JP2010089821A - Paper container for liquid - Google Patents

Abstract

The present invention provides a liquid paper container capable of preventing cracking of a barrier layer in a bent portion where stress is concentrated during molding of a liquid paper container formed from a laminated material using a metal or inorganic compound vapor-deposited film as a barrier film. thing.
A liquid paper container using a laminate including a barrier film on which a metal or an inorganic compound is vapor-deposited, wherein the inorganic compound vapor-deposited layer is laminated between stretched plastic films. container.
[Selection] Figure 1

Description

  The present invention relates to a paper container used to store liquids such as beverages, seasonings, detergents, pharmaceuticals, and industrial chemicals, and more particularly to a liquid paper container having a high barrier property using a metal or 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 characteristics 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 containers to prevent the seepage 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. Also, the use of metal foil has a problem that it makes it difficult to use a metal detector used for inspection of internal foreign matter.

  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 to maintain the quality preservation of the contents was conventionally laminated with a material with high barrier properties 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. ) By increasing the thickness, and so on.

  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 barrier properties of a conventional liquid paper container 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 part as FIG. 3 before forming a ruled line for bending. FIG. 3 shows a cross section of the example, and a laminate using a barrier film including a metal or inorganic compound vapor-deposited layer is used. The laminate forming the liquid paper container is composed of the following layers.

  From the surface side of the container, ink layer (6) / thermoplastic 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, a metal or inorganic compound vapor-deposited plastic film, is a polyethylene terephthalate film deposited with silicon oxide, aluminum or aluminum oxide.

  In the conventional liquid paper container, blanks are punched and folding ruled lines are formed after forming the laminate shown in FIG. 4. The order of forming 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, and as a result, the barrier property of the cracked part is lowered, so that the barrier property of the paper container is deteriorated. It was.
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.

  The present invention has been made to solve the above-mentioned problems, and the invention of claim 1 is directed to a barrier film having a vapor-deposited layer on which a metal or an inorganic compound is vapor-deposited, and a stretched plastic on the vapor-deposited layer of the barrier film. A liquid paper container characterized by being laminated by laminating films.

  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 vapor deposition layer selected from silicon oxide, aluminum oxide, or aluminum is provided. The liquid paper container according to claim 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. The liquid paper container according to claim 2, wherein the liquid paper container comprises a layered structure in which a conductive coating layer is laminated.

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

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

  A sixth aspect of the present invention is the liquid paper container according to any one of the first to fifth aspects, wherein a ruled line for molding is provided.

  According to the present invention, the local elongation of the metal or inorganic compound vapor deposition layer at the time of forming or folding the folding ruled line of the blank of the liquid paper container is suppressed by the stretched plastic film in close contact with both surfaces of the vapor deposition layer, It was made possible to create a blank that can be folded without sacrificing the barrier property of the ruled line portion by preventing cracks in the metal or inorganic compound vapor deposition layer that are generated by stretching or bending.

  The laminate of the liquid paper container whose cross section is shown in FIG. 4 is schematically shown in FIG. 3 as the inorganic compound vapor deposition layer (7) is deformed by pressure by forming a ruled line at the position C. Such cracks are generated. As a result, the barrier property of the bent portion is lowered.

  On the other hand, in the liquid paper container of the present invention, the inorganic compound vapor-deposited layer is stretched at the time of forming the folded ruled line, which has been a problem in the paper container using the conventional inorganic compound vapor-deposited film as the barrier layer, and cracks are generated. Deterioration of the barrier property due to the occurrence can be prevented.

The laminated body of the liquid paper container of the present invention whose cross section is shown in FIG. 2 is sandwiched between the inorganic compound vapor-deposited layer (7) and the stretched plastic film (8) and the stretched plastic film (4). Therefore, even when the ruled line is formed at the position C, the deformation due to the pressure of the inorganic compound vapor deposition layer (7) is suppressed, and as shown schematically in FIG. The decrease in barrier properties can be minimized.

  As a result, the barrier property of the laminate, which has been further improved by including a metal or inorganic compound such as silicon or aluminum in a layered structure in a stretched plastic film that originally has an excellent barrier property in the thickness direction, is a manufacturing process of a liquid paper container. A liquid paper container having a high barrier property during use can be obtained without being hindered.

  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. These effects are particularly prominent when a ruled line for molding is included, because the ruled line or the bent portion is prevented from being lowered by a barrier.

