JP2016078908A - Paper container for liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a container excellent in gas barrier property, regardless of the fact that the container is a paper container for liquid produced through plural folding steps.SOLUTION: A blank of a paper container for liquid is formed of a paper substrate 11 and a gas barrier layer 12, in which the gas barrier layer is a layer including a gas barrier composite structure formed by reaction of a polyvalent metal compound and a phosphorus compound. The composite structure is a composite structure coupled by covalent bond in which, a metal atom M and a phosphorus atom are expressed by M-O-P-O-M or M-O-(P-O-P)-O-M, when a polyvalent metal atom is expressed by M. Plural phosphorus atoms P coordinates with the metal atom M as a center, and plural metal atoms M coordinates with the phosphorus atom P as a center. Therefore, the composite structure has a fine structure in which atoms are bound by covalent bond in a mesh-state, as the result, high gas barrier property is exhibited. In addition, the composite structure is excellent in resistance to bending or heat.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a container that contains a liquid content and is constructed by assembling a blank made of paper as a base material and laminated with a heat-adhesive resin layer on an inner surface and an outer surface, and has a particularly excellent gas barrier property. The present invention relates to a liquid paper container.

  It is a container configured to assemble a blank made of paper as a base material and stores a liquid content, and the blank is folded to form a square cylindrical body, and the blank is folded. Liquid paper containers formed by forming a bottom portion and a top portion at the top and bottom of a rectangular cylindrical body are well known (see Patent Documents 1 to 4).

  Such a container has, for example, an appearance as shown in FIG. The container of FIG. 1 is a perspective view of a gobel top type liquid paper container, and FIG. 2 is a plan view of a blank used for manufacturing this liquid paper container. The liquid paper container is a container body A provided with a spout B.

  As can be seen from FIG. 2, in this blank, the left side plate 1, the front plate 2, the right side plate 3 and the back plate 4 are connected via folding ruled lines a2, a3 and a4 extending in the vertical direction, respectively. Further, the left side plate 1 is connected to a body adhesive piece 5 via a folding ruled line a1. The left side plate 1, the front plate 2, the right side plate 3, the back plate 4 and the body adhesive piece 5 constitute the body of the liquid paper container.

  Then, below these left side plate 1, front plate 2, right side plate 3, back plate 4 and torso adhesive strip 5, liquid paper is fed via folding lines b1, b2, b3, b4 which are continuous in the horizontal direction. A piece of paper constituting the bottom of the container is arranged, and on these left side plate 1, front plate 2, right side plate 3, and back plate 4, folding ruled lines f1, f2, f3, which are continuous in the lateral direction, are arranged. A paper piece constituting the top of the liquid paper container is arranged via f4.

  That is, first, a triangular folding plate 1a is provided under the left side plate 1 via a folding ruled line b1, and two sides of the triangular folded plate 11a are set as folding ruled lines c1 and c2 on the left side. Surface bottom portion pieces 1b and 1c are provided. The left and right left side bottom piece 1b, 1c both extend further downward from the apex of the triangular folding plate 1a, and the left and right left side bottom piece 1b, 1c via a folding ruled line d1. Are connected to each other. The folding ruled line d1 is a line that bisects the left and right left side bottom pieces 1b and 1c with the vertex of the triangular folded plate 11a as a starting point. Moreover, the lower part of the left side bottom piece 1c located on the right side in the drawing among the left and right left side bottom pieces 1b and 1c constitutes a part 6a of the bottom adhesive piece via a folding ruled line e1.

  Next, a front bottom piece 2a is provided under the front plate 2 via a folding ruled line b2. The front bottom piece 2a is connected to the left side bottom piece 1c via a folding ruled line h1. Moreover, the lower part of the front bottom piece 2a constitutes a part 6b of the bottom adhesive piece via a folding ruled line e2.

