JP2012206472A - Gas barrier laminate, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas barrier laminate wherein oxygen barrier property as a packaging bag is excellent, and a metal detector can be used, and which can be discarded as a paper.SOLUTION: The gas barrier laminate is a gas barrier laminate formed by arranging at least one gas barrier layer containing a water-soluble polymer and an inorganic layered compound on a paper support, and a polyoxyethylene polyoxypropylene block polymer is contained in the gas barrier layer. The method for manufacturing the gas barrier laminate includes adding the polyoxyethylene polyoxypropylene block polymer before and/or during temperature rise when dissolving the water-soluble polymer.

Description

  The present invention is a packaging material for packaging foods, in particular, a packaging material for packaging contents that may react with oxygen and cause oxidation or deterioration, and a metal detector can be used, The present invention provides a packaging material that can be separated as paper after use.

  In general, when food comes into contact with oxygen, components such as oil contained in the food react (oxidize) with oxygen to change the taste of the food or cause discoloration. Therefore, many foods are packaged with a packaging material having gas barrier properties (particularly oxygen barrier properties). Conventionally, as such a packaging material, silica or alumina on a gas barrier film, PET (polyethylene terephthalate) film or nylon film in which polyvinylidene chloride (hereinafter abbreviated as PVDC) or PVA layer is provided on OPP (biaxially stretched polypropylene). There is a gas barrier film provided with an inorganic oxide layer or an aluminum metal layer, and a gas barrier laminate in which a paper base and an aluminum foil or a paper base and the gas barrier film are bonded. Gas barrier laminates using paper as a base material are characterized by excellent printability, moderate rigidity, and a high-class feeling, and are widely used as packaging materials.

  However, when a film having an aluminum foil or an aluminum vapor deposition layer and a paper substrate are bonded, there is a problem that a metal detector for inspection of foreign matter after food packaging cannot be used because it contains metal. Moreover, since it contains metal, it cannot be incinerated as paper and cannot be reused as waste paper. On the other hand, when a film having a gas barrier layer such as PVA, PVDC, or an inorganic oxide is used, the cost is increased, and the laminate of the film and paper is often inferior in packaging suitability and workability. The present situation is that most of the gas barrier laminates of the paper base material use an aluminum foil and paper base laminate. On the other hand, a technique for forming a gas barrier layer using a polyvinyl alcohol resin on the surface of a paper substrate has been conventionally proposed. Patent Document 1 proposes a method of providing polyvinyl alcohol and an inorganic layered compound on a paper substrate. Patent Document 2 proposes, similarly to Patent Document 1, a laminated paper for packaging provided with a paper layer and a resin composition layer having an inorganic layer compound on the paper layer. Patent Document 3 proposes a paper composite having, on at least one surface of paper, a resin composition layer containing 0.01 to 200 parts by weight of a layered inorganic compound with respect to 100 parts by weight of a water-soluble polymer compound. Yes. Patent Document 4 discloses an ethylene-vinyl ester copolymer saponified product (A) having an ethylene content of 1 to 15 mol%, an ethylene-vinyl ester copolymer saponified product (B) having an ethylene content of 15 to 70 mol%, and A resin composition comprising an inorganic layered compound (C) has been proposed. In Patent Document 5, in a laminate comprising a coating layer 1, a barrier layer 2, and a paper base material 3, the barrier layer 2 is a paper or biaxially stretched film base material B and vinyl alcohol having an ethylene content of 0 to 15 mol%. A laminate comprising a layer A of a polymer is proposed. Patent Document 6 discloses a gas barrier laminate in which a first gas barrier layer and a second gas barrier layer containing a water-soluble polymer and an inorganic layered compound are provided in this order on a paper support. The mass ratio of the water-soluble polymer to the inorganic stratiform compound is 75/25 to 50/50, and the mass ratio of the water-soluble polymer to the inorganic stratiform compound in the second gas barrier layer is 95/5 to 75 / A gas barrier laminate of 25 is proposed. In Patent Document 7, in a gas barrier laminate in which a gas barrier layer containing a water-soluble polymer, an inorganic layered compound, and a synthetic resin is provided on a paper support, the inorganic layered compound is used with respect to 100 parts by mass of the water-soluble polymer. Proposed is a gas barrier laminate in which 10 to 150 parts by mass and 5 to 100 parts by mass of a synthetic resin are proposed. Patent Document 8 proposes a gas barrier laminate in which a first gas barrier layer containing an ethylene-modified polyvinyl alcohol resin and an inorganic layered compound and a second gas barrier layer made of ethylene-modified polyvinyl alcohol are sequentially provided on a paper support. ing. However, the gas barrier laminate composed of such a polyvinyl alcohol-based resin has a problem that the gas barrier property is lowered when a coating defect occurs during coating.

  In general, water-soluble polymers such as polyvinyl alcohol are easy to foam during the heating process at the time of dissolution, and the generated foam is difficult to disappear, the tank liquid level rises, and there is a possibility that the dissolved liquid overflows, so it dissolves to prevent overflow. It is necessary to take measures to reduce the amount, and work efficiency is lowered. In addition, paints mainly composed of water-soluble polymers such as polyvinyl alcohol tend to foam, and if the foam is applied to the coating surface, coating defects will occur, or if foaming is severe, gas barriers will occur by causing coating unevenness. May decrease the performance.

The addition of an antifoaming agent for the purpose of improving the foaming of the paint has been proposed for various coatings for coated paper. For example, in an inkjet recording paper coating, a method of adding a fatty acid ester, ether, metal soap, or silicone defoamer to a polyvinyl alcohol coating (Patent Document 9), or a hydrophobic silica based coating to a polyvinyl alcohol coating. Examples include a method of adding a foaming agent (Patent Document 10).
Although the foaming of the paint is suppressed by adding these antifoaming agents, the antifoaming agent itself forms a hydrophobic part on the coating surface, and generates a non-coating part (so-called repellency) of the gas barrier laminate paint. Therefore, the gas barrier properties may be impaired, so that the actual situation is that satisfactory gas barrier properties cannot be obtained even when these antifoaming agents are applied to the gas barrier laminate coating.

