JP2011025931A - Printing method and printing apparatus for packaging material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing method and a printing apparatus for a packaging material whereby various information can be printed on the inside of a packaging material clearly while laser output is suppressed, and the adverse effects on the packaging material is suppressed. <P>SOLUTION: A metal plate member 17 is provided so as to abut on the outer surface of an innermost heat-sealable film or outermost transparent film for the packaging material 2. Using a laser marker 18 disposed opposite to the metal plate member 17 via the packaging material 2, a laser beam is emitted to a thermosensitive recording layer. Thus, the thermosensitive recording layer can be colored by causing the laser beam to enter and reflect from the metal plate member 17. Accordingly, various information can be printed on the inside of the packaging material 2 clearly while laser output is suppressed. Further, the adverse effects of pin holes or the like on the packaging material 2 is suppressed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printing method and printing apparatus for packaging materials for packaging foods and the like.

  In general, date management information such as date of manufacture, expiry date, quality control number, lot number, expiration date, etc. is displayed on packaging materials for packaging food, etc., but these management information prevents tampering. Therefore, it is possible to print the various information described above inside the packaging material by installing the recording unit inside the packaging material, irradiating laser light from the outermost layer side of the packaging material and applying heat to the recording unit. It has become.

  For example, in Patent Document 1, laser light is irradiated to a laminate in which a light color ink coating layer, a silver ink coating layer, a plastic base material layer, and a dark color ink coating layer are laminated from the outer layer to the inner layer. Thus, a printing method is disclosed in which the light ink coating layer and the silver ink coating layer are eliminated and the dark ink coating layer is exposed to provide printing information.

JP 2009-67467 A

  However, in the conventional method of printing by irradiating with laser light, if the output of the laser light is increased to increase the print density (sharpness) due to heat sensitivity, the laser light reaches the innermost sealant layer of the packaging material. In some cases, pinholes may be formed on the surface, and as a result, components that adversely affect food such as adhesive components and printing ink components may leak out. Therefore, it is considered that the allowable output of laser light that does not form pinholes in the innermost heat seal layer is set in advance. Is not practical because it is necessary to set the output of each time. In addition, the above-mentioned problems can be solved by adopting a heat-sealable film as the innermost layer of the packaging material provided with a metal vapor deposition film, but the use of the metal vapor deposition film has many disadvantages from the environmental and cost viewpoints. .

  Further, in the printing method according to the invention of Patent Document 1, the influence of laser light on the plastic substrate layer is controlled by laminating a light color ink coating layer and a silver ink coating layer on the plastic substrate layer. Although melting, breakage, pinholes and wrinkles are suppressed, the laminated structure is complicated and cannot be employed.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is capable of clearly printing various information inside the packaging material after suppressing the laser output, and a printing method and printing for the packaging material that can suppress the influence on the packaging material. An object is to provide an apparatus.

The present invention provides a packaging material printing method according to claim 1 as a means for solving the above-mentioned problems, wherein the packaging material has a heat-sensitive recording layer between the outermost transparent film and the innermost heat-sealable film. A material printing method, wherein a metal member is brought into contact with an outer surface of the innermost layer heat-sealable film or the outermost layer transparent film where the thermosensitive recording layer is located, and the metal member and a packaging material are interposed therebetween. The thermosensitive recording layer is colored by irradiating a laser beam from the facing position toward the thermosensitive recording layer.
The invention of a packaging material printing apparatus according to claim 2 is a packaging material printing apparatus having a thermal recording layer between an outermost transparent film and an innermost heat-sealable film, the position of the thermal recording layer being A metal member abutting on the outer surface of the innermost layer heat-sealable film or the outermost transparent film, and a laser beam directed toward the thermosensitive recording layer disposed so as to face the metal member via a packaging material. And an irradiating laser marker.
According to the first and second aspects of the present invention, a metal member in contact with the outer surface of the innermost layer heat-sealable film or the outermost layer transparent film is provided, and the thermosensitive recording layer is colored by the incidence of laser light and reflection from the metal member. Can do. Thereby, a laser output can be suppressed and the influence of a pinhole etc. on a packaging material can be suppressed.