The lower side plate 3 has the same structure as the lower side plate 1. That is, a triangular folding plate 3a is provided via a folding ruled line b3, and right side bottom pieces 3b and 3c are provided with two sides of the triangular folding plate 3a as folding ruled lines c3 and c4. Yes. The left and right right side bottom piece 3b, 3c both extend further downward from the apex of the triangular folding plate 3a, and the right and left right side via the folding ruled line d2 provided in the extending portion. The bottom surface pieces 3b and 3c are connected to each other. The folding ruled line d2 is a line that bisects the right and left right side bottom pieces 3b and 3c with the apex of the triangular folded plate 3a as a starting point. Note that the right side bottom piece 3b located on the left side in the drawing is connected to the front bottom piece 2a via a folding ruled line h2. Moreover, the lower part of the right side bottom piece 3b located on the left side in the drawing among the left and right right side bottom pieces 3b, 3c constitutes a part 6c of the bottom adhesive piece via a folding ruled line e3. For this reason, the bottom adhesive piece 6 is composed of a lower part 6a of the left side bottom piece 1c, a lower part 16b of the front side bottom piece 2a, and a lower part 16c of the right side bottom piece 13b.

  A back bottom piece 4a is provided below the back plate 4 via a folding ruled line b4. The back bottom piece 4a is connected to the right side bottom piece 3c via a folding ruled line h3.

  Next, a triangular folding plate 1d is provided on the left side plate 1 via a folding ruled line f1, and two sides of the triangular folding plate 1d are used as the folding ruled lines g1 and g2 and the left side surface. Top pieces 1e and 1f are provided. On the left and right left side top pieces 1e and 1f, left side top adhesive pieces 1g and 1h are provided via folding ruled lines i1 and i2. The left and right left side surface top adhesive pieces 1g and 1h are connected to each other via a folding ruled line j1.

  A front roof plate 2d is provided on the front plate 2 via a folding ruled line f2, and a pouring spout B with a check valve is attached to the front roof plate 2d. And the front top part adhesive piece 2g is provided on this front roof board 2d via the ruled line i3 for bending. The front roof plate 2d is connected to the left side top piece 1f via the folding ruled line k1, and the front top adhesive piece 2g is connected to the left side top adhesive piece 1h via the folding ruled line 1. doing.

  Next, the structure on the right side plate 3 is the same as that on the left side plate 1. That is, a triangular folding plate 3d is provided on the right side plate 3 via a folding ruled line f3, and two sides of the triangular folding plate 3d are used as folding ruled lines g3 and g4. Pieces 3e and 3f are provided. On the right and left right side top pieces 3e and 3f, right side top adhesive pieces 3g and 3h are provided via folding ruled lines i4 and i5. The right and left right side surface top adhesive pieces 3g and 3h are connected to each other via a folding ruled line j2. Further, of the right side top pieces 3e and 3f, the right side top piece 3e located on the left side in the drawing is connected to the front roof plate 2d via a folding ruled line k2, and the right side top adhesive piece 3g is bent. It is connected to the front top adhesive piece 2g via the ruled line l2.

  Further, a back roof plate 4d is provided on the back plate 4 via a folding ruled line f4, and a back top adhesive piece 4g is provided on the back roof plate 4d via a folding ruled line i6. Is provided. The back roof plate 4d is connected to the right side top piece 3f via a folding ruled line k3, and the back top adhesive piece 4g is connected to the right side top adhesive piece 3e via a folding ruled line l3. ing.

  As described above, the liquid paper container is assembled using this blank.

  That is, first, the folding lines a1, a2, a3, a4 in the vertical direction are folded in a mountain, and the vicinity of the end face of the body adhesive piece 5 and the vicinity of the end face of the back plate 4 are overlapped and thermally bonded, so A square cylindrical sleeve is formed.

Next, the lower part of the sleeve is crushed so that the bottom adhesive piece 6 is opposed to the lower part of the left side bottom part piece 11b, the lower part of the right side bottom part piece 3c, and the rear bottom part piece 4a. Seal.
Then, the horizontal folding ruled lines b1, b2, b3, and b4 are folded in a mountain, and the folding ruled lines c1, c2, c3, and c4 are folded in a valley to weave the triangular folding plates 1a and 3a. The front bottom piece 12a and the back bottom piece 4a are stacked on the folding plates 1a and 3a and thermally bonded to form the bottom of the liquid paper container. At this time, the left side bottom piece 1c is sandwiched between the triangular folding plate 1a and the front bottom piece 2a, and the left side bottom piece between the triangular folding plate 1a and the back bottom piece 4a. 1b is sandwiched. A right side bottom piece 3b is sandwiched between the triangular folding plate 3a and the front bottom piece 2a, and a right side bottom piece 3c is sandwiched between the triangular folding plate 3a and the back bottom piece 4a. It is.