JP 11-129381 A JP-A-11-309817 JP-A-13-214396 Japanese Patent Application Laid-Open No. 14-069255 Japanese Patent Laid-Open No. 15-094574 JP 2007-216592 A JP 2007-216593 A JP 2009-184138 A Japanese Patent Laid-Open No. 11-277877 JP 2009-84404 A

  The present invention suppresses foaming during dissolution of the polyvinyl alcohol-based resin to prevent operability deterioration, and also prevents deterioration of operability due to foaming of the paint when applying a gas barrier coating, thereby generating surface defects. An object of the present invention is to provide a gas barrier laminate having excellent gas barrier properties by being suppressed.

  As a result of diligent studies to solve the above problems, the present inventor has added a polyoxyethylene polyoxypropylene block polymer having a specific structure to the gas barrier coating layer paint, thereby generating foam when dissolving the water-soluble polymer. It has been found that excellent gas barrier properties are manifested by suppressing the decrease in operability due to foaming, preventing the decrease in operability due to foaming of the paint during coating, and suppressing the occurrence of surface defects, leading to the completion of the present invention. It was. The present invention includes the following inventions.

(1) A gas barrier laminate in which at least one gas barrier layer containing a water-soluble polymer and an inorganic layered compound is provided on a paper support, the polyoxyethylene polyoxypropylene block polymer being contained in the gas barrier layer Gas barrier laminate.

(2) A first gas barrier layer containing a water-soluble polymer and an inorganic stratiform compound and a second gas barrier layer mainly composed of the water-soluble polymer are sequentially provided on the paper support, and the first gas barrier layer and A gas barrier laminate in which a polyoxyethylene polyoxypropylene block polymer is contained in the second gas barrier layer.

(3) The gas barrier laminate according to (1) or (2), wherein the polyoxyethylene polyoxypropylene block polymer is a polyoxyethylene (3 to 10 mol addition) polyoxypropylene (25 to 35 mol addition) block polymer. body.

(4) The gas barrier laminate according to any one of (1) to (3), wherein the water-soluble polymer is a polyvinyl alcohol resin.

(5) The polyoxyethylene polyoxypropylene block polymer is contained in an amount of 0.01 to 1.0 part by mass with respect to 100 parts by mass of the water-soluble polymer, according to any one of (1) to (4). Gas barrier laminate.

(6) The gas barrier laminate according to (4), wherein the polyvinyl alcohol resin is ethylene-modified polyvinyl alcohol.

(7) The gas barrier laminate according to any one of (1) to (6), wherein a mass ratio of the water-soluble polymer to the inorganic layered compound is 99: 1 to 50:50.

(8) The gas barrier laminate according to (3), wherein the polyoxyethylene polyoxypropylene block polymer is a polyoxyethylene (5 mol addition) polyoxypropylene (30 mol addition) block polymer.

(9) A method for producing a gas barrier laminate, wherein the polyoxyethylene polyoxypropylene block polymer is added before and / or during temperature rise when the water-soluble polymer is dissolved.

  According to the present invention, the efficiency of dissolving the water-soluble polymer is improved, and at the time of applying the gas barrier layer coating, it is possible to prevent deterioration in operability due to foaming of the coating and to suppress the occurrence of surface coating defects. A gas barrier laminate is obtained.

The present invention is described in detail below.
In the present invention, a polyoxyethylene polyoxypropylene block polymer is contained in at least one gas barrier layer. Various block polymers are known for the polyoxyethylene polyoxypropylene block polymer. In the present invention, polyoxyethylene (3 to 3) is used as the block polymer from the viewpoint of foam suppression with respect to a water-soluble polymer such as polyvinyl alcohol resin. 10 mol addition) polyoxypropylene (25-35 mol addition) block polymer is preferably used. Among them, polyoxyethylene (5 mole addition) polyoxypropylene (30 mole addition) block polymer is effective for foaming when dissolving water-soluble polymers such as polyvinyl alcohol resin and foaming when applying gas barrier layer paint. This is particularly preferable. Specific examples include “Pepol B” series manufactured by Toho Chemical Co., Ltd. and “Epan” series manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

In the present invention, the addition amount of the polyoxyethylene polyoxypropylene block polymer added to the gas barrier layer is preferably 0.01 to 1.0 part by mass, more preferably 100 parts by mass with respect to 100 parts by mass of the water-soluble polymer. 0.05 to 0.5 parts by mass.
When the addition amount of the polyoxyethylene polyoxypropylene block polymer is less than 0.01 parts by mass, a satisfactory defoaming effect may not be obtained. Moreover, when it exceeds 1.0 mass part, there exists a possibility that a gas barrier may be generated on a coating surface and gas barrier property may fall.

Examples of the water-soluble polymer used in the present invention include starch and derivatives thereof, cellulose derivatives, polyvinylpyrrolidone, urethane resins, polyacrylic acid and salts thereof, casein, polyethyleneimine, polyvinyl alcohol resins, and modified polyvinyl alcohol resins. Etc. can be exemplified.
Of these, unmodified fully saponified polyvinyl alcohol resin, partially saponified polyvinyl alcohol resin and modified polyvinyl alcohol resin are preferable. Examples of the modified polyvinyl alcohol include ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, diacetone group-modified polyvinyl alcohol, etc., but ethylene-modified polyvinyl alcohol (for example, trade name: “ “Exebar” series (manufactured by Kuraray Co., Ltd.) is particularly preferable because of its excellent gas barrier properties.

  In the present invention, the polyoxyethylene polyoxypropylene block polymer can be added before the temperature increase and / or during the temperature increase when the water-soluble polymer is dissolved, thereby suppressing foaming during the dissolution of the water-soluble polymer. The defoaming effect is not impaired by heating, which is preferable. Of course, it can be directly added to the dissolved polymer aqueous solution or gas barrier layer coating to obtain a foam-suppressing effect during coating.

