JP5286850B2 - Packaging material for liquid paper container and liquid paper container manufactured from the packaging material - Google Patents

Description

  The present invention relates to a packaging material, and more specifically, to a packaging material for a liquid paper container that prevents pinholes generated inside the liquid paper container.

  In general, a liquid paper container is formed using various laminates as packaging materials in order to ensure the storability of contents, strength as a container, gas barrier properties, and the like. As a packaging material, a basic structure is known in which a resin layer using polyethylene is provided on both sides of paper as a base material. As a packaging material used for a liquid paper container, a material having a layer structure of polyethylene layer / paper base layer / polyethylene resin / deposition film / polyethylene resin from the outside is known (for example, Patent Document 1). ).

JP-A-7-148895 (paragraphs 0027 and 0029)

  When assembling and bonding the packaging material for the above-mentioned liquid paper container, normally, hot air (hot air) is blown to the bonding position on the filling machine to melt the adhesive polyolefin-based resin, and press and heat-weld. . At that time, water evaporates from the paper and passes through the adhesive polyolefin resin on the inner surface layer of the liquid paper container, thereby generating a pinhole (a small hole reaching the paper from the inner surface of the packaging material) in the inner surface layer. There is a risk. When a pinhole is generated by heating in the packaging material of the liquid paper container, the barrier function is lowered, and there is a possibility that the content leaks or the body bulges.

  In particular, in a liquid paper container using a vapor deposition film, a pinhole tends to occur when the top portion and the bottom portion are sealed. Therefore, in the prior art, linear low density polyethylene (LLDPE) using a metallocene-based catalyst with good low-temperature sealability is used for the sealant layer. In this case, the seal can be performed at a low temperature, and the work can be performed in a temperature region where no pinhole is generated. However, since LLDPE has a low density, the slipperiness is poor, and it is necessary to add an AB agent or a slip agent, or to form a multilayer structure, which increases the manufacturing cost. In addition, LLDPE using a metallocene-based catalyst tends to wear out the cutting die blades quickly because of poor cutting performance.

On the other hand, there is also known a liquid paper container in which a laminate having a barrier layer such as a vapor deposition film using low density polyethylene (LDPE) is used as a packaging material without using LLDPE using a metallocene catalyst in a sealant layer. . In this case, since it is difficult to seal in a temperature region where no pinholes are generated, pinholes are generated by setting the resin thickness of the intermediate layer between the paper base layer and the barrier layer to be twice or more the normal thickness. It is difficult. In this method, the temperature range in which stable sealing can be performed is narrower than that of the packaging material using LLDPE using the metallocene catalyst, and management in manufacturing is difficult. Further, since the thickness of the resin increases, the paper container itself becomes hard, causing molding defects, and as a result, the manufacturing cost may increase.
Further, when an aluminum foil was used as the barrier layer, no pinhole was generated, but the aluminum foil itself was affected by the water vapor and caused bubbling and whitening.

  Therefore, an object of the present invention is to provide a packaging material having a high barrier property by preventing the generation of pinholes due to heating or bubbling and whitening of an aluminum foil.

  As a result of intensive studies by the present inventors to solve the above-mentioned problems, a laminate having a coating layer containing titanium oxide on the inner surface of the paper container is used as a packaging material. It has been found that pinholes in the layer and bubbling and whitening of the aluminum foil can be prevented.

That is, in the present invention, the outermost layer, the polyethylene layer that is the outermost layer, the paper base material layer, the coating layer containing titanium oxide, the polyethylene layer that is the intermediate layer, the barrier layer, and the polyethylene layer that is the innermost layer are laminated in this order. In the packaging material for liquid paper containers , the coating layer is formed adjacent to the paper base material layer, and the coating layer has a ratio of 10 to 30 parts by mass of the binder resin with respect to 100 parts by mass of titanium oxide. And a liquid paper container formed using the packaging material.