The invention of the packaging material printing apparatus described in claim 3 is the invention described in claim 2, wherein the contact surface of the metal member with the outer surface of the innermost layer heat-sealable film or the outermost layer transparent film is the same. It is formed on a curved convex surface.
According to a fourth aspect of the present invention, the curved convex surface of the metal member protrudes in a curved shape along the flow direction of the packaging material. It is what.
In the inventions of claims 3 and 4, the packaging material is wrinkled at the time of laser irradiation, and between the outer peripheral surface of the curved convex surface of the metal member and the outer surface of the innermost layer heat-sealable film or outermost layer transparent film. Since the gaps can be removed so that they are brought into close contact with each other, irregular reflection of the laser beam from the metal member can be prevented, and the heat-sensitive recording layer can be clearly colored. When irregular reflection by laser light occurs, the printed font is partially thinned or distorted and the outline of the font becomes unclear.

According to a fifth aspect of the present invention, there is provided a printing apparatus for packaging material according to the third or fourth aspect, wherein the metal member is a printing roller.
In the invention of claim 5, since the metal member is employed as the printing roller, the configuration of the apparatus is simplified without complicating and the cost is reduced.

  According to the packaging material printing method and printing apparatus of the present invention, various information can be clearly printed inside the packaging material while suppressing the laser output, and the influence on the packaging material can be suppressed.

FIG. 1 is a schematic view of a packaging material printing apparatus according to a first embodiment of the present invention. FIG. 2 is a view of a metal plate member, (a) is a front view, and (b) and (c) are side views. FIG. 3 is a schematic view of a packaging material printing apparatus according to a second embodiment of the present invention. FIG. 4 is a cross-sectional view of the packaging material. FIG. 5 is a diagram illustrating a result of evaluating a printing state when printing rollers having various diameters are used for a plurality of printing ranges.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to FIGS.
First, the packaging material 2 for packaging food and the like will be described with reference to FIG.
As shown in FIG. 4, the packaging material 2 includes a heat-sensitive recording layer 8 in contact with the inner surface of the outermost transparent film 3 between the outermost transparent film 3 and the innermost heat-sealable film 4, and the heat-sensitive recording. A protective coating comprising a first protective coating layer 5 which is inactive to the heat-sensitive recording layer 8 covering the layer 8 and a second protective coating layer 6 disposed so as to cover the first protective coating layer 5. The work layer 7 and the adhesive layer 10 are sequentially stacked and arranged, and the entire structure is joined and integrated. In addition, the white printing layer 11 is laminated | stacked between the 2nd protective coating layer 6 and the adhesive bond layer 10 of the protective coating layer 7 as needed.

  The outermost transparent film 3 can be used as long as it is a synthetic resin film used for packaging materials for ordinary packaged foods. However, since the information recording method is a thermal recording method, the heat-resistant synthetic resin film is used. It is desirable that For example, a biaxially stretched polyester film or a biaxially stretched polypropylene film is preferable. The thickness of the outermost transparent film 3 is not particularly limited as long as the layer is not destroyed when heat is applied by the thermal recording method. Usually, the thing of 8 micrometers-60 micrometers is used.

  The innermost layer heat sealable film 4 is provided for preventing contact between the intermediate layer of the packaging material 2 and the stored food and for sealing the packaging material 2 by heat sealing. The innermost layer heat-sealable film 4 is made of a polyolefin film or the like that can be heat-melted and bonded, and can easily form the laminated packaging material 2 into a cylindrical or bag shape using a heat-seal bar. Is.

  The heat-sensitive recording layer 8 is preferably a layer containing a leuco dye as a color former. The leuco dye used as the color former in the recording layer of the thermal recording system has excellent thermochromic properties, such as 3-isopentylethylamino-6-methyl-7-anilinofluorane, 3- Dipentylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3- (N -Ethyl-p-toluidino) -7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane.

  As the developer, 4,4′-dihydroxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, p -Hydroxybenzoic acid benzyl ester and the like.

The protective layer can be formed without adversely affecting the leuco dye of the heat-sensitive recording layer 8, and is formed from an organic solvent used in the adhesive layer 10 and the printing layer, and other organic compound components. There is no particular limitation as long as it is a layer that can block the influence and protect the thermosensitive recording layer 8, but no layer forming material that can satisfy such a requirement as a single layer is known.
Therefore, the protective layer of the thermal recording layer 8 that does not adversely affect the color former of the thermal recording layer 8 is inactive to the thermal recording layer 8 formed in contact with and covering the thermal recording layer 8. The first protective coating layer 5 and the second protective layer that is formed as a coating layer covering the first protective coating layer 5 is excellent in barrier properties against the components of the adhesive layer 10 and the printed layer components. The protective coating layer 7 formed by laminating the protective coating layer 6 is particularly excellent.

