JP2001278330A - Laminated packaging material and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the strength, production efficiency and cost performance for a barriering packaging container which is formed of a packaging material. SOLUTION: The laminated material (10) for forming the laminated packaging material for foods is composed at least of a paper matter core layer (11), a quality-keeping intermediate layer (12) laminated at the inside of the core layer and a heat-sealing innermost layer (13). The quality-keeping intermediate layer is formed of a blend polymer which is available for extrusion coating and made up by mixing a 60-95% of polymer composition A comprising nylon-MXD6 and a 5-40% of polymer composition B comprising nylon-6 or nylon-66, or a blend of nylon-6 and nylon-66, and made up by laminating directly the same by extrusion onto the core layer, and the innermost layer includes at least a polypropylene having a narrow distribution of molecular weight and also has a characteristic parameter including an average density of 0.88-0.92, a peak melting point of 150 deg.C-180 deg.C, a melt flow index of 10-40, a swelling ratio (SR) of 1.4-1.6 and a lamination thickness of 5-50 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to maintaining the quality of a core layer such as paper or paperboard, including nylon-MXD6 (condensed polymer of meta-xylene diamine and adipic acid) laminated on the inner surface of the core layer by extrusion coating. The present invention relates to a laminated packaging material comprising a layer and a heat-sealable, polypropylene-containing innermost layer having a narrow molecular weight distribution, and a method for producing the packaging material.

[0002]

BACKGROUND OF THE INVENTION Flexible packaging laminates have been used for packaging liquid foods for many years. Packaging containers for milk, juice, sake, shochu, mineral water, and other beverages are made, for example, by using a web-like packaging material in which a fibrous base material (eg, paper, etc.) / Plastic laminate is scored in a longitudinal direction. It is formed into a tube by the vertical line seal, the filling material is filled in the tube-shaped packaging material, and the horizontal line seal is applied in the transverse direction of the tube-shaped packaging material. When the packaging material is in the form of a strip, it is individually cut at regular intervals and folded along the fold line to form the final shape. The final shape is a brick (parallel hexahedron)
In addition, a polygonal prism, a hexagonal prism, an octagonal prism,
There are a 0 prism shape, a tetrahedral shape having four triangular faces, and the like. The material of the fibrous base material is often thick paper.

Further, in a gable-top (roof type) paper packaging container, a paper packaging material is cut into a predetermined shape to obtain a blank sealed vertically in the container, and the bottom of the blank is sealed in a filling machine. It is obtained by filling milk, juice or other beverage filling material from the upper opening later and sealing the upper part. The appearance design of the packaging container product is printed on the surface of these packaging materials.

[0004] Laminated packaging materials used in conventional paper packaging container products are low density polyethylene (LDPE) / printing ink layer / paper core layer (fibrous carrier layer) / LDPE /
Aluminum foil (as gas barrier layer) / LDPE /
LDPE, LDPE / printing ink layer / paper core layer / LDP
E / LDPE, printing ink layer / LDPE / paper core layer / L
DPE / LDPE, LDPE / printing ink layer / paper core layer / LDPE / aluminum foil / polyester (P
ET) and the like are known, and are still widely used at present.

[0005] In the above-mentioned packaging laminate, generally, a base paper roll of a paper core layer is carried into a printing machine, the printed paper is printed on the base paper surface, and the printed paper is rolled again, and then sent to an extrusion laminator to be extruded. Molten polyolefin (for example, L
DPE) on the base paper surface, and if there is a gas barrier layer (aluminum foil, etc.) in addition to the base paper, molten polyolefin is also extruded between the gas barrier layer and the laminate.
Manufactured with a coating. When laminating a gas barrier layer as described above or further adding another functional layer, instead of laminating all the layers at once, prepare a partial laminate (semi-material) separately. Then, these partial laminates are further laminated to obtain a final laminate.

[0006] Each layer of the packaging laminate has its own function and function. The paper or cardboard fibrous core layer assembled into the packaging container is provided with a liquid-tight plastic coating on both sides of the core layer so that the liquid-absorbing fibrous core layer is protected from penetration by moisture. To protect effectively. These laminated outer layers usually provide excellent heat sealability to the packaging material,
As mentioned above, it is made of a thermoplastic such as low density polyethylene.

[0007] Laminated packaging materials consisting solely of paper or cardboard and the thermoplastic outer layer described above, however, lack mechanical strength and are inferior in barriers to gases from the outside of the container, especially oxygen gas. When the liquid food is, for example, citrus fruit juice, and is stored at room temperature for a long time,
Oxygen barrier properties are required in addition to flavor retention properties such as fragrances and flavors. The liquid foods penetrate oxygen through the carton walls, thereby losing their nutritional value. It is common to add a gas barrier layer to the laminate material to reduce oxygen ingress into the carton and minimize degradation of nutrients such as vitamin C.

As described above, in order to maintain the quality of the contents, it is necessary to prevent the fragrance, flavor, etc. of the contents from passing through the packaging material and scattering to the outside, or to reduce the fragrance, flavor, etc. The fragrance retention properties that prevent the packaging material that comes in contact with the contents product from being absorbed or prevent the odorous substances and the like from leaking from the packaging material into the contents product and hinder the aroma and flavor, and the quality of the contents product Gas barrier properties are required for packaging materials, which prevent gas (such as oxygen gas) from penetrating the laminated material container walls of the packaging container and protect the contents.
A packaging material having sufficient scent retention and gas barrier properties is preferred.

As a gas barrier material for imparting gas barrier properties to a packaging material, for example, aluminum foil, EVOH
Materials having excellent oxygen gas barrier properties, such as (ethylene vinyl alcohol), PVOH (polyvinyl alcohol), and a deposited layer of an inorganic oxide, are known. Furthermore, from recent trends, it is desirable that the quality keeping period can be extended under refrigeration conditions of about 10 to 4 ° C. That is, 7 ° C
After storage at ４4 ° C. for about 10 to 12 weeks or longer, or after storage at about 8 ° C. for about 6 to 8 weeks, nutrition and quality of contents such as vitamin C are maintained in the packaged product (contents). It is desirable.

However, in the conventional gas barrier material,
The product contents filled in the packaging container are damaged or damaged due to some defects. Also, it is considered that it is appropriate to substitute the aluminum foil with another gas barrier material from the viewpoint of environment and recycling. Although aluminum foil is effective as a barrier material, various attempts have been made to develop practical alternatives to aluminum foil as its use raises environmental concerns. It has excellent oxygen, gas and aroma barrier properties, yet is easily disposable after use.

As an alternative to the aluminum foil, it has been proposed to use a vapor-deposited layer of an inorganic oxide as a packaging material for paper containers (JP Y 05-28190, JP
T 08-500688, JP A 06-9312
0). With such a packaging material, a paper container having gas (oxygen) barrier properties can be provided. However, the above-mentioned fragrance retention or quality retention is not enough,
Unless the vapor deposition layer of the inorganic oxide itself has mechanical strength, is maintained at the mechanical strength of the vapor deposition base layer, and the vapor deposition base layer is made of a material having multifunction, it is necessary to take an extra layer structure, In that sense, the amount of packaging material increases, the environmental load increases, and the manufacturing cost also increases.

[0012] Barrier polymers such as EVOH and PVOH as gas barrier materials in food packages, respectively, are very sensitive to moisture and when exposed to humid environments, rapidly increase their barrier properties to oxygen gas. To lose. Therefore, these barrier layers can be separated by another polymer,
For example, EVOH with a water-impermeable polyethylene layer
It is necessary to laminate so as to surround a gas barrier layer such as PVOH or PVOH. However, EVOH or P
In the production of packaging materials containing VOH and the like, it is necessary to configure the packaging material as an indispensable multilayer laminate having two protective outer layers surrounding the gas barrier layer, and this production involves high costs.

