JP2018188416A - Latent image printed matter of solid formulation and imaging method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide latent image printed matter of a solid formulation having on a surface thereof a latent image that can be made visible by irradiation with ultraviolet rays having a specific wavelength band, and an imaging method therefor.SOLUTION: The latent image printed matter of a solid formulation according to the present invention is latent image printed matter of a solid formulation 10 having a latent image in at least a part of a surface thereof, characterized in that: the latent image printed matter includes at least a latent image region A in which a latent image is formed by a latent image ink layer 11 that absorbs ultraviolet rays having a wavelength band from 200 nm inclusive to 400 nm exclusive, and a non-latent image region B that reflects ultraviolet rays having at least the wavelength band and/or emits fluorescence; a difference in the gradation value between the latent image region A and the non-latent image region B when the latent image region A and the non-latent image region B are irradiated with visible light is less than five; and the difference in the gradation value between the latent image region A and the non-latent image region B when the latent image region A and the non-latent image region B are irradiated with light containing the ultraviolet rays having at least the wavelength band is five or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a latent image printed matter of a solid preparation and an imaging method thereof, and more specifically, to a latent image printed matter of a solid preparation on which a latent image that can be visualized by irradiation with ultraviolet rays in a specific wavelength range is printed. The present invention relates to an imaging method.

  In recent years, it has been increasing that a drug name is printed and displayed by a direct ink jet method on a tablet such as a medicine. In particular, the inkjet method allows variable printing (variable printing) that prints different information for each recording medium. Therefore, in addition to the drug name, the tablet lot number, tablet expiration date, and prevention of placebo are also applied to tablets. Attempts have been made to variably print security codes and the like.

  On the other hand, product information other than the drug name is information that general consumers and patients do not need to recognize. Therefore, for example, it is desirable that it is not visually recognized by general consumers or the like under visible light. Examples of inks that enable such printing include edible inks that contain riboflavins and the like, and that can change the hue only when irradiated with ultraviolet rays and can identify printed images (described below). Patent Document 1). In addition, an ink in which an edible fluorescent dye is dissolved in a solvent, and a lake pigment ink in which the fluorescent dye is insoluble in the solvent to form a lake and dispersed as a lake organic pigment in the solvent are also included.

  However, these inks have a problem that they are inferior in light resistance as compared with edible inks using an inorganic pigment such as iron oxide.

2011-2141312 gazette

  The present invention has been made in view of the above-mentioned problems, and the object thereof is a solid preparation latent image printed matter having a latent image that can be visualized by irradiation with ultraviolet rays in a specific wavelength region, and a printed product thereof. It is to provide an imaging method.

  In order to solve the above problems, the inventors of the present invention have studied the latent image printed matter of solid preparation and the imaging method thereof, and found that the above problems can be solved by adopting the following configuration. It came to complete.

  That is, the latent image printed matter of the solid preparation according to the present invention is a latent image printed matter of a solid preparation in which a latent image is provided on at least a part of the surface in order to solve the above-described problem, and has a wavelength range of 200 nm or more. At least a latent image region in which the latent image is formed by a latent image ink layer that absorbs ultraviolet rays in a range of less than 400 nm, and a non-latent image region that reflects at least ultraviolet rays in the wavelength range and / or emits fluorescence. When the visible light is irradiated to the latent image region and the non-latent image region, the difference in gradation value of the latent image region with respect to the non-latent image region is less than 5, and the latent image region and the non-latent image region have at least The difference in gradation value of the latent image region with respect to the non-latent image region when irradiated with light containing ultraviolet rays in the above wavelength range is 5 or more.

  According to the above configuration, the latent image area has a gradation value of the latent image area with respect to the non-latent image area when the latent image area and the non-latent image area are irradiated with visible light (wavelength range of 400 nm to 760 nm). The difference is less than 5. For this reason, a latent image region in which a latent image is formed by a latent image ink layer that is difficult to visually recognize under visible light irradiation is provided on the surface of the solid preparation. On the other hand, the latent image region is a region formed of a latent image ink layer that absorbs ultraviolet rays having a wavelength range of 200 nm or more and less than 400 nm. The non-latent image region is a region that reflects ultraviolet rays in the above-mentioned wavelength region and / or absorbs the ultraviolet rays and converts the wavelength to another ultraviolet region or visible light region to emit fluorescence. Further, in the latent image area, when the latent image area and the non-latent image area are irradiated with ultraviolet rays, the gradation value difference with respect to the non-latent image area becomes 5 or more. Therefore, in the latent image area, the latent image formed by the latent image ink layer can be visualized with good contrast under ultraviolet irradiation.

  In the above configuration, the surface further includes another non-latent image region in which a visible image is formed by the visible ink layer that absorbs the visible light, and the non-latent image region and the other non-latent image region are provided. It is preferable that the difference in gradation value of the other non-latent image area with respect to the non-latent image area when the visible light is irradiated to the image area is 5 or more.

  According to the above configuration, the other non-latent image area is an area where a visible image is formed by a visible ink layer that absorbs visible light, and the non-latent image area and the other non-latent image area are irradiated with visible light. In this case, the gradation value difference is 5 or more with respect to the non-latent image area. Therefore, a visible image made of a visible ink layer can be viewed with good contrast under visible light irradiation. On the other hand, the latent image formed by the latent image ink layer is difficult to view under irradiation with visible light, but can be viewed with good contrast under irradiation with ultraviolet light in the above-mentioned wavelength range. Therefore, with the above configuration, information can be recorded on the surface of the solid preparation as a latent image or a visible image according to the content of the information and the like, and the degree of freedom of the information recording method can be improved.

  Further, in the above configuration, the visible ink layer is a layer that transmits or reflects ultraviolet rays in the wavelength range, and irradiates the non-latent image region and other non-latent image regions with light containing ultraviolet rays in the wavelength range. In this case, it is preferable that the difference between the gradation values of the other non-latent image areas and the other non-latent image areas is less than 5.

  According to said structure, the visible image which was visible under irradiation of visible light can be made difficult to visually recognize under irradiation of the light containing an ultraviolet-ray. On the other hand, the latent image is difficult to visually recognize under irradiation of visible light, but becomes visible by visualization under irradiation of light containing ultraviolet rays. Therefore, the visible image and the latent image can be reversed by changing the wavelength range of the light to be irradiated. As a result, even when the area of the printable region on the solid preparation is small, more information can be recorded on the surface of the solid preparation.

  In the above configuration, the latent image ink layer preferably includes at least titanium oxide particles as a pigment. By including at least titanium oxide particles as a pigment in the latent image ink layer, the latent image ink layer can be made to exhibit good light absorption for ultraviolet rays. In addition, since titanium oxide conforms to the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law, it has low biological harm. As a result, a latent image can be directly printed on a solid preparation such as a tablet of a medicine or food. Furthermore, the light resistance can be improved as compared with an ink layer using a dye.

  In the above-described configuration, it is preferable that the latent image ink layer has a light transmitting property or a light reflecting property with respect to visible light. Since the latent image ink layer has a light-transmitting property with respect to visible light, when the latent image region and the non-latent image region are irradiated with visible light, the difference in the gradation value of the latent image region with respect to the non-latent image region is further increased. Can be reduced. As a result, the distinguishability of the latent image area under visible light irradiation can be further reduced. In addition, for example, when the non-latent image region reflects at least a part of visible light, the latent image ink layer has light reflectivity, so that the distinguishability under visible light irradiation may be reduced. it can.

  In order to solve the above problems, an imaging method of a solid preparation latent image printed matter according to the present invention is an imaging method of a solid preparation latent image printed matter provided with a latent image on at least a part of a surface thereof. The solid preparation is provided with a latent image ink layer that absorbs ultraviolet rays having a wavelength range of 200 nm or more and less than 400 nm, and the latent image region in which the latent image is formed by the latent image ink layer, and at least ultraviolet rays in the wavelength range. A latent image area that has at least a non-latent image area that reflects light and / or emits fluorescence, and the latent image area and the non-latent image area are irradiated with visible light. The difference between the values is less than 5, and the difference in the gradation value of the latent image region with respect to the non-latent image region is 5 or more when the latent image region and the non-latent image region are irradiated with light containing ultraviolet rays in the wavelength region. Less in the latent image area and the non-latent image area. And a visualization step of irradiating irradiation light including ultraviolet rays in the wavelength range to visualize the latent image in the latent image region, reflected light in which the irradiation light is reflected by the non-latent image region, and And / or an imaging step of receiving fluorescence generated in the non-latent image region and imaging the latent image region and the non-latent image region visualized in the visualization step.

  According to the above configuration, the surface of the solid preparation to be imaged is provided with a latent image region having a gradation value difference of less than 5 with respect to the non-latent image region under visible light irradiation. Therefore, the latent image region enables formation of a latent image that is difficult to visually recognize under irradiation with visible light. The latent image region is a region that absorbs ultraviolet rays having a wavelength range of 200 nm or more and less than 400 nm. On the other hand, the non-latent image region is a region that reflects ultraviolet rays in the above-described wavelength region and / or emits fluorescence. In the latent image area, when the latent image area and the non-latent image area are irradiated with light including ultraviolet rays in the wavelength range, the difference in gradation value with respect to the non-latent image area is 5 or more. It is configured. Therefore, in the above-described configuration, the latent image region can be visualized with a good contrast by irradiating the latent image region and the non-latent image region with irradiation light including at least the ultraviolet light in the wavelength range. Imaging step). In addition, in the above configuration, the reflected light reflected by the non-latent image region and / or the fluorescence generated in the non-latent image region is received, and the latent image region and the non-latent image are visualized. An image area is imaged (imaging process). Thus, for example, for the purpose of preventing the manufacture of counterfeit products, a latent image can be easily formed by irradiating ultraviolet rays in the above-mentioned wavelength range onto a printed product of a solid preparation formed with product information as a latent image. The latent image can be visualized and the latent image can be discriminated and inspected.