By adopting the above configuration, the present invention prevents water vapor generated by heating from reaching the barrier layer and the innermost polyethylene layer when assembling the liquid paper container from the packaging material. It is possible to provide a liquid paper container in which generation is suppressed. The liquid paper container in which the occurrence of such pinholes is suppressed has a high barrier property and can prevent the leakage of contents and the swelling of the body.
Moreover, since generation | occurrence | production of a pinhole can be suppressed, polyethylene-type resins other than LLDPE using said metallocene-type catalyst can also be used, and the temperature range at the time of sealing becomes wide. Moreover, the resin thickness of the intermediate layer can also be suppressed. Therefore, the manufacturing cost can be suppressed, and a packaging material having good mechanical properties such as sliding can be provided.
Furthermore, when aluminum foil is conventionally used as the barrier layer, although pinholes have not occurred, the aluminum foil itself has been affected by the water vapor, causing bubbling and whitening, and cannot function as a barrier layer. According to the invention, aluminum foil can also be used as a barrier layer.

  Moreover, the liquid paper container formed from the packaging material of the present invention has a barrier layer, thereby preventing the flavor of the contents from escaping to the outside and changing the flavor. In addition, when low-density polyethylene is used for the innermost layer, the slipperiness of the innermost layer is increased, the mechanical suitability is improved, the range of possible sealing temperatures is widened, and sealing in a wide temperature range is possible. In addition, the time and cost for creating the packaging container can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing examples of the layer structure of the packaging material of the present invention.

FIG. 1 shows a polyethylene sheet 11 that is an outermost layer, a paper base layer 12, a coat layer 13 containing titanium oxide, a polyethylene layer 14 that is an intermediate layer, a barrier layer 15, It is the figure which showed what laminated | stacked the polyethylene layer 16 which is an innermost layer.
Below, each layer of the packaging material 10 for liquid paper containers of this invention is demonstrated.

The polyethylene layer 11 which is the outermost layer mainly contains polyethylene, protects the outside of the paper base material layer 12, and is heated at the end of the packaging material 10 for liquid paper containers to become the innermost layer described later. Laminated with layer 16.
Specific examples of the polyethylene used here include low density polyethylene (LDPE), medium density polyethylene (MDPE), and linear low density polyethylene (LLDPE). Low density polyethylene is preferred from the viewpoint of sealing properties, processing suitability, and the like. As the low density polyethylene, a polymer of ethylene is preferable, and specifically, a high pressure ethylene homopolymer is suitably used.
Alternatively, linear low density polyethylene (LLDPE) which is a copolymer of ethylene and α-olefin other than ethylene such as propylene, butene, pentene, hexene, octene, 4-methylpentene-1 may be used. .
The density of the low-density polyethylene is not particularly limited as long as it is generally referred to as low-density polyethylene, but is 0.90 to 0.925 g / cm ³ , and its melt index M.I. I. Is not particularly limited, and is usually from 1 to 20, and the melting point is from 100 ° C to 120 ° C.

Although the formation method of the polyethylene layer 11 which is the outermost layer is not specifically limited, For example, it forms by carrying out extrusion coating to one side of the paper base material layer 12. FIG. As processing conditions for extrusion coating, an extrusion temperature of 280 to 330 ° C. and a line speed of 100 to 300 m / min. It is set in the range. The thickness of the polyethylene layer 11 is not particularly limited, but is usually 10 to 60 μm.
The outermost polyethylene layer 11 is a layer that becomes the outer surface of the liquid paper container, but a printing layer may be further provided thereon. In order to improve the adhesion of the printing ink used for the printing layer, it is preferable to subject the surface of the polyethylene layer 11 to surface treatment (for example, corona treatment).

Since the paper base material layer 12 is a basic material constituting the liquid paper container of the present invention, a material having formability, bending resistance, rigidity, waist, strength and the like can be used. As the paper, it is a main strength material, and it is possible to use various sized paper substrates such as a strong sized bleached or unbleached paper substrate, or pure white roll paper, kraft paper, paperboard, processed paper, and milk base paper. . The paper base layer 12 may be a stack of these papers. The paper to be used can be one having a basis weight of 80 to 600 g / m ² , preferably 100 to 450 g / m ² . The paper having a thickness of 110 to 860 μm, preferably 140 to 640 μm can be used.
For example, letters, figures, symbols, and other desired patterns can be arbitrarily formed on the paper base by a normal printing method.

