JP2019010822A - Method of producing package and ink composition - Google Patents

Abstract

To provide a method of producing a package capable of achieving faster and more efficient image formation to the package.SOLUTION: A method of producing a package of this invention includes: a preparation step of obtaining a cardboard sheet including a laser coloring layer using an ink composition containing a component that irreversibly forms color with laser radiation; a forming step of forming a cardboard carton using the cardboard sheet; and a laser image formation step of forming an image by radiating a laser beam to the laser coloring layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a package and an ink composition. More specifically, the present invention relates to a method for producing a package using laser marking technology and an ink composition suitably used for laser marking.

In recent years, a technique (laser marking technique) in which an image is formed by irradiating a laser beam to a component that irreversibly develops color by irradiation with the laser beam has been actively studied. In particular, studies on laser marking on packaging (packaging material) of articles are actively conducted.
Patent Document 1 describes a laser marking composition comprising a binder and an oxyanion of a polyvalent metal for the purpose of performing machine reading marking such as a barcode on a packaging material. In Examples of Patent Document 1, a laser color-forming composition is printed on a substrate such as a carton board or a polypropylene film (gravure printing or flexographic printing), or the substrate is irradiated with laser light to form an image. The formation is described.
Patent Document 2 discloses a method of generating a multi-color barcode or two-dimensional code by irradiating a laser, and a composition used in the method.
Patent Document 3 describes a coating composition containing a color former, an amine salt of an organometallic compound defined by the general formula, a binder, and a solvent. In particular, the examples describe that the coating composition was applied to paper or plastic to obtain a coating.
Patent Document 4 describes an ink composition capable of laser marking, which contains a laser color former such as copper phenylphosphonate or copper / molybdenum composite oxide, and a binder resin such as urethane resin or acrylic resin. It also describes that the recording material was obtained by printing the composition on a PET (polyethylene terephthalate) film or paper using a gravure plate.
Patent Document 5 describes a packaging film having a white ink layer using titanium oxide sandwiched between a surface layer film and a sheet layer film as a colorant as a method for performing laser marking on a packaging film such as polyethylene. .

JP-T-2004-522631 Special table 2012-502383 gazette Special table 2008-538548 gazette JP 2007-313875 A JP, 2006-137719, A

  As described above, an image forming technique for a packaging material by laser marking has been actively studied. However, the fact that an image can be formed on a packaging material using the laser marking technology alone does not provide an active motivation to replace the current image forming technology (thermal printing or ink jet printing) on the packaging material with the laser marking technology. In order to spread the image forming technology on the packaging material by laser marking, it is required that the image forming (printing) on the packaging material can be speeded up and made efficient by using the characteristics of the laser marking technology.

  In view of such circumstances, an object of the present invention is to provide a method for manufacturing a packaging material capable of speeding up and improving the efficiency of image formation on the packaging material.

  As a result of the study, the present inventors made the invention provided below.

According to the present invention,
Using an ink composition containing a component that irreversibly develops color by laser irradiation, a preparation step for obtaining a corrugated cardboard sheet equipped with a laser coloring layer;
An assembly step of assembling a cardboard box using the cardboard sheet;
And a laser image forming step of forming an image by irradiating the laser coloring layer with laser light.

Moreover, according to the present invention,
According to the method for manufacturing a package, the first package and the second package are manufactured.
A method for manufacturing a plurality of packaging bodies, wherein an image formed on the first packaging body in the laser image forming step and an image formed on the second packaging body in the laser image forming step are different from each other. Provided.

Moreover, according to the present invention,
An ink composition comprising a component that irreversibly develops color by laser irradiation,
Provided is an ink composition comprising inorganic metal oxyanion compound particles and / or a combination of a color former and compound particles represented by the following general formula (I) as a component that irreversibly develops color by laser irradiation Is done.

According to the present invention, when a package is manufactured, printing on the package can be performed quickly and efficiently.
Specifically, if a cardboard box provided with a laser coloring layer is manufactured and stored in advance by the above preparation process and assembly process, then laser image formation is performed on the cardboard box in accordance with a customer order or the like. Thereby, the package which has a desired image can be manufactured rapidly and efficiently. In addition, by performing image formation with a laser, it is not necessary to prepare a separate material for image formation like ink for ink jet printing.

It is a flowchart for demonstrating an example (1st Embodiment) of the manufacturing method of the package of this invention. 1A is a schematic diagram of the first embodiment, FIG. 1B is a diagram for specifically explaining the “preparation process” in FIG. 1A, and FIGS. 1C and 1D are modified examples of the “preparation process” (modification examples 1 and It is a figure for demonstrating specifically the modification 2). It is a flowchart for demonstrating an example (2nd Embodiment) of the manufacturing method of the package of this invention. It is a figure (sectional view) showing typically an example of an apparatus used at a preparation process. It is a figure (sectional drawing) which shows typically another example of the apparatus used at a preparation process. It is a figure (sectional drawing) which shows typically another example of the apparatus used at a preparatory process.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all the drawings, the same components are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
All the drawings are schematic for explanation only. The shape and dimensional ratio of each member in the drawing do not necessarily correspond to an actual article.

In this specification, the term “substantially” means that it includes a range that takes into account manufacturing tolerances, assembly variations, and the like, unless otherwise specified.
In the present specification, the notation “ab” in the description of the numerical range represents a range from a to b unless otherwise specified.
In the present specification, the notation (meth) acrylic represents a concept including both acrylic and methacrylic.

  In the notation of a group (atomic group) in this specification, the notation which does not describe substitution or non-substitution includes both those having no substituent and those having a substituent. For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

In this specification, unless otherwise specified, the term “packaging body” is used to include both the packaging body itself (one in which an article is not packaged) and one in which some article is packaged.
In this specification, the diameter, shape, aspect ratio, and the like of various particles represent, in principle, primary particles, that is, the smallest particles that can exist alone.

<Manufacturing method of package>
The manufacturing method of the package of this embodiment is as follows:
Using an ink composition containing a component that irreversibly develops color by laser irradiation, a preparation step for obtaining a corrugated cardboard sheet equipped with a laser coloring layer;
An assembly process for assembling a cardboard box using cardboard sheets;
And a laser image forming step of forming an image by irradiating the laser coloring layer with laser light.

More specifically, the manufacturing method of the package of the present embodiment can be exemplified by the following first embodiment (including modifications) and second embodiment. However, the present invention is not limited to these embodiments. Especially the manufacturing method of the package of this embodiment is not limited only to the aspect performed according to the order of the process demonstrated by each embodiment.
Each embodiment will be described below.

(First embodiment)
FIG. 1A is a flowchart for explaining the manufacturing method of the package according to the first embodiment.
The manufacturing method of the package of the first embodiment is as follows:
A preparatory step (preparation step S1) for obtaining a corrugated cardboard sheet provided with a laser color developing layer using an ink composition containing a component that irreversibly develops color by laser irradiation;
An assembling process (assembling process S2) for assembling a cardboard box using a corrugated cardboard sheet;
A packaging process for packaging articles using a cardboard box (packaging process S3), and a laser image forming process for irradiating the laser coloring layer with laser light (laser image forming process S4)
These steps can be included. A package can be manufactured by these steps.
Here, as shown in FIG. 1B, the preparation step S1 can include a corrugated cardboard preparation step S11 and a laser color forming layer forming step S12 on the corrugated cardboard sheet.
Each of these steps will be described below.

・ Preparation process S1
The preparation step S1 includes a cardboard sheet preparation step S11 and a laser color forming layer forming step S12 on the cardboard sheet.

In the cardboard sheet preparation step S11, an appropriate cardboard sheet is prepared.
The corrugated cardboard sheet is a sheet-like sheet in which liners are pasted on both sides of a corrugated core using an adhesive such as starch paste or polyvinyl alcohol (PVA).

  The form of the cardboard sheet is not particularly limited as long as it can be finally assembled into a cardboard box. That is, the type of the raw material pulp of the liner and the core (whether it is wood pulp or pulp obtained from waste paper, etc.), the thickness, weight, size, etc. of the cardboard sheet are not particularly limited, and are commercially available products. Etc. can be used as appropriate.

  For example, a corrugated cardboard sheet has a classification called “flute”, but it is A flute, B flute, C flute, D flute, E flute, F flute, G flute, W flute, 2 layer AAA stage, 3 layer AAA stage. Any corrugated cardboard sheet may be used.

The color of the surface of the corrugated board sheet is not particularly limited as long as an image by laser irradiation can be recognized. The surface color is typically brown or white. In addition, as a method of making the surface color white, there is a method of printing white ink in advance on a brown corrugated cardboard sheet in addition to using a white liner.
By making the surface color white, it is expected to improve the clarity of laser coloring.

  Various treatments may be applied to part or all of the liner on the surface of the cardboard sheet. For example, a layer for easily forming the laser coloring layer, a layer for improving adhesion (anchor coat layer) are provided, or a pretreatment for preventing the laser coloring layer from being peeled off is performed. Or you may.

  In the laser color forming layer forming step S12 on the corrugated cardboard sheet, a laser color developing layer (laser) is formed on at least a part of the surface of the corrugated cardboard sheet prepared above by using an ink composition containing a component that irreversibly develops color by laser irradiation. A layer containing a component that irreversibly develops color upon irradiation).

  The ink composition used for forming the laser coloring layer is not particularly limited as long as it contains a component that irreversibly develops color by laser irradiation, but is preferably a specific ink composition described later.

