forming of the film, that is, the presence or absence of the forming of the bent ruled line on the inorganic compound deposited layer.

  From the above, the liquid paper container manufactured by the method of Example 1 of the present invention is devised in the forming order of the folding ruled lines so that the barrier property of the bent part does not deteriorate, so that We have succeeded in making the most of the barrier properties we have. As a result, we were able to establish a technology that can improve the content protection of liquid paper containers and contribute to the expansion of applications.

Partial cross-sectional explanatory drawing of the paper container of the present invention Partial sectional explanatory drawing of the paper container manufacturing method of the present invention Partial sectional view of a conventional paper container Partial cross-sectional explanatory diagram of a conventional paper container manufacturing method An example of an outline drawing of a paper container Explanatory drawing of an example of paper container blanks Partial cross-sectional explanatory diagram of an example of an inorganic compound vapor deposition film

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base paper 2 ... Synthetic resin layer 3 ... Thermoplastic resin layer 4 ... Barrier film 5 ... Sealant 6 ... Ink layer 7 ... Inorganic compound vapor deposition layer 20 ... Base film 30 ... Barrier film 32 ... Deposition anchor layer 33 ... Inorganic compound vapor deposition Layer 34 ... Gas barrier coating layer A ... Inner layer film B ... Outer layer sheet C ... Bending ruled line

Claims (6)

  A liquid paper container using a laminated body including a barrier film, wherein the laminated body is obtained by laminating the base paper after the folding ruled line is processed on the base paper. .   The liquid paper according to claim 1, wherein the barrier film is a stretched plastic film selected from a polyester film, a polyamide film, and a polypropylene film, and at least a deposited layer of silicon oxide, aluminum oxide, or aluminum is provided. Container manufacturing method.   In addition to the vapor deposition layer, the barrier film further comprises a gas barrier coating layer comprising a water-soluble polymer and at least one of (a) one or more metal alkoxides and hydrolysates thereof or (b) tin chloride. The method for producing a liquid paper container according to claim 2, comprising a configuration.   The method for producing a liquid paper container according to claim 3, wherein the water-soluble polymer is polyvinyl alcohol.   4. The method for producing a liquid paper container according to claim 3, wherein the metal alkoxide is tetraethoxysilane, triisopropoxyaluminum, or a mixture thereof.   A liquid paper container manufactured by the manufacturing method according to any one of claims 1 to 5.

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