JP2021035722A - Manufacturing method of package - Google Patents

Abstract

To print a clear character in a manufacture of a package including a printing step by laser marking.SOLUTION: A packaging material includes a substrate layer and a laser color-developing layer containing a component (X) configured to irreversibly develop a color by an irradiation of a laser beam. A manufacturing method of a package includes a printing step of irradiating the packaging material with a spot of a laser beam so as to print a character on the packaging material. As a font of a character to be printed, a font is used in which an acute angle portion, a three-forked portion and an intersection portion of lines with each other are not included, and the spot is moved along a line composing the font.SELECTED DRAWING: Figure 6

Description

The present invention relates to a method for producing a package. More specifically, the present invention relates to a method for manufacturing a package including a printing step of printing on a packaging material by a so-called laser marking technique.

In recent years, a technique for forming an image by irradiating a component that irreversibly develops color by irradiating a laser beam with a laser beam (laser marking technique) has been actively studied. In particular, there are many studies on laser marking on the packaging (packaging material) of goods.

There are various fields in which laser marking technology is expected to be applied, and for example, there is a field of food packaging. Where stricter food traceability is a trend in the world, there is a strong need to print the date of manufacture, expiration date, factory unique number, etc. by irreversible color development and tamper-proof laser marking. Exists.

Patent Document 1 is a document relating to "a method of laser marking a packaging film for packaging foods and the like". According to claim 1 of this document, in a method of laser marking a packaging film in which at least a surface layer and a sealing layer are laminated, a laser beam is applied to a white ink layer using a film and titanium oxide sandwiched between the films as a colorant. The marking characters are composed of the original characters and the characters that are diagonally shifted so that the lines look thicker when reading, and the laser beam re-irradiates the blackened part of the original characters. A method for laser marking a packaging film is described, which comprises using a font consisting of staggered characters.

Further, according to claim 2 of this document, in a method of laser marking a packaging film formed by laminating at least a surface layer and a sealing layer, a white ink layer using a film and titanium oxide sandwiched between the films as a colorant is used. Characters that are composed of so-called bag characters that are blackened by irradiating laser light and trace the outline of the characters that are displayed so that the marking characters are easy to read when reading, and that the laser light does not re-irradiate the blackened parts of the characters. A method for laser marking a packaging film, which comprises using a font consisting of the above, is described.

Japanese Unexamined Patent Publication No. 2013-146880

In laser marking, it is of course preferable that the printed characters are clear. Especially when laser marking is used for food packaging, it is preferable that the characters are clear because it is a general consumer who reads the printed characters. Needless to say, it is preferable that the characters are clear even in the packaging field other than food.

However, according to the knowledge of the present inventor, when characters are printed by conventional laser marking, the printing may be unclear, for example, "bleeding" may occur in the characters.

The present invention has been made based on such circumstances. That is, one of the objects of the present invention is to print clear characters in the manufacture of a package including a printing process by laser marking.

As a result of diligent studies, the present inventors have found that the above problems can be achieved by the inventions provided below.

According to the present invention, the following inventions are provided.

A printing process in which a spot of a laser beam is applied to a packaging material including a base material layer and a laser coloring layer containing a component (X) that irreversibly develops color by irradiation with the laser beam, and characters are printed on the packaging material. It is a manufacturing method of a package including
As the font of the characters to be printed, a font that does not include acute-angled parts, three-way junctions, and intersections of lines is used, and
A method of manufacturing a package in which the spots are moved along the lines that make up the font.

According to the present invention, clear characters can be printed in the manufacture of a package including a printing process by laser marking.

It schematically shows the manufacturing method of the package body of this embodiment. FIG. 1A schematically describes a process of printing a font of the capital letter “O” (O) of the alphabet in the manufacture of a package. FIG. 1B illustrates the stroke order of the capital letters “O” (O) in the alphabet. FIG. 2A is an example of the font of the number “4” in the method for manufacturing the package of the present embodiment. FIG. 2B is an example of the font of the number “4” in the conventional laser marking. FIG. 3A is an example of the font of the alphabet “E” in the method for manufacturing the package of the present embodiment. FIG. 3B is an example of the font of the alphabet “E” in the conventional laser marking. FIG. 4A is a diagram illustrating an example of the stroke order of the font of the Arabic numeral “5” in the method for manufacturing the package of the present embodiment. FIG. 4B is a diagram illustrating an example of the stroke order of the alphabet “F” in the method for manufacturing a package of the present embodiment. It is a figure explaining the example of the stroke order of the font of the Arabic numeral "9" in the manufacturing method of the package body of this embodiment. It is a figure which shows the example of the font and the stroke order of Arabic numeral (0-9) in the manufacturing method of the package body of this embodiment. It is a figure which shows the example of the font and the stroke order of the uppercase letters A to N of the alphabet in the manufacturing method of the package body of this embodiment. It is a figure which shows the example of the font and the stroke order of the uppercase letters OZ of the alphabet in the manufacturing method of the package body of this embodiment. It is a figure which shows the example of the font and the stroke order of the lowercase letters a to n of the alphabet in the manufacturing method of the package of this embodiment. It is a figure which shows the example of the font and the stroke order of the lowercase letters oz of the alphabet used in the manufacturing method of the package body of this embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all drawings, similar components are designated by the same reference numerals, and description thereof will be omitted as appropriate.
In order to avoid complication, (i) when there are a plurality of the same components in the same drawing, only one of them is coded and all of them are not coded, or (ii) especially in the figure. In 2 and later, the same components as in FIG. 1 may not be re-signed.
All drawings are for illustration purposes only. The shape and dimensional ratio of each member in the drawing do not necessarily correspond to the actual article.

In the present specification, the term "abbreviation" means to include a range in consideration of manufacturing tolerances, assembly variations, etc., unless otherwise specified explicitly.
In the present specification, the notation "a to b" in the description of the numerical range means a or more and b or less unless otherwise specified.

In the notation of a group (atomic group) in the present specification, the notation that does not indicate whether it is substituted or unsubstituted 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).
The notation "(meth) acrylic" herein represents a concept that includes both acrylic and methacrylic. The same applies to similar notations such as "(meth) acrylate".

<Manufacturing method of packaging>
FIG. 1 schematically shows a method for manufacturing a package of the present embodiment. More specifically, FIG. 1 schematically illustrates a process of printing a font of the capital letter "O" (O) of the alphabet in the manufacture of a package.
In FIG. 1A, the beam 2 irradiated from the laser apparatus 1 on the surface of the packaging material 10 including the base material layer and the laser coloring layer containing the component (X) that irreversibly develops color by laser irradiation. Spot 3 is hit. At the location where the spot 3 hits, the component (X) irreversibly develops a color.
Spot 3 is a solid arrow along the dotted line portion shown on the surface of the packaging material 10 (this dotted line is shown for illustration purposes only and does not exist on the actual surface of the packaging material 10). It is moved as shown by. That is, the spot 3 is moved along the line constituting the font of "O".
As described above, "O" is printed on the surface of the packaging material 10.

