LASER-PRINTED PACKAGING

TECHNICAL FIELD

The present invention relates to packaging printed by laser.

BACKGROUND ART

Conventionally, packaging made of plastic films has widely used for distribution goods typified by foods, medicines and industrial products. For the most part, such packaging not only protects the contents but also has the role of displaying (hereinafter sometimes referred to as “printing”) information pertaining to the product name, manufacturing date, raw materials, and so forth. In recent years, packaging printed by laser has been disclosed, for example, as described in Patent Document 1. In this technology, a laser printing function is realized by applying (coating) an ink layer containing a coloring material (pigment) that reacts to the laser onto a film that serves as a substrate. However, as described in Non-Patent Document 1, coating with a laser-printable pigment may decrease the lamination strength of the coated surface. In general, packaging is required to have a plurality of functions such as sealing strength and mechanical strength in addition to the above-described display function, and accordingly, a plurality of films are employed. Lamination is widely employed when a plurality of films are laminated, and the use of laser pigments may cause peeling off (delamination) of the laminated portion. Patent Document 1 does not mention a method for ensuring lamination strength when laser pigments are used.

Patent Document 2, like Patent Document 1, is a technology related to packaging that is coated with a laser pigment and has a laser printing function, and discloses that both laser printing performance and delamination suppression can be achieved by designing the lamination strength between the print layer and the sealant layer to be higher (for example, 3.8 N/15 mm or more) than the lamination strength (1.8 to 3.5 N/15 mm) between the print layer (layer containing laser pigment) and the substrate layer. However, generally decreasing the lamination strength (intentionally) means diminishing the performance as packaging, and there is a problem that this method cannot be used for applications requiring high lamination strength. Furthermore, it is complicated to control the lamination strength between the respective layers as in Patent Document 2, the degree of freedom of packaging has sometimes been limited in view of the fact that a wide variety of high-quality items are required for packaging in recent years.

In Patent Document 2, the content of the resin component in the white ink constituting the laser printing layer is as low as 50% by weight or less, and it is disclosed that it is difficult to form a discolored region by laser light irradiation when the amount of resin component is larger than this. A small amount of the resin component means a large amount of the laser pigment and the like, and this leads to an increase in cost.

For example, in the case of using the above-described laser pigment coating technology as a display means on the packaging, the region where the ink layer containing a laser pigment is formed is often limited to only a part of the packaging rather than the whole packaging. This is because coating the whole packaging with a laser pigment leads not only to the above-described delamination but also to reduction in productivity and an increase in cost. However, coating only a part of the packaging with a laser pigment causes a new problem of impairing the design of the packaging. This is because the color tone changes only at the part coated with a laser pigment since titanium oxide and carbon black, which are widely used as laser pigments, are white or black in color. In other words, the present situation is that packaging employing laser printing technology cannot satisfy all of the quality, productivity/economic efficiency, and design.

PRIOR ART DOCUMENTS
Patent Documents

Patent Document 1: JP-A-2019-214392

Patent Document 2: JP-B-6268873

Non-Patent Document

Non-Patent Document 1: Masao Gobe and 2 others, “Effect of Pigments on Lamination Strength in Gravure Laminating Inks”, Shikizai, Vol. 64, No. 12, 1991

SUMMARY OF THE INVENTION
Problems to be Solved by Invention

It is an object of the present invention to solve problems of the conventional art such as the foregoing. In other words, an object of the present invention is to provide laser-printed packaging composed of a laminated body excellent in lamination strength and visual perceptibility of printed portions without using ink containing a laser pigment.

Means for Solving the Problems

The present invention is constituted as follows.

1. Packaging comprising a laminated body including a sealing layer and at least one laser printing layer that can undergo printing by laser irradiation, in which the laser printing layer includes a laser-printed portion printed by laser and a non-printed portion, the sealing layer is at least an innermost layer, at least a part of the sealing layers of the innermost layers are pasted to each other, and the packaging meets the following requirements of (1) to (3):

- (1) a difference in color L* value between the laser-printed portion and the non-printed portion is 1.0 or more and 10 or less;
- (2) adhesive strength between the sealing layers is 2 N/15 mm or more and 80 N/15 mm or less; and
- (3) lamination strength between the laser printing layer and a layer adjacent to at least one side of the laser printing layer is 2 N/15 mm or more and 10 N/15 mm or less.

2. The packaging according to 1., in which either a height or width of printing size in the laser-printed portion is 0.2 mm or more and 100 mm or less.

3. The packaging according to 1. or 2., in which the laser printing layer is provided over a whole region of a plane of the laminated body constituting the packaging.

4. The packaging according to any one of 1. to 3., in which the laser printing layer contains single substances or compounds of one or more selected from the group consisting of bismuth, gadolinium, neodymium, titanium, antimony, tin, aluminum, calcium, and barium as a laser printing pigment.

5. The packaging according to any one of 1. to 4., in which a main resin constituting the laser printing layer is polyester, polypropylene, or polyethylene.

6. The packaging according to any one of 1. to 5., in which a content of a resin constituting the laser printing layer is more than 50% by mass and 99.95% by mass or less.

7. The packaging according to any one of 1. to 6., in which a substrate layer is further laminated in the laminated body.

8. The packaging according to any one of 1. to 7., in which a gas barrier layer is further laminated in the laminated body.

9. The packaging according to any one of 1. to 8., in which a thickness of the laser printing layer is 5 μm or more and 200 μm or less.

Effect of the Invention

According to the present invention, it is possible to provide packaging that satisfies the lamination strength without complicating the design of the packaging and is highly productive, economical, and well-designed.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, packaging of the present invention will be described.

1. Configuration of Packaging

1.1. Layer Configuration and Thickness

The packaging of the present invention is composed of a laminated body, and in the packaging, it is required that at least one layer is a film layer (laser printing layer) that can undergo printing by laser irradiation, the laser printing layer has a laser-printed portion printed by laser and a non-printed portion, a sealing layer is at least the innermost layer, and at least a part of the sealing layers of the innermost layers are pasted to each other. From the gist that the present invention can be established when the design of the packaging material is simplified as well, a preferred embodiment is that the laminated body constituting the packaging has a laser printing layer over the whole region (in the plane direction). In addition to the laser printing layer and the sealing layer, other layers may be laminated in the packaging of the present invention. The packaging of the present invention may be provided with a print layer on which characters and patterns other than the printing formed by laser are described in order to improve the design. Necessary or preferred requirements for these layers will be described later.

As preferred layer configuration of the present invention, the following configuration may be exemplified. Below, lamination may be described simply as “lami.” “Lami” and “sealing” have essentially the same meaning “pasting”, but in the present invention, it is described as “lami” when each layer is laminated and it is described as “sealing” when the packaging is sealed (the innermost layers of the laminated body are partially pasted to each other) for distinguishment.

(Outer side) printing layer/print layer/lami layer/sealing layer (inner side)

(Outer side) substrate layer/print layer/substrate layer/lami layer/printing layer/lami layer/sealing layer (inner side)

(Outer side) substrate layer/print layer/transparent gas barrier layer/lami layer/printing layer/lami layer/sealing layer (inner side)

(Outer side) substrate layer/lami layer/printing layer/opaque gas barrier layer (metal foil)/lami layer/sealing layer (inner side)

The packaging of the present invention may be further provided with an anchor coat layer laminated on the substrate layer or adhesive layer and an overcoat layer laminated on the gas barrier layer, if necessary. By providing these layers, the gas barrier properties and scratch resistance of the packaging can be improved.

The thickness of the packaging is not particularly limited, but is preferably 5 μm or more and 500 μm or less. It is not preferred that the thickness of the packaging is thinner than 5 μm since the mechanical strength and heat sealing strength may be insufficient. The thickness of the packaging may be thicker than 500 μm, but this is not preferred since the cost of the materials used (films and lamination materials) increases accordingly. The thickness of the packaging is more preferably 10 μm or more and 495 μm or less, still more preferably 15 μm or more and 490 μm or less.

The thickness of the printing layer constituting the laminated body of the present invention is preferably 3 μm or more and 190 μm or less. When the thickness is less than 3 μm, the visual perceptibility of laser printing may be diminished even when the concentration of the laser printing pigment described later is increased. When the thickness of the printing layer exceeds 190 μm, the volume of the film that absorbs the laser is extremely large, this may cause great damage, and deformation or perforation of the laminated body may occur. The thickness of the printing layer is more preferably 10 μm or more and 180 μm or less, still more preferably 15 μm or more and 170 μm or less.

In order to improve properties such as printability and lubricity of the surface, all the layers constituting the packaging of the present invention can be provided with layers subjected to corona treatment, coating treatment, flame treatment, and the like, and these layers can be provided arbitrarily within the scope of the requirements of the present invention.

1.2. Laser Printing Layer

1.2.1. Types of Laser Printing Pigments, Amounts Thereof Added, and Methods for Adding Same

So that a printing layer making up the present invention may be made laser-printable, laser printing pigment having functionality permitting change in color when acted on by laser irradiation must be added thereto. Since it is ordinarily the case that the plastic which makes up the laminated body will itself have almost no reaction to laser light, it is incapable of permitting printing by means of laser irradiation. Laser printing pigment can be made to undergo excitation by the energy from laser light, making it possible for printing to take place as a result of carburization of the surrounding plastic. Furthermore, besides the plastic carburization effect, there are laser printing pigments which, depending on the type thereof, may themselves change color and become black. Simple or complex action of this carburization effect and/or laser printing pigment color change effect makes it possible for printing to be carried out at the printing layer. From the standpoint of printing density, it is preferred that laser printing pigment(s) having both the plastic carburization effect and the effect whereby it itself changes color be selected.

As specific types of laser printing pigments, any of bismuth, gadolinium, neodymium, titanium, antimony, tin, aluminum, calcium, and barium-whether present alone or in oxide form—may be cited. Among these, titanium oxide, calcium carbonate, bismuth trioxide, antimony trioxide, and barium sulfate are preferred, and titanium oxide, calcium carbonate and bismuth trioxide are more preferred. Furthermore, it is preferred that laser printing pigment particle diameter be 0.1 μm or more and 10 μm or less. When laser printing pigment particle diameter is less than 0.1 μm, there is a possibility that change in color when irradiated by a laser will no longer be adequate. When the particle size of the laser printing pigment exceeds 10 μm, there is a concern that clogging of the filter is accelerated in the extrusion process when a film is formed. It is more preferred that laser printing pigment particle diameter be 1 μm or more and 9 μm or less, and still more preferred that this be 2 μm or more and 8 μm or less.

The amount of the laser printing pigment added to the laser printing layer is preferably 0.05% by mass or more and 50% by mass or less. When the amount of pigment added is less than 0.05% by mass, this is not preferred since the printing density produced by the laser will no longer be adequate. When the amount of pigment added exceeds 50% by mass, the amount (volume) of carbonized plastic is relatively decreased, and this may also result in insufficient printing density. The amount of laser printing pigment added is more preferably 0.1% by mass or more and 49% by mass or less, still more preferably 0.15% by mass or more and 48% by mass or less, particularly preferably 0.2% by mass or more and 47% by mass or less. In a case where the laser printing layer is multiple layers, the amount of the laser printing pigment added to all the laser printing layers can be determined by proportionally dividing the thickness ratio among the respective layers and the amount of the laser printing pigment added.