The coating layer 13 containing titanium oxide was coated with a coating liquid containing titanium oxide on the paper base layer 12 and the titanium oxide particles were spread on one side of the paper base layer 12. Is.
The production method of titanium oxide is not particularly limited, such as a sulfuric acid method or a chlorine method, but a sulfuric acid method that can easily produce titanium dioxide having a small particle diameter is more preferable. Further, the crystal structure of titanium oxide is not limited to a rutile type, anatase type, bulcarte type or the like, but a rutile type having a large crystal system density and being thermally stable is more preferable.
The particle size of titanium oxide is not particularly limited, but the average particle size is preferably 10 μm or less. When the average particle diameter of titanium oxide is larger than 10 μm, the titanium oxide is not uniformly arranged in the paper base material layer 12 and a gap is generated, so that the pinhole resistance effect may be deteriorated.

  The coat layer 13 containing titanium oxide contains a binder resin in addition to titanium oxide. As this binder resin, generally used binder resins can be used. Specifically, acrylic resins, urethane resins, latex resins, and the like can be used. By using these, for example, it is possible to increase the concealability by increasing the adhesiveness with the polyethylene layer 14 as an intermediate layer and increasing the adhesion.

  The coating liquid for applying the coating layer 13 containing titanium oxide can contain titanium oxide, a binder resin, and optionally other pigments and additives in a solvent. Usually, water or alcohol (for example, isopropyl alcohol) can be used as the solvent. Examples of additives that can be used include pigment dispersants, antifoaming agents, antifoaming agents, viscosity modifiers, lubricants, water resistance agents, water retention agents, coloring materials, and printing suitability improvers.

Titanium oxide contained in the coating liquid for forming a coating layer 13 containing titanium oxide, the mixing ratio of the binder resin and solvent, based on the acid titanium 10 parts by mass to 30 parts by weight of the binder resin, a solvent 40 mass Parts to 100 parts by mass.

  Although the coating method of the coat layer 13 containing titanium oxide is not particularly limited, a conventionally known coating method can be used, specifically, gravure coating, roll coating, air knife coating, blade coating, Coating methods such as short dwell and cast coating are used.

  The thickness of the coating layer 13 containing titanium oxide is not particularly limited, but is generally 0.5 to 10 μm, preferably 2 to 8 μm, and is preferably formed uniformly on the paper base layer 12. When the thickness is less than 0.5 μm, the pinhole resistance effect may be low and insufficient. When forming thicker than 10 micrometers, the viscosity of a coating liquid becomes high, it becomes difficult to apply | coat uniformly, and manufacturing suitability may worsen. Moreover, when the viscosity adjustment which can be applied is adjusted, it is necessary to apply twice, which is not preferable.

  Other layers such as a polyethylene layer can be laminated on the paper base layer 12 using a material in which a coat layer 13 containing titanium oxide is formed in advance, and the paper base layer 12 is coated with titanium oxide. Other layers can be formed in-line by coating with a working solution.

  In order to ensure adhesion between the polyethylene layer 14 as an intermediate layer and the coating layer 13 containing titanium oxide, the surface of the coating layer 13 containing titanium oxide is subjected to surface treatment such as corona treatment, flame treatment, anchor coating treatment, and the like. Can do. Further, the surface on the side of the barrier layer 15 to be described later may be subjected to corona treatment in-line, and ozone treatment may be appropriately performed on the side of the barrier layer 15 of the polyethylene layer 14 that is an intermediate layer.

  In addition, the coat layer containing titanium oxide is usually provided for the purpose of printing base or light shielding. However, in the present invention, the coating layer 13 containing titanium oxide is provided on the inner surface of the paper container, that is, the surface on which the printing layer of the packaging material 10 for liquid paper container is not provided, and moisture generated from the paper base material layer 12 is generated. The pinhole is prevented from being generated by preventing passage through the polyethylene layer 16 which is the innermost layer.