  Next, after containing the liquid contents, the top of the container is sealed. In other words, the horizontal folding ruled lines f1, f2, f3, and f4 are folded in a mountain, and the folding ruled lines g1 and g2 are folded in a valley so that the left side top portion adhesive pieces 1g and 1h face each other. Similarly, the folding ruled lines g3 and g4 are valley-folded so that the left side top portion adhesive pieces 3g and 3h face each other. The front top adhesive piece 2g and the back top adhesive piece 4g are opposed to each other. At this time, the roof plates 2d and 4d are inclined in an oblique direction with respect to the trunk portion to form a gable-like top portion. Then, the left side top adhesive pieces 1g and 1h facing each other and the left side top adhesive pieces 3g and 3h are thermally bonded to each other, and the front top adhesive piece 2g and the back top adhesive piece 4g are overlapped on this adhesive part. The top of the container can be sealed by heat bonding. The obtained liquid paper container is shown in the perspective view of FIG.

  By the way, such a liquid paper container may require a gas barrier property depending on the type of liquid content to be stored. For example, it is a case where the liquid content which is easy to oxidize is accommodated, or a case where the liquid content containing an aroma component is accommodated.

  In such cases, blanks containing gas barrier films have been used. For example, aluminum foil. However, a liquid paper container using aluminum foil has drawbacks such that a metal detector for inspecting foreign matter cannot be used, or an excessive amount of heat is required for incineration of the container. Therefore, a blank using a vapor-deposited film on which an inorganic oxide such as silicon oxide or aluminum oxide is vapor-deposited as a gas barrier film has been recommended.

  However, in the manufacturing process of the liquid paper container, as described above, there are many folding processes. When an inorganic oxide vapor-deposited film is used, cracks are likely to occur in the vapor-deposited film in these folding steps, and the gas barrier properties deteriorate due to the occurrence of cracks.

JP 08-318929 A JP 2001-31005 A JP 2008-105712 A JP 2011-93600 A

  Therefore, an object of the present invention is to provide a container having excellent gas barrier properties despite being a liquid paper container manufactured through a large number of folding steps.

That is, the present invention is a container configured by assembling a blank made of paper as a base material and containing a liquid content, wherein the blank is bent to form a rectangular tubular body, and In a liquid paper container formed by bending the blank and forming a bottom and a top at the top and bottom of the rectangular tubular body,
The blank is provided with a gas barrier layer including a gas barrier composite structure formed by a reaction between a polyvalent metal compound and a phosphorus compound.

The liquid paper container of the present invention is formed by bending a blank having a gas barrier layer, and the gas barrier layer includes a gas barrier composite structure formed by a reaction between a polyvalent metal compound and a phosphorus compound. Is a layer. In such a composite structure, when the polyvalent metal atom is represented by M, the metal atom M and the phosphorus atom are M—O—P—O—M or M—O— (P—O—P) _n —O. A composite structure bonded by a covalent bond represented by -M. Moreover, since the metal atom M is a polyvalent metal atom, a large number of phosphorus atoms P are coordinated around the metal atom M. On the other hand, since the phosphorus atom P is also a polyvalent atom, the phosphorus atom P is centered. A number of metal atoms M coordinate. For this reason, the composite structure becomes a dense structure covalently bonded in a network shape, and as a result, exhibits a high gas barrier property. And since this composite structure is excellent in the tolerance with respect to a bending | flexion and a heat | fever, even if the blank provided with the gas barrier layer containing this composite structure is bent, a high gas barrier property can be maintained. For this reason, a liquid paper container excellent in gas barrier properties can be obtained.

It is a perspective view which shows the example of a liquid paper container. It is a top view which shows the example of a blank. 3A and 3B are cross-sectional views showing examples of the blank according to the present invention. It is sectional drawing which shows the example of the blank which concerns on a comparative example.

  The liquid paper container of the present invention is constructed by assembling a single blank whose base material is paper. For example, the container is shown in the perspective view of FIG. As described above, this container is formed by folding the blank shown in the plan view of FIG. 2 to form a rectangular tube body, and further folding this blank to form the bottom and top portions above and below the rectangular tube body. It has been done.

