JP3908522B2 - Packaging material with metal wind tone and barrier properties - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a packaging material having a metal wind tone and a barrier property, and more particularly to a packaging material having a metal wind tone and suitable for packaging an internal filling such as a liquid food having an improved barrier property. .
[0002]
[Prior art]
Conventionally, packaging materials based on paper, polyolefins containing inorganic fillers, polyolefin sheets and the like have been used as packaging materials for various objects. In order to protect the base material such as paper, polyolefin containing inorganic filler, polyolefin sheet, and internal filler, the base material such as paper, polyolefin containing inorganic filler, polyolefin sheet, and polyethylene, polypropylene, polyester, polychlorinated A laminate of materials such as plastic films such as vinyl is used.
[0003]
The package formed using the packaging material composed of this laminate is filled with an internal filler. To protect the filler, a barrier layer in which a metal foil is laminated on the substrate is used. It is performed by the extrusion lamination method or the dry lamination method of a barrier film. However, providing this barrier layer increases the cost because a large amount of material such as polymer is used.
[0004]
[Problems to be solved by the invention]
An object of this invention is to provide the packaging material which reduces the usage-amount of a raw material, and has a metal wind tone and barrier property.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to improve the above problems, the present inventors covered the surface of the base material layer with a black pigment-containing layer, and further provided a metal pigment-containing layer on the black pigment-containing layer. It has been found that the object of the present invention can be achieved, and the present invention has been reached.
[0006]
That is, the gist of the present invention is a packaging material in which a base material layer, a black pigment-containing layer, and a metal pigment-containing layer are joined in that order.
[0007]
The packaging material of the present invention is characterized in that the base material layer is made of paper, a filler-containing polymer layer or a polymer sheet.
The packaging material of the present invention is characterized in that the metal pigment has an aspect ratio of 100 or more.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The base material layer of the packaging material of the present invention comprises paper, a filler-containing polymer layer or a polymer sheet. As the paper for the base material layer, ordinary paper having a basis weight of 50 to 350 g / m ² can be used.
[0009]
As the filler-containing polymer layer of the base material layer, a polymer layer obtained by mixing a filler with a thermoplastic resin such as polyolefin, polyester, or polyvinyl chloride can be used, and a polyolefin layer containing an inorganic filler is particularly preferable. The polyolefin layer containing an inorganic filler is described in, for example, Japanese Patent No. 2848635. Examples of the polyolefin include polyethylene, polypropylene, polybutene-1 and the like as described in the above patent specification, and polypropylene is particularly preferable. Examples of polypropylene include a propylene homopolymer and a propylene-ethylene copolymer, particularly those having a melt flow rate (MFR) of 0.5 to 20 g / 10 min (ASTM D1238; 2.16 kg, 230 ° C.). Those are preferred. Examples of the inorganic filler include mica, talc and calcium salts such as calcium sulfate and calcium carbonate, and the content thereof is about 50 to 80% by mass.
[0010]
The thickness of the polyolefin layer containing an inorganic filler is 100 to 400 μm, preferably 250 to 350 μm. The polyolefin layer may be a laminate comprising two layers, each of which has a thickness of 50 to 200 μm, preferably 120 to 180 μm. The inorganic fillers in these two layers may be the same, but different ones are preferred. Moreover, in the case of a laminated body, what provided the foaming layer equivalent to those each layer in the middle or those thinner than them can be used among them. The laminate having the two-layer structure and the laminate having an intermediate layer are preferably produced by coextrusion molding.
[0011]
Examples of the polymer sheet for the base material layer include sheets made of thermoplastic resin such as polyolefin, polyester, polyvinyl chloride, polyamide, and polycarbonate. These thermoplastic resin sheets having a thickness of about 150 μm to 1 mm can be used. Examples of the polyolefin include polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, and the like. Examples of the polyester include polyethylene terephthalate and polybutylene terephthalate. Examples of the polyamide include polyamide 6, polyamide 6-6, polyamide-11, polyamide-12, polyamide MXD6, and the like.
[0012]
The black pigment in the black pigment-containing layer provided on the base material layer is typically carbon black, and iron black, titanium black, etc. can be used. The black pigment-containing layer may be one obtained by blending a black pigment into printing ink or thermoplastic resin in which a black pigment is dispersed. Examples of the thermoplastic resin include polyolefin, polyester, polyvinyl chloride, polyamide, and polycarbonate. As polyolefin, polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, etc., as polyester, polyethylene terephthalate, polybutylene terephthalate, etc., as polyamide, polyamide 6, polyamide 6-6, polyamide-11, Examples thereof include polyamide-12 and polyamide MXD6. In the case of printing ink, in addition to various resins, solvents, waxes, diluents, curing agents, etc., black pigments are contained in an amount of 5 to 20% by mass, preferably 10 to 15% by mass. The thickness of the printing ink is preferably in the range of 3 to 5 μm. In the case of using a thermoplastic resin blended with a black pigment, the content of the black pigment is not particularly specified, but is in the range of 0.5 to 15% by mass. The thickness of the black pigment-containing layer is preferably in the range of 1 to 15 μm.