[0013] In order to impart a barrier property including a scent-retaining property to a packaging material or a film, it has been conventionally proposed that a polyamide, so-called nylon, be laminated on the packaging material or the film (JP A 51-4107).
8, JP A 58-160244, JP A 03-499
53, JP A 04-179543, JP A 05-50
562, JP A 05-261874, JP A 06-8
0873, JP A 06-305086, JP A 11-
49141). JP A 51-41078 (applicant: International Paper) is a laminate for paper containers having a laminated structure of a thermoplastic outer layer such as polyethylene / a paper base layer / a film layer such as nylon / a thermoplastic innermost layer such as polyethylene. Is disclosed. JP A 58-160
244 (Applicant: Asahi Kasei) discloses a barrier paper container in which the laminated structure is a barrier outer film containing nylon / paper / barrier inner film containing nylon. JP A 0
3-49953 (applicant: Solvay) is a container for laminating a film based on a condensation polymer of meta-xylene diamine and adipic acid (aliphatic α, ω-dicarboxylic acid), so-called nylon-MXD6, on a paper substrate. A gas barrier laminated composite is disclosed. Here, the condensed polyamide polymer of meta-xylene diamine and adipic acid is commonly referred to as "nylon-MXD6" as described above, and is a semi-crystalline polyamide, which has special properties as compared with other conventional polyamides, for example. It has excellent gas barrier properties to oxygen gas as well as high extensibility, bending strength, and tensile stress and higher glass transition temperature and lower water absorption. JP A 04-179543 (Applicant: Dai Nippon Printing) proposes a barrier composite paper container in which the laminated structure is at least a paper base layer // the above-mentioned nylon-MXD6 layer // adhesive polyolefin innermost layer. JP A 05-22
No. 9070 (Applicant: Westvaco) discloses a paperboard support layer, an amorphous polyamide and a heat sealable polyolefin innermost package laminate. The major disadvantage of this laminated laminate is that it does not have a sufficiently good gas barrier property at an economical polymer layer thickness in a package having an extended quality assurance period. Because you have to do it. JP A 05-50562 (applicant: Dai Nippon Printing) is a semi-aromatic polyamide inner peripheral layer having a laminate structure of a paper base layer // a copolymer of an aliphatic polyamide component and an aromatic polyamide component. We propose a barrier composite paper container. JP A 05-261874 (applicant: Okura Kogyo Co., Ltd.) discloses a blend / polyamide resin layer of a xylene diamine-based polyamide such as nylon-MXD6 and another polyamide such as nylon-6, a modified polyolefin adhesive layer, and a polyolefin layer. , A co-extruded multilayer packaging file has been proposed. JP A 06-
80873 (Applicant: Ube Industries) proposes a resin composition for an oxygen barrier packaging film in which a layered silicate (so-called nano-clay) is uniformly dispersed in an aliphatic polyamide resin and an aromatic polyamide resin. . The toughness and tensile properties of aliphatic polyamides and those of aromatic polyamides and nano-
The effect is to obtain a resin composition (packaging container) having both the oxygen gas barrier properties of clay. JP A 06-30
5086 (applicant: Mitsubishi Kasei) is a nylon-MXD6
Disclosed is a paper container comprising a two-layer biaxially stretched film including a layer made of a mixture of an aromatic polyamide and an aliphatic polyamide, and a paper layer. JP A 06-305086
Describes a laminate from a biaxially stretched polyamide film and a paper layer, wherein the polyamide film consists of at least two polyamide layers and at least one layer containing nylon-MXD6. . The biaxially oriented film is laminated on the paper layer by a dry lamination method using an adhesive or an extrusion lamination. Such biaxial films are pre-manufactured by different processes, such as, for example, blown film and then laminated to other layers.

The laminate obtained by such a process is as follows:
To provide adhesion between the paper layer and the polyamide layer, an adhesive and a tacky urethane or acrylic adhesive, a polyester adhesive, or an intermediate tie layer must be utilized. This in turn requires more and / or different materials in the laminate, thus resulting in higher production costs and higher environmental impact. Furthermore, the adhesion between the paper layer and the polyamide layer is probably not good in the laminate. This is because the surface of the pre-manufactured film is oxidized and / or hardened and does not easily stick to the extruded tie layer. Especially in the production of such laminates, the method is more complicated and less cost effective, as it requires an extra step to pre-produce the biaxially oriented film.

On the other hand, JP A 11-49141
(Applicant: Dai Nippon Printing Co., Ltd.) directly co-extrudes a layer made of a mixture of an aromatic polyamide and an aliphatic polyamide such as nylon-MXD6 and an innermost layer of a heat-adhesive resin such as polyolefin onto a paper base layer. A paper container laminated and manufactured is disclosed. In this publication, as to the thermoplastic resin in the innermost layer, almost all known materials are listed, and there is no suggestion or teaching of any solution to the problem or problem caused by the innermost layer material.

The polyethylene used as a laminated material in the liquid food paper packaging container field is usually low-density polyethylene (L
DPE), especially high-pressure low-density polyethylene. The low molecular weight components contained in the innermost layer of the high-pressure low-density polyethylene migrate to the contents in the paper packaging container, and the taste of the contents may change when stored for a long period of time. In addition, the ethylene-α-olefin copolymer obtained using the Ziegler catalyst has a high sealing temperature and is inferior in processability,
When a lubricant is added to improve it, the lubricant transfers to the contents and reduces the taste. Paper packaging containers using linear low density polyethylene (LLDPE) for the innermost layer have been proposed (JP A 62-78059, JP A).
60-99647). Excellent in impact strength, tear strength, low temperature brittleness, heat seal strength, hot tagging properties, etc. However, compared to LDPE, EVA and ionomers, it is said that the heat-sealing start temperature is somewhat higher, so that the converting properties are inferior.

On the other hand, a paper packaging container using an ethylene-α-olefin copolymer (so-called metallocene PE or mLLDPE) polymerized by using a metallocene catalyst in the innermost layer has been proposed (JP A). 07-1
48895, JP A 08-337237, JP A 0
9-29868, JP A 09-52299, JPA
09-76435, JP A 09-142455, JP
A 09-86537, 9-76375, etc.). This metallocene PE has good low-temperature sealing properties, good processability of the film, and good hygiene due to its narrow molecular weight distribution, and is known to be applicable to containers (International Publication WO 93/93).
No. 08221, Magazine "Plastic", Vol. 44, No. 1, 60
Page, magazine "Chemical Economics", Vol. 39, No. 9, page 48, magazine "Plastic", Vol. 44, No. 10, page 83). However, even if the metallocene PE has a low temperature sealability and a low concentration of low molecular weight components, not all metallocene PEs will have effective extrusion coating properties in the production of packaging materials, thus And does not show good performance in converting characteristics. That is, the standard metallocene P
Even if E is used, it is difficult to perform extrusion coating practically.

[0018]

SUMMARY OF THE INVENTION The present invention has been made based on the above background, and has as its object to laminate a plurality of basic layers by practically extruding a paper core layer. Accordingly, it is an object of the present invention to provide a method for producing a packaging laminate material having excellent fragrance retention and gas barrier properties, which can produce (converting) the packaging laminate material effectively (efficiently).

Another object of the present invention is to provide good sealing in a wide range of sealing temperatures from high to low temperatures, so that it is easy to fill a paper packaging container and heat seal quickly. It is an object of the present invention to provide a laminated paper packaging material having a good sealability and a good quality retention property without being affected by the temperature of the filling contents.

Further, the object of the present invention is to provide an extrusion coating (lamination), high cost performance, excellent mechanical strength of a container, a thin paper core layer, a low environmental load, and a wide range of applications. And a method for producing the same, which can be heat-sealed in a temperature environment.