FIG. 1B is a diagram supplementing the “stroke order” of “O”. As described above, the spot 3 is continuously moved along the lines that make up the "O" font. Therefore, "O" is printed in the stroke order shown from left to right in FIG. 1 (B).

As a reminder, the method of drawing by moving the spot of the laser beam in only one predetermined direction (main scanning direction) is excluded from the present invention.
To reiterate, the spot 3 is moved two-dimensionally rather than one-dimensionally along the lines that make up the font.

In the present embodiment, as the font of the characters to be printed, a font that does not include an acute-angled portion, a three-way junction-shaped portion, and an intersection of lines is used.
This will be described in the font of the Arabic numeral "4" and the alphabet "E".

FIG. 2B is an example of the font of the number “4” in the conventional laser marking. There is an "acute angle" in the part α surrounded by the broken line. In addition, there is an "intersection between lines" in the portion β surrounded by the broken line.
On the other hand, FIG. 2A is an example of the font of the number “4” used in the method for manufacturing the package of the present embodiment. In the portion α surrounded by the broken line, a “gap” is intentionally provided so that an acute angle does not exist. Similarly, in the portion β surrounded by the broken line, a “gap” is intentionally provided so that the lines do not intersect with each other.

FIG. 3B is a font of the alphabet “E” in the conventional laser marking. There is a "three-way junction" in the portion γ surrounded by the broken line.
On the other hand, FIG. 3A is an example of the font of the alphabet “E” in the method for manufacturing the package of the present embodiment. In the portion γ surrounded by the broken line, a “gap” is intentionally provided so that the three-way junction-like portion does not exist.

According to the findings of the present inventors, by using a font such as FIG. 2 (A) and FIG. 3 (A), which does not include any acute-angled portion, three-way junction-shaped portion, or intersection of lines. The printed characters can be sharpened (for example, bleeding is reduced). The reason for this is not always clear, but it can be explained as follows.

The present inventors have investigated the causes of unclear characters printed in the past from various viewpoints, such as by changing the laser irradiation conditions in various ways. Through examination, it was presumed that one of the causes of this blur was local damage to the packaging material due to excessive laser irradiation.
Specifically, when a laser exceeding a certain amount of light is irradiated to a narrow range of the packaging material, the component (X) existing in the irradiated range is overheated. Due to the heat, a part of the packaging material is locally vaporized to create voids inside the packaging material. It is presumed that the outline of the character is blurred and unclear due to the spread of the colored component (X) or the like in the void.

The acute-angled portion, the three-way junction-shaped portion, and the intersecting portion between the lines included in the font used for the conventional laser marking are all portions where the irradiation amount (integrated light amount) of the laser beam is large. And, because of this large integrated light quantity, it is a part that tends to be overheated.
That is, the three-pronged portion and the intersection of the lines are more likely to be heated than the other portions because the laser beam is irradiated to the portion "twice" (usually, the average of the spots in the laser marking). Since the moving speed is extremely large (on the order of several m / s) compared to the size of the printed characters (on the order of about mm to cm), the heat generated by the first irradiation is naturally cooled in the relevant part. A second irradiation is done before the laser is used).
Further, in the vicinity of the acute angle portion, the two lines forming the acute angle are extremely close to each other. Therefore, “overlap” of laser beam spots occurs. In this "overlapping" portion, the integrated light amount becomes large and tends to be overheated. Further, since the acute-angled portion is a portion where the spot of the laser beam changes direction in the opposite direction, the moving speed of the spot becomes slow. At this point as well, the integrated amount of light increases and tends to overheat.

Furthermore, although the cause is not always clear, the present inventors have investigated, and as a result of the examination, apart from the above-mentioned damage to the packaging material, when the color development does not necessarily become dark even if the laser irradiation amount is increased, or when the laser color is increased. It was also found that when the irradiation amount is increased, the color density may decrease.
In other words, at the three-way junction, the intersection of lines, the acute-angled part, etc., as a result of irradiating more laser light than necessary, the color density is rather lowered, which also causes the blurring of characters. Was estimated.

Based on the above findings and estimations, the present inventors have newly created a font for characters used for printing by laser marking, which does not include an acute-angled portion, a three-way junction-shaped portion, and an intersecting portion between lines.
It is presumed that by using this font, local damage to the packaging material due to excessive laser irradiation or reduction of color density due to laser irradiation exceeding the required amount was suppressed, and clear printing became possible. To.

In the method of manufacturing the package of the present embodiment illustrated in FIG. 1, the method of moving the spot 3 (which can also be expressed as the “stroke order” of the characters) is described along the lines constituting the printed font. As long as the spot 3 is moved, it is not particularly limited, and is appropriately set from the viewpoint of printing efficiency (for example, shortening of printing time).

As an example, when a right-angled portion or an obtuse-angled portion is present in the printed font, the spot 3 may be continuously moved so that two lines forming the right-angled portion or the obtuse-angled portion are drawn in one stroke. preferable. By doing so, it is possible to reduce the distance and the number of times the laser device 1 is moved, which is considered to lead to a reduction in printing time.
For example, there is an obtuse angle at the upper left of the font of the Arabic numeral "5" shown in FIG. 4 (A). It is preferable that the two lines forming the obtuse angle are printed at once by moving the spot 3 continuously and without interruption as shown by the broken line arrow in FIG.
The same applies to the right-angled portion on the upper left of the alphabet “F” shown in FIG. 4 (B).

From another viewpoint, in the printed font, there is a line L that can be written with a single stroke in which a straight line and a curved line are connected, and the vicinity of one end P of the line L is a straight line, and the other end Q of the line L. When the vicinity of is a curved line, it is preferable that the spot 3 is continuously moved along the line L with one end P as a start point and the other end Q as an end point.
For example, the font of the Arabic numeral "9" shown in FIG. 5 is composed of a single-stroke line L in which a straight line and a curved line are connected. When the end point on the straight line side of the line L is P and the end point on the curved side is Q, the spot 3 is printed by being continuously moved to Q along the line L with P as the starting point. Is preferable.
By doing so, it can be expected that the printed characters will be made clearer (reduction of bleeding, etc.).

The reason why the printed characters become clearer by moving the spot 3 as described above is not always clear, but one of them is presumed as follows.
When the spot 3 is continuously moved from the start point to the end point of a certain line, due to the driving nature of a normal laser marking device (for example, due to the operation characteristics of the laser device 1), the moving speed of the spot 3 (initial speed) is inevitably near the start point. ) Tends to be late. If the initial velocity of the spot 3 is slow, the amount of light emitted by the laser tends to be excessive. As a result, although the degree is smaller than that of the acute-angled portion, the three-way junction-shaped portion, and the intersecting portion between the lines, the packaging material 10 is overheated and the printing is liable to be blurred.
However, if the vicinity of the start point is a simple "straight line", it becomes easier to suppress the slowdown of the initial velocity of the spot 3 as compared with the "curve" that requires complicated movement near the start point. It is presumed that this will further suppress the blurring of the print due to overheating.