The polyethylene layer 14, which is an intermediate layer, has a function of enhancing the adhesion between the coating layer 13 containing titanium oxide and the barrier layer 15 and a function of imparting pinhole resistance, and uses a polyethylene resin. As a polyethylene-type resin used here, the material similar to the polyethylene layer 11 which is the outermost layer can be used. In addition, methacrylic acid / ethylene copolymer (EMAA), ethylene / ethyl acrylate copolymer, ethylene / acrylic acid copolymer, ethylene / methyl methacrylate copolymer, ethylene / maleic acid copolymer, One type or two or more types of copolymers of other ethylene and other olefins or unsaturated carboxylic acids or ester compounds thereof may be used. The density of the polyethylene resin used in the polyethylene layer 14 as the intermediate layer is not particularly limited, but is 0.90 to 0.95 g / cm ³ , and its melt index M.I. I. Is not particularly limited, but is usually about 1 to 20.

  The method for forming the polyethylene layer 14 as the intermediate layer is not particularly limited, but a method such as extrusion coating can be used. Further, as described later, it may be formed simultaneously with other layers. Although the thickness of the polyethylene layer 14 which is an intermediate | middle layer is not specifically limited, Usually, it is 15-60 micrometers. In addition, since the pinhole generation | occurrence | production of the polyethylene layer 16 which is an innermost layer can be prevented with the coat layer 13 containing a titanium oxide, even if the polyethylene layer 14 which is an intermediate | middle layer is 15-30 micrometers in thickness, there exists an effect of this invention. it can. Conventionally, it has been possible to control the generation of pinholes by increasing the thickness of the polyethylene layer as the intermediate layer, but this has caused inconveniences in the formability of the paper itself, leading to an increase in manufacturing costs. According to the present invention, it is possible to make the intermediate layer thinner and to solve the conventional problems.

  The barrier layer 15 is provided between the polyethylene layer 14 which is an intermediate layer and the polyethylene layer 16 which is an innermost layer, and prevents permeation of gas (for example, oxygen and carbon dioxide) and a liquid, It is provided to retain the flavor and ensure the strength of the container. The material of the barrier layer 15 is not particularly limited as long as it has strength and gas barrier properties and can prevent deterioration of the flavor of the contents. For example, MX nylon, inorganic oxide vapor deposition film, metal vapor deposition film Aluminum foil or the like is used.

  Among MX nylons, it is preferable to use nylon MXD6. Nylon MXD6 is a crystalline nylon obtained from a polycondensation reaction of metaxylenediamine and adipic acid and having an aromatic ring in the main chain. This nylon MDX has good barrier properties due to the aromatic ring in the main chain. Further, since nylon MDX6 is a material that can directly come into contact with liquid contents such as soft drinks, it is not necessary to perform a process such as skiving on the end face of the packaging material, and the process can be simplified. Further, since nylon MDX has the same strength as nylon, it is not necessary to provide a reinforcing layer, and the manufacturing cost can be reduced.

  When using nylon MXD6, it is preferable to contain 20-100 mass% of resin which forms the barrier layer 15. When the content of nylon MXD6 is less than 20% by mass, sufficient barrier properties may not be observed. Further, when the barrier layer 15 is formed using nylon MXD6 and another resin, as other resin, aliphatic nylon, aromatic nylon, ethylene vinyl alcohol copolymer, aromatic polyamide-based nanon deposit (for example, Mitsubishi Gas Chemical Co., Ltd., Imperm 103), polyamide nanocomposites (for example, Ube Industries, Ltd., UBE NCH NYON 1022C2, 5034C2) and the like are used.

  When MX nylon is used for the barrier layer 15, the thickness is not particularly limited, but is usually 3 to 60 μm. If the thickness of the barrier layer 15 is less than 3 μm, the barrier property may be insufficient. If it exceeds 60 μm, the paper container may be hardened and the molding may be difficult.

