JP7327604B2 - Packaging materials, packaging containers, lids and labels - Google Patents

Description

TECHNICAL FIELD The present invention relates to packaging materials, packaging containers, lids and labels.

In recent years, as a method for marking the date of manufacture, expiration date, manufacturer name, product name, serial number, etc. on the surface, it is a non-contact, high marking speed, and can be marked without being bound by the surface shape of a wide range of materials. Laser marking is popular.
Laser marking is recently attracting attention as a preferred marking method from the standpoint of hygiene and the environment because it does not require the use of ordinary ink containing a solvent because it marks directly on the material itself.

As described above, since laser marking is excellent in terms of hygiene, it is also used in packaging materials for foods, cosmetics, and the like.
However, resins such as plastic films have low sensitivity to the wavelength of general-purpose lasers, so when laser marking film packaging materials, a coloring layer containing metal oxides such as titanium oxide is formed on the plastic film. A means has been proposed (for example, Patent Document 1).

JP 2016-137719 A

Information such as characters marked by laser marking has a black color. For this reason, in film packaging materials, it is conceivable to increase the lightness (L ^* value) of the coloring layer in order to make it easier to distinguish marked characters and the like.
However, when the lightness (L ^* value) of the coloring layer is increased in the film packaging material as in Patent Document 1, bleeding of the laser-marked characters becomes conspicuous, which hinders management and inspection based on the marked characters. There was a problem that there were many cases that caused

The present invention has been made to solve the above technical problems, and a film packaging material that suppresses bleeding of marked characters and the like and has good contrast of characters, and An object of the present invention is to provide a packaging container, a lid and a label using the packaging material.

As a result of intensive research, the present inventors have found that the cause of bleeding is the weak interfacial adhesive strength of the ground color layer (color-developing layer) of the film packaging material, and have completed the present invention.
That is, the present invention provides the following [1] to [4].
[1] A packaging material having a configuration in which a plastic film, a background layer and a sealant layer are laminated in this order from the outer layer side, wherein the background layer contains titanium oxide and a binder resin, and the packaging material is The L ^* value in the CIE L ^* a ^* b ^* color system measured from the outer layer side is 91.8 or more, and the interlayer adhesive strength between the ground color layer and the layer in contact with the ground color layer is 0.5 N/15 mm. That's it, the packaging material.
[2] A packaging container at least partially comprising the packaging material described in [1] above.
[3] A lid, at least a part of which is made of the packaging material described in [1] above.
[4] A label at least partially formed of the packaging material described in [1] above.

According to the present invention, it is possible to provide a packaging material, a packaging container, a lid, and a label in which bleeding of marked characters and the like is suppressed and the contrast of the characters and the like is good in film packaging materials.

1 is a schematic cross-sectional view showing one aspect of a laminated structure of a packaging material of the present invention; FIG. FIG. 4 is a schematic cross-sectional view showing another aspect of the laminated structure of the packaging material of the present invention. It is a sectional view showing an example of a pouch for microwave ovens among packaging containers of the present invention. 1 is a top view showing an example of a lidded container among packaging containers of the present invention. FIG. FIG. 5 is a sectional view along IV-IV in FIG. 4; FIG. 4 is a schematic cross-sectional view showing another example of the laminated structure of the packaging material of the present invention; Fig. 2 is a schematic plan view showing another example of a pouch for microwave ovens in the packaging container of the present invention. FIG. 8 is a cross-sectional view taken along line XI-XI of FIG. 7; FIG. 4 shows the change in tensile stress with respect to the distance between a pair of grippers pulling on a plastic film and a sealant layer to measure interlayer adhesion.

Hereinafter, the packaging material of the present invention, and the packaging container and lid using the packaging material will be described in detail. Note that the notation of a numerical range of "AA to BB" in this specification means "from AA to BB".

[Packaging material]
The packaging material of the present invention is a packaging material having a configuration in which a plastic film, a background layer and a sealant layer are laminated in this order from the outer layer side, wherein the background layer contains titanium oxide and a binder resin, The L ^* value of the CIE L ^* a ^* b ^* color system measured from the outer layer side of the packaging material is 90 or more, and the interlayer adhesion between the ground color layer and the layer in contact with the ground color layer is 0.5 N. /15 mm or more.

<L ^* value and interlayer adhesion>
The packaging material of the present invention has an L ^* value of 90 or more in the CIE L ^* a ^* b ^* color system measured from the outer layer side of the packaging material, and the interlayer adhesion between the base color layer and the layer in contact with the base color layer. is required to be 0.5 N/15 mm or more.

The L ^* value in the CIE L ^* a ^* b ^* color system is preferably measured at an incident angle of 5°, as described in Examples below. In addition, when the packaging material as a whole has light transmittance, it is preferable to measure the L ^* value with white paper (white backing defined in ISO 13655) placed on the inner layer side of the packaging material.

The interlaminar adhesive strength between the ground color layer and the layer in contact with the ground color layer was measured by preparing a rectangular test piece in which the plastic film and the sealant layer were peeled off 15 mm in the long side direction, as described in Examples below. Then, grip the peeled part of the plastic film with one gripper of the measuring instrument, grip the peeled part of the sealant layer with the other gripper of the measuring instrument, and move the two grippers in opposite directions. It can be measured by pulling the
According to the measuring method, the weakest interlayer adhesion among the layers constituting the packaging material is measured. If the weakest interlayer adhesion is 0.5 N/15 mm or more, The interlaminar adhesive strength between the ground color layer and the layer in contact with the ground color layer can also be considered to be 0.5 N/15 mm or more.
Moreover, in the case of the above measuring method, any layer may undergo cohesive failure. However, for example, when the adhesive layer of the packaging material undergoes cohesive failure at a tensile stress of 0.5 N/15 mm, the interlayer adhesive strength between the ground color layer and the layer in contact with the ground color layer is 0.5 N/15 mm or more. can be regarded as Also, even if the ground color layer cohesively fails at a tensile stress of 0.5 N/15 mm, it can be considered that the interlaminar adhesive strength between the ground color layer and the layer in contact with the ground color layer is 0.5 N/15 mm or more.

If the L ^* value is less than 90, the contrast between laser-marked characters and the background will be insufficient. Further, when the interlayer adhesive strength between the ground color layer and the layer in contact with the ground color layer is less than 0.5 N/15 mm, suppression of bleeding of characters and the like is insufficient. In addition, when the interlayer adhesive strength between the ground color layer and the layer in contact with the ground color layer is weak, the cause of bleeding is that a gap is generated between the ground color layer and the layer in contact with the ground color layer during laser marking, This is presumably because a resin blackened by heat or a coloring agent self-coloring by heat enters into these gaps or gaps due to the formation of voids in the background layer.
On the other hand, the packaging material of the present invention has an L ^* value of 90 or more and an interlayer adhesive strength of 0.5 N/15 mm or more. , it is possible to suppress bleeding during laser marking.
In addition, the higher the L ^* value of the packaging material, the more conspicuous the bleeding of letters or the like during laser marking. That is, the packaging material of the present invention has an advantage (good contrast) by increasing the L ^* value, and furthermore, the adverse effect (conspicuous bleeding) by increasing the L ^* value is reduced by the occurrence of bleeding itself. can be reduced by suppressing

The L ^* value in the CIE L ^* a ^* b ^* color system, which is measured from the outer layer side of the packaging material, is preferably 92 or more. Although the upper limit of the L ^* value is not particularly limited, it is usually about 95.

