JP2006297604A - Packaging raw paper, and paper container or cup for liquid using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide packaging raw paper not causing a foaming phenomenon (a phenomenon that layers are peeled to float) due to steam even if steam is formed in the packaging raw paper by hot air at the time of molding when a paper container or cup for a liquid is molded, and the paper container or cup for the liquid using it. <P>SOLUTION: A thermoplastic resin layer (4) is provided on the non-contact surface with a resin layer (1b) of one paper layer (a) of multilayered paper (1) constituted by laminating paper layers (1a) and (1c) through a linearly extruded resin layer (1b), and at least a barrier layer (2) and a sealant layer (3) are successively laminated on the non-contact surface with the resin layer (1b) of the other paper layer (1c) to obtain the packaging raw paper. The paper container or cup for the liquid using it is also disclosed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a packaging paper used for liquid paper containers or cups for storing liquids such as sake, shochu, wine, fruit juice beverages, and more particularly, when molding liquid paper containers or cups, The present invention relates to a packaging base paper and a liquid paper container or cup using the same, in which even if water vapor is generated in the packaging base paper by hot air, the foaming phenomenon due to the water vapor (a phenomenon in which the interlayer peels off and rises) does not occur.

  Conventionally, liquid paper containers for storing liquids such as sake, shochu, wine, and fruit juice drinks are gable roof, brick, cylindrical liquid paper containers, or liquid paper with an inner seal lid for personal use. For cups and the like, the layer structure of the material used is usually a laminate structure composed of a thermoplastic resin layer / paper layer / thermoplastic resin layer / barrier layer / sealant layer because it is mainly used for long-term room temperature circulation. .

  For example, low density polyethylene (LDPE) layer / paper layer / low density polyethylene (LDPE) layer / inorganic compound deposited film layer / low density polyethylene (LDPE) layer configuration, or low density polyethylene (LDPE) layer / paper layer / acid Laminate materials (hereinafter referred to as packaging base paper) such as a copolymer adhesive resin layer / inorganic compound vapor-deposited film layer / low density polyethylene (LDPE) layer structure are used.

  For example, in the case of a gable roof-shaped liquid paper container, a blank is produced by punching the above-described packaging base paper, and a sleeve is produced by side-pasting this blank with a special sack pasting machine (frame sealer). This sleeve is loaded into a liquid filling and molding machine, and a liquid paper container filled with contents is produced by box-making, filling and sealing.

  By the way, when a liquid paper container or cup is formed using the packaging base paper as described above, a method of melting and molding / pressing the thermoplastic resin forming the outermost layer and the innermost layer of the packaging base paper with hot air Is taken. Due to the heat of hot air at the time of molding, the moisture in the paper layer that forms the packaging base paper is generated as water vapor, and this water vapor causes the inorganic compound vapor deposition film layer to float (foam) from the paper layer. To do. When such a phenomenon occurs, the deposited film is torn during subsequent molding, and problems such as pinholes are likely to occur.

  Therefore, by extruding and laminating a paper layer and an inorganic compound vapor-deposited film layer with a low-density polyethylene resin, processing while applying ozone treatment increases the adhesive strength between the inorganic compound vapor-deposited film layer and the low-density polyethylene resin layer. There is a proposal for making foaming difficult (see, for example, Patent Document 1). However, in this case, since the water vapor generated from the paper layer cannot be prevented, a great effect cannot be obtained.

  There is also a method of dry laminating the paper layer and the inorganic compound vapor deposited film layer with an adhesive, but in this case, an adhesive that can withstand high temperatures is used, so even if water vapor is generated, foaming phenomenon However, as compared with extrusion lamination, the number of processes is likely to increase, the processing speed is slow, aging time is required, and the processing unit cost is high.

Prior art documents are shown below.
JP 2002-144467 A

  The present invention is intended to solve such problems of the prior art, and even when liquid paper containers or cups are molded, even if water vapor is generated in the packaging base paper due to hot air during molding, the present invention It is an object of the present invention to provide a wrapping base paper that does not cause a foaming phenomenon caused by water vapor (a phenomenon in which the layers peel and rise) and a liquid paper container or cup using the same.

  The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 of the present invention includes a paper layer (1a) and a resin layer (1b) extruded in a linear manner. A thermoplastic resin layer (4) is provided on the surface of the multilayer paper (1), which is combined with the paper layer (1c), on the side not contacting the resin layer (1b) of one of the paper layers (1a), and A packaging base paper characterized in that at least a barrier layer (2) and a sealant layer (3) are sequentially laminated on the surface of the other paper layer (1c) that does not contact the resin layer (1b). is there.

  The invention according to claim 2 of the present invention is the packaging base paper according to claim 1, wherein the barrier layer (2) is a resin film having at least a deposited thin film layer made of an inorganic oxide. It is a base paper.

  The invention according to claim 3 of the present invention is the packaging base paper according to claim 2, wherein the inorganic oxide is made of aluminum oxide or silicon oxide.

  The invention according to claim 4 of the present invention is a liquid paper container using the packaging base paper according to any one of claims 1 to 3.