  The inorganic oxide deposited film is obtained by depositing an inorganic oxide on a film of PET, nylon, polyolefin or the like. As the inorganic oxide, aluminum oxide, silicon oxide, magnesium oxide, or the like is used. When an inorganic oxide vapor deposition film is used for the barrier layer 15, the thickness of this layer is usually 6 to 50 μm. However, most of this thickness is occupied by a film, and the thickness of the deposited inorganic oxide film is usually 50 to 2000 ohms strong (Å), preferably 100 to 1000 Å.

  The metal vapor-deposited film is obtained by vapor-depositing a metal on a film of PET, nylon, polyolefin or the like. Aluminum or the like is used as the metal. When an inorganic oxide vapor deposition film is used for the barrier layer 15, the thickness of this layer is usually 6 to 50 μm. However, the film occupies most of this thickness, and the thickness of the deposited metal film is usually 50 to 2000 ohms strong (Å), preferably 100 to 1000 Å.

  In addition, when using an inorganic oxide or metal vapor deposition film for the barrier layer 15, a vapor deposition film will contact | connect the polyethylene layer 14 which is an intermediate | middle layer directly. At this time, the polyethylene layer 14 serves to firmly bond the paper base material layer 12 and the deposited film of the barrier layer 15.

  When an aluminum foil is used as the barrier layer 15, it is usually 6 to 20 μm. At this time, in order to further impart heat resistance, a layer using a resin such as PET or nylon may be provided as a heat-resistant layer between the barrier layer 15 and the innermost polyethylene layer 16.

  The method for forming the barrier layer 15 is not particularly limited. However, when an aluminum foil or a vapor deposition film is used for the barrier layer 15, sandwich lamination is performed by using the polyethylene layer 14 as the intermediate layer for the paper base layer 12 and the barrier layer 15. It is common to do. At that time, depending on the state of adhesion, the barrier layer 15 may be subjected to corona treatment, or the resin surface of the polyethylene layer 14 as an intermediate layer may be subjected to ozone treatment. Further, the surface of the paper base layer 12 may be subjected to corona treatment, frame treatment, anchor coating treatment, and the like.

When MX nylon is used for the barrier layer 15, the polyethylene layer 14, which is an intermediate layer, the barrier layer 15, and the polyethylene layer 16 which is an innermost layer may be formed by coextrusion coating. Alternatively, a film laminated in the order of polyethylene layer / adhesive layer / MX nylon / adhesive layer / polyethylene layer may be prepared in advance, and this film may be sandwich laminated with a polyethylene layer 14 as an intermediate layer.
At this time, the resin that can be used as the adhesive layer is not particularly limited, but generally an anhydrous maleic chain graft polymer can be used. The thickness of the adhesive layer at this time is usually 2 to 10 μm, preferably 3 to 6 μm.

  As shown in FIG. 1, the innermost polyethylene layer 16 is provided on the paper base layer 12 on the side of the coating layer 13 containing titanium oxide. The polyethylene layer 16 that is the innermost layer is heat-sealed with the polyethylene layers 16 or the polyethylene layer 11 that is the outermost layer when molding a paper container. In addition, it is a layer in direct contact with the contents. For this reason, it is preferable to use a polyethylene resin that does not contain additives such as slip agents, antiblock (AB) agents, and antioxidants (for example, additive-free low-density polyethylene).

As the polyethylene layer 16 that is the innermost layer, the same layer as the polyethylene layer 11 that is the outermost layer described above can be used. Among these, it is preferable to use low density polyethylene (LDPE) or medium density polyethylene (MDPE).
When medium density polyethylene or low density polyethylene is used for the polyethylene layer 16 which is the innermost layer, the slipping of the innermost layer is increased, the mechanical suitability is improved, and it can be manufactured at low cost. Further, by using these resins, the possible range of the sealing temperature is widened, and the time and cost for creating the packaging container can be reduced.

  When an aluminum foil is used for the barrier layer 15, it is preferable to use medium density polyethylene for the polyethylene layer 16 that is the innermost layer. In this case, sorption or the like of the contents is less likely to occur, and sensory features such as flavor of the contents are improved.

  Although the thickness of the packaging material 10 for liquid paper containers of this invention is not specifically limited, Usually, it is 150-700 micrometers. When the thickness of the polyethylene layer 14 that is an intermediate layer is 15 to 30 μm, the thickness of the packaging material 10 can be 105 to 655 μm.