The interlayer adhesive strength between the ground color layer and the layer in contact with the ground color layer is preferably 1.0 N/15 mm or more, more preferably 1.4 N/15 mm or more, and 2.0 N/15 mm or more. is more preferable, and 2.4 N/15 mm or more is even more preferable. The upper limit of the interlayer adhesive strength between the background layer and the layer in contact with the background layer is not particularly limited, but is about 4.0 N/15 mm. When the interlayer adhesive strength between the ground color layer and the layer in contact with the ground layer is set to be light, the upper limit of the interlayer adhesive strength may be set to about 2.2 N/15 mm.

<Lamination structure>
1 and 2 are schematic cross-sectional views showing an embodiment of the laminated structure of the packaging material 100 of the present invention.
The packaging material 1 in FIGS. 1 and 2 has an outer layer side (surface side) on the top and an inner layer side (back side) on the bottom, and the plastic film 2, the background layer 3 and the sealant layer 4 are outer layers in this order. Laminated from the side. In the packaging material 1 shown in FIG. 2, the background layer 3 has a two-layer structure of a first background layer 3a and a second background layer 3b. Moreover, the packaging material 1 of FIG. 2 has a gas barrier layer 5 between the background layer 3 and the sealant layer 4 .
In addition, the packaging material 1 of the present invention is not limited to the modes shown in FIGS. 1 and 2 .
The configuration of each layer will be described below.

Specifically, the packaging material of the present invention can be exemplified by the following laminated structure in order from the outer layer side. In addition, "/" means the boundary of each layer.
(1) Plastic film/underground layer/sealant layer (2) Plastic film/underground layer/gas barrier layer/sealant layer (3) Plastic film/underground layer/intermediate substrate layer/sealant layer (4) Plastic film/ Base color layer/Gas barrier layer/Intermediate substrate layer/Sealant layer

<Plastic film>
The plastic film 2 is positioned on the outer layer side of the background layer 3 .
Since the plastic film 2 is positioned on the outer layer side of the base color layer 3, components that develop colors in the base color layer 3 during laser marking (for example, resin that is blackened by heat, color former that self-colors by heat). can be suppressed from being released from the outer layer side of the ground color layer 3 to the outside, and the density of characters, images, etc. formed on the ground color layer 3 can be increased.

The plastic film 2 is made of a light-transmissive material so that the background layer 3 can be visually recognized from the outside.
Specifically, polyolefin resins such as polyethylene (PE) and polypropylene (PP), cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymer (AS) resins, acrylonitrile-butadiene-styrene copolymers (ABS) resin, poly (meth) acrylic resin, polycarbonate resin, polyvinyl alcohol resin, ethylene-vinyl alcohol copolymer (EVOH), ethylene-vinyl ester copolymer saponified product, polyethylene terephthalate (PET) and poly Polyester resins such as butylene terephthalate (PBT) and polyethylene naphthalate (PEN), polyamide resins such as various nylons (Ny), polyurethane resins, acetal resins, cellulose resins, polyvinylidene chloride resins (PVDC), etc. is mentioned.
The plastic film may be uniaxially or biaxially oriented. Also, a composite film in which two or more of the above resin films are laminated may be used. These plastic films may be formed by an inflation method or a melt extrusion coating method.
The plastic film is preferably subjected to corona discharge treatment, plasma treatment, or the like, in order to increase the adhesive strength with the background layer.

The melting point of the plastic film is preferably 150° C. or higher, more preferably 200° C. or higher, and even more preferably 250° C. or higher.
By setting the melting point of the plastic film to 150° C. or higher, deformation of the plastic film due to heat (for example, heat when drying the background layer forming ink in the process of manufacturing the packaging material) is suppressed, and the plastic film It is possible to easily increase the interlayer adhesion between the base layer and the base color layer.

From the viewpoint of heating in a microwave oven and retorting, the plastic film preferably has excellent heat resistance. Polyester-based resins, polyamide-based resins, and the like are examples of resins that constitute plastic films having excellent heat resistance.
Specific examples of plastic films having excellent heat resistance include a single polyester film, a single polyamide film such as nylon, and a composite film containing one or more of a polyester film and a polyamide film. Examples of the composite film include a coextruded stretched film composed of PET/Ny/PET and PET/Ny from the outer layer side. As the composite film, it is also preferable to combine one or more of polyester film and polyamide film with one or more of ethylene-vinyl alcohol copolymer film and polyvinylidene chloride film.

The thickness of the plastic film is not particularly limited, and can be appropriately set according to the use of the packaging material. is 10-25 μm.

The plastic film preferably has a total light transmittance of 85% or more, more preferably 90% or more, according to JIS K7361-1:1997. The plastic film preferably has a haze of JIS K7136:2000 of 1.0% or less, more preferably 0.5% or less, even more preferably 0.3% or less.
By setting the total light transmittance and the haze within the above ranges, the visibility of characters and the like formed on the background layer can be easily improved.

Both surfaces of the plastic film preferably have an arithmetic mean roughness Ra of 0.1 μm or less, more preferably 0.05 μm or less at a cutoff value of 0.8 mm measured according to JIS B0601:1994. .
By setting the Ra of both surfaces of the plastic film within the range described above, the visibility of characters and the like formed on the ground color layer can be easily improved.

<Ground layer>
A ground color layer 3 is located between the plastic film 1 and the sealant layer 4 .
Information such as characters is recorded on the background layer 3 by blackening the binder resin due to heat during laser marking. Further, when the background layer 3 contains a coloring agent, which will be described later, the coloring agent itself develops color, so that information such as characters can be recorded.

The background layer 3 contains titanium oxide and a binder resin.
Titanium oxide imparts laser marking aptitude to the base color layer 3, and increases the L ^* value of the background of the base color layer to enhance the contrast between the characters recorded by laser marking and the background. It has the role of making characters, etc., easier to see.
Titanium oxide is classified into an anatase type, a rutile type, and a brookite type according to its crystal structure, and any of these types can be used. and brookite type are preferred.

The content of titanium oxide is preferably 10 to 90% by mass, more preferably 50 to 90% by mass, and even more preferably 70 to 85% by mass of the total solid content of the background layer.
By setting the content of titanium oxide to 10% by mass or more, the color development property of the ground color layer is enhanced, the hiding property of the ground color layer is enhanced, and the L ^* value of the ground color layer is increased, resulting in laser marking. It is possible to increase the contrast between the rendered image and the background. In addition, by setting the content of titanium oxide to 90% by mass or less, it is possible to easily increase the interlayer adhesion between the ground color layer and the layer in contact with the ground color layer, and the coating film strength (cohesion) of the ground color layer. can suppress the decrease in
When the background layer is composed of two or more layers, the content of titanium oxide in each layer is preferably within the range described above.
The average particle size of titanium oxide is preferably 1 to 20 μm, more preferably 2 to 10 μm.

The binder resin of the background layer includes a cured product of a curable resin composition and a thermoplastic resin. A thermoplastic resin is preferable from the viewpoint of suppressing cracks during processing such as bending, and a cured product of a curable resin composition is preferable from the viewpoint of heat resistance during heating in a microwave oven or retorting.
When the ground color layer is formed of two or more layers, each color layer preferably contains the same kind of binder resin in order to improve the interlayer adhesion between the ground color layers.

Thermoplastic resins for the background layer include polyolefin resins such as polyethylene resins and chlorinated polypropylene resins, poly(meth)acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, and vinyl chloride-vinyl acetate resins. Copolymers, polystyrene resins, styrene-butadiene copolymers, vinylidene fluoride resins, polyvinyl alcohol resins, polyvinyl acetal resins, polyvinyl butyral resins, polybutadiene resins, polyester resins, polyamide resins, alkyd resins Resins, unsaturated polyester resins, polyurethane resins, xylene resins, maleic acid resins, cellulose resins such as nitrocellulose, ethyl cellulose, acetylbutyl cellulose, ethyloxyethyl cellulose, rubber resins such as chlorinated rubber and cyclized rubber , petroleum-based resins, and natural resins such as rosin and casein.