  In the above configuration, the visualization step is preferably a step using only ultraviolet rays having a wavelength range of 200 nm or more and less than 400 nm as the irradiation light. Since the latent image ink layer absorbs ultraviolet rays having a wavelength range of 200 nm or more and less than 400 nm, the irradiation light used in the visualization process is limited to ultraviolet rays in the wavelength range, so that the non-latent image region can be used. The difference in the gradation value of the latent image region can be further increased, and the image can be visualized with better contrast.

  In the above configuration, at least a part of the wavelength range of the ultraviolet light included in the irradiation light in the visualization step and the wavelength range of the reflected light and / or fluorescence received in the imaging step are included. It is preferable to overlap. As a result, the amount of received light in the imaging process is increased, and the latent image area and the non-latent image area can be imaged with good contrast.

  In the above configuration, the solid preparation further includes another non-latent image region in which a visible image is formed by the visible ink layer that absorbs the visible light, and the non-latent image region and the other non-latent image. The difference in gradation value of the other non-latent image region with respect to the non-latent image region when the region is irradiated with visible light is 5 or more, and the imaging step is a step of imaging the other non-latent image region. be able to.

  According to the said structure, what formed the visible image further by the visible ink layer which absorbs visible light on the surface of a solid formulation can also be made into an imaging object. When the visible ink layer is an ink layer that is visible even under irradiation of ultraviolet rays in the above wavelength range, for example, other non-latent image areas provided with the visible ink layer are also imaged in the imaging process. This makes it possible to inspect the visible ink layer.

  Further, in the above configuration, the visible ink layer is a layer that transmits or reflects ultraviolet rays in the wavelength range, and irradiates the non-latent image region and other non-latent image regions with light containing ultraviolet rays in the wavelength range. The difference in the gradation value of the other non-latent image area with respect to the non-latent image area is less than 5, and the visualization step includes irradiating the other non-latent image area with at least ultraviolet rays in the wavelength range. It is a step of forming a visible image of the other non-latent image region by irradiating light, and the imaging step also picks up other non-latent image regions latent imaged in the visualization step. It is preferable that it is a process to perform.

  According to the above configuration, the other non-latent image area has a gradation value difference with respect to the non-latent image area under irradiation of light containing the ultraviolet light by forming a visible ink layer that transmits or reflects the ultraviolet light in the wavelength range. Is less than 5. For this reason, other non-latent image areas can be formed into latent images in the visualization step, which makes it difficult to visually recognize them. As a result, in the imaging process, only the latent image visualized in the visualization process can be imaged, and the discrimination or inspection of the latent image is prevented from being hindered by the visible image. Can do.

  In the above configuration, it is preferable to use a solid preparation in which the latent image ink layer contains at least titanium oxide particles as a pigment. As a result, the latent image ink layer expresses good light absorptivity with respect to ultraviolet rays. Therefore, when the latent image region and the non-latent image region are irradiated with irradiation light including at least ultraviolet rays having a wavelength region of 200 nm or more and less than 400 nm, The latent image region can be visualized under ultraviolet irradiation. In addition, since titanium oxide conforms to the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law, it has low biological harm. As a result, a latent image can be directly printed on a solid preparation such as a tablet of a medicine or food. Furthermore, the light resistance can be improved as compared with an ink layer using a dye.

  In the above configuration, it is preferable that the latent image ink layer has a light-transmitting property or a light-reflecting property with respect to visible light. Since the latent image ink layer has a light-transmitting property with respect to visible light, when the latent image region and the non-latent image region are irradiated with visible light, the difference in the gradation value of the latent image region with respect to the non-latent image region is further increased. Can be reduced. As a result, the distinguishability of the latent image area under visible light irradiation can be further reduced. In addition, for example, when the non-latent image region reflects at least a part of visible light, the latent image ink layer has light reflectivity, so that the distinguishability under visible light irradiation may be reduced. it can.

  According to the latent image printed matter of the solid preparation according to the present invention, the latent image region in which the latent image is formed by the latent image ink layer is non-visible when the latent image region and the non-latent image region are irradiated with visible light. The difference between the gradation values of the latent image area and the latent image area is less than 5. Therefore, in the latent image printed matter of the present invention, it is difficult to visually recognize (identify) the latent image under visible light irradiation. The latent image region is a region where a latent image is formed by a latent image ink layer that absorbs ultraviolet rays having a wavelength range of 200 nm to less than 400 nm, and the non-latent image region reflects ultraviolet rays in the wavelength range. And / or a region emitting fluorescence. The latent image area is configured such that when the latent image area and the non-latent image area are irradiated with ultraviolet rays, the gradation value difference with respect to the non-latent image area is 5 or more. Therefore, according to the present invention, it is possible to provide a latent image printed matter of a solid preparation having a latent image that can be visualized with a good contrast by irradiation with ultraviolet rays in the above wavelength range.

  Further, according to the method for imaging a latent image printed matter of a solid preparation according to the present invention, a latent image is formed by irradiating the latent image area and the non-latent image area of the solid preparation with irradiation light including at least ultraviolet light in the above-mentioned wavelength range. After the visualization, the reflected light reflected from the non-latent image area and / or the fluorescence generated in the non-latent image area is received to capture the visualized latent image area and the non-latent image area. Is. Therefore, for example, for the purpose of preventing the manufacture of counterfeit products, the latent image can be easily visualized and imaged by irradiating ultraviolet rays in the above-mentioned wavelength range to the printed matter of the solid preparation on which product information is printed as a latent image. can do. As a result, according to the present invention, it is possible to provide an imaging method for a latent image printed matter of a solid preparation, which can easily identify and inspect a latent image provided in the solid preparation.

It is explanatory drawing which represents typically the latent image printed matter of the solid formulation which concerns on one Embodiment of this invention. It is a schematic diagram showing the outline of the imaging device used for the imaging method of the latent image printed matter of a solid formulation. It is explanatory drawing which represents typically the latent image printed matter of the solid formulation which concerns on other embodiment of this invention. It is a graph showing the absorption spectrum in the range of 190 nm-500 nm of the water-based ink composition used in Examples 1-12 and Comparative Examples 1-3. 6 is a graph showing an absorption spectrum in a range of 260 nm to 800 nm of the water-based ink composition used in Examples 13 and 14.

(Embodiment 1)
<Latent image printed matter of solid preparation>
The latent image printed matter (hereinafter referred to as “latent image printed matter”) of the solid preparation according to Embodiment 1 will be described below. FIG. 1 is an explanatory diagram schematically showing a latent image printed matter of a solid preparation according to the present embodiment.

  As shown in FIG. 1, the latent image printed matter of the present embodiment is provided with a latent image ink layer 11 on at least a part of the surface of the solid preparation 10. The latent image ink layer 11 forms a print image as a latent image. The latent image printed matter of the present embodiment has at least a latent image area A where the latent image ink layer 11 forms a latent image and a non-latent image area B where no latent image is formed.

  In the present specification, the term “solid preparation” means food preparations and pharmaceutical preparations, and examples of forms thereof include tablets or capsules such as OD tablets, plain tablets, FC tablets, dragees and the like. The solid preparation 10 may be used for pharmaceuticals or food. Examples of tablets for food use include health foods such as tablet confectionery and supplements. Of the solid preparation 10, the tablet is solid at room temperature, and for example, a tablet prepared by compressing and / or molding a tablet material containing an active ingredient into a certain shape is preferable. The shape of the tablet is not particularly limited, and any shape can be adopted. The tablet may be a pharmaceutical use tablet or a food use tablet. Examples of tablets for food use include health foods such as tablet confectionery and supplements.

  Further, in this specification, the “latent image” means an image that is difficult to identify under an environment irradiated with visible light (wavelength range: 400 nm to 760 nm) and is visualized under a specific condition. Furthermore, the “latent image printed matter” in the present specification means a latent image printed on the solid preparation 10 as a printed image. Here, the image printed as a latent image can be printed by, for example, an inkjet method using an aqueous inkjet ink described later. Inkjet printing means a system in which an aqueous inkjet ink is ejected as droplets from a fine inkjet head, and the droplets are fixed on the solid preparation 10 to form an image.

[Latent image area]
The latent image region A is a region where a latent image is formed by the latent image ink layer 11 that absorbs ultraviolet rays having a wavelength range of 200 nm or more and less than 400 nm. The wavelength range is more preferably in the range of 260 nm to 380 nm, particularly preferably in the range of 280 nm to 360 nm. In addition, the latent image ink layer 11 is preferably light transmissive to visible light. Furthermore, the latent image ink layer 11 may have light reflectivity with respect to visible light. In this case, as will be described later, for example, if the non-latent image region B reflects at least a part of visible light, a latent image can be suitably formed by the latent image ink layer 11. In the present specification, “light transmissivity” means a property of transmitting at least part of incident visible light or the like. In addition, the term “light transmission” includes not only the case where the latent image ink layer 11 is colorless but also the case where it is colored. Furthermore, “light reflectivity” in the present specification means a property of reflecting at least a part of incident visible light or the like.

  The latent image area A may be provided with a visible ink layer or a coating layer that forms an image visible under visible light. The latent image ink layer 11 has a light-transmitting property with respect to visible light, so that the visibility can be ensured even when the visible ink layer is provided below the latent image ink layer 11. it can. Details of the visible ink layer will be described later in the second embodiment. Examples of the coating layer include an overcoat layer for covering and protecting the latent image ink layer 11 and an undercoat layer.

The latent image ink layer 11 is preferably composed of a dry film of an aqueous inkjet ink (details will be described later). The dry film can be formed by printing directly on the surface of the solid preparation 10 using an inkjet water-based ink, for example, by an inkjet method. In addition, the latent image ink layer 11 preferably contains at least a component that has light absorptivity with respect to ultraviolet rays in the above wavelength range (hereinafter also referred to as “ultraviolet absorbing component”). Further, it is preferable that the ultraviolet absorbing component is uniformly contained in the latent image ink layer 11. Examples of the ultraviolet absorbing component include titanium oxide (TiO ₂ ) particles as a pigment. The thickness of the latent image ink layer 11 is not particularly limited, and can be set as necessary.