  When a water-based coating containing a water-soluble polymer such as a polyvinyl alcohol resin and a swellable inorganic layered compound such as montmorillonite is applied onto a paper support to form a barrier layer, the curved layer effect of the inorganic layered compound results. , The barrier properties are greatly improved. However, in order to exhibit high barrier properties, it is necessary to increase the blending amount of the inorganic layered compound, but when the inorganic layered compound exceeds a certain amount, the adhesion strength and coating strength of the barrier layer are significantly reduced. The present inventor found out. The adhesion strength of the barrier layer here refers to the adhesion strength between the barrier layer and the sealant layer when the barrier layer and the sealant layer are laminated. If the adhesion strength is weak, not only the heat seal strength after packaging will be weak, but also a gap will be formed at the interface between the sealant layer and the barrier layer, and air will permeate through that part, greatly improving the oxygen barrier property as a packaging bag. It turned out to be reduced.

  Therefore, in the present invention, at least one gas barrier layer containing a water-soluble polymer such as polyvinyl alcohol resin and an inorganic layered compound is provided on the surface of the paper substrate, or a water-soluble polymer such as polyvinyl alcohol resin and an inorganic layered compound. Adhesive strength between the barrier layer and the sealant layer is improved by sequentially providing a first gas barrier layer containing a second gas barrier layer made of a water-soluble polymer such as a polyvinyl alcohol resin.

  The first gas barrier layer may contain a synthetic resin such as a styrene-butadiene copolymer latex or an acrylic acid alkyl ester-styrene copolymer emulsion in addition to a water-soluble polymer such as a polyvinyl alcohol resin. .

  The second gas barrier layer is mainly composed of a water-soluble polymer such as a polyvinyl alcohol-based resin, but various synthetic resins and the like can be added as necessary within a range not hindering the effect. As the synthetic resin that can be added and used, those that can be used in the first gas barrier layer can be similarly used. In the present invention, the inorganic layered compound is not added to the second gas barrier layer because it interferes with the polyolefin base material.

  In the present invention, a hydrogen bonding group crosslinking agent can be added to the gas barrier layer for the purpose of improving the coating strength.

  Although it does not specifically limit as a crosslinking agent for hydrogen bondable groups which can be used by this invention, For example, a titanium coupling agent, a silane coupling agent, a melamine coupling agent, an epoxy coupling agent, an isocyanate type cup Examples thereof include a ring agent, a copper compound, a zirconium compound, a boron compound, and colloidal silica. Among these, a zirconium compound and a boron compound are more preferably used. Specific examples of the zirconium compound include zirconium halides such as zirconium oxychloride, hydroxyzirconium chloride, zirconium (IV) chloride and zirconium bromide, zirconium salts of mineral acids such as zirconium sulfate, basic zirconium sulfate and zirconium nitrate. Zirconium salts of organic acids such as zirconium formate, zirconium acetate, zirconium propionate, zirconium caprylate, zirconium stearate, ammonium zirconium carbonate, sodium zirconium sulfate, ammonium zirconium acetate, sodium zirconium oxalate, sodium zirconium citrate, zirconium citrate Examples include zirconium complex salts such as ammonium.

  The gas barrier layer may contain a wetting agent, a dye, a color adjusting agent, a thickener, and the like as necessary.

In the present invention, the coating amount of the gas barrier layer containing the water-soluble polymer and the inorganic layered compound is preferably 0.5 to 5.0 g / m ² . If the coating amount is less than 0.5 g / m ² , there is a possibility that the oxygen barrier property is lowered or the coating film strength is lowered. If it exceeds 5 g / m ² , the adhesion strength and the coating film strength may be lowered, which is not preferable.
Moreover, 0.1-3.0 g / m < ² > is preferable and, as for the coating amount of a 1st gas barrier layer, 0.5-2.5 g / m < ² > is more preferable. If the coating amount of the first gas barrier layer exceeds 3.0 g / m ² , the coating strength may be significantly reduced, and if it is less than 0.1 g / m ² , the oxygen barrier property may be insufficient. There is. Further, the coating amount of the second gas barrier layer is preferably from 0.1 to 3.0 g / ^{m 2,} more preferably 0.5 to 2.5 g / ^{m 2.} If the coating amount of the second gas barrier layer exceeds 3.0 g / m ² , the coating strength may decrease, and if it is less than 0.1 g / m ² , the adhesion strength with the sealant layer becomes insufficient, There is also a possibility that the oxygen barrier property is also lowered. The total coating amount of the first gas barrier layer and the second gas barrier layer is preferably 0.2 to 6 g / m ² , and more preferably 0.5 to 5 g / m ² . If the total coating amount is less than 0.2 g / m ² , the oxygen barrier property may be lowered or the coating film strength may be lowered. Moreover, when it exceeds 6 g / m < ² >, there exists a possibility that adhesive strength and coating-film intensity | strength may fall, and it is unpreferable.

  Specific examples of inorganic layered compounds that can be used in the present invention include graphite, phosphate derivative compounds (such as zirconium phosphate compounds), chalcogenides, hydrotalcite compounds, lithium aluminum composite hydroxides, clays. Minerals, synthetic mica, synthetic smectite and the like can be mentioned. Graphite, phosphate derivative compounds (zirconium phosphate compounds, etc.), chalcogenides, hydrotalcite compounds, and lithium aluminum composite hydroxides are compounds or substances in which unit crystal layers are stacked on each other and have a layered structure. Here, the layered structure refers to a structure in which surfaces in which atoms are strongly bonded by a covalent bond or the like and densely arranged are stacked substantially in parallel by a weak binding force such as van der Waals force.