Examples of the cured product of the curable resin composition for the background layer include a cured product of a thermosetting resin composition and a cured product of an ionizing radiation-curable resin composition.
A thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition that is cured by heating. Thermosetting resins include acrylic resins, urethane resins, phenol resins, urea melamine resins, epoxy resins, unsaturated polyester resins, silicone resins, and the like. If necessary, a curing agent is added to these curable resins in the thermosetting resin composition. Here, it is preferable to select a curing agent that reacts with the components contained in the layer in contact with the ground color layer, in that the interlaminar adhesive strength between the ground color layer and the layer in contact with the ground color layer can be increased.
The ionizing radiation-curable resin composition is a composition containing a compound having an ionizing radiation-curable functional group (hereinafter also referred to as an "ionizing radiation-curable compound"). Examples of ionizing radiation-curable functional groups include ethylenically unsaturated bond groups such as (meth)acryloyl groups, vinyl groups, and allyl groups, epoxy groups, and oxetanyl groups. As the ionizing radiation-curable compound, a compound having an ethylenically unsaturated bond group is preferable, and a compound having two or more ethylenically unsaturated bond groups is more preferable. Polyfunctional (meth)acrylate compounds are more preferred. Both monomers and oligomers can be used as polyfunctional (meth)acrylate compounds.
Ionizing radiation means an electromagnetic wave or a charged particle beam that has an energy quantum capable of polymerizing or cross-linking molecules, and usually ultraviolet (UV) or electron beam (EB) is used. Electromagnetic waves such as X-rays and γ-rays, and charged particle beams such as α-rays and ion beams can also be used.

The binder resin of the ground color layer contains a urethane-based resin from the viewpoint of improving the adhesion between the ground color layer and the layer in contact with the ground color layer (e.g., plastic film, adhesive layer, sealant layer). is preferred.
For example, when the plastic film is made of polyester or polyamide, the interlayer adhesion between the plastic film and the background layer can be easily increased by including a urethane-based resin as the binder resin of the background layer.
Further, when having an adhesive layer in contact with the ground color layer, (i) the ground color layer contains a urethane resin as a binder resin, and the adhesive layer contains a polyester resin, (ii) the ground color layer (iii) the adhesive layer contains a curing agent, and the curing agent reacts with the components contained in the ground color layer, etc. Thus, the interlayer adhesive strength between the ground color layer and the adhesive layer can be easily increased. Examples of curing agents include isocyanate-based curing agents, and components that react with isocyanate-based curing agents include components having hydroxyl groups and isocyanate groups.

The content of the binder resin in the ground color layer is preferably 10 to 90% by mass, more preferably 10 to 50% by mass, more preferably 15 to 30% by mass, of the total solid content constituting the ground color layer. It is even more preferable to have
When the ground color layer is composed of two or more layers, the content of the binder resin in each layer is preferably within the range described above.

A coloring agent may be contained in the background layer in order to enhance color development by laser marking. The coloring agent generates heat when irradiated with a laser, and has the role of coloring itself or coloring the surrounding resin (carbonizing the resin to make it black).

As the coloring agent, one or more selected from the group consisting of metals such as bismuth, antimony, copper, molybdenum, iron, zinc, tin, gold, silver, cobalt and nickel, and compounds containing these metals. can be done. Among these, one or more selected from the group consisting of metals consisting of bismuth, antimony, copper and molybdenum, and compounds containing these metals are preferable, and bismuth-based compounds and antimony-based compounds are more preferable.

Bismuth-based compounds include bismuth oxide; bismuth nitrate such as bismuth nitrate and bismuth oxynitrate; bismuth halide such as bismuth chloride; bismuth oxychloride; bismuth sulfate; Bismuth subcarbonate and the like can be mentioned. Among these, bismuth hydroxide, bismuth oxide, bismuth subcarbonate and bismuth nitrate are preferred.
Examples of antimony-based compounds include antimony oxide, and more specifically, antimony-doped tin oxide obtained by doping tin oxide with antimony oxide.

The content of the color former is preferably 0.3 to 20% by mass, more preferably 0.5 to 10% by mass, more preferably 0.7 to 5% by mass, based on the total solid content of the background layer. more preferably 0.8 to 3% by mass.
By setting the content of the coloring agent to 0.3% by mass or more, the coloring property of the background layer can be easily enhanced. In addition, by setting the content of the coloring agent to 20% by mass or less, it is possible to easily increase the interlayer adhesion between the base color layer and the layer in contact with the base color layer, and the base color layer is colored due to the coloring agent. You can suppress having taste.
When the ground color layer is composed of two or more layers, the content of the coloring agent mentioned above means the content in each layer containing the coloring agent. For example, when the first background layer contains a color former and the second background layer does not contain a color former, the ratio of the color former to the total solids of the first and second background layers is It does not mean the content, but the content of the color former relative to the solid content of the first background layer.

The ground color layer may contain a coloring agent to adjust the color of the ground color layer.
Coloring agents contained in the background layer are general-purpose dyes and pigments (for example, inorganic pigments such as yellow lead, titanium yellow, red iron oxide, cadmium red, ultramarine, cobalt blue, titanium oxide, zinc oxide, quinacridone red, isoind Organic pigments or dyes such as linon yellow, phthalocyanine blue, etc.) can be used.
When the ground color layer is formed of two or more layers, at least one of the ground color layers may contain a coloring agent. A colorant is preferably contained in the color layer.
The content of the coloring agent in the ground color layer is preferably 0.1 to 50% by mass, more preferably 0.5 to 40% by mass, more preferably 0.7 to 0.7% by mass of the total solid content of the ground color layer. More preferably, it is 20% by mass.

The ground color layer 3 may be formed from two or more layers. For example, the ground layer 3 may have a first ground layer 3a and a second ground layer 3b, as shown in FIG.

The background layer 3 includes a first background color layer 3a containing a color former and a second background color layer 3b which is arranged on the inner layer side of the first background color layer and does not substantially contain a color former. It is preferable to have By configuring the base color layer in such a manner, the color development property of the first base color layer 3a is improved, higher-density printing becomes possible, and the L ^* value and hiding property are improved by the second base color layer 3b. can be enhanced.
In the present specification, the second ground color layer substantially does not contain a color former means that the content of the color former is 0.1% by mass or less of the total solid content of the second ground color layer. preferably 0.01% by mass or less, more preferably 0% by mass.

The thickness of the background layer is preferably 0.5 to 10.0 μm, more preferably 0.7 to 7.0 μm, even more preferably 1.0 to 5.0 μm.
By setting the thickness of the ground color layer to 0.5 μm or more, the color developability of the ground color layer can be easily enhanced. Also, by setting the thickness of the ground color layer to 10.0 μm or less, it is possible to reduce the damage to the packaging material caused by the laser, and to prevent the packaging material from becoming too thick and reducing workability.
When the ground color layer is composed of two or more layers, the thickness of each layer is preferably within the range described above.

<Sealant layer>
The surface of the sealant layer 4 on the inner layer side comes into direct contact with the object to be packaged, and plays a role of protecting the object to be packaged. In particular, when the packaging material 1 forms a packaging container for a liquid, the sealant layer 4 is preferably made of a material that does not allow the liquid to permeate. Moreover, it is preferable that the innermost layer of the sealant layer 4 has heat sealability for pouching.

