JP6255845B2 - Laminated retort packaging material, packaging retort body using the same, and packaging retort laser printing body - Google Patents

Description

  The present invention relates to a laminated retort material for packaging capable of printing fine figures and characters for filling and packaging foods and drinks, pharmaceuticals, quasi-drugs, and medical instruments with a laser, a laminated retort body for packaging using the same, and The present invention relates to a retort laser printing body for packaging having a printed image by laser.

Conventionally, in addition to forming patterns such as letters, symbols, and drawings in advance on the surface of packaging containers such as cans, bottles, plastic bottles, packaging bags, and packaging materials for packaging them, for example, manufacturing A method for printing additional information such as date, manufacturer, product name, and expiration date later with ink or the like is widely known.
The packaging containers or packaging materials that make up the package are used in various applications, and depending on the purpose and use situation, etc., the selection of materials, the layered configuration or the structure can be made to meet a wide variety of requirements and demands. Changed and used as a package. For this reason, the package has a variety of laminated structures depending on the form of the package, the change of the material according to the use situation, and the like.
For such a wide variety of packaging materials, there is a need for a technique that can appropriately and accurately print additional information that requires a description for each packaging material.

  On the other hand, as a technique for printing additional information on a packaging container such as a packaging bag or a packaging material, which is a packaging body, a known printing method, an ink jet printer, laser irradiation, or the like, the surface of the packaging bag or packaging It is already known that additional information is printed between layers of a laminated structure of materials. When printing predetermined designs and fixed information on packaging containers and packaging materials, printing layers can be formed between layers by inkjet printing or general-purpose printing methods, but additional information that changes information cannot be set in advance. In some cases, it may be printed on the surface of the package, the printing may dry out, the compatibility between the package and ink, the contact of the printed surface of the package moving at high speed, etc. The problem is that printing cannot be performed appropriately and accurately, such as in the state of.

  In particular, in packaging materials having a wide variety of laminated structures, it has a laminated structure imparted with a barrier property, and can withstand retort sterilization treatment, which means that it is sterilized with heat and heat exceeding 100 ° C. under pressure, Conventional problems in printing additional information while packaging in packaging retort materials and packaging retorts that are intended to be used under harsh conditions that are required to have retort resistance Packaging retort material and packaging retort that can improve the visibility by properly and accurately, freely and clearly printing additional information on the laminated retort material and packaging retort There is a need to provide bodies and their printed bodies.

As a technique for printing with a laser beam, printing on a film by irradiating a YAG laser, a YVO ₄ laser, or the like is known. As a multilayer laminated film for packaging that can be printed with a laser, a film using a special ink that changes color by laser irradiation as an intermediate layer (coloring layer) is known (Patent Document 1).
And since such special ink is very expensive, providing this special ink layer only in the part which wants to print on a base material is performed beforehand. However, even in that case, alignment is difficult and the print position cannot be easily changed. In addition, there is a drawback that the printed line is thin and difficult to read.

Ordinary inks also change color slightly upon irradiation with a YAG or YVO ₄ laser. Therefore, it is also known to use such normal ink as an intermediate layer (coloring layer) (Patent Document 2). However, in this method, it is necessary to form a printing portion in the intermediate layer by irradiating with powerful laser light. In other words, in order to obtain sufficient visibility, the laser power is output until the intermediate layer of the laser-irradiated part is completely evaporated over the entire thickness in the depth direction (direction from one surface of the film to the other surface). Need to increase.
Accordingly, there is a problem that a hole is formed in the base film by irradiation with a powerful laser beam. In addition, there is a problem that the printing speed is slow because it is necessary to irradiate a powerful laser beam.

JP 2007-55110 A Japanese Patent Laid-Open No. 2007-217048

  The present invention is a packaging material having a wide variety of laminated structures, in particular, a laminated retort material for packaging and a retort material for packaging, which is a packaging body that provides barrier properties and is limited to a laminated structure having retort resistance. In order to solve the conventional problem of printing additional information during packaging, it is made of inexpensive materials without using special ink that changes color by laser irradiation, without using special ink that changes color by laser irradiation. It is easy to change the printing position, and it is possible to obtain a printing line having an appropriate thickness and easy to read by irradiating with a low-power laser that does not damage the base film. , Laminated retort packaging material with additional information clearly and accurately printed at any position and with improved visibility, and packaging retort using the same And to provide the door body and their print body.

  As a result of various studies, the present inventors have obtained special inks in a laminated retort material or a packaging retort body using the laminated retort material, which is a package limited to a laminated structure having barrier properties and having retort resistance. Without using, easy to obtain and highly versatile, inexpensive white ink, forming a region of only the white ink base layer that can be printed by laser light on the printed layer, by low-power laser irradiation to the region, A discoloration area is formed by spreading the carbonized ink component only on the surface of the printed image area between the base material layer and the printing layer on the viewing side, and it is arbitrarily and accurately positioned on the white ink underlayer. The present inventors have found a laminated retort material for packaging that can form a clear printed image having a moderately thick line.