Yet another object of the present invention is to produce a packaging container that is particularly well suited for storing fruit juices and the like in a chilled (refrigerated) storage environment with an extended shelf life of about 6 to 10 weeks. It is to realize packaging material for.

[0022]

These objects are achieved by the present invention. That is, the laminated packaging material of the present invention is a food comprising at least a paper core layer (11), a quality maintaining intermediate layer (12) laminated inside the core layer, and a heat sealable innermost layer (13). The packaging laminate material (10), wherein the quality-retaining intermediate layer is formed of a condensation polymer of metaxylenediamine and adipic acid (nylon-
MXD6) and nylon-6 (PA-6), nylon-66 (PA-66) or a blend of nylon-6 and nylon-66 (PA-6).
/ 66) comprising an extrusion-coatable blend polymer with 5 to 40% of the polymer component B, directly extruded and laminated to the core layer, wherein the innermost layer contains at least polypropylene having a narrow molecular weight distribution; 88 ~
Average density of 0.92, preferably 0.89 to 0.91;
A peak melting point of 150 ° C to 180 ° C, preferably 155 ° C to 165 ° C, a melt flow index of 10 to 40, preferably 10 to 30, a swelling ratio (SR) of 1.4 to 1.6, and 5 to 50 μm; Preferably 15-35μ
It has a characteristic parameter of a layer thickness of m.

In a preferred embodiment of the packaging laminate material according to the invention, the blend polymer comprises 70-80% by weight of nylon MXD6 and 30-20% by weight of nylon-MXD6.
6.

In the laminated material for packaging according to a preferred embodiment of the present invention, the quality maintaining intermediate layer and the innermost layer are substantially the same between the quality maintaining intermediate layer and the innermost layer laminated inside the paper core layer. A plurality of layers made of a material are alternately laminated directly or indirectly via an adhesive layer.

[0025] In the packaging laminate material according to a preferred embodiment of the present invention, the polymer component B comprises PA-6, PA-66 or PA-6 / 66 polyamide, and fine layered silicate uniformly dispersed in the polyamide. And a molecular complex consisting of

In a preferred embodiment of the method for producing a laminated material for packaging according to the present invention, at least a paper core layer (11), a quality-retaining intermediate layer (12) laminated inside the core layer, and a heat-sealable innermost layer. A method for producing a food packaging laminated material (10) comprising (13),

Polymer component A50 of a condensation polymer (nylon-MXD6) of meta-xylene diamine and adipic acid
~ 95%, nylon-6 (PA-6), nylon-6
6 (PA-66) or polymer components B5 to 5 of a blend of nylon-6 and nylon-66 (PA-6 / 66)
0% of the blend polymer is directly extrusion coated on the core layer to laminate the quality-retaining intermediate layer, and simultaneously extruding the blend polymer and co-extruding the following heat-sealable polymer, or Following the extrusion, the following heat-sealable polymer is extrusion-coated and the heat-sealable innermost layer (13) is laminated: containing at least polypropylene having a narrow molecular weight distribution;
Average density of 0.92, preferably 0.89 to 0.91;
A peak melting point of 150 ° C to 180 ° C, preferably 155 ° C to 165 ° C, a melt flow index of 10 to 40, preferably 10 to 30, a swelling ratio (SR) of 1.4 to 1.6, and 5 to 50 μm; Preferably 15-35μ
A heat-sealable polymer having a characteristic parameter of a layer thickness of m.

In the method for producing a laminated material for packaging according to a preferred embodiment of the present invention, the laminated material for food packaging comprises a core layer of paper or paperboard, a condensation polymer of metaxylenediamine and adipic acid (nylon-MXD6) and nylon. −
6 (PA-6) having a quality-retaining intermediate layer of a blended polymer, which is applied to one side of the core layer together with the heat-sealable innermost layer by coextrusion coating.

[0029] In a preferred embodiment of the process for producing a laminated packaging material according to the invention, the quality-retaining intermediate layer is formed by coextrusion with a heat-sealable polymer without any intermediate lamination or adhesive layer. Extrusion coated directly on the core layer (11).

In the method for producing a laminated material for packaging according to a preferred embodiment of the present invention, when the heat-sealable innermost layer (13) and the quality-retaining intermediate layer are co-extruded,
Coextrusion is preferably carried out with a thin adhesive polymer having a layer thickness of 3 to 6 μm.

In the method for producing a laminated material for packaging according to a preferred embodiment of the present invention, the surface of the core layer (11) is pretreated and activated by corona or flame treatment before extrusion coating of the quality-retaining intermediate layer. .

In a preferred embodiment of the method for producing a laminated packaging material according to the present invention, the contact surface of the extruded film is activated by corona treatment or flame treatment prior to extrusion coating of the quality-retaining intermediate layer. .

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION The paper core layer usable in the present invention is usually made of kraft pulp and is required to have excellent strength and low water absorption. The types include bleached paper (FBL), unbleached paper (UBL), bleached and unbleached laminated paper (DUPLEX), clay-coated paper and multilayer laminated paper (MB). Either may be used.

As the polyamide of the polymer component B, for example, nylon-6 (PA-6), nylon-66 (PA-
66) or a blend of nylon-6 and nylon-66 (PA-6 / 66). By blending the polyamide of polymer component B with the nylon-MXD6 of polymer component A, properties such as, for example, an extrudable coatable blend polymer that can achieve improved elongation at break and improved sealing properties. Can be customized. The elongation at break of nylon-MXD6 alone is only about 2-3%, while for standard grade PA-6 it is typically 400-600%. However, an excessively large amount of PA-6 leads to more inadequate gas barrier properties, since the gas barrier properties are exponentially diminished by the amount of PA-6. Examples of polyamides of blend component B that can be used in the present invention are nylon-
6 (PA-6), PA-66 and a mixture thereof (PA
-6/66).

In the present invention, the bunred of nylon-MXD6 and the polyamide of the polymer component B are preferably immiscible bunreds, that is, a plurality (for example, two) of different melting points determined by differential scanning calorimetry (DSC). Or Nylon-MX as a matrix that exhibits spaced peaks, ie, multiple (eg, two) melt peaks instead of a single melt peak
It is a multiple (for example, two-phase) blend having D6.
Such immiscible bunreds have the advantage of not only improved tensile strength but also further improved oxygen barrier properties.

Mechanical properties such as swelling resistance, seal strength,
In order to achieve optimal properties with respect to gas barrier properties, the proportion of nylon-MXD6 included in the bunred polymer of the quality-retaining interlayer according to the present invention is greater than 50 weight percent and less than 95 weight percent;
Preferably, it is 60-95 weight percent, most preferably 70-80 weight percent. Although blends with 80% by weight nylon-MXD6 have better oxygen barrier properties than the corresponding 60% by weight blends, the optimal balance between gas barrier properties and mechanical properties of packaging containers was tested. Can be found by When the content of nylon-MXD6 is 90% by weight or more, the quality-retaining intermediate layer becomes brittle and hard, and thus cracks and peeling are more likely to occur.

The quality-retaining intermediate layer used in the packaging laminate according to the invention can be extrusion-coated with a polymer component A of nylon-MXD6 and a polymer component B of PA-6, PA-66 or PA-6 / 66. It consists of various blend polymers. Therefore, as described above, the polymer component A
Nylon-MXD6 and polymer component B PA-6,
PA-66 or blends with PA-6 / 66 can be extrusion coated and are useful for achieving the objects of the present invention.

According to one preferred embodiment of the present invention,
The polyamide of polymer component B is a "nylon clay hybrid" (NCH), which is, for example,
It is a molecular composite comprising a polyamide such as PA-6, PA-66, PA-6 / 66, and finely dispersed fine layered silicate.

