JP5810641B2 - Packaging material and paper container comprising the same - Google Patents

Description

  The present invention relates to a packaging material having a non-adsorptive sealant layer and a paper substrate layer in which the amount of organic compounds contained in contents such as pharmaceuticals, cosmetics and foods is reduced, and a paper container comprising the same. More specifically, since the adsorption amount of the organic compound in the contents is reduced, the packaging material having a sealant layer excellent in maintaining the quality of the contents and excellent in heat sealability, and paper comprising the same A container, in particular a liquid paper container.

In general, a paper container is made of a packaging material having a paper base layer and a sealant layer. As these sealant layers, a thermoplastic resin is used, and in particular, a high-pressure low-density polyethylene resin (LDPE, density 0.910 to 0.925 g / cm ³ ) and the like are excellent in terms of laminate processability and heat sealability. It is used.

  Although LDPE can achieve high adhesion strength by heat sealing, it is known that it can easily adsorb organic compound components. Therefore, the paper container having the sealant layer made of LDPE as the innermost layer, that is, the layer in contact with the contents, easily adsorbs the organic compound component contained in the contents and easily changes or deteriorates the contents.

On the other hand, in some cases, a medium density polyethylene resin (MDPE, density 0.926 to 0.940 g / cm ³ ) is used as the sealant layer. However, MDPE has a drawback that a stable sealing temperature range cannot be obtained because the heat sealing temperature during box making (molding of paper containers) must be set higher than LDPE in order to obtain sufficient adhesion strength. . Further, when heat-sealing at such a high temperature, MDPE is oxidized and an oxidized odor is generated. Therefore, in a paper container having a sealant layer made of MDPE as the innermost layer, the oxidized odor of the resin is easily transferred to the contents. Has drawbacks.

  In some cases, a polyester resin is used as the sealant layer (Patent Document 1). However, since the polyester-based resin has poor heat-sealability and is likely to cause a sealing failure at the time of box making, a paper container having a sealant layer made of such a resin has drawbacks such as leakage of contents.

JP-A-5-162737

  The present invention solves the above-mentioned problems and makes it difficult to adsorb organic compound components, that is, a packaging material having a sealant layer excellent in non-adsorbability and excellent in heat sealability, and a paper container comprising the same In particular, an object is to provide a liquid paper container.

As a result of various studies, the present inventor is a packaging material having at least a paper base layer, an adhesive layer for dry lamination, and a sealant layer laminated adjacently on the adhesive layer for dry lamination, The sealant layer includes a reinforcing layer adjacent to the dry laminate adhesive layer, a linear low density polyethylene resin (LLDPE, density 0.900 to 0.940 g / cm ³ ) layer, and a cyclic polyolefin resin layer. A packaging material, and a paper container made of the same, in particular a liquid paper container, achieve the above-mentioned object, and the reinforcing layer is a layer made of polyethylene resin (PE). I found.

The present invention is characterized by the following points.
1. A packaging material used for a liquid paper container, comprising at least a paper base layer, a dry laminate adhesive layer, and a sealant layer laminated adjacently on the dry laminate adhesive layer, wherein the sealant layer comprises: , A layer provided with a reinforcing layer adjacent to the adhesive layer for dry lamination, a linear low density polyethylene resin layer, and a cyclic polyolefin-based resin layer in this order, and the reinforcing layer is a layer made of a polyethylene resin. The packaging material as described above.
2. 2. The packaging material according to 1 above, wherein the sealant layer is a three-layer sealant film layer in which a reinforcing layer, a linear low-density polyethylene resin layer, and a cyclic polyolefin resin layer are provided in this order. .
3. The sealant layer is a four-layer sealant film in which a reinforcing layer, a first linear low-density polyethylene resin layer, a cyclic polyolefin-based resin layer, and a second linear low-density polyethylene resin layer are provided in this order. 2. The packaging material according to 1 above, which is a layer.
4). The sealant layer includes a reinforcing layer, a first linear low density polyethylene resin layer, a cyclic polyolefin resin layer, a second linear low density polyethylene resin layer, and a linear low density polyethylene resin containing an inorganic filler. 2. The packaging material according to 1 above, wherein the packaging material is a layer of a five-layer sealant film in which the layers are provided in this order.
5. 5. The packaging material according to any one of 1 to 4 above, wherein a barrier layer is provided between the paper base material layer and the dry laminate adhesive layer.
6). The barrier layer is made of an aluminum foil, an aluminum vapor deposition film, a silicon oxide vapor deposition film, an alumina vapor deposition film, an ethylene-vinyl alcohol copolymer film, a polyamide resin film, a polyvinylidene chloride resin film, and a polyacrylonitrile resin film. 6. The packaging material according to 5 above, which is a layer composed of at least one selected from the above.
7). 7. A liquid paper container formed by boxing the packaging material according to any one of 1 to 6 so that a sealant layer is an innermost layer.

  The packaging material of the present invention has a sealant film having a reinforcing layer made of PE, an LLDPE layer, and a cyclic polyolefin resin layer adjacent to each other.