Although the manufacturing method of the packaging material 10 for liquid paper containers of this invention is not restrict | limited, Usually, first, the coating liquid for forming the coating layer 13 containing a titanium oxide on the paper base material layer 12 is apply | coated and dried. (80-120 ° C). It is prepared by laminating a polyethylene layer 11 which is the outermost layer on the surface opposite to the coat layer, and a polyethylene layer 14 which is an intermediate layer, a barrier layer 15 and a polyethylene layer 16 which is the innermost layer on the coat layer side.
When MX nylon is used for the barrier layer 15, the intermediate layer 14, the barrier layer 15, and the innermost layer 16 may be formed on the coat layer 13 by coextrusion coating.

  The method for producing a liquid paper container using the packaging material 10 for a liquid paper container of the present invention is usually performed as follows. After forming the packaging material for a liquid paper container of the present invention, if necessary, a printing surface is provided, punched out, and the end surface is skived and hemmed so that the contents do not contact the end surface, and then filled Inside the apparatus, the bottom and top of the paper container are heat-sealed by hot air heating, flame heating or the like to obtain a paper container.

  The shape of the paper container of the present invention can be appropriately determined according to the application and purpose. For example, shapes such as a gable top type, a brick type, a flat top type, and a cup type are exemplified. Moreover, you may provide suitably the cap made from a polyethylene, a pull tab type opening mechanism, etc. in the spout of a paper container.

  The contents of the paper container of the present invention are not particularly limited, but for example, beverages such as milk, juice, mineral water, green tea, black tea, oolong tea, sake, shochu, edible oil, soy sauce, mirin, vinegar, solids, etc. Various liquids such as contained foods such as seasonings, non-foods such as shampoos, rinses and machine oils can be used as the contents. Since the liquid paper container of the present invention has a particularly high barrier property, it is preferably used for contents that need to prevent deterioration of flavor, for example, sake, shochu, wine, juice, coffee, etc.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Example 1
The packaging material 20 for a liquid paper container of Example 1 is specifically shown in FIG.
On one surface of a paper base material layer 22 made of a liquid paper container base paper (Polatatch) having a basis weight of 320 g / m ^2, the following coating layer coating liquid A containing titanium oxide was coated with a Bose roll. Then, it was dried at 100 ° C. The average thickness of the coating layer 23 containing titanium oxide was 5 μm.

<Coating layer coating liquid A containing titanium oxide>
Titanium oxide (average particle size 6μm) 55% by mass
Styrene butadiene resin 10% by mass
30% by weight of water
IPA 2% by mass
Other 3% by mass

On the opposite surface of the paper base layer 22 on which the coating layer 23 containing titanium oxide was formed, a low density polyethylene resin (density: 0.923 g / cm ³ , melt index MI; 3.8, melting point 109 ° C. ) Was extrusion coated (extrusion temperature 300 to 320 ° C., speed 200 m / min.) To form a polyethylene layer 21 as an outermost layer having a thickness of 17 μm. Further, on the surface of the paper base layer 22 on which the coat layer 23 is formed, in order from the coat layer 23 side, LDPE (polyethylene layer 24 as an intermediate layer) 10 μm / adhesive layer 275 μm / MX nylon (barrier layer 25 ) 5 μm / adhesive layer 28 5 μm / LDPE (the innermost polyethylene layer 26) A laminate having a layer structure of 20 μm was coextruded (extrusion temperature 290 to 320 ° C., speed 200 m / min.).
The low density polyethylene resin used for the polyethylene layer 24 as the intermediate layer has a density of 0.923 g / cm ³ , a melt index M.I. I. 3.8, melting point 109 ° C. The low-density polyethylene resin used for the innermost polyethylene layer 26 is additive-free and has a density of 0.923 g / cm ³ and a melt index M.I. I. 3.8, melting point 109 ° C.
Moreover, S6011 (made by Mitsui Gas Chemical Co., Ltd.) was used for MX nylon, and Modic M545 (adhesive polyolefin: made by Mitsubishi Chemical Corporation) was used for each adhesive layer.