  The invention according to claim 5 of the present invention is a cup using the packaging base paper according to any one of claims 1 to 3.

  The packaging base paper of the present invention is a thermoplastic resin on the surface of the multilayer paper in which the paper layer and the paper layer are combined with each other through the resin layer extruded in a linear shape, and does not contact the resin layer of one of the paper layers. When forming a liquid paper container or cup by forming a resin layer and laminating at least a barrier layer and a sealant layer sequentially on the surface of the other paper layer that does not contact the resin layer. Even if water vapor is generated in the packaging base paper due to the hot air at the time, the foaming phenomenon due to the water vapor (a phenomenon in which the interlayer peels off and rises) does not occur.

  An embodiment of the present invention will be described in detail with reference to FIG.

  FIG. 1 is a side sectional view showing an embodiment of a layer structure of a packaging base paper (A) according to the present invention.

  As shown in FIG. 1, the packaging base paper (A) of the present invention is a multilayer paper in which a paper layer (1a) and a paper layer (1c) are interleaved via a resin layer (1b) extruded in a linear shape ( 1) a thermoplastic resin layer (4) is provided on the surface of one paper layer (1a) that does not contact the resin layer (1b), and the other paper layer (1c) is a resin layer. This is a packaging base paper in which at least a barrier layer (2) and a sealant layer (3) are sequentially laminated on the surface not in contact with (1b).

Next, the material which comprises the said packaging base paper (A), its lamination method, etc. are demonstrated in detail.

  The multilayer paper (1) is a base material for forming a container among the layer structure of the packaging base paper (A), and generally has formability, bending resistance, rigidity, waist, strength, and the like. Therefore, as the paper layers (1a, 1c) constituting the multilayer paper (1), for example, a strongly sized exposed or unexposed paper base material, or pure white roll paper, Paper base materials such as kraft paper, paperboard, and processed paper, and the like can be used as appropriate.

As the paper substrate for forming the paper layer (1a, 1c), it is preferable to select and use one having a basis weight in the range of about 80 to 600 g / m ² .

  Next, the multilayer paper (1) is bonded to the paper layer (1a) and the paper layer (1c) through a multi-row resin layer (1b) formed by linearly extruding the paper layer (1a) and the paper layer (1c) at an arbitrary width and an arbitrary interval. It is made by paper. Since the resin layer (1b) is formed at an arbitrary interval by extrusion lamination in a linear manner as described above, a space (S) is provided between the paper layer (1a) and the paper layer (1c). A multilayer paper (1) is obtained.

  By using the multilayer paper (1) obtained in this way, water (V) generated from paper heated by hot air (H) at the time of molding, such as a liquid paper container or cup, is generated in this space (S). It is possible to escape from.

  Next, the resin forming the resin layer (1b) is not particularly limited as long as it is melted by heat and is a thermoplastic resin having adhesiveness with the paper layers (1a, 1c). Density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer Polyolefin resins such as polymers, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, methylpentene polymer, polybutene polymer, polyethylene or polypropylene, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, Modified with unsaturated carboxylic acids such as itaconic acid Acid-modified polyolefin resin, polyvinyl acetate resin, poly (meth) acrylic resins, polyvinyl chloride resins, can be used resins such as other.

  Among these thermoplastic resins, it is appropriate to use low density polyethylene from the viewpoint of workability and economy, and the low density polyethylene or the like between the paper layer (1a) and the paper layer (1c). The thermoplastic resin is heated, melted in a cylinder called a cylinder, extruded by applying pressure with a screw, and the resin dissolved in a curtain shape is extruded from a thin slit called a T die at the tip of the cylinder. A sand lamination method using an extrusion lamination method (melt extrusion lamination method) in which the resin layer (1b) is sandwiched and laminated can be used.

  Moreover, the thickness of this resin layer (1b) can be arbitrarily selected and formed within the range of about 10-50 micrometers. In addition, as a method of interleaving the paper layer (1a) and the paper layer (1c), a lamination method using an adhesive is also possible. However, in consideration of productivity and cost, the above-mentioned extrusion lamination is used. It is preferable to form the resin layer (1b) by a sand lamination method using a method (melt extrusion lamination method).

Next, as the outermost thermoplastic resin layer (4) provided on the surface of the multilayer paper (1) not contacting the resin layer (1b) of one paper layer (1a), a container is manufactured. Since it is necessary to play the role of adhesiveness, a thermoplastic resin or a film thereof that can be melted by heat and fused to each other is used, and a resin that forms the resin layer (1b) described above Similar thermoplastic resins can be used. Also, the thickness can be arbitrarily selected and formed within a range of about 10 to 50 μm.

  As a lamination method, for example, an extrusion lamination method (melt extrusion lamination method) in which a thermoplastic resin such as the above-mentioned low-density polyethylene is directly extruded onto the paper layer (1a) for lamination is used, and a thermoplastic resin layer is used. (4) can be used, or a dry lamination method in which a thermoplastic resin film is laminated through a lamination adhesive layer (not shown) can be used.