  The present invention is a laminated retort material for packaging which is laminated in the order of a substrate, a pattern printing layer, a printing underlayer, a polyamide resin, and a sealant layer, and includes a gas barrier layer, the pattern printing layer and the laser printing layer, In a laminated retort material for packaging having a printed layer in which only the printing underlayer is overlapped and a region where only the printing underlayer is formed, the laser beam between the base material and the printing white ink underlayer is used. This is a laminated retort material for packaging in which only the surface of the printable undercoat layer of white ink for printing is a laser printing region for forming a discoloration region, and the above object can be achieved.

The present invention makes it possible to perform laser printing from the following points in a laminated retort material for packaging and a laminated retort body for packaging having a specific layer structure to which barrier properties are imparted and having retort resistance.
1. Laminating retort material for packaging, which is laminated in the order of base material, pattern printing layer, printing base layer, polyamide resin, sealant layer, and has a gas barrier layer, under which printing pattern layer and laser printing layer become In a packaging laminated retort material having a printing layer in which the base layer is overlapped and a printing layer in which only the printing base layer is formed, the printing base layer is a white ink layer that can be printed by laser light. This is a laminated retort material for packaging in which the region of only the underlayer is a region for laser printing.
2. It is preferable that the white ink is a laminated retort material for packaging having a laminated structure using a white ink which is a resin composition containing at least titanium oxide because laser printing is possible.
3. The gas barrier layer is a gas barrier transparent vapor deposition layer, and a laminated retort material for packaging in which a gas barrier transparent vapor deposition layer is provided on a substrate is preferable because laser printing is possible.
4). The gas barrier layer is an aluminum metal foil, and is preferably a laminated retort material for packaging positioned on the opposite side of the base material of the white ink layer which is the printing base layer, because laser printing is possible. .
5. A packaging retort body using the above-described laminated retort material for packaging is preferable because laser printing is possible.
6). What formed the retort body for packaging using the said lamination | stacking retort material for packaging is possible because laser printing is possible.
7). Discoloration region of carbonized white ink by irradiating YAG or YVO ₄ laser light to the packaging retort body from the base material layer side while filling the contents with the above-mentioned laminated retort material for packaging or retort packaging body However, a packaging retort laser printing body in which a laser printing image is formed by spreading over the boundary between the base material layer and the printing base layer is preferable as a packaging retort printing body on which additional information is laser-printed.

The packaging retort material for packaging of the present invention does not require the use of special ink for laser printing, and is a commonly used white ink that is commonly used as a base for printing printed pattern layers of packaging films. Use the laser beam to form a printing base layer that is formed as a white ink layer that can be printed on the entire area of the laminated retort material for packaging, and overlay the necessary pattern printing layer on the substrate side of the printing base layer. By the laminated structure made, it is a laminated retort material for packaging in which the printing base layer that can be printed by laser light is formed in the entire area, so that the area of only the printing base layer can be provided at an arbitrary position, Moreover, a laser printing area can be formed by irradiating the area with laser.
The present invention can be used as a base layer for forming a print layer for laser printing additional information, as a base layer for a pattern printing layer, white ink that is normally used as a base for printing a package, A laminated retort material for packaging can be produced from an inexpensive material.

In addition, by irradiating the laminated retort material for packaging of the present invention with a YAG or YVO ₄ laser from the substrate layer side, the ink component forming the print layer is carbonized by laser irradiation, and the substrate and the print layer Excellent output from the substrate layer side due to the low output because it spreads to the boundary, that is, it is not necessary to increase the laser output until the printing layer is completely evaporated over the entire thickness, and contrast with the white ink base as the base A laser-printed image can be clearly formed.
Further, in the printing body of the present invention, the laser-printed image is applied not inside the film surface but inside, that is, between the base material layer and the printing layer. Therefore, since this image has excellent wear resistance, it is possible to effectively prevent disappearance due to rubbing or the like, and to prevent change of the additional information.

From these advantages, according to the laminated retort material for packaging according to the present invention and the packaging retort body using the same, additional information can be formed in a region other than the heat-sealed portion of the retort body. In addition, it is easier to read variable information such as the date of manufacture, manufacturer, product name, expiration date, production location, etc. compared to printing by a conventional inkjet printer, and a large amount of information can be printed as a laser print image.

The ink is brought into contact with the surface of the packaging retort material when the printing underlayer of the white ink at least the inner layer other than the layer in contact with the contents of the packaging retort body becomes a printable layer that can be printed by laser light irradiation. It is possible to print without any problems, and it is possible to obtain a product having excellent hygiene without dissolving the ink printed by the oil and fat derived from the contents of the packaging laminated retort material.
Moreover, in the manufacturing process of the laminated retort material for packaging, only the same printing process as that of the ordinary printing process is performed, and it is not necessary to provide a further layer for laser printing, and the manufacturing process can be simplified.

It is a schematic sectional drawing which shows the example about the layer structure of the lamination | stacking retort material for packaging of this invention. It is a schematic sectional drawing which shows another example about the layer structure of the lamination | stacking retort material for packaging of this invention. FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of a packaging retort printing body using a laminated retort material for packaging according to the present invention shown in FIG. FIG.