Preferably, a layered silicate having an average particle size in the range of 1 to 80 μm and not containing a particle size of 300 μm or more is contained in the quality maintaining intermediate layer in an amount of 0.1 to 10 μm.
% By weight, and the layered silicate is substantially uniformly dispersed with an interlayer distance of 50 Å or more. In this embodiment, the fine silicate layer refers to, for example, one unit of a substance having a side of 0.002 to 1 μm and a thickness of 6 to 20 °. The interlayer distance of the layered silicate refers to the distance between the centers of gravity of the plate of the layered silicate. When the layered silicate is uniformly dispersed, when the layered silicate is dispersed in the polyamide, 50% or more of the layered silicate is separated into individual pieces without forming a lump, and the phyllosilicate is dispersed in parallel and / or randomly.
It refers to a state in which the particles are dispersed in a molecular state with an interlayer distance of not less than 00 °, more preferably 70% or more of the layered silicate is in such a state.

For example, NCH is prepared in a polymerization process by diffusing and polymerizing clay minerals in monomers, which process has a very fine structure and silicates well dispersed in a nylon polymer. Generate platelets. This therefore leads to an improved oxygen barrier and excellent mechanical properties. Such polyamides are described, for example, in the Journal of Applied Polymer Science,
Vol. 49, 1259-1264 (1993) "and" Vol.5
5, 119-123 (1995) ".
The advantage of having PA-6 is its low price,
NCH based on PA-6, PA-6 or PA-6 / 66
Has the advantage of providing significantly better oxygen gas barrier properties than its individual parent polymer. In addition, NC
H has about 2 times better moisture barrier properties than pure PA-6. NCH suitable for the blend polymer of the present invention
An example of a product based on PA-6 is commercially available (for example, Grade 1022 CM manufactured by Ube Industries, Ltd.).
1).

As a raw material of such a layered silicate, a layered phyllosilicate mineral composed of a layer of magnesium silicate or aluminum silicate can be exemplified. The amount of the layered silicate is preferably 0.05 to 15% by weight, more preferably 0.1 to 10% by weight, based on the polymer. If the amount of the layered silicate is less than 0.05% by weight, the effect of improving oxygen barrier properties, durability against stress, fragrance retention and quality retention is low, which is not preferable. Thus, for example, nylon-MXD6 can be converted to an NC based on PA-6.
By mixing with H, not only mechanical properties but also optimal gas barrier properties are obtained. In the use of pure PA-6, the proportion of nylon-MXD6, which is considerably more expensive, can be reduced without losing gas barrier properties in the same range. At the same time, when molded, folded and provided with a uniform and gas-tight barrier layer, a blend is obtained which has a considerably higher elongation at break and thus a greater resistance to crack formation. For example, a mixture of 75% by weight nylon-MXD6 and 25% by weight NCH-PA6 has an elongation at break of 200% or more.

In a preferred embodiment of the present invention, Na,
Metal ions excluding K, Li and Ca (eg, Ag, Z
A layered silicate (clay mineral) having a metal ion selected from n, Co, Cd, and Cu) or a metal compound thereof between layers can be used. This layered silicate itself, Pseudomonas aeruginosa,
It has excellent antibacterial properties against various microorganisms such as Escherichia coli and Staphylococcus aureus. Therefore, this antibacterial property is also imparted to the packaging laminated material containing the layered silicate. In this method for producing an antibacterial layered silicate, for example, a water-swellable clay mineral is converted to a water-soluble salt of a metal selected from Ag, Zn, Co, Cd, and Cu, and the organic solvent such as water, for example, methanol or acetone. The resulting precipitate is separated, washed, and dried to obtain an antimicrobial layered silicate containing metal ions. Alternatively,
An antimicrobial layered silicate having a metal hydroxide can be obtained from a precipitate obtained by dropping an alkali solution into the above dispersion.

Furthermore, the use of NCH for the polymer component B of the bunred polymer containing nylon-MXD6 reduces the effect of "bulging" of the container. "Swelling" refers to the phenomenon in which the walls of a packaging container bulge out of a vertical plane between the corners of the packaging container. The improved resistance to blistering using NCH is probably due to a partial contribution from the NCH material itself to the stiffness properties. For example, the tensile tensile stress of NCH-PA6 is about 830-8
80N / mm2, while for PA-6 alone,
It was only about 580-600 N / mm2. In addition, NC
The moisture barrier property of H is about twice as good as that of PA6 alone. Reducing the effects of blisters is of great importance since the blistered appearance of the packaging container gives the consumer a bad impression.

According to a preferred embodiment of the production method according to the present invention, it is possible to provide a packaging laminate which is well adapted to the production of a packaging container having an improved seal, and at the same time, has a further improved gas barrier property and a more cost-effective environmental load. The present invention provides a method for producing a packaging laminate having a small amount of water. This is achieved by laminating the quality-retaining intermediate layer directly onto the paper or paperboard core layer by coextrusion coating without any interfacial tacky or adhesive polymer layers. By eliminating the need for an adhesive layer at the interface, the adhesive material is saved, and
An economical laminated product is provided from the viewpoint of reducing environmental resources, facilitating recycling, and reducing costs.

As used herein, "extrusion coating" refers to the simultaneous application and extrusion of a layer of extrudable molten plastic onto a substrate, between the web of substrate layer and the pre-fabricated film layer. It differs from so-called "extrusion lamination", i.e., lamination of a preformed film onto a substrate, by forming a laminate of the substrate layer / adhesive layer / film layer by extrusion of the adhesive layer of molten plastic. For example, a nylon-MXD6-containing quality-retaining intermediate layer coated by coextrusion on a paper core layer,
The gas barrier properties of the laminate by co-extrusion coating with a three-layer structure of an adhesive layer and a heat-sealable innermost layer are improved by about 30-40%.

It is possible to co-extrude the three-layer structure into the paper core layer in one step or to co-extrude the five-layer structure on paperboard (paper core layer). Nylon-MXD6
The gas-barrier quality-preserving interlayer, which is composed of a blend of PA-6 and PA-6, or NCH, adheres very well directly to the paper or paperboard core layer even at high line speeds, indicating that Required for the production of cost-effective laminates. In this regard, it is not self-evident that the polymer is laminated by extrusion coating directly on the paperboard (paper core layer), since different polyamides have different properties. P
A-6 is usually well bonded to paper, cardboard, and paperboard, whereas amorphous polyamide does not. Good bonding means that the plastic layer bonds and adheres to the paperboard with greater strength than cohesion into the paperboard itself.
Thus, the destruction that appears in the peel test occurs in the paperboard layer, not between the layers. This can be observed in the phenomenon that the "peeled off" plastic layer surface is covered by paper fibers. Similarly, a layer of NCH or a mixture of PA-6 and NCH does not bond or adhere to paperboard,
Nylon-MXD6 adheres to a certain range. However, the bond between nylon-MXD6 and paper is weak. Nylon-MXD
The six layers themselves are brittle and do not bend, and when the laminate is bent or twisted, peels off and cracks from the paperboard.

Compared with extrusion lamination in which a quality-retaining intermediate layer is laminated on a core layer via an adhesive layer of polyethylene or the like, an oxygen gas barrier property is about 30- It has improved by 40 percent. This may be because direct application / lamination promoted moisture equalization between the core layer and the quality maintaining interlayer. When the quality-retaining intermediate layer is in direct contact with the paper or paperboard layer, moisture from the contents of the packaging container that has penetrated the quality-retaining intermediate layer is dispersed in the core layer and the quality-retaining intermediate layer. Conceivable. One of the consequences is that the proportion of water remaining in the quality-retaining intermediate layer is kept low, so that the gas barrier properties are in this case well retained by the quality-retaining intermediate layer.

