Laser-printed packaging

Abstract

The present invention is a packaging body having at least one laser printing layer that can be printed upon by using laser irradiation, where a non-printed portion and a laser-printed portion that has been printed by using a laser are present on the laser printing layer, and at least a portion of the packaging body is fusion-sealed. The present invention also satisfies conditions (1) to (3) below. In addition, a packaging body that includes laser printing that does not peel and that is formed by means of fusion sealing is provided in a highly productive and economical manner. (1) The thickness of the laser printing layer is 5 to 200 μm, inclusive (2) The difference in color L＊ values between the laser-printed portion and the non-printed portion is 1.0 to 10, inclusive (3) The fusion sealing strength is 5 to 40 N / 15 mm, inclusive

Description

[Technical Field]

[0001] The present invention relates to a package having a laser-printed layer and formed by heat sealing. [Background technology]

[0002] Traditionally, packaging made of plastic film has been widely used for distributed goods such as food, pharmaceuticals, and industrial products. Packaging comes in various forms depending on the manufacturing method and intended use, and one such form is packaging formed by heat sealing (hereinafter sometimes referred to as heat-sealed bags) (for example, Patent Document 1). Heat sealing is a technique in which plastic films are overlapped and bonded together with a hot blade. Many types of packaging, including heat-sealed bags, not only protect the contents but also serve to display information such as the product name, manufacturing date, and raw materials (hereinafter sometimes referred to as "printing").

[0003] In recent years, laser-printed packaging materials have been disclosed, such as those described in Patent Document 2. These materials achieve laser printing functionality by applying (coating) an ink layer containing a color-developing element (pigment) that reacts to a laser onto a base film. However, when using heat sealing as a method for creating this packaging material, coating the heat-sealable pigment on the heat-sealed surface (inner surface of the heat-sealed bag) may reduce the heat-seal strength and lead to bag breakage. To avoid this, coating the laser-printable pigment on the opposite side of the heat-sealed surface (outer surface of the heat-sealed bag) results in the problem of the laser-printable pigment peeling off. These problems can be solved by laminating (laminating) a film onto the surface coated with the laser-printable pigment, but this increases the number of steps and creates a new problem of reduced productivity. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 6736976 [Patent Document 2] Patent No. 6268873 [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention aims to solve the problems of the prior art described above. Specifically, the objective of the present invention is to provide a package that has laser printing that does not peel off and is formed by heat-sealing, under high productivity and economic efficiency. [Means for solving the problem]

[0006] The present invention consists of the following configuration. 1. A package having at least one laser-printable layer that can be printed by laser irradiation, wherein the laser-printable layer has laser-printed portions and non-printed portions, and at least a part of the package is heat-sealed, and the package satisfies the following requirements (1) to (3). (1) The thickness of the laser printing layer is 5 μm or more and 200 μm or less. (2) The difference in color L* value between the laser-printed area and the non-printed area is between 1.0 and 10. (3) The heat-sealing strength is 5N / 15mm or more and 40N / 15mm or less. 2. The packaging according to 1, characterized in that the height or width of the printed area in the laser-printed portion is 0.2 mm or more and 100 mm or less. 3. The packaging according to 1. or 2., characterized in that the laser printing layer extends over the entire surface area of ​​the packaging. 4. The packaging according to any one of claims 1 to 3, characterized in that the laser printing layer contains one or more elements or compounds 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, characterized in that the resin constituting the laser printing layer is mainly polyester, polypropylene, or polyethylene. [Effects of the Invention]

[0007] The present invention makes it possible to provide packaging with laser printing that does not peel off and formed by heat sealing, under high productivity and cost-effectiveness. [Modes for carrying out the invention]

[0008] The packaging of the present invention will be described below. 1. Packaging composition 1.1. Layer structure, thickness The packaging of the present invention must have at least one film layer (laser-printable layer) that can be printed by laser irradiation. The laser-printable layer has laser-printed portions in at least a portion of it, as well as non-printed portions. In the present invention, it is preferable that the laser-printable layer covers the entire area of ​​the packaging (in the planar direction). Furthermore, in order to improve the design, the packaging of the present invention may also have a printed layer containing characters or designs other than those formed by laser printing. The necessary or preferred requirements for these layers will be described later.

[0009] In the packaging of the present invention, in order to satisfy the requirements for heat-seal strength, the laser-printed layer may be provided with heat-seal properties, or a layer having heat-seal properties may be provided separately from the laser-printed layer. The requirements for achieving heat-seal strength will be described later. Furthermore, the packaging of the present invention may optionally be further provided with an anchor coat layer laminated to the base layer or adhesive layer, or an overcoat layer laminated to the gas barrier layer. By providing these layers, the gas barrier properties and abrasion resistance of the packaging can be improved.

[0010] The thickness of the film layer constituting the package (hereinafter sometimes referred to as the thickness of the package) is not particularly limited, but is preferably 5 µm or more and 300 µm or less. If the thickness of the package is less than 5 µm, it is not preferable because not only the visibility of laser printing is lowered, but also the mechanical strength and the fusing seal strength may be lowered. On the other hand, if the thickness of the package exceeds 300 µm, it is not preferable because heat transfer in the thickness direction of the film is insufficient during fusing sealing, which easily causes defective fusing. The thickness of the package is more preferably 10 µm or more and 295 µm or less, and even more preferably 15 µm or more and 290 µm or less.

[0011] The thickness of the laser printing layer constituting the package of the present invention needs to be 5 µm or more and 200 µm or less. If the thickness is less than 5 µm, even if the concentration of the laser printing pigment described later is increased, the visibility of laser printing may be deteriorated. On the other hand, if the thickness of the printing layer exceeds 200 µm, the above-mentioned defective fusing is likely to occur, which is not preferable. The thickness of the laser printing layer is more preferably 10 µm or more and 195 µm or less, and even more preferably 15 µm or more and 190 µm or less.

[0012] Furthermore, all layers constituting the package of the present invention may be provided with layers subjected to corona treatment, coating treatment, flame treatment or the like in order to improve properties such as surface printability and slipperiness, and such layers may be arbitrarily provided within a range not departing from the requirements of the present invention.

[0013] 1.2. Laser printing layer 1.2.1. Type, addition amount and addition method of laser printing pigment To make the printing layer constituting the present invention laser printable, it is necessary to add a laser printing pigment that has a discoloration function upon laser irradiation. The plastic that makes up the packaging body usually does not react much to laser light, so it cannot be printed by laser irradiation. The laser printing pigment is excited by the energy of the laser light, and printing becomes possible as the surrounding plastic is carbonized. In addition to the carbonization of the plastic, some types of laser printing pigments themselves change to black. Printing on the printing layer becomes possible through the combined or individual effects of this carbonization and the discoloration of the laser printing pigment. From the viewpoint of print density, it is preferable to select a laser printing pigment that has both the carbonization of plastic and its own discoloration function.

[0014] Specific types of laser printing pigments include bismuth, gadolinium, neodymium, titanium, antimony, tin, aluminum, calcium, and barium, either as elements or oxides. Of these, titanium dioxide, calcium carbonate, bismuth trioxide, antimony trioxide, and barium sulfate are preferred, and titanium dioxide, calcium carbonate, and bismuth trioxide are more preferred. Furthermore, the particle size of the laser printing pigment is preferably 0.1 μm or more and 10 μm or less. If the particle size of the laser printing pigment is less than 0.1 μm, the color change during laser irradiation may not be sufficient. On the other hand, if the particle size of the laser printing pigment exceeds 10 μm, there is a concern that it may accelerate the clogging of the filter during the extrusion process when forming the film. The particle size of the laser printing pigment is more preferably 1 μm or more and 9 μm or less, and even more preferably 2 μm or more and 8 μm or less.