  On the surface of the thermoplastic resin layer (4), the outermost layer, a printing ink layer (not shown) such as letters and pictures is used using a normal gravure ink, offset ink, flexographic ink, silk screen ink, etc. The gravure printing method, the offset printing method, the flexographic printing method, and the silk screen printing method can be used. At this time, the surface of the thermoplastic resin layer (4) is preferably subjected to a surface treatment such as a corona treatment or a gas flame treatment to achieve ink adhesion.

  Next, the barrier layer (2) provided below the other paper layer (1c) not contacting the resin layer (1b) is made of a gas barrier material, for example, an inorganic oxide vapor-deposited thin film layer ( (Not shown) resin film, aluminum vapor-deposited film, aluminum foil, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, ethylene-vinyl acetate copolymer saponified film, polyethylene terephthalate, polyamide, polyvinyl alcohol A film obtained by coating polyvinylidene chloride on a saponified ethylene-vinyl acetate copolymer or a laminated material combining one or more of these films can be used, but preferably has a good gas barrier property. Resin film with an inorganic oxide vapor-deposited thin film layer with excellent environmental adaptability Lum is preferable.

  As the vapor-deposited thin film layer of the inorganic oxide, any vapor-deposited thin film layer in which a metal oxide is made amorphous can be used. For example, silicon (Si), aluminum (Al), Magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), yttrium (Y), etc. It is possible to use a vapor-deposited thin film layer obtained by making the metal oxide amorphous.

  Among these metals, aluminum (Al) and silicon (Si) are preferable when used for packaging materials, and the oxides of these metals, such as aluminum oxide and silicon oxide, are deposited by vacuum deposition or the like. It is appropriate to do. The film thickness at that time is preferably in the range of 5 to 400 nm. If the film thickness is less than 5 nm, a uniform film cannot be provided, so that sufficient gas barrier properties cannot be obtained. If the film thickness exceeds 400 nm, flexibility is lost, and the evaporated thin film layer is caused by external factors such as bending and pulling. It is not preferable because cracks and peeling easily occur.

In addition, the resin film layer serving as a support for forming the vapor-deposited thin film layer of the inorganic oxide is particularly restricted as long as it is strong, strong in heat resistance, and chemically excellent. However, for example, polyolefin resin such as polyethylene, polypropylene, polybutene, (meth) acrylic resin, polyvinyl chloride resin, polystyrene resin, polyvinylidene chloride resin, saponified ethylene-vinyl acetate copolymer, Various resins such as polyvinyl alcohol, polycarbonate resin, fluorine resin, polyvinyl acetate resin, acetal resin, polyester resin, polyamide resin, etc. can be used, but strength, heat resistance, etc. Considering physical properties, processability, economics such as cost, etc. Film is preferred. It is preferable that the thickness of the resin film is arbitrarily selected and used within a range of about 10 to 40 μm.

  Next, as a method of forming the inorganic oxide vapor-deposited thin film layer on the resin film layer as the support described above, a vacuum vapor deposition method, a sputtering method, or the like can be used. Vapor deposition is preferred.

  There are three types of vacuum deposition methods depending on the form of the body to be vapor-deposited. 1) Batch method: vapor deposition method of molded products, 2) take-up semi-continuous method: roll film (hereinafter referred to as web) 3) Rewinding system, unwinder (unwinding device) A rewinder (winding device) is disposed in the air system, and a vapor deposition drum and an evaporation source are disposed in a vacuum system to evaporate the evaporated material on the web, and is generally called an air-to-air method. This method is characterized by high productivity.

  When evaporating an evaporated material on the web, a take-up semi-continuous method is particularly popular, and the components of the take-up vacuum deposition apparatus and the outline of the work process are described, and the internal structure of the vacuum deposition apparatus is described. . First, components are a web, an evaporation source, an evaporation substance, a vapor deposition drum, a vacuum system, an unwinder (unwinding device), a rewinder (winding device), a guide roll, and the like.

  Next, the outline of the work process will be described. First, as a preparation, the door of the vacuum vapor deposition apparatus is opened, the web is set on the unwinder (unwinding apparatus), and the guide roll disposed between the unwinder and the vapor deposition drum. The web is caused to travel to the vapor deposition drum through a web, and is further wound around the rewinder (winding device) via a guide roll disposed between the rewinder (winding device), and the vaporized material on the web The preparation for deposition is completed.

  Next, the door of the vacuum deposition apparatus is closed, and the vacuum suction chamber and the vacuum deposition chamber divided by the partition walls in the vacuum deposition apparatus are set to a predetermined vacuum environment by a vacuum pump, and the web is fed out from the unwinder. The evaporation material is heated and evaporated from the evaporation source disposed at the lower part of the evaporation drum on the web that has traveled through the guide roll, and is evaporated onto the web. Since the vapor deposition drum is cooled, the vaporized substance is recrystallized and fixed on the web, and the vapor deposited on the rewinder side guide roll is wound around the rewinder.