  In general, it is known that a cyclic polyolefin-based resin has a high intermolecular force during melt film formation and causes aggregation between polymers. As a result, it is difficult to obtain a uniform film surface by agglomerating the resin throughout the film to form a knob-like gel mass. This tendency becomes more prominent during film formation by the inflation method, and the cyclic polyolefin resin film obtained by the method generates innumerable gel lumps on the entire surface.

  However, according to the present invention, by forming the cyclic polyolefin resin layer adjacent to the LLDPE layer and forming the film together, uneven aggregation of the molecules of the cyclic polyolefin resin is suppressed. Therefore, the sealant film of the packaging material of the present invention is easy to form, and can form a beautiful film that is homogeneous and has good transparency. In addition, the generation of gel lumps can be suppressed during high-speed film formation by the inflation method.

  In such a packaging material of the present invention, the cyclic polyolefin resin layer has a dense surface structure with a close intermolecular distance based on the high intermolecular force of the cyclic polyolefin resin, and the LLDPE layer has The film exhibits high interlayer adhesion with the cyclic polyolefin resin layer, and imparts good film forming stability to the cyclic polyolefin resin layer. The packaging material of the present invention having such a structure hardly adsorbs the components in the contents, that is, has excellent non-adsorption properties.

  In addition, the sealant layer that forms the packaging material of the present invention exhibits good heat-sealability, can be heat-sealed in a wide range of sealing temperatures, and exhibits sufficient sealing strength during box making even when heat-sealing at low temperatures. To do. Therefore, processing is easy and there is little generation | occurrence | production of resin oxidation odor etc.

Furthermore, the packaging material of the present invention is obtained by dry laminating a sealant film via a paper base material layer or a barrier layer or the like and an adhesive for dry laminating, thereby obtaining good content resistance. Further, this tendency becomes more prominent by bonding so that the surface of the sealant film on the reinforcing layer side is adjacent to the adhesive layer for dry laminating, and the packaging material of the present invention can be stored even if various contents are stored. High laminate strength is maintained and delamination does not occur.
Further, the reinforcing layer is melted by heat sealing at the time of box making, fills the gap generated in the stepped portion of the paper container, contributes to stable sealing, and allows the liquid filling into the paper container.

  Therefore, the packaging material of the present invention is suitable for forming a paper container, particularly a liquid paper container that is required to maintain the quality of contents.

It is a schematic sectional drawing which shows the example about the layer structure of the packaging material of this invention. It is a schematic sectional drawing which shows the example about the layer structure of the packaging material of this invention. It is a schematic sectional drawing which shows the example about the layer structure of the packaging material of this invention.

The above-described present invention will be described in more detail below.
<I> Layer Configuration of Laminate Forming Packaging Material of the Present Invention FIGS. 1 to 3 are schematic sectional views showing an example of the layer configuration of the packaging material of the present invention.

As shown in FIGS. 1 to 3, the packaging material of the present invention basically has a configuration in which a paper base layer 1 and a sealant layer 3 are dry-laminated via an adhesive layer 2 for dry lamination. Here, the sealant layer 3 includes a reinforcing layer (a) adjacent to the adhesive layer for dry lamination, an LLDPE layer (b, b ₁ , b ₂ ), a cyclic polyolefin resin layer (c), and, optionally, an inorganic filler. It has a containing LLDPE layer (d).

  As an embodiment of the packaging material of the present invention, as shown in FIG. 1, the sealant layer 3 includes a sealant film comprising a reinforcing layer (a), an LLDPE layer (b), and a cyclic polyolefin-based resin layer (c). Layer.

As another embodiment of the packaging material of the present invention, as shown in FIG. 2, the sealant layer 3 includes a reinforcing layer (a), a first LLDPE layer (b ₁ ), a cyclic polyolefin-based resin layer (c), and a second layer. This is a four-layer sealant film layer in which two LLDPE layers (b ₂ ) are provided in this order.

As still another embodiment of the packaging material of the present invention, as shown in FIG. 3, the sealant layer 3 includes a reinforcing layer (a), a first LLDPE layer (b ₁ ), a cyclic polyolefin-based resin layer (c), This is a five-layer sealant film layer in which the second LLDPE layer (b ₂ ) and the inorganic filler-containing LLDPE layer (d) are provided in this order.

  The packaging material of the present invention may have a barrier layer made of an arbitrary gas barrier film between the paper base layer 1 and the dry laminate adhesive layer 2 as necessary. In this case, the barrier layer and the sealant layer 3 are dry-laminated via the dry-laminate adhesive layer 2. The barrier layer and the paper substrate layer 1 can be laminated by any method such as sandwich lamination or dry lamination.

  The packaging material of the present invention may also have a layer made of any polyethylene resin (PE) on the surface opposite to the sealant layer as a surface protective layer that becomes the outermost layer of the paper container. The surface protective layer can be laminated on the surface of the packaging material by extrusion coating a molten PE resin or by laminating a PE film by any method.

  Hereinafter, the resin names used in the present invention are those commonly used in the industry. In the present invention, the density was measured according to JIS K7112.