The specific method for forming the laser coloring layer is not particularly limited. However, for reasons such as mass productivity and ease of forming the laser coloring layer in a desired region of the cardboard sheet, the following (Method 1), It is preferable that the method is at least one of (Method 2) and (Method 3). A plurality of these methods may be performed. Further, for the purpose of thickening the laser coloring layer, any of these methods may be performed twice or more on the same corrugated cardboard sheet.
(Method 1) A method of forming a laser color forming layer by rotating a blanket cylinder on which an ink composition is adhered and contacting the blanket cylinder with a cardboard sheet or a liner for a cardboard sheet.
(Method 2) A method of forming a laser coloring layer by flexographic printing.
(Method 3) A method of forming a laser coloring layer by gravure printing.
Hereinafter, these will be described in more detail.

(Method 1) is performed by, for example, an apparatus having a cross-sectional view schematically shown in FIG.
This apparatus includes a plate cylinder 13, an ink supply device 12 that supplies the ink composition 2 to the plate cylinder 13, a water supply device 11 that supplies dampening water (not shown) to the surface of the plate cylinder 13, and the plate cylinder 13. There are provided a blanket cylinder 14 which is arranged to face and the ink composition 2 adhered to the plate cylinder 13 is pressed onto the plate cylinder 13 and transferred to the surface, and an impression cylinder 15 arranged to face the blanket cylinder 14. ing.
The plate cylinder 13, the blanket cylinder 14, and the impression cylinder 15 are configured to rotate in directions indicated by arrows in the drawing.

As one aspect, the plate cylinder 13 has a part of the surface thereof that is oleophilic and the other area is hydrophilic, so that the ink composition 2 selectively adheres to the oleophilic area. Yes. As a means for providing the lipophilic / hydrophilic region, a known PS plate (Pre-Sensitized Plate) technique can be applied.
The surface of the blanket cylinder 14 is typically made of a rubber material so that the ink composition 2 attached to the plate cylinder 13 is transferred.

  The cardboard sheet 1 is sandwiched between the impression cylinder 15 and the blanket cylinder 14. The sandwiched cardboard sheet 1 is conveyed from the left to the right in FIG. 3 by the force of rotation of the impression cylinder 15 and the blanket cylinder 14 (indicated by arrows in the figure). Then, the ink composition 2 transferred to the surface of the blanket cylinder 14 is transferred to the surface of the cardboard sheet 1. With this series of flows, a laser coloring layer is formed on the surface of the cardboard sheet 1.

The linear velocity of rotation of the blanket cylinder 14 is preferably 40 to 350 m / min, more preferably 100 to 300 m / min, and further preferably 150 to 300 m / min. By setting it as this numerical value range, the adhesiveness with respect to the corrugated-cardboard sheet 1 of the ink composition 2 and mass-productivity can be made compatible. In particular, when a laser color forming layer is formed from a specific ink composition described later, an effect of increasing the abrasion resistance of the laser color developing layer can be expected.
In principle, the higher the linear velocity, the higher the productivity. However, the upper limit value of the linear velocity is usually about 400 m / min for practical use due to restrictions on the apparatus.

Here, the “linear velocity” of the rotation of the blanket cylinder 14 refers to the speed of the surface (side surface of the cylindrical blanket cylinder 14) when the blanket cylinder 14 rotates. The linear velocity can be obtained by calculating r · ω, where r is the radius of the cylindrical blanket cylinder 14 and ω is the angular velocity of rotation of the blanket cylinder 14. Further, since the angular velocity ω is in a relationship of ω = 2πn where n is the rotational speed (rotational speed) of the blanket cylinder 14, the linear speed can be obtained from the radius of the blanket cylinder 14 and the rotational speed (rotational speed). it can.
This linear velocity is substantially the same as the conveying speed of the corrugated cardboard sheet 1.

(Method 2) is performed by, for example, a cross-sectional apparatus (flexographic printing apparatus) schematically shown in FIG.
This apparatus includes a plate cylinder 13B, an anilox roll 22 for attaching the ink composition 2 to the plate cylinder 13B, a doctor blade 21 for removing excess ink composition 2 on the anilox roll 22, and a plate cylinder 13B. Is provided with an impression cylinder 15 </ b> B disposed opposite to the cylinder.
On the surface of the plate cylinder 13B, a convex portion to which the ink composition 2 is attached is provided by a polymer material having a certain flexibility and elasticity (flexographic printing is a kind of letterpress printing).
Each of the anilox roll 22, the plate cylinder 13B, and the impression cylinder 15B rotates in the direction indicated by the arrow in the drawing.

  The cardboard sheet 1 is sandwiched between the impression cylinder 15B and the plate cylinder 13B. The sandwiched corrugated cardboard sheet 1 is conveyed from left to right in FIG. 4 by the rotational force of the impression cylinder 15B and the plate cylinder 13B. Then, the ink composition 2 attached to the convex portion of the plate cylinder 13B is transferred to the surface of the cardboard sheet 1. With this series of flows, a laser coloring layer is formed on the surface of the cardboard sheet 1.

The linear velocity of rotation of the anilox roll 22 is preferably 40 to 350 m / min, more preferably 100 to 300 m / min, and further preferably 150 to 300 m / min. By setting it as this numerical range, the adhesiveness of the ink composition 2 with respect to the corrugated cardboard sheet 1 and mass productivity can be made compatible. In particular, when the ink composition 2 is a specific ink composition to be described later, an effect of increasing the abrasion resistance of the laser coloring layer can be expected.
In principle, the higher the linear velocity, the higher the productivity. However, the upper limit value of the linear velocity is usually about 400 m / min for practical use due to restrictions on the apparatus.

In order to form the laser coloring layer more uniformly by flexographic printing, for example, it is conceivable to appropriately select the anilox roll 22.
For example, the number of lines of the anilox roll 22 is preferably 100 to 500 lines / inch, more preferably 100 to 350 lines / inch, and further preferably 150 to 300 lines / inch. By selecting the anilox roll 22 having such a number of lines, it is expected that the thickness of the laser coloring layer can be increased, and as a result, a relatively high laser coloring density can be obtained.

Moreover, the lower limit of the cell capacity of the anilox roll 22 is preferably 5 cm ³ / m ² , more preferably 10 cm ³ / m ² , and even more preferably 12 cm ³ / m ² . By using the anilox roll 22 having a cell capacity equal to or greater than this lower limit, it is expected that the laser coloring layer can be appropriately thickened, and as a result, a relatively high laser coloring density can be obtained. The upper limit of the cell capacity is not particularly limited, but is preferably 40 cm ³ / m ² or less in consideration of the transferability of the ink composition 2 and prevention of clogging of the anilox roll 22.

  Furthermore, the cell shape of the anilox roll 22 includes a honeycomb shape, a diamond shape, a helical shape, and the like, and is not particularly limited, but a honeycomb shape is preferable.

When the anilox roll 22 having a line number of 250 lines / inch or more is used, a sufficient amount of the ink composition 2 may not adhere to the anilox roll 22. In this case, it is preferable to print the ink composition 2 twice or more at the same location on the cardboard sheet 1 using an apparatus in which two or more flexographic printing apparatuses of FIG.
In particular, when three or more (for example, 3 to 8) flexographic printing apparatuses of FIG. 4 are continuously installed, the ink composition 2 is printed using any two of the flexographic printing apparatuses, A laser coloring layer can be provided. The remaining flexographic printing apparatus can print a printing layer (such as an overprint varnish layer or an anchor layer) other than the laser coloring layer.

When the ink composition 2 is a specific ink composition to be described later, it is preferable to apply an anilox roll such as the above-mentioned number of lines, cell capacity, and cell shape.
The specific ink composition described below tends to be different in physical properties such as drying property and viscosity from an ink composition generally used in flexographic printing. Therefore, it is preferable to select an anilox roll according to the physical properties. By using an anilox roll that satisfies the above-mentioned number of lines, cell capacity, cell shape, etc., it is expected to reduce the clogging of a specific ink composition with an anilox roll and to improve the physical strength of the formed laser coloring layer. it can.

(Method 3) is performed, for example, by a cross-sectional apparatus (gravure printing apparatus) schematically shown in FIG.
This apparatus includes a plate cylinder 13C, an ink tray 31 for attaching the ink composition 2 to the plate cylinder 13C, a doctor blade 21C for removing excess ink composition 2 on the plate cylinder 13C, and the plate cylinder 13 Is provided with an impression cylinder 15 </ b> C arranged to face the surface.
The plate cylinder 13C and the impression cylinder 15C are configured to rotate in directions indicated by arrows in the drawing.
A concave portion is provided on the surface of the plate cylinder 13C. Ink composition 2 accumulates in the recess. The concave portion is typically formed by a method of engraving with a diamond needle on a copper plating applied on the plate cylinder 13C, or a method of laser exposure, development and corrosion.

  The cardboard sheet 1 is sandwiched between the impression cylinder 15C and the plate cylinder 13C. The sandwiched corrugated cardboard sheet 1 is conveyed from the left to the right in FIG. 5 by the force of rotation of the impression cylinder 15C and the plate cylinder 13C (indicated by arrows in the drawing). Then, the ink composition 2 accumulated in the concave portion of the plate cylinder 13 </ b> C is transferred to the surface of the cardboard sheet 1. With this series of flows, a laser coloring layer is formed on the surface of the cardboard sheet 1.