  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 a liquid paper container of the present invention. FIG. 2 is a partial cross-sectional explanatory diagram for explaining a method for manufacturing a liquid paper container of the present invention. FIG. 3 is a partial cross-sectional explanatory view of a liquid paper container of a comparative example. FIG. 4 is a partial cross-sectional explanatory diagram for explaining a method of manufacturing a liquid paper container of a comparative example. FIG. 5 and FIG. 6 are a schematic view of a typical liquid 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.

  When showing an example of the manufacturing process of the liquid paper container of the present invention, the inorganic compound deposition layer side of the stretched plastic film (4) having the inorganic compound deposition layer (7) formed on the surface and the stretched plastic film (8) are laminated, Further, a sealant (5) is laminated to form an inner layer film of a laminate of liquid paper containers. This laminating can be performed by a known method such as dry laminating or extruder laminating.

  Moreover, an extruder process is performed on the surface of the base paper (1) with a polyethylene resin (2), and a corona treatment is performed on the surface to create an outer layer sheet.

  While performing an anchor coat (not shown) for easy adhesion on the surface opposite to the sealant (5) of the inner layer film, the outer layer sheet is laminated with the thermoplastic resin (3). Printing is performed on the corona-treated surface to form a laminate having a cross section as shown in FIG. Thereafter, ruled line processing according to the printed pattern is performed, punched into blanks, 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 manufacturing process of the conventional liquid paper container, a well-known stretched plastic film (4) having an inorganic compound vapor deposition layer (7) formed on the surface and a sealant (5) such as dry lamination or extruder lamination are known. Lamination is performed to form an inner layer film of a laminate of liquid paper containers. Moreover, an extruder process is performed on the surface of the base paper (1) with a polyethylene resin (2), and a corona treatment is performed on the surface to create an outer layer sheet.

  This corona-treated surface is laminated with the base paper surface of the outer layer sheet and the thermoplastic resin (3) while performing an anchor coating (not shown) for easy adhesion on the metal or inorganic compound vapor-deposited plastic film side surface of the inner layer film. 4 is printed to create a laminate having a cross section as shown in FIG. After this, ruled line processing according to the printed pattern is performed, punched into blanks, and sleeve processing is performed by heat fusion to obtain a liquid paper container.

  The thermoplastic resin used in the thermoplastic resin layer (2) of the liquid paper container of the present invention is limited in its kind as long as it can be easily melt-extruded by an extrusion lamination (extrusion lamination) apparatus and has heat sealability. is not.

  For example, low density polyethylene resin (LDPE), medium density polyethylene resin (MDPE), high density polyethylene resin (HDPE), polypropylene resin (PP), cyclic olefin polymer, PET-G, ethylene vinyl alcohol copolymer, etc. may be used. However, in consideration of heat sealability, low density polyethylene resin (LDPE) or linear linear low density polyethylene resin (LLDPE) is preferable.

  The thermoplastic resin layer (2) is formed by coating the above resin on the surface of the base paper (1) 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 thermoplastic 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, etc., but considering the laminate strength, the thickness is 5 to 30 μm. The range of is preferable.

  The base paper (1) of the liquid paper container according to the present invention has a function of maintaining the shape of the container (container shape retention), and also has protective properties (tensile strength, burst strength, etc.) required for packaging materials. Mechanical strength), workability (packaging machine suitability, etc.), merchantability (concealment, printing suitability, etc.), economy (price, transportability, etc.), safety and hygiene (non-toxic, easy disposal, etc.) If satisfied, the type of paper is not particularly limited, and ordinary 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 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 according to 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 suitability for processing in the container molding process (stiffness, bendability) ) Etc., the basis weight is preferably in the range of 200 g / m ² to 600 g / m ² .

  The printing ink for forming the ink layer (6) used in the liquid paper container of the present invention comprises a color material composed of a dye or a pigment that imparts color to the ink and a coating material while dispersing and holding the color material in fine particles. A vehicle composed of a resin to be fixed to a printing body, a solvent that stably dissolves the resin, maintains dispersibility of pigment, fluidity of ink, and can transfer an appropriate amount of ink from a printing plate, and further color For the purpose of improving the dispersibility of the material, color development, prevention of precipitation, and improvement of fluidity, ordinary inks formed from auxiliary agents such as surfactants can be used.