<II> Paper base material layer As the paper base material constituting the paper base material layer of the present invention, various formability, flex resistance, rigidity, waist, strength, etc. are selected according to the application of the paper container to be applied. Arbitrary paper can be used, for example, the main strength material, strong size bleached or unbleached paper, or pure white roll paper, kraft paper, paperboard, processed paper, milk base paper, etc. Paper can be used.

The paper base material layer may be obtained by laminating a plurality of layers of these papers. The paper base material layer has a basis weight of 80 to 600 g / m ² , preferably a basis weight of 100 to 450 g / m ² , and a thickness of 110 to 860 μm, preferably 140 to 640 μm. If it is thinner than this, the strength as a container is insufficient, and if it is thicker than this, the rigidity becomes too high, and the processing may be difficult. Note that, for example, letters, figures, symbols, and other desired patterns can be arbitrarily formed on the paper base by a normal printing method.

<III> Adhesive Layer for Dry Laminate As an adhesive constituting the adhesive layer for dry laminate of the present invention, for example, one-pack or two-pack curable or non-cured vinyl type, (meth) acrylic type Solvent type such as polyamide, polyester, polyether, polyurethane, epoxy, rubber, etc., aqueous type or emulsion type can be used.

  Examples of the coating method for the dry laminating adhesive include a direct gravure roll coating method, a gravure roll coating method, a kiss coating method, a reverse roll coating method, a fountain method, and a transfer roll coating method. It can apply | coat to bonding surfaces, such as an adhesive film and a sealant film.

The coating amount is preferably 0.1 to 10 g / m ² (dry state), more preferably 1 to 5 g / m ² (dry state). If it is thinner than this, sufficient adhesive strength cannot be obtained, and if it is too thick, there is a concern of residual solvent.
Note that, for example, an adhesion promoter such as a silane coupling agent can be arbitrarily added to the dry laminate adhesive.

<IV> Sealant Layer The sealant layer of the present invention has a reinforcing layer, an LLDPE layer, and a cyclic polyolefin resin layer adjacent to each other in this order. In the packaging material of the present invention, the reinforcing layer is located on the surface (bonding surface) of the sealant layer and is adjacent to the adhesive layer for dry lamination.

i) Structure of sealant layer In one embodiment of the present invention, the sealant layer is a layer of a sealant film including only a reinforcing layer, an LLDPE layer, and a cyclic polyolefin-based resin layer. In the sealant layer having this configuration, the cyclic polyolefin-based resin layer becomes the outermost layer of the packaging material of the present invention, that is, the innermost layer of the paper container, and therefore can exhibit excellent non-adsorbability.

  In this configuration, the thickness of each layer in the sealant film can be appropriately set according to the application of the paper container to be applied, but in order to obtain the sealing strength necessary for box making, and stable film formation From the viewpoint of non-adsorbability and product cost, for example, the thickness of the reinforcing layer is 10 to 40 μm, more preferably 15 to 25 μm. If it is too thick, the low-temperature sealability is inferior, and if it is too thin, the step of the paper container The sealability of the gap generated in the part is deteriorated. The thickness of the LLDPE layer is 10 to 50 μm, more preferably 20 to 40 μm. If it is too thick, the punching suitability is inferior, and if it is too thin, the adhesion to the cyclic polyolefin resin layer is inferior. Furthermore, the thickness of the cyclic polyolefin-based resin layer is 5 to 20 μm, more preferably 5 to 10 μm. If it is too thick, the sealing property is inferior, and if it is too thin, the non-adsorbing property of the content is inferior.

  In another aspect of the present invention, the sealant layer is a four-layer sealant film in which a reinforcing layer, a first LLDPE layer, a cyclic polyolefin-based resin layer, and a second LLDPE layer are provided in this order. The sealant layer having this configuration has excellent laminate strength and content resistance, and can exhibit high seal strength while maintaining good non-adsorption properties.

  In this configuration, the thickness of each layer of the sealant film can be appropriately set according to the application of the paper container to be applied, but in order to obtain the sealing strength necessary for box making, stable film formation, From the standpoint of non-adsorbability and product cost, for example, the thickness of the reinforcing layer is 10 to 40 μm, more preferably 15 to 25 μm. If it is too thick, the low-temperature sealability is inferior, and if it is too thin, the step portion of the paper container The airtightness of the voids generated in the above is deteriorated. The thickness of the first LLDPE layer is 10 to 50 μm, more preferably 15 to 40 μm. If it is thicker than this, the punching suitability is inferior, and if it is too thin, the adhesiveness to the cyclic polyolefin resin layer is inferior. Moreover, the thickness of the cyclic polyolefin resin layer is 5 to 20 μm, more preferably 5 to 10 μm. If it is too thick, the sealing property is inferior, and if it is too thin, the non-adsorption property of the content is inferior. Furthermore, the thickness of the second LLDPE layer is 10 to 50 μm, more preferably 15 to 40 μm. If it is thicker than this, the punching suitability and non-adsorption property are inferior, and if it is too thin, the adhesion to the cyclic polyolefin resin layer is poor. Is inferior.