As the method for blending the laser printing pigment, the laser printing pigment can be added at any stage during the manufacture of the resin to be a raw material for the laser printing layer or the film to be the laser printing layer. For example, with regard to step(s) during manufacture of resin(s), methods in which a vented kneader extruder is used to cause plastic raw material and a slurry in which particles thereof are dispersed in solvent to be blended, methods in which a kneader extruder is used to cause dried particles thereof and plastic resin to be blended (made into masterbatch), and so forth may also be cited. Among these, methods in which masterbatch that contains laser printing pigment is used as film raw material are preferred.

1.2.2. Types of Plastic

The type of plastic constituting the laser printing layer of the present invention is not particularly limited, and any type of plastic can be freely used without departing from the gist of the present invention. As the type of plastic (resin), polyester, polyolefin, polyamide, and the like may be cited as examples.

As polyester, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polytrimethylene terephthalate (PTT), polybutylene naphthalate (PBN), polylactic acid (PLA), polyethylene furanoate (PEF), polybutylene succinate (PBS), and so forth may be cited as examples. Moreover, in addition to the polyesters cited at the foregoing examples, it is also possible to use modified polyesters in which the monomer(s) at such acid site and/or diol site are altered. As acid-site monomer, isophthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, orthophthalic acid, and other such aromatic dicarboxylic acids, adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, and other such aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids may be cited as examples. Furthermore, as diol-site monomer, neopentyl glycol, 1,4-cyclohexanedimethanol, diethylene glycol, 2,2-diethyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-isopropyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, hexanediol, 1,4-butanediol, and other such long-chain diols, hexanediol and other such aliphatic diols, bisphenol A and other such aromatic-type diols, and so forth may be cited as examples. Moreover, as component making up polyester, this may include polyester elastomer(s) comprising ε-caprolactone, tetramethylene glycol, and/or the like. Regarding the polyester raw materials cited above, it is possible to use raw material in which a plurality of types of homopolyester, each of which has polymerized therein one types of carboxylic acid monomer and one types of diol monomer, are mixed (dry blended); and it is possible to use raw material in which two or more types of carboxylic acid monomer and/or two or more types of diol monomer are copolymerized. Furthermore, it is possible to use raw material in which homopolyester(s) and copolymerized polyester(s) are mixed.

While there is no particular limitation with respect to the intrinsic viscosity (IV) of polyester serving as raw material, it being possible for this be freely chosen as desired, it is preferred that this be 0.5 dL/g to 1.2 dL/g. When IV is less than 0.5 dL/g, since this causes molecular weight of the raw material to be too low, this will increase the tendency for fracture to occur during film formation, and increases the tendency for tensile fracture strength of the display body to fall below 40 MPa, and for other such problems to occur. On the other hand, when IV exceeds 1.2 dL/g, this is not preferred, since it will cause the resin pressure at the time of extruding operation(s) during film formation to be too high, which would tend to cause occurrence of deformation of filter(s) and so forth. It is more preferred that IV be 0.55 dL/g or more and 1.15 dL/g or less, and still more preferred that this be 0.6 dL/g or more and 1.1 dL/g or less.

As polyolefin, polypropylene (PP), polyethylene (PE), and so forth may be cited as examples. Where polypropylene is employed, there is no particular limitation with respect to stereoregularity, it being possible for this to be isotactic, syndiotactic, and/or atactic, it being possible for these to be present therein in any desired fractional percentage(s). Furthermore, where polyethylene is employed, there is no particular limitation with respect to the density (degree of branching) thereof, it being possible for this to be high density (HDPE), linear low density (LLDPE), and/or low density (LDPE). Furthermore, besides the foregoing homopolymers, raw materials in which two or more different types of monomers are copolymerized may be used; examples of monomers that may be used for copolymerization which may be cited including ethylene, α-olefins, and so forth; examples of α-olefins which may be cited including propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 4-methyl-1-pentene, 4-methyl-1-hexene, and so forth. The type of copolymerization may be random copolymerization and/or block copolymerization. Moreover, besides the examples of raw materials cited above, polyolefin elastomer and/or ionomer may be employed.

While there is no particular limitation with respect to the melt flow rate (MFR) of polyolefin serving as raw material, it being possible for this be freely chosen as desired, it is preferred that this be 1 g/10 min to 10 g/10 min. When MFR is less than 1 g/10 min, this is not preferred since it would cause the melt viscosity of the raw material to be too high, as a result of which the resin pressure at the time of extruding operation(s) during film formation would be too high, which would tend to cause occurrence of deformation of filter(s) and so forth. On the other hand, when MFR exceeds 10 g/10 min, since this would cause molecular weight to become extremely low, there is a possibility that it would increase the tendency for fracture to occur during film formation, and/or that it would reduce resistance to blocking. It is more preferred that MFR be 2 g/10 min or more and 8 g/10 min, and still more preferred that this be 3 g/10 min or more and 7 g/10 min.

As polyamide, any one type of resin—or a raw material mixture in which two or more types thereof are mixed—selected from among polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), caprolactam/lauryl lactam copolymer (nylon 6/12), caprolactam/hexamethylene diammonium adipate copolymer (nylon 6/66), ethylene ammonium adipate/hexamethylene diammonium adipate/hexamethylene diammonium sebacate copolymer (nylon 6/66/610), polymers of meta-xylylenediamine and adipic acid (MXD-6), hexamethylene isophthalamide/terephthalamide copolymer (amorphous nylon), and so forth may be cited as examples. Furthermore, an adhesion improvement layer may be provided at the surface of a film comprising any of the examples of plastics cited above. As material for the adhesion improvement layer, acrylic, a water-soluble or water-dispersible polyester, a hydrophobic polyester in which acrylic is graft copolymerized, and so forth may be cited as examples.

It is preferred that the relative viscosity (RV) of polyamide serving as raw material be 2.2 or more and 4 or less. When RV is less than 2.2, crystallization rate may be too high, and there may be a tendency for fracture or the like to occur when stretching is carried out during film forming operations. On the other hand, when RV exceeds 4, this is not preferred, as the load on the extruder will be too high, and there will be increased tendency for occurrence of filter deformation and the like. It is more preferred that RV be 2.3 or more and 3.9 or less, and still more preferred that this be 2.4 or more and 3.8 or less. The “relative viscosity” in the context of the present invention means the value measured at 25° C. using a solution in which 0.5 g of polymer has been dissolved in 50 ml of 97.5% sulfuric acid.

As the type of plastic constituting the laser printing layer, polyester, polypropylene, and polyethylene are preferred among those cited above from the viewpoint of mechanical strength, film forming stability, and laser printing performance.

The content of the plastic constituting the laser printing layer is preferably more than 50% by mass and 99.95% by mass or less. It is not preferred that the plastic content is less than 50% by mass since the tensile fracture strength, which will be described later, may be likely to be less than 40 MPa. It is not preferred that the plastic content exceeds 99.95% by mass since the content of laser printing pigment is relatively less than 0.05% by mass and the difference in color L* value between the printed portion and the non-printed portion is likely to be less than 1.0. The plastic content is more preferably 51% by mass or more and 99.9% by mass or less, still more preferably 52% by mass or more and 99.85% by mass, particularly preferably 53% by mass or more and 99.8% by mass or less. In a case where the laser printing layer is multiple layers, the plastic content in all the laser printing layers can be determined by proportionally dividing the thickness ratio among the respective layers and the plastic content.

1.2.3. Additives Other than Laser Printing Pigment

Any of various additives, e.g., waxes, antioxidants, anti-static agents, crystal nucleating agents, viscosity-lowering agents, thermal stabilizers, colorant pigments, antistaining agents, ultraviolet light absorbers, and/or the like, may be added as necessary within laser printing layer(s) making up the packaging of the present invention. Furthermore, where a laser printing layer is a surface most layer, it is preferred that microparticles serving as a lubricant for improving lubricity be added thereto. Any desired microparticles may be chosen. For example, as inorganic-type microparticles, silica, alumina, kaolin, white lead, titanium white, zeolite, zinc oxide, lithopone, and so forth may be cited; as organic-type microparticles, acrylic particles, melamine particles, silicone particles, crosslinked polystyrene particles, carbon black, iron oxide, and so forth may be cited. Average particle diameter of microparticles when measured by means of a Coulter counter may be chosen as appropriate as needed within the range 0.05 μm to 3.0 μm. It is preferred that the lower limit of the range in values for the fractional amount of microparticles present therein be 0.01% by mass, more preferred that this be 0.015% by mass, and still more preferred that this be 0.02% by mass. Below 0.01% by mass, there may be reduction in lubricity. It is preferred that the upper limit of the range in values be 1% by mass, more preferred that this be 0.2% by mass, and still more preferred that this be 0.1% by mass. It is not preferred that the upper limit exceeds 1% by mass since there may be problems such as reduction in smoothness of the surface and faint printability may occur.

As method for causing particles to be blended within the laser printing layer, these may be added at any desired step(s) during manufacture of the plastic raw material, and it is possible to adopt a method that is the same as at the foregoing “1.2.1. Types of Laser Printing Pigments, Amounts Thereof Added, and Methods for Adding Same”.

1.3. Sealing Layer

The sealing layer constituting the packaging of the present invention is not particularly limited as long as it exhibits adhesive properties, and conventionally known ones can be arbitrarily used without departing from the gist of the present invention. Examples thereof include a heat sealing layer that exerts adhesive properties by heat and a pressure sensitive adhesive (tacky) layer that exhibits adhesive properties at room temperature.

As the type of plastic that makes up the heat sealing layer, polyester, polyolefin, polyamide, and the like may be cited as examples.

It is preferred that the lower limit of the range in values for relative viscosity (RV) of polyamide serving as raw material be 2.2, and more preferred that this be 2.3. When the foregoing is less than this, crystallization rate may be too high and biaxial stretching may be difficult. On the other hand, it is preferred that the upper limit of the range in values for the RV of polyamide be 4, and more preferred that this be 3.9. When the foregoing is exceeded, there is a possibility that the load or the like on the extruder will become too high and/or that productivity will decrease. The “relative viscosity” in the context of the present invention means the value measured at 25° C. using a solution in which 0.5 g of polymer has been dissolved in 50 ml of 97.5% sulfuric acid.

As the type of plastic that makes up the pressure sensitive adhesive layer, polyester, polyolefin, polystyrene, acrylic resin, and the like may be cited as examples, those having a glass transition temperature Tg which is below room temperature (in the vicinity of 25° C.) being particularly preferred.