  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 and the base paper (1) used in the liquid paper container of the present invention include ethylene-methacrylic acid copolymer (EMMA), ethylene-acrylic acid copolymer Examples include coalescence (EAA), ionomer resin, low density polyethylene resin (LDPE), medium density polyethylene resin (MDPE), high density polyethylene resin (HDPE), cyclic polyolefin resin, and polypropylene resin. 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. Since the adhesiveness with the polyethylene terephthalate resin film (PET) is excellent, a metal oxide such as aluminum oxide or an inorganic oxide such as silicon oxide is deposited on the lower surface of the thermoplastic resin layer (3). When the film is a polyethylene terephthalate resin film (PET), it adheres particularly firmly.

  By using a linear low-density polyethylene resin (LLDPE) polymerized with a single-site catalyst in the thermoplastic resin layer (3), the adhesive strength with the polyethylene terephthalate resin film (PET) surface is increased and at the same time mechanical Since the mechanical strength is also increased, the effect of preventing cracks occurring in the barrier layer where stress is concentrated, such as a bent portion, when the liquid paper container is molded can be further enhanced. The thickness of the thermoplastic resin layer (3) is preferably 10 μm to 60 μm. If the thickness is less than 10 μm, sufficient adhesive strength cannot be obtained, and if it is 60 μm or more, it is not economical. In order to ensure sufficient adhesive strength between the inner layer film used in the present invention and the base paper (1), anchor coating or corona treatment may be performed on the inner layer film side.

  The barrier film (4) used in the present invention is a stretched film (polyester, polyamide, polypropylene, etc.) obtained by vapor-depositing at least a metal such as silicon oxide, aluminum or aluminum oxide or an inorganic compound. The thickness of the barrier film (4) is preferably in the range of 6 μm to 30 μm.

  The deposited film thickness of the metal or 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, flexibility cannot be maintained in the vapor deposition film, and it is not desirable because the vapor deposition film may be cracked due to external factors such as bending and pulling after the film formation.

  The lamination method of the inorganic compound vapor deposition layer (7) can be formed by a normal vacuum vapor deposition method. As a heating means of the vacuum vapor deposition apparatus by the vacuum vapor deposition method, there are an electron beam heating method, a resistance heating method, an induction heating method, and the like. Preferably, a plasma assist method or an ion beam assist method can be used to improve the adhesion to the biaxially stretched plastic film. Moreover, in order to raise the transparency of an inorganic compound vapor deposition layer (7), even if it carries out the reactive vapor deposition which blows in oxygen gas etc. in the case of vapor deposition, it does not care.

  A layer configuration of a barrier film obtained by further laminating a gas barrier coating layer in addition to a metal or inorganic compound deposition layer is effective for further enhancing the effects of the present invention. This 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 and (a) one or more metals. It is formed by applying a coating agent mainly composed of an aqueous solution containing at least one of alkoxide and hydrolyzate or (b) tin chloride, or a water / alcohol mixed solution. 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. It is formed by coating and heating and drying on the layer (7).

  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 commonly used dipping method, roll coating method, screen printing method, spray method and the like 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. The barrier film preferably has an oxygen barrier property of 20 ml / m ² · day · MPa or less in terms of permeability and a water vapor barrier property of 2 g / m ² · day or less in terms of permeability.

  The stretched film (8) used in the present invention is a stretched film such as polyester, polyamide, or polypropylene. The stretched film (8) preferably has a thickness in the range of 6 μm to 30 μm.

  The sealant (5) used in the present invention is a low density polyethylene resin, medium density polyethylene resin, high density polyethylene resin, polypropylene resin, ionomer resin, ethylene-vinyl acetate copolymer resin, ethylene-vinyl acetate alcohol copolymer resin. Polyester resin, polylactic acid resin, and 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 (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 in the range of 30 μm to 90 μm considering the heat seal strength. Is preferred.

  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 as a support for the barrier film (4) used in the present invention is a known dry lamination adhesive. The general dry lamination method used can be used. The same applies when the stretched plastic film (8) laminated on the inorganic compound vapor deposition layer side of the barrier film (4) and the sealant layer (5) are laminated.

  In the liquid paper container of the present invention, the stretched plastic film (8) needs to be laminated on the surface of the barrier film (4) on the inorganic compound vapor deposition layer (7) side. As in 2, the stretched plastic film (8) and the barrier film (4) may be laminated from the sealant (5) side, and the barrier film (4) and the stretched plastic film (8) from the sealant (5) side. The order in which the layers are stacked may 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>
Laminate a 12 μm thick stretched polyester (PET) film with an aluminum oxide deposited surface and a 12 μm thick stretched polyester (PET) film by laminating with an adhesive for polyurethane dry laminating (application amount 3 g / m ² ). A film was created.

