JP5382300B2 - Retort packaging - Google Patents

Description

  The present invention relates to a retort package that has excellent printability on a bag with laser light and has retort suitability.

  Conventionally, as a package for retort, for example, a film-like laminate of PET (or OPP) / ON / Al foil / CPP (or LLDPE) is generally used from the surface side. Here, the surface layer is a biaxially stretched polyethylene terephthalate (PET) film or a biaxially stretched polypropylene (OPP) film, the barrier layer is an aluminum foil (Al foil), the inner surface heat seal layer is unstretched polypropylene (CPP) or Linear low density polyethylene (LLDPE) and biaxially stretched nylon (ON) for improving impact resistance and self-supporting property (standing up) are used as an intermediate support layer.

  In such a package for retort, for example, expiry information on the contents, such as expiry date, expiry date, filling date, etc., is printed on the surface of the packaging bag. Because it is information calculated from the time, it is printed on the surface of the packaging bag before and after filling the contents. And there are printing methods such as hot stamp, ink jet, thermal printing, etc., but there are problems of printing speed, accuracy, and dropout during retort.

On the other hand, laser printing is generally known for printing on PET bottles, electronic components, and the like (Reference Document 1). In the retort packaging as described above, a printing layer is often provided on the back side of the surface layer, but even when trying to print by laser irradiation from the surface layer side, it is difficult to adjust the laser output and the energy is low. Only the surface layer such as the PET layer is perforated, and the display is difficult to read against the background of the ink layer. On the other hand, even if it is attempted to fly to the ink layer by increasing the energy, it is perforated to the ON layer depending on the location. Etc. are exposed. In such a case, there is a problem that the aluminum ground is corroded by hot water during retorting and the barrier property is impaired, and there is a high risk of pinholes.
JP-A-2005-319501

  In the present invention, when forming a deadline information printing portion related to contents in a retort pouch by laser irradiation, the half cut range can be accommodated without affecting the intermediate support layer, and printing with excellent printing visibility can be achieved. At the same time, an object of the present invention is to provide a retort package capable of preventing deterioration of physical properties of the laser irradiation part even during retort operation.

The retort packaging body of the present invention includes at least a surface layer, a laser reflective ink layer, an intermediate support layer, a barrier layer, and a heat seal layer, which are laminated in this order, and a printed layer and a laser absorbent between the surface layer and the laser reflective ink layer. A film-like laminate having layers is overlapped with the surface layer side as the outside and the heat seal layer side as the contents side, the peripheral edge is heat sealed, and the expiration date information about the contents is printed on the surface layer side In the packaging bag, the film-like laminate in the deadline information printing part was half-cut from the surface layer side to the laser reflective ink layer in the cross-sectional direction by laser irradiation from the surface layer side, and the deadline information was printed. It is characterized by that.

  Said laser reflection ink layer is a metallic ink layer containing 3-10 mass% of metal powder.

  The metal powder is a leafing type aluminum powder.

  A printing layer is provided between the surface layer and the laser reflecting ink layer.

  Said printing layer contains a laser absorber, It is characterized by the above-mentioned.

  Each of the laser reflective ink layer, the intermediate support layer, the barrier layer, and the heat seal layer is laminated using a laminating adhesive.

  The retort package of the present invention is capable of reflecting the laser irradiation by the laser reflecting ink layer when forming the time limit information printing portion relating to the contents in the retort pouch with a laser. It is possible to prevent deterioration of physical properties of a barrier layer such as an Al foil in a laser irradiation portion during retorting without being damaged.

  The retort package of the present invention will be described with reference to the drawings. FIG. 1 is a front view showing an example of the retort package of the present invention, and FIG. 2 is a cross-sectional view showing the layer structure of the film-like laminate in the retort package of the present invention. Moreover, FIG. 3 is a schematic diagram for demonstrating the cross-sectional state in the time limit information printing part 7 regarding the contents of the retort packaging body of this invention.

  In the figure, 1 (1a, 1b) is a film-like laminate, 2 is a side seal portion, 3 is an upper seal portion, 4 is a bottom seal portion, 5 is a notch, 6 is a cut-out portion, and 7 is time limit information about contents. Printing part, 10 is a retort package, 11 is a surface layer, 12 is a printing layer, 13 is a laser reflective ink layer, 14 is an intermediate support layer, 15 is a barrier layer, 16 is a heat seal layer, 17 is an adhesive layer, 18 Indicates a half-cut portion.