  The laminated retort material for packaging according to the present invention, the packaging retort body using the same, and the layer structure of the printed body will be exemplified and described in detail below with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of the layer structure of the laminated retort material for packaging according to the present invention.
As shown in FIG. 1, the laminated retort material for packaging according to the present invention is laminated in the order of a base material, a pattern printing layer, and a printing underlayer, and a sealant layer on the innermost layer of the laminated structure including a gas barrier layer. A laminated retort material for packaging having a printing layer in which an area in which a pattern printing layer and a printing underlayer serving as a laser printing layer overlap each other and a printing layer in which only the printing underlayer is formed are formed In the material, the base layer for printing is basically composed of a laminated retort material for packaging, which is a white ink layer that can be printed by laser light.

  In another embodiment, as shown in FIG. 2, if the pattern printing layer is a pattern printing layer made of the same or different ink and having excellent adhesion to the base material layer, two or more layers are used. A stacked structure may be used.

As shown in FIG. 3, the printed body of the present invention is produced by irradiating the laminated retort material for packaging of the present invention with a YAG or YVO ₄ laser from the substrate layer side, On the surface of the base layer, there is a printed part in which the carbonized ink component spreads.

(Base material layer)
In the present invention, the base material layer is a resin film according to the purpose of use, application, etc., and when the printing layer is laminated, the lamination strength with the printing underlayer is the lamination strength with the pattern printing layer. Any resin film that is somewhat smaller can be used.
Specifically, it becomes a basic material, and further, after printing, it constitutes a surface protective layer and can be seen through a laser-printed image, etc., so it is excellent in mechanical, physical, chemical, etc. A resin film having strength, excellent puncture resistance, and the like, and excellent heat resistance, moisture resistance, transparency, and the like can be used.

In the present invention, examples of such resin films include various resin films such as polyolefin resins such as polyethylene resins and polypropylene resins, cyclic polyolefin resins, fluororesins, polystyrene resins, polyester resins, polyamide resins, and cellulose resins. You can choose.
In addition, at the time of film formation using one or more of the above-mentioned various resins, for example, film processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slipperiness, release properties, etc. Various plastic compounding agents and additives can be added for the purpose of improving and modifying moldability, flame retardancy, antibacterial properties, electrical properties, strength, laminate strength, etc. Can be arbitrarily added from a very small amount to several tens of percent depending on the purpose.
In the above, as a general additive, for example, a lubricant, a crosslinking agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a filler, a reinforcing agent, an antistatic agent, a pigment, and the like can be used. Furthermore, a modifying resin or the like can also be used.

In order to adjust the laminate strength and adhesion between the printing base layer of the white ink and the base material, any surface can be subjected to a desired surface treatment before lamination as necessary. As the surface treatment, for example, pretreatment such as corona discharge treatment, ozone treatment, low temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, oxidation treatment using chemicals or the like can be performed. .
Moreover, you may provide a primer coating agent layer, an undercoat agent layer, an anchor coating agent layer etc. between a printing foundation layer and a base material layer, for example.

As the resin film, any of an unstretched film or a stretched film stretched in a uniaxial direction or a biaxial direction can be used.
In the present invention, as the various resin films, for example, one or more of the various resins described above are used, and film forming methods such as an extrusion method, a cast molding method, a T-die method, a cutting method, and an inflation method are used. Using various methods, the above-mentioned various resins can be formed into a single film, or two or more types of resins can be used and mixed before forming into a film to form a film of various resins. Further, for example, any of a stretched film stretched in a uniaxial direction or a biaxial direction using a tenter method, a tubular method, or the like can be used.

In the present invention, the thickness of the resin film may be a thickness that can be kept to the minimum necessary for strength, puncture resistance, and the like. On the other hand, if it is too thin, the strength, puncture resistance and the like are reduced, which is not preferable.
In the present invention, for the reasons described above, 10 to 100 μm, preferably 10 to 50 μm is desirable.

  In the present invention, as the resin film for forming the base material layer, polyethylene terephthalate (PET) and a PET base material on which a transparent vapor deposition layer is formed can be particularly preferably used. The polyethylene terephthalate film is excellent in terms of stability, processability, cost, heat resistance, chemical resistance, etc., particularly in applications as packaging materials, and is a printing ink suitably used as a printing layer described later. When laminating, a preferable laminate strength with the printed layer can be obtained. When using PET having a transparent vapor deposition layer as a substrate, it is not necessary to provide a gas barrier layer separately, but a barrier layer may be laminated as necessary.

(Print layer)
In the present invention, the printing layer is composed of a pattern printing layer and a printing base layer, and is a layer provided by laminating a commonly used ink on a base material layer by printing or coating.
In the present invention, the picture print layer is formed by printing a desired print picture such as a character, a figure, a symbol, a picture, or a pattern on the base material layer using a normal printing method.
On the other hand, the printing underlayer of the present invention uses a white ink that can be printed by laser light, and the metal oxide constituting the white ink includes titanium oxide, magnesium oxide, zinc oxide, aluminum oxide, silicon oxide. In this sense, the ink is used as a general-purpose printing foundation layer. Especially in this invention, what contains a titanium oxide as a white pigment in the white ink used as printing base ink of a packaging film is used suitably.