[Non-latent image area]
The non-latent image region B is a region that reflects ultraviolet light when irradiated with light containing at least ultraviolet light in the wavelength range (hereinafter referred to as “irradiation light”). Alternatively, the non-latent image region B is a region that absorbs ultraviolet rays as excitation light and emits fluorescence. The fluorescence generated in the non-latent image region B may include ultraviolet rays in the above wavelength range, light in the visible light region, and the like. Moreover, the case where the ultraviolet-ray of a wavelength different from the irradiated ultraviolet-ray generate | occur | produces as fluorescence may be included. Note that the non-latent image region B may be a region where reflection of ultraviolet rays and generation of fluorescence occur simultaneously.

  Here, “fluorescence” in this specification means that when ultraviolet rays (excitation light) in a wavelength region of 200 nm or more and less than 400 nm are irradiated, the ultraviolet rays are absorbed and converted, and ultraviolet rays having different wavelengths or visible light ( 380 nm to 760 nm). In addition, it also includes fluorescence of a component having a short decay time among afterglows emitted even after irradiation with ultraviolet rays. The decay time means the time required for transition from the start of light emission to the ground state (fluorescence disappears).

  In order for the non-latent image region B to have light reflectivity with respect to ultraviolet rays in a wavelength region of 200 nm or more and less than 400 nm, for example, the solid preparation 10 may contain a component for reflecting ultraviolet rays in the wavelength region. preferable. In this regard, for example, generally white tablets and capsules that are commercially available have the property of reflecting ultraviolet rays in the above-mentioned wavelength range, and therefore, the non-latent image region B can be formed. Even when the solid preparation 10 itself contains an ultraviolet-absorbing component such as titanium oxide, by providing the surface of the solid preparation 10 with an ultraviolet reflecting layer containing a component exhibiting light reflectivity with respect to ultraviolet rays in the above wavelength range. The non-latent image area B can be formed. Alternatively, by controlling the particle diameter of titanium oxide particles or the like contained in the latent image ink layer 11 and making the absorption wavelength of the latent image ink layer 11 with respect to ultraviolet rays different from the absorption wavelength of titanium oxide or the like contained in the solid preparation 10. It is also possible to form the non-latent image area B.

  In addition, in order for the non-latent image region B to have a property that exhibits fluorescence when irradiated with ultraviolet rays in the above wavelength range, for example, the solid preparation 10 absorbs ultraviolet rays in the wavelength range as excitation light. It is preferable that a fluorescent component that emits fluorescence is contained. Such a fluorescent component is not particularly limited as long as it has edible properties, and specific examples include riboflavin and the like. These fluorescent components can be used alone or in combination of two or more. Even when the solid preparation 10 itself contains an ultraviolet-absorbing component such as titanium oxide, a non-latent image region can be obtained by providing a fluorescent layer containing a fluorescent component with respect to the ultraviolet ray in the above wavelength range on the surface of the solid preparation 10. B can be formed. Here, “fluorescence” in the present specification means a property of emitting fluorescence. In addition, “edible” means that it consists only of substances that are approved for oral administration as pharmaceuticals or pharmaceutical additives and / or substances that are recognized as foods or food additives.

  Further, the non-latent image region B may include a case where at least a part of the visible light is reflected or absorbed under irradiation of visible light. In the non-latent image region B, a coating layer or the like may be provided.

[Difference in gradation value between latent image area and non-latent image area]
When the latent image area A and the non-latent image area B are simultaneously irradiated with visible light, the difference in the gradation value of the latent image area A with respect to the non-latent image area B is preferably less than 5. By making the difference between the gradation values less than 5, it is difficult to reduce (or identify) the latent image (latent image ink layer 11) under visible light irradiation, or it can be reduced.

  In the present specification, the “tone value” is a value representing the density of a captured image, and is obtained by converting image data into a gray scale by a simple average method, a weighted average method, an intermediate value method, or the like. This means an 8-bit gradation value (256-level value from 0 to 255). In the present specification, the “gradation value difference” means a value obtained by subtracting the average value of the gradation values of the non-latent image area B from the average value of the gradation values of the latent image area A. Further, the average value of gradation values means the average value of gradation values of a plurality of pixels in the image data of the latent image area A or the non-latent image area B.

  When the latent image area A and the non-latent image area B are simultaneously irradiated with irradiation light including at least ultraviolet rays, the difference in gradation value of the latent image area A with respect to the non-latent image area B is 5 or more, preferably 15 Above, more preferably 30 or more. By making the difference between the gradation values 5 or more, the latent image area A can be visualized and observed under ultraviolet irradiation.

  The gradation values in the latent image area A and the non-latent image area B when irradiated with irradiation light can be controlled by adjusting the light intensity of the irradiation light, for example. Specifically, by appropriately controlling the light intensity of the irradiation light, the difference between the gradation values of the latent image area A and the non-imaging area B is maximized to enable clearer imaging. For example, if the light intensity of the light source of the irradiation light is too weak and the gradation values of the latent image area A and the non-latent image area B are both small and the difference is small, increase the light intensity of the light source. This makes it possible to increase the difference in gradation values. In addition, if the light intensity of the light source is too high and the imaging is overexposed and the gradation values of the latent image area A and non-latent image area B are both large and the difference is large, the light intensity of the light source is reduced. By making it smaller, it becomes possible to increase the difference in gradation values. Further, the difference in the gradation value of the latent image area A with respect to the non-latent image area B can be controlled by an optimal combination of at least the wavelength of ultraviolet rays contained in the irradiated light in addition to the light intensity of the irradiated light. Alternatively, by adjusting the concentration of the ultraviolet absorbing component contained in the latent image ink layer 11, the ultraviolet absorbing ability in the latent image area A is improved or decreased, and the gradation value of the latent image area A relative to the non-latent image area B is increased. The difference may be controlled.

[Water-based ink for latent image]
As a constituent material of the latent image ink layer 11 forming the latent image region A, it is preferable to use edible aqueous ink for latent images in the present embodiment. The aqueous latent image ink includes an aqueous latent ink composition, and the latent aqueous ink composition includes at least a pigment composition (described in detail later) and water as a main solvent. Further, the aqueous ink composition for latent images of the present embodiment has edible properties and is suitably used for inkjet recording. Furthermore, since a pigment is used as a color material, the latent image water-based ink composition is superior in terms of color developability, light resistance, water resistance, and the like as compared with an ink composition using a dye.

  The content of the pigment composition is preferably in the range of 2% by mass to 40% by mass and more preferably in the range of 5% by mass to 30% by mass with respect to the total mass of the aqueous ink composition for latent images. By setting the content of the pigment composition to 2% by mass or more, the coloring power can be improved. On the other hand, dispersibility can be improved by setting the content of the pigment composition to 40% by mass or less.

  The latent image aqueous ink composition according to the present embodiment contains water (water as a main solvent). As the water, it is preferable to use water from which ionic impurities such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, or ultrapure water have been removed. In particular, water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria can be prevented over a long period of time. Moreover, it does not specifically limit as content of water, It can set suitably as needed.

  In the aqueous ink composition for latent images of the present embodiment, other additives may be blended. However, when used as an ink-jet ink for tablets such as pharmaceuticals, it is preferably one that conforms to standards such as the Pharmaceutical Affairs Law.

  Additives include surface tension modifiers, wetting agents (anti-drying agents), antifading agents, emulsion stabilizers, penetration enhancers, UV absorbers, preservatives, antifungal agents, pH adjusters, viscosity modifiers, dispersions Well-known additives, such as a stabilizer, a rust preventive agent, a chelating agent, are mentioned. Content of these various additives is not specifically limited, It can set suitably as needed.

  The surface tension adjusting agent is not particularly limited as long as it conforms to standards such as the Pharmaceutical Affairs Law, and specific examples include glycerin fatty acid esters and polyglycerin fatty acid esters. Examples of the glycerin fatty acid ester include decaglyceryl caprylate and decaglyceryl laurate.

  The addition amount of the surface tension adjusting agent is preferably in a range in which the surface tension of the aqueous ink composition for latent images can be adjusted to 25 to 40 mN / m, and more preferably in a range in which the surface tension can be adjusted to 27 to 36 mN / m. When the addition amount is within the above range, it is possible to ensure ejection stability at the time of printing by the inkjet method.

  The wetting agent is not particularly limited as long as it conforms to standards such as the Pharmaceutical Affairs Law, and specific examples include propylene glycol and glycerin.

  The addition amount of the wetting agent is preferably 3% by mass to 50% by mass and more preferably 10% by mass to 40% by mass with respect to the total mass of the aqueous ink composition for latent images.

  The viscosity of the latent image water-based ink composition of the present embodiment is preferably 2 mPa · s to 7 mPa · s, preferably 3 mPa · s to 5 mPa · s at the time of ink jet nozzle discharge, in consideration of the discharge stability from the ink jet nozzle. Is more preferable. By setting the viscosity of the aqueous ink composition for a latent image within the above numerical range, it is possible to suppress the occurrence of clogging at the ink jet nozzle and maintain good ejection stability, and to suppress a decrease in flying property. it can. In addition, the viscosity of the aqueous ink composition for latent images is obtained, for example, by measuring using a viscometer (trade name: VISCOMATE MODEL VM-10A, manufactured by Seconic Corporation) at a measurement temperature of 25 ° C. It is done.

  The latent image aqueous ink composition of the present embodiment can be produced by mixing the above-described components by an appropriate method. That is, for example, an additive or the like is separately added to the pigment composition dispersion and further diluted with water. Thereafter, the mixture is sufficiently stirred, and if necessary, filtration is performed to remove coarse particles and foreign matters that cause clogging. Thereby, the aqueous ink composition for latent images according to the present embodiment can be obtained.