  The liquid paper container of the present invention is characterized by this blank layer structure. That is, the blank according to the present invention is configured to include a gas barrier layer in addition to the paper base material, and the gas barrier layer includes a specific composite structure. Moreover, it is desirable to provide a waterproof and heat-adhesive resin layer on both the inner surface and the outer surface for accommodating the liquid contents and for the convenience of assembling the container. FIG. 3A is a cross section showing a blank obtained by laminating the gas barrier layer 12 and the resin layer 13 on the inner surface side of the paper base material 11 and laminating the resin layer 14 on the outer surface side of the paper base material 11. FIG. As shown in FIG. 3B, an intermediate layer 15 may be provided between the paper substrate 11 and the gas barrier layer 12. Further, printing may be performed on the outer surface side of the paper substrate 11.

By the way, the composite structure needs to be a gas barrier composite structure formed by a reaction between a polyvalent metal compound and a phosphorus compound. The gas barrier layer containing such a gas barrier composite structure is prepared by mixing a solution or dispersion containing a polyvalent metal compound with a solution containing a phosphorus compound to form a coating solution, and applying this coating solution to the paper substrate 1a. After applying and drying to remove the solvent, these polyvalent metal compounds and phosphorus compounds can be reacted to form. When a polyvalent metal atom is represented by M, this reaction causes a bond represented by M—O—P—O—M or M—O— (P—O—P) between the metal atom M and the phosphorus atom. A bond represented by _n- OM is generated. In the formula, n arbitrarily represents an integer. As described above, since this composite structure has high gas barrier properties and excellent bending resistance and heat resistance, high gas barrier properties are maintained even when a blank including the gas barrier layer 1b including this composite structure is folded. can do.

  Any element can be used as the polyvalent metal element as long as it can react with two or more molecules of the phosphorus compound. It may be a metalloid element. For example, elements such as magnesium, calcium, zinc, aluminum, silicon, titanium, and zirconium. Among these, aluminum is desirable.

  As the compound of these metal elements, any compound can be used as long as it can form a composite structure by reacting with a phosphorus compound. Generally, it is a compound having a hydroxyl group. The metal compound may be supplied in the form of a solution dissolved in a solvent, or may be supplied in the form of a dispersion in which fine particles of the metal compound are dispersed in a solvent.

  For example, aluminum nitrate can be supplied as a metal compound in the form of an aqueous solution thereof.

  Alternatively, the metal oxide fine particles may be dispersed in water or an aqueous solvent and supplied in the form of a dispersion. Desirably, it is a dispersion of aluminum oxide fine particles. In general, metal oxide fine particles have a hydroxyl group on the surface, and the presence of this hydroxyl group reacts with the phosphorus compound to form the bond. The metal oxide fine particles can be synthesized, for example, by hydrolyzing a compound in which a hydrolyzable characteristic group is bonded to a metal atom, and condensing the hydrolyzable organism. Examples of the compound that can be used as the raw material include aluminum chloride, aluminum triethoxide, and aluminum isopropoxide. In order to improve the gas barrier properties, it is desirable that the metal oxide fine particles have an average particle size in the range of 1 to 100 nm.

  Next, as the phosphorus compound, any phosphorus compound can be used as long as it can react with a polyvalent metal compound to form the bond. Typical examples are phosphoric acid compounds and derivatives thereof. For example, phosphoric acid, polyphosphoric acid, phosphorous acid, phosphonic acid and the like. As polyphosphoric acid, pyrophosphoric acid, triphosphoric acid, or polyphosphoric acid condensed with 4 or more phosphoric acids can be used. Moreover, as a derivative | guide_body of a phosphoric acid type compound, the salt, ester (for example, trimethyl phosphate), or a halide may be sufficient, and a dehydration thing (for example, phosphorus pentoxide) and a halide can be illustrated.

  The phosphorus compound can be supplied in the form of a solution. For example, an aqueous solution using water as a solvent. It can also be supplied in the form of a solution of a hydrophilic organic solvent. For example, a lower alcohol solution.