  In this invention, content of the metal oxide in white ink can be used in 5 to 90 weight%, and it is preferable to contain 20 to 50 weight%. When the content of the metal oxide is less than 5% by weight, it becomes difficult to form a sufficient color change region between the base material and the ink layer by laser light irradiation, and it becomes difficult to obtain a clear print. When the content is 90% by weight or more, the content of the metal oxide of the white ink is excessively large and sufficient adhesion to the substrate cannot be imparted, and the ink underlayer becomes brittle.

The binder resin constituting the ink is conventionally known, and when laminated on the base material layer, the laminate strength with the base material layer is relatively small, 1.5 to 4.5 N / 15 mm. Any binder resin can be used.
Specifically, urethane resin, polyester resin, acrylic resin, cellulosic resin, and the like can be given. These resins are used alone or in combination of two or more. In particular, a urethane resin is preferably used as the binder resin in the white ink used as the printing base layer. When the urethane resin is laminated on the stretched polyamide film suitably used as the above-mentioned base material layer, the urethane resin gives a preferable laminate strength with the base material layer, and is a component of white ink that is baked in printing with a laser beam. Is appropriately spread between the base layer and the base material layer, and has a laminate strength suitable for the base material layer to be recognized as characters.

  In the present invention, the content of the resin component in the white ink is preferably in the range of 5 to 50% by weight. If it is less than 5% by weight, sufficient adhesion to the substrate is lowered, and the substrate and the ink layer are easily peeled off by irradiation with laser light, making it difficult to obtain a clear print. When it is 50% by weight or more, it becomes difficult to form a color change region, and the content of the metal oxide in the white ink is small, and it becomes difficult to form a sufficient color change region by laser light irradiation.

  As the printing base ink of the present invention, any white ink conventionally used as a printing base can be suitably used. A printing layer can be formed by diluting a white ink with a conventional solvent as necessary, and printing or coating on the base material layer. When white ink contains a large amount of metal oxide, the film is easily damaged by laser irradiation. Conversely, if the amount of metal oxide is small, the printed image tends to be unclear.

In order to adjust the laminate strength of the base material layer and the printing layer to a desired range, an optional additive may be added to the ink as necessary. Examples of this include addition of a lubricant, an antiblocking agent, a filler, a curing agent, and the like. In addition, various additives such as pigment dispersants, antifoaming agents, leveling agents, waxes, silane coupling agents, preservatives, antioxidants, UV absorbers, rust inhibitors, plasticizers, flame retardants, color developers, etc. It can also be added. These additives are used particularly for the purpose of improving printability, printing effect, and the like, and the type and amount used can be appropriately selected depending on the printing method, printing substrate, and printing conditions.
Further, the laminate strength may be adjusted by performing a surface treatment such as corona treatment on the laminated surface of the base material layer, or by laminating a printing layer on an untreated surface.

In the present invention, the printing layer may have a structure in which two or more printing layers made of the same or different inks are laminated. Here, the printing base ink that forms the printed layer on the side in contact with the base material layer is such that the laminate strength with the base material layer is the weakest in the printed layer constituting the laminated retort material for packaging, For example, the type, content, lamination method, and the like of the binder resin are selected so that the range is 1.5 to 4.5 N / 15 mm.
In addition, the ink component forming the printed layer on the side in contact with the adhesive layer to which the aluminum foil is bonded is, for example, 5.0 N / 15 mm or more so that the laminate strength between the adhesive layer and the adhesive layer becomes stronger. Adjust as well. With this configuration, a color change region of the laser print image can be reliably formed at the boundary between the base material layer and the print layer at the time of laser irradiation, and delamination between the print layer and the aluminum foil barrier layer can be prevented.

The total thickness of the printed layer, the coating amount of the ink, it is preferable 1.5~4.5g / m ^2, more preferably from 2.7~3.6g / m ² The coating amount after drying. If the printing layer is thicker than this, the film is easily damaged by laser irradiation. Conversely, if it is thinner than this, the printed image tends to be unclear.
In addition, in order to obtain the laminate strength defined in the present invention between the base material layer and the printing layer (the pattern printing layer and the printing ground layer), the pattern printing layer or the printing ground layer can be multilayered. However, it is possible to more reliably obtain the strength specified by the one-layer printing layer.

In addition to printing by a known method such as gravure roll coating, reverse roll coating method, knife coating method, kiss coating method, etc., the method of laminating the printing layer can use methods such as inkjet, immersion, spin coating, In the present invention, a method of laminating by printing is preferable. If a printing machine capable of winding a film after printing is used in a printing system in which white ink is present, any of gravure printing, offset printing, letterpress printing, and flexographic printing may be used. In particular, the production process can be simplified by solid printing on the entire surface or part of the printing substrate. The gravure can be easily applied in large quantities, and solid printing can be performed on the entire surface or part of the printing base, thereby improving the concealment and simplifying the manufacturing process. The printing method is suitable.
In the present invention, in order to obtain a laminated retort material for packaging that is clear and does not cause uneven printing by laser light, the coating amount of the ink is 1.5 to 4.5 g / m ² as the coating amount after drying. Is suitable.