The linear speed of rotation of the plate cylinder 13C is preferably 40 to 350 m / min, more preferably 100 to 300 m / min, and further preferably 150 to 300 m / min. By setting it as this numerical range, the adhesiveness of the ink composition 2 with respect to the corrugated cardboard sheet 1 and mass productivity can be made compatible. In particular, when the ink composition 2 is a specific ink composition to be described later, an effect of increasing the abrasion resistance of the laser coloring layer can be expected.
In principle, the higher the linear velocity, the higher the productivity. However, due to restrictions on the apparatus, the upper limit of the linear velocity is usually about 400 m / min.

  In (Method 3), the depth of the concave portion provided in the plate cylinder 13C is preferably 10 to 70 μm, more preferably 20 to 60 μm, and further preferably 30 to 60 μm. The number of gravure lines is preferably 50 to 500 lines / inch, more preferably 80 to 350 lines / inch, and still more preferably 100 to 250 lines / inch.

  In particular, these conditions are preferably applied when the ink composition 2 is a specific ink composition described later. The specific ink composition described below tends to be different in physical properties such as drying property and viscosity from an ink composition generally used in gravure printing. Therefore, it is preferable to select conditions according to the physical properties. By selecting appropriate conditions, it is possible to reduce clogging and improve the physical strength of the formed laser coloring layer.

  The formation of the laser coloring layer is not limited to the method (Method 1), (Method 2) or (Method 3). For example, a bar coating method, a screen printing method, a pad printing method, a spray method, an ink jet method, and the like are also applicable.

  Moreover, when the ink composition 2 contains the polymeric compound and photoinitiator which are mentioned later, the process which hardens the ink composition 2 by applying an ultraviolet lamp etc. to the ink composition 2 mounted on the cardboard sheet | seat Is preferably provided.

  In the first embodiment, a laser coloring layer is formed on a substrate other than the cardboard sheet 1 (for example, paper having an adhesive layer on one side), and then the substrate on which the laser coloring layer is formed is used as the cardboard sheet. A laser coloring layer may be formed on the corrugated cardboard sheet by pasting or the like. However, from the viewpoint of production efficiency and the like, it is preferable to form the laser coloring layer by the method (Method 1), (Method 2) or (Method 3) described above.

  The thickness (average thickness) of the laser coloring layer is, for example, 1 to 30 μm, preferably 2 to 20 μm. By setting it within this range, it is considered that the color development at the time of laser irradiation can be sufficiently deepened while saving the amount of the ink composition 2 used. In addition, this thickness is the viscosity of the ink composition 2, the concentration, the amount used, and the conditions for forming the laser coloring layer (for example, adjusting the clamping force between the impression cylinder 15 and the blanket cylinder 14 in (Method 1) above). It can be changed by adjusting various other parameters.

As another aspect, the mass per unit area of the laser coloring layer is preferably ^{2 to} 14 g / m ² , more preferably 3 to 10 g / m ² . By setting it within this range, it is possible to expect the effect of making it difficult to peel off the laser coloring layer while sufficiently darkening the coloring at the time of laser irradiation.
It is preferable to control the concentration of the non-volatile component of the ink composition 2 and the amount of the ink composition 2 to be transferred so that the mass per unit area of the laser coloring layer is within this range.

  The area for forming the laser coloring layer may be appropriately adjusted as desired. For example, the laser coloring layer is provided so that the laser coloring layer is formed on 0.5 to 50%, preferably 2 to 30%, of the surface area of the finally obtained cardboard box.

・ Assembly process S2
In the assembly step S2, a cardboard box is assembled using a cardboard sheet. The method for assembling the cardboard box is not particularly limited. That is, the cardboard sheet is cut into an appropriate size, the cardboard sheet is partially cut, the cardboard sheet is creased, and the bottom part of the cardboard box is removed by appropriate means (adhesive tape, adhesive, glue, A cardboard box can be assembled by appropriately applying a known method such as forming with a stapler. Note that the “cardboard box” here typically means that the top surface of the box is open and the article can be accommodated inside and packaged.

・ Packaging process S3
It is preferable that the manufacturing method of the package body of 1st Embodiment includes packaging process S3 after assembly process S2. In the packaging step S3, an article is packaged using a cardboard box.

The specific method for packaging the article is not particularly limited. For example, a method of closing an opening of a cardboard box with various adhesive tapes after putting an article into the cardboard box, a method of closing an opening of the cardboard box with a stapler after putting the article into the cardboard box, etc. There is. An article placed inside the cardboard is not particularly limited.
In the packaging step S3, it is preferable that the above-mentioned adhesive tape does not overlap with the laser coloring layer or the above stapler does not damage the laser coloring layer.

・ Laser image forming step S4
In the laser image forming step S4, a desired image is formed on the cardboard by irradiating the laser coloring layer with laser light.
The type of laser that can be used is not particularly limited, and any laser can be used as long as the irreversibly colored component in the laser coloring layer develops color. For example, a CO ₂ laser, a fiber laser, a YAG laser, a semiconductor laser, or the like can be used. Further, the laser may be a laser array in which a plurality of laser light emitting elements are bundled. That is, in the laser image forming step S4, an image may be formed by irradiating the laser coloring layer with a plurality of laser beams at a time.

The intensity of the laser beam, the irradiation amount, and the like are not particularly limited. When the intensity of the laser beam is I (unit: W) and the scanning speed of the laser beam is v (unit: m / s), I / v is 1 Is preferably from 10 to 10, more preferably from 2 to 8.
By setting such a numerical range, it is possible to expect both improvement in throughput and color density.

  The image formed by laser irradiation is not particularly limited. Specifically, various trademarks / logo marks, advertising, shipping origin / destination, production location, lot number, expiration date and expiry date (especially when the packaged item is food), barcode, 2D Code (for example, QR code (registered trademark)) and the like can be mentioned. Of course, it is not limited to these characters and figures.

-Other process The manufacturing method of the package of 1st Embodiment may include arbitrary processes other than the above.
For example, a step of providing an additional layer such as a protective layer on the laser coloring layer may be included. Specific methods for providing this layer include a method of attaching or laminating a synthetic resin film on the laser coloring layer, and a method of providing an additional layer on the laser coloring layer by a printing method or a coating method. Examples of the material for providing the additional layer include “overcoat varnish” (overprint varnish) often used in the printing field and other well-known corrugated sheet surface treatment agents.

Such an additional layer is effective in increasing the abrasion resistance of the laser coloring layer. In the delivery / transport of corrugated cardboard (or a package in which an article is packaged with corrugated cardboard), “rubbing” between the corrugated cardboards is unavoidable, so it is desirable to protect the laser coloring layer with an additional layer.
Further, when the surface of the cardboard is too smooth, it may be inferior in handling properties, such as slipping and falling during delivery and transportation, and being difficult to grasp with bare hands or a robot arm. Therefore, a process for moderately deteriorating “slip” on the surface of the cardboard may be performed.
As another viewpoint, when corrugated cardboard is used for packaging for food use, a layer for enhancing resistance to condensation (water resistance) may be provided.

  The various additional layers described above are not formed only on the laser coloring layer, but may be formed, for example, on one surface or both surfaces of the cardboard sheet or on the entire outer surface of the cardboard box.

-Time between each process In the manufacturing method of the package of 1st Embodiment, after performing a certain process, the time until it performs the next process is not specifically limited. The same applies to a modified example to be described later and the second embodiment.
In particular, when a specific ink composition described later is used for forming the laser coloring layer, the deterioration (such as sensitivity reduction) of the laser coloring layer is extremely small. Thus, for example, after the preparatory step S1 or after assembling the cardboard box in the assembling step S2, it takes a long time (for example, 1 day to 3 years, more specifically 1) to form an image in the laser image forming step S4. Even if days to 1 year) have passed, there is basically no problem and a high-definition image can be formed on the cardboard box.

-Manufacturing method of a several package body By performing the manufacturing method of the packaging body of 1st Embodiment in multiple times etc., a several packaging body, ie, a 1st packaging body, and a 2nd packaging body can be obtained. In manufacturing such a plurality of packages, the image formed on the first package in the laser image forming step S4 and the image formed on the second package in the laser image forming step S4 are the same. May be different or different.

  From the viewpoint of making the most of the advantages of this embodiment, the image formed in the laser image forming step S4 on the first package and the image formed in the laser image forming step S4 on the second package are: Preferably they are different. Specifically, it is preferable that different logo marks are provided on a plurality of package bodies, different advertisements are provided on the plurality of package bodies, and different two-dimensional codes are provided on the plurality of package bodies.

As an effect of the first embodiment, it is possible to increase the speed and efficiency of printing when manufacturing a package.
Specifically, if a cardboard box having a laser coloring layer is manufactured and stored in advance by the above preparation process and assembly process, then the above-described laser image formation is performed according to the customer's order or the like. Thus, a packaging material having a desired image can be manufactured quickly and efficiently. In addition, by performing image formation with a laser, it is not necessary to prepare a separate material in the image forming process as in ink jet printing.

In particular, when a laser coloring layer is formed under the conditions such as the linear velocity described above with a specific ink composition described later, when a cardboard box equipped with a laser coloring layer is stored for a long period of time or in a hot and humid environment However, the laser coloring layer is not peeled off or deteriorated with time, and a sufficiently clear image can be obtained. (Some known printing materials are likely to deteriorate with time and do not develop color after a certain period of time or are sufficiently clear.) Many images are not obtained).
That is, according to the present embodiment, the method of “preparing and storing (storing) a cardboard box provided with a laser coloring layer in advance and then printing an image on the cardboard according to the order status of the article” is particularly applicable. A preferred cardboard box can be obtained.