(Example 2)
The packaging material 30 for a liquid paper container of Example 2 is specifically shown in FIG.
A coating layer 33 containing titanium oxide was similarly formed on the paper base layer 32 made of a liquid paper container base paper (Polatatch) having a basis weight of 400 g / m ² using the same coating liquid A as in Example 1. .

LDPE of 20 μm was extrusion laminated to the opposite side of the paper substrate layer 32 having the coating layer 33 (the outermost polyethylene layer 31) (extrusion temperature 300 to 320 ° C., speed 200 m / min.). While performing the frame treatment on the surface of the paper base material layer 32 on which the coating layer 33 is formed, the deposition surface having a thickness of 12 μm made of SiOx-PET is subjected to the in-line corona treatment, and the EMAA resin (density: 0.00). Sandwich lamination was performed with the polyethylene layer 34 which is an intermediate layer composed of 93 g / cm ³ , M.I .: 8, melting point: 99 ° C. (extrusion temperature 270 to 295 ° C., speed 150 m / min.). At this time, ozone treatment was performed on the coat layer surface and the EMAA resin surface that the EMAA resin contacts. The thickness of the polyethylene layer 34 as the intermediate layer was 20 μm. Furthermore, on the PET layer of the SiOx-PET layer (barrier layer 35), an LDPE film (thickness 40 μm) is made to face while applying a urethane anchor coating agent (AC agent), and LDPE 20 μm (37) (here, Sandwich lamination (extrusion temperature 280 to 320 ° C., speed 150 m / min.) Was performed using an LDPE film and a barrier layer 35) to prepare a packaging material 30 for a liquid paper container of Example 2.
The LDPE used here is the same as that in the first embodiment.

This packaging material 30 for liquid paper containers is, from the outside, LDPE 20 μm (31) / paper substrate 400 g / m ² (32) / coat layer containing titanium oxide (33) / EMAA 20 μm (34) / SiOx-PET 12 μm (35) / LDPE 20 μm (37) / LDPE 40 μm (36).

(Example 3)
This packaging material for a liquid paper container of the present invention was prepared in the same manner as in Example 2 except that an aluminum-deposited PET film was used instead of SiOx-PET. (Aluminum vapor-deposited PET thickness 12 μm)

Example 4
The packaging material 40 for a liquid paper container of Example 4 is specifically shown in FIG.
In this packaging material, an aluminum foil was used as the barrier layer 45.
Specifically, a film made of aluminum foil 6 μm / PET 12 μm / medium density polyethylene (MDPE) was prepared in advance by dry lamination using a two-component curable urethane adhesive (the MDPE used at this time). Density: 0.931 g / cm ³ , MI: 2, melting point: 120 ° C.).
A coat layer 43 containing titanium oxide was produced on the paper base layer 42 in the same manner as in Example 2 using the same paper base as in Example 2. LDPE was laminated on the surface of the paper base layer 42 opposite to the coat layer 43 by 20 μm extrusion lamination (extrusion temperature 300 to 320 ° C., speed 200 m / min). While the coating layer 43 is subjected to a frame treatment, the aluminum foil surface of the film prepared in advance is made to face, and EMAA resin is used (as the polyethylene layer 44 as an intermediate layer) to perform sandwich lamination (extrusion temperature of 270 to 295). C., speed 150 m / min), and a liquid paper container packaging material 40 was prepared.

This packaging material 40 for liquid paper containers is, from the outside, LDPE 20 μm (41) / paper base material 400 g / m ² (42) / coating layer 5 μm (43) containing titanium oxide / EMAA 20 μm (44) / aluminum foil 6 μm (45 ) / PET 12 μm (47) / MDPE 60 μm (46).
Here, the PET layer functions as a heat-resistant layer.

(Comparative Examples 1-4)
The packaging materials of Comparative Examples 1 to 3 were produced in the same manner as in Examples 1 to 4 except that the coat layer containing titanium oxide was not formed.