(Gas barrier layer)
In the present invention, a metal foil or a metal oxide vapor deposition layer can be used as a barrier layer for improving the retort property. As a means for imparting the function of the barrier layer, a base film with a transparent vapor deposition layer in which a transparent vapor deposition layer of an inorganic oxide is formed on the base film layer can also be used. Further, a transparent vapor deposition layer of an inorganic oxide is formed on a laminated constitution layer different from the substrate of the laminated retort material for packaging to provide a barrier property, or a resin film having a transparent vapor deposition layer is formed between the substrate and the sealant layer. It can also be provided by laminating and arranging.
Moreover, when using metal foil, such as aluminum foil, as a barrier layer, metal foil can provide barrier property by arrange | positioning on the opposite side to the base material of a printing foundation layer.
As the barrier layer, a barrier resin coating film having barrier properties such as water vapor and oxygen, such as vinylidene chloride resin, polyvinyl alcohol resin, ethylene vinyl alcohol copolymer resin, and saponified ethylene-vinyl acetate copolymer is used. You can also
As the inorganic oxide vapor-deposited film, a transparent thin film obtained by making a metal oxide amorphous can be used. For example, silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), boron (B), titanium (Ti), zirconium (Zr), yttrium (Y A transparent vapor deposition film obtained by making a metal oxide such as) amorphous (amorphous) can be used.
And as suitable for packaging materials, etc., silicon (Si), aluminum (Al)
A thin film obtained by making an oxide of a metal such as amorphous into an amorphous state can be given.

The vapor deposition layer constituting the gas barrier layer of the present invention is, for example, a physical vapor deposition method (Physical Vapor Deposition method, PVD method) such as a vacuum vapor deposition method, a sputtering method, an ion plating method, an ion cluster beam method, or the like. It can be formed using a chemical vapor deposition method (Chemical Vapor Deposition method, CVD method) such as a plasma chemical vapor deposition method, a thermal chemical vapor deposition method, or a photochemical vapor deposition method.
In the present invention, the inorganic oxide vapor deposition film is specifically a vacuum vapor deposition method in which a metal oxide is used as a raw material, and this is heated and vapor deposited on a resin film or sheet, or a metal as a raw material. Or oxidation reaction vapor deposition method that uses metal oxide, oxidizes by introducing oxygen and deposits on resin film or sheet, plasma-assisted oxidation reaction vapor deposition method that promotes oxidation reaction with plasma, etc. Can be used to form an amorphous thin film of inorganic oxide. In the above, the heating method of the vapor deposition material can be performed by, for example, a resistance heating method, a high frequency induction heating method, an electron beam heating method (EB), or the like.

  In the present invention, the thickness of the metal or metal oxide thin film layer varies depending on the type of metal or metal oxide used, but is, for example, in the range of 50 to 3000 mm, preferably in the range of 100 to 1000 mm. It is desirable to select and form arbitrarily. In the present invention, the thin film layer of metal or metal oxide may be not only one layer but also a laminated body in which two or more layers are laminated, and the metal or metal oxide to be used Can be used as a single type or a mixture of two or more types to form a thin film layer made of different materials.

(Polyamide resin layer)
As the polyamide resin film constituting the laminated retort material for packaging according to the present invention, any polyamide resin film that can hold an amorphous thin film of aluminum oxide can be used. Various polyamide-based resin films or sheets such as nylon 46, nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, and others can be used. These polyamide resin films or sheets may be uniaxially or biaxially stretched, and the thickness is about 10 to 200 μm, preferably about 10 to 50 μm. Further, the polyamide resin film or sheet may be subjected to a surface smoothing treatment by coating the surface with an anchor coating agent or the like, if necessary.

  A method for producing a laminated material using a polyamide-based resin material will be described. Examples of such a method include a method for laminating a normal packaging material, for example, a wet lamination method, a dry lamination method, a solventless dry lamination. , Extrusion extrusion method, T-die extrusion molding method, co-extrusion lamination method, inflation method, co-extrusion inflation method, etc.

  In the present invention, pre-treatment such as corona treatment and ozone treatment can be applied to the film, for example, if necessary, when performing the above lamination, and for example, isocyanate (urethane), polyethyleneimine Known anchor coating agents such as polyurethane, polybutadiene, and organic titanium, or adhesives for laminating such as polyurethane, polyacryl, polyester, epoxy, polyvinyl acetate, cellulose, etc. Pre-treatment, anchor coating agent, adhesive and the like can be used.

(Sealant layer)
In the present invention, the sealant layer is provided in the innermost layer of the laminated retort material for packaging, and is a layer made of a conventional thermoplastic resin or a layer made of a film of the resin as the sealant layer.
The sealant layer is a heat-sealable resin used for the heat-sealable resin layer, and specifically, a resin film or sheet that can be melted by heat and fused to each other can be used. Low density polyethylene, medium density polyethylene, high density polyethylene, linear (linear) low density polyethylene polymerized using a metallocene catalyst, ethylene-α / olefin copolymer polymerized using a metallocene catalyst, Polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene Copolymer, methylpentene polymer, polybutene polymer, polyethylene or polymer Polyolefin resins such as pyrene modified with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, polyvinyl acetate resins, poly (meta ) Acrylic resins, polyvinyl chloride resins, and other resins can be used alone or in admixture of two or more.
Among the heat-sealable resins that make up the above sealant layer, those in which linear (linear) low-density polyethylene is polymerized using a single site catalyst such as a metallocene catalyst have a narrow molecular weight distribution and are copolymerized. Since the ratio is also stable, it has excellent heat resistance, content resistance, stress cracking resistance, low-temperature heat sealability, and hot sealability, and the sealant layer of the laminated retort for packaging of the present invention Can be suitably used.