(Modification 1 of the first embodiment)
FIG. 1C shows a modification (Modification 1) in which the part of the preparation step S1 is modified in the first embodiment.
The preparatory step S1 is different from the first embodiment described above in that the preparatory step S1 can include a liner preparatory step S13, a laser color forming layer forming step S14 on the liner, and a corrugated board sheet creating step S15. The assembly process S2, the packaging process S3, and the laser image forming process S4 are basically the same as those in the first embodiment.

  In the liner preparation step S13, a liner (liner for cardboard sheets) is prepared. The liner that can be used is not particularly limited. The type of liner or raw material pulp (whether it is wood pulp or pulp obtained from waste paper, etc.), the thickness, weight, size, etc. of the liner are not particularly limited, and commercially available products may be used as appropriate. it can. The color of the surface of the liner is not particularly limited as long as an image by laser irradiation can be recognized (similar to the case of the above-described cardboard sheet).

  Various treatments may be applied to part or all of the surface of the liner. For example, the laser coloring layer may be easily formed uniformly, a layer for improving adhesion may be provided, or a pretreatment may be performed to make the laser coloring layer difficult to peel off.

In the laser coloring layer forming step S14 on the liner, a laser coloring layer (irreversible by laser irradiation) is formed on at least a part of the surface of the liner prepared above using an ink composition containing a component that irreversibly develops color by laser irradiation. A layer containing a component that automatically develops color).
The ink composition that can be used and the specific method for forming the laser coloring layer are substantially the same as those in the first embodiment. That is, preferably, the laser coloring layer can be formed by the methods (Method 1), (Method 2), and (Method 3) described above.

In the corrugated cardboard creating step S15, a corrugated cardboard sheet can be produced using the liner on which the laser coloring layer is formed in the above step S14.
For example, a liner on which a laser coloring layer is formed (which becomes the outer surface of the box when the cardboard box is assembled) and a liner on which the laser coloring layer is not formed (which becomes the inner surface of the box when the cardboard box is assembled) The corrugated core is bonded to the corrugated core by using an adhesive such as starch paste or polyvinyl alcohol (PVA), whereby a corrugated cardboard sheet on which a laser coloring layer is formed can be produced.
The corrugated cardboard preparation step S15 can be performed using a series of machines called so-called corrugators that continuously produce corrugated cardboard sheets from a liner and a core.

  The laser coloring layer is formed by forming a laser coloring layer on a substrate other than the liner (for example, paper having an adhesive layer on one side), and then affixing the substrate on which the laser coloring layer is formed to the liner. May be formed. However, from the viewpoint of production efficiency and the like, it is preferable to directly form the laser coloring layer on the liner by the above-described (Method 1), (Method 2), or (Method 3).

As an effect of the modification 1 of 1st Embodiment, the effect similar to 1st Embodiment is mentioned.
In addition, by forming a laser coloring layer on the liner only in the liner instead of a relatively bulky corrugated sheet, the laser coloring layer can be formed in a large amount of speed more quickly. As a result, the laser coloring layer is provided. The effect of obtaining cardboard boxes in a larger amount and more efficiently can also be expected. This effect becomes more prominent by creating a cardboard sheet using the corrugator described above.

(Modification 2 of the first embodiment)
FIG. 1D shows another modified example (modified example 2) in which the part of the preparation step S1 is modified in the first embodiment.
The first embodiment described above is that the preparatory step S1 can include a corrugated sheet preparation step S11 and a laser color forming layer forming step S12 on the corrugated cardboard sheet, and an image forming step S16 that is not laser color developable. Different from form.
The assembly process S2, the packaging process S3, the laser image forming process S4 and the like are basically the same as those in the first embodiment. Further, the corrugated cardboard preparation step S11 and the laser color forming layer forming step S12 on the corrugated cardboard sheet are basically the same as those in the first embodiment.

  In the non-laser color forming step S16, typically, a desired image is formed on the cardboard sheet by a method other than laser irradiation. Specific examples of methods other than laser irradiation include, but are not limited to, offset printing methods, flexographic printing methods, gravure printing methods, screen printing methods, and ink jet printing methods.

  Further, the order of step S12 and step S16 may be reversed.

As an effect of the modification 2 of 1st Embodiment, the effect similar to 1st Embodiment is mentioned.
Further, an additional effect that the area required for laser irradiation can be reduced can be expected. In other words, images that are displayed in common on multiple cardboard boxes, such as logo marks and company names, can be reduced in the amount of laser irradiation required by forming them in advance in a cardboard box by means other than laser irradiation. it can. If the amount of laser irradiation can be reduced, it can be expected that the throughput of the laser image forming step S4 will be improved, and as a result, the manufacturing efficiency and cost of the package will be reduced. This effect is particularly remarkable when a plurality of packaging bodies are manufactured by performing the steps S1 to S4 a plurality of times.

(Second Embodiment)
FIG. 2 is a flowchart for explaining the manufacturing method of the package according to the second embodiment.
In FIG. 1A of 1st Embodiment, it is the same as that of 1st Embodiment except the order of packaging process S3 and laser image formation process S4 being reverse.
Specific aspects of each process (preparation process S1, assembly process S2, laser image forming process S4, and packaging process S3), processes that can be included in the preparation process S1, processes that may be included in addition to the illustrated processes, and the like This is basically the same as the first embodiment.
As the effect of the second embodiment, the same effect as that of the first embodiment can be mentioned.

<Ink composition>
Embodiments (including components) of the ink composition that are preferably used in the preparation steps of the first to fourth embodiments will be described. In addition, although this ink composition is preferably used for the purpose of producing the package of the present invention, it can also be used for other purposes.

(Component that irreversibly develops color by laser irradiation)
The ink composition of the present embodiment includes a component that irreversibly develops color by laser irradiation.
Here, the phrase “coloring irreversibly” means that the color once generated cannot be erased and recolored. Although it may be possible to change the color to another color, it is not possible to revert back to the originally generated color after returning to an uncolored state or to the original color. However, the phrase “coloring irreversibly” does not exclude the possibility of gradual coloration in everyday environments such as exposure to sunlight.
In the following description, a component that irreversibly develops color by laser irradiation is also simply referred to as “laser coloring component”.

  In the ink composition of the present embodiment, the laser coloring component includes (i) particles of an inorganic metal oxyanion compound, and / or (ii) particles of a compound represented by the color former and the general formula (I) described later. It is a combination. These will be specifically described.

(I) Particles of inorganic metal oxyanion compound Examples of the inorganic metal oxyanion compound include compounds containing transition metal oxyanions such as molybdate, tungstate, vanadate and chromate (salts of transition metal oxyacids). Etc.) can be used. Among these, compounds containing molybdenum oxyanions (such as molybdate) are preferable. Examples of the molybdenum oxyanion include heptamolybdate anion (Mo ₇ O ₂₄ ²⁻ ) and octamolybdate anion (Mo ₈ O ₂₆ ⁴⁻ ).

Examples of the counter cation of the inorganic metal oxyanion include alkali metal cations, alkaline earth metal cations, onium cations and the like. The counter cation is preferably a protonated primary amine, a protonated secondary amine, a protonated tertiary amine, an unsubstituted ammonium cation (NH ₄ ⁺ ), or the like. Among these, an unsubstituted ammonium cation (NH ₄ ⁺ ) is more preferable.

Particularly preferred as the inorganic metal oxyanion compound is ammonium molybdate, and particularly preferred is ammonium octamolybdate ((NH ₄ ) ₄ .Mo ₈ O ₂₆ ).

The median diameter (D _50A ) of the inorganic metal oxyanion compound particles is preferably 0.2 to 3 μm, more preferably 0.5 to 2 μm.
Here, when the particles of the inorganic metal oxyanion compound are commercial products and the median diameter is described in catalogs or specifications, the described value is the median diameter. Otherwise, the median diameter can be determined based on the measurement data with a laser diffraction particle size measuring device (for example, a laser diffraction particle size measuring device SALD3000J manufactured by Shimadzu Corporation).

The particles of the inorganic metal oxyanion compound are irreversibly colored when irradiated with laser light due to a change in oxidation state or the like.

(Ii) Combination of color former and compound particles represented by general formula (I) As the color former here, for example, a compound known as a leuco dye can be used. There are no particular restrictions on the leuco dyes that can be used, and known phthalide, fluoran, triarylmethane, benzoxazine, quinazoline, spiropyran, quinone, thiazine or oxazine leuco dyes can be used. .

  More specific examples of the color former (leuco dye) include compounds described in paragraph 0021 of JP-A-2015-193232, compounds described in paragraphs 0047 to 0056 of Japanese Patent No. 5914235, and the like.

The compound represented by formula (I) will be described.
The compound represented by the general formula (I) generates heat and melts by laser irradiation. It is considered that the color former develops color when a part of the melt reacts and interacts with the color former (leuco dye).

In general formula (I),
X is a silicon atom or a boron atom,
E and F are each independently a divalent organic group,
R ¹ and R ² are each independently a monovalent organic group,
When X is a silicon atom, (i) o is 1 and p is 0 and R ¹ is a monovalent organic group or (ii) o is 1 and p is 1 , R ¹ and R ² are linked together to form a ring structure;
When X is a boron atom, o is 0, p is 0,
R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom or a monovalent organic group, and two of these may be linked together to form a ring structure;
n is 1 or 2.

A preferred embodiment of the compound represented by formula (I) will be described.
X is preferably a boron atom.
The divalent organic group of E preferably forms a 5-membered ring or a 6-membered ring together with two O atoms to which E is bonded and X.
Specific examples of the divalent organic group for E include an alkylene group (preferably having 1 to 4 carbon atoms), a carbonyl group, an arylene group (such as a phenylene group), an ester group, and a group in which these groups are linked. .