Examples of materials constituting the sealant layer include polyethylene such as low density PE (LDPE), linear low density PE (LLDPE), medium density PE (MDPE) and high density PE (HDPE), ethylene-vinyl acetate polymers, vinyl chloride-based resins such as vinyl chloride-vinyl acetate copolymers, polyolefin-based resins such as propylene homopolymers, ethylene-propylene block copolymers, ethylene-propylene random copolymers; One or two or more of these resins can be used.
The sealant layer may be composed of a single layer or multiple layers of two or more layers. The sealant layer is a non-stretched film made of the resin described above, or a coating film obtained by applying an ink obtained by diluting the resin with a solvent and drying it, in order to suppress shrinkage during heat sealing. is preferred.

From the viewpoint of heating in a microwave oven and retort processing, the sealant layer is preferably made of a resin having excellent heat resistance in order to increase heat resistance. Specifically, propylene homopolymer, ethylene-propylene block copolymer Propylene-based resins such as coalesced, ethylene-propylene random copolymers, and HDPE are preferred.
Moreover, it is preferable to use the propylene-based resin properly according to the purpose. Specifically, ethylene-propylene block copolymers are preferred when cold resistance is emphasized (for example, packaging materials for frozen foods), and ethylene-propylene random copolymers are preferred when transparency is emphasized. Propylene homopolymer is preferable when the property is important. Further, in the case of a container equipped with an automatic vaporization mechanism, an ethylene-propylene block copolymer is preferable from the viewpoint that vapor can be easily escaped by reducing the sealing strength at high temperatures.

Moreover, when the lid of the lidded container is formed from the packaging material, the sealant layer preferably has easy peelability.
For example, when the sealant layer of the packaging material of the lid of the lidded container is bonded to the container body, the easy peel property means that the lid can be easily peeled off from the container body when the lidded container is opened. .
The sealant layer having easy peelability uses two or more resins, one resin (resin having good adhesion to the container body) and another resin (not having good adhesion to the container body). It can be formed by mixing one resin and an incompatible resin). Such a resin varies depending on the material of the container, so it cannot be generalized. By forming a sealant layer from a resin mixed with one or more selected from PE, polybutene and polystyrene, which are resins (resins that do not have good adhesion to the container body and are incompatible with the first resin), Easy peelability can be imparted to PP containers.
The sealant layer may have a multi-layered structure, and the easy peel property may be imparted only to the side of the sealant layer that is joined to the container body (the innermost layer in the packaging material).

The thickness of the sealant layer is not particularly limited, and is appropriately set depending on the use of the packaging material and the type and properties of the object to be packaged, but it is usually preferably about 10 to 200 μm. In the case of pouches (especially retort pouches), the thickness of the sealant layer is more preferably 20 to 150 μm, still more preferably 30 to 100 μm. In the case of a container with a lid, the thickness of the sealant layer is more preferably 15-80 μm, more preferably 20-60 μm.

<Pattern layer>
The packaging material of the present invention may have a pattern layer.
The pattern layer can be formed, for example, between the plastic film and the background layer. Alternatively, the pattern layer can be formed so as to be parallel to the background color layer at the same position as the background color layer in the thickness direction of the packaging material. When forming the pattern layer between the plastic film and the background layer, it is preferable to form the pattern layer while avoiding the portion to be laser-marked.

The pattern layer may be any layer as long as it can be distinguished from the background layer, and can be formed, for example, from a pattern layer-forming ink containing a coloring agent and a binder resin.
Colorants for the pattern layer include general-purpose dyes and pigments (for example, inorganic pigments such as yellow lead, titanium yellow, red iron oxide, cadmium red, ultramarine blue, cobalt blue, titanium oxide, zinc oxide, quinacridone red, isoindolinone yellow, Organic pigments or dyes such as phthalocyanine blue) can be used.
The thickness of the pattern layer is not particularly limited, and is preferably about 1.0 to 5.0 μm, more preferably 1.0 to 3.0 μm.

<Gas barrier layer>
The packaging material of the present invention may have a gas barrier layer 5 . The gas barrier layer 5 can be formed, for example, between the background layer 3 and the sealant layer 4 .
The gas barrier layer plays a role of blocking permeation of oxygen, water vapor, etc. between the packaged item and the external environment. In addition, the gas barrier layer may further impart light shielding properties for blocking transmission of visible light, ultraviolet rays, and the like. The gas barrier layer may be composed of only one layer, or may be composed of two or more layers. A gas barrier layer may be formed on an intermediate substrate, which will be described later.

A vapor deposition film and a coating film are mentioned as a gas barrier layer. The surface on which the gas barrier layer is to be formed may be previously surface-treated from the viewpoint of improving the adhesion of the gas barrier layer. Examples of the surface treatment include corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas, nitrogen gas, glow discharge treatment, oxidant treatment, application of an anchor coating agent, and the like.
From the viewpoint of increasing the L ^* value, the gas barrier layer is preferably a deposited film or a coated film.

[Deposition film]
Vapor-deposited films, which are examples of gas barrier layers, include, for example, silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B ), inorganic substances such as titanium (Ti), lead (Pb), zirconium (Zr), yttrium (Y), or oxides thereof as raw materials, physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, It can be formed by a chemical vapor deposition (CVD) method such as plasma chemical vapor deposition, thermal chemical vapor deposition, photochemical vapor deposition, or the like.
When the packaging material is for microwave ovens, inorganic oxides such as silicon oxides, aluminum oxides, and magnesium oxides are used from the viewpoint of enabling the food, etc. to be packaged to be sufficiently heated by the microwaves of microwave ovens. It is preferable to use a substance as a raw material.

The film thickness of the deposited film varies depending on the forming material, the required gas barrier performance, etc., but is generally preferably about 5 to 200 nm, more preferably 5 to 150 nm, further preferably 10 to 100 nm. In the case of inorganic oxides such as silicon oxides and aluminum oxides, the thickness is preferably about 5 to 100 nm, more preferably 5 to 50 nm, still more preferably 10 to 30 nm.

[Gas barrier coating film]
A gas barrier coating film, ^which is an ^example of a gas barrier layer _, ^may be represented by the general _formula ^: n is an integer of 0 or more, m is an integer of 1 or more, and n+m is the valence of M.) and at least one or more alkoxides represented by ), a polyvinyl alcohol resin and/or ethylene-vinyl A coating solution obtained by polycondensing an alcohol copolymer by a sol-gel method in the presence of a sol-gel method catalyst, acid, water and an organic solvent is applied, and the temperature is reduced to 0 at 50 to 300 ° C. It can be formed by heat treatment for 0.05 to 60 minutes.
Examples of the coating method include roll coating such as a gravure roll coater, spray coating, spin coating, dipping, brush coating, bar coating, and coating means such as an applicator. It is preferable that the dry film thickness of the coated film is about 0.01 to 30 μm, more preferably 0.05 to 20 μm, and still more preferably 0.1 to 10 μm by coating once or multiple times.
From the viewpoint of improving gas barrier properties, the gas barrier coating film is preferably formed on the surface of the deposited film.

<Intermediate base material layer>
The intermediate base material layer is used as necessary for the purpose of improving the strength of the packaging material 1, improving the processability, changing the texture of the packaging material, or using it as a base material for forming other layers. It is a layer provided Examples of the constituent material of the intermediate base material layer include plastic films and paper.
In the case of a plastic film, the same plastic film as described above formed on the outer layer side of the background layer 3 can be used.
In the case of paper, the packaging material 1 can be imparted with properties such as formability, bending resistance, and rigidity. processed paper or the like can be used. The basis weight of the paper is preferably about 50-600 g/m ² , more preferably 60-500 g/m ² , still more preferably 70-450 g/m ² . When the packaging material 1 is used for flexible packaging, it is preferably less than 150 g/m ² , and when used for paper containers such as paper cups and paper containers for liquids, it is preferably 200 g/m ² or more.