  In still another embodiment of the present invention, the sealant layer is composed of five layers in which a reinforcing layer, a first LLDPE layer, a cyclic polyolefin resin layer, a second LLDPE layer, and an inorganic filler-containing LLDPE layer are provided in this order. It is a layer of a sealant film. The sealant layer having this configuration has excellent laminate strength and content resistance, and can exhibit high seal strength while maintaining good non-adsorption properties. Furthermore, the film surface is slippery, and in the frame sealer in the paper container manufacturing process, the blank can be supplied smoothly and is easy to handle.

  In this configuration, the thickness of each layer of the sealant film can be appropriately set according to the application of the paper container to be applied, but in order to obtain the sealing strength necessary for box making, stable film formation, From the standpoint of non-adsorbability and product cost, for example, the thickness of the reinforcing layer is 10 to 40 μm, more preferably 15 to 25 μm. If it is too thick, the low-temperature sealability is inferior, and if it is too thin, the step portion of the paper container The airtightness of the voids generated in the above is deteriorated. The thickness of the first LLDPE layer is 10 to 50 μm, more preferably 15 to 40 μm. If it is thicker than this, the punching suitability is inferior, and if it is too thin, the adhesiveness to the cyclic polyolefin resin layer is inferior. Moreover, the thickness of the cyclic polyolefin resin layer is 5 to 20 μm, more preferably 5 to 10 μm. If it is too thick, the sealing property is inferior, and if it is too thin, the non-adsorption property of the content is inferior.

  Furthermore, the thickness of the second LLDPE layer is 10 to 50 μm, more preferably 15 to 40 μm. If it is thicker than this, the punching suitability and non-adsorption property are inferior, and if it is too thin, the adhesion to the cyclic polyolefin resin layer is poor. Is inferior.

  Moreover, the thickness of the inorganic filler-containing LLDPE layer is 5 to 20 μm, more preferably 5 to 10 μm. If it is too thick, the amount of the inorganic filler increases and the cost increases. Cannot be sufficiently obtained, and the slipperiness is poor.

ii) Reinforcing layer In the present invention, the reinforcing layer is a layer located on the surface of the sealant layer and adjacent to the adhesive layer for dry lamination. This reinforcing layer is made of polyethylene resin (PE) and melted by heat sealing during box making to increase the adhesive strength between the layers and further fill the gaps formed in the stepped portion of the paper container to improve the sealing performance of the container. .

As the PE for forming the reinforcing layer of the present invention, any polyethylene can be used, but it exhibits a melt viscosity (fluidity) suitable for filling the voids, and has film forming suitability and processability. A high-pressure low-density polyethylene resin (LDPE) having a density of 0.910 to 0.925 g / cm ³ and a melt flow rate (MFR) of 1 to 10 g / 10 min (190 ° C.) can be particularly preferably used.

iii) Linear Low Density Polyethylene Resin (LLDPE) Layer In the present invention, the LLDPE constituting the LLDPE layer in the sealant layer is a linear polyethylene having a density of 0.900 to 0.940 g / cm ³ and is a metallocene. It is a copolymer obtained by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms at low temperature and low pressure using a single site catalyst such as a catalyst or a multisite catalyst such as a Ziegler-Natta catalyst.

  Specific examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene and 1-decene. , 1-dodecene and the like.

  Examples of the copolymerization method include polymerization methods of ethylene and α-olefin, such as a low pressure method, a slurry method, a solution method, and a gas phase method.

  The LLDPE of the present invention has 3 to 25 short chain branches per 1000 carbon atoms as short chain branches, but is not distinguished from LDPE in that it does not have long chain branches exceeding about 20 carbon atoms. Usually, in LLDPE, the structural unit derived from ethylene is about 99.9 to 90 mol%, and the structural unit derived from α-olefin is about 0.1 to 10 mol%. In the present invention, LLDPE prepared with a metallocene catalyst can be suitably used because of excellent structural uniformity.

  Suitable LLDPE for use in the present invention includes “Sumikasen” manufactured by Sumitomo Chemical Co., Ltd.

  Further, the main component is LLDPE as described above, and if necessary, an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, an antiblocking agent, a flame retardant, a crosslinking agent, a colorant, etc. One or more of these additives may be added.

iv) Cyclic polyolefin resin layer In the present invention, the cyclic polyolefin resin constituting the cyclic polyolefin resin layer includes a ring-opening metathesis polymer (COP) obtained by polymerizing a cyclic olefin by a metathesis ring-opening polymerization reaction, Copolymers with α-olefins (chain olefins), that is, cyclic olefin copolymers (COC) are included.

  As the cyclic olefin, any cyclic hydrocarbon having an ethylenically unsaturated bond and a bicyclo ring can be used, particularly those having a bicyclo [2.2.1] hept-2-ene (norbornene) skeleton. preferable.