  The internal structure of the vacuum deposition apparatus is divided into a vacuum suction constant pressure chamber and a vacuum deposition chamber by partition walls. The vacuum suction constant pressure chamber is composed of an unwinder, guide roll, tension control device, speed control device, position control device, and vapor deposition drum. Some rewinders are arranged.

In the vacuum deposition chamber, a part of the deposition drum, the evaporation source, its heating device, and the like are arranged, and the vacuum suction constant pressure chamber has a degree of vacuum of 1 by a vacuum pump attached to the periphery of the vacuum deposition apparatus main body. × 10 ⁰ MPa about, the vacuum deposition chamber provided via the partition wall is set to a degree 1 × 10 ^-2 MPa (SI units). Since the two chambers are divided by the partition walls, impurities (dust) such as gas generated from the web in the vacuum suction constant pressure chamber are unlikely to adversely affect the deposition in the vacuum deposition chamber. Conversely, the radiant heat from the evaporation source disposed in the vacuum vapor deposition chamber has little influence on the vacuum suction constant pressure chamber, so that the influence of the heat on the web is small.

  The vacuum deposition method is also a heating method: 1) Indirect resistance method, 2) Direct resistance heating method (wire feed method), 3) High frequency induction heating method, 4) Electron beam method (Electoron Beam, EB method for short) 4 There are two methods, but when the evaporated substance uses an insulating metal oxide such as aluminum oxide or silicon oxide, the electron beam method with good energy conversion efficiency is optimal.

  The wound-up electron beam vacuum deposition method is a method of heating the surface of the evaporating material by irradiating the evaporating material directly with an electron beam and scanning the surface of the evaporating material. And evaporating the evaporated substance.

  In addition, when forming the vapor deposition thin film layer of an inorganic oxide on the resin film layer used as the support in the present invention, the resin is used in order to increase the adhesion strength between the resin film layer and the vapor deposition thin film layer composed of the inorganic oxide. It is preferable that the deposition surface of the film layer is subjected to a surface treatment such as corona treatment, a primer layer (not shown) is provided on the treatment surface, and a deposition thin film layer made of an inorganic oxide is provided. Further, it is more preferable to sequentially stack a gas barrier film layer (not shown) on the vapor-deposited thin film layer in order to further improve the barrier property.

  What can be used as a primer layer in order to increase the adhesion strength between the resin film layer and the vapor-deposited thin film layer made of an inorganic oxide is a trifunctional organosilane or a hydrolyzate thereof, an acrylic polyol and an isocyanate compound. Such as composites.

  The composite of the trifunctional organosilane or a hydrolyzate thereof, an acrylic polyol and an isocyanate compound will be described in more detail.

First, the trifunctional organosilane has a general formula, R′Si (OR) ₃ (wherein R ′: amino group, isocyanate group, sulfoxide group, alkyl group, vinyl group, epoxy group, glycidoxypropyl group, etc.) R: an alkyl group), for example, γ-amino-propyltrimethoxysilane, γ-amino-propyltriethoxysilane, γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, ethyl Examples include trimethoxysilane, vinyltrimethoxysilane, glycidoxypropyltrimethoxysilane, glycidoxytrimethoxysilane, and epoxycyclohexylethyltrimethoxysilane. These compounds may be used alone, May be used in a mixture of two or more The trifunctional organosilane used in the present invention may be a hydrolyzate such as the above compound. As a method for obtaining the hydrolyzate, a known method such as a method of performing hydrolysis by directly adding an acid, an alkali or the like to the trifunctional organosilane can be used.

  Next, the acrylic polyol has a hydroxyl group at the terminal out of a polymer compound obtained by polymerizing an acrylic acid derivative monomer or a polymer compound obtained by copolymerization with an acrylic acid derivative monomer and other monomers. It is made to react with the isocyanate group of the isocyanate compound added later. Among them, an acrylic polyol obtained by polymerizing an acrylic acid derivative monomer such as ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, or hydroxybutyl methacrylate alone, or an acrylic polyol copolymerized by adding other monomers such as styrene is preferably used. . In consideration of reactivity with an isocyanate compound, the hydroxyl value is preferably between 5 and 200 (KOHmg / g).

  Next, the blending ratio of the acrylic polyol compound and the trifunctional organosilane is preferably within a range of 1/1 to 100/1 by weight, and more preferably within a range of 2/1 to 50/1. is there.

The dissolving and diluting solvent is not particularly limited as long as it can be dissolved and diluted. For example, esters such as ethyl acetate and butyl acetate, alcohols such as methanol, ethanol and isopropyl alcohol, and ketones such as methyl ethyl ketone. In addition, aromatic hydrocarbons such as toluene and xylene can be used alone or arbitrarily blended. However, since an aqueous solution such as hydrochloric acid or acetic acid may be used to hydrolyze the trifunctional organosilane, a solvent in which isopropyl alcohol or the like and ethyl acetate as a polar solvent are arbitrarily mixed is used as a cosolvent. Is more preferable.