A “chalcogenide” is a dichalcogenide of a group IV (Ti, Zr, Hf), group V (V, Nb, Ta) and / or group VI (Mo, W) element, which has the formula MX ₂ (M is The above element, X represents a chalcogen (S, Se, Te). Clay-based minerals generally have a two-layer structure having an octahedral layer with aluminum, magnesium, etc. as the central metal at the top of the silica tetrahedral layer, and a silica tetrahedral layer, with aluminum, magnesium, etc. It is classified into a type having a three-layer structure in which an octahedral layer made of a central metal is sandwiched from both sides. Examples of the former two-layer structure type include kaolinite group and antigolite group. Examples of the latter three-layer structure type include smectite group, vermiculite group, mica group, etc. depending on the number of interlayer cations. Can do. Examples of these clay minerals include clay minerals such as smectite group and vermiculite group. More specifically, kaolinite, dickite, nacrite, halloysite, antigolite, chrysotile, pyrophyllite, montmorillonite, hectorite, tetrasilic mica, sodium teniolite, margarite, talc, vermiculite, xanthophyllite, Chlorite and the like can be mentioned. References such as Haruo Shiramizu's “Clay Mineralogy” (Asakura Shoten, 1988) can also be referred to. Smectite is particularly preferable, and examples of the smectite include montmorillonite, hydelite, nontronite, saponite, iron saponite, hectorite, soconite, and stevensite.

In addition to the clay mineral (natural product), it may be a synthetic product or a processed product (for example, a surface-treated product of a silane coupling agent). As the synthetic smectite, the formula Na _{0.1-1.0 mg 2.4~2.9 Li 0.0~0.6 Si 3.5~4.0 O 9.0~10.6} (OH and / or _F) those represented by _{1.5 to 2.5} Is mentioned. There are three methods for producing synthetic smectite and synthetic mica, namely, a hydrothermal reaction method (JP-A-6-345419), a solid-phase reaction method, and a melting method (see JP-A-5-270815). In the hydrothermal reaction method, an aqueous solution or aqueous slurry containing various raw materials such as silicate, magnesium salt, alkali metal ion, alkali metal salt, and fluorine ion is heated at a high temperature of 100 to 400 ° C. and high pressure in an autoclave or pipe reactor. It is a method of reacting and synthesizing. In the hydrothermal reaction method, since the crystal growth is slow and large particles cannot be obtained, in general, most particles have a particle size of 10 to 100 nm. Of course, even in hydrothermal reaction, large particles with a particle size of 1 μm or more can be produced if they are synthesized under conditions of low concentration, low temperature and long time, but there is a problem that the production cost becomes extremely high. .

  The solid phase reaction method is a method for producing synthetic mica by reacting with talc, alkali silicofluoride and other raw materials for several hours in the range of 400 to 1000 ° C. In solid phase reaction, element migration occurs while leaving the talc structure of the raw material, and mica is produced (topotaxy), so the quality of the resulting synthetic mica depends on the talc physical properties of the raw material and its impurities, Since it cannot be controlled, there is a problem that the purity and crystallinity of synthetic mica are low. In the melting method, anhydrous silicic acid, magnesium oxide, aluminum oxide, potassium silicofluoride, potassium carbonate, and other raw materials are melted at a melting point (for example, 1500 ° C.) or higher of mica and then slowly cooled to crystallize synthetic mica and synthetic smectite. It is a manufacturing method. Also, depending on the heating method, there are an external heating type melting method and an internal heating type melting method. The external heating type melting method is a method in which a crucible containing raw materials is put into a chamber having a temperature higher than the melting point and heated to move to a chamber having a temperature lower than the melting point, but the crucible is expensive. There is a problem. The internal heating type melting method is a method in which a raw material is heated and melted by energization in a vessel equipped with a graphite (carbon) electrode or a metal electrode, and then cooled. In the fusion method, the internal heating type melting method is generally used. It is. The melt fusion method can produce a synthetic product having a controlled particle size by pulverizing and classifying the cooled and crystallized mass. The fusion method can use raw materials with high purity as raw materials, and since the raw materials can be mixed uniformly, it produces high-crystallinity, large particle size, high-purity synthetic mica and synthetic smectite. There is an advantage that can be done.

Examples of the synthetic inorganic layered compound include fluorine phlogopite (KMg ₃ AlSi ₃ O ₁₀ F, melting method or solid phase reaction method), potassium tetrasilicon mica (KMg _2.5 Si ₄ O ₁₀ F ₂ , melting method), sodium tetra Silicon mica (NaMg _2.5 Si ₄ O ₁₀ F ₂ , melting method), sodium teniolite (NaMg ₂ LiSi ₄ O ₁₀ F ₂ , melting method), lithium teniolite (LiMg ₂ LiSi ₄ O ₁₀ F ₂ , melting method) ), Etc., sodium hectorite (Na _0.33 Mg _2.67 Li _0.33 Si _4.0 O ₁₀ (OH or F) ₂ , hydrothermal reaction method or melting method), lithium hectorite (Na _{0) .33 Mg 2.67 Li 0.33 Si 4.0 O} 10 (OH or F) _2, hydrothermal reaction method or a fusion method), saponite _{(Na 0.33} Mg _{2 67 AlSi 4.0 O 10 (OH)} 2, hydrothermal reaction method) and synthetic smectite such. As commercial products of clay minerals, natural bentonite commonly called sodium bennite, kunipia (natural montmorillonite, manufactured by Kunimine Industry Co., Ltd.), smecton (hydrothermal reaction method synthetic smectite, manufactured by Kunimine Industry Co., Ltd.), bee gum (trademark: Vanderbilt) Laponite (trade name: manufactured by Laporte), DM Clean A, DMA-350, Na-Ts, NTO-5 (melting method, sodium tetrasilicon mica, trademark: manufactured by Topy Industries), Bengel (trade name: Yutaka) Junyo Co., Ltd.), Somasifu ME-100 (solid phase reaction method synthetic mica, trademark: manufactured by Coop Chemical Co., Ltd.) and the like can be used, and these can be used alone or in combination of two or more. it can.