In consideration of heating in a microwave oven and retort treatment, the intermediate base material layer preferably has excellent heat resistance in order to increase the heat resistance of the packaging material. Specific examples of the intermediate substrate layer having excellent heat resistance include paper and various plastic films exemplified as plastic films having excellent heat resistance.

<Adhesive layer>
In the packaging material 1, each component layer may be laminated via an adhesive layer 6 from the viewpoint of improving the interlayer adhesive strength between each layer. The adhesive layer can be formed by a method using a known dry lamination adhesive or hot melt adhesive, and the dry lamination adhesive is preferable from the viewpoint of interlayer adhesion.

Dry laminate adhesives include, for example, polyether adhesives, polyvinyl acetate adhesives, polyacrylic acid ester adhesives, cyanoacrylate adhesives, ethylene copolymer adhesives, cellulose adhesives, polyester -based adhesives, polyamide-based adhesives, polyimide-based adhesives, amino resin-based adhesives such as urea resins and melamine resins, phenolic resin-based adhesives, epoxy-based adhesives, polyurethane-based adhesives (for example, polyol and isocyanate compound cured products), reactive (meth)acrylic acid adhesives, rubber adhesives such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber, silicone adhesives, inorganic adhesives such as alkali metal silicates and low-melting glass. agents and the like.
The hot-melt adhesive includes the same resins as exemplified for the sealant layer.

When the adhesive layer is formed with an adhesive for dry lamination, it is preferable to form the adhesive layer on the side where the interlayer adhesion is desired to be improved. Specifically, in the case of forming an adhesive layer between the base color layer and the sealant layer, if it is desired to improve the interlayer adhesion between the base color layer and the adhesive layer, a dry laminate is applied to the base color layer side. It is preferable to apply and dry an adhesive for sealing to form an adhesive layer, and laminate a sealant layer on the adhesive layer.

<Thermosoftening resin layer>
As shown in FIG. 6, the packaging material 1 may have a thermosoftening resin layer 7 in a partial region between the plastic film and the sealant layer.
As shown in FIG. 6, the heat-softening resin layer 7 is formed in a part near the edge of the packaging material 1, and the heat-softening resin layer has a predetermined strength in a temperature environment below room temperature. , By making it from a resin whose predetermined strength decreases in a high temperature environment, when it is heated in a microwave oven and the pressure inside the packaging container rises, part of the sealant layer breaks and the heat softening resin Some of the layers interfacially delaminate or cohesively fail, allowing vapor to escape. Details will be described in the second embodiment of the automatic vaporization mechanism.

A thermosoftening resin, that is, a resin that has a predetermined strength in a temperature environment of room temperature or lower but decreases in a predetermined strength in a high temperature environment, has a melting point of 60 to 110°C, preferably a melting point of 60 to 90°C. Specific examples include ethylene-vinyl acetate copolymer resins, polyamide, nitrocellulose and polyethylene wax, and mixed resins of polyamide, nitrocellulose and polyethylene wax are preferred. As the resin containing polyamide, nitrocellulose, and polyethylene wax, MWOP varnish (softening point: 105° C.) manufactured by DIC Graphics Corporation can be used.

The thickness of the thermosoftening resin layer is preferably 1 to 5 μm. By setting the thickness of the thermosoftening resin layer to 1 μm or more, the thermosoftening resin layer and the sealant layer can be easily broken when heated in a microwave oven. Further, by setting the thickness of the thermosoftening resin layer to 5 μm or less, when the film-like packaging material is wound into a roll, it is possible to suppress the expansion of the packaging material due to the occurrence of swelling in a part of the packaging material.

[Packaging container]
The packaging container of the present invention has, at least in part, the packaging material of the present invention described above.
By forming at least a part of the packaging container from the packaging material of the present invention, it is possible to obtain a packaging container capable of suppressing blurring of marked characters and improving the contrast of the characters.
At least a portion of the packaging container includes, for example, the entire container body 31, a portion of the container body 31, the entire lid 33, and a portion of the lid 33 in the case of the lidded container of FIG. Although not shown, at least part of the packaging container includes all or part of a label to be attached to the container body or the like.
The packaging material of the present invention may be applied to a desired portion of the packaging container to be laser-marked. of packaging material may be used.

Types of packaging containers include pouches, lidded containers, cups and trays.
Further, applications of packaging containers include food containers and cosmetic containers.
Moreover, the contents to be enclosed in the packaging container may be any of liquid, solid and gas.

A specific shape of the pouch is, for example, the shape of a pouch for a microwave oven shown in FIG. 3, which will be described later. The pouch may be a retort container (a container that has been sterilized at high temperature and high pressure), or may be a packaging container for microwave ovens or a container other than a retort container.
As a specific shape of the container with a lid, it has a configuration including a container body having an accommodating portion and a lid joined to the container body so as to seal the accommodating portion, and the lid is the Examples include those formed of packaging materials.
The packaging container can be suitably used for microwave ovens as described above. The packaging container can also be used as a retort container. Of course, the packaging container can also be used as a retort container for microwave ovens.

Specific layer structures of the pouch include any one of the layer structures (1) to (4) described above, and more specifically, the layer structures (A1) to (A2) below.
(A1) Plastic film/underground layer/adhesive layer/gas barrier layer/adhesive layer/sealant layer (A2) Plastic film/underground layer/adhesive layer/gas barrier layer/adhesive layer/intermediate substrate/sealant layer In (A1) and (A2) above, the plastic film is preferably a polyester film, the gas barrier layer is preferably a vapor deposition film, and the sealant layer is preferably non-stretched polypropylene (CPP) and low density PE (LDPE). In (A2) above, the intermediate substrate is preferably oriented nylon.

(pouch)
FIG. 3 shows an example of a pouch, which is one embodiment of the packaging container of the present invention. The pouch 10 shown in FIG. 3 is for a microwave oven, and is a standing pouch formed by heat-sealing a body portion 11 and a bottom portion 12 . As shown in FIG. 3, the body portion 11 includes a pair of principal sheets 13 composed of a front principal sheet 13a and a back principal sheet 13b which are arranged to face each other, and the pair of principal surfaces are overlapped. The sheets 13 are heat-sealed to each other near the side edges 14 . A bottom sheet 16 forming the bottom 12 is arranged between the lower edges 15 of the pair of main sheets 13 .
A storage space 17 for storing contents is formed in a region surrounded by the pair of main sheet 13 and bottom sheet 16 . The bottom sheet 16 is bent in a convex shape toward the accommodation space 17 side, and the vicinity of the peripheral edge thereof is heat-sealed together with the overlapping lower part of the main sheet 13 . Since the bottom sheet 16 retains the shape of the lower ends of the pair of main sheets 13, the pouch 10 can be made self-supporting and can be a standing pouch.
The pouch 10 of FIG. 3 has an opening 19 formed between the upper edges 18 of the front main sheet 13a and the back main sheet 13b, and contents can be stored through the opening 19. As shown in FIG. After containing the contents, the packaging container can be sealed by heat-sealing the vicinity of the upper edge 18 where the opening 19 is formed. When taking out the contents from the pouch 10, the notch 23 is opened by tearing the vicinity of the upper edge 18.例文帳に追加

The front main sheet 13 a , back main sheet 13 b and bottom sheet 16 of the pouch 10 can be formed from the packaging material 1 . All or part of these sheets can be formed from the packaging material 1 of the present invention. In FIG. 3, part of the front main sheet 13a has the ground color layer 3. As shown in FIG.

(automatic steaming mechanism)
If the container is for a microwave oven, when the pressure inside the pouch rises due to the steam generated by cooking the contents such as food, the steam inside the storage space is automatically released to the outside to prevent the pouch from bursting. It is preferable to have an automatic vaporization mechanism for The automatic steaming mechanism is preferably formed near the periphery of the container.