In the method for manufacturing a package of the present embodiment, the thickness of the character line printed on the packaging material 10 is not particularly limited, and it is sufficient that a human can visually recognize it according to the purpose.
As an example, the thickness of the character line printed on the packaging material is preferably 0.4 mm or less, and more preferably 0.05 to 0.3 mm.
The "line thickness" here is the thickness of the line constituting the characters irreversibly printed on the packaging material 10, and is the line thickness of the printed portion after the packaging body is manufactured. It can be obtained by measuring the thickness. If the line thickness in the printed characters is not uniform, it is preferable that both the thickness of the thickest line portion and the thickness of the thinnest line portion fall within the above numerical range.

From another viewpoint, when the diameter of the spot 3 is d, the thickness of the character line printed on the packaging material is preferably d or less, more preferably 0.1 d to d, and even more preferably. Is 0.3d to 0.9d, particularly preferably 0.4d to 0.8d.
^{The diameter d of the spot 3 drops to 1 / e 2} (about 13.5%) when the light intensity at the center (the point where the light intensity is the strongest) is 1 (100%). It can be defined by the width of the strength of the part. Here, e is the base of the natural logarithm.
The diameter d of the spot 3 is typically 0.05 to 0.5 mm, preferably 0.1 to 0.3 mm.

The font of the characters to be printed will be additionally described.
As described above, the font of the characters to be printed is not particularly limited as long as it does not include sharp corners, three-pronged parts, and intersections of lines, and is not particularly limited, and is limited to Chinese characters, hiragana, katakana, Roman numerals, and Arabic numerals. It may be a font containing characters such as numbers and alphabets.
For food packaging applications, such as display of expiration dates and factory-specific numbers, it is preferable that at least Arabic numeral and alphabet (uppercase and lowercase) fonts can be printed.

Examples of fonts that can be used in the method for manufacturing the package of the present embodiment are shown in FIGS. 6 to 10 together with the stroke order (how to move the spot 3).
In FIGS. 6 to 10, the font itself is represented by a solid line. The stroke order is represented by a dashed arrow and a circled Arabic numeral.
Further, in FIGS. 6 to 10, a small ellipse surrounds a portion changed from the conventional font so as not to include an acute-angled portion, a three-way junction-shaped portion, and an intersecting portion between lines.

It is preferable to use appropriate software for printing. That is, the font and writing order information of the characters is read in advance into the laser device 1 (or the control computer connected to the laser device 1) by appropriate software, and the laser is used based on the information during the printing process. It is preferable to control the device 1 (controlling how the spot 3 is moved, turning the beam 2 on / off, etc.). Examples of software that can be used for such a purpose include "Marking Builder2 (ver. 7) Font Architect" manufactured by KEYENCE CORPORATION.

Each component in FIG. 1A will be additionally described.
-Laser device 1, beam 2 and spot 3
Any light source can be used as the light source of the laser device 1. For example, a pulse laser, a semiconductor laser, a fiber laser, a YAG laser, a YVO ₄ laser or the like using a Q switch or a shutter can be used.
_{The light source of the laser apparatus 1 is preferably a CO 2} pulse laser or a fiber laser, and more preferably a CO ₂ pulse laser, from the viewpoint of availability of the apparatus and the color development property of the coloring material described later.

The average output P [W] of the light source of the laser apparatus 1 is not particularly limited, but is, for example, 0.5 [W] or more and 30 [W] or less, preferably 1.0 [W] or more and 20 [W] or less. The average output P [W] can be set by the output% of the laser output condition. For example, in a laser with a maximum output of 30 [W], if the output is set to 30%, the average output P [W] becomes 9 [W]. By setting the value within this numerical range, it becomes easy to achieve both the print density and the production cost.
When the light source of the laser apparatus 1 is a pulse laser, the repetition frequency is not particularly limited, but is 5 kHz or more and 50 kHz or less, more preferably 10 kHz or more and 30 kHz or less. By setting the value within this numerical range, it becomes easy to achieve both the print density and the production cost.

The wavelength of the beam 2 is not particularly limited, but is, for example, 10.6 μm when _{the light source of the laser device 1 is a CO 2 pulse laser.}

The method for appropriately moving the spot 3 is not particularly limited, and a known method may be appropriately applied.
Typically, the spot 3 can be appropriately moved (controlled) by a mechanism such as a known galvanometer mirror or fθ lens.
Further, the spot 3 may be appropriately moved (controlled) by a mechanism for moving the laser light source itself in the X direction and the Y direction, which is a so-called "flat bed type".
As a reminder, FIG. 1A is just a schematic explanatory view, and the means for appropriately moving the spot 3 is not specified.

The moving speed of the spot 3 may be appropriately adjusted depending on the productivity, the content of the component (X) contained in the packaging material 10, the desired color development concentration, and the like. As an example, it is 0.5 to 10 m / s, preferably 1 to 6 m / s. Within this numerical range, it becomes easier to achieve both industrial productivity (drawing speed) and improvement of color density.
The "moving speed of the spot 3" here means that the total length of the lines included in the characters to be printed is L _t , and the printing starts (the beginning of the spot 3 hitting) and the printing ends (the spot 3 hitting). When the time until the end) is T, it is defined by _{L t / T.}

・ Packaging material 10
The packaging material 10 includes a base material layer and a laser coloring layer containing a component (X) that irreversibly develops color by laser irradiation.

As used herein, the term "packaging material" is a concept that broadly includes materials generally used for accommodating or packing articles, and is used when transporting, transporting, or selling solid, liquid, or gaseous articles. It broadly includes "boxes", "containers", "bags", and materials thereof (in other words, it is not limited to the two-dimensional packaging material 10 as shown in FIG. 1 (A)). In addition, a medium such as a sticker or a label on which product information is displayed is also included in the packaging material in the present specification.

Supplementally as a supplement from another viewpoint, in the present specification, the “method for manufacturing a package” refers to (i) a method in which a spot 3 is applied to a packaging material 10 in which a product is packed or contained to develop a color of a laser color-developing layer. ii) A method in which a spot 3 is applied to a packaging material 10 in which a product is not packed or housed to develop a color of a laser color-developing layer, and then the product is packed or stored using the packaging material 10, (iii) laser. The method includes a method in which the spot 3 is applied to a seal or label provided with a color-developing layer to develop a color of the laser color-developing layer, and then the seal or label is attached to another packaging material 10.

Incidentally, regarding the positional relationship (arrangement) between the base material layer and the laser coloring layer, the beam 2 is usually irradiated so that the laser coloring layer is closer to the beam 2 than the base material layer. In other words, the irradiation of the beam 2 to the packaging material 10 is usually performed from the surface opposite to the base material layer included in the packaging material 10.
To describe with reference to the figure, in FIG. 1A, a laser coloring layer is usually present on the front side (visible side) of the packaging material 10, and a normal base material is present on the back side (invisible side) of the packaging material 10. There are layers.