  As described above, the solution or dispersion of the polyvalent metal compound and the solution of the phosphorus compound can be mixed to form a coating solution. Other components can also be added to this coating solution. For example, polymer compounds, metal complexes, clay compounds, crosslinking agents, plasticizers, antioxidants, ultraviolet absorbers, flame retardants, and the like. Examples of the polymer compound include polyvinyl alcohol, partially saponified polyvinyl acetate, polyhydroxyethyl (meth) acrylate, polysaccharides (eg, starch), acrylic polymers (eg, polyacrylic acid, polymethacrylic acid, Acrylic acid-methacrylic acid copolymer) and salts thereof, ethylene-vinyl alcohol copolymer, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride alternating copolymer Saponified ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, and the like.

  A coating film obtained by applying this coating solution to the paper substrate 1a, removing the solvent and drying is subjected to, for example, heat treatment to react the polyvalent metal compound and the phosphorus compound to form the bond. The gas barrier layer 1b including the gas barrier composite structure according to the present invention can be formed. The thickness of the coating film may be 0.1 μm or more. For example, it is 0.2 μm or more. Further, it may be 4.0 μm or less. Preferably it is 2.0 micrometers or less.

  Next, the heat treatment temperature is desirably 110 ° C. or higher, and more desirably 140 ° C. or higher. If the heat treatment temperature is low, the time required to produce sufficient bonds is lengthened and productivity is lowered. The heat treatment time may be 5 to 300 seconds. This heat treatment can be performed by, for example, an oven.

  Next, the heat adhesive resin layers 13 and 14 on the inner surface and the outer surface of the blank are heat-bonded to each other to form a liquid paper container in a liquid-tight manner. As the heat-adhesive resin layer, a polyethylene resin, a polypropylene resin, or the like can be used. Specific examples include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, ethylene-α-olefin copolymer and other ethylene-based resins, and homo-block / random polypropylene resins. it can.

  The heat-adhesive resin layers 13 and 14 on the inner and outer surfaces can be laminated by extruding the resin constituting the heat-adhesive resin layer onto a paper substrate in a molten state. Moreover, you may adhere | attach a paper base material and each thermoadhesive resin layer using an adhesive agent.

Example 1
This example is an example using a blank having the layer configuration of FIG. Therefore, the manufacturing process will be described later.

First, MC cup base paper (single-side coated paper, basis weight 260 g / m ² ) manufactured by Oji F-Tech Co., Ltd. was used as the paper base 11. After the coated surface was subjected to corona discharge treatment, a coating solution containing aluminum oxide fine particles and a phosphorus compound was applied and dried. The coating amount is 0.4 g / m ² (thickness is about 0.4 μm). Further, the coating method is gravure coating, and the coating plate is a diagonal plate with 150 lines / inch and a depth of 55 μm. Next, heating was performed in an oven at 140 ° C. for about 30 seconds to cause the aluminum oxide fine particles contained in the coating film to react with the phosphorus compound, thereby forming the gas barrier layer 12 including the gas barrier composite structure.

  Next, a low-density polyethylene resin was melt-extruded and coated to a thickness of 30 μm on the gas barrier layer 12 to form an inner surface side resin layer 13. Moreover, after printing on the paper base material 11, this ink film was coat | covered, the low density polyethylene resin was melt-extrusion-coated to the thickness of 20 micrometers, and it was set as the outer surface side resin layer 14.

  Next, the laminated sheet thus obtained was used as a blank, and this blank was folded to form a rectangular tube-shaped body, and then this blank was further bent to form a bottom in the rectangular tube-shaped body. The liquid paper container shown in FIG. Note that the capacity of the liquid paper container is 1000 ml, and the top thereof remains open.

  The oxygen permeability of the liquid paper container thus obtained was measured by the Mocon method and found to be 0.01 cc / pg / day.

The liquid paper container was filled with a gel that turns blue when exposed to oxygen, sealed at the top, and allowed to stand for one week to check for the presence of a portion that changes color. The gel is a mixture of agar powder with sucrose fatty acid ester, caustic soda, methylene blue, and D-glucose. As a result, it was not possible to observe the blue-colored portion including many bent portions.

(Example 2)
This example is an example using a blank having the layer configuration of FIG. Therefore, the manufacturing process will be described later.