A first embodiment of the automatic steaming mechanism will be described with reference to FIG. The microwave pouch shown in FIG. 3 has a first unsealed region 21 that is not heat-sealed near the upper side edge 14 of the container (pouch). The first unsealed area 21 has an opening 22 down to the side edge 14 . Also, the first unsealed area 21 protrudes toward the housing space 17 . Further, the heat-sealed portion 25 protrudes toward the housing space 17 so as to surround the first unsealed region 21 that protrudes toward the housing space 17, forming a projecting portion 25a. More specifically, the first unsealed region 21 and the accommodation space 17 are separated from each other, and an overhanging portion 25a is formed so as to be continuous with the heat-sealing portion 25 for sealing the pouch. .
In the microwave pouch shown in FIG. 3, the opening 22, the first unsealed region 21, and the heat-sealed portion (overhanging portion 25a) projecting toward the accommodation space 17 form the automatic steaming mechanism 20. It is Specifically, when the pressure inside the container rises due to heating, the overhanging portion 25a of the heat-sealed portion 25 receives a strong load, and the overhanging region 25 peels off first. The space 17 and the first unsealed area 21 communicate with each other, allowing steam to escape to the outside.
Further details of the automatic vaporization mechanism of the type shown in FIG.

In addition, in the container 10 shown in FIG. 3 , a second unsealed area 23 is formed on the side edge 14 opposite to the first unsealed area 21 . The second unsealed area 23 is formed from the viewpoint of improving the yield of forming the openings 22 of the first unsealed area 21 when cutting one by one after forming a plurality of retort containers 10 continuously. and does not necessarily have to be formed.

A second embodiment of the automatic vaporization mechanism will be described with reference to FIGS. 6-8.
The packaging container (pouch) 10 shown in FIG. 7 is the edge of the packaging material shown in FIG. The periphery of the part is heat-sealed to form a pouch. 8 is a cross-sectional view of the heat-sealed portion 25 around the edge of the packaging container 10 of FIG. 7 taken along the line XI-XI.
As shown in FIG. 7, the heat-softening resin layer 7 is formed from the inner edge to the outer edge of the heat-sealed portion 25 for sealing the pouch in at least a partial region of the heat-sealed portion 25 of the packaging container 10. It is necessary that The strength of the thermosoftening resin layer 7 provided at such a position is lowered by being heated in a microwave oven to a high temperature.
As shown in FIG. 8, when the internal pressure of the thermosoftening resin layer 7 rises due to the expansion of the air in the packaging container 10 and the water vapor contained in the contents due to heating in a microwave oven, etc., the inner edge of the heat-sealed portion 25 is exposed. A portion of the sealant layer 4 is broken, and a portion of the thermosoftening resin layer 7 is interfacially peeled or cohesively broken starting from an arbitrary point "A" of the sealant layer 4 (the dashed line of symbol B indicates the sealant A virtual line where the layer 4 breaks and a virtual line where the thermosoftening resin layer 7 undergoes interfacial peeling or cohesive failure). As a result, air and water vapor are released from the broken portion, and the internal pressure of the packaging container 10 can be reduced.
The automatic steaming mechanism of the second embodiment can also be applied to a container with a lid, which will be described later.

As the packaging material that constitutes the container having the second embodiment of the automatic steaming mechanism, it is preferable to select a resin that easily collapses as the resin that constitutes the sealant layer. Specifically, LDPE is preferred.

(Container with lid)
4 and 5 show an example of an embodiment of the lidded container of the present invention. 4 is a top view, and FIG. 5 is a sectional view taken along line IV--IV of FIG. A lidded container 30 shown in FIGS. 4 and 5 includes a container body 32 in which a storage portion 31 is formed, and a lid 33 joined to the container body 32 so as to seal the storage portion 31 of the container body 32. ing. In FIG. 4, the shape of the container body 32 is substantially rectangular, but is not particularly limited. The container body 32 is not particularly limited in its molding method, and may be, for example, a tray molded by injection molding or a container formed by deep drawing.
In addition, since the material of the container body 32 is to be joined to the lid 33, it is usually thermoplastic resin such as PP or PET. PP is preferably used from the viewpoint of heat resistance and the like.
It is preferable that the lid 33 of the lidded container 30 is made of the packaging material 1 of the present invention.

The lid 33 has an easy peel property, as described in the description of the sealant layer 4 of the packaging material 1, from the viewpoint of facilitating the opening of the lidded container 30 by being peeled off from the container body 32. is preferred.
Specifically, the lid 33 and the container body 32 are joined together at a joint line 35 of the flange portion 34 of the container body 32 . The joining line 35 may be formed, for example, by heat-sealing the lid 33 and the flange portion 34, or may be formed by a separate component such as an adhesive layer.

When the lidded container 30 is used for a microwave oven, when the pressure in the lidded container 30 rises due to the steam generated by cooking the food or the like, which is the content contained in the container body 32, the lidded container 30 is heated. It is preferable to have an automatic vaporization mechanism (third embodiment of the automatic vaporization mechanism) that automatically releases the steam in the container 30 to the outside to prevent the lidded container 30 from bursting.
For example, the flange portion 34 has a protruding portion 34a that protrudes toward the center of the container body 32, and along this protruding portion 34a, the joint line 35 also protrudes toward the center of the container. It has a line 35a. Since the joint line 35 is formed in such a form, it becomes easier for the joint line 35 to separate from the projecting line 35a as the pressure inside the lidded container 30 rises due to heating. The housing portion 31 of 32 can be communicated with the outside, and the steam in the lidded container 30 can be released to the outside.
In the lidded container 30 shown in FIGS. 4 and 5, the protrusions 34a are formed on the opposite long sides of the flange 34, but two protrusions 34a are not necessarily formed. may

As the lid 33 constituting the lidded container 30, the packaging material shown in FIG. By using , steam can escape when heated in a microwave oven for the same reason as explained in the second embodiment of the automatic steaming mechanism.

<Lid body>
The lid of the present invention is at least partially formed of the packaging material of the present invention.
By forming at least a part of the lid with the packaging material of the present invention, a laser-markable lid with good contrast and suppressed bleeding can be obtained.

A specific layer structure of the packaging material that constitutes the lid includes any of the layered structures of (1) to (4) described above, and more specifically, the layered structure of (B1) below. .
(B1) Plastic film/underground layer/adhesive layer/gas barrier layer/adhesive layer/sealant layer The plastic film in (B1) above is preferably a polyester film, the gas barrier layer is preferably a vapor deposition film, and the sealant layer is LDPE or chloride. Vinyl chloride resins such as vinyl-vinyl acetate copolymers are preferred.

<label>
The label of the present invention is at least partially formed of the packaging material of the present invention.
By forming at least a part of the label from the packaging material of the present invention, a laser-markable label with good contrast and suppressed bleeding can be obtained.

A specific layer structure of the packaging material that constitutes the label includes any one of the layer structures (1) to (4) described above, and more specifically, the layer structure (C1) below.
(C1) Plastic Film/Background Layer/Adhesive Layer/Sealant Layer In (C1) above, the plastic film is preferably a polyester film, and the sealant layer is preferably an ethylene-vinyl acetate copolymer.

[Laser marking]
Laser beams used for laser marking include YAG (yttrium (Y), aluminum (A), garnet (G)) laser beam (wavelength = 1064 nm), YVO ₄ (yttrium vanadate) laser beam (wavelength = 1064 nm), fiber laser (1064 nm ), green laser (532 nm) and UV laser (355 nm) are preferred. These lasers can penetrate the outer thermoplastic resin layer and efficiently color the ground color layer.