As examples of polyester, as monomer(s) that will permit Tg to be lowered, it is preferred that saturated carboxyl acid component and/or saturated diol component be used. As saturated carboxyl acid, adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and so forth may be cited. Among these, adipic acid and azelaic acid are preferred. As saturated diol component, ethylene glycol, diethylene glycol, 1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,4-butanediol, and other such long-chain diols, and hexanediol and other such aliphatic diols may be cited. Among these, use of diethylene glycol, 1,3-propanediol, and/or 1,4-butanediol is preferred. Moreover, as component making up polyester-type resin, polyester elastomer(s) comprising ε-caprolactone, tetramethylene glycol, and/or the like may be used. Polyester elastomer may be favorably used since it is effective in lowering Tg.

As polyolefin-based substances, polyolefin-based elastomers may be cited as examples. As polyolefin-based elastomers, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-propylene-1-butene copolymer, ethylene-propylene-1-hexene copolymer, ethylene-1-butene-1-hexene copolymer, propylene-1-butene copolymer, propylene-1-hexene copolymer, propylene-1-octene copolymer, propylene-4-methyl-1-pentene copolymer, propylene-1-butene-1-hexene copolymer, propylene-1-butene-4-methyl-1-pentene copolymer, and so forth may be cited as examples. Furthermore, small amount(s) of SBS, SEBS, and/or other such styrenic elastomer(s) may be added thereto.

As polystyrenes, polystyrenic elastomers may be cited as examples. As polystyrenic elastomers, polymers in which an aromatic alkenyl compound and a conjugated diene have been block copolymerized may be cited as examples; examples of aromatic alkenyl compounds which may be cited including styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, divinylbenzene, 1,1-diphenylethylene, vinylnaphthalene, vinylanthracene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene, vinylpyridine, and so forth; examples of conjugated diene monomers which may be cited including 1,3-butadiene, 1,2-butadiene, isoprene, 2,3-dimethyl-butadiene, 1,3-pentadiene, 2-methyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-cyclohexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, myrcene, chloroprene, and other such diolefins.

Acrylic resin may be a copolymer of acrylic monomer or a copolymer of acrylic monomer and a monomer other than that which is capable of being copolymerized. As acrylic monomer, such copolymer may be derived from monomers, examples of which that may be cited including (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl acrylate, n-butyl (meth)acrylate, isobutyl acrylate, t-butyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, decyl (meth)acrylate, octadecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and other such (meth)acrylic acid alkyl esters; cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, and other such (meth)acrylic acid cyclic esters; allyl (meth)acrylate, 1-methylallyl (meth)acrylate, 2-methylallyl (meth)acrylate, and other such vinyl (meth)acrylates and other such unsaturated-group-containing (meth)acrylic acid esters; glycidyl (meth)acrylate, (3,4-epoxycyclohexyl)methyl (meth)acrylate, and other such heterocycle-containing (meth)acrylic acid esters; N-methylaminoethyl (meth)acrylate, N-tributylaminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and other such amino-group containing (meth)acrylic acid esters; 3-methacryloxypropyltrimethoxysilane and other such alkoxysilyl-group-containing (meth)acrylic acid esters; methoxyethyl (meth)acrylate, ethylene oxide adduct of (meth)acrylic acid, and other such (meth)acrylic acid derivatives; perfluoroethyl (meth)acrylate, perfluorobutyl (meth)acrylate, and other such (meth)acrylic acid perfluoroalkyl esters; trimethylolpropane tri(meth)acrylate and other such polyfunctional (meth)acrylic acid esters; and so forth. Furthermore, as monomers other than acrylic that are capable of being copolymerized, as monomers having at least one carboxyl group at a radical polymerizable unsaturated group, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, and so forth may be cited as examples. Furthermore, besides radical polymerizable unsaturated groups, as monomers having at least one hydroxyl group, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, diethylene glycol mono(meth)acrylate, and so forth may be cited as examples. Moreover, as vinyl monomers and the like which are capable of copolymerization with acrylic monomer, styrene, α-styrene, and other such aromatic vinyl-type monomers; vinyltrimethoxysilane and other such trialkyloxysilyl-group-containing vinyl monomers; acrylonitrile, methacrylonitrile, and other such nitrile-group-containing vinyl-type monomers; acrylamide- and methacrylamide-group-containing vinyl-type monomers; vinyl acetate, vinyl versatate, and other such vinyl esters and so forth may be cited as examples.

Using plastic of any of the types described above by way of example as raw material, this may be used as desired as film formed so as to be unstretched, uniaxially stretched, or biaxially stretched, or as a coating in which this is dispersed in solvent or the like. In a case of forming a film, the film is preferably unstretched or uniaxially stretched, more preferably unstretched for achievement of sealing properties. In this case, the printing layer and the sealing layer may be laminated with an adhesive layer, which will be described later, interposed therebetween or the sealing layer may be laminated during the extrusion process when the printing layer is formed.

The thickness of the sealing layer constituting the laminated body of the present invention is preferably 2 μm or more and 190 μm or less. It is not preferred that the thickness of the sealing layer is less than 2 μm since the heat sealing strength of the laminated body decreases. It is not preferred that the thickness of the sealing layer exceeds 190 μm since the thickness of the printing layer is relatively decreased and the visual perceptibility of the printing is diminished although the heat sealing properties of the laminated body is improved. The thickness of the sealing layer is more preferably 3 μm or more and 180 μm or less, still more preferably 4 μm or more and 170 μm or less.

1.4. Laminating Agent

As a laminating agent that can be used when each layer of the packaging of the present invention is laminated, an adhesive for dry lamination or a resin layer formed by extrusion lamination can be used, and as described in the section on the effects of the invention, conventionally known ones can be arbitrarily employed. The adhesive may be either a one-pack type (drying type) or a two-pack type (curing reaction type). In the case of dry lamination, commercially available polyurethane-based and polyester-based adhesives for dry lamination can be used. Representative examples include Dicdry (registered trademark) LX-703VL manufactured by DIC Corporation; KR-90 manufactured by DIC Corporation; Takenate (registered trademark) A-4 manufactured by Mitsui Chemicals, Inc.; Takelac (registered trademark) A-905 manufactured by Mitsui Chemicals, Inc.; and so forth. In the case of extrusion lamination, a polyolefin-based resin such as polyethylene is melted between layers or between a layer and another layer for pasting, but it is also preferable to laminate an anchor coat layer in order to enhance the adhesive properties of the surface of the layer and the like.

In a case of laminating films with a laminating agent interposed therebetween, lamination is completed as the laminating agent is applied to either film, and then dried or reacted and cured. In the packaging of the present invention, the lamination layer thickness after drying is preferably 1 μm or more and 6 μm or less, more preferably 2 μm or more and 5 μm or less. It is not preferred that the lamination layer thickness after drying is less than 1 μm since the lamination strength is likely to be less than 2 N/15 mm. It is not preferred that the lamination layer thickness after drying exceeds 6 μm since the drying time required for curing the laminating agent is long and the productivity of the packaging decreases.

1.5. Substrate Layer

Examples of the type of plastic constituting the substrate layer that can be preferably included in the packaging of the present invention include polyester, polyolefin, and polyamide.

As polyamide, any one type of resin-or a raw material mixture in which two or more types thereof are mixed-selected from among polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), caprolactam/lauryl lactam copolymer (nylon 6/12), caprolactam/hexamethylene diammonium adipate copolymer (nylon 6/66), ethylene ammonium adipate/hexamethylene diammonium adipate/hexamethylene diammonium sebacate copolymer (nylon 6/66/610), polymers of meta-xylylenediamine and adipic acid (MXD-6), hexamethylene isophthalamide/terephthalamide copolymer (amorphous nylon), and so forth may be cited as examples. Furthermore, an adhesion improvement layer may be provided at the surface of a film comprising any of the examples of plastics cited above. As material for the adhesion improvement layer, acrylic, a water-soluble or water-dispersible polyester, a hydrophobic polyester in which acrylic is graft copolymerized, and so forth may be cited as examples.

Using plastic of any of the types described above by way of example as raw material, this may be used as desired as film formed so as to be unstretched, uniaxially stretched, or biaxially stretched, or as a coating in which this is dispersed in solvent or the like. In a case of forming a film, the film is preferably uniaxially stretched or biaxially stretched, more preferably biaxially stretched for achievement of mechanical strength. In this case, the printing layer and the substrate layer may be laminated with an adhesive layer, which will be described later, interposed therebetween or the substrate layer may be laminated during the extrusion process when the printing layer is formed.

The substrate layer preferably contains a lubricant in order to improve the lubricity, and the contained concentration is preferably 100 ppm or more and 2000 ppm or less. It is not preferred that the lubricant concentration is less than 100 ppm since the lubricity deteriorates, and thus not only position shift and the like occur when a laminated body is fabricated (bonded) but also the handling properties decreases when the laminated body is formed. It is not preferred that the lubricant concentration exceeds 2000 ppm since the transparency of the substrate layer decreases. The lubricant concentration is more preferably 200 ppm or more and 1900 ppm or less, still more preferably 300 ppm or more and 1800 ppm or less.

To cause the printing properties and/or lubricity of surface(s) thereof to be made satisfactory, it is possible for the substrate layer to be made to comprise layer(s) that have undergone corona treatment, coating treatment, flame treatment, and/or the like, it being possible for same to be comprised thereby as desired without departing from the requirements of the present invention.

1.6. Other Layers

The packaging of the present invention may have layers other than the laser printing layer and sealing layer described above. Taking the configuration described in the “1.1. Layer Configuration and Thickness” as an example, the substrate layer, gas barrier layer (transparent, opaque), and print layer will be described below.

1.6.1. Gas Barrier Layer

The gas barrier layer that can be arbitrarily laminated in the laminated body of the present invention is preferably composed of an inorganic thin film containing a metal or metal oxide as a main component. In addition to the gas barrier composed of the inorganic thin film, the laminated body may further include an anchor coat layer provided under the inorganic thin film layer (between the plastic film and the inorganic thin film) and an overcoat layer provided above the inorganic thin film layer. By providing these layers, improvement in close contact properties to the gas barrier layer, improvement in gas barrier properties, and the like can be expected.

The type of raw material for the gas barrier layer is not particularly limited, and conventionally known materials can be used, the raw material can be appropriately selected according to the purpose in order to satisfy the desired gas barrier properties and the like. Examples of the type of raw material for the gas barrier layer include metals such as silicon, aluminum, tin, zinc, iron, and manganese, and inorganic compounds containing one or more of these metals, and examples of the inorganic compounds include oxides, nitrides, carbides, and fluorides. These inorganic substances or inorganic compounds may be used singly or in combination.