  The inorganic layered compound that is more preferably used in the present invention is a swellable inorganic layered compound that easily swells, opens and disperses in water. The degree of the “swelling / cleavage” property of the swellable inorganic layered compound to the solvent can be evaluated by the following “swelling / cleavage” test. The swelling property of the swellable inorganic layered compound is preferably about 5 mL or more, more preferably about 20 mL or more in the following swellability test. Specific examples of swellability include Kunipia (swelling force: 65 mL / 2 g or more), Smecton (swelling force: 60 mL / 2 g or more), DM Clean A, DMA-350, Na-Ts (swelling force: 30 mL / 2 g or more), ME-100 (trademark: manufactured by Coop Chemical Co., swelling power: 20 mL / 2 g or more), Bengel (swelling power: 38 mL / 2 g or more), and the like. On the other hand, the cleavability of the swellable inorganic layered compound is preferably about 5 mL or more, more preferably about 20 mL or more in the following cleaving test. In these cases, a solvent having a density smaller than that of the swellable inorganic layered compound is used as the solvent. As such a solvent, water is preferably used.

The swelling test will be described in detail. Slowly add 2 g of swellable inorganic layered compound to 100 mL of solvent (100 mL graduated cylinder as container). The volume of the former (swellable inorganic layered compound dispersion layer) is read from the scale of the interface between the swellable inorganic layered compound dispersion layer and the supernatant after 24 hours at 23 ° C. The larger this value, the higher the swelling property.
The cleavage test will be described in detail. Slowly add 30 g of the swellable inorganic layered compound to 1500 mL of the solvent, and using a disperser (manufactured by Asada Tekko Co., Ltd., Desper MH-L, blade diameter 52 mm, rotation speed 3100 rpm, container capacity 3 L, bottom-blade distance 28 mm) After dispersing for 90 minutes at a peripheral speed of 8.5 m / sec (23 ° C.), take 100 mL of the dispersion, place it in a graduated cylinder and let stand for 60 minutes, then read the volume of the swellable inorganic layered compound dispersion layer from the interface with the supernatant .

The swellable inorganic layered compound preferred for use in the present invention has a cation exchange capacity of 30 to 300 meq, more preferably 50 to 250 meq, particularly preferably 60 to 200 meq per 100 g. When the cation exchange capacity is less than 30 meq / 100 g, the effect of the nitrogen-containing compound is reduced and the moisture resistance is not excellent. On the other hand, if it exceeds 300 meq / 100 g, the coating tends to aggregate, which is not preferable. In general, natural and synthetic squametites having a cation exchange capacity of 85 to 130 meq / 100 g are particularly preferred in the present invention. Cation exchange capacity is generally measured by an alcohol washing method (Schollenberger method or an improved method thereof, Mitsufumi Wada "Clay Anion / Cation Exchange Capacity Measurement", Clay Science Vol. 21, No. 4, pages 160-163 (1981)). By the way. Collect 0.2 to 1.0 g of the swellable inorganic layered compound powder or about 10 to 30 ml of about 1 to 3% aqueous dispersion in a 100 ml capacity centrifuge tube. Add 1N ammonium acetate (CH ₃ COONH ₄ ) solution (pH 7) to make about 80 ml, shake well, then centrifuge and discard the supernatant (centrifuge washing). After centrifuge washing is repeated 4 times, centrifuge washing is performed 3 times with 80% ethanol aqueous solution (pH 7) in order to remove excess salt remaining in the centrifuge tube. Next, the centrifuge washing is repeated 4 times using a 10% NaCl aqueous solution, and all the supernatant of the centrifuge tube is collected to obtain an extract. NH ₄ in the extract is quantified by distillation, and the number of milligram equivalents (meq) per dry mass (100 g) of the sample is taken as the value of cation exchange capacity (CEC). The measurement is performed in an environment of 23 ° C. The measurement was performed at 7 points, and the average of 5 points excluding the maximum value and the minimum value was used as the measurement value.

  The swellable inorganic layered compound preferably has an aspect ratio of 50 to 5000. The aspect ratio (Z) is indicated by the relationship Z = L / a, where L is the average particle diameter of the swellable inorganic layered compound in water (measured by laser diffraction method. HORIBA, Ltd. LA-910, refractive index 1.3, median diameter of volume distribution 50%), and a is the thickness of the swellable inorganic layered compound. The thickness is a value obtained by observing a cross section of the moisture-proof layer by photographic observation with SEM or TEM. The average particle size is preferably 0.1 μm to 100 μm, particularly preferably 0.5 μm to 50 μm. When the average particle size is less than 0.1 μm, the aspect ratio becomes small, and it becomes difficult to arrange the moisture-proof layer in parallel to the moisture-proof surface, and the moisture-proof effect becomes insufficient. When the average particle diameter exceeds 100 μm, the swellable inorganic layered compound protrudes from the moisture-proof layer, which is not preferable.

  Among these swellable inorganic layered compounds, sodium tetrasilicon mica, sodium teniolite, lithium teniolite, sodium hectorite, lithium hectorite, saponite, and natural smectite (montmorillonite) are preferable. Among these, sodium tetrasilicon mica (manufactured by Topy Industries Co., Ltd., “DMA350”) and talc produced by the fusion synthesis method in terms of average particle diameter, aspect ratio, and crystallinity, and intercalating silicon fluoride, Swellable fluorine mica obtained by baking at 800 ° C. is particularly preferred. In addition, the inorganic layered compound used in the present invention preferably has an average particle diameter of 20 nm to 100 μm, preferably 0.1 μm to 50 μm, more preferably dispersed in water or a solvent. 1 μm to 30 μm. When the average particle size is less than 20 nm, the aspect ratio becomes small, and the effect of improving moisture resistance is small. On the other hand, if the thickness exceeds 100 μm, the pigment protrudes from the surface of the coating layer, which leads to poor appearance and reduced moisture resistance, which is not preferable.

  The average particle size of the swellable inorganic layered compound used in the present invention dispersed in water or solvent is a value measured with a particle size distribution measuring apparatus by laser diffraction applying light scattering theory when the average particle size is 0.1 μm or more. It is. For those having an average particle size of 0.1 μm or less dispersed in water or a solvent, the values are measured using a dynamic light scattering method. Further, the preferred aspect ratio of the swellable inorganic layered compound used in the present invention is 5 or more, and particularly preferably the aspect ratio is 10 or more. When the aspect ratio is less than 5, the moisture resistance is lowered because the curved path effect is small. The higher the aspect ratio, the higher the number of layers in the coating layer of the inorganic stratiform compound, and the higher the moisture-proof performance. The thickness of the inorganic layered compound is measured from a cross-sectional photograph of the moisture-proof film. Thickness of 0.1 μm or more is obtained by image analysis from an electron micrograph. Those having a thickness of less than 0.1 μm are obtained by image analysis from a transmission electron micrograph. The aspect ratio referred to in the present invention is obtained by dividing the average particle diameter dispersed in the water or solvent by the thickness obtained from the cross-sectional photograph of the moisture-proof film.