[0013]
The black pigment-containing layer smoothes the surface of the substrate layer that is not smooth and absorbs visible light and ultraviolet rays that reach the substrate layer. Therefore, the black pigment-containing layer functions as a light barrier layer, and more clearly the appearance of the coating layer (metal pigment-containing layer) provided on the black pigment-containing layer without the reflected light from the surface of the base material layer. To do.
[0014]
The metal pigment of the metal pigment-containing layer further provided on the black pigment-containing layer is a pigment exhibiting metallic luster, and specific examples thereof include aluminum, silver, nickel, etc. 5 to 50 μm. The metal pigment preferably has a high aspect ratio of 100 or more, particularly 100 to 1,000. The metal pigment-containing layer is formed by blending the above metal pigment with a transparent matrix resin. Examples of the transparent matrix resin include polyethylene, polyethylene terephthalate, acrylic resin, polystyrene, transparent polyamide, polycarbonate, cycloolefin homopolymer, and cycloolefin copolymer. Content of the metal pigment in a metal pigment content layer is the range of 0.5-5 mass%. The thickness of the metal pigment-containing layer is preferably in the range of 1 to 15 μm.
[0015]
Since the metal pigment having a high aspect ratio as described above forms a lamella parallel to the surface of the metal pigment-containing layer, all the light is efficiently reflected in the same direction, which is good. Create a metallic style. Any visible light that penetrates the metal pigment-containing layer is absorbed by the black pigment-containing layer, so that the metal tone is not impaired at all. The transparent matrix resin of the metal pigment-containing layer exhibits good gloss and transparency, and brings about a metallic wind tone. Metal pigments with high aspect ratios make it more difficult for gases, moisture, scents, etc. to pass through the layer, resulting in improved barrier properties.
[0016]
These black pigment-containing layers are formed on the base material layer, and the metal pigment-containing layers are formed on the black pigment-containing layer, for example, (1) a method of gravure printing, offset printing or flexographic printing, (2) heating or ultraviolet light And / or a method of applying a gravure after curing by electron beam irradiation, (3) a method of extrusion coating with a matrix resin, or a method combining these methods.
[0017]
When packaging a packing material using the packaging material of the present invention consisting of a base material layer, a black pigment containing layer and a metal pigment containing layer, the base material layer side is in contact with the packing material or close to the contents, that is, It is used so that the base material layer is inside the packaging material. The packaging material of the present invention can be provided with one or more other member layers inside the base material layer.
[0018]
Examples of other member layers include a barrier layer, a thermoplastic resin layer, and an adhesive resin layer. The thickness of these barrier layers, thermoplastic resin layers, adhesive resin layers and the like is usually 5 to 25 μm. The barrier layer may be a barrier material alone or may have a multilayer structure including the barrier material. Examples of the barrier material include aluminum foil, silicon oxide-deposited polyethylene phthalate, ethylene-vinyl alcohol copolymer, and polyamide resin. The multilayer structure including a barrier material includes polyethylene film / aluminum foil, biaxially stretched film (/ adhesive) of adhesive polyethylene / silicon oxide-deposited polyethylene terephthalate, polyethylene film / adhesive / ethylene-vinyl alcohol copolymer film. / Adhesive, polyamide resin film / adhesive, and the like.
[0019]
The thermoplastic resin is selected from the above-mentioned thermoplastic resins, and is preferably a polyolefin, and particularly preferably polyethylene. Examples of the polyethylene include high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, and linear low density polyethylene (hereinafter referred to as mLLDPE) produced by using a metallocene catalyst. Particularly preferred are low density polyethylene and mLLDPE.
[0020]
mLLDPE has a molecular weight distribution The weight average molecular weight / number narrow 2-4 and an average molecular weight, but the density is preferably from 0.900~0.925g / cm ^3, density of 0.900~0.915g / cm ³ Are particularly preferred. A melt flow index (MFI: 190 ° C., load 2.16 kg) is preferably 10 to 20 g / 10 min.
[0021]
Such mLLDPE is an α-olefin having 4 to 8 carbon atoms of ethylene and comonomer in the presence of a metallocene catalyst, preferably 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, etc. Those produced by copolymerizing an α-olefin having a carbon number of 6 or more are desirable.