  First, the retort packaging body 10 shown in FIG. 1 has two film-like laminates 1a and 1b overlapped with the surface layer as the outside and the heat seal layer as the inside, and the three sides are heat-sealed 2, 2, and 4. Therefore, after the expiration date printing section 7 relating to the contents is formed before and after the contents are stored, the upper seal 3 is provided. In addition, the package 10 is provided with notches 5 and 5 for opening at the side seal portions 2 and 2 in the vicinity of the upper seal 3 and a cutout portion 6 starting from the notches 5 and 5. Yes.

Next, the film-shaped laminated body 1 (1a, 1b) in this invention shown by FIG. 2, FIG. 3 is demonstrated.
Examples of the surface layer 11 in the film-like laminate include polyester films such as polyethylene terephthalate film (PET) and polybutylene terephthalate film, and polyamide films such as polypropylene film (PP), 6-nylon film, and 6,6-nylon film. Is done. In general, those having improved heat resistance and impact resistance by performing biaxial stretching are used. The thickness of the surface layer (film) is 5 μm to 20 μm.

  A printed layer 12 is provided on the front surface (not shown) and / or the back surface of the surface layer 11. As the ink to be used, a heat resistant water gravure ink having a normal two-component curable urethane resin as a main color change material and a pigment having excellent heat resistant water as a colorant can be used, and printing such as gravure printing is performed. In order to impart printability, the surface of the film forming the surface layer may be subjected to corona treatment.

  Moreover, it is good to contain a laser absorptive pigment | dye in printing ink. As a laser-absorbing dye, although it depends on the oscillation wavelength range of laser light, if the wavelength range is a near-infrared region centered on, for example, 800 nm, it has heat-resistant water and is a harmless inorganic compound or near-infrared absorption. It is preferable to include a coloring matter in the printing ink, the laser irradiation portion can be made excellent in laser absorbability, and the half cut portion can be efficiently formed. The laser absorbing dye layer may be printed on the printing layer 12 using a laser absorbing dye ink.

Next, the laser reflecting ink layer 13 that characterizes the present invention will be described. Laser reflective ink layer, an aluminum foil 3 to 10 wt% having a thickness foils area at 0.5μm or less containing aluminum foil fragments leafing type 20μm ² ~2000μm ² to 75%, preferably from 3 wt% to 7 It is a metallic ink containing mass%. In the ink, 15 parts by mass to 200 parts by mass of a transparent binder resin such as polyester resin, poly (meth) acrylic acid ester, vinyl chloride, polyurethane, and epoxy resin are contained with respect to 100 parts by mass of the aluminum foil. Examples of the solvent include esters, ethers, ketones, and aromatic hydrocarbons, and the viscosity of the ink is preferably 50 to 1000 cps (20 ° C., BM type rotational viscometer). The laser reflecting ink may be formed in a film thickness of 0.1 μm to 1 μm, preferably 0.2 μm to 0.5 μm, in a portion where the expiration date information 7 relating to at least the contents in the film-like laminate is formed by gravure printing.

  When the laser reflecting ink is applied and formed on the printing layer with an aluminum foil concentration of 3% by mass to 10% by mass, the leafing aluminum foil pieces are arranged and laminated so as to be folded on the printing layer, and are mirror-finished. It can be excellent in laser reflectivity. When the concentration of the aluminum foil is high, the specularity is lowered and the laser reflectivity is lowered, which is not preferable.

  The intermediate support layer 14 is a normal biaxially stretched nylon film (ON). The ON film is slightly less rigid than the PET film and has a hygroscopicity of about 7%. On the other hand, it is excellent in mechanical strength such as bending strength, piercing strength, impact strength, and tensile strength, especially at low temperatures. Since it is excellent in physical properties, it is possible to obtain a laminated film having excellent performance by complementing each other's weak points by using and combining PET films as the surface layer. The thickness of the ON film 14 is 10 to 40 μm, preferably 13 to 30 μm.

  As the barrier layer 15, an aluminum foil having a thickness of 5 to 9 μm is generally used as the oxygen barrier layer, but a film on which an inorganic material such as aluminum, alumina oxide, or silicon oxide is deposited may be used.