In a case where the gas barrier layer is transparent, silicon oxide (SiOx) and aluminum oxide (AlOx) can be used singly (simple substances) or in combination (binary substances). In a case where the component of the inorganic compound consists of a binary substance of silicon oxide and aluminum oxide, the content of aluminum oxide is preferably 20% by mass or more and 80% by mass or less, more preferably 25% by mass or more and 70% by mass or less. It is not preferred that the content of aluminum oxide is 20% by mass or less since the density of the gas barrier layer may decrease and the gas barrier properties may decrease. It is not preferred that the content of aluminum oxide is 80% by mass or more since the flexibility of the gas barrier layer may decrease, cracking is likely to occur, and as a result, the gas barrier properties may decrease.

The oxygen/metal element ratio in the metal oxide used for the gas barrier layer is preferably 1.3 or more and less than 1.8 since there is little variation in gas barrier properties and excellent gas barrier properties can always be acquired. The oxygen/metal element ratio can be determined by measuring the amounts of the respective elements of oxygen and metal by X-ray photoelectron spectroscopy (XPS) and calculating the oxygen/metal element ratio.

The thickness of the gas barrier layer that can be preferably used in the laminated body of the present invention is preferably 2 nm or more and 100 nm or less in a case where a metal or metal oxide is vapor-deposited and used as a gas barrier layer. It is not preferred that the thickness of this layer is less than 2 nm since the gas barrier properties are likely to decrease. It is not preferred that the thickness of this layer exceeds 100 nm since there is no corresponding effect of improving gas barrier properties and the manufacturing cost increases. The thickness of the inorganic thin film layer is more preferably 5 nm or more and 97 nm or less, still more preferably 8 nm or more and 94 nm or less.

In a case where a metal foil is used as the gas barrier layer, the thickness of the metal foil is preferably 3 μm or more and 100 μm or less. It is not preferred that the thickness of this layer is less than 3 μm since the gas barrier properties are likely to decrease. It is not preferred that the thickness of this layer exceeds 100 nm since there is no corresponding effect of improving gas barrier properties and the manufacturing cost increases. The thickness of the inorganic thin film layer (metal foil) is more preferably 5 μm or more and 97 μm or less, still more preferably 8 μm or more and 94 μm or less.

In a case where the gas barrier layer is opaque, the gas barrier layer can be formed by pasting aluminum foil or vapor-depositing aluminum. The thickness of the aluminum foil is preferably 1 μm or more and 100 μm or less.

The gas barrier laminated body thus provided preferably has a water vapor transmission rate of 0.05 [g/(m²·d)] or more and 4 [g/(m²·d)] or less in an environment having a temperature of 40° C. and a relative humidity of 90% RH. It is not preferred that the water vapor transmission rate exceeds 4 [g/(m²·d)] since the shelf life of the contents is shortened in a case where the laminated body is used as packaging containing the contents. It is preferred that the water vapor transmission rate is less than 0.05 [g/(m²·d)] since the gas barrier properties are enhanced and the shelf life of the contents is extended, but the lower limit of water vapor transmission rate is 0.05 [g/(m²·d)] in the current technical level. When the lower limit of water vapor transmission rate is 0.05 [g/(m²·d)], it can be said that it is practically sufficient. The upper limit of water vapor transmission rate is preferably 3.8 [g/(m²·d)], more preferably 3.6 [g/(m²·d)].

The gas barrier laminated body preferably has an oxygen transmission rate of 0.05 [cc/(m²·d·atm)] or more and 4 [cc/(m²·d·atm)] or less in an environment having a temperature of 23° C. and a relative humidity of 65% RH. It is not preferred that the oxygen transmission rate exceeds 4 [cc/(m²·d·atm)] since the shelf life of the contents is shortened. It is preferred that the oxygen transmission rate is less than 0.05 [cc/(m²·d·atm)] since the gas barrier properties are enhanced and the shelf life of the contents is extended, but the lower limit of oxygen transmission rate is 0.05 [cc/(m²·d·atm)] in the current technical level. When the lower limit of oxygen transmission rate is 0.05 [cc/(m²·d·atm)], it can be said that it is practically sufficient. The upper limit of oxygen transmission rate is preferably 3.8 [cc/(m²·d·atm)], more preferably 3.6 [cc/(m·d·atm)].

In the gas barrier laminated body obtained using the laminated body of the present invention (in this section, these are collectively referred to as “laminated body”), an overcoat layer may be provided on the gas barrier layer for the purpose of improving scratch resistance and further improving gas barrier properties, and the like.

The type of overcoat layer is not particularly limited, but conventionally known materials, such as compositions containing urethane-based resins and silane coupling agents, compounds containing organosilicon and hydrolysates thereof, water-soluble polymers having hydroxyl or carboxyl groups, can be used, and the materials can be appropriately selected according to the purpose in order to satisfy the desired gas barrier properties and the like.

For the purpose of imparting antistatic properties, ultraviolet absorbency, coloring, thermal stability, lubricity and the like, one or more of various additives may be added to the overcoat layer as long as the object of the present invention is not impaired, and the types and amounts of various additives can be appropriately selected according to the desired purpose.

1.6.2. Print Layer

In addition to printing by laser irradiation, characters or patterns may be provided for the purpose of improving design. As materials for forming these characters and patterns, known materials such as ink for gravure printing and ink for flexographic printing can be used. Regarding the number of print layer(s), there may be one such layer or there may be a plurality of such layers. So as to be able to improve design properties by printing a plurality of colors, it is preferred that there be print layer(s) that comprise a plurality of layers. There will be no objection regardless of whether print layer(s) are disposed at surfacemost layer(s) or at intermediate layer(s).

2. Properties of Packaging

2.1. Difference in Color L* Value (Non-Printed Portion—Printed Portion)

In the packaging of the present invention, it is required that the absolute value of the difference in color L* value between the printed portion and the non-printed portion (hereinafter sometimes referred to simply as “difference in L* value”) be 1.0 or more and 10.0 or less. When this difference is less than 1.0, the color tones of the printed portion and non-printed portion become close to each other, and this makes it difficult to visually recognize the printing. It is not preferred that the difference in L* value exceeds 10.0 since the printing is likely to be visually recognized, but it is necessary to increase the laser irradiation power accordingly, this may cause great damage to the packaging, and problems such as perforation of the packaging are likely to occur. It is more preferred that the difference in L* value be 1.5 or more and 9.5 or less, and still more preferred that this be 2.0 or more and 9.0 or less.

2.2. Adhesive Strength Between Sealing Layers

The packaging of the present invention is required to have a peel strength (hereinafter, described as sealing strength in some cases) of 2 N/15 mm or more and 80 N/15 mm or less at the portion where the sealing layers are pasted to each other. It is not preferred that the sealing strength is less than 2 N/15 mm since the sealed portion is easily peeled off. The sealing strength is more preferably 3 N/15 mm or more, still more preferably 4 N/15 mm or more. It is more preferable as the sealing strength is greater since the sealability of the packaging is enhanced, but the upper limit that can be acquired at present is about 80 N/15 mm. When the sealing strength is 40 N/15 mm, it can be said that it is sufficiently preferable for practical use.

2.3. Lamination Strength

In the packaging body of the present invention, the lamination strength between the laser printing layer and the layer adjacent to one side thereof is required to be 2 N/15 mm or more and 10 N/15 mm or less. It is not preferred that the lamination strength is less than 2 N/15 mm since not only delamination is likely to occur but also the sealing strength is likely to be less than 2 N/15 mm. It is preferred that the lamination strength exceeds 10 N/15 mm from the perspective of performance of the packaging, but the upper limit that can be acquired at present is about 10 N/15 mm. When the lamination strength is about 4 N/15 mm, it can be said that it is sufficiently preferable for practical use. In a case where there are two or more lamination layers among the configurations exemplified in “1.1. Layer Configuration and Thickness”, the difference in lamination strength between the respective lamination layers (the largest difference in lamination strength in a case where there are three or more lamination layers) is preferably 1.5 N/15 mm or less. It is not preferred that the difference in lamination strength between the respective lamination layers exceeds 1.5 N/15 mm since delamination is likely to occur in the lamination layer with the lowest lamination strength. It is considered that this is because when the lamination layer with the lowest lamination strength is partially peeled off (notched), stress concentrates there and delamination is likely to occur. By setting the difference in lamination strength between the respective lamination layers to 1.5 N/15 mm or less, it is considered that stress concentration is likely to be avoided and delamination is likely to be easily prevented even if notching occurs in a certain lamination layer.

The difference in lamination strength is more preferably 1 N/15 mm or less, still more preferably 0.5 N/15 mm or less, particularly preferably 0 N/15 mm. It is preferred that the difference in lamination strength between the lamination layers is 0 N/15 mm since the lamination strengths between the respective lamination layers are all the same and delamination is less likely to occur.

2.4. Printing Size

With regard to the printing size formed on the packaging of the present invention by laser, it is preferred that either the height or the width be 0.2 mm or more and 100 mm or less. As it is said that the resolving power of the human eye is on the order of 0.2 mm, when the size of character falls below 0.2 mm, the difference in color L* value is likely to be less than 1.0, making recognition of printing difficult. On the other hand, when the printing size is above 100 mm, while this is preferred inasmuch as it facilitates recognition of printing, this is not preferred since when the printing size is too large it will cause the amount of information written on the packaging to be too small. It is more preferred that the printing size be 0.5 mm or more and 90 mm or less, and still more preferred that this be 1 mm or more and 80 mm or less.

2.5. Heat Shrinkage Rate

In the packaging of the present invention, it is preferred that the heat shrinkage rate is −5% or more and 5% or less in at least one arbitrary direction on the plane of the packaging when an arbitrary portion where the innermost layers are not sealed is cut and treated in hot air at 150° C. for 30 minutes. It is not preferred that the heat shrinkage rate exceeds 5% since the deformation is great and the original shape is not maintained when the packaging is placed in a high-temperature environment for hot water treatment such as boiling or retorting, warming using a microwave oven, and the like, and the design of the packaging is significantly impaired. It is not preferred that the heat shrinkage rate by warm water is less than −5% since this means that the packaging stretches and the packaging cannot maintain its original shape in the same way as when the heat shrinkage rate is high. It is more preferred that the heat shrinkage rate of packaging be −4% or more and 4% or less, and still more preferred that this be −3% or more and 3% or less.

2.6. Tensile Fracture Strength

In the packaging of the present invention, it is preferred that the tensile fracture strength is 40 MPa or more and 400 MPa when an arbitrary portion where the innermost layers are not sealed is cut and the tensile fracture strength is measured in at least one arbitrary direction on the plane of the packaging. When the tensile fracture strength is below 40 MPa, this is not preferred, since it will cause the packaging to fracture easily under external tension. It is more preferred that the lower limit of the range in values for tensile fracture strength be 50 MPa, and still more preferred that this be 60 MPa. On the other hand, while a tensile fracture strength that exceeds 400 MPa would be preferred in terms of mechanical strength, the level of the art of the present invention is such that the upper limit of the range in values therefor is 400 MPa. As a practical matter, even where tensile fracture strength is 300 MPa, this will be adequate.