  In addition, it does not specifically limit as a mixing method of each material, For example, it stirs and mixes by adding a material sequentially to the container provided with stirring apparatuses, such as a mechanical stirrer and a magnetic stirrer. Moreover, it does not specifically limit as a filtration method, For example, centrifugal filtration, filter filtration, etc. are employable.

  Since the latent image aqueous ink composition of the present embodiment is composed of components that meet standards such as the Pharmaceutical Affairs Law, it has edible properties and can be printed directly on the surface of tablets such as pharmaceuticals and supplements. is there. In addition, non-contact printing by an inkjet method is possible even for tablets with poor surface smoothness such as uncoated tablets and OD tablets. Furthermore, since the latent ink composition for a latent image is also excellent in light resistance, the occurrence of bleeding can be prevented even if it is directly printed on the surface of a tablet such as a pharmaceutical or a supplement.

[Pigment composition]
The pigment composition contained in the latent ink composition for a latent image is a composition of a pigment dispersion containing at least a pigment (ultraviolet absorbing component) composed of titanium oxide (TiO ₂ ) particles and sodium polyacrylate as a pigment dispersant. It is a thing. In the present embodiment, the pigment made of titanium oxide particles has a function as an ultraviolet absorbing component.

  The pigment made of titanium oxide particles is a white pigment, and has a lower specific gravity and a higher refractive index than other known white pigments. Titanium oxide pigments are also chemically and physically stable. Therefore, the pigment made of titanium oxide particles has excellent concealability and colorability, and also has excellent durability against acids, alkalis and other environments. The pigment composition of the present embodiment may contain a known pigment in addition to the pigment.

  In the present embodiment, as the titanium oxide particles, any one of anatase type (tetragonal), rutile (tetragonal) or brookite (orthorhombic) crystal structure can be used. However, from the viewpoint of improving the concealability of the printed image, titanium oxide having a rutile crystal structure is preferable. Thereby, it can prevent that a printed image is observed visually from the to-be-printed (formation) surface. In the present invention, the titanium oxide particles mean crystalline titanium oxide particles unless otherwise specified.

  The surface of the titanium oxide particles is preferably hydrophilic. This makes it possible to make the average dispersed particle size of the dispersed titanium oxide particles closer to the average primary particle size of the titanium oxide particles (details will be described later). Usually, hydroxyl groups are present on the surface of the titanium oxide particles, whereby the surface of the titanium oxide particles exhibits hydrophilicity. In the present invention, “hydrophilic” means that a functional group having an affinity for water exists on the surface of the titanium oxide particles.

  Moreover, in this invention, you may perform a hydrophilic treatment from a viewpoint of improving or maintaining the hydrophilic property of the surface of a titanium oxide particle. When the surface of the titanium oxide particles is subjected to a hydrophilic treatment, for example, a surface treatment agent of an inorganic compound and / or an organic compound can be used.

  The surface treatment agent for the inorganic compound is not particularly limited, and examples thereof include aluminum hydroxide, aluminum oxide, zirconium oxide, silica, and cerium oxide. The surface treatment agent for organic compounds is not particularly limited. For example, dimethyl polysiloxane, methyl hydrogen polysiloxane, (dimethicone / methicone) copolymer, methyl phenyl silicone, amino-modified silicone, hydrogen dimethicone, triethoxysilylethyl poly Silicone oils such as dimethylsiloxyethyl dimethicone and triethoxysilylethyl polydimethylsiloxyethylhexyl dimethicone; higher fatty acids such as stearic acid and lauric acid; trimethylolethane, pentaerythritol, tripropanolethane, ditrimethylolpropane, trimethylolpropane ethoxylate, etc. Polyhydric alcohols; alkanolamines such as triethanolamine and tripropanolamine, or their hydrochlorides or salts Derivatives such as acid salts; alkyl silanes such as caprylyl silane, decyl silane, and perfluorooctyl silane, alkyl titanates, alkyl aluminates, polyolefins, polyesters, lauroyl lysine, and other amino acids; titanium coupling agents, aluminum coupling agents, zirconium And organometallic compounds such as coupling agents. Surface treatment can be performed with at least one compound selected from these organic compounds. Moreover, you may perform a hydrophilization treatment combining an inorganic compound and an organic compound.

  Commercially available products may be used as the titanium oxide particles. Examples of such commercially available products include STR-100N (trade name, manufactured by Sakai Chemical Industry Co., Ltd., rutile type), TTO-51A (trade name). , Ishihara Sangyo Co., Ltd., rutile type), TTO-55A (trade name, Ishihara Sangyo Co., Ltd., rutile type), TTO-55A (trade name, Ishihara Sangyo Co., Ltd., rutile type), TTO-80A (product) Name, Ishihara Sangyo Co., Ltd., rutile type), MPT-140 (trade name, Ishihara Sangyo Co., Ltd., rutile type), MPT-141 (trade name, Ishihara Sangyo Co., Ltd., rutile type), MKR-1 ( Product name, Sakai Chemical Industry Co., Ltd., rutile type), KA-10 (trade name, Titanium Industry Co., Ltd., anatase type) and the like.

  When the pigment composition of the present embodiment is used for printing on the surface of tablets such as pharmaceuticals and supplements, the titanium oxide particle pigment is a standard for pharmaceutical additives, Japanese Pharmacopoeia or Food Additives Standards specified by the Pharmaceutical Affairs Law. (Hereinafter referred to as “standards of the Pharmaceutical Affairs Law”) is preferable.

  The average primary particle diameter (volume average particle diameter) of the titanium oxide particles is preferably 20 nm to 400 nm, more preferably 30 nm to 200 nm, and particularly preferably 40 nm to 100 nm. By setting the average primary particle size to 20 nm or more, it is possible to suppress the decrease in light resistance of the printed image and increase the pigment concentration, thereby improving the transparency. Also, sufficient concealment can be ensured. On the other hand, by setting the average primary particle diameter to 400 nm or less, it is possible to achieve high color and prevent sedimentation of titanium oxide particles and nozzle clogging. In general, when pigment particles having a large average primary particle size are selected, the pigment particles are sufficiently ground to enable pigment dispersion at the level of the average dispersed particle size required for printing by an inkjet method. The process time for this becomes longer. However, as described above, by setting the average primary particle size to 400 nm or less, it is possible to suppress an increase in process time.

  In the present invention, “average primary particle size” means the average particle size of primary particles, and primary particles generally refer to the smallest particles constituting a powder, and a single crystal or a crystallite close thereto is used. It is meant to include particles that are gathered and formed.

  The average primary particle diameter is an arithmetic average diameter obtained by observing titanium oxide particles with an electron microscope. In this embodiment, titanium oxide particles having a monodispersed particle size distribution are used, but the present invention is not limited to this, and titanium oxide particles having a polydispersed particle size distribution may be used. Two or more pigments having a monodispersed particle size distribution may be mixed and used.

  The shape of the titanium oxide particles is not particularly limited, and any shape such as a spherical shape, a rod shape, a needle shape, a spindle shape, or a plate shape can be used. In the present embodiment, titanium oxide particles having the same shape may be used, or two or more different shapes may be mixed and used. The average primary particle diameter in the case of rod-like, needle-like, and spindle-like particles is defined by the geometric mean value of the length (or height) of the major axis and the length (or width) of the minor axis.

  The content of the pigment directly affects the image density and affects the storage stability, viscosity, pH, etc. of the aqueous latent ink composition. That's fine. Usually, it is preferably in the range of 2% by mass to 20% by mass and more preferably in the range of 5% by mass to 15% by mass with respect to the total mass of the pigment composition. By setting the content of the pigment made of titanium oxide particles to 2% by mass or more, a decrease in image density can be suppressed. On the other hand, by setting the content of the pigment composed of titanium oxide particles to 20% by mass or less, it is possible to prevent a decrease in gloss, nozzle clogging, and a decrease in ejection stability.

  Sodium polyacrylate functions as a pigment dispersant for the pigment of the present embodiment. By adding sodium polyacrylate, the dispersibility of the pigment can be improved. Further, by using sodium polyacrylate, it is possible to suppress the generation of bubbles in the pigment composition and the latent image aqueous ink composition. As a result, the addition of an antifoaming agent can be omitted. Further, when the aqueous ink composition for latent images of the present embodiment is ejected from the ink jet head, the bubbles are not present in the aqueous ink composition for latent images, so that nozzle omission, ejection failure, open time Can also be suppressed. In addition, sodium polyacrylate conforms to the standards defined by the Pharmaceutical Affairs Law. Accordingly, sodium polyacrylate can be suitably used for printing on tablets or the like of pharmaceuticals or foods.

  The weight average molecular weight of sodium polyacrylate is 10,000 or less, preferably 1500 to 10,000, more preferably 2000 to 8000. By setting the mass average molecular weight of sodium polyacrylate to 10,000 or less, the molecular chain of sodium polyacrylate adsorbed on the surface of the titanium oxide particles is prevented from becoming excessively long. As a result, it is possible to reduce the aggregation and aggregation of the pigments made of titanium oxide particles. By setting the mass average molecular weight of sodium polyacrylate to 1500 or more, it becomes possible for sodium polyacrylate adsorbed on the surface of the titanium oxide particles to sufficiently exert a repulsive force due to steric hindrance or the like. As a result, the titanium oxide particles can be prevented from reaggregating. In addition, the mass average molecular weight of sodium polyacrylate is a value obtained by the measuring method as described in the Example mentioned later, for example.

  The content ratio of the pigment of the present embodiment and sodium polyacrylate is preferably 1: 0.05 to 1: 1.5, and preferably 1: 0.1 to 1: 1 on a mass basis. More preferred. By setting the content ratio to 1: 0.05 or more, it is possible to prevent a decrease in the dispersibility of the titanium oxide particle pigment. On the other hand, when the content ratio is set to 1: 1.5 or less, for example, when used in a latent image water-based ink composition, it is possible to prevent a decrease in ejection stability due to adhesion to the nozzle plate. it can.