The laminated film and a linear low-density polyethylene (LLDPE) film having a thickness of 60 μm were laminated with a polyurethane-based dry laminating adhesive (amount applied: 3 g / m ² ) to form a laminated body serving as an inner layer of a liquid paper container.

Moreover, the barrier of the laminated body which becomes the said inner layer by extruding ethylene-methacrylic acid copolymer (EMMA) resin by the thickness of 40 micrometers on the surface of SIE base paper (1) (made by Oji Specialty Paper) with a basic weight of 400 g / m < ² >. Extruder lamination with the film surface (4) was performed. Further, an LDPE resin having a thickness of 15 μm was laminated on the paper surface, and a corona treatment was performed in-line on the LDPE side surface, so that a laminate having a part of the cross section shown in FIG. 2 was produced. The sheet was cut to a predetermined size while performing gravure printing on the corona-treated surface. Blanks were created on the cut sheet by performing punching and ruled line matching with the printed pattern. Furthermore, sleeve processing was performed by heat fusion to obtain a liquid paper container.

<Comparative Example 1>
An aluminum oxide vapor-deposited surface of a 12 μm thick aluminum oxide-deposited stretched polyester (PET) film and a polyethylene (PE) film having a thickness of 40 μm are extruded with a low-density polyethylene resin having a thickness of 20 μm to form an inner layer of a liquid paper container. A laminate was created.

Moreover, the barrier of the laminated body which becomes the said inner layer by extruding ethylene-methacrylic acid copolymer (EMMA) resin by the thickness of 40 micrometers on the surface of SIE base paper (1) (made by Oji Specialty Paper) with a basic weight of 400 g / m < ² >. Extruder lamination with the film surface (4) was performed. Further, an LDPE resin having a thickness of 15 μm was laminated on the paper surface, and a corona treatment was performed in-line on the LDPE side surface, so that a laminate having a part of the cross section shown in FIG. 2 was produced. The sheet was cut to a predetermined size while performing gravure printing on the corona-treated surface. Blanks were created on the cut sheet by performing punching and ruled line matching with the printed pattern. Furthermore, sleeve processing was performed by heat fusion to obtain a liquid paper container.

<Comparison result>
For the liquid paper containers of Examples and Comparative Examples, packs were prepared from each sleeve, and the characteristics of the following items were measured. The results are shown in Table 1.
(1) Oxygen permeability OX-TRAN 2/61 manufactured by MOCON was measured under the conditions of 20 ° C. and 60% RH. (2) Water vapor permeability Value measured by the measuring method defined in JIS Z0222.

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>
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 0.14 ml / pack · day · 0.2 atm, which is larger than 0.09 ml / pack · day · 0.2 atm in Example 1, and the water vapor permeability is also a comparative example. 0.15 g / pack · day in the case of 1 is larger than 0.10 g / pack · day in the first embodiment.

From the above, the liquid paper container produced by the method of Example 1 of the present invention is obtained by closely reinforcing the stretched plastic film so that the inorganic compound vapor deposition layer coating of the ruled line processed portion and the bent portion does not break, The barrier property of the metal or inorganic compound deposition layer could be utilized to the maximum. 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 ... Thermoplastic resin layer 3 ... Thermoplastic resin layer 4 ... Barrier film 5 ... Sealant 6 ... Ink layer 7 ... Inorganic compound vapor deposition layer 8 ... Stretched plastic film 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 comprising a barrier film having a vapor deposition layer on which a metal or an inorganic compound is vapor-deposited, and a laminate of a stretched plastic film laminated on the vapor deposition layer of the barrier film.   The barrier film is a stretched plastic film selected from a polyester film, a polyamide film, and a polypropylene film, and is provided with at least a vapor deposition layer selected from silicon oxide, aluminum oxide, or aluminum. Liquid paper container.   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 liquid paper container according to claim 2, comprising a configuration.   The liquid paper container according to claim 3, wherein the water-soluble polymer is polyvinyl alcohol.   4. The liquid paper container according to claim 3, wherein the metal alkoxide is tetraethoxysilane, triisopropoxyaluminum, or a mixture thereof.   6. The liquid paper container according to claim 1, further comprising a ruled line for molding.

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