This increase in oxygen barrier properties does not generally apply to all polyamides. It is unique to Nylon-MXD6 only, probably due to the fact that the gas barrier properties of Nylon-MXD6 are reduced at high relative humidity, as is usually the case when packaging liquid food products. The quality-retaining intermediate layer can, of course, be applied to any desired thickness, but is particularly suitable for packaging containers intended to extend shelf life, especially for fruit juices. According to a preferred embodiment, the quality-retaining intermediate layer comprises approximately 3 to 3
0 g / m2, more preferably 4 to 12 g / m2, most preferably 5 to 8 g / m2, is applied to the core layer. The reason for this is that, when applied and laminated at an application amount of less than 5 g / m2, the barrier properties become uncertain, and at an application amount of 8 g / m2 or more, the cost of the packaged laminate becomes significantly lower. .

On the side of the quality-retaining intermediate layer opposite to the core layer, a heat-sealable innermost layer (13) is directly or in contact with the quality-retaining intermediate layer and the heatsealable innermost layer (13).
It can be joined and laminated with the quality-retaining intermediate layer by an adhesive polymer layer laminated between them. In the present invention, the material of the heat sealable innermost layer contains at least polypropylene having a narrow molecular weight distribution.
Average density of 88 to 0.92, preferably 0.89 to 0.91, 150 to 180 ° C, preferably 155 to 16
5 ° C. peak melting point, 10-40, preferably 10-30
Melt flow index, swelling ratio (SR) of 1.4 to 1.6 and 5 to 50 μm, preferably 15 to
It has characteristic parameters of a layer thickness of 35 μm.

Examples of such a polypropylene include a polypropylene having a narrow molecular weight distribution polymerized using a metallocene catalyst, or a blend polymer containing at least the polypropylene. The metallocene catalyst is, for example, a catalyst formed by a combination of a metallocene complex and alumoxane, such as a catalyst formed by a combination of zirconocene dichloride and methylalumoxane. The metallocene catalyst has a non-uniform active site and is called a multi-site catalyst, whereas the existing catalyst is called a single-site catalyst because the active site is uniform. Examples of the α-olefin which is a comonomer copolymerized with propylene include butene-1, hexene-
1,4-methylpentene-1 and octene-1 are listed. These α-olefins may be used alone or as a mixture of two or more. In the present invention, a resin other than the metallocene-catalyzed resin can be used as long as the above-mentioned characteristic parameters are exhibited. In addition, since it is difficult to obtain the above characteristic parameters using polypropylene alone, other polymer components can be blended. Here, the “other polymer” refers to, for example, linear low-density polyethylene (LLDPE), medium-density polyethylene, polyethylene, polypropylene, ethylene having excellent resistance to contents (oil resistance, acid resistance, penetration resistance, etc.). It is a thermoplastic resin such as a polyolefin-based resin such as a copolymer or a polyester resin, and a low-density polyethylene (LDPE) that has been conventionally used.

In the present invention, the polymer of the innermost sealing layer has a swelling ratio (Swell) of 1.4 to 1.6.
ingRatio, SR). Explaining the above parameters more specifically, the “swelling / swelling”
Immediately after the extrudate exits the die orifice, the cross-sectional area increases, indicating a phenomenon in which the volume of the extrudate increases as a whole,
The swelling ratio in the present invention refers to the transverse dimension of the extrudate exiting from the die, that is, the expansion rate of the diameter, under the same conditions as the measurement conditions in the JIS test method for measuring the melt flow rate (MFR).

In the present invention, the polymer of the innermost layer of the sealing property is 150 ° C. to 180 ° C., preferably 155 ° C. to 1 ° C.
It has a peak melting point of 65 ° C. To explain the above parameters more specifically, this is the peak melting point by differential scanning calorimetry. For example, in the case of a polypropylene obtained by polymerization with a metallocene catalyst and a polypropylene obtained by polymerization with a multisite catalyst, a narrow molecular weight distribution (Mw / Mn ≦ 3) which is a characteristic of polypropylene polymerized with a metallocene catalyst. Or a polymer having a narrow composition distribution and having a well-defined molecular structure. The physical properties of the polymer are excellent in tensile strength, impact strength, tear strength, and low-temperature sealability, and the entanglement of molecules is increased. Therefore, the impurity sealing property can be improved.

Further, since the extrusion coating property is good, the concentration of additives such as a lubricant can be reduced, so that the obstacle to the sealing property is reduced and the sealing property can be maximized. The effect of the agent on the taste and ingredients of the contents is small and the sealing property is excellent, so that the protection of the contents is not impaired.

The adhesive polymer layer laminated between the quality maintaining intermediate layer and the heat sealable innermost layer may be, for example, polyethylene (including, for example, metallocene PE), ethylene-α-olefin copolymer, polypropylene , A copolymer of ethylene and an unsaturated carboxylic acid such as polybutene, polyisobutene, polyisobutylene, polybutadiene, polyisoprene, an ethylene-methacrylic acid copolymer, or an ethylene-acrylic acid copolymer, or a carboxylic acid obtained by modifying them Acid-modified polyolefin-based resins such as group-modified, polyolefin grafted with maleic anhydride, ethylene-ethyl acrylate copolymer, ethylene-vinyl methacrylate copolymer, an ionomer (IO) in which the molecules are cross-linked with metal ions, Ethylene-vinyl acetate copolymer (EVA ), Etc., these film forming layers can be laminated as an adhesive layer. The thickness of the layer is suitably about 3 to 50 μm, preferably about 3 to 6 μm, and preferably, the adhesive layer is a 3 μm to 6 μm thick EV.
A or IO. Alternatively, a blend of the adhesive polymer and PE can be utilized for the adhesion.

In a preferred embodiment of the laminate material for packaging according to the present invention, as the outermost layer of the laminate material for packaging, the thermoplastic material laminated on the outer surface of the packaging material includes, for example, polyethylene, polypropylene, ethylene copolymer and the like. A low-density polyethylene (LLDPE), which has excellent resistance to contents (oil resistance, acid resistance, penetration resistance, etc.) in addition to the conventionally used low-density polyethylene (LDPE) And coextruded resins / films containing metallocene-catalyzed linear low-density polyethylene or metallocene-catalyzed polypropylene in addition to medium-density polyethylene and polyethylene. Preferably, it is lamination by extrusion coating.

The purpose of the outermost layer and the innermost layer is, on the one hand, to protect the packaging material from penetration of moisture from inside and outside due to the moisture of the liquid food and external moisture, and, on the other hand,
It is to secure an important function that enables sealing by conventional heat sealing. As a result, the plastics of the outermost layer and the innermost layer are joined and joined by surface melting at the mutually facing layers under heating and pressing. Heat sealing achieves a mechanically strong and liquid-tight sealing joint during molding from packaging material into packaging containers. In order to achieve a good seal, the innermost
~ 35 g / m2, preferably approximately 25-30 g / m
2. Also, the outermost polyolefin layer is approximately 12
-20 g / m2, preferably 15-20 g / m2.

The outermost polyolefin layer facing outwards in the finished packaging can be provided with decoration and / or information by suitable printing to identify the filled product. That is, an ink layer by printing can be laminated on the outer surface of the laminated outermost layer that has not yet been laminated and on the outer surface of the outermost layer. Examples of the ink include a water-based or oil-based ink for flexographic printing, an oil-based ink for gravure printing, and a curable ink for offset printing.

