JP2007038594A - Laminated film for packaging, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated film for packaging which can form characters, marks or the like without being subject to a constraint on design, and without exposing either surface of the laminated plastic film itself, and wherein the fear for the adhesion of droplets of an inject to an unintended section, and the fear for the splashing of an ink solvent in a food factory have been eliminated. <P>SOLUTION: In either interlaminar space of two layers or more of transparent plastic films which are laminated to each other, an ink layer of a high laser beam absorbing rate is provided. An ink in the ink layer is locally sublimated, dissipated or eliminated, and a part of the ink layer is fractured. Thus, at least one kind of characters, figures and marks is formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a laminated film for packaging suitable for use in food packaging and a method for producing the same. For example, a production place, a production date, an expiration date, other characters, symbols, figures, etc. The present invention proposes a technique for forming the film without exposing it to the inner or outer surface of the film.

  The applicant has not been exposed to either the outer surface or the inner surface of the flexible packaging bag, and thus information such as the manufacturing location and the manufacturing date is not lost due to external friction. Patent Document 1 discloses a technique for providing an ink layer display on a packaging bag that is not in direct contact with foods or the like as a packaged object and that is always easy and reliable in reading.

This is because, for example, in automatic filling packaging, an ink layer that displays required characters, symbols, etc. is provided in the vicinity of the guide roll on the portion of the heat seal layer of the packaging film that is being fed out and subjected to vertical sealing. According to this, the ink layer is sandwiched between the heat seal layers at the vertical seal portion of the packaging bag after the automatic filling packaging is finished. As a result, exposure to the inner and outer surfaces of the packaging bag is reliably prevented.
JP-A-8-91391

  However, in the proposed technique, since the ink layer cannot be displayed except for the vertical seal portion of the packaging bag, there is a problem in that the design restrictions on the packaging bag are large, including including the ink layer display on the horizontal seal portion. In addition, there was a problem that ink jet splashes could not be completely wiped away from the concern of adhering to the contact surface of the packaging film with the object to be packaged beyond the vertical seal portion, and the organic solvent of the ink Could not be denied that it could diffuse into food factories and contaminate the environment.

  An object of the present invention is to solve such problems of the prior art, and the object of the present invention is to provide a laminated plastic without characters, symbols, etc. being restricted in design. It can be formed without exposing it to any surface of the film itself, and accidental adhesion of ink jet droplets to unintended parts of the packaging film and diffusion of ink solvents in food factories It is in providing the laminated film for packaging which removed the fear of this, and its manufacturing method.

  The laminated film for packaging according to the present invention includes an ink layer formed on an ink layer having a high laser light absorptivity provided between layers of two or more transparent plastic films that transmit laser beams. By partially sublimating, disappearing, or eliminating the ink constituting the ink by irradiation with a laser beam, a part of the ink layer is destroyed afterwards, and at least one of a letter, a figure, and a symbol to be drawn in the ink layer It forms a kind.

  Here, ink sublimation (including evaporation), destruction of the ink layer due to disappearance or exclusion means that the portion of ink irradiated with laser light absorbs near-infrared light emitted by the laser and generates heat, For example, the urethane-based organic material constituting the ink begins to melt, and the melted ink is removed to the peripheral portion by the impact of the laser (at least temporarily dispersed between the laminated films until cooled) Depending on the situation.) In addition, when the laser beam irradiation is strong, the ink in the irradiated portion is dispersed and disappears by temporarily foaming, decomposing, scattering or gasifying between the laminated films. When gasified, the film layer of the printed portion is slightly delaminated and floats, but this portion is brought into close contact again by cooling, so there is no problem.

  Here, preferably, the ink layer is a urethane black gravure ink layer, and preferably, the thickness of the ink layer is 0.1 to 5 μm, more preferably 1 μm or less.

  By the way, the ink layer is preferably a printed layer printed on the surface of a uniaxially or biaxially stretched stretched base film, mostly with other required designs. In this case, it is preferable to provide an ink layer of another color with a high laser light transmittance on one side of the ink layer on the surface of the stretched base film, particularly when there is a white ink layer. The density difference appears and the printing becomes clear.