The pulse conditions for laser marking include, for example, a YVO ₄ laser machine (trade name MD-V9600 manufactured by Keyence Corporation) with an average output of 0.8 to 5 W, more preferably 1.2 to 2 W, and a Q switch frequency of 10 to Pulse conditions of 30 KHz and scan speeds of 300-4000 mm/s, more preferably 1500-4000 mm/s are used. By performing laser marking under these conditions, high-speed printing is possible without causing great damage to the packaging material, and a clear printed image can be easily obtained.

The present disclosure includes the following [1] to [11].
[1] A packaging material having a configuration in which a plastic film, a background layer and a sealant layer are laminated in this order from the outer layer side, wherein the background layer contains titanium oxide and a binder resin, and the packaging material is The L ^* value of the CIE L ^* a ^* b ^* color system measured from the outer layer side is 90 or more, and the interlayer adhesion between the ground color layer and the layer in contact with the ground color layer is 0.5 N/15 mm or more. Yes, packaging.
[2] The packaging material according to [1], wherein the interlayer adhesive strength between the ground color layer and the layer in contact with the ground color layer is 1.0 N/15 mm or more.
[3] The packaging material according to [1] or [2], wherein the interlayer adhesive strength between the ground color layer and the layer in contact with the ground color layer is 1.4 to 4.0 N/15 mm.
[4] The packaging material according to any one of [1] to [3], wherein the background layer contains a coloring agent.
[5] The background color layer includes a first background color layer containing a color former, and a second background color layer that is disposed on the inner layer side of the first background color layer and does not substantially contain a color former. The packaging material according to any one of [1] to [4].
[6] The package according to [4] or [5], wherein the coloring agent is one or more selected from the group consisting of metals consisting of bismuth, antimony, copper and molybdenum, and compounds containing these metals. material.
[7] A packaging container at least partially comprising the packaging material according to any one of [1] to [6].
[8] The packaging container according to [7], wherein the packaging container is a pouch.
[9] A lidded container comprising a container body having an accommodating portion and a lid joined to the container body so as to seal the accommodating portion, wherein at least part of the lid is the packaging material. The packaging container according to [7], which is formed of
[10] A lid at least partly formed of the packaging material according to any one of [1] to [6].
[11] A label at least partially formed of the packaging material according to any one of [1] to [6].

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these.

1. Preparation of packaging material [Example 1]
One surface of a 20 μm thick oriented polypropylene film (OPP, melting point 165° C.) was subjected to corona treatment, and the treated surface was coated with a first ground color layer ink (1) having the following composition and dried to obtain a film having a thickness of 1.5 μm. A first ground color layer of 5 μm was formed.
Next, on the first background layer, a second background layer ink (1) having the following composition was applied and dried to form a second background layer having a thickness of 1.5 μm.
Next, on one side of a non-stretched polypropylene film (CPP) with a thickness of 30 μm, an adhesive layer ink containing a polyester resin containing a hydroxyl group and an isocyanate curing agent is applied, dried, and adhered to a thickness of 2.0 μm. An agent layer is formed, dry-laminated so that the adhesive layer and the second ground color layer face each other, and from the outer layer side, OPP (plastic film) / first ground color layer / second A packaging material of Example 1 was obtained, which had a laminate structure of background color layer/adhesive layer/CPP (sealant layer).

[Example 2]
One surface of a stretched nylon film (ONY, melting point: 215°C) having a thickness of 15 µm is subjected to corona treatment, and the treated surface is formed with a first ground color layer and a second ground color layer in the same manner as in Example 1. did.
Next, on one side of a low-density polyethylene film (LDPE) with a thickness of 60 μm, an adhesive layer ink containing a polyester resin containing a hydroxyl group and an isocyanate curing agent is applied, dried, and adhered to a thickness of 2.0 μm. An adhesive layer is formed, dry-laminated so that the adhesive layer and the second ground color layer face each other, and from the outer layer side, ONY (plastic film) / first ground color layer / second A packaging material of Example 2 having a laminate structure of background layer/adhesive layer/LDPE (sealant layer) was obtained.

[Example 3]
One surface of a stretched polyethylene terephthalate film (PET, melting point: 264°C) having a thickness of 12 µm was subjected to corona treatment, and the treated surface was provided with a first ground color layer and a second ground color layer in the same manner as in Example 1. formed.
Next, on one side of a low-density polyethylene film (LDPE) with a thickness of 60 μm, an adhesive layer ink containing a polyester resin containing a hydroxyl group and an isocyanate curing agent is applied, dried, and adhered to a thickness of 2.0 μm. An agent layer is formed, dry-laminated so that the adhesive layer and the second ground color layer face each other, and from the outer layer side, PET (plastic film) / first ground color layer / second A packaging material of Example 3 having a laminate structure of background layer/adhesive layer/LDPE (sealant layer) was obtained.

[Example 4]
One surface of a stretched polyethylene terephthalate film (PET, melting point: 264°C) having a thickness of 12 µm was subjected to corona treatment, and the treated surface was provided with a first ground color layer and a second ground color layer in the same manner as in Example 1. formed. Next, on the second background layer, an adhesive layer ink containing a polyester resin containing a hydroxyl group and an isocyanate curing agent is applied and dried to form an adhesive layer having a thickness of 2.0 μm, and laminated. Body A1 was obtained.
Next, one surface of a 15 μm thick stretched nylon film (ONY, melting point 215° C.) is subjected to corona treatment, and the treated surface is coated with an adhesive layer ink containing a hydroxyl group-containing polyester resin and an isocyanate curing agent. and dried to form an adhesive layer with a thickness of 2.0 μm. Next, a non-stretched polypropylene film (CPP) having a thickness of 30 μm was dry-laminated on the adhesive layer to obtain a laminate B1.
Next, the adhesive layer of the laminate A1 and the ONY of the laminate B1 are dry-laminated so as to face each other, and from the outer layer side, PET (plastic film) / first ground color layer / second ground color layer /adhesive layer/ONY (intermediate base material)/adhesive layer/CPP (sealant layer).

[Comparative Example 1]
One surface of a stretched polyethylene terephthalate film (PET, melting point: 264°C) having a thickness of 12 µm is subjected to corona treatment, and the treated surface is coated with a first ground color layer ink (2) having the following composition and dried to obtain a thickness of A first ground color layer of 1.5 μm was formed. Next, on the first ground color layer, a second ground color layer ink (2) having the following composition is applied and dried to form a second ground color layer having a thickness of 1.5 μm. got
On the other hand, on one side of a non-stretched polypropylene film (CPP) with a thickness of 70 μm, an adhesive layer ink containing a polyester resin containing a hydroxyl group and an isocyanate curing agent is applied, dried, and adhered to a thickness of 2.0 μm. An adhesive layer was formed, and an aluminum foil having a thickness of 7 μm was dry-laminated on the adhesive layer. Next, an adhesive layer ink containing a polyester resin containing a hydroxyl group and an isocyanate curing agent is applied onto the aluminum foil and dried to form an adhesive layer having a thickness of 2.0 μm to obtain a laminate B2. Ta.
Next, dry lamination is performed so that the second background color layer of the laminate A2 and the adhesive layer of the laminate B2 face each other, and from the outer layer side, PET (plastic film) / first background color layer / second A packaging material of Comparative Example 1 was obtained, which had a lamination structure of 2 background color layer/adhesive layer/aluminum foil/adhesive layer/CPP (sealant layer).

[Comparative Example 2]
A packaging material of Comparative Example 2 was obtained in the same manner as in Example 1, except that the first background layer ink (1) was changed to the following first background layer ink (3).