  In the present invention, the blending amount of the water-soluble polymer such as polyvinyl alcohol resin and the inorganic layered compound in the gas barrier layer is preferably 99: 1 to 50:50, more preferably 97: 3 to 60:40, in terms of mass. Particularly preferred is 95: 5 to 80:20. When the compounding amount of the inorganic stratiform compound is less than 1% by mass, the moisture proof improvement effect and the disaggregation improvement effect are reduced. When the amount of the inorganic layered compound exceeds 50% by mass, the resin that fills the space between the inorganic layered compounds is insufficient, leading to an increase in voids and pinholes, resulting in deterioration of moisture resistance.

  The gas barrier paint in the present invention is a water-based paint, but if necessary, an alcohol solvent such as ethanol or isopropyl alcohol, or a solvent such as methyl ethyl ketone or toluene may be added.

  In the present invention, a gas barrier coating is applied to a paper support to form a gas barrier layer. The coating equipment is not particularly limited, but a blade coater, bar coater, air knife coater, slit die coater, gravure coater, micro gravure coater, gate roll coater or the like is preferable. In particular, a coater that scrapes the coating surface such as a blade coater, a bar coater, an air knife coater, or a slit die coater is preferable for forming the gas barrier layer in terms of promoting the orientation of the inorganic layered compound.

  The substrate used in the present invention is not particularly limited as long as it contains plant-derived pulp as a main component, but is not limited to fine paper, medium paper, fine coated paper, coated paper, glossy paper, bleached or Preference is given to unbleached kraft paper (acidic paper or neutral paper), paperboard used for corrugated cardboard, building materials, whiteball, chipboard, and the like.

  Further, a pigment layer containing a pigment and a resin may be provided between the base material and the moisture-proof layer in order to reduce the coating suitability of the moisture-proof layer and the coating amount. Alternatively, a pigment layer containing a pigment and a resin may be provided on the surface of the substrate opposite to the gas barrier layer in order to improve printability. As the pigment, calcium carbonate, kaolin, clay, calcined clay, talc, barium sulfate and the like are preferably used. As the resin, a styrene-butadiene copolymer, an acrylic-styrene copolymer, polyvinyl alcohol, starch, or the like is preferably used. The mixing ratio of the pigment and the resin is preferably pigment / resin = 50/50 to 99/1 in terms of mass.

  The structure of the gas barrier laminate of the present invention is as follows: substrate / first gas barrier layer / second gas barrier layer, substrate / pigment layer / first gas barrier layer / second gas barrier layer, pigment layer / substrate / Examples include first gas barrier layer / second gas barrier layer, pigment layer / base material / pigment layer / first gas barrier layer / second gas barrier layer.

  Moreover, a sealant layer such as polyethylene or polypropylene is provided on the second gas barrier layer of the gas barrier laminate of the present invention to form a packaging laminate. The sealant can be laminated by a melt extrusion lamination method, a dry lamination method, or a coating method. An anchor layer may be provided in order to improve adhesion between the gas barrier layer and the sealant layer. The anchor layer is preferably a urethane-based resin or a polyester-based resin, and may contain a curing agent such as isocyanate.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the examples, “parts” and “%” indicate “parts by mass” and “% by mass” unless otherwise specified.

<Example 1>
[Preparation of polyvinyl alcohol solution (1)]
90.5 parts by mass of water, 9.5 parts by mass of ethylene-modified polyvinyl alcohol (trade name: “Exeval HR3010”, Kuraray Co., Ltd., water content of about 5%), polyoxyethylene (5 mol addition), polyoxypropylene (30 mol addition) ) Block polymer (trade name: “Pepol B-181”, manufactured by Toho Chemical Industry Co., Ltd.) 0.009 parts by mass, heated to 95 ° C. with stirring, held for 1 hour, cooled to room temperature, concentration 9 % Aqueous solution of ethylene-modified polyvinyl alcohol was obtained. In addition, no foaming was observed during the temperature raising process and during the temperature holding.

[Manufacture of gas barrier laminates]
^{On one side} of a coated paper having a basis weight of 84 g / m ² (Oji Paper Co., Ltd .: trade name “OK Top Coat”, pigment layer / base material / pigment layer, pigment layer coating amount is 15 g / m ² on one side) Into 111 parts by mass of the 9% polyvinyl alcohol solution (1) obtained by the preparation of the ethylene-modified polyvinyl alcohol solution (1), an aqueous dispersion of an inorganic layered compound (Topy Industries, NTO-5, solid content 6%) , 33.3 parts by mass of sodium tetrasilicate mica) and 5.7 parts by mass of water, and stirring to obtain a first gas barrier paint (solid content 8%, viscosity 350 mPa · s) with a solid content of 1 After coating with an air knife coater so as to be 0.5 g / m ² , it was dried to form a first gas barrier layer. Next, a 9% polyvinyl alcohol solution (1) is diluted to 5% with water to form a second gas barrier coating material, so that the solid content is 1.5 g / m ² on the first gas barrier layer. The second gas barrier layer was formed by coating and drying using an air knife coater to obtain the gas barrier laminate of the present invention.

<Example 2>
In [Preparation of ethylene-modified polyvinyl alcohol solution (1)] in Example 1, polyoxyethylene (5 mol addition) polyoxypropylene (30 mol addition) block polymer (trade name: “Pepol B-181”, Toho Chemical Industry Co., Ltd.) Instead of 0.009 parts by mass) polyoxyethylene (10 mol addition) polyoxypropylene (30 mol addition) block polymer (trade name: “Pepol B-182”, manufactured by Toho Chemical Industry Co., Ltd.) 0.009 A gas barrier laminate was obtained in the same manner as in Example 1 except that a part by mass was added.