When the material of the base material layer, which will be described later, is paper or metal, the arrangement of the base material layer and the laser coloring layer as described above is preferable from the viewpoint of the transparency of the beam 2.
When the material of the base material layer is a resin film, the above arrangement is not always necessary from the viewpoint of transparency. However, when the packaging material 10 is overheated by laser irradiation, there is a slight possibility that a part of the material constituting the packaging material 10 is "scattered". Considering this possibility, even when the material of the base material layer is a resin film, it is preferable that the base material layer and the laser coloring layer are arranged as described above. This is because even if the problem of "scattering" occurs, it is possible to prevent the scattered matter from contaminating the packaged article.

The base material layer of the packaging material 10 will be described.
The material of the base material layer is not particularly limited as long as it can be generally used as a packaging material (container). Typically, the resin film, paper, metal and the like described below are mentioned, but the present invention is not limited to these. Further, it may be a base material in which these are composited.

In particular, when the base material layer is a base material layer containing a resin film, the resin film is easily damaged by overheating, so that the effect of the method for manufacturing the package of the present embodiment can be remarkably obtained.
When the base material layer contains a resin film, examples of the material thereof include known thermoplastic resins. For example, polyolefins such as polyethylene, polypropylene, poly (4-methyl-1-pentene), poly (1-butene); polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate; nylon-6, nylon- 66, Polyesters such as polymethaxylene adipamide; Polyvinyl chloride; Polyvinylidene chloride; Ethylene / vinyl acetate copolymers; Polyesters; Polyesters; Ionomers; etc. These are appropriately selected depending on the storage stability of the article to be packaged and the packaging form (presence or absence of heat sealing treatment, etc.).
The resin film may be stretched or unstretched. This is also appropriately selected depending on the article to be packaged and the like.

The resin film may have a laminated structure of two or more layers. As an example, a resin film having a laminated structure can be obtained by laminating two or more different types of films. Further, as another example, there is also a coextrusion method, a method of applying a solution resin material to the surface of a certain resin film and drying it to obtain a laminated structure.
The resin film may contain an additive component other than the resin. For example, additives such as antifogging agents and antiblocking agents, and adhesive resins such as urethane-based resins, urea-based resins, melamine-based resins, epoxy-based resins, and alkyd-based resins may be contained. Further, the resin film is a dye (for example, a pigment) from the viewpoints of designability, contrast when printing printing ink, hiding property of the contents of the package, and avoiding deterioration of the contents due to light incident. , More specifically, a white pigment, etc.) may be included.

When the material of the base material layer is paper, the paper may be any paper, and may be Japanese paper, Western paper, cardboard, kraft paper, or the like. One preferred embodiment is corrugated cardboard. The "corrugated cardboard" here may have a box-shaped shape, a box-shaped sheet before molding, or any other shape.
The surface of the paper may be provided with a layer for facilitating the uniform formation of the laser color-developing layer and a layer (anchor coat layer) for improving the adhesion of the laser color-developing layer. Further, the surface of the paper may be pretreated to prevent the laser color-developing layer from peeling off.

When the material of the base material layer is a metal, the metal is typically aluminum or iron, but of course other metals are not excluded. The metal may be an alloy. Of course, a metal base material having a plated surface such as tinplate, or a metal base material having a resin layer or a coating layer formed on the surface for corrosion prevention and the like can also be applied.

The laser color-developing layer of the packaging material 10 will be described.
The packaging material 10 includes a laser coloring layer containing a component (X) that irreversibly develops color by laser irradiation. As a result, printing can be performed when the spot 3 is applied.
The phrase "irreversibly develops color" means that the color once generated cannot be erased and recolored. It may be possible to change a color to another color, but it is not possible to revert to the originally generated color after returning to the empty or original color. However, the phrase "irreversibly develops color" does not exclude the possibility of gradual fading in everyday environments such as exposure to sunlight.
Further, in the present specification, the component (X) that irreversibly develops color by laser irradiation is also simply referred to as "component (X)".

・ Ingredient (X)
The component (X) is not particularly limited. For example, a leuco dye, a copper-molybdenum composite oxide, a copper phenylphosphonate, etc., which are known as known laser color-developing materials, can be used.

Particularly preferred as the component (X) are (i) particles of the inorganic metal oxyanion compound described below and / or (ii) a combination of a color former and a color developer. These are particularly preferable from the viewpoints that the color density can be increased and the change with time is small.
These color-developing components develop vivid colors by a chemical reaction, and have characteristics such as easy to increase the color-developing density. On the other hand, the packaging material 10 tends to generate heat due to the heat of the chemical reaction in addition to laser irradiation. There is also. Further, when the laser irradiation is excessive, the color density tends to decrease on the contrary.
However, according to the method for producing a package of the present embodiment, it is possible to suppress excessive laser irradiation, so that it is possible to suppress damage to the packaging material 10 and suppress a decrease in the color development density while obtaining a high color development density. Be done.

(I) Particles of Inorganic Metal Oxyane Compound Examples of the inorganic metal oxyanion compound include compounds containing a transition metal oxyanite such as molybdate, tungstate, vanadinate, and chromate (a salt of transition metal oxyic acid). Etc.) can be used. Among these, a compound containing molybdenum oxyanion (molybdate or the like) is preferable. The molybdenum oxyanion heptamolybdate anion _{(Mo 7 O} ^{24 2-)} and octamolybdate anion _{(Mo 8 O} ^{26 4-)} and the like.

Examples of the counter cation of the inorganic metal oxyanion include an alkali metal cation, an alkaline earth metal cation, and an onium cation. The counter cation, primary amine which is protonated, protonated secondary amine, protonated tertiary amine, unsubstituted ammonium cation (NH 4 ^₊₎ and the like are preferable. Among these, unsubstituted ammonium cation _(NH ^{4 +)} is more preferable.

A particularly preferable inorganic metal oxyanion compound is ammonium molybdate, and a particularly preferable one is ammonium octamolybdate ((NH ₄ ) ₄ , Mo ₈ O ₂₆ ).

_{The median diameter (D 50A} ) of the particles of the inorganic metal oxyanion compound 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 commercially available and the median diameter is described in a catalog or specification, the described value is used as the median diameter. If this is not the case, the median diameter can be determined based on the measurement data of a laser diffraction type particle size measuring device (for example, a laser diffraction type particle size measuring device SALD3000J manufactured by Shimadzu Corporation).

When the particles of the inorganic metal oxyanion compound are irradiated with laser light, they irreversibly develop color due to changes in the oxidation state and the like.

(Ii) Combination of color former and color developer As the color former here, for example, a compound known as a leuco dye can be used. The leuco dyes that can be used are not particularly limited, and known phthalide-based, fluorane-based, triarylmethane-based, benzoxazine-based, quinazoline-based, spiropyran-based, quinone-based, thiazine-based or oxazine-based leuco dyes can be used. ..