  In addition to the above-mentioned linear (linear) low density polyethylene, the heat seal resin layer includes CPP (unstretched polypropylene), LDPE, depending on the contents to be filled, the heat treatment after filling, the distribution conditions, and the like. Select an appropriate film or extruded coating layer such as ethylene / α-olefin copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / acrylic acid ester copolymer, ionomer, and polyester resin. Can be used.

In the use as a packaging material, when it becomes the innermost layer in contact with the contents, polyolefin resins such as polyethylene and polypropylene are preferably used. In particular, in the retort material of the present invention, unstretched polypropylene is used as the sealant layer.

  The method for laminating the sealant layer is not particularly limited, but the thermoplastic resin forming the sealant layer can be laminated on the polyamide resin by a dry laminate method or a sandwich laminate method.

As an adhesive for dry lamination, urethane adhesive, polyester polyurethane adhesive, polyester adhesive, polyether adhesive, vinyl adhesive, acrylic adhesive, epoxy adhesive, and the like can be used. . Further, any thermoplastic resin can be used as the adhesive resin for sandwich lamination.
In the present invention, the sealant layer can be formed by using the heat sealable resin as described above and extruding and laminating by an extrusion laminating method or the like.
In the present invention, the thickness of the sealant layer can be appropriately set according to the content filled in the laminated retort material for packaging, but is preferably about 20 to 200 μm, more preferably 50 to 100 μm.

Moreover, you may provide a primer coat layer, an undercoat layer, an anchor coat layer etc. between the polyamide-type resin layer and a sealant layer, for example.
As the anchor coat layer constituting the laminated retort material for packaging of the present invention, either a solvent type or an aqueous type can be used.
Therefore, (chlorinated) polypropylene, modified polyolefin, ethyl vinyl alcohol, polyethylene imine, polybutadiene, polyurethane, polyester polyurethane emulsion, polyvinyl chloride emulsion, urethane acrylic emulsion, silicon acrylic emulsion, vinyl acetate acrylic emulsion , Acrylic emulsion, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, chloroprene latex, polybutadiene latex rubber latex, polyacrylate latex, polyacrylate Vinylidene chloride latex, polybutadiene latex, or carboxyl modification of these latexes And water-soluble substances such as polyvinyl alcohol, water-soluble ethylene-vinyl acetate copolymer, polyethylene oxide, aqueous acrylic resin, aqueous apoxy resin, aqueous cellulose derivative, aqueous polyester and aqueous lignin derivative, etc. An emulsion or dispersion anchor coat agent is used. For example, when the outermost layer is a polyethylene-based melt-extruded resin layer, a polyethylene-based or modified polyolefin-based emulsion or dispersion is preferable in consideration of adhesiveness to the substrate.

(Lamination strength)
In the laminated retort material for packaging of the present invention, when the base material layer is made of a PET film and a urethane resin is used as the binder resin in the ink, an adhesive that adheres an aluminum foil or a polyamide resin layer As a binder resin for forming a layer, a suitable laminating strength relationship between the base material layer or an adhesive layer for bonding an aluminum foil or a polyamide-based resin layer and the base layer for printing, that is, a laminated retort material for packaging is a retort. The strength of the laminate that forms the body increases, so that the adhesion of the retort material does not peel off when printing with laser light, and a clear print image can be obtained by laser irradiation between the base material layer and the print layer. It is necessary to set the strength so that it can protrude in a convex shape.
In any case, a combination of resin types and a lamination method so that the laminate strength between the printing foundation layer and the adhesive layer to which the aluminum foil or polyamide resin layer is bonded is 5.0 N / 15 mm or more. Select the type of adhesive, surface treatment method, etc.
In the present invention, the laminate strength between the substrate layer and the printed layer is 1.5 to 4.5 N / 15 mm, more preferably 2.0 to 2.8 N / 15 mm, and the printed layer and the sealant. The laminate strength between the layers needs to be larger than the laminate strength between the base material layer and the printing underlayer, and the strength is 5.0 N / 15 mm or more, more preferably 6.0 N / 15 mm or more. .
Laser printing is optimally performed by the layer structure having such a laminate strength. If the laminate strength between the base material layer and the printed layer is a weak laminate strength of less than 1.5 N / 15 mm, delamination is caused outside the laser irradiation part, and if the laminate strength exceeds 4.5 N / 15 mm, the base material / The color change area between printing layers is small, and the printed image becomes unclear. Further, when the laminate strength between the printing layer and the sealant layer is smaller than 5.0 N / 15 mm, the reliable formation of the color changing region between the substrate and the printing layer is impaired. In addition, delamination that is undesirable as a packaging material is caused.

In the present invention, the laminate strength is a value measured by a T-type peel adhesion strength test in which the moving speed is 50 mm / min, the width of the measurement sample is 15 mm, and other conditions are performed in accordance with JIS K6854.
In order to achieve the above laminate strength, by the combination of the type of resin film that forms the base layer, the type of binder resin and white ink pigment in the ink that forms the printed layer, and the type of resin that forms the sealant layer, It is preferable to find a combination that provides the laminate strength relationship. However, in order to intentionally reduce the laminate strength, a printing layer may be laminated on a surface not subjected to corona treatment, or a material that prevents adhesion to the ink component, such as an anti-blocking agent, may be added.