  A preferred embodiment of the divalent organic group of F is the same as E described above.

  The divalent organic group of E and F is preferably any one of a to h shown below.

In the above a to h, R ⁶ and R ⁷ are a hydrogen atom, an alkyl group (preferably having 1 to 4 carbon atoms), an alkoxy group (preferably having 1 to 4 carbon atoms), a halogen atom, an amino group, or a carboxy group. .

Examples of the monovalent organic group for R ¹ and R ² include an alkyl group (preferably having 1 to 4 carbon atoms), an aryl group (preferably having 6 to 10 carbon atoms), and an aralkyl group (preferably having 7 to 11 carbon atoms). ) And the like.

Examples of the monovalent organic group for R ³ , R ⁴ and R ⁵ include an alkyl group (preferably having 1 to 12 carbon atoms), a hydroxyalkyl group (preferably having 1 to 6 carbon atoms), an aryl group (such as a phenyl group), Examples include aralkyl groups (preferably having 7 to 11 carbon atoms), arylsulfonyl groups (preferably having 6 to 10 carbon atoms), and the like. Among these, an alkyl group or a hydroxyalkyl group is preferable, and an alkyl group is more preferable.
These organic groups may be further substituted with a substituent such as an alkyl group or a halogen atom.
Two of R ³ , R ⁴ and R ⁵ may be linked to each other to form a ring structure. Examples of the ring structure in this case include a morpholine ring and a piperidine ring.

Specific examples of the compound represented by the general formula (I) include compounds listed in paragraphs 0027 and 0039 of Japanese Patent No. 5914235.
Moreover, about the ratio of a color former and the compound represented by general formula (I), the compound represented by general formula (I) is 0.1-10 mass parts normally with respect to 1 mass part of color formers, Preferably it is 0.2-7 mass parts, More preferably, it is 0.5-5 mass parts.

The amount of the component that irreversibly develops color by laser irradiation in the ink composition is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and still more preferably 30 to 30%, based on the total amount of the ink composition. It is 75 mass%, Most preferably, it is 35-70 mass%.
Further, when the total amount of the non-volatile components of the ink composition is used as a reference, the amount of the component that irreversibly develops color by laser irradiation is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 40%. It is -65 mass%.

When a sufficient amount of a component that irreversibly develops color by laser irradiation is contained in the ink composition, a clearer and darker image can be obtained.
In addition, when the component which irreversibly develops color by laser irradiation is a combination of the above-mentioned (ii) color former and the compound represented by the general formula (I), the color former and the general formula (I) are represented. The total amount (sum) of the compounds is preferably in the above numerical range.

(Pigment particles)
The ink composition of the present embodiment preferably contains pigment particles. The pigment particles here are components different from the combination of (i) particles of the inorganic metal oxyanion compound and (ii) particles of the color former and the compound represented by the following general formula (I). is there.

The pigment particles that can be used are not particularly limited. It is appropriately selected for the purpose of increasing the contrast of laser color development or matching the color of the laser color development layer with the color of the corrugated cardboard surface.
As one aspect, the pigment particles are preferably white pigment particles. Examples of white pigment particles include titanium dioxide particles, silica particles, calcium carbonate particles, zinc oxide particles, and talc particles.

  The white pigment particles preferably contain titanium dioxide from the viewpoint of availability. In particular, the purity (content) of rutile titanium dioxide in the total amount of white pigment particles is preferably 85% by mass or more, and more preferably 90% by mass or more.

There are several crystal forms of titanium dioxide. Crystalline type titanium dioxide other than rutile type may be slightly chemically unstable or may have catalytic ability to decompose other components in the ink composition. Therefore, the pigment particles are preferably composed of rutile-type titanium dioxide with the above purity. With this configuration, even if there is a long time between the assembly process and the laser image forming process, it is possible to further prevent the laser coloring layer from being deteriorated and the coloring density to be lowered. There were many cases where the color density dropped due to the above).
As a method for obtaining high-purity rutile titanium dioxide, for example, there is a method of changing the crystal type by heat-treating titanium dioxide particles containing other crystal types at a high temperature of 700 ° C. or higher.

The median diameter (D _50B ) of the pigment particles is preferably 0.1 to 0.8 μm, more preferably 0.2 to 0.7 μm. Here, D _50B is a written value such as a catalog or a specification, or a measured value by a laser diffraction particle size measuring device, as in D _50A .
The shape of the pigment particles is preferably approximately spherical or approximately elliptical.

The aspect ratio of the pigment particles expressed by the ratio of the major axis L to the minor axis S (L / S) is preferably 1 to 5, more preferably 1 to 3. By setting it within this range, the surface of the laser coloring layer can be made smoother and the contrast of laser coloring can be further increased.
Here, when the pigment particles are commercial products and the aspect ratio is described in catalogs or specifications, the described value is taken as the aspect ratio. Otherwise, the aspect ratio is the average of the aspect ratios of 50 arbitrary particles when white pigment particles are photographed with a scanning electron microscope (SEM).

  The amount of pigment particles in the ink composition is preferably 3 to 30% by mass, more preferably 5 to 20% by mass, based on the total amount of nonvolatile components in the ink composition.

In order to obtain high contrast and dark color development by laser irradiation, the ratio of the laser coloring component and the particle size of the pigment particles is one of the important factors. For example, when the laser coloring component is a particle of the aforementioned inorganic metal oxyanion compound, D _50A / D _50B is, for example, 0.25 to 30, preferably 1 to 20, more preferably 1.5 to 10, and particularly preferably. Is 1.5-8. In other words, it is preferable that the median diameter of the inorganic metal oxyanion compound particles is appropriately larger than the median diameter of the pigment particles.

  With the above configuration, pigment particles can enter the “interstices” of the particles of the inorganic metal oxyanion compound having a relatively large particle size. Then, the amount of pigment particles can be increased while maintaining the amount (concentration) of the inorganic metal oxyanion compound particles. That is, since the amount of the pigment particles can be increased while maintaining the color density (correlation with the amount of the inorganic metal oxyanion compound), the effect of the pigment particles can be sufficiently obtained. For this reason, an image with higher contrast can be obtained by laser irradiation.

(Dispersion treatment of particles, dispersant)
In the ink composition of the present embodiment, each of the particles (particles and pigment particles in the laser coloring component) may be subjected to a dispersion treatment with a dispersant or the like.
The dispersant is appropriately applied from known ones, but a random copolymer or block copolymer containing a pigment-affinity structure (for example, amine, ester, alcohol and carboxylic acid, and / or a salt structure thereof). Is mentioned. Commercially available products include EFKA (registered trademark) 4340 available from BASF SE, DISPERBYK (registered trademark) 2100 available from Byk-Chemie GmbH, and SOLPERSE (registered trademark) 39000 available from The Lubrizol Corporation. .
A known surfactant can also be applied. Examples of the surfactant include a low molecular surfactant, a high molecular surfactant, a nonionic surfactant, a cationic surfactant, and an anionic surfactant.

(resin)
The ink composition of the present embodiment preferably contains a resin. By including the resin, the ink composition has an appropriate viscosity, and the ink composition can be easily transferred to the corrugated cardboard sheet or the liner. Moreover, the effect that the dispersion | distribution of each particle | grain mentioned above is accelerated | stimulated or sedimentation is suppressed can also be expected.

  The resin can be used without particular limitation as long as it is used in the field of ink and paint. For example, phenol resin, (meth) acrylic resin, polyester resin, alkyd resin, polyamide resin, epoxy resin, nitrocellulose resin, rosin modified resin, maleic acid resin, urethane resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride vinyl acetate A copolymer etc. are mentioned. These may be used alone or in combination of two or more.

  When two or more kinds of resins are used in combination, the combination preferably includes a urethane resin and a vinyl chloride resin, a urethane resin and a vinyl acetate resin, a urethane resin and a vinyl chloride vinyl acetate copolymer, and the like.

Although the weight average molecular weight of resin is not specifically limited, For example, it is 3000-100000, Preferably it is 5000-50000, More preferably, it is 5000-20000. By setting it as this range, an ink composition can be made moderate viscosity.
The degree of dispersion of the resin (weight average molecular weight / number average molecular weight) is not particularly limited, but is, for example, 1 to 5, preferably 1.2 to 4.
These values are obtained, for example, by GPC (Gel Permeation Chromatography) measurement when polystyrene is used as a standard substance.

Although the glass transition temperature of resin is not specifically limited, For example, it is -50-150 degreeC, Preferably it is -40-100 degreeC, More preferably, it is -15-50 degreeC. By setting it as this range, the fluidity | liquidity of an ink composition can be made appropriate.
In addition, the glass transition temperature of resin can be measured based on JIS-K7121 with a differential scanning calorimeter (DSC).

  The amount of the resin in the ink composition is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, based on the total amount of nonvolatile components in the ink composition.

(solvent)
The ink composition of this embodiment preferably contains a solvent.
Solvents that can be used are broadly classified into water, petroleum-based solvents, vegetable oils and the like. These solvents may be used in combination as long as they are not separated in the composition.

As an example of the petroleum solvent, a hydrocarbon having 6 to 20 carbon atoms is preferably used. Specifically, paraffinic solvents such as n-pentane, isopentane, n-hexane, 2-methylpentane, n-heptane, n-octane, and trimethylpentane, and naphthenes such as cyclohexane, cyclohexylmethane, octadecylcyclohexane, and methylisopropylcyclohexane. Solvents, ester solvents such as ethyl acetate and butyl acetate, alcohol solvents such as isopropyl alcohol and n-butanol, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, AF solvent 4 manufactured by JX Nippon Oil & Energy Corporation AF solvent No. 5, AF solvent No. 6, AF solvent No. 7 and the like can be mentioned.
Examples of vegetable oils include soybean oil, linseed oil, tung oil, palm oil, coconut oil, rice bran oil and the like.