More specific color formers (leuco dyes) include the compounds described in paragraphs 0021 of JP2015-193323A and the compounds described in paragraphs 0047 to 0056 of Japanese Patent No. 5914235.

As the color developer, known ones can be appropriately used. That is, those in which the component that causes the above-mentioned color former is generated by the laser light or the heat generated by the irradiation of the laser light can be appropriately used.

Examples of the color developer include a compound having a phenolic hydroxyl group, a metal salt of a compound having a phenolic hydroxyl group, and the like. For example, tertiary butyl catechol, n-stearylphenol, o-phenylphenol, hexafluorobisphenol, n-butyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, dodecyl gallate, 2,2-bis (4). -Hydroxyphenyl) propane, 4,4'-dihydroxydiphenylsulfone, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, bis (4-hydroxy) Phenyl) sulfide, 1-phenyl-1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -3-methylbutane, 1,1-bis (4-hydroxyphenyl) -2 -Methylpropane, 1,1-bis (4-hydroxyphenyl) n-hexane, 1,1-bis (4-hydroxyphenyl) n-heptane, 1,1-bis (4-hydroxyphenyl) n-octane, 1 , 1-bis (4-hydroxyphenyl) n-nonane, 1,1-bis (4-hydroxyphenyl) n-decane, 1,1-bis (4-hydroxyphenyl) n-dodecane, 2,2-bis ( 4-Hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) ethyl propionate, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxyphenyl) ) Hexafluoropropane, 2,2-bis (4-hydroxyphenyl) n-heptane, 2,2-bis (4'-hydroxyphenyl) n-nonane and the like, and at least one of these can be used. ..

In the present embodiment, the color developer preferably contains a compound represented by the following general formula (I).
The compound represented by the general formula (I) generates heat and melts when irradiated with laser light. It is considered that a part of the melt reacts and interacts with the above-mentioned color former (leuco dye) to develop a color.

In general formula (I),
X is a silicon atom or a boron atom,
E and F are independently divalent organic groups, respectively.
R ¹ and R ² are independently monovalent organic groups, respectively.
If X is a silicon atom, then (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 connected to each other 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 independent hydrogen atoms or monovalent organic groups, and two of them may be linked to each other to form a ring structure.
n is 1 or 2.

A preferred embodiment of the compound represented by the general formula (I) will be described.
X is preferably a boron atom.
The divalent organic group of E preferably forms a 5- or 6-membered ring with the two O atoms and X to which E is attached.
Specific examples of the divalent organic group of 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 to which these groups are linked. ..

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

The divalent organic groups E and F are preferably any 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 1 to 4 carbon atoms), an alkoxy group (preferably 1 to 4 carbon atoms), a halogen atom, an amino group or a carboxy group. ..

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

Examples of the monovalent organic group of R ³ , R ⁴ and R ⁵ include an alkyl group (preferably 1 to 12 carbon atoms), a hydroxyalkyl group (preferably 1 to 6 carbon atoms), an aryl group (phenyl group and the like), and the like. Examples thereof include an aralkyl group (preferably 7 to 11 carbon atoms) and an arylsulfonyl group (preferably 6 to 10 carbon atoms). 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.
Further, two of R ³ , R ⁴ and R ⁵ may be connected 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 the compounds listed in paragraphs 0027 and 0039 of Japanese Patent No. 5914235.

Regarding the ratio of the color-developing agent to the color-developing agent, the color-developing agent is usually 0.1 to 10 parts by mass, preferably 0.2 to 7 parts by mass, and more preferably 0.5 to 10 parts by mass with respect to 1 part by mass of the color developing agent. 5 parts by mass.

The abundance of the component (X) (preferably the above (i) and (ii)) in the laser color-developing layer is not particularly limited as long as the visible color is produced by irradiation with the laser light, but is preferably 1 to 5 g / g. It is m ^2.
This amount can be adjusted by increasing or decreasing the amount of the component (X) in the ink composition for forming the laser color-developing layer, which will be described later, or increasing or decreasing the coating amount of the ink composition.

The layer structure of the packaging material 10, the thickness of each layer, and the like will be described.
The packaging material 10 is not particularly limited as long as it includes a base material layer and a laser coloring layer, and may include a third layer different from these layers. As the third layer, for example, a resin layer covering the laser coloring layer, a layer for facilitating uniform formation of the laser coloring layer on the base material layer, and an adhesion of the laser coloring layer to the base material layer are improved. A layer for the purpose (anchor coat layer), an inorganic material layer (plating layer, vapor deposition layer, etc.), a resin layer or a coating layer for corrosion prevention, etc. may be provided. It is one preferred embodiment that the packaging material 10 includes an inorganic layer (for example, an aluminum-deposited layer) when the method for producing a package of the present embodiment is applied to the food field.

Among the above-mentioned third layers, a resin layer covering the laser coloring layer will be described in particular.
The resin layer is preferably provided from the viewpoints of improving the smoothness of the surface of the packaging material 10, preventing the laser coloring layer from falling off, improving the drawing quality, and preventing ablation when the laser coloring layer is overheated. ..

It goes without saying that the packaging material 10 may be provided with the above-mentioned third layer in any arrangement, but the resin layer covering the laser coloring layer is preferably provided on the upper surface of the laser coloring layer. In other words, when the packaging material 10 includes a resin layer covering the laser coloring layer, the preferable layer structure of the packaging material 10 is, in order, a base material layer, a laser coloring layer, and a resin layer covering the laser coloring layer ( In other words, it is preferable that the base material layer is on one side of the laser coloring layer and the resin layer covering the laser coloring layer is on the other side). It should be noted that a mode in which a separate layer is provided between these layers is not excluded. And preferably, the beam 2 is irradiated from the side of the resin layer covering the laser coloring layer.

When the packaging material 10 includes a resin layer that covers the laser coloring layer, the material and materials of the resin layer are not particularly limited. Specifically, low-density polyethylene, unstretched and stretched polypropylene, polyester (polyethylene terephthalate (PET), etc.), polyamide (nylon, etc.), polystyrene, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyvinyl alcohol film, etc., and poly Films such as polypropylene, polyester, nylon, and cellophane coated with vinylidene chloride and the like can also be mentioned. Further, a vapor-deposited film, for example, a PET film on which aluminum, silica, or the like is vapor-deposited can also be used.

Further, the resin layer covering the laser color-developing layer may be provided by applying an appropriate coating liquid on the laser color-developing layer and drying / curing the laser layer. Examples of the coating liquid include those containing (1) a resin, (2) a resin precursor (polymerizable monomer, oligomer, prepolymer, etc.), and a heat or photopolymerization initiator. .. As the coating liquid, it is also possible to apply an overprint varnish or the like known in the printing field.
For specific components of the applicable coating liquid, for example, the description in paragraphs 0037 to 0044 of JP-A-2007-313875 can be referred to.