  Any heat seal layer 16 may be used as long as it can withstand retort processing and can be melted by heat and fused to each other. Specifically, for example, a low density polyethylene film, a medium density polyethylene film, a high density polyethylene film, a linear low density polyethylene film, a polypropylene film, an ethylene-vinyl acetate copolymer resin film, an ionomer resin film, an ethylene-acrylic acid copolymer. Polymer resin film, ethylene-ethyl acrylate copolymer resin film, ethylene-methacrylic acid copolymer resin film, ethylene-propylene copolymer film, methylpentene resin film, polybutene resin film, acid-modified polyolefin resin film, etc. Can be used. The thickness of the film is 10 to 300 μm, preferably 20 to 100 μm.

  In the present invention, it is particularly preferable to use an unstretched polypropylene resin film having excellent retort resistance as the heat seal layer. In particular, an unstretched polypropylene resin film having a melting point of 145 to 165 ° C. is preferably used for a high retort (HTST) of 120 ° C. or higher. Specifically, it is preferable to use a film made mainly of an ethylene-propylene copolymer and formed from a resin such as a propylene-ethylene random copolymer or a propylene-ethylene block copolymer. An unstretched polypropylene-based resin film obtained by adding an olefin rubber component to this, optionally adding desired additives, and kneading the composition sufficiently, for example, by extrusion, is preferable. .

In addition, the above-mentioned laser reflective ink layer, an intermediate support layer such as a polyamide resin film, a barrier layer such as an aluminum foil, and each layer of a heat seal layer are formed by a dry lamination method, a wet lamination method, an extrusion lamination method, or the like. Although it is good to laminate | stack by combining a method, a dry lamination method is preferable especially, and the polyester polyurethane type adhesive agent is used preferably as an adhesive agent in this case. Coating amount is used in the range of 0.5g / m ² ~10g / m ² in a dry state, preferably 1 to 5 g / m ² in consideration of the tear. The polyester polyurethane adhesive layer is preferable because it has little elongation and can be easily torn following each film constituting the laminate. Moreover, since it is excellent in heat resistance, it is an adhesive suitable for a retort packaging bag. The tear strength of the laminate is preferably 100 g or less when the tear strength is measured according to JIS P8116.

  The film-like laminate obtained in this way is, for example, as shown in FIG. 1, after two sheets are stacked with the heat-seal layer as the inner side, three sides are heat-sealed 2, 2, 4 After the deadline information printing part 7 is formed at the time of storing the object, the upper seal 3 is applied. In addition, the package 10 is provided with notches 5 and 5 for opening at the side seal portions 2 and 2 in the vicinity of the upper seal 3 and a cutout portion 6 starting from the notches 5 and 5. Yes.

  In the present invention, the deadline information printing part 7 relating to the contents is formed by laser irradiation from the surface layer side, but since the laser light is reflected by the laser reflecting ink layer, the laser reflecting ink layer from the outside toward the cross-sectional direction. It can be cut to the front, preventing the influence on the intermediate support layer and the barrier layer, and maintaining retort suitability. And after the contents corresponding to the term information printing part 7 are accommodated in the three-way pouch, the upper seal part is heat-sealed, and the retort packaging body of the present invention can be obtained.

  The retort package of the present invention is applicable to any type of bag such as a four-side sealed bag or a flat bag such as a pillow type bag, a self-standing bag such as a standing pouch, and a gusset bag. Can do.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
(Example)
A white ink ("Krios White" manufactured by The Inktec Co., Ltd.) with a dry film thickness of 1 μm is printed on one side of a 12 μm thick PET film (“E5100” manufactured by Toyobo Co., Ltd.), and then the printed surface is metallic. The ink (containing 10% by mass of leafing type aluminum pieces, “CLIS-silver” manufactured by The Inktech Co., Ltd.) was diluted to an aluminum piece concentration of 6% by mass and subjected to gravure printing with a dry film thickness of 1 μm.

After applying 4 g / m ² (dry state) of polyester polyurethane adhesive (“Takelac A515 / A-50” manufactured by Takeda Pharmaceutical Co., Ltd.) to the metallic printed surface of the obtained PET printed matter, the thickness is 15 μm. A laminated film was obtained by laminating a —BC-RT (ON) film (manufactured by Unitika Ltd.) by a dry lamination method.

  Next, a 7 μm thick aluminum (AL) foil is laminated on the ON film surface of the laminated film by the dry lamination method using a polyester polyurethane adhesive in the same manner as described above, and the polyester polyurethane is similarly coated on the Al foil surface. An unstretched polypropylene (CPP) film (“ZK93K” manufactured by Toray Film Processing Co., Ltd.) having a thickness of 70 μm was laminated by a dry lamination method using a system adhesive to obtain a film-like laminate having the following specifications.