In addition, a reaction catalyst may be added to promote the reaction when the trifunctional organosilane is blended. The catalyst to be added is a tin compound such as tin chloride (SnCl ₂ , SnCl ₄ ), tin oxychloride (SnOHCl, Sn (OH) ₂ Cl ₂ ), tin alkoxide from the viewpoint of reactivity and polymerization stability. Is preferred. These catalysts may be added directly at the time of compounding, or may be added after being dissolved in a solvent such as methanol. If the addition amount is too small or too large, the catalytic effect cannot be obtained, and therefore the molar ratio with respect to the trifunctional organosilane is preferably within a range of 1/10 to 1 / 10,000, and more desirably 1/100. More preferably, it is in the range of ~ 1/2000.

  Furthermore, the isocyanate compound is added in order to increase the adhesion to the resin film layer or the deposited thin film layer by a urethane bond formed by reacting with an acrylic polyol, and mainly acts as a crosslinking agent or a curing agent. . In order to achieve this, the isocyanate compounds include aromatic tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), aliphatic xylylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI). And the like, and polymers and derivatives thereof are used alone or as a mixture.

  The blending ratio of the acrylic polyol and the isocyanate compound is not particularly limited, but if the isocyanate compound is too small, curing may be poor, and if it is too much, blocking or the like occurs and there is a problem in processing. . Therefore, the blending ratio of the acrylic polyol and the isocyanate compound is preferably that the isocyanate group derived from the isocyanate compound (NCO group) is not more than 50 times the hydroxyl group derived from the acrylic polyol (OH group), and particularly preferably the isocyanate group. This is a case where (NCO group) and hydroxyl group (OH group) are blended in equal amounts. As the mixing method, known methods can be used and are not particularly limited.

  Next, as a method of preparing the composite for forming the primer layer, the trifunctional organosilane and acrylic polyol are mixed, a solvent and a diluent are added, diluted to an arbitrary concentration, and then an isocyanate compound. To make a composite mixed solution by mixing with a solvent, or by mixing trifunctional organosilane in a solvent in advance and then mixing acrylic polyol with solvent and diluent to dilute to an arbitrary concentration, then isocyanate There is a method of adding a compound to make a complex mixed solution.

In order to improve the liquid stability during preparation of the composite, a metal alkoxide or a hydrolyzate thereof may be added. The metal alkoxide is a general formula such as tetraethoxysilane [Si (O—C ₂ H ₅ ) ₄ ], tripropoxyaluminum [Al (OC ₃ H ₇ ) ₃ ], or the like, M (OR) n (where M : A metal element such as Si, Zr, Ti or Al, R: an alkyl group such as CH ₃ or C ₂ H ₅ , n: a compound represented by the oxidation number of a metal element), or a hydrolyzate thereof. Among these, tetraethoxysilane, tripropoxyaluminum, or both compounds are preferable because they are relatively stable in an aqueous solvent.

Further, a reaction catalyst may be added to the composite. For example, the catalyst to be added is a tin compound such as tin chloride (SnCl ₂ , SnCl ₄ ), tin oxychloride (SnOHCl, Sn (OH) ₂ Cl ₂ ), tin alkoxide from the viewpoint of reactivity and polymerization stability. Preferably there is.

  Furthermore, various additives such as tertiary amines, imidazole derivatives, carboxylic acid metal chlorides, quaternary ammonium salts, quaternary phosphonium salts and other curing accelerators, and oxidations such as phenols, sulfurs, and phosphites. An inhibitor, a leveling agent, a flow preparation agent, a crosslinking reaction accelerator, a filler, and the like can be added as necessary.

  Next, as a method for forming the primer layer, for example, a known gravure roll coating method, reverse roll coating method, or the like can be used.

  The thickness of the primer layer is not particularly limited as long as a uniform coating film can be formed, but the dry film thickness is preferably in the range of 0.01 to 2 μm. If the thickness is less than 0.01 μm, uniform coating cannot be formed, and stable adhesion cannot be obtained. If the thickness exceeds 2 μm, the coating cannot retain flexibility, and external factors This is not preferred because there is a risk of causing cracks in the coating film. It is particularly preferable that it is in the range of 0.05 to 0.5 μm.

  The primer layer is preferably provided with an aging step after being applied to the resin layer film layer in order to obtain the performance even more sufficiently. You should leave it for about 5 days.

  Next, what is provided on the vapor-deposited thin film layer and can be used as a gas barrier coating layer in order to give a gas barrier property as high as an aluminum foil is a water-soluble polymer, and (a) one or more metals An aqueous solution containing at least one of alkoxide and its hydrolyzate or (b) tin chloride, or a coating agent mainly composed of a water / alcohol mixed solution.

  For example, a solution in which a water-soluble polymer and tin chloride are dissolved in an aqueous (aqueous solution or water / alcohol mixed solution) solvent, or a solution in which a metal alkoxide is directly or previously hydrolyzed and mixed. Is formed by coating the vapor-deposited thin film layer and heating and drying.

  Examples of the water-soluble polymer include polyvinyl alcohol (PVA), polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, and sodium alginate.