The coating amount of the protective coating layer 7 as a whole ^{0.2g / m 2 ~10g / m 2} , and preferably from ^{2.0g / m 2 ~4.0g / m 2} . It is less than 0.2 g / m ² may not be able to fulfill sufficiently the functions required for the protective layer of the heat-sensitive recording layer 8, even if coating reversed beyond 10 g / m ^2, a coated amount of An effect commensurate with the increase in the amount cannot be obtained. The protective layer of the heat-sensitive recording layer 8 needs to be a layer coated so as to cover at least the entire heat-sensitive recording layer 8, but may be a coated layer covering a wider range.

The first protective coating layer 5 on the heat-sensitive recording layer 8 side is a layer formed with an aqueous coating solution, such as an acrylic emulsion coating solution that does not adversely affect the leuco dye of the heat-sensitive recording layer 8. A layer to be formed is preferable. When using an acrylic emulsion coating liquid, it is preferable to use an acrylic emulsion coating liquid in which the coating liquid is a nonionic type. The coating amount of the first protective coating layer 5 such as an acrylic emulsion coating layer is ^{0.1g / m 2 ~5g / m 2} , and preferably from ^{1.0g / m 2 ~2.0g / m 2} . If it is less than 0.1 g / m ² , it may not be possible to completely prevent the effect of the organic solvent blocking coating layer to be applied to the heat-sensitive recording layer 8, and if it exceeds 5 g / m ² Even if it works, the effect commensurate with the increase in coating amount is not obtained. On the contrary, it is not preferable because it becomes a coating layer having poor flexibility and may deteriorate the barrier property as the protective layer of the heat-sensitive recording layer 8 during handling of the packaging material.

The second protective coating layer 6 on the adhesive layer 10 side blocks the influence of the organic solvent used in the adhesive layer 10 and the printing layer, the adhesive component and the printing layer component on the thermal recording layer 8. It is a layer to do. The print layer refers to the white print layer 11 and the print information layer. The second protective coating layer 6 is composed of a urethane emulsion coating solution, a polyvinyl alcohol aqueous solution, a vinyl acetate emulsion coating solution, a vinyl chloride emulsion coating solution, a vinylidene chloride emulsion coating solution, and an epoxy emulsion coating solution. And a layer formed by an aqueous coating solution selected from the group consisting of urethane-acrylic composite emulsion coating solutions. The coating amount of these layers ^{0.1g / m 2 ~5g / m 2} , and preferably from ^{1.0g / m 2 ~2.0g / m 2} . If it is less than 0.1 g / m ² , the blocking property of the organic solvent or the like may be insufficient, and even if the coating exceeds 5.0 g / m ² , the organic solvent or the like suitable for the increase in coating amount The blocking effect is not obtained.

The white print layer 11 is a layer for raising the black record information recorded on the heat-sensitive recording layer 8 so that the black record information can be easily seen, and is laminated as necessary. The white print layer 11 is formed as a print layer using white ink. The white ink is preferably an ink containing a white pigment such as titanium white, but is not particularly limited. A material containing a white pigment other than titanium white can be used as long as the printed layer does not adversely affect the heat-sensitive recording layer 8.
The white print layer 11 needs to be a layer that covers at least the heat-sensitive recording layer 8, but may be a layer provided over other print layer portions. The coating amount of this layer is not particularly limited as long as the whiteness that makes the recorded information of the heat-sensitive recording layer 8 and the recorded information of other printed layers easy to see is achieved, and is generally 2.0 g / in the range of ^{m 2} ~6.0g / m ^2.

The adhesive layer 10 is a layer coated on the innermost layer heat-sealable film 4 side of the protective coating layer 7 of the heat-sensitive recording layer 8 and is a layer for joining and integrating the entire laminate. As an adhesive used for the adhesive layer 10, those used as an interlayer adhesive for laminated films used for ordinary food packaging materials and the like can be used. For example, a polyurethane system, an acrylic system, an epoxy system, etc. are mentioned, However, In the packaging material 2 in this Embodiment, a polyurethane system is preferable. The coating amount of the adhesive layer 10 is not particularly limited as long as the entire laminate is bonded and integrated, and an adhesive force that does not cause interphase peeling or the like when used as the packaging material 2 is obtained. The range is from 0.0 g / m ^{2 to} 6.0 g / m ² .