[0015] 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. If the added amount of the pigment is less than 0.05% by mass, the printing density obtained by laser irradiation becomes insufficient, which is not preferable. On the other hand, if the added amount of the pigment exceeds 50% by mass, the amount (volume) of carbonized plastic relatively decreases, which may also result in insufficient printing density. The added amount of the laser printing pigment is more preferably 0.1% by mass or more and 49% by mass or less, further preferably 0.15% by mass or more and 48% by mass or less, and particularly preferably 0.2% by mass or more and 47% by mass or less. In cases where the laser printing layer is formed of a plurality of layers, the total added amount of the laser printing pigment in the entire laser printing layer can be obtained by proportional distribution based on the thickness ratio of each layer and the added amount of the laser printing pigment in each layer.

[0016] As a method for blending the laser printing pigment, the pigment can be added at any stage of producing a resin that serves as a raw material for the laser printing layer or a film that serves as the laser printing layer. For example, in the step of producing the resin, examples include a method of blending a slurry of particles dispersed in a solvent and a plastic raw material using a vented kneading extruder, and a method of blending dried particles and a plastic resin using a kneading extruder (masterbatch formation). Among these, a method of using a masterbatch containing a laser printing pigment as a raw material for a film is preferable.

[0017] 1.2.2. Type of Plastic The type of plastic constituting the laser printing layer of the present invention is not particularly limited, and any plastic can be freely used without departing from the scope and spirit of the present invention. Examples of the type of plastic (resin) include polyester, polyolefin, polyamide, and the like. Examples of polyesters include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polytrimethylene terephthalate (PTT), polybutylene naphthalate (PBN), polylactic acid (PLA), polyethylene furanoate (PEF), and polybutylene succinate (PBS). In addition to the polyesters listed above, modified polyesters obtained by changing the monomers of the acid or diol portion may also be used. Examples of monomers for the acid portion include aromatic dicarboxylic acids such as isophthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and orthophthalic acid, as well as aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid, and alicyclic dicarboxylic acids. Furthermore, examples of monomers for the diol portion include 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 long-chain diols, as well as aliphatic diols such as hexanediol, and aromatic diols such as bisphenol A. In addition, the polyester may contain polyester elastomers containing ε-caprolactone or tetramethylene glycol as components. The polyester raw materials listed above may be used by mixing (dry blending) multiple homopolyesters in which carboxylic acid monomers and diol monomers are polymerized in a 1:1 ratio, or by copolymerizing two or more carboxylic acid monomers or two or more diol monomers. Alternatively, homopolyesters and copolymerized polyesters may be mixed and used. The intrinsic viscosity (IV) of the polyester raw material is not particularly limited and any can be used, but it is preferably between 0.5 and 1.2 dL / g. If the IV is less than 0.5 dL / g, the molecular weight of the raw material is too low, which can easily lead to problems such as breakage during film formation and the tensile breaking strength of the display being less than 40 MPa. On the other hand, if the IV exceeds 1.2 dL / g, the resin pressure in the extrusion process during film formation becomes too high, which is undesirable as it can easily cause filter deformation. It is more preferable that the IV is between 0.55 dL / g and 1.15 dL / g, and even more preferable that it is between 0.6 dL / g and 1.1 dL / g.

[0018] Examples of polyolefins include polypropylene (PP) and polyethylene (PE). When using polypropylene, the stereoregularity is not particularly limited and may be isotactic, syndiotactic, or atactic, and each may be present in any proportion. When using polyethylene, its density (degree of branching) is not particularly limited and may be high density (HDPE), linear low density (LLDPE), or low density (LDPE). In addition to the homopolymers mentioned above, raw materials obtained by copolymerizing two or more different monomers may also be used. Examples of monomers used in copolymerization include ethylene and α-olefins, and examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 4-methyl-1-pentene, and 4-methyl-1-hexene. The copolymerization can be random copolymerization or block copolymerization. Furthermore, in addition to the raw materials listed above, polyolefin elastomers and ionomers may also be used. The melt flow rate (MFR) of the polyolefin used as a raw material is not particularly limited and any can be used, but it is preferably between 1 and 10 g / 10 min. If the MFR is less than 1 g / 10 min, the melt viscosity of the raw material becomes too high, which leads to excessively high resin pressure during the extrusion process in film formation, making it prone to filter deformation and other problems, which is undesirable. On the other hand, if the MFR exceeds 10 g / 10 min, the molecular weight decreases drastically, which may lead to increased rupture during film formation or reduced blocking resistance. The MFR is more preferably 2 g / 10 min to 8 g / 10 min, and even more preferably 3 g / 10 min to 7 g / 10 min.

[0019] Examples of polyamides include one resin selected from polycapramid (nylon 6), polyhexamethylene adipamide (nylon 66), caprolactam / lauryl lactam copolymer (nylon 6 / 12), caprolactam / hexamethylenediammonium adipate copolymer (nylon 6 / 66), ethyleneammonium adipate / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 6 / 66 / 610), polymer of metaxylylenediamine and adipic acid (MXD-6), and hexamethylene isophthalamide / terephthalamide copolymer (amorphous nylon), or mixed raw materials containing two or more of these. Furthermore, an adhesive modification layer can be provided on the surface of a film made from the plastics listed above. Examples of materials for the adhesive modification layer include acrylic, water-soluble or water-dispersible polyester, and hydrophobic polyester obtained by graft copolymerization of acrylic. The relative viscosity (RV) of the polyamide used as a raw material is preferably between 2.2 and 4. If the RV is less than 2.2, the crystallization rate becomes too fast, which can easily lead to breakage or other problems when stretching during the film-making process. On the other hand, if the RV exceeds 4, the load on the extruder becomes too high, which can easily cause filter deformation and other problems, which is undesirable. The RV is more preferably between 2.3 and 3.9, and even more preferably between 2.4 and 3.8. In this invention, relative viscosity refers to the value measured at 25°C using a solution obtained by dissolving 0.5g of polymer in 50ml of 97.5% sulfuric acid. Of the types of plastics listed above, polyester, polypropylene, and polyethylene are preferable for the laser printing layer, from the viewpoint of mechanical strength, film formation stability, and laser printing performance. The plastic content constituting the laser-printed layer is preferably between 50% by mass and 99.95% by mass. If the plastic content falls below 50% by mass, the tensile breaking strength, as described later, is likely to fall below 40 MPa, which is undesirable. Also, if the plastic content exceeds 99.95% by mass, the relative content of the laser-printed pigment will fall below 0.05% by mass, making it likely that the difference in color L* value between the printed and unprinted areas will fall below 1.0, which is also undesirable. The plastic content is more preferably between 51% by mass and 99.9% by mass, even more preferably between 52% by mass and 99.85% by mass, and particularly preferably between 53% by mass and 99.8% by mass. When the laser-printed layer consists of multiple layers, the total plastic content of the laser-printed layer can be determined by apportioning the thickness ratio of each layer with the plastic content.

[0020] 1.2.3. Additives other than laser printing pigments The laser-printed layer constituting the packaging of the present invention may contain various additives as needed, such as waxes, antioxidants, antistatic agents, nucleating agents, viscosity reducers, heat stabilizers, coloring pigments, color inhibitors, and ultraviolet absorbers. Furthermore, if the laser-printed layer is the outermost layer, it is preferable to add fine particles as a lubricant to improve slipperiness. Any fine particles can be selected. For example, inorganic fine particles include silica, alumina, kaolin, lead white, titanium white, zeolite, zinc oxide, and lithopon, while organic fine particles include acrylic particles, melamine particles, silicone particles, cross-linked polystyrene particles, carbon black, and iron oxide. The average particle size of the fine particles can be appropriately selected within the range of 0.05 to 3.0 μm when measured with a Coulter counter. The lower limit of the fine particle content is preferably 0.01% by mass, more preferably 0.015% by mass, and even more preferably 0.02% by mass. A content of less than 0.01% by mass may result in reduced slipperiness. The upper limit is preferably 1% by mass, more preferably 0.2% by mass, and even more preferably 0.1% by mass. A value exceeding 1% by mass is undesirable because it may lead to problems such as reduced surface smoothness and blurred printability. As for the method of incorporating particles into the laser printing layer, they can be added at any stage in the manufacturing of the plastic raw material, and the same method as described in "1.2.1. Type, amount, and method of addition of laser printing pigment" above can be used.