<Example 3>
[Preparation of polyvinyl alcohol solution (2)]
90.5 parts by mass of water, 9.5 parts by mass of silicon-modified polyvinyl alcohol (trade name: “R-1130”, manufactured by Kuraray Co., Ltd., water content of about 5%), polyoxyethylene (5 mol addition) polyoxypropylene (30 mol) Addition) Block polymer (trade name: “Pepol B-181”, manufactured by Toho Chemical Industry Co., Ltd.) 0.009 parts by mass, heated to 95 ° C. with stirring, held for 1 hour, cooled to room temperature, concentration A 9% silicon-modified polyvinyl alcohol aqueous solution was obtained. In addition, no foaming was observed during the temperature raising process and during the temperature holding.

[Manufacture of gas barrier laminates]
^{On one side} of a coated paper having a basis weight of 84 g / m ² (Oji Paper Co., Ltd .: trade name “OK Top Coat”, pigment layer / base material / pigment layer, pigment layer coating amount is 15 g / m ² on one side) Into 111 parts by mass of the 9% polyvinyl alcohol solution (1) obtained by the preparation of the silicon-modified polyvinyl alcohol solution (2), an aqueous dispersion of an inorganic layered compound (NTO-5, manufactured by Topy Industries, Ltd., 6% solid content) 33.3 parts by mass of sodium tetrasilicic acid mica) and 5.7 parts by mass of water were added and stirred to obtain a first gas barrier paint (solid content 8%, viscosity 300 mPa · s) with a solid content of 1 After coating with an air knife coater so as to be 0.5 g / m ² , it was dried to form a first gas barrier layer. Next, a 9% polyvinyl alcohol solution (2) is diluted to 5% with water to obtain a second gas barrier coating material, so that the solid content is 1.5 g / m ² on the first gas barrier layer. The second gas barrier layer was formed by coating and drying using an air knife coater to obtain the gas barrier laminate of the present invention.

<Example 4>
[Manufacture of gas barrier laminates]
^{On one side} of a coated paper having a basis weight of 84 g / m ² (Oji Paper Co., Ltd .: trade name “OK Top Coat”, pigment layer / base material / pigment layer, pigment layer coating amount is 15 g / m ² on one side) The aqueous dispersion of inorganic layered compound (Topy Industries, NTO-1, solid content 2) was added to 111 parts by mass of the 9% ethylene-modified polyvinyl alcohol solution (1) obtained in the preparation of the ethylene-modified polyvinyl alcohol solution (1). 25.0 parts by weight of sodium tetrasilicate mica) and 39.0 parts by weight of water, and the first gas barrier paint (solid content 6%, viscosity 100 mPa · s) obtained by stirring is solid content. After coating with an air knife coater so as to be 2.0 g / m ² , drying was performed to form a first gas barrier layer. Next, a 9% ethylene-modified polyvinyl alcohol solution (1) is diluted to 5% with water to obtain a second gas barrier coating material, which has a solid content of 1.0 g / m ² on the first gas barrier layer. As described above, coating and drying were performed using an air knife coater to form a second gas barrier layer to obtain a gas barrier laminate.

<Example 5>
In [Preparation of ethylene-modified polyvinyl alcohol solution (1)] in Example 1, polyoxyethylene (5 mol addition) polyoxypropylene (30 mol addition) block polymer (trade name: “Pepol B-181”, Toho Chemical Industry Co., Ltd.) As a result of reducing the addition amount of 0.009 parts by mass to 0.0005 parts by mass, the defoaming effect was not sufficient and an increase in the liquid level was observed. Moreover, using this polyvinyl alcohol solution, the 1st, 2nd gas barrier layer was formed like Example 1, and the gas barrier laminated body was obtained. Although slight foaming was observed during coating, the oxygen permeability of the obtained gas barrier laminate was not a problem in practice.

<Example 6>
In [Preparation of ethylene-modified polyvinyl alcohol solution (1)] in Example 1, polyoxyethylene (5 mol addition) polyoxypropylene (30 mol addition) block polymer (trade name: “Pepol B-181”, Toho Chemical Industry Co., Ltd.) The amount of addition was increased from 0.009 parts by mass to 5.0 parts by mass, and dissolution was performed. Moreover, using this polyvinyl alcohol solution, the 1st, 2nd gas barrier layer was formed like Example 1, and the gas barrier laminated body was obtained.

<Example 7>
In [Production of Gas Barrier Laminate] in Example 1, coating was performed with an air knife coater so that the coating amount of the first gas barrier was 3.0 g / m ² in terms of solid content, followed by drying. A gas barrier laminate was obtained in the same manner as in Example 1 except that no barrier layer was formed.

<Example 8>
[Preparation of oxidized starch solution (1)]
Oxidized starch (trade name: “Oji Ace A” manufactured by Oji Starch Co., Ltd., water content: about 12%) 10.3 parts by mass, polyoxyethylene (5 mol addition) polyoxypropylene (30 mol addition) ) Block polymer (trade name: “Pepol B-181”, manufactured by Toho Chemical Industry Co., Ltd.) 0.009 parts by mass, heated to 95 ° C. with stirring, held for 1 hour, cooled to room temperature, concentration 9 % Oxidized starch aqueous solution was obtained. In addition, no foaming was observed during the temperature raising process and during the temperature holding.