3. Manufacturing Conditions

3.1. Plastic Film Layer (Laser Printing Layer, Sealing Layer, Other Layers)

The laser printing layer, sealing layer, and other layers that constitute the packaging of the present invention can be manufactured by the methods and conditions described below. In the following, the methods and conditions will be described mainly taking the laser printing layer as an example.

3.1.1. Mixing and Supply of Raw Materials

In manufacturing the laser printing layer included in the packaging of the present invention, it is necessary to add the laser printing pigments described in the “1.2.1. Types of Laser Printing Pigments, Amounts Thereof Added, and Methods for Adding Same”.

The laser printing pigment is a metal, and thus usually has a higher specific gravity than the resin constituting the film. Causing two or more types of raw materials having different specific gravities to be mixed and fed to an extruder in this fashion is likely to cause occurrence of variation (segregation) in the supply of raw materials. To prevent such variation, it is preferred that agitator(s) be installed at hopper(s) and plumbing immediately above extruder(s), that plumbing (inner piping) be inserted at interior(s) of hopper(s) immediately above extruder(s) filled with base resin and that laser printing pigment be supplied thereby, that tapered collars for lowering granular pressure of raw materials be installed at respective raw material hoppers, and/or that other such strategy or strategies be adopted to carry out melt extrusion.

3.1.2. Melt Extrusion (Lamination by Co-Extrusion)

A laser printing layer may be obtained by causing raw materials supplied in “3.1.1. Mixing and Supply of Raw Materials” to be melt-extruded by extruder(s) to form an unstretched film, and causing this to undergo the prescribed processes indicated below. A sealing layer and a substrate layer may be laminated together with the laser printing layer in the extrusion process, and each layer can be laminated at arbitrary timing. It is preferable to employ a co-extrusion method for lamination during melt extrusion. This is a method in which resins, which are raw materials for the respective layers, are each melt-extruded by separate extruders, and joined using a feed block or the like in the middle of the resin flow path. Extrusion lamination may be employed in which a resin to be the sealing layer is melt-extruded from a slot die and laminated in an arbitrary process from after extrusion of the laser printing layer to winding.

As method for melt extruding resin raw material, known methods may be employed, methods employing extruder(s) equipped with barrel(s) and screw(s) being preferred. It is preferred that a hopper dryer, paddle dryer, or other such dryer and/or vacuum dryer be used in advance to cause raw material (polyester, polyamide or the like) that might otherwise decompose due to the effect of moisture when molten to be dried until the moisture content thereof is 100 ppm or less, more preferably 90 ppm or less, and still more preferably 80 ppm or less. After the raw material has been dried in such fashion, the resin that has been melted by extruder(s) is quenched, as a result of which it is possible to obtain unstretched film. With respect to extrusion, this may be carried out by adopting the T die method, tubular method, and/or any other such known method as desired.

By thereafter quenching the film that is molten due to having been extruded, it is possible to obtain unstretched film. As method for quenching molten resin, a method on which the molten resin from the orifice fixture is cast onto a rotating drum where it is quenched and allowed to solidify to obtain a substantially unoriented resin sheet might be favorably adopted.

The film serving as laser printing layer may be formed in accordance with any of the following techniques: unstretched; uniaxially stretched (stretching in at least one of either the vertical (machine) direction or the horizontal (transverse) direction); biaxially stretched. However, in consideration of mechanical strength, uniaxial stretching is preferred, and biaxial stretching is more preferred. By forming a stretched film, it is possible to prevent decreases in in mechanical strength and elongation due to the use of a laser printing pigment. Similarly, the substrate layer is also preferably uniaxially stretched, more preferably biaxially stretched. However, the sealing layer is preferably unstretched for achievement of sealing strength.

While the description that follows is given with a focus on the sequential biaxial stretching method employing machine direction stretching—transverse direction stretching in which stretching is first carried out in the machine direction and stretching is subsequently carried out in the transverse direction, there is no objection to transverse direction stretching—machine direction stretching in which the order is reversed, as this will merely cause a change in the principal orientation direction. There would moreover be no objection to the simultaneous biaxial stretching method in which stretching in the machine direction and transverse direction are carried out simultaneously.

3.1.3. First (Machine Direction) Stretching

Stretching in the first direction (vertical or machine direction) may be carried out by causing the film to be fed into a machine direction stretching device in which a plurality of groups of rolls are arranged in continuous fashion. In carrying out machine direction stretching, it is preferred that preheating roll(s) be used to carry out preheating of the film. The preheating temperature is set so as to be between glass transition temperature Tg and melting point Tm+50° C., as determined based on the Tg of the plastic that makes up the film. When the preheating temperature is less than Tg, this is not preferred since stretching will be difficult at the time that stretching in the machine direction is carried out, and there will be a tendency for fracture to occur. It is not preferred the heating temperature is higher than Tm+50° C. since the film is likely to stick to the roll and the film is likely to be wound around the roll.

When film reaches between Tg and Tm+50° C., stretching in the machine direction is carried out. The stretching ratio in the machine direction should be 1× or more and 5× or less. As 1× would mean that there is no stretching in the machine direction, the stretching ratio in the machine direction should be 1× to obtain film which is uniaxially stretched in the transverse direction, and the stretching ratio in the machine direction should be 1.1× or more to obtain biaxially stretched film. Causing the machine direction stretching ratio to be 1.1× or more is preferred, since this will cause void(s) to be formed within the printing layer. While there is no objection to employment of any value as the upper limit of the range in values for the stretching ratio in the machine direction, as too great a stretching ratio in the machine direction will increase the tendency for fracture to occur during the stretching in the transverse direction that follows, it is preferred that this be 10× or less. It is more preferred that the stretching ratio in the machine direction be 1.2× or more and 9.8× or less, and still more preferred that this be 1.4× or more and 9.6× or less.

3.1.4. Second (Transverse Direction) Stretching

Following first (machine direction) stretching, it is preferred that stretching in the transverse direction be carried out at a stretching ratio of on the order of 2× to 13× at between Tg and Tm+50° C. while in a state such that the two ends in the transverse direction (the direction perpendicular to the machine direction) of the film are gripped by clips within a tenter. Before carrying out stretching in the transverse direction, it is preferred that preheating be carried out, in which case preheating should be carried out until the temperature at the display material or packaging surface reaches between Tg and Tm+50° C.

It is more preferred that the stretching ratio in the transverse direction be 2.2× or more and 12.8× or less, and still more preferred that this be 2.4× or more and 12.6× or less. Since the stretching rates are different for stretching in the machine direction versus stretching in the transverse direction (the stretching rate is higher for stretching in the machine direction), the preferred stretching ratio ranges are different. It is preferred that the area ratio which is the product of the machine direction stretching and transverse direction stretching ratios be 2.2× or more and 64×.

Following stretching in the transverse direction, it is preferred that the film be made to pass through an intermediate zone in which no procedure such as would cause it to be actively heated is performed. Relative to the zone in which stretching in the transverse direction is carried out at the tenter, since the temperature at the final heat treatment zone that follows is high, failure to establish an intermediate zone would cause heat (hot air itself and/or radiated heat) from the final heat treatment zone to flow into the operation at which stretching in the transverse direction is carried out. In this case, since the temperature in the zone in which stretching in the transverse direction is carried out would not be stable, there would be occurrence of variation in physical properties. It is therefore preferred that following stretching in the transverse direction the film be made to pass through an intermediate zone until a prescribed time has elapsed before final heat treatment is performed. It is important when in this intermediate zone, where rectangular strips are made to hang down from above while the film is kept from passing therethrough, that hot air from the final heat treatment zone and from the zone in which stretching in the transverse direction is carried out as well as any concomitant flow that would otherwise accompany movement of the film be blocked, so that those strips are made to hang down from above in almost perfectly vertical fashion. It will be sufficient if the time of passage through the intermediate zone is on the order of 1 second to 5 seconds. When the time is less than 1 second, length of time in the intermediate zone will be insufficient, and there will be inadequate heat blocking effect. On the other hand, while longer times in the intermediate zone are preferred, since too long a time therein would result in increased equipment size, on the order of 5 seconds will be sufficient.

3.1.5. Heat Treatment

Following passage through the intermediate zone, it is preferred at the heat treatment zone that heat treatment be carried out at between 100° C. and 280° C. Since heat treatment promotes crystallization of the film, not only will this make it possible to reduce any heat shrinkage that occurred during stretching operation(s), but this will also tend to increase tensile fracture strength. When heat treatment temperature is less than 100° C., this is not preferred since it would tend to increase the heat shrinkage of the film. On the other hand, when heat treatment temperature exceeds 280° C., this is not preferred since the film will tend to melt, and tensile fracture strength will tend to be reduced. It is more preferred that the heat treatment temperature be between 110° C. and 270° C., and still more preferred that this be between 120° C. and 260° C.

It is preferred that the time of passage through the heat treatment zone be 2 seconds or more and 20 seconds or less. When the time of passage therethrough is 2 seconds or less, heat treatment will be meaningless since the film will pass through the heat treatment zone without the surface temperature of the film having reached the temperature setpoint. Since the longer the time of passage therethrough the greater will be the effect of heat treatment, it is more preferred that this be 5 seconds or more. But since attempting to increase the length of time of passage therethrough would result in increased equipment size, as a practical matter it will be sufficient if this is 20 seconds or less.

During heat treatment, decreasing the distance between tenter clips (causing relaxation in the transverse direction) by some desired ratio will make it possible to reduce heat shrinkage in the transverse direction. For this reason, it is preferred during final heat treatment that the film be made to undergo relaxation in the transverse direction within the range 0% or more and 10% or less (a percent relaxation of 0% indicating that the film is not made to undergo relaxation). Whereas the higher the percent relaxation in the transverse direction the greater will be the reduction in shrinkage in the transverse direction, as the upper limit of the range in values for the percent relaxation (shrinkage of film in the transverse direction immediately following stretching in the transverse direction) is determined by the raw materials used, the conditions under which stretching in the transverse direction was carried out, and the heat treatment temperature, it will not be possible to cause the film to undergo relaxation to the point where this would be exceeded. At a laser printing layer making up a display material in accordance with the present invention, the upper limit of the range in values for the percent relaxation in the transverse direction is 10%. Furthermore, during heat treatment, it is also possible to decrease the distance between clips in the machine direction by some desired ratio (to cause relaxation in the machine direction).

3.1.6. Cooling

Following passage through the heat treatment zone, it is preferred at the cooling zone that a cooling airstream at 10° C. or more and 50° C. or less be used to carry out cooling of the film for a passage time therethrough of 2 seconds or more and 20 seconds or less.

By thereafter causing the film to be rolled up as portions cut from the two ends thereof are removed therefrom, a film roll is obtained.