[0021] 1.3. Thermal sealing layer As described in "1.1. Layer Structure and Thickness," the packaging of the present invention may have a laser-printed layer that also serves as a heat-sealing layer, or a separate heat-sealing layer may be provided. Here, the layer that provides the heat-sealing strength described later (including the laser-printed layer) is referred to as the heat-sealing layer. The heat-sealing layer is not particularly limited as long as it has heat-sealing properties, and conventionally known materials can be used as long as they do not depart from the spirit of the present invention. Examples of plastics that constitute the heat-sealing layer include polyester and polyolefin.

[0022] Examples of polyesters include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polytrimethylene terephthalate (PTT), polybutylene naphthalate (PBN), polylactic acid (PLA), polyethylene furanoate (PEF), and polybutylene succinate (PBS). In addition to the polyesters listed above, modified polyesters obtained by changing the monomers of the acid or diol portion may also be used. Examples of monomers for the acid portion include aromatic dicarboxylic acids such as isophthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and orthophthalic acid, as well as aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid, and alicyclic dicarboxylic acids. Furthermore, examples of monomers for the diol portion include 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 long-chain diols, as well as aliphatic diols such as hexanediol, and aromatic diols such as bisphenol A. In addition, the polyester may contain polyester elastomers containing ε-caprolactone or tetramethylene glycol as components. The polyester raw materials listed above may be used by mixing (dry blending) multiple homopolyesters in which carboxylic acid monomers and diol monomers are polymerized in a 1:1 ratio, or by copolymerizing two or more carboxylic acid monomers or two or more diol monomers. Alternatively, homopolyesters and copolymerized polyesters may be mixed and used. Copolymerized polyesters have low melting points and crystallinity, making them suitable for use in achieving thermal seal strength.

[0023] Examples of polyolefins include polypropylene (PP) and polyethylene (PE). When using polypropylene, the stereoregularity is not particularly limited and may be isotactic, syndiotactic, or atactic, and each may be present in any proportion. When using polyethylene, its density (degree of branching) is not particularly limited and may be high density (HDPE), linear low density (LLDPE), or low density (LDPE). In addition to the homopolymers mentioned above, raw materials obtained by copolymerizing two or more different monomers may also be used. Examples of monomers used in copolymerization include ethylene and α-olefins, and examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 4-methyl-1-pentene, and 4-methyl-1-hexene. The copolymerization can be random copolymerization or block copolymerization. Furthermore, in addition to the raw materials listed above, polyolefin elastomers and ionomers may also be used. Low stereoregularity or copolymerized polyolefins have low melting points and crystallinity, and can be suitably used to achieve fusible seal strength. The melt flow rate (MFR) of the polyolefin used as a raw material is not particularly limited and any can be used, but it is preferably between 1 and 10 g / 10 min. If the MFR is less than 1 g / 10 min, the melt viscosity of the raw material becomes too high, which leads to excessively high resin pressure during the extrusion process in film formation, making it prone to filter deformation and other problems, which is undesirable. On the other hand, if the MFR exceeds 10 g / 10 min, the molecular weight decreases drastically, which may lead to increased rupture during film formation or reduced blocking resistance. The MFR is more preferably 2 g / 10 min to 8 g / 10 min, and even more preferably 3 g / 10 min to 7 g / 10 min.

[0024] The heat-sealed layer may contain a lubricant to improve its slipperiness, and the concentration is preferably between 100 ppm and 2000 ppm. A lubricant concentration below 100 ppm is undesirable because it worsens the slipperiness. On the other hand, a lubricant concentration exceeding 2000 ppm is acceptable, but no further improvement in slipperiness can be expected. A lubricant concentration of 200 ppm to 1900 ppm is more preferable, and 300 ppm to 1800 ppm is even more preferable. Furthermore, the heat-sealing layer may be provided with a layer that has been treated with corona treatment, coating treatment, or flame treatment to improve surface wettability and slipperiness, and can be provided as desired without departing from the requirements of the present invention. Films made from the types of plastics listed above, using one of the following methods—unoriented, uniaxially oriented, or biaxially oriented—can be used as desired.

[0025] 1.4 Other Layers The packaging of the present invention may have layers other than the laser-printed layer and heat-sealed layer described above. The gas barrier layer (transparent, opaque) and printed layer described in "1.1. Layer composition and thickness" above will be explained below.

[0026] 1.4.1. Gas Barrier Layer The gas barrier layer that can be arbitrarily laminated onto the packaging of the present invention is preferably composed of an inorganic thin film mainly composed of a metal or metal oxide. Furthermore, in addition to the gas barrier made of the inorganic thin film, there may be an anchor coat layer provided below the inorganic thin film layer (between the plastic film and the inorganic thin film) and an overcoat layer provided on top of the inorganic thin film layer. By providing these layers, improvements in adhesion with the gas barrier layer and improved gas barrier properties can be expected.

[0027] The raw materials for the gas barrier layer are not particularly limited, and conventionally known materials can be used. They can be appropriately selected according to the purpose in order to satisfy the desired gas barrier properties. Examples of raw materials 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. Examples of applicable inorganic compounds include oxides, nitrides, carbides, and fluorides. These inorganic materials or inorganic compounds may be used individually or in combination. When the gas barrier layer is transparent, silicon dioxide (SiOx) and aluminum oxide (AlOx) can be used individually (as a single element) or in combination (as a binary element). When the inorganic compound consists of a binary of silicon dioxide and aluminum oxide, the aluminum oxide content is preferably 20% by mass or more and 80% by mass or less, and more preferably 25% by mass or more and 70% by mass or less. If the aluminum oxide content is 20% by mass or less, the density of the gas barrier layer will decrease, which may reduce its gas barrier properties, and this is undesirable. Also, if the aluminum oxide content is 80% by mass or more, the flexibility of the gas barrier layer will decrease, making it more prone to cracking, which may result in a decrease in gas barrier properties, and this is undesirable.

[0028] For metal oxides used in the gas barrier layer, an oxygen / metal elemental ratio of 1.3 or higher and less than 1.8 is preferable because it minimizes variations in gas barrier properties and consistently provides excellent gas barrier performance. The oxygen / metal elemental ratio can be determined by measuring the amounts of each element, oxygen and metal, using X-ray photoelectron spectroscopy (XPS) and calculating the oxygen / metal elemental ratio. The thickness of the gas barrier layer that can be preferably used in the packaging of the present invention is preferably 2 nm to 100 nm when a metal or metal oxide is deposited as the gas barrier layer. If the thickness of this layer is less than 2 nm, the gas barrier properties tend to decrease, which is undesirable. On the other hand, if the thickness of this layer exceeds 100 nm, there is no corresponding improvement in gas barrier properties, and the manufacturing cost increases, which is also undesirable. The thickness of the inorganic thin film layer is more preferably 5 nm to 97 nm, and even more preferably 8 nm to 94 nm.

[0029] When the gas barrier layer is a metal foil, it is preferable that the thickness of the metal foil is 3 μm or more and 100 μm or less. When the thickness of this layer is less than 3 μm, the gas barrier property tends to decrease, which is not preferable. On the other hand, even if the thickness of this layer exceeds 100 μm, there is no corresponding improvement effect on the gas barrier property, and the manufacturing cost increases, which is not preferable. The thickness of the inorganic thin film layer (metal foil) is more preferably 5 μm or more and 97 μm or less, and still more preferably 8 μm or more and 94 μm or less. When the gas barrier layer is opaque, the gas barrier layer can be formed by bonding an aluminum foil or vapor-depositing aluminum. It is preferable that the thickness of the aluminum foil is 1 μm or more and 100 μm or less.