  For example, when sodium polyacrylate is added to a dispersion medium described later, bubbles are relatively less likely to be generated than other conventional pigment dispersants. Therefore, the addition of an antifoaming agent can be omitted in the pigment composition of the present embodiment.

  The pigment composition according to the present embodiment includes a dispersion medium for dispersing the pigment of titanium oxide particles. Examples of the dispersion medium include water, and more specifically, pure water such as ion-exchanged water, ultrafiltrated water, reverse osmosis water, and distilled water, or those obtained by removing ionic impurities such as ultrapure water. . In particular, water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria can be prevented over a long period of time. Moreover, it is not specifically limited as content of a dispersion medium, It can set as needed suitably.

  As the dispersion medium, a mixed solution of water and a water-soluble organic solvent may be used. The water-soluble organic solvent is not particularly limited as long as it meets standards such as the Pharmaceutical Affairs Law. Specific examples include ethyl alcohol, n-butyl alcohol, isobutyl alcohol, n-propyl alcohol, isopropyl alcohol, acetone, propylene glycol, polyethylene glycol, glycerin and the like. You may use these individually by 1 type or in mixture of 2 or more types. Furthermore, the blending amount when a water-soluble organic solvent is used as the dispersion medium is not particularly limited, and can be appropriately set as necessary.

  The average dispersed particle diameter D50 of the titanium oxide particles in a dispersed state is preferably in the range of 20 nm to 500 nm, and more preferably in the range of 40 nm to 100 nm. Further, the dispersed particle diameter D99 of the pigment (99% in terms of cumulative particle size in the volume cumulative particle size distribution) is preferably 1000 nm or less, and more preferably 500 nm or less. By setting D50 to 20 nm or more, deterioration of storage stability, light resistance and ejection stability can be prevented, and a decrease in printing density can also be prevented. On the other hand, by setting D50 to 500 nm or less or D99 to 1000 nm or less, separation, sedimentation and aggregation of the pigment can be prevented and preservation stability can be maintained. The average dispersed particle diameters D50 and D99 of the pigment are values measured by a dynamic light scattering method using Microtrac UPA-EX150 (trade name, manufactured by Nikkiso Co., Ltd.).

  The ratio of the average primary particle diameter of the titanium oxide particles and the average dispersed particle diameter D50 of the titanium oxide particles dispersed in the dispersion medium is preferably in the range of 1: 0.3 to 1: 3. In this embodiment, by using sodium polyacrylate having a mass average molecular weight of 10,000 or less as a pigment dispersant for the pigment of titanium oxide particles, the average dispersed particle size of the titanium oxide particles is changed to the average primary particle size of the titanium oxide particles. The level can be almost the same as the particle diameter. As a result, for example, when titanium oxide particles having a small average primary particle diameter are used, a pigment composition having a small average dispersed particle diameter D50 can be obtained, and separation, sedimentation and aggregation of the pigment can be prevented, and storage stability can be obtained. Maintains sex. The ratio of the average primary particle diameter of the titanium oxide particles to the average dispersed particle diameter D50 of the titanium oxide particles is more preferably 1: 0.5 to 1: 2.5, and particularly preferably 1: 0.8 to 1. : 2.

  In the method for producing the pigment composition of the present embodiment, the mixing method and the order of addition of the pigment made of titanium oxide particles, sodium polyacrylate, the dispersion medium, and other additives blended as necessary are not particularly limited. For example, a pigment of titanium oxide particles, sodium polyacrylate, water as a dispersion medium, and the like may be mixed at a time, and the mixed solution may be subjected to a dispersion treatment using an ordinary disperser.

  However, in the present embodiment, by using sodium polyacrylate as a pigment dispersant, it is possible to suppress the generation of bubbles in the pigment composition and the latent image aqueous ink composition containing the pigment composition. Can do. Therefore, the defoaming step for reducing or eliminating the bubbles can be omitted, and the production efficiency can be improved. In addition, since the inclusion of an antifoaming agent can be omitted, the production of a pigment composition and a latent ink aqueous ink composition that meet standards such as the Pharmaceutical Affairs Law becomes easier.

  The dispersion time in the dispersion process is not particularly limited, and can be set as necessary. The disperser used in the pigment dispersion treatment is not particularly limited as long as it is a commonly used disperser. Specific examples include a ball mill, a roll mill, a sand mill, a bead mill, a paint shaker, and a nanomizer.

  The pigment composition of the present embodiment includes not only the form of a latent image aqueous ink composition as a final product but also the form of a pigment dispersion for preparing the latent image aqueous ink composition. It is.

<Printing method of solid image latent image print>
The method for printing a latent image printed matter of a solid preparation according to the present embodiment includes at least a latent image printing step of printing a latent image on the surface of the solid preparation.

  Examples of the method for printing a latent image (latent image ink layer 11) on the surface of the solid preparation 10 include an inkjet recording method using a latent image aqueous ink composed of a latent image aqueous ink composition. As described above, since the latent ink composition for latent images of the present embodiment is excellent in light resistance and does not cause bleeding, product information of the solid preparation 10 can be printed as a latent image that can be visualized. .

  The ink jet recording method for the surface of the tablet is not particularly limited. Specifically, for example, the latent ink aqueous ink composition can be discharged as droplets from a fine nozzle, and the droplets can be adhered to the tablet surface. The discharge method is not particularly limited, and for example, a known method such as a continuous injection type (charge control type, spray type, etc.), an on-demand type (piezo type, thermal type, electrostatic suction type, etc.) can be employed. .

  In addition, the latent image printing step may include a drying step of drying the latent image aqueous ink droplets attached to the surface of the solid preparation 10. It does not specifically limit as a drying method, In addition to hot air drying, natural drying etc. can be performed. Also, the drying conditions such as drying time and drying temperature are not particularly limited, and can be appropriately set according to the discharge amount of the droplets, the type of the latent ink composition for a latent image, and the like.

<Imaging Method for Printed Latent Image of Solid Formulation>
Next, the imaging method of the latent image printed matter of the solid preparation according to the present embodiment will be described below.
The imaging method according to the present embodiment includes at least a visualization step that visualizes a latent image and an imaging step that captures the latent image visualized in the visualization step.

  The visualization step is performed by irradiating the latent image area A and the non-latent image area B with irradiation light including at least ultraviolet rays. By the irradiation of the irradiation light, the latent image ink layer 11 in the latent image area A absorbs ultraviolet rays. On the other hand, the non-latent image region B reflects ultraviolet rays and / or emits fluorescence. Thereby, in the latent image area A, the difference in gradation value with respect to the non-latent image area B is 5 or more, and the latent image formed by the latent image ink layer 11 can be visualized.

The wavelength range of the ultraviolet rays is in the range of 200 nm or more and less than 400 nm, and can be appropriately set according to the type of the ultraviolet absorbing component contained in the latent image ink layer 11. Further, the light intensity (μW / cm ² ) at the time of emitting the irradiation light is appropriately set according to the type of the ultraviolet absorbing component, the content in the latent image ink layer 11, the degree of ultraviolet light absorption, and the like. Can do. For example, when titanium oxide is used as the ultraviolet absorbing component, the light intensity is in the range of 4000 μW / cm ^{2 to} 35000 μW / cm ² , more preferably 5000 μW / cm ^{2 to} 30000 μW / cm ² , and particularly preferably 10,000 μW / cm ^2. ˜20000 μW / cm ² . Furthermore, the irradiation angle with respect to the solid formulation 10 of irradiation light is not specifically limited, It can set suitably. The “irradiation angle” means an angle formed by the irradiation direction of irradiation light irradiated on the solid preparation 10 and a horizontal plane on which the solid preparation 10 is placed.

  In the imaging step, the reflected light reflected by the non-latent image region B and / or the fluorescence generated in the non-latent image region B (hereinafter referred to as “reflected light”) are received and visualized. This is performed by imaging the latent image area and the non-latent image area that have been visualized in (1). The light receiving conditions are preferably set so as to show the maximum sensitivity with respect to the wavelength range of the irradiated light. Specifically, it is preferable to set the light receiving conditions so that the wavelength range of light that can be received is at least partially matched with the wavelength range of irradiation light, and more preferably, the wavelength range of light that can be received is less than 400 nm. Set. As a result, the amount of received light is increased, and the latent image area A and the non-latent image area B can be imaged with good contrast. When the light receiving sensitivity is low or absent with respect to a wavelength region such as reflected light, it may be difficult to image the visualized latent image region A and non-latent image region B.

  The light receiving angle when receiving reflected light or the like is not particularly limited, and may be set as appropriate so that the amount of received light such as reflected light is maximized. The “light receiving angle” means an angle formed by a light ray that maximizes the amount of light such as reflected light in the non-latent image region B and a normal line to the horizontal plane.

  In the latent image printed matter imaging method of the present embodiment, it is possible to further perform an inspection step for confirming whether there is a printing defect in the latent image ink layer 11 after the imaging step. In this case, the inspection method for confirming whether or not there is a printing defect is not particularly limited, and a conventionally known method can be employed.

<Imaging device for latent image printed matter of solid preparation>
Next, an imaging apparatus used for the latent image printed matter imaging method will be described with reference to FIG. FIG. 2 is a schematic diagram illustrating an outline of an imaging apparatus used in the imaging method.

  As shown in FIG. 2, the imaging device of the present embodiment includes at least a light irradiation unit 21 for irradiating the solid preparation 10 with irradiation light and an imaging unit 22 for imaging the solid preparation 10.

  The light irradiation means 21 is not particularly limited as long as it can irradiate light including ultraviolet rays having a wavelength range of 200 nm to less than 400 nm. For example, various well-known things, such as a black light, a mercury lamp, a metal halide lamp, a xenon lamp, LED, are mentioned.

  Moreover, when the light irradiation means 21 irradiates light containing visible light etc., and wants to irradiate only the ultraviolet-ray of the said wavelength range with respect to the solid formulation 10, the light (for example, wavelength range other than the said wavelength range) , Visible light, infrared light, etc.) may be irradiated through the first optical filter 23 that blocks or attenuates. Alternatively, the light irradiating means 21 having such a built-in first optical filter 23 may be used.