  PET film (film thickness 12 μm) / printing layer (1 μm) / metallic printing layer (1 μm) / adhesive layer / ON film (15 μm) / adhesive layer / AL foil (7 μm) / adhesive layer / unstretched CPP film ( 70 μm).

(Comparative example)
In producing the film-like laminate in the examples, a film-like laminate having the following specifications was obtained in the same manner as in the examples except that the metallic ink layer was not provided.

  PET film (12 μm) / printing layer (1 μm) / adhesive layer / ON film (15 μm) / adhesive layer / AL foil (7 μm) / adhesive layer / unstretched CPP film (70 μm).

  Using the film-like laminates obtained in Examples and Comparative Examples, respectively, with the unstretched CPP film side as the inner surface, a 130 mm × 170 mm three-way pouch in the shape of FIG. 1, and a notch 5 at a location 30 mm above the pouch, 5 was applied.

  A part of the surface of the film laminate of the obtained three-way pouch is irradiated with a laser at a carbon dioxide laser (Keyence L-Z9510) 30 W (output 50%) scan speed 1500 mm / sec and an irradiation diameter of 0.4 mm. The printing part 7 was printed in the form of a barcode.

  When observing the perforation pattern (cross section) obtained in the examples and comparative examples, the PET layer and the printing layer up to the front of the metallic ink layer were perforated in the example, and the influence on the ON layer was not recognized, In the comparative example, it was found that the PET layer and the printing layer were perforated, and the ON layer was perforated to 2/3 in the thickness direction.

  Next, when the printing situation in the bags obtained in each of the example and the comparative example was observed, the example was printed with good contrast and the barcode could be read. The bar code was unreadable.

  In accordance with the food hygiene law "Standards for equipment and containers and packaging" piercing strength test, the piercing strength test was performed from the PET side (surface layer) on the bar code printed part in the three-way pouch obtained in Examples and Comparative Examples. When implemented, the example was 1.3 kg, while the comparative example was 0.7 kg, and the comparative example had a low puncture strength.

  INDUSTRIAL APPLICATION This invention is useful as a retort packaging body which is excellent in the printability to the bag body by a laser beam, and has retort suitability.

FIG. 1 is a front view showing an example of the retort package of the present invention. FIG. 2 is a cross-sectional view showing the layer structure of the film-like laminate in the retort package of the present invention. FIG. 3 is a schematic diagram for explaining a cross-sectional state of the film-like laminate in the time limit information printing unit 7 of the retort package according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 (1a, 1b) ... Film-like laminated body, 2 ... Side seal part, 3 ... Top seal part, 4 ... Bottom seal part, 5 ... Notch, 6 ... Cut-off part, 7 ... Deadline information printing part regarding contents, DESCRIPTION OF SYMBOLS 10 ... Retort packaging body, 11 ... Surface layer, 12 ... Printing layer, 13 ... Laser reflecting ink layer, 14 ... Intermediate support layer, 15 ... Barrier layer, 16 ... Heat seal layer, 17 ... Adhesive layer, 18 ... Half cut Part

Claims (6)

A film-like laminate having at least a surface layer, a laser reflective ink layer, an intermediate support layer, a barrier layer, and a heat seal layer, which is laminated in this order and having a printing layer and a laser absorbent layer between the surface layer and the laser reflective ink layer. In the packaging bag in which the surface layer side is the outside, the heat seal layer side is the content side, the peripheral edge is heat sealed, and the time limit information about the content is printed on the surface layer side, the time limit information A retort packaging body in which the film-like laminate in the printing part is half-cut from the surface layer side to the front of the laser reflective ink layer in the cross-sectional direction by laser irradiation from the surface layer side, and the expiration date information is printed. . The retort package according to claim 1, wherein the laser reflective ink layer is a metallic ink layer containing 3 to 10% by mass of metal powder. The retort package according to claim 2, wherein the metal powder is a leafing type aluminum powder. The retort packaging body according to claim 1, further comprising a printing layer between the surface layer and the laser reflective ink layer. The retort packaging body according to claim 4, wherein the printed layer contains a laser absorber. The retort packaging body according to claim 1, wherein each of the laser reflective ink layer, the intermediate support layer, the barrier layer, and the heat seal layer is laminated using an adhesive for laminating.

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