  The packaging material 2 is formed by printing the heat-sensitive recording layer 8 on the inner surface of the outermost transparent film 3 and includes the first and second protective coating layers 5 and 6 so as to cover at least the entire surface of the heat-sensitive recording layer 8. After forming the protective coating layer 7 and forming the white printing layer 11 so as to cover at least the entire surface of the protective coating layer 7 as required, an adhesive is applied to the entire inner surface of the outermost layer (adhesive layer) 10), and the innermost layer heat-sealable film 4 is laminated and pressed and bonded.

Next, the printing apparatus 1a according to the first embodiment of the present invention will be described based on FIGS. 1 and 2 and with reference to FIG.
As shown in FIG. 1, the printing apparatus 1 a according to the first embodiment of the present invention has an outer surface of the innermost layer heat-sealable film 4 where the heat-sensitive recording layer 8 of the packaging material 2 drawn out from the roll-shaped body 15 is located. The metal plate member 17 that is in contact with the metal plate member 17 is disposed so as to face the metal plate member 17 with the packaging material 2 therebetween, and laser light is directed toward the heat-sensitive recording layer 8 from the outermost transparent film 3 side of the packaging material 2. And a laser marker 18 for irradiation.
In the first embodiment, the metal plate member 17 is brought into contact with the outer surface of the innermost layer heat-sealable film 4 where the thermal recording layer 8 is located, and laser light is emitted from the outermost transparent film 3 side. The metal plate member 17 is brought into contact with the outer surface of the outermost transparent film 3 where the heat-sensitive recording layer 8 is located, and laser light is directed toward the heat-sensitive recording layer 8 from the innermost heat-sealing film 4 side. May be irradiated.

  As shown in FIGS. 1 and 2, the metal plate member 17 includes an outer surface of the innermost layer heat-sealable film 4 in a range where the heat-sensitive recording layer 8 of the packaging material 2 is formed between the guide rollers 16a and 16a. It arrange | positions so that it may contact | abut. As shown in FIG. 2A, the metal plate member 17 is formed in a substantially rectangular shape when viewed from the front, and the contact surface with the innermost layer heat sealable film 4 is as shown in FIGS. 2B and 2C. As shown, it protrudes in a curved shape with a predetermined curvature R1 along the flow direction of the packaging material 2, while extending in the horizontal direction in the range W in the direction orthogonal to the flow direction of the packaging material 2, both ends in the width direction have a predetermined curvature. It is formed on a curved convex surface 19 that curves at R2. In the present embodiment, the predetermined curvature R1 of the curved convex surface 19 is set to an appropriate value of 1200 mm to 2450 mm, and the predetermined curvature R2 is set to an appropriate value of 10 mm to 15 mm. Reference numerals 26 shown in FIGS. 2B and 2C are mounting screws for mounting the metal plate member 17 to the frame of the apparatus.

表１から解るように、図２（ｂ）及び（ｃ）も参照して、湾曲凸状面１９の所定曲率Ｒ１が１２００ｍｍまたは２４５０ｍｍ、水平面の幅Ｗが３０ｍｍ、幅方向両端の所定曲率Ｒ２が１０ｍｍの寸法を採用した時にシワが無くなり、また、所定曲率Ｒ１が２４５０ｍｍ、水平面の幅Ｗが３０ｍｍ、幅方向両端の所定曲率Ｒ２が１５ｍｍの寸法を採用した時にシワが無くなることが解った。 Therefore, Table 1 shows the result of evaluating the presence or absence of wrinkles of the packaging material 2 due to the difference in the surface shape of the curved convex surface 19 of the metal plate member 17.

As can be seen from Table 1, with reference also to FIGS. 2B and 2C, the predetermined curvature R1 of the curved convex surface 19 is 1200 mm or 2450 mm, the width W of the horizontal plane is 30 mm, and the predetermined curvature R2 at both ends in the width direction is It has been found that wrinkles are eliminated when a dimension of 10 mm is adopted, and wrinkles are eliminated when a dimension having a predetermined curvature R1 of 2450 mm, a horizontal width W of 30 mm, and a predetermined curvature R2 at both ends in the width direction of 15 mm is adopted.