The composition of each ink is shown below.
<Ink for first background layer (1)>
・40 parts by mass of titanium oxide ・10 parts by mass of thermoplastic urethane resin containing hydroxyl group ・0.5 parts by mass of coloring agent (ATO particles) ・1 part by mass of additives such as anti-settling agents ・Appropriate amount of diluent solvent

<Ink for second background layer (1)>
・40 parts by mass of titanium oxide ・10 parts by mass of thermoplastic urethane resin containing hydroxyl group ・1 part by mass of additives such as anti-settling agent ・Appropriate amount of dilution solvent

<Ink for first background layer (2)>
・40 parts by mass of titanium oxide ・10 parts by mass of thermoplastic urethane resin containing hydroxyl group ・0.5 parts by mass of coloring agent (ATO particles) ・1 part by mass of isocyanate curing agent ・1 part by mass of additives such as anti-settling agents・Dilution solvent Appropriate amount

<Ink for second background layer (2)>
・40 parts by mass of titanium oxide ・10 parts by mass of thermoplastic urethane resin containing hydroxyl group ・1 part by mass of isocyanate curing agent ・1 part by mass of additives such as anti-settling agent ・Appropriate amount of diluent solvent

<Ink for first background layer (3)>
・40 parts by mass of titanium oxide ・10 parts by mass of thermoplastic urethane resin containing hydroxyl group ・2.0 parts by mass of coloring agent (ATO particles) ・1 part by mass of additives such as anti-settling agent ・Appropriate amount of dilution solvent

2. Measurement and evaluation 2-1. Interlayer Adhesion Strength The interlayer adhesion strength of the packaging material was measured. As a measuring instrument, a Tensilon universal material testing machine RTC-1310 manufactured by A&D was used. Specifically, a rectangular test piece was prepared by cutting out the packaging material and separating the plastic film and the sealant layer by 15 mm in the long side direction. The width (length of the short side) of the test piece was 15 mm. After that, the already peeled portion of the plastic film was gripped with one grip of the measuring device, and the sealant layer was gripped with the other grip of the measuring device. Then, the grippers are pulled in opposite directions to each other at a speed of 50 mm/min in a direction perpendicular to the surface direction of the portion where the plastic film and the sealant layer are still laminated, and the stable region (see FIG. 9) The average value of the tensile stress at was measured. The interval S between the grips when starting to pull was set to 30 mm, and the interval S between the grips when completing the pulling was set to 60 mm. FIG. 9 is a diagram showing changes in tensile stress with respect to the distance S between grips. As shown in FIG. 9, the change in tensile stress with respect to the interval S passes through the first region and enters the second region (stable region) where the rate of change is smaller than that of the first region. The average value of the tensile stress in the stable region was calculated for five specimens. Table 1 shows the results. Table 1 also shows the state of the peeled surface visually observed.
As described above, when the average value is 0.5 N/15 mm or more, it can be considered that the interlaminar adhesive strength between the base color layer and the layer in contact with the base color layer is 0.5 N/15 mm or more.

2-2. L ^* value White paper (white backing specified in ISO 13655) is placed on the inner layer side (sealant layer side) of the packaging materials of Examples and Comparative Examples, and light is incident at 5 degrees from the outer layer side (plastic film side). Then, the L ^* value of the specularly reflected light of the incident light in the Lab color system was measured. A spectrophotometer (manufactured by X-Rite, trade name: X-Rite eXact) was used as a measuring device. Table 1 shows the results.

2-3. Contrast and Bleeding The packaging materials of Examples and Comparative Examples were subjected to laser marking by irradiating a YVO ₄ laser beam from the plastic film side under the following conditions.
<Laser irradiation conditions>
Using YVO ₄ laser machine (trade name MD-V9600) manufactured by Keyence Corporation, average output 2.4 W, Q switch frequency 10 KHz, scan speed 2000 mm / s
<<Contrast>>
The contrast of the laser-marked print was visually evaluated. Evaluation was made by 20 subjects, with 3 points indicating good contrast, 2 points indicating neither, and 1 point indicating insufficient contrast. The average score of 20 evaluations was calculated and ranked according to the following criteria. Table 1 shows the results.
(Contrast evaluation criteria)
A: Average score of 2.5 or more B: Average score of 2.0 or more and less than 2.5 C: Average score of 1.5 or more and less than 2.0 D: Average score of less than 1.5 <<bleed>>
Bleeding at the laser-marked locations was visually evaluated. 3 points where it can be said that bleeding did not occur, 2 points where slight bleeding was observed but no problem in display quality, and 2 points where bleeding was observed in many places and there was a problem with display quality. was evaluated by 20 subjects as 1 point. The average score of 20 evaluations was calculated and ranked according to the following criteria. Table 1 shows the results.
(Bleeding Evaluation Criteria)
AA: Average score of 2.7 or more A: Average score of 2.5 or more and less than 2.7 B: Average score of 2.0 or more and less than 2.5 C: Average score of 1.5 or more and less than 2.0 D: Average score less than 1.5

From the results in Table 1, it can be confirmed that the packaging materials of Examples 1 to 4 can improve the contrast of letters and the like by laser marking and can suppress bleeding of the letters and the like.

REFERENCE SIGNS LIST 1 packaging material 2 plastic film 3 background layer 3a first background layer 3b second background layer 4 sealant layer 5 gas barrier layer 7 thermosoftening resin layer 10 packaging container 11 body 12 bottom 13 main sheet 14 side Rim 15 Lower edge 16 Bottom sheet 17 Storage space 18 Upper edge 19 Opening 20 Automatic vaporization mechanism 21 First unsealed area 22 Opening 23 Second unsealed area 24 Notch 25 Heat-sealed part 25a Projecting part 30 Lid container 31 Storage Part 32 Container body 33 Lid body 34 Flange part 35 Joining line

Claims (12)

A packaging material having a configuration in which a plastic film, a ground color layer and a sealant layer are laminated in this order from the outer layer side, wherein the ground color layer contains titanium oxide and a binder resin, and the packaging material is laminated from the outer layer side The measured L ^* value in the CIE L ^* a ^* b ^* color system is 91.8 or more, and the interlayer adhesion between the ground color layer and the layer in contact with the ground color layer is 0.5 N/15 mm or more. , packaging materials. 2. The packaging material according to claim 1, wherein an interlayer adhesive strength between said ground color layer and a layer in contact with said ground color layer is 1.0 N/15 mm or more. 3. The packaging material according to claim 1, wherein the interlayer adhesive strength between the ground color layer and the layer in contact with the ground color layer is 1.4 to 4.0 N/15 mm. The packaging material according to any one of claims 1 to 3, wherein the background layer contains a coloring agent. The background color layer has a first background color layer containing a coloring agent and a second background color layer disposed on the inner layer side than the first background color layer,
The content of the color former in the second background layer is 0.1 mass% or less of the total solid content of the second background layer, according to any one of claims 1 to 4. packaging material. 6. The packaging material according to claim 4, wherein the coloring agent is one or more selected from the group consisting of metals consisting of bismuth, antimony, copper and molybdenum, and compounds containing these metals. The packaging material according to any one of claims 1 to 6, wherein the plastic film is a polyester-based resin or a polyamide-based resin. A packaging container at least partially comprising the packaging material according to any one of claims 1 to 7. 9. The packaging container according to claim 8, wherein said packaging container is a pouch. A lidded container comprising a container body having an accommodating portion and a lid joined to the container body so as to seal the accommodating portion, wherein at least part of the lid is formed of the packaging material. The packaging container according to claim 8, wherein the packaging container is A lid, at least a part of which is formed of the packaging material according to any one of claims 1 to 7. A label at least partially formed of the packaging material according to any one of claims 1 to 7.