[Manufacture of gas barrier laminates]
^{On one side} of a coated paper having a basis weight of 84 g / m ² (Oji Paper Co., Ltd .: trade name “OK Top Coat”, pigment layer / base material / pigment layer, pigment layer coating amount is 15 g / m ² on one side) To 111 parts by mass of the 9% polyvinyl alcohol solution (1) obtained by the preparation of the ethylene-modified polyvinyl alcohol aqueous solution (1) obtained in Example 1, an aqueous dispersion of an inorganic layered compound (NTO-5, manufactured by Topy Industries, Ltd.). The first gas barrier coating (solid content 8%, viscosity 350 mPa · s) obtained by adding 33.3 parts by weight, solid content 6%, sodium tetrasilicate mica) and 5.7 parts by weight of water and stirring Was coated with an air knife coater so as to have a solid content of 1.5 g / m ² and then dried to form a first gas barrier layer. Next, the 9% oxidized starch aqueous solution (1) obtained in the preparation of the oxidized starch solution (1) is diluted to 5% with water to obtain a second gas barrier coating material, and solidified on the first gas barrier layer. The gas barrier laminate of the present invention was obtained by coating and drying with an air knife coater so as to obtain 1.5 g / m ² in a minute to form a second gas barrier layer.

<Comparative Example 1>
In [Preparation of ethylene-modified polyvinyl alcohol solution (1)] in Example 1, polyoxyethylene (5 mol addition) polyoxypropylene (30 mol addition) block polymer (trade name: “Pepol B-181”, Toho Chemical Industry Co., Ltd.) A gas barrier laminate was obtained in the same manner as in Example 1 except that no product was added. When the polyvinyl alcohol was dissolved, the liquid level increased due to foaming during the temperature rise, and the tank was likely to overflow, so the amount of dissolution had to be limited. Further, the foaming of the paint was intense even when the first gas barrier layer and the second gas barrier layer were applied, and when a sufficient amount of application was supplied, the paint overflowed from the color pan.

The gas barrier laminates obtained in Examples and Comparative Examples were evaluated by the following methods, and the results are shown in Table 1.
[Evaluation method]
<Oxygen permeability>
On the gas barrier layer of the gas barrier laminate produced in the examples and comparative examples, an anchoring agent for lamination (manufactured by Toyo Morton, polyester-based main component polyester EL557A / polyisocyanate-based curing agent / ethyl acetate = 1.6 / 0.8 / 12.5 parts in a solid ratio) was applied so that the coating amount was 4 cc / m ² in solid form and dried at 80 ° C. for 30 seconds.
On the obtained anchor layer, polyethylene (manufactured by Nippon Polychem, LC522, low density polyethylene, MFR 3.5 g / 10 min) was melt-extruded and laminated to a thickness of 20 μm. A sample of the obtained polyethylene laminate is obtained by JIS-K-7126 B method (isobaric method) with the polyethylene lamination side as the oxygen detector side (nitrogen side) and both the oxygen side and the nitrogen side at 23 ° C. and 90% RH. It was measured under conditions (oxygen permeability measuring device: OX-TRAN100 type, manufactured by MOCON).
After setting the sample, the value after 24 hours was defined as the oxygen permeability.
The oxygen permeability is preferably 30 cc / m ² · 24 hr or less, particularly preferably 20 cc / m ² · 24 hr or less.

<Evaluation of foaming state when polyvinyl alcohol is dissolved>
○: No foaming is observed during dissolution.
Δ: Some foaming is observed, and bubbles remain on the liquid surface even after cooling.
X: Foaming vigorously during the temperature rise, and the solution is likely to overflow from the tank.

<Evaluation of foaming state during gas barrier layer coating>
○: No foaming is seen in the color pan during coating.
Δ: Gas barrier layer paint in the color pan becomes cloudy with bubbles. The fluidity is also slightly bad.
X: Foaming of the gas barrier layer paint in the color pan is intense, and the paint overflows from the color pan.

  As is apparent from Table 1, a first gas barrier layer containing a water-soluble polymer such as polyvinyl alcohol resin and an inorganic layered compound and a second gas barrier layer containing a water-soluble polymer such as polyvinyl alcohol resin as main components. In air knife coating, which is a coating method that promotes the orientation of inorganic layered compounds by adding polyoxyethylene (3 to 10 mol addition) polyoxypropylene (25 to 35 mol addition) block polymer to at least one layer of An excellent gas barrier laminate was obtained without lowering the barrier properties caused by coating defects due to foam.

  The gas barrier layer coating composition according to the present invention hardly foams, and can provide stable operability and excellent gas barrier properties even during coating preparation or coating. Moreover, since the polyoxyethylene (3-10 mol addition) polyoxypropylene (25-35 mol addition) block polymer used by this invention is a highly safe compound, the gas barrier laminated body using this is extremely practical. Useful.

Claims (9)

A gas barrier laminate in which at least one gas barrier layer containing a water-soluble polymer and an inorganic layered compound is provided on a paper support, wherein the gas barrier layer contains a polyoxyethylene polyoxypropylene block polymer. Characteristic gas barrier laminate. A first gas barrier layer containing a water-soluble polymer and an inorganic layered compound and a second gas barrier layer mainly composed of the water-soluble polymer are sequentially provided on the paper support, and the first gas barrier layer and / or the first gas barrier layer are provided. A gas barrier laminate comprising a polyoxyethylene polyoxypropylene block polymer in the gas barrier layer. The gas barrier according to claim 1 or 2, wherein the polyoxyethylene polyoxypropylene block polymer is a polyoxyethylene (3 to 10 mol addition) polyoxypropylene (25 to 35 mol addition) block polymer. Laminate. The gas-barrier laminate according to any one of claims 1 to 3, wherein the water-soluble polymer is a polyvinyl alcohol resin. 5. The polyoxyethylene polyoxypropylene block polymer is contained in an amount of 0.01 to 1.0 part by mass with respect to 100 parts by mass of the water-soluble polymer. 5. Gas barrier laminate. The gas barrier laminate according to claim 4, wherein the polyvinyl alcohol-based resin is ethylene-modified polyvinyl alcohol. The gas barrier laminate according to any one of claims 1 to 6, wherein a mass ratio of the water-soluble polymer to the inorganic stratiform compound is 99/1 to 50/50. The gas barrier laminate according to claim 3, wherein the polyoxyethylene polyoxypropylene block polymer is a polyoxyethylene (5 mol addition) polyoxypropylene (30 mol addition) block polymer. A method for producing a gas barrier laminate, wherein the polyoxyethylene polyoxypropylene block polymer is added before and / or during temperature rise when the water-soluble polymer is dissolved.