3.2. Lamination

When the laminated body used in the packaging of the present invention is manufactured, in a case where the laser printing layer, the sealing layer and other layers (including a gas barrier layer, an anchor coat layer and an overcoat layer that are laminated on any layer, if necessary) are separately formed by the methods described in the “3.1. Film Manufacturing Conditions” and then laminated, the lamination method is not particularly limited, and adjacent layers can be laminated by conventionally known dry lamination or extrusion lamination using laminating agents such as those described in the “1.4. Laminating Agent”. In order to laminate the laser printing layer, the sealing layer and other layers in the present invention, there is a method in which a laminating agent is applied to one of the layers, the other layer is then bonded to the la coated surface, and drying is performed to volatilize the solvent. The drying conditions vary depending on the laminating agent, but the laminating agent is cured by, for example, being left to stand in an environment of 40° C. for one day or longer.

3.3. Gas Barrier Layer

The method for forming the gas barrier layer is not particularly limited, and known manufacturing methods can be employed as long as the object of the present invention is not impaired. Among known manufacturing methods, it is preferable to employ a vapor deposition method. Examples of the vapor deposition method include a vacuum vapor deposition method, a sputtering method, a PVD (physical vapor deposition) method such as ion blating, and a CVD (chemical vapor deposition) method. Among these, the vacuum vapor deposition method and the physical vapor deposition method are preferred, and the vacuum vapor deposition method is particularly preferred from the viewpoint of production speed and stability. As a heating mode in the vacuum deposition method, resistance heating, high-frequency induction heating, electron beam heating, or the like can be used. Oxygen, nitrogen, water vapor, or the like may be introduced as a reactive gas, or reactive vapor deposition using means such as ozone addition or ion assist may be used. The film forming conditions may be changed, such as applying a bias to the substrate, raising the temperature of the substrate, or cooling the substrate, as long as the object of the present invention is not impaired.

Here, a method for forming a gas barrier layer by a vacuum deposition method will be described. When a gas barrier layer is formed, the laminated body of the present invention is conveyed to a gas barrier layer manufacturing apparatus via a metal roll. As an example of the configuration of the gas barrier layer manufacturing apparatus, the apparatus includes an unwinding roll, a coating drum, a winding roll, an electron beam gun, a crucible, and a vacuum pump. The laminated body is set on the unwinding roll, passes through the coating drum, and is wound around the winding roll. The pressure in the pass line of the laminated body (inside the gas barrier layer manufacturing apparatus) is reduced by the vacuum pump, an inorganic material set in the crucible is vaporized by a beam emitted from the electron gun and deposited onto the laminated body that passes through the coating drum. During the deposition of inorganic material, the laminated body is subjected to heat and tension between the unwinding roll and the winding roll. It is not preferred that the temperature applied to the laminated body is too high since the laminated body undergoes not only great heat shrinkage but also softening and the elongation deformation due to tension is likely to occur. Furthermore, the temperature drop (cooling) of the laminated body after the vapor deposition process is large, the amount of shrinkage after expansion (different from heat shrinkage) is large, the gas barrier layer cracks, and the desired gas barrier properties are less likely to be exerted. It is more preferable as the temperature applied to the laminated body is lower since the deformation of laminated body is suppressed, but the amount of inorganic material vaporized decreases, the thickness of the gas barrier layer thus decreases, and there is a concern that the desired gas barrier properties are not achieved. The temperature applied to the laminated body is preferably 100° C. or more and 180° C. or less, more preferably 110° C. or more and 170° C. or less, still more preferably 120° C. or more and 160° C. or less.

In a case where an aluminum foil is pasted as an opaque gas barrier layer, the aluminum foil can be pasted by the method mentioned in the “1.4. Adhesive Layer”.

3.4. Overcoat Layer

When an overcoat layer is formed, the laminated body is conveyed to the coating equipment via a metal roll. Examples of equipment configuration include an unwinding roll, a coating process, a drying process, and a winding process. At the time of overcoating, the laminated body set on the unwinding roll is subjected to the coating process and the drying process via the metal roll and finally led to the winding roll. The coating method is not particularly limited, and conventionally known methods, such as a gravure coating method, a reverse coating method, a dipping method, a low coating method, an air knife coating method, a comma coating method, a screen printing method, a spray coating method, a gravure offset method, a die coating method, and a bar coating method, can be employed, and the coating method can be appropriately selected according to the desired purpose. Among these, a gravure coating method, a reverse coating method, and a bar coating method are preferred from the viewpoint of productivity. As the drying method, one heating method or a combination of two or more heating methods, such as hot air drying, hot roll drying, high frequency irradiation, infrared irradiation, and UV irradiation, can be used.

In the drying process, the laminated body is heated and also subjected to tension between the metal rolls. It is not preferred that the temperature at which the laminated body is heated in the drying process is too high since the laminated body undergoes not only great heat shrinkage but also softening, the elongation deformation due to tension is likely to occur, and the gas barrier layer of the laminated body is likely to crack. Furthermore, the temperature drop (cooling) of the laminated body after the drying process is large, accordingly the amount of shrinkage after expansion (different from heat shrinkage) is large, the gas barrier layer and the overcoat layer crack, and the desired gas barrier properties are less likely to be achieved. It is more preferable as the temperature at which the laminated body is heated is lower since the deformation of laminated body is suppressed, but the solvent of the coating liquid is less likely to be dried, and there is thus a concern that the desired gas barrier properties are not achieved. The temperature at which the laminated body is heated is preferably 60° C. or more and 200° C. or less, more preferably 80° C. or more and 180° C. or less, still more preferably 100° C. or more and 160° C. or less.

3.5. Packaging

As the shape and bag-making method of the packaging of the present invention, conventionally known technologies can be arbitrarily employed. Examples of the shape of the packaging include bags such as a vertical pillow, a horizontal pillow, a three side seal bag, a four side seal bag, a gusset bag, a stick package, and a standing pouch. A laminated body can be fabricated using the respective layers and laminating agent described in the “1. Configuration of Packaging”, and then the innermost layers of the laminated body can be sealed to make a bag. As a sealing method, heat sealing such as heat sealing and impulse sealing or an adhesive such as hot melt may be used, and the sealing method can be arbitrarily selected according to the adhesion performance of the sealing layers as long as the sealing strength between the innermost layers is within the prescribed range.

3.6. Laser Printing Conditions

As types (wavelengths) of lasers that may be used to carry out laser printing on the packaging in accordance with the present invention, CO₂lasers (10600 nm), YAG lasers (1064 nm), YVO₄lasers (1064 nm), fiber lasers (1064 nm and 1090 nm), green lasers (532 nm), and UV lasers (355 nm) may be cited. Among these, while there is no particular limitation with respect to the type of laser employed at printing of the present invention, CO₂lasers being often used for ablation of plastic, as they are often used for a purpose that is different from printing which is the intention of the present invention, they are not preferred as a laser source. As laser source, YAG lasers, YVO₄lasers, fiber lasers, green lasers, and UV lasers are preferred, YAG lasers, fiber lasers, and UV lasers being more preferred. Commercially available devices may be used for laser printing, representative examples of which that may be cited including the LM-2550 (YAG laser) manufactured by Brother Industrial Printing, Ltd.; the MX-Z2000H-V1 (fiber laser) manufactured by Omron Corporation; the 8028 Trotec Speedy 100 flexx (fiber laser) manufactured by Trotec; the MD-X1000 (YVO₄laser) and the MD-U1000C (UV laser) manufactured by Keyence Corporation; and so forth.

Regarding laser printing conditions, while the specifications and conditions that may be established will differ for each device manufacturer and for each model, and will moreover differ depending on the film on which printing is to be carried out, for which reason it is impossible to speak to every situation, the following will apply where the MD-U1000C (UV laser; wavelength 355 nm) manufactured by Keyence Corporation is employed by way of example.

It is preferred that laser power be such that output is 20% or more and 80% or less of the maximum 13 W specified for the device. When output is less than 20%, this is not preferred, since printing density will be reduced, and visual perceivability will be reduced. When output is 80% or more, this is not preferred, since this will cause formation of holes in the display body. It is more preferred that output be 25% or more and 75% or less, and still more preferred that this be 30% or more and 70% or less. It is preferred that pulse frequency be 10 kHz or more and 100 kHz or less. When frequency falls below 10 kHz, this is not preferred, since the laser energy per irradiation will be high, and there will be a tendency for the fractional decrease in thickness at the printed portion to rise above 80 vol %. Conversely, when frequency rises above 100 kHz, although this will facilitate causing the fractional decrease in thickness at the printed portion to be 80 vol % or more, there are situations in which this will make it difficult to achieve a difference in color L* value at the printed portion that is 1 or more. It is more preferred that this be 15 kHz or more and 95 kHz or less, and still more preferred that this be 20 kHz or more and 90 kHz or less. It is preferred that scan speed be 10 mm/sec or more and 3000 mm/sec or less. When scan speed falls below 10 mm/sec, this is not preferred since the fact that printing speed will be extremely low will cause the display body production rate to be reduced. On the other hand, when scan speed rises above 3000 mm/sec, this is not preferred since printing density will be reduced and it will be difficult to achieve a difference in color L* value that is 1 or more. It is more preferred that scan speed be 100 mm/sec or more and 2900 mm/or less, and still more preferred that this be 200 mm/sec or more and 2800 mm/or less.

WORKING EXAMPLES

Next, although the present invention is described below in more specific terms by way of working examples and comparative examples, the present invention is not to be limited in any way by the modes employed in such working examples, it being possible for changes to be made as appropriate without departing from the gist of the present invention.

As Polyolefin A, FS2011DG3 manufactured by Sumitomo Chemical Co., Ltd., was used.

As Polyolefin B, FS7053G3 manufactured by Sumitomo Chemical Co., Ltd., was used.

60% by mass of CaCO₃was kneaded into Polyolefin A to obtain Polyolefin C.

60% by mass of TiO₂was kneaded into Polyolefin A to obtain Polyolefin D.

[Polyester A]

As Polyester A, RE553 manufactured by Toyobo Co., Ltd., was used.

[Polyester B]

As Polyester B, 50% by mass of TiO₂was kneaded into Polyester A to obtain Polyester B.

[Polyester C]

As Polyester C, Polyester A and “Tomatec Color 42-920A (Primary Constituent Bi₂O₃)” laser pigment (manufactured by Tokan Material Technology Co., Ltd.) were mixed (dry blended) at a mass ratio of 95:5, and this was fed into a screw-type extruder, where it was heated at 275° C. and melt blended. This molten resin was expelled with cylindrical shape in continuous fashion from a strand die, this being cut at a strand cutter to obtain chip-like Polyester C (masterbatch).

[Polyester D]

As Polyester D, RE555 (masterbatch into which 7000 ppm of SiO₂was kneaded) manufactured by Toyobo Co., Ltd., was used.

Respective polyolefin raw material and polyester raw material compositions are shown in Table 1.