  The imaging means 22 receives reflected light and fluorescence reflected by the non-latent image area B by irradiation of irradiation light, and captures images of the latent image area A and the non-latent image area B. More specifically, the imaging unit 22 may be a conventionally known ultraviolet camera or the like.

  Further, when it is desired to control the wavelength of light received by the image pickup means 22, the image pickup means 22 may receive light via a second optical filter 24 such as a wavelength filter. Thereby, for example, the wavelength range of the received light can be matched with the wavelength range of the irradiation light. It does not specifically limit as the 2nd optical filter 24, For example, the conventionally well-known wavelength filter etc. which can interrupt | block or attenuate visible light, infrared light, etc. are mentioned. Further, as the image pickup means 22, a device incorporating such a second optical filter 24 may be used.

(Embodiment 2)
<Latent image printed matter of solid preparation>
A latent image printed matter of the solid preparation according to Embodiment 2 will be described below. FIG. 3 is an explanatory view schematically showing a latent image printed matter of the solid preparation according to the present embodiment. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 3, the latent image printed material according to the present embodiment further includes another non-latent image region C in which a visible image is formed by the visible ink layer 12 as compared with the latent image printed material according to the first embodiment. Different points are provided. The visible ink layer 12 is provided on the surface of the solid preparation 10, and the latent image ink layer 11 is laminated on the visible ink layer 12 so as to partially overlap.

  Here, in this specification, the “visible image” means an image that can be identified in an environment irradiated with visible light (wavelength range: 400 nm to 760 nm). Furthermore, the visible image may include an image that becomes a latent image in an environment irradiated with ultraviolet rays having a wavelength range of 200 nm or more and less than 400 nm and is difficult to identify. An image printed as a visible image can be printed by, for example, an inkjet method using an aqueous inkjet ink described below.

[Other non-latent image areas]
The other non-latent image region C is a region where a visible image is formed by the visible ink layer 12 that absorbs at least visible light (wavelength range of 400 nm to 760 nm).

  When the latent image ink layer 11 and the visible ink layer 12 are laminated in a state where at least part of them overlaps as in the present embodiment, the latent image ink layer 11 is preferably laminated on the visible ink layer 12. As a result, when the latent image ink layer 11 has a light-transmitting property with respect to visible light, visible light passes through the latent image ink layer 11, so that the visible image is not obstructed by the latent image ink layer 11. Identification is possible. As a result, even when the area of the printable region is small, more information can be recorded on the surface of the solid preparation 10. In addition, when the latent image is visualized, it is possible to irradiate the entire area of the latent image ink layer 11 with ultraviolet rays. As a result, the latent image can be visualized in a good state.

  The visible ink layer 12 may be a layer that absorbs ultraviolet rays having a wavelength range of 200 nm or more and less than 400 nm, but is preferably a layer that transmits or reflects. By doing so, since the non-latent image region B is a region that reflects ultraviolet rays and / or emits fluorescence, the visible image formed by the visible ink layer 12 upon irradiation with ultraviolet rays is converted into a latent image. Can be As a result, when the latent image in the latent image area A is visualized, it can be avoided that the latent image is visually recognized, and the visibility of the visualized latent image can be improved.

  The visible ink layer 12 is preferably made of a dry film of a visible image water-based ink described later. The dry film can be formed by printing directly on the surface of the solid preparation 10 by using, for example, an ink jet method or the like, using a water-based ink for visible images. The visible ink layer 12 preferably contains at least a component that absorbs visible light (hereinafter sometimes referred to as “visible light absorbing component”). Furthermore, it is preferable that the visible light absorbing component is uniformly contained in the visible ink layer 12. Examples of the visible light absorbing component include dyes and pigments (details will be described later). Note that the thickness of the visible ink layer 12 is not particularly limited, and can be set as necessary.

  The present embodiment is not limited to the case where the latent image ink layer 11 is laminated on the visible ink layer 12. For example, the latent image ink layer 11 and the visible ink layer 12 can be provided in different regions on the surface of the solid preparation 10, respectively. As a result, the visible ink layer 12 is a layer that absorbs ultraviolet rays in the above-mentioned wavelength range, and even when it is not formed into a latent image under the irradiation of the ultraviolet rays, the visible ink layer 12 is visually recognized overlapping with the visualized latent image. It is possible to prevent the visibility of both the latent image and the visible image from being lowered. The visible ink layer 11 may be laminated on the latent image ink layer 11.

[Difference in gradation value between non-latent image area and other non-latent image areas]
When the non-latent image region B and the other non-latent image region C are simultaneously irradiated with visible light, the difference in gradation value of the other non-latent image region C with respect to the non-latent image region B is 5 or more, preferably 15 or more, more preferably 30 or more. By making the difference between the gradation values 5 or more, the visible image (visible ink layer 12) can be visually recognized (or identified) under visible light irradiation.

  The “gradation value” in the present embodiment is the same as that described in the first embodiment. The “gradation value difference” in the present embodiment is a value obtained by subtracting the average value of the gradation values of the non-latent image area B from the average value of the gradation values of the other non-latent image area C. means. Further, the average value of gradation values means the average value of gradation values of a plurality of pixels in the image data of another non-latent image area C or non-latent image area B.

  Suitable visibility of a visible image under visible light irradiation can be controlled by a combination of a peak wavelength at which the visible light absorption component contained in the visible ink layer 12 absorbs the visible light most and a wavelength of visible light to be irradiated. is there. Alternatively, by adjusting the concentration of the visible light absorbing component contained in the visible ink layer 12, the visible light absorbing ability of the visible ink layer 12 is improved, and the gradation of the other non-latent image region C with respect to the non-latent image region B is improved. You may control so that the difference of a value may be maximized.

  When the non-latent image region B and the other non-latent image region C are simultaneously irradiated with irradiation light including at least ultraviolet rays, the difference in gradation value of the other non-latent image region C with respect to the non-latent image region B is less than 5 It is preferable that By making the difference between the gradation values less than 5, it is difficult to reduce (or identify) the visible image (visible ink layer 12) under ultraviolet irradiation, or it can be reduced. That is, this makes it possible to form a latent image of a visible image under irradiation with light containing ultraviolet rays in the above wavelength range. In order to make a visible image a latent image, it is possible to make the visible ink layer 12 a layer that transmits or reflects ultraviolet rays.

[Water-based ink for visible images]
As a constituent material of the visible ink layer 12 that forms the other non-latent image region C, it is preferable to use an edible water-based visible image ink in the present embodiment. The water-based ink for visible images includes a water-based ink composition for visible images.

  When a dye is used as the colorant (visible light absorbing component) in the visible-image aqueous ink composition, the visible-image aqueous ink composition contains at least one dye and water as a main solvent.

  It does not specifically limit as dye, A conventionally well-known edible synthetic pigment | dye (synthetic tar pigment | dye), an edible natural pigment | dye, etc. are mentioned.

  Examples of the edible synthetic pigment include at least one selected from the group consisting of azo dyes, triphenylmethane dyes, xanthene dyes, and indigoid dyes. Furthermore, the azo dye is not particularly limited, and examples thereof include at least one selected from the group consisting of Red No. 2, Red No. 102, Red No. 40, Yellow No. 4, and Yellow No. 5. It does not specifically limit as a triphenylmethane type dye, For example, at least any one of blue No. 1 or green No. 3 is mentioned. The xanthene dye is not particularly limited, and examples thereof include at least one selected from the group consisting of Red No. 3, Red No. 104, Red No. 105 and Red No. 106. Examples of indigoid dyes include Blue No. 2.

  Moreover, as an edible natural pigment | dye, at least 1 sort (s) chosen from the group which consists of a cochineal pigment | dye, copper chlorophyllin sodium, a cacao pigment | dye, and a caramel pigment | dye is mentioned.

  Furthermore, in the present embodiment, lake pigments obtained by lake- ing the dyes exemplified above with a known lake agent can also be used.

  These dyes can be used alone or in admixture of two or more as required. These dyes and the like are compliant with the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law.

  The dyes exemplified above exhibit light absorptivity with respect to visible light. Moreover, these dyes show light transmittance with respect to ultraviolet rays in a wavelength region of 200 nm or more and less than 400 nm. Therefore, when these dyes are used as the constituent material of the visible ink layer 12, they are visible under irradiation with visible light, and the non-latent image region B reflects the ultraviolet light under irradiation with ultraviolet light in the above wavelength range. In addition, since the region emits fluorescence, the visible ink layer 12 that makes it difficult to visually recognize by forming a latent image can be formed. In addition, each dye illustrated above is independent, or can use 2 or more types together. Moreover, it is preferable that all of these dyes conform to the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law.

  The content of the dye is not particularly limited, but is usually in the range of 0.2% by mass to 20% by mass, preferably 1% by mass to 10% by mass with respect to the total mass of the visible image water-based ink composition. It is.

  The aqueous ink composition for visible images of the present embodiment may contain a surface tension adjusting agent. The surface tension adjusting agent is not particularly limited as long as it conforms to standards such as the Pharmaceutical Affairs Law. Specifically, for example, polyglycerin fatty acid ester, caprylic acid decaglyceryl, lauric acid hexaglycerin ester, oleic acid hexaglycerin. Examples include esters. You may use these individually by 1 type or in mixture of 2 or more types. The content of the surface tension adjusting agent is not particularly limited, but is usually in the range of 0.5% by mass to 5% by mass with respect to the total mass of the visible ink aqueous ink composition.

  Further, the water-based ink composition for visible images of the present embodiment may contain a wetting agent. The wetting agent is not particularly limited as long as it meets standards such as the Pharmaceutical Affairs Law, and specific examples include propylene glycol and glycerin. The addition amount of the wetting agent is not particularly limited, but is usually in the range of 20% by mass to 50% by mass with respect to the total mass of the aqueous ink composition.