  In particular, polyvinyl alcohol (PVA) is preferable because it has excellent gas barrier properties. Polyvinyl alcohol (PVA) here is generally obtained by saponifying polyvinyl acetate, and for example, several tens percent of acetate groups remain. In other words, it is not particularly limited and includes completely saponified polyvinyl alcohol (PVA) in which only a few percent of acetic acid groups remain from so-called partially saponified polyvinyl alcohol (PVA).

  The tin chloride is stannous chloride, stannic chloride, or a mixture thereof, and anhydrides and hydrates of these tin chlorides can also be used.

Next, the metal alkoxide and the hydrolyzate thereof include general formulas such as tetraethoxysilane [Si (O—C ₂ H ₅ ) ₄ ], tripropoxy aluminum [Al (OC ₃ H ₇ ) ₃ ], M ( OR) a compound represented by n (wherein M: a metal element such as Si, Zr, Ti or Al, R: an alkyl group such as CH ₃ or C ₂ H ₅ , n: the oxidation number of the metal element), or The hydrolyzate. Among these, tetraethoxysilane, tripropoxyaluminum, or both compounds are preferable because they are relatively stable in an aqueous solvent.

Furthermore, known additives such as isocyanate compounds, silane coupling agents, or dispersants, stabilizers, viscosity modifiers, colorants and the like are added to the coating agent as necessary, as long as the gas barrier properties are not impaired. Can be added.

  As the isocyanate compound added to the coating agent, those having two or more isocyanate groups in the molecule are preferable. Examples of such isocyanate compounds include monomers such as tolylene diisocyanate, triphenylmethane triisocyanate, and tetramethylxylene diisocyanate, and polymers and derivatives thereof.

  The gas barrier coating layer is formed on the deposited thin film layer by applying a known method such as a gravure roll coating method, reverse roll coating method, air knife coating method, etc., followed by heating and drying.

  In this case, the thickness of the gas barrier coating layer is preferably in the range of 0.01 to 50 μm after drying. When the thickness after drying is 0.01 μm or less, sufficient gas barrier properties cannot be obtained, and when it is 50 μm or more, the coating film is liable to crack and adversely affects the gas barrier.

  For the barrier layer (2) constituting the packaging base paper in the present invention, an inorganic oxide vapor-deposited film having a layer constitution of the aforementioned resin film layer / primer layer / deposited thin film layer / gas barrier coating layer is more preferably used.

  Next, as the sealant layer (3) provided on the barrier layer (2), the sealant layer (3) serves as an adhesive layer when molding the paper container or the like. The thermoplastic resin similar to the resin used for the outer layer can be used.

  For example, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, Polyolefin resins such as ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, methylpentene polymer, polybutene polymer, polyethylene or polypropylene are treated with acrylic acid, methacrylic acid, maleic acid, anhydrous Use resins such as acid-modified polyolefin resins modified with unsaturated carboxylic acids such as maleic acid, fumaric acid, and itaconic acid, polyvinyl acetate resins, poly (meth) acrylic resins, polyvinyl chloride resins, etc. In That is, workability, from the standpoint of economic efficiency, it is preferable to use a low density polyethylene.

  Next, in the method of forming the sealant layer (3) on the barrier layer (2), a sealant film prepared by previously forming the resin is used, and the barrier layer (6) is interposed through the adhesive layer (6). 2) The barrier layer by a method of forming a sealant layer (3) on the barrier layer (2) and an extrusion lamination method (melt extrusion lamination method) in which a thermoplastic resin such as low density polyethylene is melt extruded and laminated directly on the barrier layer (2). (2) There is a method of forming a sealant layer (3) on top. It is preferable that the thickness of the sealant layer (3) is arbitrarily selected within a range of about 20 to 100 μm.

  For example, a dry lamination method, a non-solvent dry lamination method, a hot lamination method can be used to form the sealant layer (3) via the adhesive layer (6) using a sealant film prepared by previously forming the above resin. A known method such as a melt lamination method or a sand lamination method using an extrusion lamination method can be used.

  For example, the dry lamination method is a method of laminating using an adhesive for laminating polyurethane, polyester, epoxy, polyacryl, polyvinyl acetate, cellulose, etc. for the adhesive layer (6). It is. It consists of three sections: a coating part for applying the adhesive on the barrier layer (2), a drying device, and a nip roller part, and an unwinding, winding and tension control system. The coating portion generally employs a gravure roll coating method, a reverse roll coating method, or the like.

  As the lamination adhesive, a solvent type adhesive or a solventless type adhesive is used. However, when a solventless type adhesive is used, a drying apparatus is not necessary, and this is called a non-solvent dry lamination method. Yes.

  Next, the hot melt lamination method uses a hot melt adhesive such as ethylene-vinyl acetate copolymer (EVA) melted by heating to the adhesive layer (6), and is applied onto the barrier layer (2). Immediately, the sealant film is laminated.

  The sand lamination method using the extrusion lamination method is a method of laminating the barrier layer (2) and the sealant layer (3) using a thermoplastic resin such as polyethylene for the adhesive layer (6). . That is, the thermoplastic resin is heated, melted in a cylinder called a cylinder, extruded by applying pressure with a screw, and the resin dissolved in a curtain shape from a thin slit called a T die at the tip of the cylinder is used as a barrier. This is a method in which a sealant layer (3) is provided by extruding between a layer (2) and a sealant layer (3) and laminating a sealant film on the barrier layer (2).