TABLE 1

Name of raw
Laser printing pigment

material
Resin type
Type
Amount added

Polyolefin A
Polypropylene
Absence
—

Polyolefin B
Propylene-ethylene copolymer
Absence
—

Polyolefin C
Polypropylene
CaCO₃
60
wt %

Polyolefin D
Polypropylene
TiO₂
60
wt %

Polyolefin E
Polymethylpentene 70 wt %/
Absence
—

Polystyrene 30 wt %

Polyester A
polyethylene terephthalate
Absence
—

Polyester B
polyethylene terephthalate
TiO₂
50
wt %

Polyester C
polyethylene terephthalate
Bi₂O₃
5
wt %

Polyester D
polyethylene terephthalate
SiO₂
7000
ppm

Polyolefin A, Polyolefin C, and Polyolefin D were mixed at a mass ratio of 40:50:10 as raw material for Layer A; Polyolefin A, Polyolefin B, and Polyolefin C were mixed at a Mass ratio of 10:70:20 as raw material for Layer B.

The raw materials mixed for Layer A and Layer B were respectively fed into different screw-type extruders, and were melted and extruded from a T die at a shear rate of 1000 sec⁻¹. A feedblock was used partway along the flow paths of the respective molten resins so as to cause them to be joined, and this was expelled from a T die and taken up at a draft ratio of 1.2 as it was cooled on a chill roll, the surface temperature of which was set to 30° C., to obtain unstretched laminated film. Molten resin flow paths were established so as to cause the laminated film to be such that the central layer thereof was Layer A, and the two surfacemost layers thereof were Layer B (i.e., a B/A/B constitution in which there were three layers of two types), the amounts expelled therefrom being adjusted so as to cause the thickness ratio of Layer A and Layer B to be 90/10 (B/A/B=5/90/5).

The cooled and solidified unstretched laminated film which was obtained was guided to a machine direction stretching device in which a plurality of groups of rolls were arranged in continuous fashion, and this was made to undergo preheating on preheating rolls until the film temperature reached 125° C., following which this was stretched by a factor of 4×.

Following machine direction stretching, the film was guided to a transverse direction stretching device (tenter), where it was made to undergo preheating for 8 seconds until the surface temperature thereof reached 160° C., following which it was stretched by a factor of 9.8× in the transverse direction (horizontal direction). Following transverse direction stretching, the film was guided while still in that state to an intermediate zone, being made to pass therethrough in 1.0 second. While in the intermediate zone of the tenter, where rectangular strips were made to hang down from above while the film was kept from passing therethrough, hot air from the heat treatment zone and hot air from the zone in which stretching in the transverse direction was carried out was blocked, so that those strips were made to hang down from above in almost perfectly vertical fashion.

Thereafter, following passage through the intermediate zone, the film was guided to the heat treatment zone, where heat treatment was carried out for 9 seconds at 165° C. At this time, at the same time that heat treatment was being carried out, the distance between clips in the transverse direction of the film was reduced, causing this to undergo 3% relaxation treatment in the transverse direction. Following passage through the final heat treatment zone, the film was cooled for 5 seconds in a cooling airstream at 30° C. Portions were cut and removed from the two edges thereof and this was rolled up into a roll 400 mm in width to continuously manufacture a prescribed length of biaxially stretched film of thickness 70 μm. The properties of the film that was obtained were evaluated in accordance with the foregoing methods. The manufacturing conditions are shown in Table 2.

[Films 2-4]

In similar fashion as at Film 1, the various conditions were altered to continuously form films at Films 2 through 4. The manufacturing conditions for the respective films are shown in Table 2.

[Films 5-8]

PYLEN Film-CT (registered trademark) P1128-30 μm manufactured by Toyobo Co., Ltd., a unstretched polypropylene film was used as Film 5, LIX Film (registered trademark) L4102-30 μm manufactured by Toyobo Co., Ltd., an unstretched linear low-density polyethylene film, was used as Film 6, ESTER Film (registered trademark) E5102-12 μm manufactured by Toyobo Co., Ltd., a biaxially stretched polyethylene terephthalate film was used as Film 7, and HARDEN Film (registered trademark) N1102-15 μm manufactured by Toyobo Co., Ltd., a biaxially stretched polyamide film was used as Film 8. Names of the respective films are shown in Table 2.

TABLE 2

Film 1
Film 2
Film 3
Film 4
Film 5
Film 6
Film 7
Film 8

Raw material
Polyolefin A
40
55
0
0
P1128
L4102
E5102
N1102

composition of
Polyolefin B
0
0
0
0

layer A
Polyolefin C
50
20
0
0

[mass %]
Polyolefin D
10
25
0
0

Polyolefin E
0
0
7
0

Polyester A
0
0
88
90

Polyester B
0
0
5
0

Polyester C
0
0
0
3

Polyester D
0
0
0
7

Raw material
Polyolefin A
10
30
0
—

composition of
Polyolefin B
70
70
0
—

layer B
Polyolefin C
20
0
0
—

[mass %]
Polyolefin D
0
0
0
—

Polyolefin E
0
0
0
—

Polyester A
0
0
60
—

Polyester B
0
0
30
—

Polyester C
0
0
0
—

Polyester D
0
0
10
—

Laser pigment of
Type
TiO₂/CaCO₃
TiO₂/CaCO₃
TiO₂
Bi₂O₃

layer A
Amount added [wt %]
6.0/30
15/12
2.5
0.15

Laser pigment of
Type
CaCO₃
Absence
TiO₂
—

layer B
Amount added [wt %]
12
—
15
—

Resin content in laser printing layer [wt %]
85.6
73
91.25
99.85

Layer configuration
B/A/B
B/A/B
B/A/B
A

Thickness ratio among respective layers [vol %]
5/90/5
20/60/20
25/50/25
100

Stretching in machine
Temperature for
125
120
90
90

direction
stretching [° C.]

(machine direction
Stretching ratio
4.0
4.7
3.1
3.5

stretching)

Stretching in transverse
Temperature for
160
145
125
105

direction
stretching [° C.]

(transverse direction
Stretching ratio
9.8
10.1
4.2
3.8

stretching)

Heat treatment
Temperature [° C.]
165
160
230
230

Relaxation rate
3
8
6
3

(transverse direction) [%]

Film thickness [μm]
70
35
100
50
30
30
12
15

Working Example 1

Film 5 was bonded on Film 1 by dry lamination using a urethane-based two-pack curing adhesive (“TAKELAC (registered trademark) A525S” and “TAKENATE (registered trademark) A50” manufactured by Mitsui Chemicals, Inc. were blended at a weight ratio of 13.5:1), and aging was performed at 40° C. for 4 days to obtain a laminated body. At this time, the thickness of the adhesive layer was 3 μm.

This laminated body was cut into a size of 15 cm square, two sheets were superimposed so that Film 5 serving as the sealant was on the inner side, and three sides of the laminated body were heat-sealed to fabricate a bag having an inner dimension of 13 cm. The heat sealing conditions at this time were set to a temperature of 140° C., a pressure of 0.2 MPa, a time of 1 second, and a sealing width of 1.0 cm.

“12345ABCDE” was printed in the center of the film of the obtained bag at a pulse frequency of 40 kHz, a scanning speed of 2000 mm/min, and an output of 30% using a UV laser with a wavelength of 355 nm (Laser Marker MD-U1000C manufactured by Keyence Corporation). The size per character was approximately 5 mm in height× approximately 3 mm in width.

The layer configuration and physical property evaluation results for the obtained packaging are shown in Table 3.

Working Example 2

An aluminum oxide (Al₂O₃) thin film was formed as a gas barrier layer on one side of Film 7 using aluminum as a vapor deposition source by a vacuum deposition method while oxygen gas was introduced using a vacuum vapor deposition machine. The thickness of the gas barrier layer was 10 nm. The gas barrier layer side of Film 7 and Film 1 were bonded together in the same manner as in Example 1. Film 6 was further bonded on the Film 1 side of the bonded films in the same manner as the above to fabricate a laminated body.

Three sides of this laminated body were heat-sealed in the same manner as in Example 1 to fabricate a bag, and “12345ABCDE” was printed in the center of the film at a pulse frequency of 30 kHz, a scanning speed of 1500 mm/min, and an output of 80% using a fiber laser with a wavelength of 1064 nm (Laser Marker 8028 Trotec Speedy 100 flexx manufactured by Trotec) to fabricate a display body. The size per character was approximately 8 mm in height× approximately 5 mm in width.

The layer configuration and physical property evaluation results for the obtained packaging are shown in Table 3.

Working Examples 3-6; Comparative Examples 1 and 2

In similar fashion as at Working Example 1 and 2, the type of film used and laser source/irradiation conditions were variously altered to fabricate the display bodies of Working Examples 3 through 6 and Comparative Examples 1 and 2. MD-U1000C Laser Marker manufactured by Keyence Corporation was employed in all cases where a UV laser was used, and 8028 Trotec Speedy 100 flexx Laser Marker manufactured by Trotec was employed in all cases where a fiber laser was used. In Comparative Example 2, only the laser printing layer (Film 1) was used as a single body, and heat sealing was not performed. Therefore, one film was used for laser printing.

The layer configuration and physical property evaluation results for the obtained packaging are shown in Table 3.

Comparative Example 3

A laser printing layer was formed on one surface of Film 8 by coating a white ink layer with a gravure roll. The white ink layer was fabricated by mixing methyl ethyl ketone, isopropyl alcohol, polyurethane, and titanium oxide at a ratio of 11%:3%:38%:48% by mass. The thickness of the laser printing layer was 3 μm.

A laser printing layer (white ink layer) formed on Film 8 and Film 5 were bonded together in the same manner as in Example 1, and three sides were heat-sealed to obtain packaging. This packaging was irradiated with laser in the same manner as in Example 1 for printing.

The layer configuration and physical property evaluation results for the obtained packaging are shown in Table 3.

The evaluation method of the laminated body is as follows. For samples of the non-printed portion, the samples used were cut out from portions that were 1 mm or more away from any printed portion or sealed portion.

[Thickness]

The thickness was measured at five points using a micrometer (Millitron 1254D manufactured by Feinpruf GmbH), and the average value thereof was determined.

[Color L* Value (Printed Portion and Non-Printed Portion)]

A spectroscopic color difference meter (ZE-6000; manufactured by Nippon Denshoku Industries Co., Ltd.) was used in reflection mode to respectively measure the color L* values at the printed portion and the non-printed portion of a single film sample. The specific method used for measurement of the printed portion was as follows.

From the characters “12345ABCDE” printed as, a square sample which was 3 cm on a side was cut so as to contain the entirety of the “B” (it being considered acceptable at this time if character(s) other than the “B” also happened to be contained therein), and this was measured.

Furthermore, the light source for measurement at the color difference meter employed a 6φ stage (the aperture on which light for measurement fell being approximately 1 cm in diameter) and a 6p eyepiece, the aperture of the stage being arranged so as to contain the character “B” therewithin. In a case where printing was not completely contained within (i.e., protruded from) stage aperture, it was considered acceptable to change stage as necessary (e.g., 109, 309, etc.). Even where printing protruded therefrom, so long as a portion of printing was contained within stage aperture and light for measurement fell thereon, this was considered to be acceptable.