[0030] The gas barrier laminate thus produced has a water vapor transmission rate of 0.05 [g / (m 2 ·d)] or more and 4 [g / (m 2 ·d)] or less, which is preferable. When the water vapor transmission rate exceeds 4 [g / (m 2 ·d)], the shelf life of the contents is shortened when the gas barrier laminate is used as a package containing the contents, which is not preferable. On the other hand, when the water vapor transmission rate is smaller than 0.05 [g / (m 2 ·d)], the gas barrier property is improved and the shelf life of the contents is prolonged, which is preferable. However, according to the current state of the art, 0.05 [g / (m 2 ·d)] is the lower limit. It can be said that it is sufficiently practical even when the lower limit of the water vapor transmission rate is 0.05 [g / (m 2 ·d)]. The upper limit of the water vapor transmission rate is 3.8 [g / (m 2 ·d)], which is preferable, and more preferably 3.6 [g / (m 2 ·d)]. In addition, the gas barrier laminate has an oxygen transmission rate of 0.05 [cc / (m 2 ·d·atm)] or more and 4 [cc / (m 2 ·d·atm)] or less, which is preferable. When the oxygen transmission rate exceeds 4 [cc / (m 2If the oxygen permeability exceeds 0.05 [cc / (m³)], the shelf life of the contents will be shortened, which is undesirable. On the other hand, an oxygen permeability of 0.05 [cc / (m³)] is undesirable. 2 A value smaller than 0.05 [cc / (m³) is preferable because it increases gas barrier properties and extends the shelf life of the contents, but with the current level of technology, an oxygen permeability of 0.05 [cc / (m³) is preferable. 2 The lower limit is 0.05 [cc / (m³)]. 2 Even if it is d·atm), it can be said to be sufficient for practical purposes. The upper limit of oxygen permeability is 3.8 [cc / (m³). 2 It is preferable that it is 3.6[cc / (m)) 2 It is more preferable if it is (d·atm).

[0031] Furthermore, an overcoat layer can be provided on the aforementioned gas barrier laminate for purposes such as improving abrasion resistance and further enhancing gas barrier properties. The type of overcoat layer is not particularly limited, but conventionally known materials such as compositions consisting of urethane resin and silane coupling agents, compounds consisting of organosilicon and its hydrolysates, and water-soluble polymers having hydroxyl or carboxyl groups can be used, and can be appropriately selected according to the purpose in order to satisfy the desired gas barrier properties, etc. Furthermore, the overcoat layer may contain one or more additives for the purpose of providing antistatic properties, UV absorption, coloring, thermal stability, slipperiness, etc., to the extent that it does not impair the objectives of the present invention, and the types and amounts of additives can be appropriately selected according to the desired objectives.

[0032] 1.4.2.Printing layer In addition to laser printing, the packaging of the present invention may also be provided with characters or designs to enhance its aesthetic appeal. Known materials such as gravure printing inks or flexographic printing inks can be used to constitute these characters and designs. The number of printed layers may be one or multiple. To improve aesthetic appeal by using multiple colors, it is preferable to have multiple printed layers. The printed layers may be located at the outermost layer or in the middle layers.

[0033] 2. Characteristics of the packaging 2.1. Difference in color L* value (non-printed area - printed area) The packaging of the present invention requires that the absolute difference in the color L* values ​​between the printed and unprinted areas (hereinafter sometimes simply referred to as "difference in L* values") be between 1.0 and 10.0. If this difference is less than 1.0, the color tones of the printed and unprinted areas become too similar, making it difficult to see the print. On the other hand, if the difference in L* values ​​exceeds 10.0, the print becomes easier to see, but this requires increasing the laser irradiation power, which increases damage to the packaging and makes problems such as holes more likely to occur, so it is undesirable. A difference in L* values ​​of 1.5 to 9.5 is more preferable, and a difference of 2.0 to 9.0 is even more preferable.

[0034] 2.2. Heat-seal strength The packaging of the present invention must have a heat-seal strength of 5N / 15mm or more and 40N / 15mm or less. A seal strength of less than 5N / 15mm is undesirable because the sealed portion will easily peel off. A seal strength of 6N / 15mm or more is more preferable, and 7N / 15mm or more is even more preferable. A higher seal strength is preferable because it improves the sealing performance of the packaging, but the upper limit that can be obtained at present is about 40N / 15mm. An upper limit of seal strength of 30N / 15mm is sufficient for practical purposes.

[0035] 2.3. Print size The size of the laser-formed print on the packaging of the present invention is preferably such that the height or width is 0.2 mm or more and 100 mm or less. The resolution of the human eye is said to be about 0.2 mm, and if the character size is less than 0.2 mm, the difference in color L* values ​​tends to be less than 1.0, making it difficult to recognize the print. On the other hand, if the print size exceeds 100 mm, it is preferable as it makes it easier to recognize the print, but if the print size is too large, the amount of information that can be written on the packaging becomes small, which is undesirable. The print size is more preferably 0.5 mm or more and 90 mm or less, and even more preferably 1 mm or more and 80 mm or less.

[0036] 2.4. Thermal shrinkage rate Preferably, when the packaging of the present invention is cut from any portion where the innermost layers are not sealed and treated in hot air at 120°C for 30 minutes, the thermal shrinkage rate in at least one direction of the packaging's plane is -10% or more and 10% or less. A thermal shrinkage rate exceeding 10% is undesirable because it causes significant deformation when placed in a high-temperature environment, making it impossible to maintain the original shape. On the other hand, a thermal shrinkage rate below -10% means that the packaging stretches, which is undesirable because, similar to the case of a high thermal shrinkage rate, it becomes difficult for the packaging to maintain its original shape. More preferably, the thermal shrinkage rate of the packaging is -9% or more and 9% or less, and even more preferably -8% or more and 8% or less.

[0037] 2.5. Tensile breaking strength The packaging of the present invention preferably has a tensile breaking strength of 40 MPa or more and 400 MPa when any portion that is not heat-sealed is cut off and measured in at least one direction on the plane of the packaging. A tensile breaking strength below 40 MPa is undesirable because the packaging will easily break due to external tension. The lower limit of the tensile breaking strength is more preferably 50 MPa, and even more preferably 60 MPa. On the other hand, a tensile breaking strength exceeding 400 MPa is desirable in terms of mechanical strength, but 400 MPa is the upper limit in the art of the present invention. A tensile breaking strength of 300 MPa is also sufficient for practical purposes.

[0038] 3.Manufacturing conditions 3.1. Laser Printing Layer The laser-printed layer constituting the packaging of the present invention can be manufactured by the methods and conditions exemplified below. 3.1.1. Raw material mixing and supply In manufacturing the laser-printed layer contained in the packaging of the present invention, it is necessary to add the laser-printed pigment described in "1.2.1. Type, amount, and method of addition of laser-printed pigment" above. Since laser printing pigments are metals, their specific gravity is usually greater than that of the resin that makes up the film. When two or more raw materials with different specific gravities are mixed and fed into an extruder, variations (segregation) in the supply of raw materials are likely to occur. To prevent this variation, it is preferable to take measures such as installing a stirrer in the piping or hopper directly above the extruder, or inserting piping (inner pipes) into the hopper directly above the extruder that is filled with base resin to supply the laser printing pigment, or installing a shield to reduce the particle pressure of the raw materials in each raw material hopper before melt extrusion.