  Next, the inorganic oxide vapor deposition film surface of the paper layer (1c) surface of the multilayer paper (1) having the outermost thermoplastic resin layer (4) and the barrier layer (2) having the innermost sealant layer (3). For example, a known lamination method such as a sand lamination method using an extrusion lamination method, a dry lamination method, a non-solvent dry lamination method, or a hot melt lamination method can be used.

  For example, in the sand lamination method using the extrusion lamination method, as described above, a thermoplastic resin such as polyethylene is used for the adhesive layer (5), the thermoplastic resin is heated, and the cylinder is called a cylinder. The resin dissolved in a curtain shape from a thin slit called a T-die at the tip of the cylinder is extruded with pressure applied with a screw and the paper layer (1c) surface of the multilayer paper (1) and the barrier layer Extrusion between the inorganic oxide vapor deposition film surface of (2), the paper layer (1c) surface of the multilayer paper (1) having the outermost thermoplastic resin layer (4) and the innermost sealant layer (3) It is the method of laminating the inorganic oxide vapor deposition film surface of the barrier layer (2) to have.

As the adhesive layer (5), as described above, for example, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene -Acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, methylpentene polymer, polybutene polymer, polyethylene or polypropylene Polyolefin resins such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, and other acid-modified polyolefin resins, polyvinyl acetate resins, poly (meth) acrylic resins Resin, polyvinyl Resin, it may be used resins such as other. It is preferable that the thickness of the adhesive layer (5) is arbitrarily selected within a range of about 20 to 60 μm.

  Next, as described above, the dry lamination method uses an adhesive for laminate such as polyurethane, polyester, epoxy, polyacryl, polyvinyl acetate, cellulose, etc. for the adhesive layer (5). This is a method of lamination. It consists of three sections: a coating part for applying the adhesive on the multilayer paper (1), a drying device, and a nip roller part, and an unwinding, winding and tension control system. The coating portion generally employs a gravure roll coating method, a reverse roll coating method, or the like.

  As described above, a solvent type adhesive or a solventless type adhesive is used as the lamination adhesive. However, when a solventless type adhesive is used, a drying device is not required and a nonsolvent dry lamination is used. Called the method.

  In the hot melt lamination method, a paper layer (1c) of a multilayer paper (1) having a thermoplastic resin layer (4) as an outermost layer of a hot melt adhesive such as a heat-melted ethylene-vinyl acetate copolymer (EVA). It is a method in which the film is applied to the surface and immediately laminated with the inorganic oxide vapor-deposited film surface of the barrier layer (2) having the innermost sealant layer (3).

  As described above, the inorganic oxide vapor deposition of the paper layer (1c) surface of the multilayer paper (1) having the outermost thermoplastic resin layer (4) and the barrier layer (2) having the innermost sealant layer (3). As a method of laminating the film surface, a known method such as a sand lamination method using an extrusion lamination method, a dry lamination method, a non-solvent dry lamination method, or a hot melt lamination method can be used. From the viewpoint of production cost and the like, a sand lamination method using a thermoplastic resin and utilizing an extrusion lamination method (melt extrusion lamination method) is preferable.

  A blank is produced by punching the packaging base paper produced as described above, a sleeve is produced by side-pasting this blank with a special sack pasting machine (frame sealer), and this sleeve is used as a filling molding machine. The liquid paper container prepared by loading has a space (S) in which the multilayer paper (1) constituting the packaging base paper escapes water vapor (V) generated from paper heated by hot air (H) during molding. Since it has a special structure, there is no foaming phenomenon due to the water vapor (a phenomenon that the layers are separated and lifted), and the gas barrier property is excellent, so that the contents can be stored for a long period of time. Similarly, a cup produced by loading a blank produced using the above wrapping base paper into a cup molding machine does not have a foaming phenomenon due to the water vapor (a phenomenon in which the interlayer peels off and rises), and has an excellent gas barrier property. The contents can be stored for a long time.

  Hereinafter, the present invention will be described in more detail with reference to specific examples.

  As shown in FIG. 1, the packaging base paper (A) of the present invention is composed of (outermost layer side) thermoplastic resin layer (4) / multilayer paper (1) [paper layer (1a) / resin layer (1b) / Paper layer (1c)] / adhesive layer (5) / barrier layer (2) / adhesive layer (6) / sealant layer (3) (innermost layer side).

First, a paperboard with a basis weight of 300 g / m ² was used for the paper layer (1a), and a paper with a basis weight of 100 g / m ² was used for the other paper layer (1c). As a resin layer (1b) serving as an adhesive on one side of the paperboard as the paper layer (1a), a low density polyethylene (LDPE) is used and a thickness of 20 μm is obtained by an extrusion lamination method. Multi-layer paper (1) having a space (S) for extruding water vapor (V) between the paper layers (1a, 1c) by extruding into a linear shape and bonding with the paper as the other paper layer (1c). ) Was produced.