  In the visible image water-based ink composition of the present embodiment, other additives may be blended. However, when used as an ink-jet ink for solid preparations such as pharmaceuticals, it is preferably one that complies with the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law. Examples of the additive include water-soluble resins, organic amines, surfactants, pH adjusters, chelating agents, preservatives, viscosity adjusters, and antifoaming agents. The content of these additives is not particularly limited, and can be appropriately set as necessary.

  Further, in the visible image water-based ink composition of the present embodiment, a pigment can be used as a colorant (visible light absorbing component). In this case, the water-based ink composition for visible images includes at least a pigment composition and water as a main solvent.

  The pigment composition is a composition containing at least a pigment and a pigment dispersant. The content of the pigment composition is not particularly limited, but is usually in the range of 0.5% by mass to 20% by mass in terms of pigment with respect to the total mass of the aqueous ink composition for visible images.

  Examples of the pigment include carbon black and black iron oxide. These pigments have a light absorption property for visible light. Therefore, when the non-latent image region B reflects visible light, the gradation value of the other non-latent image region C with respect to the non-latent image region B can be obtained by using these pigments as the constituent material of the visible ink layer 12. The difference can be increased. In addition, these pigments have light absorptivity with respect to ultraviolet rays having a wavelength range of 200 nm or more and less than 400 nm. Therefore, when the latent image composed of the latent image ink layer 11 is visualized by irradiating ultraviolet rays, the visible image composed of the visible ink layer 12 is also formed on the surface of the solid preparation 10 together with the visualized latent image. Visible. Therefore, when these pigments are used, it is preferable that the visualized latent image is sufficiently visible (discriminated). Specifically, the visible ink layer 12 may be printed in a region different from the latent image ink layer 11, or the pigment concentration may be reduced within a range in which visibility at the time of visible light irradiation is sufficiently secured. it can. In addition, each pigment illustrated above is independent, or can use 2 or more types together. Moreover, it is preferable that all of these pigments conform to the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives defined by the Pharmaceutical Affairs Law.

  The content of the pigment is not particularly limited, and can be appropriately set in consideration of storage stability, viscosity, and image density of the aqueous ink composition for visible images. Usually, the content of the pigment is in the range of 0.5% by mass to 40% by mass with respect to the total mass of the pigment composition.

  As the pigment dispersant, those usually used for water-based ink compositions for ink jet can be used. Specific examples include nonionic surfactants and anionic surfactants. Nonionic surfactants include, for example, polyoxyethylene hydrogenated castor oil, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene behenyl ether, and other polyoxyethylene Examples include ethylene alkyl ether, polysorbate, decaglyceryl oleate and the like. Examples of the anionic surfactant include sodium polyacrylate. These may be used alone or in admixture of two or more. However, when the pigment composition of this embodiment is used for printing on the surface of tablets such as pharmaceuticals and foods, it must conform to the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law. It is preferable to use it.

  Further, the pigment composition includes a dispersion medium for dispersing the pigment, and the same dispersion medium as that used in the pigment composition in the aqueous ink composition for latent images of Embodiment 1 is employed. can do. Therefore, the description of the details is omitted.

  The water-based ink composition for visible images according to the present embodiment contains water (water as a main solvent). As the water, it is preferable to use water from which ionic impurities such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, or ultrapure water have been removed. It does not specifically limit as content of water, It can set suitably as needed.

  In the visible image aqueous ink composition of the present embodiment, a surface tension adjuster, a wetting agent (anti-drying agent), an anti-fading agent, an emulsion stabilizer, a penetration accelerator, an ultraviolet absorber, an antiseptic, and an antifungal agent. In addition, additives such as a pH adjuster, a viscosity adjuster, a dispersion stabilizer, a rust inhibitor, and a chelating agent may be blended. However, when used as an ink-jet ink for tablets such as pharmaceuticals, it is preferably one that conforms to standards such as the Pharmaceutical Affairs Law.

  The surface tension adjusting agent is not particularly limited as long as it conforms to standards such as the Pharmaceutical Affairs Law, and specific examples include glycerin fatty acid esters and polyglycerin fatty acid esters. Examples of the glycerin fatty acid ester include decaglyceryl caprylate and decaglyceryl laurate. The addition amount of the surface tension adjusting agent is not particularly limited, but is usually set so that the surface tension of the latent image water-based ink composition can be adjusted in a range of 25 to 40 mN / m.

  The wetting agent is not particularly limited as long as it conforms to standards such as the Pharmaceutical Affairs Law, and specific examples include propylene glycol and glycerin. The addition amount of the wetting agent is not particularly limited, but is usually in the range of 3% by mass to 50% by mass with respect to the total mass of the visible image water-based ink composition.

  The method for producing the pigment composition and the aqueous ink composition for visible images is not particularly limited, and conventionally known methods can be employed.

<Printing method of solid image latent image print>
The method for printing a latent image printed matter of a solid preparation according to the present embodiment includes a visible image printing process for printing a visible image on the surface of the solid preparation, and a latent image printing process for printing a latent image on the surface of the solid preparation. At least.

  The visible image printing step is a step of forming a visible image by printing the visible ink layer 12 on the surface of the solid preparation 10 using the visible image aqueous ink. A method for forming the visible ink layer 12 is not particularly limited, but printing by an inkjet method is preferable. More specifically, the visible ink layer 12 is printed by the inkjet method by ejecting the visible image water-based ink as droplets from a fine nozzle and attaching the droplets onto the solid preparation 10. There are no particular limitations on the method for ejecting the water-based ink for visible images. For example, a known method such as a continuous ejection type (charge control type, spray type, etc.), on-demand type (piezo type, thermal type, electrostatic suction type, etc.) Can be adopted. Printing conditions such as ink droplet ejection amount and printing speed are not particularly limited, and can be set as necessary.

  In addition, the visible image printing step can include a drying step of drying the droplets of the visible image water-based ink attached to the surface of the solid preparation 10. It does not specifically limit as a drying method, In addition to hot air drying, natural drying etc. can be performed. Also, the drying conditions such as drying time and drying temperature are not particularly limited, and can be appropriately set according to the discharge amount of the droplets, the type of the visible ink aqueous ink composition, and the like.

  The latent image printing step is a step of forming a latent image on the surface of the solid preparation 10 by printing the latent image ink layer 11 using the latent image water-based ink. Although the method for forming the latent image ink layer 11 is not particularly limited, printing by an ink jet method is preferable as in the case of the visible image printing step. The printing of the latent image ink layer 11 by the ink jet method is the same as that in the visible image printing step except that the latent image water-based ink is used. In addition, the latent image printing step may include a drying step of drying the latent image aqueous ink droplets attached to the surface of the solid preparation 10. The drying method and drying conditions are the same as those in the visible image printing process.

  Here, when the printing area of the visible image (other non-latent image area C) and the printing area of the latent image (latent image area A) are different from each other on the surface of the solid preparation 10, the visible image printing process and the latent image printing process are performed. The order of the image printing process is not particularly limited. For example, when the latent image printing process is performed before the visible image printing process, the latent image may be printed in an area different from the scheduled printing area of the visible image. On the other hand, when at least a part of the visible image printing area and the latent image printing area are overlapped on the surface of the solid preparation 10 as in the present embodiment, first, after the visible image is printed in the visible image printing process. The latent image is preferably printed in the latent image printing step. As a result, in the region where the visible image and the latent image overlap, the latent image ink layer 11 can be laminated on the visible ink layer 12, and ultraviolet light is visualized when the latent image ink layer 11 is visualized. Can be applied to the entire area of the latent image ink layer 11.

<Imaging Method and Imaging Device for Printed Latent Image of Solid Formulation>
Next, the imaging method of the latent image printed matter of the solid preparation according to the present embodiment will be described below.
As in the case of the first embodiment, the method for imaging the latent image printed matter of the solid preparation of the present embodiment is a visualization step for developing a latent image, and the latent image visualized in the visualization step. An imaging step of capturing an image.

  The visualization step is performed by irradiating the latent image area A, the non-latent image area B, and the other non-latent image area C with irradiation light including at least ultraviolet rays. By the irradiation of the irradiation light, the latent image ink layer 11 in the latent image region A absorbs ultraviolet rays, and the non-latent image region B reflects the ultraviolet rays and / or emits fluorescence. On the other hand, in the case where the visible ink layer 12 is a layer that transmits or reflects ultraviolet rays, the difference in gradation value with respect to the non-latent image region B is less than 5 in the other non-latent image region C, and the visible ink layer 12 forms the visible ink layer 12. An image can be converted into a latent image. However, in the case where the visible ink layer 12 is a layer that absorbs ultraviolet rays, like the latent image ink layer 11, the difference in gradation value between the other non-latent image region C and the non-latent image region B is 5 or more. The visible ink layer 12 is identified even under irradiation with ultraviolet rays.

  Note that the ultraviolet irradiation conditions are the same as those described in the first embodiment. Therefore, the description of the details is omitted.

  In the imaging step, the reflected light reflected by the non-latent image region B and / or the fluorescence generated in the non-latent image region B (hereinafter referred to as “reflected light”) are received and visualized. This is performed by imaging the latent image area A, the non-latent image area B, and the other non-latent image area C that have been visualized in FIG. Here, when the visible ink layer 12 is made of a layer that reflects ultraviolet rays, reflected light reflected by the visible ink layer 12 can also be received. The light receiving conditions are the same as those described in the first embodiment. Therefore, the description of the details is omitted.

  Further, in the latent image printed matter imaging method of the present embodiment, after the imaging process, in addition to the latent image ink layer 11, an inspection process for confirming the presence or absence of printing defects in the visible ink layer 12 can be performed.

  Note that the imaging apparatus used in the method for imaging a latent image printed material according to the present embodiment can employ the same configuration as the imaging apparatus used in the first embodiment. Therefore, the description of the details is omitted.

  Hereinafter, preferred embodiments of the present invention will be described in detail by way of example. However, materials, contents, and the like described in the following examples are not intended to limit the scope of the present invention only to those unless otherwise specified.