Another preferred embodiment of the present invention, namely,
Between the quality-retaining intermediate layer and the thin innermost layer laminated inside the paper core layer, a plurality of layers made of substantially the same material as the quality-retaining intermediate layer and the innermost layer are directly or via an adhesive layer. Indirectly, in the mode of alternately laminating, together with good aroma flavor retention characteristics (so-called non-scalping characteristics),
A packaging laminate having high sealing properties can be provided. Nylon-MXD6-containing blended polymers have excellent "fragrance barrier" properties, ie, so-called non-scalping
It has barrier properties against vitamin C, aroma and flavor substances.

[0059] The packaging laminate of the preferred embodiment has a first barrier quality retaining interlayer and a second or even more barrier layers located inside the paperboard substrate (core layer). Although certain flavors and aroma substances from the filled product move to the relatively thin product contact layer of the packaging material, the barrier layer made of the blend polymer containing nylon-MXD6 moves deeper or further outward. To prevent migration and to have a thin product contact layer,
Leakage of aroma and flavor inhibitors such as impurities and low molecular monomers into internal products can be minimized. In this preferred packaging laminate, the innermost heat-sealable layer is quite thin, but no sealing failure occurs when the laminated packaging material is molded and sealed in a packaging container.
This is because, in addition to the heat sealable innermost layer, a heat sealable layer is further laminated, so that in sealing, the barrier layer inside the thin product contact layer is easily melt-penetrated,
This is because the heat-sealable layer is also melted and provided for heat sealing together with the melted heat-sealable innermost layer.

In the method of manufacturing a packaging laminate according to the invention, the laminated packaging material of the invention is preferably manufactured by one co-extrusion process, in which all polymer layers inside the core layer are co-extruded. To the core. In a preferred embodiment of the invention, a heat-sealable polymer is coated on the outside of the paper core layer, before or after the coextrusion step, on the side of the core layer. An important advantage of coextrusion is that the heat of the molten polymer is well preserved in the multilayer extruded film (due to the so-called "thermal inertia") until the extruded coated extruded molten film contacts the substrate, and thus In the material,
Another advantage is that it contributes to improved adhesion, which saves the extrusion process step, thus providing more time saving and cost effective steps. Immediately before or simultaneously with extrusion coating, the surface of the extruded film and / or the surface of the paperboard substrate is treated with corona, flame, or ozone to obtain sufficient adhesion between the multilayer coextruded film and the paperboard substrate. Can be activated by the pretreatment of

[0061]

EXAMPLES The present invention will be specifically described with reference to the following examples. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The cross-sectional view referenced in FIG. 1 shows a preferred laminated packaging material 10 according to the present invention. The packaging material 10 includes a core layer 11 of paper or paperboard that is rigid in shape but foldable. On the inner surface of the core layer 11, a polymer component A of nylon-MXD6, PA-6, PA-6
6. Laminated with a quality-retaining intermediate layer 12 of an extrusion-coatable blend polymer of polymer component B of PA-6 / 66. The content of nylon-MXD6 in the polyamide blend is preferably between 60 and 60% of the blend.
The coating weight of the polyamide blend of the quality-retaining intermediate layer, which is 95% by weight, most preferably 70-80% by weight, is preferably 5 to 10 g / m2.

The quality-retaining intermediate layer 12 made of the extrusion-coatable blended polymer according to the invention proved to adhere very well to the core layer 11 of paper or paperboard. The coating of the quality-preserving intermediate layer 12 directly on the core layer 11 is about 30-40% compared to the case where the quality-preserving intermediate layer is laminated on the paper core layer through the intermediate layer of polyethylene. It was also proved that the oxygen gas barrier property was improved. A heat sealable innermost layer 13 is laminated on the side surface of the quality maintaining intermediate layer 12 opposite to the core layer 11. On the other hand, the quality maintaining mid layer 12
On the side face of the core layer 11 on the opposite side, a layer 14 of a sealing polymer is laminated. The heat sealable innermost layer 13 is
Preferably, the coating amount is small. The sealing polymer layer 14 is LDPE or m-PE, or a blend of these two polymers, and is used, for example, at a coating amount of 15 g / m 2.

The cross-sectional view referenced in FIG. 2, like FIG. 1, shows a preferred laminated packaging material 10 according to the present invention.
The packaging material 10 also includes a paper core layer 11. On the inner side of the core layer 11 is laminated a quality-retaining intermediate layer 12 of an extrusion-coatable blended polymer according to the present invention. On the side surface of the quality maintaining intermediate layer 12 opposite to the core layer 11, an innermost heat-sealable layer 13 is laminated via an adhesive layer 15. On the other hand, the quality maintaining mid layer 12
On the side face of the core layer 11 on the opposite side, a layer 14 of a sealing polymer is laminated. The adhesive layer 15 joining the innermost sealable layer 13 and the intermediate layer 12 with quality retention is made of, for example, polyethylene graft-modified with maleic anhydride, and is used at a coating amount of about 3 to 6 g / m2.

The cross sectional views referred to in FIG. 3 are shown in FIGS.
7 shows a preferred laminated packaging material 10 according to the present invention. The packaging material 10 also includes a paper core layer 11.
On the inner surface of the core layer 11, a quality-preserving intermediate layer 1 made of an extrusion-coatable blended polymer according to the invention.
2a are stacked. On the side surface of the quality maintaining intermediate layer 12a opposite to the core layer 11, intermediate plural layers 12b and 13 are provided.
a, 15a, b, heat-sealable innermost layer 13b
Are laminated. On the other hand, a sealing polymer layer 14 is laminated on the side surface of the core layer 11 opposite to the quality maintaining intermediate layer 12.

In the embodiment shown in FIG. 3, a heat-sealable inner layer 13b of the same material as the heat-sealable inner layer is provided between the heat-sealable inner layer 13b and the quality maintaining intermediate layer 12a.
And a second quality maintaining intermediate layer 12b of the same material as the quality maintaining intermediate layer 12a are laminated via adhesive layers 15a and 15b, respectively. The innermost layer 13b should be thin to prevent too much of the aroma and flavoring substances from penetrating (absorbing) from the packaging product into the packaging material. Preferably, this layer is used at a coverage of about 6 to 12 g / m2, preferably up to 10 g / m2 and most preferably at a coverage of 6 to 9 g / m2.

The advantages of the laminated packaging material shown in FIG. 3 are as follows. Gas and Aroma Barrier Quality Retaining Middle Layer 1
2a, together with the barrier quality retaining intermediate layer 12 in the laminate
b prevents the transfer of aroma and flavoring substances from the contents product to the packaging material. Therefore, their thickness can be made sufficiently thin. In addition, the heat sealing innermost layer 13b
In addition, the heat-sealable innermost layer 13b can compensate for the total amount of the heat-sealable polymer lacking in the innermost layer 13b, and can reduce the thickness of the heat-sealable innermost layer 13b which is a product contact layer. Impurities and low molecular monomers can be transferred from the layer to the content product, and the aroma and flavor of the content product can be maintained.

Hereinafter, a method for producing a laminated packaging material according to the present invention will be described. FIG. 4 is a schematic diagram schematically showing a method of manufacturing the laminated packaging material shown in FIG. Paperboard core layer 1
1 passes through the surface activation station 20,
Here the surface is corona and / or flame treated,
It is preferably activated by flame treatment. The quality-retaining intermediate layer 12 is extruded by forming a film from a supply die 22a, and the still hot melted film is fed through a nip roll with the paperboard web, and
The bonding is performed from the polymer quality holding intermediate layer 12 by pressure and heat. It is important that the extruded polymer be sufficiently warm until contact with the paperboard substrate. The polymer of the innermost layer 13 is then extruded by creating a film from the supply die 22b, and the still hot melted film is fed through a nip roll with the laminated paperboard web and is exposed to pressure and heat to produce the polymer innermost layer. 13 are joined. Outermost layer of polyolefin 1
4 can be applied by extrusion coating on the side of the core layer of the paperboard web during, before or after the extrusion coating process.