Specifically, bicyclo [2.2.1] hept-2-ene and derivatives thereof, tricyclo [4.3.0.1 ^2.5 ] -3-decene and derivatives thereof, tricyclo [4.4.0.1 ^2.5] -3-undecene and derivatives thereof, tetracyclo [4.4.0.1 ^2.5 .1 ^7.10] -3-dodecene and derivatives thereof, pentacyclo ^{[6.5.1.1 3.6 .0 2.7 .0 9.13]} - 4 pentadecene and its derivatives, pentacyclo ^{[7.4.0.1 2.5 .1 9.12 .0 8.13]} -3- pentadecene and its derivatives, pentacyclo ^{[6.5.1.1 3.6 .0 2.7 .0 9.13]} - 4,10 penta decadiene and its derivatives, pentacyclo ^{[8.4.0.1 2.5 .1 9.12 .0 8.13]} -3- hexadecene and it derivatives, and the like, without limitation. The cyclic olefin may have a polar group such as an ester group, a carboxyl group, and a carboxylic anhydride group as a substituent.

  As the α-olefin copolymerized with the cyclic olefin, ethylene, an α-olefin having 3 to 20 carbon atoms can be used, and specifically, ethylene, propylene, 1-butene, 1-pentene, 3-methyl. Examples include -1-butene, 1-hexene, 4-methyl-1-pentene, and preferably ethylene.

  In the present invention, the production of the ring-opening metathesis polymer is not particularly limited as long as it is a known ring-opening metathesis polymerization reaction, and can be produced by ring-opening polymerization of the above cyclic olefin using a polymerization catalyst. .

In the production of the cyclic olefin copolymer, 25 to 45 mol% of α-olefin and 55 to 75 mol% of cyclic olefin are randomly polymerized using a single site catalyst such as a metallocene catalyst or a multisite catalyst. Is made by
Ring-opening metathesis polymer and a cyclic olefin copolymer are preferably used in the present invention, some are commercially available, for example, Nippon Zeon Co., Ltd. of "ZEONOR ^(R)" and manufactured by Polyplastics Co., Ltd., "TOPAS ^{(R )} "And the like.

  In addition, in order to obtain the more uniform film | membrane surface in the said cyclic polyolefin resin in order to suppress the generation | occurrence | production of the gel lump by aggregation of cyclic polyolefin resin at the time of film forming, It can be added arbitrarily within a range not impairing the non-adsorption property. The olefin-based resin may be any polyethylene or polypropylene having a melt flow rate (MFR) at 190 ° C. of 5 to 40 g / 10 minutes, preferably 15 to 30 g / 10 minutes. it can. Moreover, as an addition amount, it is good to mix | blend an olefin resin with the ratio of 3-50 mass% of the whole, Preferably 5-10 mass%.

  If necessary, one or more additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, an antiblocking agent, a flame retardant, a crosslinking agent, and a colorant are added. May be.

v) Inorganic filler-containing LLDPE layer In the present invention, the inorganic filler-containing LLDPE layer is a layer made of a resin composition in which an inorganic filler is dispersed in LLDPE by a master batch type blending method.
In this resin composition, as the LLDPE that can be suitably used, the same resins as those described for the LLDPE layer can be used.

Further, suitable inorganic fillers which may be _{used, SiO 2, AL 2 O 3} , TiO 2, ZnO, Fe 2 O 3, SnO 2, CeO 2, NiO, PbO, S 2 Cl 2, ZnCl 2, FeCl 2 , CaCO ₃ , B ₂ O _{3, and the} like, and a filler having an average particle diameter of 2 to 15 μm can be used. Preferably, a silicon oxide SiO ₂ filler is used. When the average particle size of the inorganic filler is less than 2 μm, there is no effect in improving the slipperiness, and when the average particle size exceeds 15 μm, the container surface is rubbed by the inorganic filler protruding on the surface of the film forming film. And hurt. In addition, in this invention, an average particle diameter means the particle size of the particle which exists most by particle size distribution measurement. The particle size distribution can be measured by a Coulter counter method.

  In this resin composition, the inorganic filler is added in an amount of 2.0 to 5.0 wt% of the whole. When the content of the inorganic filler in the resin composition is less than 2.0 wt%, it is difficult for the filler to come out on the surface of the sealant layer, and the effect of improving slip failure is small. Moreover, since it will be in a saturated state in the sealant layer surface when it exceeds 5.0 wt%, even if it adds more fillers, the effect corresponding to this cost is not acquired. In addition, when the saturated state is reached, seal inhibition occurs, and conversely, the seal start temperature may be increased.

  If necessary, the resin composition may contain one or two additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, an antiblocking agent, a flame retardant, a crosslinking agent, and a colorant. More than seeds may be added.

  Further, in order to improve the film forming stability and the fluidity of the resin at the time of sealing the paper container, LDPE may be added to the resin composition in an amount of 0 to 20 wt%. However, it is not preferable to add LDPE in excess of 20 wt% because non-adsorption is impaired.

  By providing the inorganic filler-containing LLDPE layer in the outermost layer portion of the sealant layer, the slip characteristics can be improved without impairing the fluidity of the heat seal resin constituting the inside of the sealant layer. Therefore, the packaging material of this invention which has this inorganic type filler containing LLDPE layer maintains favorable heat-sealability, and shows the slip characteristic suitable for film forming and box making.

vi) Method for producing sealant film In the present invention, as a method for producing a sealant film having a three-layer structure, an inflation method or a cast method is used by using resins constituting the reinforcing layer, the LLDPE layer, and the cyclic polyolefin resin layer. Three layers are coextruded to form a film by coextrusion film formation.