(Printing with laser light)
In the present invention, printing is performed using a YAG (yttrium (Y), aluminum (A), garnet (G)) laser beam (wavelength = 1.064 μm) or a YVO ₄ (yttrium vanadate) laser beam (wavelength = 1.064 μm). It is preferable to carry out using. These lasers have the property of transmitting through a transparent body, and by utilizing this property, the generation of smoke and the like during printing can be suppressed, and the color density and the effect on the film can be adjusted. . As a result, it is possible to form a very clear laser-printed image having no holes or the like even when a laser-printed image is formed.
By irradiating these lasers from the base material layer side of the laminated retort material for packaging, the transparent vapor deposition film provided on the base material in the laminated retort material for packaging can be used as a base layer for printing white ink even if the laser light is low in output. The ink component of the printing layer is gasified and carbonized without disturbing the formation of the printed image and minimizing damage to the film, and between the base layer and the printing layer. In this case, a void can be formed on the surface of the printing base layer, and a laser printed image can be efficiently formed on the surface of the printing base layer. And the thing excellent in the visibility from the base-material layer side is obtained by forming a laser-printed image in the surface of the printing base layer of white ink.

In the present invention, pulse conditions for performing such printing are, for example, an average output of 0.8 to 5 W, more preferably 2 to 4 W, and a Q switch frequency of 10 to 10 with a YVO ₄ laser machine (MD-V9600 manufactured by Keyence). Pulse conditions of 30 KHz and a scan speed of 300 to 4000 mm / s, more preferably 1500 to 3000 mm / s are used. By printing under these conditions, high-speed printing is possible without making holes in the packaging multilayer laminated film, and a clear printed image can be obtained.

(Printed body with laser light)
In the printing process on the laminated retort material for packaging according to the present invention, even if the average output of the laser is set low or the scan speed is set high, a clear print image, for example, a thick and clear character is printed. be able to.
In the printed body of the present invention, the diameter of the discoloration region formed between the base material layer and the printed layer by laser spot irradiation is desirably 40 μm to 1 mm, more preferably 400 to 700 μm. A carbonized ink component spreads in this discoloration region, and a clear printed image can be obtained by using the white ink of the printing base layer as a background. If the diameter of the discoloration area is smaller than this, the printed image is lost or the line width is narrowed, and visibility is lost. Conversely, if it is larger than this, it is not preferable because the image is crushed.
In the present invention, the laser printed image includes, but is not limited to, letters, numbers, symbols, designs, and the like.

The packaging retort material for packaging and the packaging retort printing material obtained by printing on the packaging retort material of the present invention can be suitably applied to the packaging material for retort as a printed material having a laminated structure having the retort resistance of the present invention. it can.
In the laminated retort material for packaging according to the present invention, the printing layer is printed on a region consisting only of white ink that functions as a printing base layer that can be printed by laser light, and the printing layer is not printed by laser light. The area where the pattern printing layer provided with the desired color printing layer and the printing base part are superposed has adhesion with the base material layer even in an atmosphere under wet heat, has a high lamination strength, and is used as a laminated retort material for packaging. In combination with the fact that no peeling occurs, a clear print can be reliably obtained in the print area.

(Retort body for packaging)
A packaging retort body using the above-described laminated retort material for packaging will be described. A bag-like container body made of a packaging retort body uses a laminated material made of the packaging laminated retort material,
Fold this laminate into two, superimpose the heat-sealable resin layers facing each other, heat-seal the end to form a cylindrical package, and then seal the bottom to fill the contents And a package can be manufactured by sealing a top part further.
As the bag making method, the laminated material as described above is folded or overlapped so that the inner layer faces each other, and the peripheral end thereof is, for example, a side seal type, a two-side seal type, a three-side seal. Various types of heat seals such as molds, four-sided seals, envelope stickers, pillow seals, pleated seals, flat bottom seals, square bottom seals, gussets, etc. A laminated retort body for packaging in the form can be produced. In the above, as a heat sealing method, for example, a known method such as a bar seal, a rotary roll seal, a belt seal, an impulse seal, a high frequency seal, and an ultrasonic seal can be used.

  EXAMPLES The present invention will be specifically described below with reference to examples, but these do not limit the present invention.