[0039] 3.1.2. Molten Extrusion The laser-printed layer can be obtained by melt-extruding the raw materials supplied in "3.1.1. Raw Material Mixing and Supply" from an extruder to form an unstretched film, which is then obtained through the following predetermined process. When laminating the laser-printed layer and the heat-sealed layer, it is preferable to laminate them during the extrusion process. The preferred lamination method is co-extrusion, in which the resins that will be the raw materials for each layer are melt-extruded using separate extruders and joined together using a feed block or the like in the middle of the resin flow path. Alternatively, an extrusion lamination method can be used in which the resin that will become the seal layer is melt-extruded from a slot die and laminated at any step from after the laser-printed layer is extruded until winding. Known methods can be used for melt extrusion of the raw material resin, and a method using an extruder equipped with a barrel and a screw is preferred. In the case of raw materials that decompose due to the influence of moisture during melting (such as polyester), it is preferable to dry them beforehand using a dryer such as a hopper dryer or paddle dryer, or a vacuum dryer, until the moisture content is 100 ppm or less, more preferably 90 ppm or less, and even more preferably 80 ppm or less. After drying the raw materials in this way, an unstretched film can be obtained by rapidly cooling the resin melted by the extruder. Any existing method such as the T-die method or the tubular method can be used for extrusion.

[0040] Subsequently, an unstretched film can be obtained by rapidly cooling the film melted by extrusion. A suitable method for rapidly cooling the molten resin is to cast the molten resin from a die onto a rotating drum and rapidly cool and solidify it to obtain a substantially unoriented resin sheet. The film to be used as the printing layer may be made using any of the following methods: unstretched, uniaxially stretched (stretched in at least one direction, either the longitudinal or transverse direction), or biaxially stretched. However, considering mechanical strength, uniaxial stretching is preferable, and biaxial stretching is more preferable. By using a stretched film, it is possible to prevent a decrease in mechanical strength due to the use of laser printing pigments and improve abrasion resistance. The following describes a sequential biaxial stretching method using longitudinal-transverse stretching, where longitudinal stretching is performed first, followed by transverse stretching. While the explanation will focus on this, reversing the order to lateral-longitudinal stretching is also acceptable, as it only changes the primary orientation direction. Furthermore, simultaneous biaxial stretching, where both longitudinal and lateral stretching are performed simultaneously, is also acceptable.

[0041] 3.1.3. First (Vertical) Extension For stretching in the first direction (longitudinal or longitudinal direction), the film is preferably introduced into a longitudinal stretcher having multiple rolls arranged in a continuous pattern. For longitudinal stretching, it is preferable to preheat the film with a preheating roll. The preheating temperature should be set between the glass transition temperature (Tg) or melting point (Tm) of the plastic constituting the film and 50°C. If the preheating temperature is lower than Tg, it becomes difficult to stretch the film in the longitudinal direction and breakage is more likely to occur, which is undesirable. Also, if the heating temperature is higher than 50°C, the film tends to stick to the rolls and become prone to wrapping, which is also undesirable. Longitudinal stretching is performed when the film reaches Tg~Tm+50℃. The longitudinal stretching ratio should be between 1x and 5x. Since 1x means no longitudinal stretching has been performed, the longitudinal stretching ratio should be 1x to obtain a transversely oriented film, and 1.1x or higher to obtain a biaxially oriented film. A longitudinal stretching ratio of 1.1x or higher is preferable because it creates cavities in the printed layer. There is no upper limit to the longitudinal stretching ratio, but if the longitudinal stretching ratio is too high, breakage is likely to occur during the subsequent transverse stretching, so it is preferable to keep it at 10x or lower. A longitudinal stretching ratio of 1.2x to 9.8x is more preferable, and 1.4x to 9.6x is even more preferable.

[0042] 3.1.4.Second (lateral) stretching After the first (longitudinal) stretching, it is preferable to perform transverse stretching at a stretching ratio of approximately 2 to 13 times at Tg to Tm + 50°C while holding both ends of the film in the width direction (direction perpendicular to the longitudinal direction) with clips inside the tenter. It is preferable to preheat before performing transverse stretching, and preheating should be carried out until the surface temperature of the labeling material or packaging reaches Tg to Tm + 50°C. The lateral stretching ratio is more preferably between 2.2 and 12.8 times, and more preferably between 2.4 and 12.6 times. Note that the stretching speed differs between longitudinal and lateral stretching (longitudinal stretching is faster), so the preferred range of stretching ratios differs. The area ratio obtained by multiplying the longitudinal and lateral stretching ratios is preferably between 2.2 and 64 times. After transverse stretching, it is preferable to pass the film through an intermediate zone where no active heating is performed. The temperature in the final heat treatment zone is higher than in the transverse stretching zone of the tenter, so if an intermediate zone is not provided, the heat from the final heat treatment zone (hot air itself and radiant heat) will flow into the transverse stretching process. In this case, the temperature in the transverse stretching zone will not be stable, resulting in variations in physical properties. Therefore, it is preferable to pass the transversely stretched film through an intermediate zone for a predetermined time before performing the final heat treatment. In this intermediate zone, it is important to block the accompanying flow associated with the movement of the film and the hot air from the transverse stretching zone and the final heat treatment zone so that when a strip of paper is hung down without the film passing through, the strip hangs almost completely vertically. A passage time of about 1 to 5 seconds in the intermediate zone is sufficient. If it is shorter than 1 second, the length of the intermediate zone will be insufficient, and the heat blocking effect will be inadequate. On the other hand, a longer intermediate zone is preferable, but if it is too long, the equipment will become large, so about 5 seconds is sufficient.

[0043] 3.1.5. Heat Treatment After passing through the intermediate zone, it is preferable to heat-treat the film in the heat treatment zone at 100 to 280°C. Heat treatment promotes crystallization of the film, which not only reduces the thermal shrinkage rate that occurred during the stretching process but also tends to increase the tensile breaking strength. Heat treatment temperatures below 100°C are undesirable because they tend to increase the thermal shrinkage rate of the film. On the other hand, heat treatment temperatures exceeding 280°C are undesirable because they tend to melt the film and tend to decrease the tensile breaking strength. Heat treatment temperatures of 110 to 270°C are more preferable, and 120 to 260°C are even more preferable. The passage time through the heat treatment zone is preferably between 2 seconds and 20 seconds. If the passage time is less than 2 seconds, the film will pass through the heat treatment zone before its surface temperature reaches the set temperature, rendering the heat treatment ineffective. The longer the passage time, the more effective the heat treatment becomes, so 5 seconds or more is even more preferable. However, increasing the passage time would require larger equipment, so in practical terms, 20 seconds or less is sufficient. During heat treatment, the thermal shrinkage rate in the width direction can be reduced by shortening the distance between tenter clips by an arbitrary factor (relaxation in the width direction). Therefore, in the final heat treatment, it is preferable to perform relaxation in the width direction within the range of 0% to 10% (a relaxation rate of 0% means no relaxation is performed). Although the shrinkage rate in the width direction decreases as the relaxation rate in the width direction increases, the upper limit of the relaxation rate (the shrinkage rate in the width direction of the film immediately after transverse stretching) is determined by the raw materials used, the stretching conditions in the width direction, and the heat treatment temperature, so relaxation cannot be performed beyond this limit. In the laser printing layer that constitutes the display material of the present invention, the upper limit of the relaxation rate in the width direction is 10%. Furthermore, during heat treatment, it is also possible to shorten the distance between clips in the longitudinal direction by an arbitrary factor (relaxation in the longitudinal direction).

[0044] 3.1.6. Cooling After passing through the heat treatment zone, it is preferable to cool the film in the cooling zone using cooling air at a temperature of 10°C to 50°C for a period of 2 to 20 seconds. Then, by cutting and removing the ends of the film while winding it up, you can obtain a film roll.