When the curved convex surface 19 of the metal plate member 17 is brought into contact with the outer surface of the innermost layer heat-sealable film 4 of the packaging material 2, as described above, there is no wrinkle at the contact portion of the packaging material 2, and The gap between the curved convex surface 19 of the metal plate member 17 and the outer surface of the innermost layer heat-sealable film 4 of the packaging material 2 is eliminated, so that they are in close contact with each other. Thereby, irregular reflection of the laser beam from the metal plate member 17 can be prevented, and the heat-sensitive recording layer 8 can be vividly colored.
In the case where there is no wrinkle or the like in the range of the heat-sensitive recording layer 8 of the packaging material 2, it is not necessary to provide the curved convex surface 19 on the metal plate member 17.

  The laser beam can be appropriately selected according to the type and thickness of the laminated member constituting the packaging material 2, and is not particularly limited as long as it can be used for laser marking. For example, a carbon dioxide laser, a YAG laser, a semiconductor laser, or the like can be used. Irradiation output, printing speed, and the like can also be appropriately selected according to the type and thickness of the laminated member constituting the packaging material 2. In the present embodiment, a laser marker 18 having a maximum laser output of 30 W is used as the laser beam.

Next, a printing method using the printing apparatus 1a according to the first embodiment described above will be described.
The packaging material 2 drawn out from the roll-shaped body 15 is guided to a predetermined path by a plurality of guide rollers 16 and 16a. Subsequently, the outer surface of the innermost layer heat-sealable film 4 of the packaging material 2 is brought into contact with the metal plate member 17 between the guide rollers 16 a and 16 a. As a result, the wrinkles at the contact portion of the packaging material 2 are extended by the curved convex surface 19 of the metal plate member 17, and further, the curved convex surface 19 of the metal plate member 17 and the innermost layer heat seal of the packaging material 2. The gap between the outer surfaces of the conductive films 4 is eliminated and the respective films are in close contact with each other. At this time, the laser marker 18 irradiates laser light from the outermost transparent film 3 side of the packaging material 2 toward the heat-sensitive recording layer 2, and various types of information are colored on the heat-sensitive recording layer 8 of the packaging material 2.
In this embodiment, the output of the carbon dioxide laser is set to an appropriate value of 10 to 30 W, preferably 15 to 25 W, and the printing speed is set to an appropriate value of 1000 to 5000 mm / second, preferably 1500 to 2500 mm / second. Is set.

  Thereafter, when printing on the packaging material 2 is completed, the packaging material 2 flows along the guide rollers 16, and the food enters under the packaging material 2 immediately before the bag making device 20 formed of a metal frame. 2 is formed in a cylindrical shape so as to wrap the food by the bag making machine 20. Subsequently, the cylindrical end portions of the packaging material 2 are sealed along the flow direction of the packaging material 2 by the center seal bar 21, and the upstream and downstream end openings of the cylindrical packaging material 2 are finally at the top. Each package is sealed with a seal bar 22 to form a package 23 in the form of a product. Reference numeral 24 denotes a pinch roller.

  As described above, in the printing apparatus 1a according to the first embodiment of the present invention, the metal plate member 17 that contacts the outer surface of the innermost layer heat-sealable film 4 or the outermost layer transparent film 3 of the packaging material 2 is provided, Laser light is irradiated toward the thermal recording layer 8 by a laser marker 18 disposed at a position facing the metal plate member 17 and the packaging material 2. Thereby, since the heat-sensitive recording layer 8 can be colored by the incidence of laser light and reflection from the metal plate member 17, the output of the laser light can be suppressed, and pinholes or the like to the packaging material 2 by laser irradiation can be suppressed. The influence can be suppressed. Further, as a merit of printing performance, printing can be performed using reflection of laser light from the metal plate member 17.

  Further, in the printing apparatus 1 a according to the first embodiment of the present invention, the metal plate member 17 has the packaging material 2 on the contact surface with the outer surface of the innermost layer heat sealable film 4 or the outermost layer transparent film 3. Since the curved convex surface 19 that curves along the flow direction is provided, the wrinkles at the contact portion of the packaging material 2 (range of the heat-sensitive recording layer 8) can be extended, and the innermost layer heat-sealable film 4 Alternatively, since there is no gap between the outer surface of the outermost transparent film 3 and the curved convex surface 19 of the metal plate member 17, and each can be brought into close contact, it is possible to prevent irregular reflection of laser light from the metal plate member 17. And the thermosensitive recording layer 8 can be vividly colored.