  Moreover, the manufacturing method of the laminated film for packaging according to the present invention destroys a part of the ink layer having a high laser light absorptivity provided between any two of the two or more transparent plastic films laminated to each other. Thus, in forming at least one of characters, figures and symbols, the laminated plastic film is irradiated with a laser beam from, for example, the stretched base film layer side or the sealant layer side in the ink layer. The ink is sublimated, disappeared or eliminated to destroy it locally.

  In this case, the laminated plastic film is preferably irradiated with a YVO4 laser beam having a wavelength in the near infrared region of 1064 nm. This YVO4 laser beam enables fine marking such as small characters and processing, and is excellent in high-speed printability. In particular, the single mode beam can be printed with uniform and particle-less light beam, excellent laser power stability, and printing with no unevenness. In addition, when using a carbon dioxide laser or the like, if the laser light irradiation on the laminated plastic film is too strong, it is difficult to check with the naked eye, but only the character part on the film surface is slightly torn, There may be scratches. In this respect, the YVO4 laser has a feature that it can print out letters and the like without scratching because it can perform fine power adjustment.

  In the laminated film for packaging according to the present invention, for example, a predetermined ink layer is formed on a transparent stretched base film by gravure printing or the like, and a transparent plastic film is laminated on the ink layer side as necessary. In addition, by forming letters, figures, etc. in the ink layer sandwiched as an intermediate layer, it is possible to reliably prevent the letters, figures, etc. from being exposed to the surface of the laminated film for packaging. Arbitrary selection including a required seal portion, such as a formation mode, is possible, and the degree of freedom in design can be greatly increased.

  Further, according to this, after the ink layer is formed on the stretched base film, the ink layer is completely covered with the other laminated transparent plastic film, so that the ink layer or the like is in contact with an object to be packaged. In addition to reliably removing the possibility of accidental adhesion to the portion, the risk of diffusion of the ink solvent in the food factory can be completely removed.

  In such a laminated film, when the ink layer is a urethane-based black gravure ink layer, the absorption rate of the laser beam can be further increased by making the ink layer black. Also, by forming the ink layer with a urethane-based organic material, the ink absorbs near-infrared light emitted by the laser and melts when it generates heat, and the melted ink is removed to the periphery by the impact of the laser. be able to.

  The thickness of the ink layer is, for example, in the range of 0.1 to 5 μm, preferably about 1 μm or less.

  Here, when the ink layer is a uniaxial or biaxially oriented stretched base film, for example, a printed layer on the inner surface with polarity, the ink layer is formed simultaneously with other design printed layers, etc. And a step for separately forming the ink layer can be omitted, so that the cost of the laminated film for packaging can be reduced.

  By the way, in this case, when another ink layer having a high laser light transmittance and another color is provided on either side of the ink layer on the surface of the stretched base film, By irradiation, the above ink layer locally sublimates, disappears, or eliminates in a form corresponding to characters, figures, etc., so that the letters, figures, etc. are made clearer through other ink layers. Can be displayed.

  In the method for manufacturing a laminated film for packaging according to the present invention, when forming characters, figures, etc. on the ink layer provided between any two or more of the laminated transparent plastic films, Compared to the conventional technique in which ink layer display is performed by an ink jet printer by irradiating a laser beam from one of the surface sides to locally destroy the ink layer to form characters, figures, etc. All the problems caused by the splashing of the droplets, the diffusion of the ink solvent, etc. can be solved completely.

  Further, in this case, when the laser beam to be irradiated is a YVO4 laser beam having a wavelength of 1064 nm, unlike the carbon dioxide laser, fine power adjustment can be performed, so that characters such as letters can be printed without scratching.

  FIG. 1 is an enlarged cross-sectional view illustrating a laminated plastic film that can be used in the production of a laminated film for packaging according to the present invention. In the figure, 1 is a transparent film that is uniaxially or biaxially stretched and transmits laser light. A stretched base film, for example, a stretched base film made of polypropylene, polyester, polyamide, etc., 2 is a required formation area of characters, figures, etc. 2 shows an ink layer having a high laser light absorptance formed beyond the upper limit. The ink layer 2 is preferably a urethane black gravure printing layer, and preferably has a thickness in the range of 0.1 to 5 μm, more preferably 1 μm or less.