  About the packaging material of an Example and a comparative example, the generation | occurrence | production condition of a pinhole and the relationship of sealing performance were evaluated. The results are shown in Table 1.

(Evaluation method)
Using a filling machine (manufactured by DNK Corporation, model number: DR-10), each packaging material was heated to each temperature with hot air, and the occurrence of pinholes was examined. The results are shown in Table 1. It should be noted, that the occurrence of pin holes are not or less observed (specifically 1cm ² 0~1 per) the ○, that the occurrence of pinholes is observed slightly (2 to 5 per 1cm ²⁾ △, pin A sample having a large number of holes (six or more per 1 cm ² ) was evaluated as x.
In Example 4 and Comparative Example 4, since an aluminum foil was used as the barrier layer, no pinhole was generated, but the determination was made based on bubbling and whitening. ○ indicates no whitening, Δ indicates that partial whitening is observed, and × indicates that AL is entirely whitened.

  The sealing performance was obtained by using a filling machine (manufactured by DNK Co., model number: DR-10), and sealing each of the packaging materials with hot air heated to each temperature. The thing which is easy to peel off was made into (triangle | delta), and the thing which is not adhere | attached was made into x.

It is a schematic cross section of the packaging material 10 for liquid paper containers of this invention. 1 is a schematic cross-sectional view of a packaging material 20 for a liquid paper container of Example 1. FIG. 3 is a schematic cross-sectional view of a packaging material 30 for a liquid paper container of Example 2. FIG. 6 is a schematic cross-sectional view of a packaging material 40 for a liquid paper container of Example 4. FIG.

Explanation of symbols

10 Packaging materials for liquid paper containers,
DESCRIPTION OF SYMBOLS 11 Polyethylene layer which is outermost layer 12 Paper base material layer 13 Coat layer containing titanium oxide 14 Polyethylene layer which is intermediate layer 15 Barrier layer 16 Polyethylene layer which is innermost layer 20 Packaging material for liquid paper container 21 Polyethylene layer which is outermost layer DESCRIPTION OF SYMBOLS 22 Paper base material layer 23 Coat layer containing titanium oxide 24 Polyethylene layer which is intermediate layer 25 Barrier layer 26 Polyethylene layer which is innermost layer 27, 28 Adhesive layer 30 Packaging material for liquid paper container 31 Polyethylene layer which is outermost layer 32 Paper Base material layer 33 Coat layer containing titanium oxide 34 Polyethylene layer as intermediate layer 35 Barrier layer 36 Polyethylene layer as innermost layer 37 Adhesive layer 40 Packaging material for liquid paper container,
DESCRIPTION OF SYMBOLS 41 Polyethylene layer which is outermost layer 42 Paper base material layer 43 Coat layer containing titanium oxide 44 Polyethylene layer which is intermediate layer 45 Barrier layer 46 Polyethylene layer which is innermost layer 47 Heat resistant layer

Claims (6)

Packaging for liquid paper containers, in which the outermost layer, polyethylene layer, paper base layer, coat layer containing titanium oxide, intermediate layer, polyethylene layer, barrier layer, innermost layer, polyethylene layer are laminated in this order In the material ,
The coat layer is formed adjacent to the paper substrate layer;
The coating layer is a packaging material for a liquid paper container, which is formed from a coating agent in which a binder resin is blended at a ratio of 10 parts by mass to 30 parts by mass with respect to 100 parts by mass of titanium oxide.   The packaging material for liquid paper containers according to claim 1, wherein the coating layer is formed with a thickness of 0.5 to 10 μm. The packaging material for liquid paper containers according to claim 1 or 2 , wherein the binder resin is at least one selected from an acrylic resin, a urethane resin, or a latex resin. The packaging for liquid paper containers according to any one of claims 1 to 3 , wherein the barrier layer is one or more of MX nylon, an inorganic oxide vapor deposition film, a metal vapor deposition film, or an aluminum foil. material. The thickness of the intermediate layer is 15 to 30 [mu] m, the liquid-packaging cartons packaging material according to any one of claims 1-4. The liquid paper container manufactured from the packaging material for liquid paper containers of any one of Claims 1-3 .

Images