  The amount of the solvent in the ink composition is preferably 5 to 70% by mass and more preferably 10 to 60% by mass in all the components of the ink composition.

(Polymerizable compound and photopolymerization initiator)
The ink composition of the present embodiment may contain a polymerizable compound and a photopolymerization initiator.
In this case, the ink composition typically has a property of being cured (dried) by light such as ultraviolet rays.

As the polymerizable compound, a compound having an ethylenic double bond can be used. More specifically, known (meth) acrylic monomers and / or (meth) acrylic oligomers can be used.
Only 1 type may be used for a polymeric compound and it may use 2 or more types together.

Specific examples of the polymerizable compound include the following.
Monofunctional (meth) acrylate monomers such as 2-ethylhexyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, and (meth) acryloylmorpholine.

  Ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate (n = 2 to 20), propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate (n = 2 to 20), alkane (carbon number) 4-12) Glycol di (meth) acrylate, alkane (4 to 12 carbon atoms) glycol ethylene oxide adduct (2 to 20 mol) di (meth) acrylate, alkane (4 to 12 carbon atoms) glycol propylene oxide adduct ( 2-20 mol) di (meth) acrylate, hydroxypivalyl hydroxypivalate di (meth) acrylate, tricyclodecane dimethylol di (meth) acrylate, bisphenol A ethylene oxide adduct (2-20 mol) di (meth) Acrylate Hydrogenated bisphenol A di (meth) acrylate, hydrogenated bisphenol A ethylene oxide adduct (2-20 mol) di (meth) difunctional (meth) acrylate monomers such as acrylates.

  Glycerin tri (meth) acrylate, glycerin ethylene oxide adduct (3 to 30 mol) tri (meth) acrylate, glycerin propylene oxide adduct (3 to 30 mol) tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, Trifunctional (meth) acrylate monomers such as trimethylolpropane ethylene oxide adduct (3 to 30 mol) tri (meth) acrylate and trimethylolpropane propylene oxide adduct (3 to 30 mol) tri (meth) acrylate.

  Pentaerythritol tetra (meth) acrylate, pentaerythritol ethylene oxide adduct (4-40 mol) tetra (meth) acrylate, pentaerythritol propylene oxide adduct (4-40 mol) tetra (meth) acrylate, diglycerin tetra (meth) Acrylate, pentaerythritol ethylene oxide adduct (4-40 mol) tetra (meth) acrylate, pentaerythritol propylene oxide adduct (4-40 mol) tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, ditrimethylolpropane Ethylene oxide adduct (4 to 40 mol) tetra (meth) acrylate, ditrimethylolpropane propylene oxide adduct (4 to 40 mol) tetra (meth) Tetrafunctional vinyl compounds such as acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol ethylene oxide adduct (6 to 60 mol) hexa (meth) acrylate, dipentaerythritol propylene oxide adduct (6 to 60 mol) hexa A tetrafunctional or higher polyfunctional acrylate monomer such as (meth) acrylate.

  The amount of the polymerizable compound in the ink composition is preferably 5 to 80% by mass, more preferably 10 to 60% by mass, and still more preferably 15 to 50% by mass in all the components of the ink composition.

Known photopolymerization initiators can be appropriately used. Two or more photopolymerization initiators may be used in combination.
Specific examples of the photopolymerization initiator include α-hydroxyketone photoinitiator, α-aminoketone photoinitiator, bisacylphosphine photoinitiator, monoacylphosphine oxide, bisacylphosphine oxide, such as 2,4,6- Trimethylbenzoylbiphenylphosphine oxide, ethyl-2,4,6-trimethylbenzoylphenylphosphinate, mono- and bis-acylphosphine photoinitiators, benzyldimethyl-ketal photoinitiators, oligo [2-hydroxy-2-methyl-1 -[4- (1-methylvinyl) phenyl] propanone] and the like. These are manufactured by BASF and sold under the name IRGACURE® series and the like. Of course, photopolymerization initiators other than these can also be used.

  The amount of the photopolymerization initiator in the ink composition is preferably 1 to 15% by mass, more preferably 2 to 13% by mass, and further preferably 3 to 10% by mass in all the components of the ink composition.

(Other ingredients: Various additives)
The ink composition of the present embodiment may contain various additives such as a leveling agent, a dispersion aid, a rheology modifier, an antifoaming agent, a metal soap, and an antioxidant in addition to the above-described components.

As the rheology modifier, for example, the following can be used.
Compounds having two or more amide bonds in one molecule: Disparon series manufactured by Enomoto Kasei Co., Ltd.
Compounds having two or more urea bonds in one molecule: products of BYK-Japan, BYK-410, BYK-E410, BYK-415, BYK-420, BYK-E420, BYK-D410, BYK-430 and the like.
Fatty acid amide: Nippon Kasei Co., Ltd. product, diamond series, etc.
Extender pigments: bentonite, silica, clay, white carbon, precipitated barium sulfate, aluminum silicate, kaolin and the like.

  Associative rheology modifier: acrylic swelling associative rheology modifier and / or urethane associative rheology modifier, specifically, RM-5, TT-615, TT-935, RM-8, RM-825, RM -1020, SCT-275, RM-2020, RM-SW, RM-2020NPR, RM-R, RM-12W, DR-1, DR-72, DR-300, RM-7, RM-50000, RM-60000 , RM-845, RM-995 (Rohm and Haas), Adecanol VF, UH-462, UH-752, UH-140S, UH-420, UH-438, UH-472, UH-450, UH -540, UH-550, UH-541VF, UH-526, UH-530 (manufactured by ADEKA), Cognis 3220, RheovisP 1332, PU1190, PU1191, PU1214, PU1215, PU1250, PU1251, PU1256, PU1270, PU1280, PU1291, PU1331 (manufactured by BASF), RHEOLATE266, 288, 244, 255, 278 (manufactured by RHEOX), SN thickener A-803, A-804, A-807, A-812, A-814 (manufactured by San Nopco) and the like.

Polymeric rheology modifier: alkali-soluble polymer having a weight average molecular weight in the range of 100,000 to 3 million and / or rheology modifier of polyethylene glycol, specifically, Primal ASE-60, TT-615, ASE-75, ASE-108, RM-5, ASE-95NP (manufactured by Rohm and Haas), Alcox R-1000, R-400, R-150, E-60, E-45, E-30 , E-300, E-240, E-160, E-100, E-75 (manufactured by Meisei Chemical Co., Ltd.), Rheovis AS1125, AS1130, AS1188, AS1956 (manufactured by BASF), Aron A-20L, A-7100, A -10H, A-7255, A-7185, A-7195, A-7075, A-7055, B-300K, B-500 (Toa Narusha, Ltd.), and the like.
By using the rheology modifier, the viscosity of the ink composition described later can be appropriately adjusted.

  The content of various additives in the ink composition is preferably 0.01 to 5% by mass, more preferably 0.1 to 5% by mass in all the components of the ink composition.

(Physical properties of ink composition)
As for the viscosity of the ink composition of the present embodiment, the viscosity η ₁ measured at 25 ° C. and a shear rate of 1 s ⁻¹ is preferably 300 Pa · s or less. More specifically, η ₁ is more preferably 0.05 to 300 Pa · s, further preferably 0.05 to 100 Pa · s, and particularly preferably 0.05 to 10 Pa · s.

As another aspect, the ink composition, when formed into a ₂ viscosity eta at a shear rate 100s ^-1 at 25 ° C., the value of eta _{1 /} eta ₂ is preferably at 2 or more, 5 or more More preferably, it is 10 or more.
Although there is no particular upper limit to the value of η ₁ / η ₂ , from a practical viewpoint, η ₁ / η ₂ is preferably 1000 or less, more preferably 500 or less, and even more preferably 300 or less.
Here, a rotary rheometer can be used for the measurement of η ₁ and η ₂ .

The values of η ₁ and η ₂ can be adjusted, for example, by carefully selecting the aforementioned resin or using an appropriate amount of the aforementioned rheology modifier.

  Here, the aspect of the ink composition that is preferably applied to each of the above-described (Method 1), (Method 2), or (Method 3) will be supplemented.

Embodiment of ink composition preferably applied to (Method 1):
An ink composition containing one or more of rosin-modified resins (such as rosin-modified phenol resins and rosin-modified epoxy resins), alkyd resins (such as linseed oil-modified alkyd resins), petroleum resins, and the like as resins.
-Ink compositions containing petroleum solvents (such as aliphatic petroleum solvents) and vegetable oils (such as soybean oil) as solvents. In particular, an ink composition comprising both a petroleum solvent and vegetable oil.

Embodiment of ink composition preferably applied to (Method 2):
-As the resin, an ink composition containing one or more of (meth) acrylic resin, urethane resin, polyamide resin, nitrocellulose resin, rosin-modified resin, etc. (especially when the solvent is aqueous, the resin is It is preferably any one of an alkali-soluble type, a colloidal dispersion type, and an emulsion type).
-An ink composition in which the main component is water and an alcohol solvent or glycol solvent is used in combination as necessary.