Further, the resin layer covering the laser coloring layer may contain an additive component other than the resin, as in the case of the resin film as the base material layer. For example, additives such as antifogging agents and antiblocking agents, adhesive resins such as urethane-based resins, urea-based resins, melamine-based resins, epoxy-based resins, and alkyd-based resins, pigments (pigments, for example, white pigments), etc. It may be included.

The thickness of the laser color-developing layer depends on the amount of the component (X) and the like, but is usually 1 to 30 μm, preferably 2 to 20 μm.
When the packaging material 10 is provided with a resin layer covering the laser coloring layer, the thickness thereof is usually 0.1 to 300 μm, preferably 1 to 250 μm, and more preferably 10 to 210 μm.
The thickness of the base material layer is not particularly limited depending on the available resin film, paper, metal (metal plate, metal container), etc., but in the case of a resin film, for example, it is usually 5 to 100 μm, preferably 10 to 50 μm. In the present embodiment, since the effect of suppressing overheating due to laser irradiation is also expected, even if a thin resin film is used, it is expected that wrinkles are suppressed due to heat shrinkage of the resin film and pinholes are suppressed.

The manufacturing method of the packaging material 10 will be described.
The method for obtaining the packaging material 10 is not particularly limited, but for example, at least the ink composition containing the component (X) is selected from flexographic printing, gravure printing, offset printing, screen printing, resin letterpress printing and pad printing. It can be obtained by printing on a base material constituting a base material layer or a base material constituting the above-mentioned third layer by any printing method.
At this time, the ink composition may be printed on the entire one side of the base material constituting the base material layer or the base material forming the third layer described above, or may be printed on only a part of the one side. Good.

When the packaging material 10 includes a resin layer that covers the laser color-developing layer, for example, the resin that covers the base material layer, the laser color-developing layer, and the laser color-developing layer by the method of the following procedure 1, step 2, or step 3. A packaging material 10 with a layer can be obtained. Of course, the packaging material 10 may be obtained by a procedure other than these.

・ Step 1:
(1) Prepare a resin film constituting a resin layer covering the laser coloring layer.
(2) A laser color-developing layer is provided on a part or all of one side of the resin film by a printing method or the like.
(3) By a known laminating method (for example, a dry laminating method), the surface of the resin film provided with the laser coloring layer provided with the laser coloring layer is bonded to the film constituting the base material layer.

・ Procedure 2:
(1) Prepare a resin film constituting the base material layer.
(2) A laser color-developing layer is provided on a part or all of one side of the resin film by a printing method or the like.
(3) By a known laminating method (for example, a dry laminating method), the surface of the resin film provided with the laser coloring layer provided with the laser coloring layer and the resin film constituting the resin layer covering the laser coloring layer are attached. match.

・ Procedure 3:
(1) Prepare a resin film constituting the base material layer.
(2) A laser color-developing layer is provided on a part or all of one side of the resin film by a printing method or the like.
(3) An appropriate coating liquid is applied onto the provided laser coloring layer, and the resin layer is provided to cover the laser coloring layer by drying and curing.

In the above procedure 1 or 2, the dry laminating method is mentioned as a known laminating method, but of course, laminating methods other than the dry laminating method are not excluded. However, the dry laminating method is preferable from the viewpoint of suppressing the possibility that the laser color-developing layer develops color or deteriorates due to heat during the production of the packaging material 10.

When the base material layer and / or the resin layer covering the laser coloring layer is composed of a resin film, the resin film may be subjected to surface treatment such as corona treatment. This can be expected to improve the affinity with other layers.

The components that can be contained in the ink composition, the physical characteristics of the ink composition, and the like will be additionally described.
・ Ingredient (X)
The ink composition contains the above-mentioned component (X). The component (X) is preferably a combination of the above-mentioned particles of (i) an inorganic metal oxyanion compound and / or (ii) a color former and particles of a compound represented by the general formula (I).

The amount of the component (X) in the ink composition is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, still more preferably 30 to 75% by mass, particularly based on the total amount of the ink composition. It is preferably 35 to 70% by mass.
Further, based on the total amount of the non-volatile components of the ink composition, the amount of the component (X) is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and further preferably 40 to 65% by mass. is there.

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.
When the component that 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), it is represented by the color former and the general formula (I). It is preferable that the total amount (sum) of the compounds is in the above numerical range.

-Pigment particles The ink composition preferably contains pigment particles. The pigment particles here are a combination of the above-mentioned component (X) (for example, particles of (i) an inorganic metal oxyanion compound, (ii) a color former, and particles of a compound represented by the following general formula (I). ) Is a different component.

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 and matching the color of the laser color development layer with the color of the corrugated cardboard surface.
In one aspect, the pigment particles are preferably white pigment particles. Examples of the 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 and the like. In particular, the purity (content) of rutile-type titanium dioxide in the total amount of the white pigment particles is preferably 85% by mass or more, more preferably 90% by mass or more.

Titanium dioxide has several crystalline forms. Crystalline titanium dioxide other than rutile type may be slightly unstable chemically or may have catalytic ability to decompose other components in the ink composition. Therefore, it is preferable that the pigment particles are composed of rutile-type titanium dioxide having the above-mentioned purity. With this configuration, even if there is a long time between the assembling process and the laser image forming process, it is further suppressed that the laser color-developing layer deteriorates and the color-developing density drops (in conventional heat-sensitive materials and the like, aging There were many cases where the color density decreased due to this).
As a method for obtaining high-purity rutile-type 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 value described in a catalog, specifications, or the like, or a value measured by a laser diffraction type particle size measuring device, like _{the D 50A.}
The shape of the pigment particles is preferably substantially spherical or substantially elliptical.

The aspect ratio of the pigment particles represented by the ratio (L / S) of the major axis L to the minor axis S is preferably 1 to 5, and more preferably 1 to 3. Within this range, the surface of the laser color development layer can be made smoother, and the contrast of laser color development can be further enhanced.
Here, when the pigment particles are commercially available and the aspect ratio is described in a catalog, specifications, or the like, the described value is used as the aspect ratio. If this is not the case, the aspect ratio is the average of the aspect ratios of 50 arbitrary particles when the 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 the non-volatile components of the ink composition.

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

With the above configuration, the pigment particles can enter the "gap" 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 particles of the inorganic metal oxyanion compound. That is, since the amount of pigment particles can be increased while maintaining the color development concentration (correlation with the amount of the inorganic metal oxyanion compound), the effect of the pigment particles can be sufficiently obtained. Therefore, a higher contrast image can be obtained by laser irradiation.

-Particle dispersion treatment and dispersant In the ink composition, the component (X) and the above pigment particles may be dispersed with a dispersant or the like.
Dispersants are appropriately applied from known ones, but are random copolymers or block copolymers containing pigment-compatible structures (eg, amines, esters, alcohols and carboxylic acids, and / or salt structures thereof). Can be mentioned. Examples of 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. ..
Also, known surfactants can be applied. Examples of the surfactant include a low molecular weight surfactant, a high molecular weight surfactant, a nonionic surfactant, a cationic surfactant, an anionic surfactant and the like.