  Alternatively, the LLDPE layer and the cyclic polyolefin resin layer may be laminated in this order on the PE film forming the reinforcing layer by the extrusion coating method, preferably by the coextrusion coating method. In order to increase the adhesive strength between the layers, an arbitrary surface treatment such as ozone treatment may be performed on the laminated surface of the PE film in advance.

  Similarly, a four-layer structure including the second LLDPE layer and a five-layer sealant film including the inorganic filler-containing LLDPE layer are produced by extrusion coating onto the PE film or by coextrusion film formation. be able to.

  High interlaminar adhesion and good film-forming stability are obtained, non-adsorbability and heat-sealability are further improved, and a beautiful film can be obtained. Therefore, LLDPE can be obtained by coextrusion, particularly by coextrusion film formation. It is preferable to form the layer and the cyclic polyolefin resin layer together. Furthermore, film formation by a coextrusion inflation method is particularly preferred because film formation at a low temperature is possible, there are few troubles of resin odor due to heating, and higher interlayer adhesion can be obtained.

<V> Barrier Layer In the packaging material of the present invention, a barrier layer having gas barrier properties can be provided between the paper base material layer 1 and the dry laminate adhesive layer 2 as necessary. Thereby, the smell leak of the content to the exterior and the penetration | invasion of oxygen and water vapor | steam gas from the outside can be suppressed, and the quality change of a content can be prevented.
As such a barrier layer, any gas barrier film can be used depending on the application of the paper container to be applied.

  For example, as the gas barrier film, a metal foil such as an aluminum foil, or a laminated film of a metal foil and a plastic film can be used. In this case, excellent gas barrier properties can be obtained and light shielding properties can be obtained. Become. The thickness of the metal foil used suitably or the laminated film of metal foil and a plastic film is about 6-30 micrometers.

  Moreover, you may use the vapor deposition film which has a vapor deposition layer of an inorganic oxide or a metal as a gas barrier film. Here, preferable examples of the inorganic oxide include aluminum oxide, silicon oxide, and magnesium oxide. Moreover, aluminum etc. are mentioned as a metal used suitably. Moreover, as a base film which carries a vapor deposition layer, the resin film which consists of polyester, polyamide, a polypropylene, etc. can be used. The thickness of the vapor deposition film used suitably is about 9-40 micrometers. In addition, when a barrier layer consists of a vapor deposition film, it is preferable to laminate | stack so that the vapor deposition film side may contact | connect a paper base material layer from viewpoints, such as handling at the time of a process.

Furthermore, as the gas barrier film, a gas barrier film made of at least one of ethylene-vinyl alcohol copolymer, polyamide resin, polyvinylidene chloride resin, and polyacrylonitrile resin can be used. The thickness of these gas barrier films that are preferably used is about 5 to 30 μm.
Moreover, you may select and use 2 or more types for a barrier layer from said various gas-barrier films.

  When the packaging material of the present invention has a barrier layer, the barrier layer and the sealant layer 3 are dry-laminated via the adhesive layer 2 for dry lamination. In addition, the barrier layer and the paper base material layer 1 can be manufactured by taking into account the manufacturing cost and required content resistance and the like, such as a sandwich laminating method using a thermoplastic resin or a dry laminating method using an adhesive for dry laminating. Lamination can be performed by any method. At this time, the surface of the paper substrate layer may be subjected to surface treatment such as corona treatment, flame treatment, anchor coating treatment, etc., and the surface of the barrier layer is subjected to in-line corona treatment, ozone treatment, etc. Also good. As the thermoplastic resin used for the sandwich laminate, a resin layer made of any thermoplastic resin that can be melted by heat and fused to each other can be used. For example, LDPE, MDPE, LLDPE, ionomer resin, ethylene -An acrylic acid copolymer etc. can be used.

<VI> Surface Protective Layer The packaging material of the present invention may have a layer made of any polyethylene resin (PE) on the surface opposite to the sealant layer as a surface protective layer that becomes the outermost layer during box making. .
The surface protective layer protects the outside of the paper base material layer and is bonded to the sealant layer by heating at the end portion of the packaging material. As the polyethylene, LDPE, LLDPE, MDPE, high density polyethylene (HDPE) and the like are used, and are not particularly limited. However, LDPE and LLDPE are preferable from the viewpoint of sealability and processability with the sealant layer of the packaging material of the present invention. Used.

  Although the formation method of a surface protective layer is not specifically limited, For example, it forms by carrying out extrusion coating of the molten polyethylene resin to one side of a paper base material layer. The surface protective layer is a layer that becomes the surface of the container, but a printing layer can be further provided on the surface, and in order to improve the adhesion of the printing ink used for the printing layer, the surface is a surface such as a corona treatment. Processing can also be performed. Although the thickness of a surface protective layer is not specifically limited, Usually, it is about 10-60 micrometers.