[0045] 3.2. Gas Barrier Layer The following describes a method for manufacturing a gas barrier layer that can be optionally provided on the packaging of the present invention. The method for forming the gas barrier layer is not particularly limited, and known manufacturing methods can be used as long as they do not impair the objectives of the present invention. Among known manufacturing methods, vapor deposition is preferred. Examples of vapor deposition methods include PVD methods (physical vapor deposition) such as vacuum deposition, sputtering, and ion plating, or CVD methods (chemical vapor deposition). Among these, vacuum deposition and physical vapor deposition are preferred, and vacuum deposition is particularly preferred from the viewpoint of production speed and stability. As a heating method in vacuum deposition, resistance heating, high-frequency induction heating, electron beam heating, etc., can be used. In addition, reactive vapor deposition using means such as introducing oxygen, nitrogen, water vapor, etc. as a reactive gas, or adding ozone, or ion assist may be used. Furthermore, the film formation conditions can be changed as long as they do not impair the objectives of the present invention, such as applying a bias to the substrate or raising or cooling the substrate temperature.

[0046] This section describes a method for forming a gas barrier layer using vacuum deposition. When forming the gas barrier layer, the film that will form the packaging body of the present invention (such as a laser-printed layer) is transported to the gas barrier layer manufacturing apparatus via metal rolls. An example of the gas barrier layer manufacturing apparatus configuration is a winding roll, a coating drum, a take-up roll, an electron beam gun, a crucible, and a vacuum pump. The film is set on the winding roll, passes through the coating drum, and is wound up on the take-up roll. The film's pass line (inside the gas barrier layer manufacturing apparatus) is depressurized by a vacuum pump, and the inorganic material set in the crucible is evaporated by a beam emitted from the electron gun and deposited onto the film as it passes through the coating drum. During the deposition of the inorganic material, the film is heated, and tension is also applied between the winding roll and the take-up roll. If the temperature applied to the film is too high, not only will the thermal shrinkage of the film increase, but softening will also progress, making it more susceptible to stretching deformation due to tension. Furthermore, a large temperature drop (cooling) of the film after the vapor deposition process leads to a large amount of shrinkage after expansion (different from thermal shrinkage), causing cracks to form in the gas barrier layer and making it difficult to achieve the desired gas barrier properties, which is undesirable. On the other hand, a lower temperature applied to the film is preferable because it suppresses film deformation, but the amount of evaporation of inorganic material decreases, which reduces the thickness of the gas barrier layer, raising concerns that the desired gas barrier properties may not be met. The temperature applied to the film is preferably 100°C to 180°C, more preferably 110°C to 170°C, and even more preferably 120°C to 160°C.

[0047] 3.3. Overcoat layer The following describes a method for manufacturing an overcoat layer that can be optionally provided on the packaging of the present invention. When forming the overcoat layer, the film (such as the laser-printed layer) that will form the packaging of the present invention is transported to the coating equipment via metal rolls. Examples of equipment configurations include an unwinding roll, a coating process, a drying process, and a winding process. During the overcoat process, the film set on the unwinding roll is guided via metal rolls through the coating and drying processes, and finally to the winding roll. The coating method is not particularly limited, and conventionally known methods such as gravure coating, reverse coating, dipping, raw coating, air knife coating, comma coating, screen printing, spray coating, gravure offset, die coating, and bar coating can be used and selected as appropriate according to the desired purpose. Among these, gravure coating, reverse coating, and bar coating are preferred from the viewpoint of productivity. For the drying method, one 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 film is heated, and tension is also applied between metal rolls. If the temperature at which the film is heated in the drying process is too high, not only will the thermal shrinkage of the film increase, but softening will also progress, making it easier for stretch deformation due to tension to occur, and cracks are more likely to occur in the gas barrier layer of the film. Furthermore, the temperature of the film drops (cools) significantly after exiting the drying process, and the amount of shrinkage after expansion (different from thermal shrinkage) increases accordingly, causing cracks in the gas barrier layer and overcoat layer, making it difficult to achieve the desired gas barrier properties, which is undesirable. On the other hand, the lower the temperature at which the film is heated, the more the deformation of the film is suppressed, which is preferable, but the solvent of the coating liquid will not dry easily, raising concerns that the desired gas barrier properties may not be achieved. The temperature at which the film is heated is preferably 60°C to 200°C, more preferably 80°C to 180°C, and even more preferably 100°C to 160°C.

[0048] 3.5. Bag making conditions The method for forming the packaging of the present invention requires the use of heat sealing. Heat sealing is achieved, for example, by heat sealing the left and right edges of the packaging body with a heated blade (heat-sealing blade) (side seal or side weld). However, there are no particular restrictions on the shape of the packaging body; any shape such as rectangle, square, or triangle can be used. The equipment and conditions used for heat sealing can be any conventionally known equipment and conditions, and are not particularly limited as long as they do not deviate from the spirit of the present invention. Examples of heat-sealing conditions include the heat-sealing blade temperature, blade angle, and bag-making speed (heat-sealing blade stroke frequency). Specifically, the heat-sealing blade temperature is preferably between 300°C and 450°C. The heat-sealing blade temperature varies depending on the melting point of the film used, but the melting points of polyester and polyolefin, as mentioned above, are between 110°C and 300°C, so it is necessary to set the temperature higher than this. A heat-sealing blade temperature below 300°C is undesirable because it increases the likelihood of heat-sealing defects. On the other hand, a heat-sealing blade temperature exceeding 450°C reduces the likelihood of heat-sealing defects, but it is undesirable because the film in the heat-sealed area is more prone to deformation due to thermal shrinkage. A heat-sealing blade temperature of 310°C to 440°C is more preferable, and 320°C to 430°C is even more preferable. The cutting edge angle of the cutting blade should be between 50° and 130° with respect to the horizontal direction (the direction in which the film flows). The following is preferable. If the blade tip angle is less than 50° or more than 130°, the heat transfer efficiency to the film cutting area will be poor, reducing the heat sealing strength, which is undesirable. The blade tip angle is more preferably 52° to 128°, and even more preferably 54° to 126°. The bag-making speed is preferably 60 bags / minute or more and 240 bags / minute or less. A bag-making speed of less than 60 bags / minute is undesirable because it drastically reduces the productivity of the packaging. On the other hand, a bag-making speed of 240 bags / minute is undesirable because it increases the likelihood of sealing defects. A bag-making speed of 65 bags / minute or more and 235 bags / minute or less is more preferable, and 70 bags / minute or more and 230 bags / minute or less is even more preferable.

[0049] 3.6. Laser Printing Conditions Examples of laser types (wavelengths) that can be used for laser printing on the packaging of the present invention include CO2 lasers (10600nm), YAG lasers (1064nm), YVO4 lasers (1064nm), fiber lasers (1064, 1090nm), green lasers (532nm), and UV lasers (355nm). Among these, the type of laser used for printing in the present invention is not particularly limited, but CO2 lasers are often used to burn through plastics and are often used for purposes other than printing, which is the essence of the present invention, so they are not preferred as a laser source. YAG lasers, YVO4 lasers, fiber lasers, green lasers, and UV lasers are preferred as laser sources, and YAG lasers, fiber lasers, and UV lasers are more preferred. Commercially available laser printing equipment can be used, with representative examples including the Brother Industrial Printing LM-2550 (YAG laser), Omron MX-Z2000H-V1 (fiber laser), Trotec 8028 Trotec Speedy 100 flexx (fiber laser), Keyence MD-X1000 (YVO4 laser), and MD-U1000C (UV laser). Laser printing conditions vary depending on the equipment manufacturer and model, and also differ depending on the film being printed on, so it is difficult to generalize. However, using the Keyence MD-U1000C (UV laser, wavelength 355nm) as an example, the conditions are as follows.