-The resin ink composition preferably contains a resin. By including the resin, the ink composition has an appropriate viscosity, and it becomes easy to uniformly print the ink composition on the base material layer. In addition, the above-mentioned effects such as promotion of dispersion of each particle and suppression of sedimentation can be expected.

The resin can be used without particular limitation as long as it is used in the fields 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 acetate. Examples thereof include copolymers. 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 copolymer, and the like.

The weight average molecular weight of the resin is not particularly limited, but is, for example, 3000 to 100,000, preferably 5000 to 50000, and more preferably 5000 to 20000. Within this range, the ink composition can have an appropriate viscosity. The dispersity 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 can be obtained by, for example, GPC (Gel Permeation Chromatography) measurement when polystyrene is used as a standard substance.

The glass transition temperature of the resin is not particularly limited, but is, for example, −50 to 150 ° C., preferably -40 to 100 ° C., and more preferably -15 to 50 ° C. Within this range, the fluidity of the ink composition can be made appropriate.
The glass transition temperature of the resin can be measured by a differential scanning calorimeter (DSC) in accordance with JIS-K7121.

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 the non-volatile components of the ink composition.

-Solvent The ink composition preferably contains a solvent.
The solvents that can be used are roughly classified into water, petroleum-based solvents, vegetable oils and fats, 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-based 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 No. 4 manufactured by JX Nikko Nisseki Energy Co., Ltd. , AF solvent No. 5, AF solvent No. 6, AF solvent No. 7, and the like.
Examples of vegetable oils and fats include soybean oil, linseed oil, tung oil, palm oil, palm oil, rice bran oil and the like. In particular, when vegetable fats and oils are used, rice bran oil containing 20% by mass or more of the fats and oils is preferable.

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

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

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 one type of the polymerizable compound may be used, or two or more types may be used in combination.

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) acryloyl morpholine.

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) Glycoldi (meth) acrylate, alkane (4-12 carbon atoms) glycol ethylene oxide adduct (2-20 mol) di (meth) acrylate, alkane (4-12 carbon atoms) glycolpropylene oxide adduct (4-12) 2 to 20 mol) di (meth) acrylate, hydroxypivalyl hydroxypivalate di (meth) acrylate, tricyclodecanedimethylol di (meth) acrylate, bisphenol A ethylene oxide adduct (2 to 20 mol) di (meth) Bifunctional (meth) acrylate monomers such as acrylate, hydrogenated bisphenol A di (meth) acrylate, hydrogenated bisphenol A ethylene oxide adduct (2-20 mol) di (meth) acrylate.

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, ditrimethylol propane tetra (meth) acrylate, ditrimethylol propane Tetra-functional vinyl compounds such as ethylene oxide adduct (4-40 mol) tetra (meth) acrylate, ditrimethylolpropanpropylene oxide adduct (4-40 mol) tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, A tetrafunctional or higher functional acrylate monomer such as dipentaerythritol ethylene oxide adduct (6 to 60 mol) hexa (meth) acrylate and dipentaerythritol propylene oxide adduct (6 to 60 mol) hexa (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 further preferably 15 to 50% by mass in all the components of the ink composition.

As the photopolymerization initiator, known ones can be appropriately used. Further, two or more kinds of photopolymerization initiators may be used in combination.
Specific examples of the photopolymerization initiator include α-hydroxyketone photoinitiator, α-aminoketone photoinitiator, bisacylphosphine photoinitiator, monoacylphosphine oxide, and bisacylphosphine oxide, for example, 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] protease] and the like. These are manufactured by BASF and sold under names such as the IRGACURE® series. Of course, other photopolymerization initiators 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, still more preferably 3 to 10% by mass, based on all the components of the ink composition.

-Other components: Various additives In addition to the above components, the ink composition may contain various additives such as leveling agents, dispersion aids, rheology adjusters, antifoaming agents, metal soaps, and antioxidants.

As the rheology adjuster, for example, the following can be used.
Compounds having two or more amide bonds in one molecule: Disparon series manufactured by Kusumoto Kasei Co., Ltd., etc.
Compounds having two or more urea bonds in one molecule: products of Big Chemie Japan Co., Ltd., BYK-410, BYK-E410, BYK-415, BYK-420, BYK-E420, BYK-D410, BYK-430, etc.
Fatty acid amide: Nihon Kasei Co., Ltd. products, Diamid series, etc.
Constituent pigments: bentonite, silica, clay, white carbon, precipitated barium sulfate, aluminum silicate, kaolin, etc.

Associated Leology Adjuster: Acrylic Swelling Associated Leology Adjuster and / or Urethane Associated Leology Adjuster, 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 (manufactured by Roam & 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, RheovisPE1332, PU1190, PU1191, PU1214, PU1215, PU1250, PU1251, PU1256, PU1270, PU1280, PU1291 (BASF), RHEOLATE266, 288, 244, 255, 278 (made by RHEOX), SN thickener A-803, A-804, A-807, A-812, A-814 (manufactured by Sannopco), etc.

Polymer-type rheology regulators: alkali-soluble polymer and / or polyethylene glycol rheology regulators with a weight average molecular weight in the range of 100,000 to 3 million, specifically Primal ASE-60, TT-615, ASE-75, ASE-108, RM-5, ASE-95NP (manufactured by Roam & 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 (manufactured by Toa Synthetic Co., Ltd.) and the like.
By using the rheology adjuster, the viscosity of the ink composition, which will be 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, based on all the components of the ink composition.

-Physical characteristics of ink composition (viscosity behavior, etc.)
Regarding the viscosity of the ink composition, it is preferable that the viscosity η ₁ measured at 25 ° C. and a shear rate of 1s ^-1 is 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 It is more preferable, and it is particularly preferable that it is 10 or more.
There is no particular upper limit to the value of η ₁ / η _{2 , but from a realistic point of view, 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 above-mentioned resin or by using an appropriate amount of the above-mentioned rheology adjusting agent.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted. Further, the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.

Embodiments of the present invention will be described in detail based on Examples and Comparative Examples. The present invention is not limited to the examples.

<Manufacturing example 1: Preparation of packaging material>
(1) Preparation of First Film Using a gravure printing apparatus and an ink composition (shown below), a laser coloring layer was formed on a corona-treated surface (one side) of a biaxially stretched polypropylene film having a thickness of 20 μm. This was used as the first film.
The amount of the ink composition was such that the amount of solid content (nonvolatile component) on the printing surface was 4.0 g / m ² .
The linear speed of rotation of the plate cylinder of the gravure printing apparatus was set to 250 m / min. As the plate cylinder, a gravure roll produced by a process of laser exposure, development and corrosion was used. The number of lines of this gravure roll was 150 lines / inch, and the plate depth (depth of the recess provided in the plate cylinder) was 40 μm.