Furthermore, for the non-printed portion, a square sample which was 3 cm on a side was cut from the portion at which printing had not been carried out, and color L* values were measured using 69 components at the stage and eyepiece of the color difference meter. It was considered acceptable to change the stage and/or eyepiece of the color difference meter to 109, 309, or the like as necessary, in which case it was considered acceptable to employ a sample size of arbitrary size so long as it was such as to cause the aperture of the stage to be covered (i.e., so long as it did not allow light for measurement to leak past it).

[Adhesive Strength between Sealing Layers]

Measurement was performed in accordance with JIS Z1707. The adhesion sample was cut out so that the width direction (direction taken by 1 cm in heat sealing of the packaging) of the sealed portion was taken as the tensile direction, the length of the two laminated bodies pasted was 60 mm or more, and the direction (sample width during tensile test) perpendicular to the tensile direction was 15 mm. The sealing strength of this sample was measured at a distance between chucks of 50 mm and a tensile speed of 200 mm/min using a universal tensile tester “Autograph AG-Xplus” (manufactured by Shimadzu Corporation). The peel strength is indicated by strength per 15 mm (N/15 mm). When the sample cannot be cut out with a length of 60 mm or more due to limitations on the size of the packaging, the length may be 60 mm or less (for example, 20 mm). In this case, the distance between chucks may be set to 50 mm or less (for example, the distance between chucks is 10 mm in a case where the sample length is 20 mm) as long as the chuck on one side is provided with at least a length of 5 mm or more for gripping the sample.

[Lamination Strength]

A sample having a width of 15 mm and a length of 200 mm was cut out from the portion, which was not laser-printed and not sealed, of the packaging and used as a test piece, and the lamination strength was measured at a temperature of 23° C. and a relative humidity of 65% using a universal tensile tester “Autograph AG-Xplus” (manufactured by Shimadzu Corporation). At the time of the lamination strength measurement, the tensile speed was set to 200 mm/min and the peel angle was set to 90 degrees.

[Printing Size]

Among the characters “12345ABCDE” printed as, a stainless steel straightedge ruler (TZ-RS15 manufactured by Kokuyo Co., Ltd.) was used to measure by visual inspection in increments of 0.5 mm the heights and widths of those at “345ABC”, the average thereof being taken to be the printing size. Where the printing size was less than 0.5 mm, an RH-2000 digital microscope manufactured by Hirox Co., Ltd., was separately used to measure the printing size. Software provided with RH-2000 digital microscope manufactured by Hirox Co., Ltd., was used for measurement of the printing size.

[Heat Shrinkage Rate]

The film was cut into a 10 cm×10 cm square, immersed in hot water at 98° C.±0.5° C. for 10 seconds without load to be shrunk, then immersed in water at 25° C.±0.5° C. for 10 seconds, and removed from the water. After that, the dimensions of the film in the machine and transverse directions were measured, and the shrinkage rate in each direction was determined according to the following Equation 1. The measurement was performed 2 times and the average value thereof was determined.

Shrinkage rate={(Length before shrinkage−Length after shrinkage)/Length before shrinkage}×100(%) Equation 1

[Tensile Fracture Strength]

Strip-like film samples which were 140 mm in the measurement direction and 20 mm in the direction (transverse direction of the film) perpendicular to the measurement direction were prepared in accordance with JIS K7113. An “Autograph AG-Xplus” universal tensile tester (manufactured by Shimadzu Corporation) was used, the two ends of the test piece being held such that a 20 mm length thereof was gripped by a chuck at either end (chuck separation 100 mm), tensile testing being carried out under conditions of 23° C. ambient temperature and 200 mm/min elongation rate, strength (stress) at the time of tensile fracture being taken to be the tensile fracture strength (MPa). The machine direction and the transverse direction were used as measurement directions.

[Total Luminous Transmittance (Non-Printed Portion)]

A hazemeter (300A; manufactured by Nippon Denshoku Industries Co., Ltd.) was used to measure the total luminous transmittance of the non-printed portion in accordance with JIS-K-7136. Measurements were carried out twice, and the average thereof was determined.

[Water Vapor Transmission Rate]

The water vapor transmission rate was measured in conformity with JIS K7126 B method. The water vapor transmission rate was measured in the direction in which the humidity-conditioning gas permeated from the heat sealing layer side of the laminated body to the inorganic thin film layer side in an atmosphere having a temperature of 40° C. and a humidity of 90% RH using a water vapor transmission rate measuring instrument (PERMATRAN-W3/33MG manufactured by AMETEK MOCON). Before measurement, the sample was left to stand for 4 hours in an environment having a humidity of 65% RH to condition the humidity.

[Oxygen Transmission Rate]

The oxygen transmission rate was measured in conformity with JIS K7126-2 method. The oxygen transmission rate was measured in the direction in which oxygen permeated from the heat sealing layer side of the laminated body to the inorganic thin film layer side in an atmosphere having a temperature of 23° C. and a humidity of 65% RH using an oxygen transmission rate measuring instrument (OX-TRAN 2/20 manufactured by AMETEK MOCOM). Before measurement, the sample was left to stand for 4 hours in an environment having a humidity of 65% RH to condition the humidity.

[Visual Evaluation of Printed Portion]

Visual perceptibility of the characters “12345ABCDE” that were printed on the laminated body was judged based on the following criteria.

GOOD: Characters were recognizable as a result of visual inspection

BAD: Characters were unrecognizable as a result of visual inspection

TABLE 3A

Working
Working
Working
Working
Working

Example 1
Example 2
Example 3
Example 4
Example 5

Layer configuration
Outer side
Substrate Layer
—
Film 7
—
Film 7
Film 8

Gas Barrier Layer
—
Al₂O₃
—
—
Al₂O₃/SiO2

Adhesive layer
—
Urethane-based
—
Urethane-based
Urethane-based

3 μm

3 μm
3 μm

Laser printing layer
Film 1
Film 1
Film 2
Film 3
Film 4

Adhesive layer
Urethane-based
Urethane-based
Urethane-based
Urethane-based
Urethane-based

3 μm
3 μm
3 μm
3 μm
3 μm

Inner side
Sealing Layer
Film 5
Film 6
Film 5
Film 5
Film 5

Total thickness [μm]
105
102
88
148
101

Heat sealing condition
Temperature [° C.]
140
120
140
120
140

Pressure [MPa]
0.2
0.2
0.2
0.2
0.2

time [sec]
1
2
2
2
1

Seal width [cm]
1
1
1
1
1

Length of one side of bag (inner dimension) [mm]
13
20
13
13
13

Laser irradiation condition
Laser source
UV
Fiber
UV
Fiber
Fiber

Pulse frequency [kHz]
40
30
40
45
50

Scanning speed [mm/min.]
2000
1500
2000
800
1500

Output [%]
30
80
30
30
30

Printing size
Height [mm]
5
8
1
7
5.5

Width [mm]
3
5
1
7
4.5

Color
Printed portion
94.8
95.3
89.7
88.5
83.9

L* value
Non-printed portion
97.1
96.4
97.5
95.3
92.4

Difference
2.3
1.1
7.8
6.8
8.5

Adhesive strength between sealing layers [N/15 mm]
52
44
39
58
51

Lamination Strength
Gas barrier layer or substrate
4.8
4.1
4.4
4.2
4.1

(to laser printing layer) [N/15 mm]
layer side

Sealing layer side
4.3
4.6
3.8
4.3
4.2

Difference between
0.5
0.5
0.6
0.1
0.1

lamination layers

Heat shrinkage rate [%]
Machine direction
1.6
1.3
0.9
0.4
0.4

Transverse direction
1.3
1.2
0.8
0.3
0.4

Tensile fracture strength [MPa]
Machine direction
63
220
62
250
201

Transverse direction
166
234
147
267
228

Gas barrier properties
Water vapor transmission
5
1.5
6
6
1.3

rate (g/m²· d)

Oxygen transmission
389
1.2
401
9
0.9

rate (co/m²· d · atm)

Visual evaluation of printed portion (visual perceivability)
Good
Good
Good
Good
Good

TABLE 3B

Working
Comparative
Comparative
Comparative

Example 6
Example 1
Example 2
Example 3

Layer configuration
Outer side
Substrate Layer
Film 8
Film 7
—
Film 8

Gas Barrier Layer
Al
—
—
—

Adhesive layer
Urethane-based
—
—
—

3 μm

Laser printing layer
Film 1
—
Film 1
White ink layer

3 μm

Adhesive layer
Urethane-based
Urethane-based
—
Urethane-based

3 μm
3 μm

3 μm

Inner side
Sealing Layer
Film 6
Film 5
—
Film 5

Total thickness [μm]
101
45
50
50

Heat sealing condition
Temperature [° C.]
140
140
140
140

Pressure [MPa]
0.2
0.2
0.2
0.2

time [sec]
1
1
2
1

Seal width [cm]
1
1
1
1

Length of one side of bag (inner dimension) [mm]
30
13
—
13

Laser irradiation condition
Laser source
Fiber
UV
UV
UV

Pulse frequency [kHz]
60
40
40
40

Scanning speed [mm/min.]
2000
2000
2000
2000

Output [%]
30
30
30
30

Printing size
Height [mm]
9
—
5
5

Width [mm]
10
—
3
3

Color
Printed portion
91.2
96.3
94.5
92.1

L* value
Non-printed portion
94.2
96.3
97.2
97.6

Difference
3
0
2.7
5.5

Adhesive strength between sealing layers [N/15 mm]
41
32
0
34

Lamination Strength
Gas barrier layer or substrate layer side
4.6
4.1
—
—

(to laser printing layer) [N/15 mm]
Sealing layer side
5.1
4.5
—
1.6

Difference between lamination layers
0.5
0.4
—
—

Heat shrinkage rate [%]
Machine direction
1.3
0.5
1.1
0.8

Transverse direction
1.1
0.4
0.9
0.8

Tensile fracture strength [MPa]
Machine direction
260
218
50
203

Transverse direction
278
234
163
234

Gas barrier properties
Water vapor transmission rate (g/m²· d)
0.5
38
8
44

Oxygen transmission rate (cc/m²· d · atm)
0.5
98
421
289

Visual evaluation of printed portion (visual perceivability)
Good
Bad
Good
Good

[Manufacturing Conditions and Evaluation Results of Film]

All of the packaging of Examples 1 to 6 were excellent in the physical properties shown in Table 3.

On the other hand, in Comparative Example 1, the packaging did not include a printing layer, thus printing by laser was not possible, and the packaging was not preferable as laser-printed packaging.

In Comparative Example 2, a sealing layer was not provided, and thus packaging could not be fabricated.

In Comparative Example 3, since the laser printing layer was a white ink layer, the lamination strength with the sealing layer was insufficient, and packaging with a concern of delamination was obtained.

INDUSTRIAL APPLICABILITY

The present invention is excellent in lamination strength and visual perceptibility of laser-printed portions without using ink containing a laser pigment. It is thus possible to provide highly productive, economical and well-designed packaging without complicating the design of the packaging.

LASER-PRINTED PACKAGING

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