Embodiment of ink composition preferably applied to (Method 3):
An ink composition containing one or more of rosin-modified resin, nitrocellulose resin, polyamide resin, urethane resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride vinyl acetate copolymer, etc. (particularly urethane) A combination of a resin and a vinyl chloride / vinyl acetate copolymer is preferred).
An ink composition containing one or more of alcohol solvents, ketone solvents, ester solvents, hydrocarbon solvents and the like as a solvent.
An ink composition in which an alcohol solvent and water are used in combination as a solvent.

  In addition, the aspect of each said ink composition is a thing when it is not photocurable. When the ink composition is photocurable, typically, a part or all of the above-described resins and solvents are mixed with a polymerizable compound (such as a monofunctional or polyfunctional (meth) acrylate compound) and light. Replaced with a mixture of polymerization initiators.

(Method for producing ink composition)
The ink composition of the present embodiment can be obtained by appropriately mixing the above components with a mixer or the like. In mixing, it is particularly desirable to uniformly disperse the above-described particle components (laser coloring component and pigment particles) in the composition.
As a dispersion method, when the viscosity of the ink composition is relatively large, a method such as a three-roll mill method, a kneader method, or a flash method can be applied. Further, when the viscosity of the ink composition is relatively small, a method such as a media-type disperser method or a chip method can be applied. In addition, the preparation method of the ink composition is described in Chapter 4 of the book “Printing ink that can be used well” (Kenji Katayama, Nihon Printing Shimbun, published in July 1999).

  As mentioned above, although embodiment of this invention was described, these are illustrations of this invention and can employ | adopt various structures other than the above. Further, the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

  Embodiments of the present invention will be described in detail based on examples and reference examples. In addition, this invention is not limited to an Example.

<Example 1-1>
1. Preparation Step Using the apparatus of the cross-sectional view schematically shown in FIG. 3 and an ink composition (shown below), a laser coloring layer was formed on the surface of a liner for a cardboard sheet (weighed: 170 g / m).
Here, the linear velocity of rotation of the blanket cylinder was set to 50 m / min.

As the ink composition, the following materials were sufficiently mixed / kneaded. The value of η ₁ / η ₂ of this ink composition was 2 or more.
-Laser coloring component: ammonium octamolybdate particles, particle size ( _D50A ) 1.5 [mu] m 40 parts by mass-Pigment particles: titanium dioxide, particle size ( _D50B ) 0.5 [mu] m, substantially spherical (aspect ratio 1), rutile type Purity of 90% by mass 10 parts by mass Resin: 30 parts by mass of rosin-modified phenol resin Solvent: 10 parts by mass of n-hexane, 5 parts by mass of soybean oil, 3 parts by mass of linseed oil Additives: fatty acid amide, dispersant (interface) Activator system), antioxidant, etc. 2 parts in total

  The liner on which the laser coloring layer was formed was passed through a corrugator for producing cardboard. Then, a D flute corrugated cardboard sheet on which a laser coloring layer was formed was obtained.

2. Assembly process 1. The corrugated cardboard sheet with the laser coloring layer formed thereon was processed to produce a corrugated cardboard box with the bottom closed and the top opened.
This cardboard box was stored for 3 months in an environment (40 ° C., 80% RH) simulating a hot and humid warehouse.

3. Packaging process 2. The article was put in the cardboard box that was prepared and stored in Then, the opening of the upper surface was closed with an adhesive tape to obtain a package.

4). Laser image forming step 3. A barcode was drawn using a CO ₂ laser on the portion of the laser coloring layer of the package obtained in the above. As a result, an extremely clear and high contrast barcode can be drawn.

<Example 1-2>
In Example 1-1 above, As in Example 1-1, except that the linear velocity of rotation of the blanket cylinder in the preparation step was 200 m / min. ~ 4. Each process of was performed. Also in this case, the barcode could be drawn satisfactorily. The same was true when the linear velocity was 70 m / min, 150 m / min, and 300 m / min.
Further, even when the linear velocity was 30 m / min, a sufficiently visible barcode could be drawn. However, in this case, when storing the cardboard, a part of the laser coloring layer may fall off the cardboard due to rubbing between the cardboards.

<Example 1-3>
In Example 1-1 above, the ink composition was changed to the following composition, and Example 1-1 was used except that ultraviolet irradiation was performed immediately after the formation of the laser coloring layer on the corrugated cardboard sheet surface. Similarly 1. ~ 4. Each process of was performed. Also in this case, the barcode could be drawn satisfactorily.

-Laser coloring component: ammonium octamolybdate particles, particle size ( _D50A ) 1.5 [mu] m 40 parts by mass-Pigment particles: titanium dioxide, particle size ( _D50B ) 0.5 [mu] m, substantially spherical (aspect ratio 1), rutile type 10 mass parts of resin: 20 mass parts of resin: acrylate resin, photopolymerization initiator: 7 mass parts of 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one Compound: 20 parts by mass of dipentaerythritol hexaacrylate / Additive: Fatty acid amide, dispersant (surfactant), antioxidant, etc. 3 parts in total

<Example 2-1>
1. Preparation Step A laser color developing layer was formed on the surface of a corrugated cardboard sheet using a flexographic printing apparatus and an ink composition (shown below) in which two apparatuses having a cross-sectional view schematically shown in FIG. That is, the ink composition was continuously printed twice at the same location on one cardboard sheet to obtain a cardboard sheet on which a laser coloring layer was formed.
Here, the linear velocity of rotation of the anilox roll was set to 50 m / min. The number of wires of the anilox roll was 250 wires / inch, the cell volume was 12 cm ³ / m ² , and the cell shape was a honeycomb shape. The conditions for the anilox roll were the same in the two series of apparatuses.
As the corrugated cardboard sheet, a D flute sheet was used.

As the ink composition, the following materials were sufficiently mixed / dispersed. The value of η ₁ / η ₂ of this ink composition was 2 or more.
-Laser coloring component: ammonium octamolybdate particles, particle size (D _50A ) 1.5 µm 50 parts by mass-Pigment particles: titanium dioxide, particle size (D _50B ) 0.5 µm, substantially spherical (aspect ratio 1), rutile type Purity 90 mass% 5 mass parts / resin: PMMA (polymethyl methacrylate) emulsion resin 10 mass parts, styrene acrylic acid resin 10 mass parts / solvent: water 20 mass parts, 2-propanol (isopropyl alcohol) 1 mass part・ Additives: Polymer-type rheology modifier, antifoaming agent, etc.

2. Assembly process 1. The corrugated cardboard sheet with the laser coloring layer formed thereon was processed to produce a corrugated cardboard box with the bottom closed and the top opened.
This cardboard box was stored for 3 months in an environment (40 ° C., 80% RH) simulating a hot and humid warehouse.

3. Packaging process 2. The article was put in the cardboard box prepared and stored in (1), and then the opening on the upper surface was closed with an adhesive tape to obtain a package.

4). Laser image forming step 3. A barcode was drawn using a CO ₂ laser on the portion of the laser coloring layer of the package obtained in the above. As a result, an extremely clear and high contrast barcode can be drawn.

<Example 2-2>
In Example 2-1 above, As in Example 2-1, except that the linear velocity of rotation of the anilox roll in the preparation step was set to 200 m / min. ~ 4. Each process of was performed. Also in this case, the barcode could be drawn satisfactorily. The same was true when the linear velocity was 70 m / min, 150 m / min, and 300 m / min.
Further, even when the linear velocity was 30 m / min, a sufficiently visible barcode could be drawn. However, in this case, when storing the cardboard, a part of the laser coloring layer may fall off the cardboard due to rubbing between the cardboards.

<Example 2-3>
In Example 2-1, the laser coloring component (50 parts by mass of ammonium octamolybdate particles) in the ink composition was used as crystal violet lactone (3,3-bis (p-dimethylaminophenyl) -6-dimethyl- Aminophthalide) As in Example 2-1, except that 18 parts by mass and 32 parts by mass of boron compound particles represented by the following chemical formula were used. ~ 4. Each process of was performed. Also in this case, the barcode could be drawn satisfactorily.

<Example 3-1>
1. Preparation Step A laser color-developing layer was formed on the surface of the corrugated cardboard sheet using the apparatus (gravure printing apparatus) and the ink composition (shown below) shown schematically in FIG.
Here, the linear velocity of rotation of the plate cylinder was set to 50 m / min. Further, as the plate cylinder, a gravure roll produced by laser exposure, development and corrosion processes was used. The number of lines of this gravure roll was 150 lines / inch, and the plate depth (depth of the concave portion provided in the plate cylinder 13C) was 40 μm.
Further, as the corrugated cardboard sheet, the same one as in Example 2-1 was used.

As the ink composition, the following materials were sufficiently mixed / dispersed. The value of η ₁ / η ₂ of this ink composition was 2 or more.
-Laser coloring component: ammonium octamolybdate particles, particle size ( _D50A ) 1.5 [mu] m 20 parts by mass-Pigment particles: titanium dioxide, particle size ( _D50B ) 0.5 [mu] m, substantially spherical (aspect ratio 1), rutile type Purity 90 mass% 8 mass parts / resin: weight average molecular weight 10000-30000, urethane resin 15 mass parts with glass transition temperature around 10 ° C., vinyl chloride vinyl acetate copolymer 5 mass parts, solvent: methyl ethyl ketone 40 mass parts, acetic acid 5 parts by mass of ethyl, 5 parts by mass of 2-propanol (isopropyl alcohol)
・ Additives: Fatty acid amide, dispersant (surfactant), antioxidant, etc. 2 parts in total

2. Assembly process 1. The corrugated cardboard sheet with the laser coloring layer formed thereon was processed to produce a corrugated cardboard box with the bottom closed and the top opened.
This cardboard box was stored for 3 months in an environment (40 ° C., 80% RH) simulating a hot and humid warehouse.