FIG. 5 is a schematic diagram schematically showing a method of manufacturing the laminated packaging material shown in FIG. The web of paperboard substrate core layer 11 passes through a surface activation station 20, where the surface is activated by corona and / or flame treatment, preferably by flame treatment. Layers 12, 13, and 14 are co-extruded in the above order by producing a film having three layers at feed block 23, where the co-extruded film passes through the air gap between the die and the paperboard substrate to form a die. Supplied through. The surface of layer 12, which is directed to the paperboard surface, is preferably subjected to an ozone treatment 21 in an air gap to activate it. The co-extruded, still hot-melted multilayer film is fed through a nip roll with a paperboard web and laminated by pressure and heat. It is desirable that the film be sufficiently warm until it comes into contact with the paperboard substrate. The polyolefin outermost layer 14 can be applied by extrusion coating on the side of the core layer of the paperboard web during, before or after the extrusion coating process.

FIG. 6 is a schematic diagram schematically showing a method of manufacturing the laminated packaging material shown in FIG. It is possible to realize not only the three-layer structure described in FIG. 5 but also a six-layer laminated structure inside the core layer 11 without departing from the scope of the present invention. That is, as shown in FIG. 6, the web of paperboard substrate core layer 11 passes through a surface activation station 20a where the surface is activated by corona and / or flame treatment, preferably by flame treatment. Layer 12a,
13a and 15a are co-extruded by producing a three-layer film in a supply block 23a, the co-extruded film being fed through a die through an air gap between the die and the paperboard substrate. The surface of the layer 12a, which is led to the paperboard surface, is preferably subjected to an ozone treatment 21a in an air gap to activate it. The co-extruded, still hot-melted multilayer film is fed through a nip roll with a paperboard web and laminated by pressure and heat.

Subsequently, the layers 12b, 13b and 1
5b is coextruded as a three-layer film in a supply block 23b, the coextruded film being fed through the die through an air gap between the die and the paperboard substrate. The surface of the layer 12b guided to the paperboard surface is subjected to an ozone treatment 21b in an air gap to be activated. The co-extruded, still hot-melted multilayer film is fed through a nip roll with a paperboard web and laminated by pressure and heat. The polyolefin outermost layer 14 can be applied by extrusion coating on the side of the core layer of the paperboard web during, before or after the extrusion coating process.

In the field of liquid food filling which embodies the present invention, a continuous paper packaging material, which is a laminated packaging material of the present invention, is formed into a tube in the longitudinal direction, and fruit juice, tea, and liquid milk are contained in the tube-shaped packaging material. A brick-shaped paper packaging container obtained by filling a filling material such as a product, applying a horizontal line seal at predetermined intervals in the transverse direction of the tubular packaging material, and cutting the packaging material along the horizontal line sealing portion, By cutting the paper packaging material into a predetermined shape, obtaining a blank sealed in the vertical direction of the container, sealing the bottom of the blank, filling the filling of the liquid product from the upper opening, and sealing the upper portion, the obtained blank is obtained. It can also be used as a gable-top (roof type) paper packaging container.

The above-mentioned examples are merely examples of the packaging container according to the present invention, and the present invention is not limited by these examples. Furthermore, the paper packaging container obtained from the packaging material according to the present invention can be assembled into a processed paper container (a container of one-piece type, two-piece type, three-piece type, etc.), a composite can, an insert molded container, a double container, and the like. . In this case, the packaging material is punched as shown in the developed view of the composite paper packaging container, processed into a ruled line, and then folded along the ruled line and sealed to form various types of paper packaging containers. At this time, as a sealing method, there are a heat seal, a frame seal, a hot air seal, an ultrasonic seal, a high frequency seal and the like. In addition, in a filling machine, these laminates are supplied in a roll shape, a sleeve shape or a cup shape, and after filling the contents,
The paper packaging container is sealed by using the various sealing methods described above. The packaging container according to the present invention is, for example, milk, lactic acid bacteria drink, liquid soup, fruit juice drink, barley tea, green tea,
Liquid products such as Woolong tea, alcoholic beverages, seasonings, pharmaceuticals, cosmetics, paints, adhesives, inks, developers, etching solutions, etc. can be applied to filling and packaging,
Preferably, it is a liquid food.

The present invention will be specifically described with reference to the following specific examples. <Specific Example 1> Low density polyethylene (density =
0.920 g / cm3, MI = 5.1) with a thickness of 20 μm
Extrusion temperature 330 on paper base material (basis weight = 320 g / m2)
Extrusion coating at 0 ° C. and lamination of the outer thermoplastic material layer, followed by the production equipment shown in FIG.
The inside back surface of the paper base material is activated by the flame treatment of the surface activation treatment station 20. Downstream of the surface activation treatment station, the blended polymer of 80% by weight of nylon-MXD6 and 20% by weight of nylon 6 is extruded from the supply die 22a onto the inside back surface of the surface-activated paper substrate while being melted. To form a quality-retaining intermediate layer on the back side of the paper substrate. The blend polymer used shows two peaks by differential scanning calorimetry. To obtain a two-phase immiscible blend, that is, a blend exhibiting two melting points or melt intervals in the DSC measurement, the polymer must have a low melt temperature, relatively short blending time, and low shear when kneading. Should be blended in use. In practice, the various polymer granules are dry blended and then melt mixed in an extruder while feeding the polymer to an extrusion die. Two-phase blends provide better oxygen barrier properties than single-phase type blends.

The film immediately after being extruded can be easily joined by sufficiently passing it through a nip roll. Subsequently, the surface of the laminated quality-retaining intermediate layer was treated with 0.1.
Average density of 91, peak melting point at 160 ° C. by differential scanning calorimetry, melt flow index of 12, 1.5
The sealing innermost layer is laminated with a layer thickness of 25 μm of polypropylene having the characteristic parameter of swelling ratio of 25 μm. The swelling ratio measured here is the ratio of the diameter of the extrudate exiting from the die to the diameter of the die using an MFR measuring device which is a JIS thermoplastic flow test method.

From the laminated packaging material, a blank plate for a paper packaging container subjected to a crease line processing is punched, and then the edges of the blank plates are overlapped and welded to produce a sleeve. Next, the sleeve is mounted on a liquid food filling machine, and the bottom portion is folded along a predetermined ruled line and heat-sealed by hot air treatment to form a bottom portion, and then the contents are filled from the opening at the top portion. Thereafter, the top portion is folded along a predetermined ruled line and heat-sealed by hot air treatment to produce a gable-top type packaged product. The resulting packaging container is evaluated for “oxygen gas permeability”, “swelling”, “fragrance retention”, and “temperature dependency of the seal”. When green tea, orange gas, and milk are filled, the "oxygen gas permeability" is measured when the relative humidity is changed stepwise. The "bulging" test is one that is filled with orange juice
Using 0 1-liter gable-top paper containers, 10
The swelling of the container after 4 weeks of chilled storage at 4 ° C. is measured. When filling with green tea and orange gas, the relative humidity is changed stepwise and stored for 3 weeks and 2 months.
"Perfume retention" is measured. Change the temperature of the filling contents,
The effect of the seal on the seal ambient temperature is observed, and the “temperature dependency of the seal” is evaluated.

<Comparative Example 1> In Example 1, a low-density polyethylene (density = 0.923, MFI = 4, peak at 113 ° C. by differential scanning calorimetry) was used in place of polypropylene as the innermost layer of the sealing property. A packaging material and a paper packaging container are prepared in the same manner as in Example 1, except that the melting point is 1.8 (a swelling ratio of 1.8). Further, the obtained paper packaging container and packaging filling are evaluated in the same manner as in the examples.