[Examples 1 to 3]
A pattern printing layer of color ink was applied to one surface of a 12 μm thick PET film by a gravure roll coating method using color ink. In addition, the composition of the titanium oxide and resin of the ink composition is urethane of 45% by weight of titanium oxide, 15% by weight of resin, 20% by weight of titanium oxide, 10% by weight of resin, 30% by weight of titanium oxide, and 5% by weight of resin. A white ink underprint layer was coated on the entire surface by a gravure roll coating method using each of the system white inks to provide a gravure print layer. Next, an aluminum foil having a thickness of 9 μm is formed on the printed layer by a dry lamination method using a two-component curable polyester adhesive (manufactured by Toyo Morton Co., Ltd .: main agent TM556 / curing agent CAT5). Thickness as a biaxially stretched polyamide (nylon) film with a thickness of 15 μm and a sealant layer using a liquid curing type polyester polyurethane adhesive (adlock manufactured by Rock Paint Co., Ltd .: main agent RU004 / curing agent H1) Each 50 μm polypropylene resin was sequentially laminated. Thereby, PET film of the present invention / pattern color ink printing layer / white ink base printing layer / adhesive layer / AL (barrier layer) / adhesive layer / biaxially stretched polyamide film / adhesive layer / unstretched polypropylene sealant layer Three types of laminated retort materials for packaging having a layer structure of:
In the laminated retort material for packaging, the laminate strength between the base material layer and the printed layer is 2.1 N / 15 mm, and the laminate strength between the printed layer and the sealant layer is 6.0 N / 15 mm. It was.

[Examples 4 to 6]
On the vapor deposition layer side of a polyethylene terephthalate film (base material layer) provided with a transparent aluminum oxide vapor deposition layer by a PVD method having a thickness of 12 μm, the same as in Example 1 by the gravure roll coating method. Using a color ink and a white ink, a pattern printing layer and a white ink base printing layer were sequentially applied to provide a gravure printing layer. Next, a biaxially stretched polyamide (nylon) having a thickness of 15 μm is formed on the printed layer by a dry lamination method using a two-component curable polyester adhesive (Adlock manufactured by Rock Paint Co., Ltd .: main agent RU77T / curing agent H7). ) A polypropylene resin having a thickness of 50 μm was sequentially laminated as a film and a sealant layer. Thereby, three types of laminated retorts for packaging having the layer structure of the PET film / picture color ink printing layer / white ink underlayer printing layer / adhesive layer / biaxially stretched polyamide film / adhesive layer / polypropylene sealant layer of the present invention. A laminated retort material for packaging of the present invention was produced in the same manner as in Example 1 except that the material was obtained.
In the laminated retort material for packaging, the laminate strength between the base material layer and the printed layer is 2.3 N / 15 mm, and the laminate strength between the printed layer and the sealant layer is 6.0 N / 15 mm. It was.

[Laser printing method]
The resulting packaging laminate retort material in Example 1-6, under the following conditions, irradiation with YVO ₄ laser light from the substrate layer side to obtain a print body to form a laser printed image.
Laser irradiation conditions YVO ₄ laser machine (Keyence Co., Ltd. MD-V9600 average output 3.0 W, Q switch frequency 10 KHz, scan speed 500 mm / s.

(Evaluation method)
Hereinafter, for each laminated retort material for packaging shown in the examples, the expiration date is printed on the white ink underlayer by actually irradiating the laser beam, and the clarity of the printed characters and the thickness of the printed characters are maintained. In addition, the printed characters such as the color density were comprehensively judged, and the visibility was evaluated.

[Evaluation]
In Examples 1 to 6, the laser printed images obtained under the above laser irradiation conditions were evaluated for visibility and the appearance of the laminated retort packaging material after laser irradiation. The laminated retort for packaging according to the present invention. The material is a white ink component composition, and even when printed with low irradiation energy (3.0 W), the print density due to discoloration is high, and the discoloration area does not disappear even if rubbed, and the color change area is thick and clear and visible. The laser printing was good, and the appearance of the laminated retort material for packaging was neither deformed nor altered by the laser beam.

1. Base material 2. 2. Transparent vapor deposition layer Print layer 3a. Pattern printing layer 3b. 3. Print base layer Metal foil.
5. 5. Polyamide layer Sealant layer Print section

Claims (6)

The resin film substrate, a picture printed layer, printing underlayer, polyamide resin, are laminated in the order of the sealant layer, and a laminated packaging retort material comprising a gas barrier layer, a laser as a picture-printed layer and the laser printing layer In a laminated retort material for packaging having a printing layer in which a white ink base layer for printing using a base white ink that can be printed by light is overlapped and a region of only a white ink base layer for printing,
When the resin film substrate and the printing layer are laminated, the lamination strength with the white ink undercoat layer for printing is smaller than the lamination strength with the pattern printing layer, and printing between the substrate and the printing layer on the viewing side A laminated retort material for packaging that forms a print discoloration area by laser by spreading the ink component carbonized by laser only on the surface of the area of only the white ink undercoat layer .   The laminated retort material for packaging according to claim 1, wherein the white ink is a resin composition containing at least titanium oxide.   The laminated retort material for packaging according to claim 1 or 2, wherein the gas barrier layer is a gas barrier transparent vapor deposition layer, and is provided with a gas barrier transparent vapor deposition layer on a substrate.   The laminated retort material for packaging according to any one of claims 1 to 3, wherein the gas barrier layer is an aluminum foil and is located on the side opposite to the substrate of the printing base layer.   The packaging retort body using the lamination | stacking retort material for packaging of any one of Claims 1-4. The packaging retort body according to packaging laminate retort material or claim 5 according to any one of claims 1 to 4, by irradiating YAG or YVO ₄ laser beam from the substrate side, and carbonized color transition range of the white ink is spread on the boundary of the group Zai及 beauty the printing white ink underlying layer, packaging retort laser printing having a laser printed image.

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