<VII> Use of packaging material The packaging material of the present invention can be suitably used to form a paper container, particularly a paper container that is required to maintain the quality of contents.
Production of a paper container from the packaging material of the present invention is usually performed as follows. That is, after printing as necessary on the surface of the packaging material of the present invention, it is punched out, and the end face is skived and hemmed so that the contents do not come into contact with the end face. Heat seal by heating, flame heating, etc. to make a paper container.

  The shape of the paper container may be determined as appropriate according to the use and purpose, and examples thereof include a gable top type, a brick type, a flat type, and a cylindrical paper such as a rectangular container or a round shape. A can etc. are mentioned. For example, a polyethylene cap, a pull tab-type opening mechanism, and the like may be appropriately provided at the spout of the paper container.

The content of the paper container is not particularly limited, either solid or gel-like, but liquids such as liquor, juices such as fruit drinks, various beverages such as mineral water, soy sauce, sauces, soups, etc. Liquid seasonings or various liquid foods and drinks such as curry, stew, and soup, edible oils, machine oils, chemicals such as adhesives and adhesives, cosmetics, miscellaneous goods such as pharmaceuticals, other shampoos, rinses and detergents It may be a chemical product or the like.
Next, the present invention will be specifically described with reference to examples.

[Example 1]
(1) LLDPE (manufactured by Ube Maruzen Polyethylene Co., Ltd., UM0540F) was used as a base resin, and silica (average particle size: 4.9 μm) was added thereto in an amount of 10 wt% of the whole to prepare a master batch. Blending 45 wt% of the master batch, 45 wt% of LLDPE (UM0540F manufactured by Ube Maruzen Polyethylene Co., Ltd.) and 10 wt% of LDPE (LC520 manufactured by Nippon Polyethylene Co., Ltd.) to prepare a resin composition for an LLDPE layer containing an inorganic filler did.

(2) LDPE (Nippon Polyethylene Co., Ltd. LC520), LLDPE (Ube Maruzen Polyethylene Co., Ltd., UM0540F), cyclic olefin copolymer (Polyplastics Co., Ltd. TOPAS ^(R) 8007F-500; Melt flow rate ( MFR) 1.9 g / 10 min (190 ° C.); density 1.02 g / cm ³ ), and the inorganic filler-containing LLDPE layer resin composition described in (1) above, by a coextrusion inflation method, A sealant film having a thickness of 60 μm was formed, comprising 5 layers of reinforcing layer 20 μm made of LDPE / first LLDPE layer 20 μm / cyclic olefin copolymer layer 5 μm / second LLDPE layer 10 μm / inorganic filler-containing LLDPE layer 5 μm. The obtained sealant film had a beautiful film surface without gel lump. In the description of the laminate in the present specification, “/” indicates that the left and right layers are laminated and integrated.

(3) A 12 μm thick polyethylene terephthalate (PET) film was laminated on a 6 μm thick aluminum foil by a dry lamination method using a two-component curable urethane-based adhesive to form a barrier film. The amount of adhesive applied at this time was such that the thickness of the adhesive was 3 g / m ² as a dry film.

(4) The surface on the reinforcing layer side of the sealant film formed in the above (2) and the surface on the PET film side of the barrier film formed in the above (3) are dry-laminated in the same manner as in the above (3). Barrier layer (aluminum foil / adhesive layer for dry laminate / PET film) / adhesive layer for dry laminate / sealant layer (reinforcing layer / first LLDPE layer / cyclic polyolefin-based resin layer / second LLDPE Layer / inorganic filler-containing LLDPE layer).

(5) On the other hand, LDPE (LC520 manufactured by Nippon Polyethylene Co., Ltd.) having a thickness of 20 μm as a surface protective layer is laminated on one surface of a paperboard having a basis weight of 340 g / m ² by the extrusion coating method. And an aluminum foil surface of the laminate film produced in (4) above, and an ethylene-methacrylic acid-methacrylic acid ester copolymer (N0908C, Mitsui DuPont Polychemical Co., Ltd.) having a thickness of 20 μm (adhesive resin) Layer) is extruded and sandwich laminated, surface protective layer / paper substrate layer / adhesive resin layer / barrier layer (aluminum foil / adhesive layer for dry laminate / PET film) / adhesive layer for dry laminate / sealant layer (reinforcement) Layer / first LLDPE layer / cyclic polyolefin resin layer / second LLDPE layer / inorganic filler-containing LLDP To obtain a packaging material of the present invention having a layer structure of the layer).

[Example 2]
As the sealant layer, a sealant film having a thickness of 60 μm composed of only three layers of LDPE reinforcing layer 20 μm / LLDPE layer 35 μm / cyclic olefin copolymer layer 5 μm is used, and the surface on the reinforcing layer side is in contact with the adhesive layer for dry lamination A packaging material of the present invention was produced in the same manner as in Example 1 except that lamination was performed. In addition, the resin similar to Example 1 was used for LDPE, LLDPE, and a cyclic olefin copolymer. The sealant film was formed by a coextrusion inflation method. The obtained sealant film had a beautiful film surface without gel lump.