The examples and comparative examples are evaluated for the above-mentioned "oxygen gas permeability", "temperature dependence of seal", "fragrance retention" and "bulging". As a result, it is understood that the example is superior to the comparative example. In conclusion, nylon-
It can be seen from the comparison with the comparative example that the mixture of MXD6 / PA6 has better oxygen barrier properties than amorphous PA. Also, a blend of nylon clay hybrid of PA6 and nylon-MXD6 is made of nylon PA.
It has better oxygen barrier properties than the 6-MXD6-blend, but can be seen by comparison. The comparative example shows that a good gas barrier value is obtained with a laminate of 100% nylon-MXD6 gas barrier layer, but such a laminate is not practically usable because the gas barrier layer is cracked and peeled And indicates that oxygen is allowed to permeate the packaging made therefrom.

In the example, when the filling liquid food was green tea, it was stored at 4 to 5 ° C. and 90% RH.
No increase in the oxygen concentration in the internal solution after weeks and two months is observed. In addition, there is no generation of foreign substances such as molds, and no reduction in taste, flavor and aroma, and other abnormalities are observed. Similarly,
When the liquid food is orange juice, the result of the similar evaluation is good. There is no generation of foreign substances such as molds, and no decrease in flavor and aroma and other abnormalities are observed. Further, in the embodiment, while a strong sealing strength is obtained,
Even for high-temperature filled liquid foods (green tea) of ~ 80 ° C, 3 ° C ~
Even in the case of low-temperature filling (milk) at 6 ° C., good sealing is obtained in a wide temperature range without being affected by the temperature of the filling content.

[0079]

According to the present invention demonstrated in the above embodiment, the following effects can be obtained. Perfumery properties that can be laminated by practically extrusion coating the basic multiple layers onto the paper core layer, thus effectively (efficiently) producing (converting) the packaging laminate material And a packaging laminate material having excellent gas barrier properties. In addition, it is possible to seal well in a wide range of sealing temperature from high temperature to low temperature, and therefore, it is easy to fill and pack in a paper packaging container, and it is possible to heat seal quickly,
In addition, a good sealing can be obtained without being affected by the temperature of the filling content, and a paper packaging laminate material having quality retention properties is provided.

Furthermore, extrusion coating (lamination) is possible, high cost performance is excellent, the mechanical strength of the container is excellent, the paper core layer can be thinned, the environmental load can be reduced, and heat sealing can be performed in a wide temperature environment. Provide a possible laminated packaging material.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a laminated packaging material according to the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the laminated packaging material according to the present invention.

FIG. 3 is a cross-sectional view showing still another embodiment of the laminated packaging material according to the present invention.

FIG. 4 is a schematic view schematically showing a method for producing the laminated packaging material shown in FIG. 1.

FIG. 5 is a schematic view schematically showing a method for producing the laminated packaging material shown in FIG. 2;

FIG. 6 is a schematic diagram schematically showing a method of manufacturing the laminated packaging material shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Laminated packaging material 11 Core layer 12 Quality holding | maintenance intermediate layer 13 Sealing innermost layer 15 Adhesive layer 20 Surface activation station 22a, b Supply die 23a, b Supply block

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuya Ono 6-12 Kioicho, Chiyoda-ku, Tokyo F-term in TETRAPACK Co., Ltd. 3E086 AD02 BA04 BA14 BA15 BA24 BB01 BB05 BB51 CA01 CA11 CA12 CA13 CA23 DA02 4F100 AA03B AK01B AK06 AK07C AK07E AK46B AK48B AK48D AL05B AL05D BA03 BA05 BA07 BA10A BA10C BA10E CA23B CB00 DE02B DG10A EH232 EJ12A EJ12B EJ55A EJ55B GB15 GB23 JA04C JA04E13J03E

Claims (10)

[Claims] 1. A paper core layer (11), a quality-retaining intermediate layer (12) laminated inside the core layer, and
A food packaging laminate material (10) comprising a heat-sealable innermost layer (13), wherein the quality-retaining intermediate layer comprises a polymer component A60 of a condensation polymer (nylon-MXD6) of meta-xylene diamine and adipic acid. Extrusion of ９５95% with 5-40% of polymer component B of nylon-6 (PA-6), nylon-66 (PA-66) or a blend of nylon-6 and nylon-66 (PA-6 / 66) An innermost layer comprising polypropylene having a narrow molecular weight distribution and having an average density of 0.88 to 0.92;
A food package having a peak melting point of 50C to 180C, a melt flow index of 10 to 40, a swelling ratio (SR) of 1.4 to 1.6, and a characteristic parameter of a layer thickness of 5 to 50 m. For laminated materials. 2. The packaging laminate according to claim 1, wherein the blend polymer comprises 60-95% by weight of nylon-MXD6 and 40-5% by weight of nylon-6. 3. A plurality of layers made of substantially the same material as the quality maintaining intermediate layer and the innermost layer, between the quality maintaining intermediate layer and the innermost layer laminated inside the paper core layer, or The packaging laminate according to claim 1, which is alternately laminated indirectly via an adhesive layer. 4. The polymer component B comprises PA-6, PA-66.
Or a molecular composite comprising a polyamide of PA-6 / 66 and finely divided layered silicates uniformly dispersed in the polyamide, according to claim 1. 5. A paper core layer (11), a quality-retaining intermediate layer (12) laminated inside the core layer, and
A method for producing a food packaging laminate material (10) comprising a heat sealable innermost layer (13), comprising 50 to 95% of a polymer component A of a condensation polymer (nylon-MXD6) of metaxylenediamine and adipic acid. ,
Nylon-6 (PA-6), Nylon-66 (PA-6)
6) Or a blend polymer of nylon-6 and nylon-66 (PA-6 / 66) with a polymer component B of 5 to 50% is directly extrusion coated on the core layer to form the quality-retaining interlayer. Laminate and co-extrude the following heat-sealable polymer simultaneously with the extrusion of the blended polymer, or extrude and coat the following heat-sealable polymer following extrusion of the blended polymer to form a heat-sealable innermost layer (13)
A method for producing a laminated material for food packaging characterized by laminating: at least polypropylene having a narrow molecular weight distribution, an average density of 0.88 to 0.92, and 150 ° C.
Peak melting point of ~ 180 ° C, melt flow index of 10-40, swelling ratio (SR) of 1.4-1.6
And heat-sealable polymers having characteristic parameters of layer thickness of 5 to 50 μm. 6. The laminated material for food packaging comprises a core layer of paper or paperboard, a condensation polymer of metaxylenediamine and adipic acid (nylon-MXD6) and nylon-6.
6. A quality maintaining intermediate layer of a blended polymer comprising (PA-6), said quality maintaining intermediate layer being applied to one side of the core layer together with the heat sealable innermost layer by coextrusion coating. The method for producing a laminated material for food packaging according to the above. 7. The quality-retaining interlayer is extrusion-coated directly onto the paper or paperboard core layer (11) by co-extrusion with a heat-sealable polymer without any intermediate lamination or adhesive layer. A method for producing a laminated material for food packaging according to claim 5. 8. The production of a laminated material for food packaging according to claim 5, wherein the co-extrusion of the heat-sealable innermost layer (13) and the quality-retaining intermediate layer is co-extruded together with an adhesive polymer between the layers. Law. 9. The production of a laminated material for food packaging according to claim 5, wherein the surface of the core layer (11) is pretreated and activated by corona or flame treatment before extrusion coating of the quality-retaining intermediate layer. Law. 10. The production of a laminated material for food packaging according to claim 5, wherein the contact surface of the extruded film is pretreated and activated by corona or flame treatment before extrusion coating of the quality-retaining intermediate layer. Law.