First, milk pack paper was used. This milk pack base paper is a laminate having a three-layer structure in which a low-density polyethylene layer having a thickness of 20 μm is laminated on the front and back of a paper base 11 having a basis weight of 250 g / m ² . One of the front and back low density polyethylene layers is the outer surface side resin layer 14 and the other is the intermediate layer 15.

Then, after the surface of the intermediate layer 15 was subjected to corona discharge treatment, a coating solution containing aluminum oxide fine particles and a phosphorus compound was applied and dried. The coating amount is 0.3 g / m ² . Further, the coating method is gravure coating, and the coating plate is a hatched plate with 200 lines / inch and a depth of 30 μm. Next, it heated for about 30 seconds in 110 degreeC oven, the aluminum oxide microparticles and phosphorus compound which were contained in the coating film were made to react, and the gas barrier layer 12 containing a gas barrier composite structure was formed.

  Then, a low density polyethylene resin was melt-extruded and coated to a thickness of 30 μm on the gas barrier layer 12 to form an inner surface side resin layer 13.

  Next, using the laminated sheet thus obtained as a blank, a liquid paper container having a capacity of 1000 ml was produced in the same manner as in Example 1. The oxygen transmission rate by the Mocon method was 0.02 cc / pg / day.

  In addition, as in Example 1, after filling a gel that turns blue when exposed to oxygen, sealing, and leaving it for one week, and examining the presence or absence of a portion that changes color, the blue color including a large number of bent portions was obtained. The part discolored to was not observable.

(Comparative example)
In this example, a blank having the layer configuration of FIG. 4 is used. That is, this laminated sheet uses a vapor-deposited laminated film 17 in which a vapor-deposited film of silicon oxide is first formed on a polyester film to form a vapor-deposited film 171, and a low-density polyethylene layer is laminated on the front and back. Note that one of the front and back low density polyethylene layers is the inner surface side resin layer 13 and the other is the intermediate layer 172. And this vapor deposition laminated film 17 and the paper base material 11 are laminated | stacked through the polyethylene layer 16, and the outer surface side resin layer 14 is laminated | stacked on the opposite side (outer surface side) of the paper base material 11. . The manufacturing process will be described below.

  That is, first, low-density polyethylene was melt-extruded and coated on both surfaces of the vapor deposition film 171 to form the inner surface side resin layer 13 and the intermediate layer 172. The inner surface side resin layer 13 has a thickness of 30 μm, and the intermediate layer 172 has a thickness of 15 μm.

Next, MC cup base paper (single-side coated paper, basis weight 260 g / m ² ) manufactured by Oji F-Tech Co., Ltd. was used as the paper substrate 11. Then, low-density polyethylene was melt-extruded and coated between the paper substrate 11 and the intermediate layer 172 of the vapor-deposited laminated film 17, and the paper substrate 11 and the vapor-deposited laminated film 17 were adhered by the molten polyethylene 16. Then, the outer surface side resin layer 14 was formed by melt extrusion coating a low density polyethylene resin to a thickness of 20 μm on the outer surface side of the paper substrate 11.

  Next, using the laminated sheet thus obtained as a blank, a liquid paper container having a capacity of 1000 ml was produced in the same manner as in Example 1. The oxygen transmission rate by the Mocon method was 0.025 cc / pg / day.

  In addition, as in Example 1, after filling a gel that turns blue when exposed to oxygen and sealing, it was left to stand for one week and examined for the presence or absence of a portion that changed color. As a result, many bent portions were locally blue. Discolored. From this result, it can be inferred that a crack occurs in the deposited film of silicon oxide at the bent portion, and the oxygen barrier property is lowered due to the crack.

11: Paper base material 12: Gas barrier layer 13: Inner surface side resin layer 14: Outer surface side resin layer
15: Middle layer

Claims (1)

It is a container configured to assemble a blank made of paper as a base material and stores a liquid content, and the blank is folded to form a square cylindrical body, and the blank is folded. In a liquid paper container formed by forming a bottom and a top at the top and bottom of a rectangular tubular body,
A liquid paper container, wherein the blank includes a gas barrier layer including a gas barrier composite structure formed by a reaction between a polyvalent metal compound and a phosphorus compound.