[0050] The laser power is preferably 20% to 80% of the maximum device specification of 13W. An output of less than 20% is undesirable because it reduces print density and visibility. An output of more than 80% is undesirable because it can cause holes in the display surface. An output of 25% to 75% is more preferable, and 30% to 70% is even preferable. The pulse frequency is preferably 10kHz to 100kHz. A frequency below 10kHz is undesirable because the laser energy per pulse becomes high, making it easy for the thickness reduction rate of the printed area to exceed 80 vol%. Conversely, if the frequency exceeds 100kHz, it is easier to keep the thickness reduction rate of the printed area below 80 vol%, but it may be difficult to keep the difference in color L* values ​​of the printed area at 1 or more. A frequency of 15kHz to 95kHz is more preferable, and 20kHz to 90kHz is even preferable. The scan speed is preferably 10mm / sec to 3000mm / sec. If the scan speed falls below 10 mm / second, the printing speed decreases drastically, which is undesirable as it slows down the production speed of the display units. On the other hand, if the scan speed exceeds 3000 mm / second, the print density decreases, making it difficult to maintain a color L* value difference of 1 or more, which is also undesirable. A scan speed of 100 mm / second to 2900 mm / second is more preferable, and 200 mm / second to 2800 mm / second is even more preferable. [Examples]

[0051] Next, the present invention will be specifically described using examples and comparative examples. However, the present invention is not limited in any way to the embodiments of these examples, and can be modified as appropriate without departing from the spirit of the invention. <Polyolefin raw materials> <Polyolefin A> As polyolefin A, we used FS2011DG3 (manufactured by Sumitomo Chemical Co., Ltd.), which is homopolypropylene. <Polyolefin B> As polyolefin B, SPX78J1 (manufactured by Sumitomo Chemical Co., Ltd.), which is a propylene-butene-1 copolymer (copolymerization ratio 25 mol%), was used. <Polyolefin C> Polyolefin C was prepared by kneading 30% by mass of CaCO3 and 5% by mass of TiO2 as laser printing pigments into polyolefin A. <Polyolefin D> Polyolefin D was prepared by kneading 5% by mass of TOMATEC COLOR42-920A (main component Bi2O3, manufactured by Tokan Material Technology Co., Ltd.) as a laser pigment into polyolefin A. <Polyolefin E> Polyolefin E was prepared by kneading 15,000 ppm of SiO2 as a lubricant into polyolefin A.

[0052] <Polyester raw materials> [Polyester A] As polyester A, RE553 (manufactured by Toyobo Co., Ltd.), which is homopolyethylene terephthalate, was used. [Polyester B] As polyester B, we used SR173 (manufactured by Toyobo Co., Ltd.), which is a neopentyl glycol copolymer (copolymerization ratio 30 mol%). [Polyester C] Polyester C was prepared by kneading 50% by mass of TiO2 into polyester A. [Polyester D] Polyester D was prepared by kneading 5% by mass of TOMATEC COLOR42-920A (main component Bi2O3, manufactured by Tokan Material Technology Co., Ltd.) as a laser pigment into Polyester A. [Polyester E] As polyester E, RE555 (manufactured by Toyobo Co., Ltd.), which is homopolyethylene terephthalate with 7000 ppm of SiO2 kneaded into it, was used. Table 1 shows the composition of each polyolefin and polyester raw material.

[0053] [Table 1]

[0054] [Example 1] Polyolefin A, polyolefin D, and polyolefin E were mixed in a mass ratio of 92:3:5 as the raw materials for layer A, and polyolefin B and polyolefin E were mixed in a mass ratio of 95:5 as the raw materials for layer B. The mixed raw materials for layers A and B were each fed into separate screw extruders, melted, and extruded through T-dies. The molten resins were joined together by a feed block midway through the flow path and extruded from the T-dies. The extruded resins were then taken up while being cooled on chill rolls set to a surface temperature of 30°C to obtain unstretched laminated films. The extrusion rate of the laminated films was adjusted so that the thickness ratio of layers A to B was 95 / 5. The unstretched laminated film, obtained by cooling and solidifying, was guided to a longitudinal stretching machine with multiple rolls arranged in a series. After preheating on a preheating roll until the film temperature reached 125°C, it was stretched to 3.8 times its original size. After longitudinal stretching, the film was guided to a transverse stretching machine (tenter) and preheated for 8 seconds until the surface temperature reached 155°C. Then, it was stretched 8.6 times in the width direction (transverse direction). The transversely stretched film was then guided directly to the intermediate zone and passed through for 1.0 second. In the intermediate zone of the tenter, the hot air from the heat treatment zone and the hot air from the transverse stretching zone were blocked so that when a strip of paper was hung down without the film passing through, the strip of paper would hang almost completely vertically. Subsequently, the film that had passed through the intermediate zone was guided to the heat treatment zone and heat-treated at 160°C for 9 seconds. At the same time as the heat treatment, the clip spacing in the width direction of the film was narrowed, thereby performing a 3% relaxation treatment in the width direction. After passing through the final heat treatment zone, the film was cooled with 30°C cooling air for 5 seconds. By cutting off both edges and winding the film into a roll with a width of 600 mm, a biaxially oriented film with a thickness of 30 μm was continuously produced over a predetermined length.

[0055] The film was unfurled from the obtained film roll and continuously folded in half using a half-folding machine so that the B layers overlapped and the folds aligned with the direction of flow. This folded film was then guided to a heat-sealing machine (Kyoei Printing Machinery Materials Co., Ltd.: PP500 model) and continuously heat-sealed along the width direction of the film to create A4 size (210 mm in the flow direction x 300 mm in the width direction) packaging. The heat-sealing conditions were a heat-sealing blade temperature of 400°C, a blade angle of 60°C, and a bag-making speed of 120 pieces / minute. The resulting packaging was then treated with a 1064nm fiber laser (Trotec Speedy 100 flexx laser marker 8028, manufactured by Trotec). A display was created by printing "12345ABCDE" in the center of a film using a pulse frequency of 30kHz, a scan speed of 1500mm / min, and an output of 80%. Each character measured approximately 8mm in height and 5mm in width. Table 2 shows the manufacturing conditions and evaluation results for the laser-printed packaging materials that were produced.

[0056] [Examples 2-4] Examples 2 to 4 were prepared in the same manner as Example 1, with various conditions modified. Table 2 shows the manufacturing conditions for laser printing and the evaluation results for each example.

[0057] [Comparative Example 1] A laminate was formed by continuously coating one side of a polypropylene film, Pylen Film (registered trademark) P5562-30μm manufactured by Toyobo Co., Ltd., with a white ink layer using a gravure roll to create a laser-printed layer. The white ink layer was prepared by mixing methyl ethyl ketone, isopropyl alcohol, polyurethane, and TiO2 in a ratio of 11:3:38:48% by mass. The thickness of the laser-printed layer was 3μm. By cutting and removing both edges of this laminate and winding it into a roll with a width of 600mm, a film with a thickness of 33μm was continuously produced over a predetermined length. The film was unfurled from the obtained film roll and continuously folded in half using a half-folding machine so that the TiO2 coated surfaces overlapped and the folds aligned with the direction of flow. This folded film was then guided to a heat-sealing machine (Kyoei Printing Machinery Materials Co., Ltd.: PP500 model) and continuously heat-sealed along the width direction of the film to create A4 size (210 mm in the flow direction x 297 mm in the width direction) packaging. The heat-sealing conditions were a heat-sealing blade temperature of 400°C, a blade angle of 60°C, and a bag-making speed of 120 pieces / minute. The resulting packaging was printed with "12345ABCDE" in the center of the film using a 355nm wavelength UV laser (Keyence MD-U1000C laser marker) at a pulse frequency of 40kHz, a scan speed of 2000mm / min, and 30% output. Each character measured approximately 3mm in height and 3mm in width. Table 2 shows the manufacturing conditions and evaluation results for the laser-printed packaging materials that were produced.

[0058] [Comparative Example 2] The TiO2-coated laminate obtained in the same manner as in Comparative Example 1 was continuously folded in half using a half-folding machine so that the folds aligned with the flow direction, with the opposite side of the TiO2-coated surface overlapping. Heat sealing and laser printing were then performed in the same manner as in Comparative Example 1. The manufacturing conditions and evaluation results of the laser-printed packaging bodies are shown in Table 2.