Next, a printing apparatus 1b according to a second embodiment of the present invention will be described based on FIGS. 3 and 5 and with reference to FIG.
As shown in FIG. 3, the printing apparatus 1b according to the second embodiment of the present invention employs a printing roller 25 instead of the metal plate member 17 employed in the printing apparatus 1a according to the first embodiment. Other configurations are substantially the same as those of the printing apparatus 1a according to the first embodiment.
The diameter of the printing roller 25 employed in the printing apparatus 1b according to the second embodiment is set to an appropriate value of 20 to 120 mm, preferably 40 to 80 mm, although it varies depending on the printing range.
FIG. 5 shows the result of evaluating the printing state when each printing roller 25 having various diameters is used for a plurality of printing ranges.
Referring to FIG. 5, when the diameter of the printing roller 25 is 20 mm, the distortion of printing is large and the character can be read. In addition, since the date management information such as the expiration date normally falls within the range of 20 mm, if the print range is 10 mm or 15 mm, the print state is good regardless of whether the diameter of the print roller 25 is 40 mm, 60 mm, or 80 mm. If the printing range is 20 mm, the printing roller 25 has a diameter of 80 mm, and the printing state is good.

As shown in FIG. 3, the outer surface of the outermost transparent film 3 of the packaging material 2 is brought into contact with the printing roller 25, and the wrinkles at the contact portion of the packaging material 2 are extended by the curved surface of the printing roller 25. In addition, there is no gap between the outer surface of the outermost transparent film 3 and the curved surface of the printing roller 25, so that they are in close contact with each other. At this time, laser light is irradiated from the innermost layer heat-sealable film 4 side of the packaging material 2 toward the heat-sensitive recording layer 8 by the laser marker 18, and various types of information are colored on the heat-sensitive recording layer 8 of the packaging material 2.
In the second embodiment, the printing roller 25 is brought into contact with the outer surface of the outermost transparent film 3 where the thermal recording layer 8 is located, and laser light is emitted from the innermost heat sealable film 4 side. As in the first embodiment, the printing roller 25 is brought into contact with the outer surface of the innermost layer heat-sealable film 4 where the heat-sensitive recording layer 8 is located, and laser light is emitted from the outermost layer transparent film 3 side. May be irradiated toward the thermosensitive recording layer 8. That is, the guide roller 16b shown in FIG. 3 can be used as a print roller, and the print roller 25 can be used as a guide roller.

And also in the printing apparatus 1b which concerns on the 2nd Embodiment of this invention, there can exist an effect similar to the printing apparatus 1a which concerns on 1st Embodiment.
In addition, by adopting the printing roller 25, the entire apparatus can be simplified and the cost can be suppressed.

DESCRIPTION OF SYMBOLS 1a, 1b Printing apparatus, 2 Packaging material, 3 Outermost layer transparent film, 4 Innermost layer heat sealable film, 8 Thermal recording layer, 17 Metal plate member, 18 Laser marker, 19 Curved convex surface, 25 Printing roller

Claims (5)

A printing method for a packaging material having a heat-sensitive recording layer between an outermost layer transparent film and an innermost layer heat-sealable film,
The thermosensitive recording layer from a position facing the metal member with a packaging material in a state where the metal member is in contact with the outer surface of the innermost layer heat-sealable film or the outermost transparent film where the thermosensitive recording layer is located. A method for printing a packaging material, which comprises irradiating a laser beam toward the surface to cause the heat-sensitive recording layer to develop color. A packaging material printing apparatus having a heat-sensitive recording layer between an outermost layer transparent film and an innermost layer heat-sealable film,
A metal member in contact with the outer surface of the innermost layer heat-sealable film or the outermost layer transparent film where the thermosensitive recording layer is located;
A laser marker that is arranged so as to face the metal member and the packaging material and irradiates a laser beam toward the thermosensitive recording layer;
A printing apparatus for packaging materials, comprising:   The printing apparatus for packaging materials according to claim 2, wherein a contact surface of the metal member with an outer surface of the innermost layer heat-sealable film or the outermost layer transparent film is formed into a curved convex surface. .   The printing apparatus according to claim 3, wherein the curved convex surface of the metal member protrudes in a curved shape along a flow direction of the packaging material.   5. The packaging material printing apparatus according to claim 3, wherein the metal member is a printing roller.

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