[0022]
The metallocene catalyst is a metallocene having a structure in which a transition metal such as titanium, zirconium, hafnium, etc. is sandwiched between unsaturated cyclic compounds containing a π-electron cyclopentadienyl group or a substituted cyclopentadienyl group, A combination with a promoter such as an aluminum compound such as alkylaluminoxane, alkylaluminum, aluminum halide, alkylaluminum halide, and the like.
[0023]
Examples of the resin of the adhesive resin layer include an acrylic resin type, a modified polyolefin type, an ethylene-vinyl acetate copolymer, a polyamide type, and an epoxy resin type. Examples of the acrylic resin include acrylic acid or methacrylic acid or a polymer or copolymer of an alkyl ester thereof. As modified polyolefins, organic peroxidation of unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, nadic acid, and nadic anhydride or their anhydrides to polyethylene, polypropylene, etc. Grafted in the presence of the product. In particular, a modified polyolefin system is preferred.
[0024]
Furthermore, the packaging material of this invention can provide a single or several other member layer in the outer side of a metal pigment content layer. Examples of other member layers include a print decoration layer, a colored layer, a seal layer, and the like. The print decoration layer is a layer in which characters, symbols, patterns, etc. are decorated with printing ink or the like, and the colored layer is a layer colored with a color pigment, and these may be usually used.
[0025]
As the sealing layer, a thermoplastic resin layer is preferable. The thermoplastic resin is selected from the thermoplastic resins described above, and polyethylene is particularly preferable. Examples of polyethylene include high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, and mLLDPE. Among these, low density polyethylene and linear low density polyethylene are particularly preferable. The thickness of the sealing layer is usually 5 to 200 μm.
[0026]
The following are mentioned as an example of the packaging material of this invention which provided the other member layer in the outer side of the metal pigment content layer.
Printing decoration layer / Metal pigment-containing layer / Black pigment-containing layer / Base material layer Printing decoration layer / Colored layer / Metal pigment-containing layer / Black pigment-containing layer / Base material layer sealing layer / Printing decoration layer / Metal pigment-containing layer / Black Pigment-containing layer / base material layer sealing layer / printing decoration layer / colored layer / metal pigment-containing layer / black pigment-containing layer / base material layer
In the case where a single or a plurality of other member layers are provided on the inner side of the base material layer or the outer side of the metal pigment-containing layer of the packaging material of the present invention, a method of joining the base material layer or the metal pigment-containing layer and those layers These layers can be joined by bonding each layer using an adhesive, heat-melting a layer that can be heat-melted and bonding it to a layer that is in contact with it, and layers that can be co-extruded simultaneously. Any of the methods conventionally used for producing a laminate, such as a method of extruding and laminating, a method of combining them, and the like can be employed.
[0028]
From the packaging material of the present invention, a rectangular parallelepiped such as a brick type, a rectangular parallelepiped with a roof represented by a 1 l milk container, a cube, a cylindrical shape, a parallel octagonal column, a central octagonal column and a top portion and a bottom portion A so-called prismatic type or pouch of a quadrangular shape can be formed in any conventionally known packaging container or the like.
[0029]
【Example】
Hereinafter, the present invention will be described in detail by way of examples. In addition,% in an example is the mass%.
[0030]
Example 1
^On the clay coated paper (base material layer) having a basis weight of 200 g / cm ² , printing was performed on the entire surface with a gravure printing ink containing 11% of a black pigment made of carbon black so as to have a thickness of 3 μm. A gravure printing ink containing 11% of a metal pigment made of fine aluminum flakes (aspect ratio 500) having a thickness of 300 angstroms (30 nm) and an average particle diameter of 15 μm is formed on the black pigment-containing layer to a thickness of 3 μm. The whole surface was printed so as to be. Next, the metal pigment-containing layer was printed and decorated with gravure printing ink containing three primary color pigments and a black pigment.
Further, by an extrusion coating method, an adhesive resin layer (polypropylene grafted with maleic anhydride), a barrier layer (ethylene-vinyl alcohol copolymer), and adhesiveness are formed on the opposite side of the base material layer provided with the above layers. A resin layer (polypropylene grafted with maleic anhydride graft) and mLLDPE layer (innermost layer) are formed in that order, and a low density polyethylene (LDPE) layer (outermost layer) is formed on the printed decorative layer. A packaging material was prepared.
About the obtained packaging material, the light transmittance was measured using a spectro UV meter (hereinafter the same), and as a result, the light transmittance was less than 10% in both the ultraviolet region and the visible light region. . The oxygen transmission rate was 2 cm ³ or less / m ² · 24 hours, and the water vapor transmission rate was 2 g or less / m ² · 24 hours. Furthermore, when the surface glossiness of 60 degrees (JIS Z8741) (hereinafter the same) was measured, it was 50% or more, and it was a metal-like glossiness.