[0059] [Comparative Example 3] A polypropylene film, Pylen Film (registered trademark) P5562-30μm manufactured by Toyobo Co., Ltd., was continuously folded in half using a half-folding machine so that one side overlapped and the fold was aligned with the direction of flow. Heat sealing and laser printing were then performed in the same manner as in Comparative Example 1. The manufacturing conditions and evaluation results of the laser-printed packaging bodies are shown in Table 2.

[0060] <Evaluation method for packaging> The evaluation method for the packaging was as follows: For non-printed samples, portions were cut out at least 1 mm away from the printed or heat-sealed areas and used as samples.

[0061] [thickness] Five points were measured using a micrometer (Millitron 1254D, manufactured by Feinpluf), and the average value was calculated.

[0062] [Color L* value (printed area, non-printed area)] A spectrophotometer (ZE-6000, manufactured by Nippon Denshoku Co., Ltd.) was used to measure the L* values ​​of both the printed and unprinted areas of a single film sample using the reflection method. The measurement method for the printed area is as follows: A 3cm square sample was cut out so that all the letters "B" from the printed "12345ABCDE" were included, and measured (it was acceptable for other letters to be included). A 6φ sample stage (with an opening of approximately 1cm in diameter where the measurement light hits) and a 6φ eyepiece were used as the light source for the colorimeter, and the letters "B" were positioned so that they fit within the opening of the sample stage. If the printing does not fit within the opening of the sample stage (overflows), the sample stage may be changed as needed (e.g., 10φ, 30φ, etc.). Even if the printing overflows, it is sufficient if a part of the printing enters the opening of the sample stage and is illuminated by the measurement light. Furthermore, for the non-printed areas, a 3cm square sample was cut from the unprinted portion, and the color L* value was measured using a 6φ eyepiece and sample stage of the colorimeter. Note that the eyepiece and sample stage of the colorimeter may be changed to 10φ, 30φ, etc., as needed, and in that case, the sample size can be any size as long as it covers the opening of the sample stage (preventing leakage of measurement light).

[0063] [Heat-sealing strength] Ten samples were taken from arbitrary positions on the packaging, each measuring 15 mm in the direction along the heat-sealed seam (sample width) and 100 mm in the direction perpendicular to the sample width (tensile direction), from the heat-sealed section (300 mm on each side x 2 = 600 mm total). In accordance with JIS Z1707, these samples were opened 180 degrees and both ends were set in a universal tensile testing machine "Autograph AG-Xplus" (manufactured by Shimadzu Corporation). A tensile test was performed with a chuck distance of 50 mm and a tensile speed of 200 mm / min, and the peel strength at which the heat-sealed section broke was measured. The maximum peel strength was defined as the heat-sealed strength, and the strength per 15 mm of sample width (N / 15 mm) was recorded. The average value of the 10 samples was taken as the average heat-sealed strength. If the size of the packaging prevents the sample from being cut to a length of 100 mm or more, a shorter length (e.g., 50 mm) may be used. In this case, the distance between the chucks may be 50 mm or less (for example, if the sample length is 50 mm, the distance between the chucks is 40 mm) as long as at least 5 mm of length is provided on one side of the chuck to grip the sample.

[0064] [Print size] Of the characters printed as "12345ABCDE", the height and width of "345ABC" were visually determined using a stainless steel straight ruler (KOKUYO TZ-RS15). The print size was measured in 0.5mm increments, and the average value was used as the print size. If the print size was less than 0.5mm, the print size was measured separately using a HIROX RH-2000 digital microscope. The software included with the HIROX RH-2000 digital microscope was used to measure the print size.

[0065] [Thermal shrinkage rate] The film was cut into 10cm x 10cm squares and exposed to 120°C hot air for 30 minutes without load to shrink it. The lengthwise and widthwise dimensions of the film were then measured, and the shrinkage rate in each direction was calculated according to Equation 1 below. The measurement was performed twice, and the average value was calculated. Shrinkage rate = {(Length before shrinkage - Length after shrinkage) / Length before shrinkage} × 100 (%) Equation 1

[0066] [Tensile breaking strength] In accordance with JIS K7113, a strip-shaped film sample was prepared with a measurement direction of 140 mm and a direction perpendicular to the measurement direction (film width direction) of 20 mm. Using a universal tensile testing machine "Autograph AG-Xplus" (manufactured by Shimadzu Corporation), both ends of the test piece were gripped with chucks, 20 mm on each side (chuck distance 100 mm), and a tensile test was performed under conditions of ambient temperature 23°C and tensile speed 200 mm / min. The strength (stress) at the time of tensile fracture was defined as the tensile fracture strength (MPa). The measurement direction was the longitudinal direction and the width direction. [Visual evaluation of the printed area] The legibility of the letters "12345ABCDE" printed on the laminate was judged according to the following criteria. Judgment: ○ Characters can be recognized visually. Judgment: Unable to recognize characters visually.

[0067] [Abrasion resistance of the printed area] The abrasion resistance of the printed area on the outside of the packaging was evaluated using a simple abrasion resistance tester (Imoto Seisakusho Co., Ltd., IMC-1557 model). A sample was cut to 150 mm x 150 mm so that the printed area was included in the package, and this was used as the measurement sample. The package was set in the abrasion resistance tester so that the printed area on the outside of the packaging was in contact with steel wool, and the printed area was rubbed with steel wool at a back-and-forth distance of 10 cm, 50 strokes, and a speed of 15 seconds / 10 strokes. The steel wool was #0000 grit, and the weight was 1 kg. For the reference example, an arbitrary portion of the characters indicating the expiration date was measured. The printed area after being rubbed with steel wool was visually evaluated according to the following criteria. Verification: ○ The characters can be recognized visually (the characters do not disappear due to friction). Judgment: × The characters cannot be recognized visually (the characters disappear due to friction).

[0068] [Table 2A]

[0069] [Table 2B]

[0070] [Film manufacturing conditions and evaluation results] The packaging materials from Examples 1 to 4 all exhibited the excellent physical properties listed in Table 2. On the other hand, in Comparative Example 1, the heat-sealing strength was inferior because the TiO2 coated surface was heat-sealed. In Comparative Example 2, the TiO2 coated surface was used as the outer surface of the packaging, making it impossible to recognize the laser printing after wear, resulting in an undesirable laser-printed packaging. Comparative Example 3 could not be laser printed because it did not contain laser printing pigment. [Industrial applicability]

[0071] The laser-printed packaging of the present invention has a laser-printed portion that does not peel off, and can provide packaging formed by heat sealing with high productivity and cost-effectiveness.

Claims

1. A packaging body having at least one laser-printable layer that can be printed by laser irradiation, wherein the laser-printable layer has laser-printed portions and non-printed portions, the outer surface layer of the packaging body is the laser-printable layer, the laser-printable layer is a stretched film layer, and at least a part of the packaging body is heat-sealed, and the packaging body satisfies the following requirements (1) to (3). (1) The thickness of the laser printing layer is 5 μm or more and 200 μm or less. (2) The difference in color L* value between the laser-printed area and the non-printed area is 1.0 or more and 10 or less. (3) The heat-sealing strength is 5 N / 15 mm or more and 40 N / 15 mm or less.

2. The packaging according to claim 1, characterized in that the height or width of the printed size in the laser-printed portion is 0.2 mm or more and 100 mm or less.

3. The packaging according to claim 1 or 2, characterized in that it has a laser printing layer over the entire surface area of ​​the packaging.

4. The packaging according to any one of claims 1 to 3, characterized in that the laser printing layer contains one or more elements or compounds 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 claims 1 to 4, characterized in that the resin constituting the laser printing layer is polyester, polypropylene, or polyethylene.

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