  Subsequently, the low-density polyethylene (LDPE) is used as the thermoplastic resin layer (4) on the surface not contacting the resin layer (1b) of the paperboard constituting the multilayer paper (1). A thermoplastic resin layer (4) was provided by extrusion at a thickness of 20 μm by a lamination method.

  Next, as a barrier layer (2) in a separate step, a polyethylene terephthalate film (hereinafter referred to as PET) having a thickness of 12 μm is used, and a dilution solvent (ethyl acetate) is used as a primer layer on the corona-treated surface of the PET. A gravure roll is a composite solution in which a mixed solution obtained by adding tolylene diisocyanate (TDI) as an acrylic polyol and an isocyanate compound so that the NCO group is equivalent to the OH group of the acrylic polyol is diluted to an arbitrary concentration. A coating having a thickness of 0.1 μm was formed by a coating method.

Next, a vapor-deposited PET film in which a 50 nm-thick silicon oxide thin film was provided on the primer layer by an electron beam heating vacuum deposition method was produced. Subsequently, 89.6 g of hydrochloric acid (0.1N) was added to 10.4 g of tetraethoxysilane as a gas barrier coating layer on the vapor-deposited surface of the vapor-deposited PET film, stirred for 30 minutes, and hydrolyzed solid content of 3% by weight ( SiO ₂ equivalent hydrolysis solution and polyvinyl alcohol (PVA) 3 wt% water / isopropyl alcohol solution (water: isopropyl alcohol weight ratio 90:10) were mixed at a blending ratio (wt%) 60:40. The resulting coating agent was applied by a reverse roll coating method and dried at 120 ° C. for 1 minute in a dryer to form a film having a thickness of about 0.3 μm.

  Next, a polyester resin adhesive is applied to the above-described gas barrier coating layer of the barrier layer (2) as a bonding layer (6) by a reverse roll coating method to a thickness of 1 μm, and then a low density polyethylene. (LDPE) was extruded by an extrusion lamination method at a thickness of 60 μm to provide a sealant layer (4), and a laminated film of barrier layer (2) / adhesive layer (6) / sealant layer (3) was produced.

  The side of the multilayer film (1) not provided with the laminated film of the barrier layer (2) / adhesive layer (6) / sealant layer (3) and the thermoplastic resin layer (4) of the multilayer paper (1) prepared as described above. Using an ethylene-methacrylic acid copolymer (EMAA) as an adhesive layer (5), extrusion lamination was performed at a thickness of 30 μm by sand lamination to produce a packaging base paper (A).

  That is, the packaging base paper (A) is (outermost layer side) thermoplastic resin layer (4) / multilayer paper (1) [paper layer (1a) / resin layer (1b) / paper layer (1c)] / adhesive layer It is a laminated material having a multilayer structure of (5) / barrier layer (2) / adhesive layer (6) / sealant layer (3) (innermost layer side).

  The packaging base paper (A) produced as described above was punched to produce a blank, and this blank was side-attached with a special sack application machine (frame sealer) to produce a sleeve. Even if water vapor (V) is generated in the wrapping base paper (A) by the hot air (H) during molding, the liquid paper container produced by loading into the filling molding machine using this sleeve is free from the water vapor (V ) Did not occur (a phenomenon where the layers peeled and separated).

In Example 1, the paper used for the paper layers (1a, 1c) constituting the multilayer paper (1) is the same as Example 1 except that both paper layers have a basis weight of 100 g / m ^2. A base paper for packaging (A) is produced, and a blank is produced by punching the base paper for packaging (A), and the cup produced by using this blank is loaded into a cup molding machine. Even if water vapor (V) was generated in the wrapping base paper (A) by H), the foaming phenomenon (a phenomenon in which the interlayer peeled off and floated up) due to the water vapor (V) did not occur.

It is a sectional side view which shows one Example of the layer structure of the packaging base paper based on this invention.

Explanation of symbols

A ... Packaging paper S ... Space H ... Hot air V ... Water vapor 1 ... Multi-layer paper 1a ... Paper layer 1b ... Resin layer 1c ... Paper layer 2 ... Barrier layer 3 ... Sealant layer 4 ... Thermoplastic resin layer 5 ... Adhesive layer 6 ... Adhesive layer

Claims (5)

  A thermoplastic resin layer is provided on the surface of the multilayer paper obtained by interleaving the paper layer and the paper layer through a linearly extruded resin layer on the side not contacting the resin layer of one of the paper layers, and A packaging base paper characterized in that at least a barrier layer and a sealant layer are sequentially laminated on the surface of the other paper layer that does not contact the resin layer.   The packaging base paper according to claim 1, wherein the barrier layer is a resin film having at least a deposited thin film layer made of an inorganic oxide.   The packaging base paper according to claim 2, wherein the inorganic oxide is made of aluminum oxide or silicon oxide.   A liquid paper container using the packaging base paper according to any one of claims 1 to 3.   A cup using the packaging base paper according to any one of claims 1 to 3.

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