[0031]
(Comparative Example 1)
The clay coated paper used in Example 1 was printed and decorated with gravure printing ink containing three primary color pigments and a black pigment. Next, an adhesive resin layer, a barrier layer, an adhesive resin layer, and an mLLDPE layer (innermost layer) are formed on the opposite side of the base material layer provided with the printed decorative layer by an extrusion coating method in the same manner as in Example 1. While providing, the LLDPE layer (outermost layer) was formed on the printing decoration layer, and the packaging material was produced.
[0032]
When the light transmittance of the obtained packaging material was measured, it was 20% or less in the ultraviolet region, but it was 60% or more in the visible light region, and sufficient light barrier properties were not obtained. Further, when the glossiness was measured, the gloss was less than 50%, and no metal-like gloss was obtained.
[0033]
(Example 2)
Example 1 except that instead of the clay-coated paper used in Example 1, a composite film having a basis weight of 150 g / m ² composed of polypropylene film / polypropylene film containing 60% by mass of polypropylene film / calcium carbonate was used. Similarly, the packaging material of the present invention was produced. About the obtained packaging material, when the light transmittance, oxygen transmission rate, water vapor transmission rate, and glossiness were measured in the same manner as in Example 1, the same good performance as in Example 1 was shown.
[0034]
(Comparative Example 2)
A packaging material was produced in the same manner as in Comparative Example 1 except that the composite film used in Example 2 was used instead of the clay-coated paper used in Example 1. About the obtained packaging material, when the light transmittance was measured like Example 1, the light transmittance of less than 10% was not obtained in the ultraviolet region and the visible light region. Further, when the glossiness was measured, the same result as in Comparative Example 1 was obtained.
[0035]
(Example 3)
LDPE containing 1% of black pigment was extrusion coated on paper (bleached paper) having a basis weight of 200 g / m ² to form a layer having a thickness of 10 μm. On this black pigment-containing layer, LDPE containing 1% of a metal pigment composed of fine aluminum flakes used in Example 1 was extrusion coated to form a layer having a thickness of 10 μm. Next, the metal pigment-containing layer was printed and decorated with gravure printing ink containing three primary color pigments, a black pigment, and a white pigment. Further, a packaging material of the present invention was produced in the same manner as in Example 1. When the light transmittance and glossiness of the obtained packaging material were measured in the same manner as in Example 1, the same good performance as in Example 1 was shown.
[0036]
(Comparative Example 3)
A packaging material was prepared in the same manner as in Comparative Example 1 except that the paper (bleached paper) used in Example 3 was used instead of the clay-coated paper used in Example 1. About the obtained packaging material, when the light transmittance was measured like Example 1, the light transmittance of less than 10% was not obtained in the ultraviolet region and the visible light region. Further, when the glossiness was measured, the same result as in Comparative Example 1 was obtained.
[0037]
(Comparative Example 4)
A packaging material was produced in the same manner as in Example 1 except that printing with gravure printing ink containing a metal pigment applied on the black pigment-containing layer was not performed. About the obtained packaging material, the light transmittance was measured in the same manner as in Example 1. The light transmittance was less than 10% in both the ultraviolet region and the visible light region in both the ultraviolet region and the visible light region. As a result, a metal-like luster of 50% or more was not obtained.
[0038]
(Comparative Example 5)
In Example 1, a packaging material was produced in the same manner as in Example 1 except that printing with a gravure printing ink containing a black pigment was not performed. When the light transmittance of the obtained packaging material was measured in the same manner as in Example 1, the light transmittance in both the ultraviolet region and the visible light region was not less than 10% in both the ultraviolet region and the visible light region. However, when the glossiness was measured, a metal-like gloss of 50% or more was obtained.
[0039]
(Comparative Example 6)
In Comparative Example 5, a packaging material was produced in the same manner as Comparative Example 5 except that gravure printing ink containing fine aluminum flakes (aspect ratio 10) having a thickness of 2 μm and an average particle diameter of 20 μm was used. About the obtained packaging material, when the light transmittance was measured like Example 1, light transmittance was not less than 10% in the ultraviolet region and visible light region. Further, when the glossiness was measured, a metal-like luster of 50% or more was not obtained, and the color became gray.
[0040]
【The invention's effect】
The packaging material of the present invention has excellent barrier properties such as light barrier properties, oxygen barrier properties, and water vapor barrier properties, and has a metallic-like gloss.

Claims (2)

A packaging material in which a base material layer, a black pigment-containing layer, and a metal pigment-containing layer are joined in this order , wherein the metal pigment has an aspect ratio of 500 to 1000 and an average particle size of 15 to 50 µm .   The packaging material according to claim 1, wherein the base material layer is made of paper, a filler-containing polymer layer or a polymer sheet.