[Comparative Example 1]
A packaging material was produced in the same manner as in Example 1 except that LLDPE (Ube Maruzen Polyethylene Co., Ltd., UM0540F) was used instead of the cyclic olefin copolymer.

[Comparative Example 2]
A packaging material was produced in the same manner as in Example 2 except that LLDPE (Ube Maruzen Polyethylene Co., Ltd., UM0540F) was used instead of the cyclic olefin copolymer.

[Adsorption test]
Using the packaging materials of Examples 1-2 and Comparative Examples 1-2, a menthol prepared by making a gable top type paper container with a side of 70 mm square and a capacity of 1 L, and having a menthol concentration of 5 μm / ml 1 l of ethanol solution was charged.
After storing for 2 weeks in an atmosphere at 50 ° C., the menthol content in the solution was measured by the GC / MS method. From the difference between the measured value and the menthol content before storage, the amount of menthol adsorbed per 1 cm ² of the inner wall of the paper container was determined. The results are shown in Table 1 below.

  In the paper container which consists of the packaging material of Examples 1-2, the adsorption amount of menthol was restrained to the low value. In contrast, the paper containers made of the packaging materials of Comparative Examples 1 and 2 adsorbed a large amount of menthol.

[Content resistance, laminate strength test]
Further, a test piece (15 mm width) was cut out from the paper container after being stored for 2 weeks, and the laminate state between the barrier layer and the sealant layer was examined. In any of the paper containers made of the packaging materials of Examples 1 and 2, no delamination was observed, and good laminate strength was maintained.

[Heat sealability test]
Using the packaging materials of Examples 1 and 2 and Comparative Examples 1 and 2 and printing the desired pattern and display on the surface of the surface protective layer by the offset printing method, then simultaneously punching into a predetermined shape is necessary A ruled line was provided at each location to obtain a blank sheet. Next, the barrel part was bonded together by a frame seal method to form a cylindrical sleeve, and this cylindrical sleeve was supplied to a filling machine (manufactured by DNK Co., Ltd., DR-10). The bottom part was heat-sealed with hot air from a filling machine, then the contents (mineral water) were filled, and finally the top part was heat-sealed to produce a gable-top type paper container (1.8 liter capacity). .

If the hot air temperature of the filling machine is too low, the adhesive strength becomes insufficient due to insufficient heating. On the other hand, if the temperature is too high, bubbling occurs in the seal portion due to overheating, and in either case, the contents leak or the container swells.
During the heat sealing of the bottom part and the top part of the packaging material of each Example and Comparative Example, the hot air temperature of the filling machine was changed every 10 ° C., and the hot air temperature range in which the contents were firmly adhered without leaking Was measured. The results are shown in Table 2 below.

  As in the comparative example, the packaging materials of Examples 1 and 2 can be heat-sealed in a wide temperature range, exhibit sufficient sealing strength even at a low temperature of 320 to 340 ° C., and have good heat-sealability. Indicated.

1: Paper base layer 2: Adhesive layer for dry lamination 3: Sealant layer a: Reinforcing layer b: Linear low density polyethylene resin layer b ₁ : First linear low density polyethylene resin layer b ₂ : No. Second linear low density polyethylene resin layer c: Cyclic polyolefin resin layer d: Inorganic filler-containing linear low density polyethylene resin layer

Claims (7)

A packaging material used for a liquid paper container, comprising at least a paper base layer, an adhesive layer for dry lamination, and a sealant layer laminated adjacently on the adhesive layer for dry lamination,
The sealant layer, the reinforcing layer adjacent to the dry laminate adhesive layer, linear low density polyethylene resin layer, and a set digit layer adjacent the cyclic polyolefin resin layer in this order,
The packaging material as described above, wherein the reinforcing layer is a layer made of polyethylene resin. The sealant layer is characterized in that the reinforcing layer is a layer of sealant film consisting of three layers digits set adjacent the linear low-density polyethylene resin layer and a cyclic polyolefin resin layer in this order, according to claim 1 Packaging material as described in. The sealant layer is a reinforcing layer, a first linear low density polyethylene resin layer, a cyclic polyolefin resin layer, and a second linear low density polyethylene resin layer 4 layers digits set adjacent in this order The packaging material according to claim 1, wherein the packaging material is a layer of a sealant film. The sealant layer includes a reinforcing layer, a first linear low density polyethylene resin layer, a cyclic polyolefin resin layer, a second linear low density polyethylene resin layer, and a linear low density polyethylene resin containing an inorganic filler. characterized in that a layer of the sealant film comprising five layers digits set adjacent layers in this order, the packaging material of claim 1.   The packaging material according to claim 1, further comprising a barrier layer between the paper base material layer and the dry laminate adhesive layer. The barrier layer is made of an aluminum foil, an aluminum vapor deposition film, a silicon oxide vapor deposition film, an alumina vapor deposition film, an ethylene-vinyl alcohol copolymer film, a polyamide resin film, a polyvinylidene chloride resin film, and a polyacrylonitrile resin film. The packaging material according to claim 5, wherein the packaging material comprises at least one selected from the above.   A liquid paper container formed by boxing the packaging material according to any one of claims 1 to 6 so that a sealant layer is an innermost layer.

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