As the ink composition, the following materials were sufficiently mixed and dispersed. _{The value of η 1} / η ₂ of this ink composition was 2 or more.
-Laser color development component: ammonium octamolybate particles, particle size (D _50A ) 1.5 μm 20 parts by mass ・ Pigment particles: titanium dioxide, particle size (D _50B ) 0.5 μm, substantially spherical (aspect ratio 1), rutile type Purity 90% by mass 8 parts by mass ・ Resin: Weight average molecular weight 1000 to 30000, glass transition temperature around 10 ℃, urethane resin 15 parts by mass, vinyl chloride vinyl acetate copolymer 5 parts by mass ・ Solvent: methyl ethyl ketone 40 parts by mass, acetic acid 5 parts by mass of ethyl, 5 parts by mass of 2-propanol (isopropyl alcohol)
・ Additives: fatty acid amides, dispersants (surfactants), antioxidants, etc. 2 parts by mass in total

(2) Preparation of Second Film An unstretched polypropylene (CPP) film having a thickness of 25 μm was prepared as a film different from the above-mentioned first film. The corona-treated surface on one side was coated with an ester-based laminating adhesive and dried by heating. As a result, a second film having an adhesive layer provided on one side was obtained.
The coating method was a gravure roller coating method. The amount of the adhesive applied was 4.0 g / m ² .

(3) Laminating the first film and the second film (dry laminating)
The laser color-developing layer of the first film and the adhesive layer of the second film are opposed to each other, and the packaging material in the laminated form (that is, the laser color-developing layer is formed of the base material of the first film and the second film by the dry laminating method. (Packaging material sandwiched between the base material) was produced.

<Manufacturing Examples 2-18: Preparation of packaging material>
A packaging material was prepared in the same manner as in Production Example 1 except that the types and thicknesses of the first film and the second film were changed as shown in Table 1.

<Manufacturing Examples 19 to 24: Preparation of Packaging Material>
First, a laminated film was obtained in the same manner as in Production Example 1 except that the types and thicknesses of the first film and the second film were changed as shown in Table 2. Then, the surface of the second film of the obtained film and the third film shown in Table 2 were opposed to each other and bonded by a dry laminating method. By this procedure, packaging materials in the laminated form of Production Examples 19 to 24 were produced (Table 2).

The film abbreviations in Tables 1 and 2 are as follows.
OPP: Biaxially stretched polypropylene film CPP: Non-stretched polypropylene film VMPET: Polyethylene terephthalate film with aluminum vapor deposition VMCPP: Non-stretchable polypropylene film with aluminum vapor deposition WOPP: Biaxially stretched polypropylene film containing white pigment LLDPE: Linear short chain branched polyethylene film PET: Polyethylene terephthalate film WPETG: Polyethylene terephthalate film containing white pigment Ny: Nylon film EVA + EAA: Film PE made of a mixed resin of ethylene / vinyl acetate copolymer and ethylene / acrylic acid copolymer : Polyethylene film PVC: Polyvinyl chloride film Al: Metal aluminum foil EVOH: Ethylene-vinyl alcohol copolymer film PVDC: Polyvinylidene chloride film

Among these films, as for the films other than Al, VMCPP and VMPET, those having corona treatment on one side were used as described in Production Example 1 and the like.
Further, for VMCPP and VMPET, the first film and the second film were bonded so that the vapor deposition surface was on the inside.

<Examples 1 to 24: Manufacture of package>
As a laser marking device, a device "ML-Z9520" (light source: CO ₂ laser) manufactured by KEYENCE Corporation is used, and a spot of a laser beam is applied to each of the packaging materials of Production Examples 1 to 24 described above, and the character string "LOT-" is applied. 4EA89 ”was printed to manufacture a package. The laser beam was irradiated from the side of the surface corresponding to the first film in each packaging material. The average output of the laser was 9 W, the spot diameter was 0.2 μm, and the moving speed (average) of the spot 3 was about 3 m / s.
The font information (including the stroke order) of the printed characters here is as shown in FIGS. 6 to 10. The font information was input to the above device in advance using the software "Marking Builder2 (ver.7) Font Architect" manufactured by KEYENCE CORPORATION.
The size of the characters printed here was approximately 4 mm in length × 3 mm in width, and the line thickness was 0.12 mm, which was almost uniform.

When the printed characters were observed, no particularly unclear parts such as bleeding were observed in all of Examples 1 to 24. That is, by the method for manufacturing a package of the present embodiment, clear characters can be printed in the production of the package including the printing process by laser marking.

<Comparative Examples 1 to 24: Manufacture of Package>
In Examples 1 to 24, Examples 1 to 24 except that the conventional font including an acute angle portion, a three-way junction portion, or an intersection between lines is used as the font information (including the stroke order) of the printed characters. The packaging was manufactured by printing in the same manner as in the above.
As a result, bleeding and the like were confirmed especially in the acute-angled portion, the three-way junction-shaped portion, or the intersection of the lines, resulting in unclear printing.

1 Laser device 2 Beam (laser beam)
3 Spot 10 Packaging material

Claims (7)

A printing process in which a spot of a laser beam is applied to a packaging material including a base material layer and a laser coloring layer containing a component (X) that irreversibly develops color by irradiation with the laser beam, and characters are printed on the packaging material. It is a manufacturing method of a package including
As the font of the characters to be printed, a font that does not include acute-angled parts, three-way junctions, and intersections of lines is used, and
A method of manufacturing a package in which the spots are moved along the lines that make up the font. The method for manufacturing a package according to claim 1.
There is a right-angled part or an obtuse-angled part in the font,
A method for manufacturing a package in which the spots are continuously moved so that two lines forming the right-angled portion or the obtuse-angled portion are drawn in one stroke. The method for manufacturing a package according to claim 1 or 2.
When there is a line L that can be drawn with a single stroke in which a straight line and a curved line are connected, and the vicinity of one end P of the line L is a straight line and the vicinity of the other end Q of the line L is a curved line. ,
A method for manufacturing a package, in which the spot is continuously moved along the line L with the one end P as a start point and the other end Q as an end point. The method for manufacturing a package according to any one of claims 1 to 3.
A method for manufacturing a package, wherein the thickness of the character line printed on the packaging material is 0.4 mm or less. The method for manufacturing a package according to any one of claims 1 to 4.
A method for manufacturing a package, wherein the font is a font of alphabets or Arabic numerals. The method for manufacturing a package according to any one of claims 1 to 5.
The packaging material further comprises a resin layer that covers the laser color-developing layer.
A method for producing a package, which is a packaging material having layers in the order of the base material layer, the laser coloring layer, and the resin layer covering the laser coloring layer. The method for manufacturing a package according to any one of claims 1 to 6.
A method for producing a package, wherein the component (X) contains particles of an inorganic metal oxyanion compound.

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