3. Packaging process 2. The article was put in the cardboard box prepared and stored in (1), and then the opening on the upper surface was closed with an adhesive tape to obtain a package.

4). Laser image forming step 3. A barcode was drawn using a CO ₂ laser on the portion of the laser coloring layer of the package obtained in the above. As a result, an extremely clear and high contrast barcode can be drawn.
<Example 3-2>
In the above Example 3-1, 1. As in Example 3-1, except that the linear velocity of rotation of the plate cylinder in the preparation step was set to 200 m / min. ~ 4. Each process of was performed. Also in this case, the barcode could be drawn satisfactorily. The same was true when the linear velocity was 70 m / min, 150 m / min, and 300 m / min.
Further, even when the linear velocity was 30 m / min, a sufficiently visible barcode could be drawn. However, in this case, when storing the cardboard, a part of the laser coloring layer may fall off the cardboard due to rubbing between the cardboards.

<Reference example>
In Example 1-1, (1) instead of forming a laser coloring layer with an ink composition, a cardboard sheet was produced using a known thermal paper, and (2) a barcode was drawn by CO. _{As in} Example 1-1, except for two points that were performed by a thermal printer instead of _two lasers, 1. ~ 4. Each process of was performed. In this case, a practically sufficient density and definition barcode could not be drawn.

  From the above examples and reference examples, it was shown that according to the present invention, it is possible to speed up and increase the efficiency of printing on a package.

DESCRIPTION OF SYMBOLS 1 Corrugated cardboard sheet 2 Ink composition 11 Water supply apparatus 12 Ink supply apparatus 13, 13B, 13C Plate cylinder 14 Blanket cylinder 15, 15B, 15C Impression cylinder 21, 21C Doctor blade 22 Anilox roll 31 Ink tray S1 Preparatory process S2 Assembly process S3 Packaging step S4 Laser image forming step S11 Corrugated cardboard sheet preparing step S12 Laser coloring layer forming step S13 Liner preparing step S14 Laser coloring layer forming step S15 Corrugated cardboard forming step S16 Non-laser color forming step

Claims (28)

Using an ink composition containing a component that irreversibly develops color by laser irradiation, a preparation step for obtaining a corrugated cardboard sheet equipped with a laser coloring layer;
An assembly step of assembling a cardboard box using the cardboard sheet;
And a laser image forming step of forming an image by irradiating the laser coloring layer with laser light. It is a manufacturing method of the package according to claim 1,
The manufacturing method of a package body including the packaging process which packages an article | item using the said cardboard box after the said assembly process. It is a manufacturing method of the package according to claim 1 or 2,
The preparation step includes a step of forming a laser coloring layer by contacting the blanket cylinder with a corrugated cardboard sheet or a liner for corrugated sheet while rotating the blanket cylinder on which the ink composition is adhered,
The manufacturing method of the package body whose linear velocity of rotation of the said blanket cylinder is 40-350 m / min. It is a manufacturing method of the package according to claim 1 or 2,
The preparation step includes a step of forming a laser coloring layer by flexographic printing,
The manufacturing method of the package body whose linear velocity of rotation of the anilox roll of the said flexographic printing is 45-350 m / min. It is a manufacturing method of the package according to claim 1 or 2,
The preparation step includes a step of forming a laser coloring layer by gravure printing,
The manufacturing method of the package body whose linear velocity of rotation of the plate cylinder of the said gravure printing is 45-350 m / min. It is a manufacturing method of the packing object according to any one of claims 1 to 5,
The manufacturing method of the package body in which the said ink composition contains the particle | grains of an inorganic metal oxyanion compound. It is a manufacturing method of the packing object according to any one of claims 1 to 5,
A method for producing a package, wherein the ink composition comprises a color former and particles of a compound represented by the following general formula (I).

In general formula (I),
X is a silicon atom or a boron atom,
E and F are each independently a divalent organic group,
R ¹ and R ² are each independently a monovalent organic group,
When X is a silicon atom, (i) o is 1 and p is 0 and R ¹ is a monovalent organic group or (ii) o is 1 and p is 1 , R ¹ and R ² are linked together to form a ring structure;
When X is a boron atom, o is 0, p is 0,
R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom or a monovalent organic group, and two of these may be linked together to form a ring structure;
n is 1 or 2. It is a manufacturing method of the package according to claim 6 or 7,
The manufacturing method of the package body in which the said ink composition contains a pigment particle. It is a manufacturing method of the package according to claim 8,
The manufacturing method of the package body in which the said pigment particle contains titanium dioxide. It is a manufacturing method of the package according to claim 8 or 9,
The manufacturing method of the package body whose aspect-ratio represented by ratio (L / S) of the major axis L and the minor axis S of the said pigment particle is 1-5. It is a manufacturing method of the packing object given in any 1 paragraph of Claims 8-10,
The ink composition comprises particles of the inorganic metal oxyanion compound, the median diameter of the particles and D _50A,
When the median diameter of the pigment particles was D _50B,
The value of D _50A / _{D 50B} is 1.5 to 10, a manufacturing method of the package. It is a manufacturing method of the packing object according to any one of claims 1 to 11,
The viscosity of the ink composition at a shear rate of 1 s ⁻¹ at 25 ° C. is η ₁ ,
When the viscosity of the ink composition at a shear rate of 100 s ⁻¹ at 25 ° C. is η ₂ ,
The manufacturing method of a package body whose value of (eta) ₁ / (eta) ₂ is 2 or more. It is a manufacturing method of the packing object according to any one of claims 1 to 12,
The manufacturing method of the package body in which the said ink composition contains resin. It is a manufacturing method of the package according to claim 13,
The resin is phenol resin, (meth) acrylic resin, polyester resin, alkyd resin, polyamide resin, epoxy resin, nitrocellulose resin, rosin modified resin, maleic acid resin, urethane resin, vinyl chloride resin, vinyl acetate resin and vinyl chloride. The manufacturing method of a package body containing at least 1 sort (s) or 2 or more types chosen from the group which consists of a vinyl acetate copolymer. It is a manufacturing method of the package according to claim 13 or 14,
The manufacturing method of the package body whose content of the said resin is 20-80 mass% with respect to the whole non-volatile component of the said ink composition. It is a manufacturing method of the packing object according to any one of claims 1 to 15,
The manufacturing method of a package body in which the said ink composition contains a polymeric compound and a photoinitiator. It is a manufacturing method of the packing object according to any one of claims 1 to 16,
A method for producing a package, wherein the corrugated cardboard sheet provided with the laser coloring layer is provided with an image by means other than laser irradiation. A manufacturing method of a plurality of packaging bodies, wherein the first packaging body and the second packaging body are manufactured by the manufacturing method of the packaging body according to any one of claims 1 to 17,
A method for manufacturing a plurality of packages, wherein an image formed on the first package in the laser image forming step and an image formed on the second package in the laser image forming step are different from each other. An ink composition comprising a component that irreversibly develops color by laser irradiation,
An ink composition comprising a combination of particles of an inorganic metal oxyanion compound and / or a particle of a color former and a compound represented by the following general formula (I) as a component that irreversibly develops color by laser irradiation.

In general formula (I),
X is a silicon atom or a boron atom,
E and F are each independently a divalent organic group,
R ¹ and R ² are each independently a monovalent organic group,
When X is a silicon atom, (i) o is 1 and p is 0 and R ¹ is a monovalent organic group or (ii) o is 1 and p is 1 , R ¹ and R ² are linked together to form a ring structure;
When X is a boron atom, o is 0, p is 0,
R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom or a monovalent organic group, and two of these may be linked together to form a ring structure;
n is 1 or 2. The ink composition according to claim 19, wherein
An ink composition comprising pigment particles. The ink composition according to claim 20, wherein
An ink composition in which the pigment particles contain titanium dioxide. The ink composition according to claim 20 or 21,
An ink composition having an aspect ratio of 1 to 5 represented by a ratio (L / S) of major axis L to minor axis S of the pigment particles. The ink composition according to any one of claims 20 to 22, wherein
The ink composition comprises particles of the inorganic metal oxyanion compound, the median diameter of the particles and D _50A,
When the median diameter of the pigment particles was D _50B,
The value of D _50A / _{D 50B} is an ink composition is 1.5 to 10. The ink composition according to any one of claims 19 to 23,
The viscosity of the ink composition at a shear rate of 1 s ⁻¹ at 25 ° C. is η ₁ ,
When the viscosity of the ink composition at a shear rate of 100 s ⁻¹ at 25 ° C. is η ₂ ,
An ink composition having a value of η ₁ / η ₂ of 2 or more. 25. The ink composition according to any one of claims 19 to 24, wherein
An ink composition containing a resin. The ink composition according to claim 25, wherein
The resin is phenol resin, (meth) acrylic resin, polyester resin, alkyd resin, polyamide resin, epoxy resin, nitrocellulose resin, rosin modified resin, maleic acid resin, urethane resin, vinyl chloride resin, vinyl acetate resin and vinyl chloride. An ink composition comprising at least one or more selected from the group consisting of vinyl acetate copolymers. The ink composition according to claim 25 or 26,
The ink composition whose content of the said resin is 20-80 mass% with respect to the whole non-volatile component of the said ink composition. The ink composition according to any one of claims 19 to 27, wherein
An ink composition containing a polymerizable compound and a photopolymerization initiator.

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