Reference numeral 3 denotes a sealant layer laminated on the ink layer 2, and this transparent sealant layer 3 which also transmits laser light is formed of, for example, unstretched polypropylene, polyethylene or the like to form the ink layer 2. Cover the area completely throughout. Therefore, the possibility that the ink layer 2 comes into contact with an article to be packaged packaged on the sealant layer 3 side is sufficiently removed.
In this figure, the sealant layer 3 is directly laminated on the ink layer 2, but one or more transparent intermediate layers that transmit laser light are laminated between the ink layer 2 and the sealant layer 3. You can also.

FIG. 2 is a schematic partial cross-sectional view illustrating the form of characters, figures, etc. on the ink layer of the laminated plastic film as described above. Here, the wavelength irradiated from the laser beam irradiation head 4 is shown in FIG. Is focused to the ink layer 2 of the laminated plastic film 6 by the condenser lens 5.
In this case, the laser beam can be irradiated from any surface side of the laminated plastic film 6, but according to the enlarged cross-sectional view of the main part shown in FIG. 3, the laser beam was irradiated from the stretched base film 1 side. The laser beam passes through the base film 1 and locally destroys (sublimates, disappears or eliminates) the ink layer 2, and then passes through the sealant layer 3. As a result, the laser beam for packaging according to the present invention is used. The laminated film 7 is manufactured.

  Therefore, for example, by scanning the laminated plastic film 6 with a laser beam according to required characters, figures, etc., the ink layer 2 is caused to destroy (sublimation, disappearance or exclusion) as expected. At least one kind of character, figure and symbol can be formed, and the character, figure and the like can be clearly and reliably visually recognized from, for example, the stretched base film side. And this means that another ink layer having a high laser beam transmittance, for example, white is laminated on the sealant layer 3 side of the ink layer 2, and the brightness difference from the white ink layer of the non-destructive portion of the black ink layer is reduced. This is particularly noticeable when the size is increased.

  By the way, such irradiation of the laser beam prevents the stretched base film 1 and the sealant layer 3 from being perforated by excessive irradiation energy of the laser beam, and the laser output, frequency, displacement speed, etc. It is important to control.

It is an expanded sectional view which illustrates the laminated plastic film which can be used for implementation of the method concerning this invention. It is an approximate line fragmentary sectional view showing an embodiment of a method concerning this invention. It is a principal part expanded sectional view which shows embodiment of the laminated film for packaging which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stretched base film 2 Ink layer 3 Sealant layer 4 Irradiation head 5 Condensing lens 6 Laminated plastic film 7 Laminated film for packaging

Claims (7)

  An ink layer having a high laser light absorption rate provided between any two or more transparent plastic films laminated on each other, and the ink in the ink layer is locally sublimated, disappeared or disappeared by laser beam irradiation. A laminated film for packaging formed by forming at least one of characters, figures and symbols by eliminating and destroying a part of the ink layer.   The laminated film for packaging according to claim 1, wherein the ink layer is a urethane black gravure ink layer.   The laminated film for packaging according to claim 1 or 2, wherein the thickness of the ink layer is in the range of 0.1 to 5 µm.   The laminated film for packaging according to any one of claims 1 to 3, wherein the ink layer is used as a printed layer on a stretched base film.   The laminated film for packaging according to claim 4, wherein another ink layer having a high laser light transmittance and having another color is provided on the ink layer on the surface of the stretched base film. In forming at least one of characters, figures and symbols by destroying a part of an ink layer having a high laser light absorption rate provided between any two or more transparent plastic films laminated on each other ,
Production of a laminated film for packaging, wherein the ink layer is irradiated with a laser beam from the outside of the laminated plastic film so that the ink in the ink layer is sublimated, disappeared or eliminated and locally destroyed. Method. The method for producing a laminated film for packaging according to claim 6, wherein the laminated plastic film is irradiated with a YVO4 laser beam having a wavelength of 1064 nm.

Images