(Preparation of aqueous ink composition for latent image)
First, a pigment composition was prepared. That is, titanium oxide nanoparticles as a pigment, sodium polyacrylate as a pigment dispersant, and pure water as a dispersion medium are placed in a container, and dispersed for 24 hours at room temperature (dispersion by a paint shaker, manufactured by Asada Tekko Co., Ltd.). Time) dispersed. In addition, zirconia beads were mixed during dispersion. This produced the pigment composition. As the titanium oxide nanoparticles, TTO-55A (model number, crystal structure; rutile type, average primary particle diameter 40 nm) manufactured by Ishihara Sangyo Co., Ltd. was used. Furthermore, the shape of the titanium oxide nanoparticles was substantially spherical. Further, as sodium polyacrylate, TEGO Dispers 715W (mass average molecular weight 3000) manufactured by Evonik was used.

  Next, polyglycerin fatty acid ester (trade name: SY Glister, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) as a surface tension modifier, propylene glycol and pure water as a wetting agent are added to the pigment composition. It prepared so that it might become the mixing | blending ratio shown, and stirred with the disper. Thus, a latent ink aqueous ink composition was produced.

  In addition, in the preparation process of the pigment composition and the aqueous ink composition for latent images, no bubbles were generated, so the defoaming step by adding an antifoaming agent was not performed. Further, the numerical values in the following Table 1 are expressed in mass% with respect to the total mass of the latent image water-based ink composition unless otherwise specified. Each material complies with the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law.

(Preparation of aqueous ink composition A for visible image)
First, a pigment composition was prepared. That is, carbon black as a pigment, polyoxyethylene alkyl ether as a pigment dispersant, and pure water as a dispersion medium are put in a container, and dispersed for 24 hours at room temperature (dispersion by a paint shaker, manufactured by Asada Tekko Co., Ltd.). Time) dispersed. In addition, zirconia beads were mixed during dispersion. This produced the pigment composition.

  Next, polyglycerin fatty acid ester (trade name: SY Glister, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) as a surface tension modifier, propylene glycol and pure water as a wetting agent are added to the pigment composition. It prepared so that it might become the mixing | blending ratio shown, and stirred with the disper. As a result, a water-based ink composition for visible images was produced.

  The numerical values in Table 2 below are expressed in mass% with respect to the total mass of the visible image water-based ink composition A unless otherwise specified. Each material complies with the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law.

(Preparation of aqueous ink composition B for visible image)
Add edible green 3 as a dye, polyglycerin fatty acid ester (trade name: SY Glyster, Sakamoto Yakuhin Kogyo Co., Ltd.) as a surface tension adjuster, propylene glycol and pure water as a wetting agent, and in Table 3 below It prepared so that it might become the mixing | blending ratio shown, and stirred with the disper. As a result, a water-based ink composition B for visible images was produced.

(Light absorption spectrum of aqueous ink composition for latent image)
About the aqueous ink composition for latent images, the absorption spectrum in the ultraviolet-visible light region (190 nm to 500 nm) was confirmed using a spectrophotometer (trade name: UVmini-1240, manufactured by Shimadzu Corporation). In addition, since the density | concentration was too high to measure the prepared aqueous ink composition for latent images in the state of a stock solution, it measured by what was diluted 4000 times with pure water. For the measurement, a quartz cell having an optical path length of 1 cm was used. The results are shown in FIG.

(Light absorption spectrum of water-based ink compositions A and B for visible images)
About each of the water-based ink compositions A and B for visible images, the absorption spectrum in the ultraviolet-visible light region (260 nm to 800 nm) was measured using a spectrophotometer (trade name: UVmini-1240, manufactured by Shimadzu Corporation). confirmed. In addition, since the density | concentration is too high to measure each prepared aqueous ink composition A and B for visible images in the state of an undiluted | stock solution, it measured by what was diluted 4000 times with pure water. For the measurement, a quartz cell having an optical path length of 1 cm was used. The results are shown in FIG.

(Measurement of mass average molecular weight of sodium polyacrylate)
The mass average molecular weight of sodium alginate is a value determined by gel permeation chromatography (GPC) using polyethylene oxide (PEO) / polyethylene glycol (PEG) as a standard product.

(Measurement of average primary particle size and average dispersed particle size of titanium oxide nanoparticles)
The average primary particle diameter of titanium oxide nanoparticles and the average dispersed particle diameters D50 and D99 were measured by a dynamic light scattering method using Microtrac UPA-EX150 (trade name, manufactured by Nikkiso Co., Ltd.).

(Examples 1-7)
A latent image was printed on an uncoated tablet by an ink jet recording method using the latent image aqueous ink composed of the above-described latent image aqueous ink composition. Printing was performed only on one side of the uncoated tablet, and was performed by a single pass (one pass) method using an inkjet printer (printing jig with a KC 600 dpi head). The printing conditions were a mass per droplet of 7 ng and an appropriate amount of liquid of 7 pl. Further, after printing, the printed image surface was dried by natural drying for 24 hours.

  Next, with respect to the uncoated tablet on which the latent image is printed, the latent image aqueous ink is applied to a region (non-latent image region B) that is not printed with the latent image aqueous ink composition under visible light (room light). The difference in gradation value of the area printed with the composition (latent image area A) was determined. A camera with built-in smartphone (trade name: iPhone6 (registered trademark), manufactured by Apple Inc.) was used to capture the surface of the uncoated tablet on which the latent image was printed.

  The difference in gradation value was determined as follows. That is, image data captured and acquired by a digital camera was converted into an 8-bit gray scale using commercially available software, and 256 gradation values from 0 to 255 in a plurality of pixels were obtained. Further, the average value of the obtained gradation values was calculated, and the difference between the gradation values was calculated by subtracting the average value of the gradation values of the non-latent image area B from the average value of the gradation values of the latent image area A.

Next, the uncoated tablet on which the latent image was printed was irradiated with ultraviolet rays while changing the wavelength for each example (imaging step), and the latent image was visualized to take an image (imaging step). As the irradiation means, a xenon light source (trade name: MAX-303) manufactured by Asahi Spectroscopic Co., Ltd. shown in Table 4 below was used. The wavelength of the ultraviolet rays to be irradiated was changed by using a mirror module attached to the xenon light source and various UV bandpass filters (first optical filters) in combination. As shown in Table 6 below, the ultraviolet wavelength was 260 nm, 280 nm, 300 nm, 320 nm, 340 nm, 360 nm, and 380 nm. The light intensity of the xenon light source was about 5000 μW / cm ² .

  Moreover, as an imaging means used in the imaging process, an ultraviolet camera shown in Table 5 below was used. Imaging was performed in a dark room where outside light other than the xenon light source did not enter.

  Subsequently, a region printed with the latent aqueous ink composition (latent image region A) with respect to a region not printed with the latent image aqueous ink composition (non-latent image region B) under irradiation with ultraviolet light of each wavelength. ) Gradation value difference was calculated. The difference between the gradation values was determined in the same manner as in the case of irradiation with visible light. The results are shown in Table 6 below.

(Examples 8 to 12)
In Examples 8 to 12, the wavelength of ultraviolet rays irradiated in the visualization step was set to 260 nm, and the light intensity of the xenon light source was changed to the values shown in Table 7 below. Otherwise, in the same manner as in Example 1, each latent image was visualized and then imaged with an ultraviolet camera. Further, in the same manner as in Example 1, the difference in gradation value of the latent image region A with respect to the non-latent image region B under the irradiation of ultraviolet rays having a wavelength of 260 nm was calculated. The results are shown in Table 7 below.

(Comparative Examples 1-3)
In Comparative Examples 1 to 3, the wavelength of ultraviolet rays irradiated in the visualization step was set to 260 nm, and the light intensity of the xenon light source was changed to the values shown in Table 7 below. Otherwise, in the same manner as in Example 1, each latent image was visualized and then imaged with an ultraviolet camera. Further, in the same manner as in Example 1, the difference in gradation value of the latent image region A with respect to the non-latent image region B under the irradiation of ultraviolet rays having a wavelength of 260 nm was calculated. The results are shown in Table 7 below.

(Example 13)
A visible image was printed on an uncoated tablet by the inkjet recording method using the above-described aqueous ink for visible image composed of the aqueous ink composition A for visible image. Printing was performed only on one side of the uncoated tablet, and was performed by a single pass (one pass) method using an inkjet printer (printing jig with a KC 600 dpi head). The printing conditions were a mass per droplet of 7 ng and an appropriate amount of liquid of 7 pl. Further, after printing, the printed image surface was dried by natural drying for 24 hours.

  Next, the latent image was printed on the uncoated tablet by the inkjet recording method using the latent ink for a latent image made of the above-described aqueous ink composition for a latent image. The latent image was printed on the printing surface of the visible image. Further, a GS1QR code was printed as a latent image. Furthermore, the printing method and printing conditions were the same as in Example 1.

Next, on the uncoated tablet on which the visible image and the latent image are printed, a region not printed with the visible image aqueous ink composition A and the latent image aqueous ink composition (non-latent) under visible light (room light). A difference in gradation value of an area (latent image area A) printed with the latent ink composition for latent image with respect to the image area B) was determined. Further, the difference in gradation value of the region (the other non-latent image region C) printed with the visible ink aqueous ink composition A with respect to the non-latent image region B was also determined. A digital camera (trade name: PIAS ^™ -II, manufactured by QEA) was used to capture the surface of the uncoated tablet on which the visible image and the latent image were printed.

  The difference in gradation value was determined as follows. That is, for the image data captured and acquired by the digital camera, the tone value in terms of 8-bit gray scale calculated by the intermediate value method was obtained. Further, the gradation value difference was calculated by subtracting the gradation value of the non-latent image area B from the obtained gradation value of the latent image area A.

  Next, ultraviolet light having a wavelength of 320 nm is irradiated to the uncoated tablets on which the visible image and the latent image are printed (visualization step), and the latent image is visualized, and the visible image is converted into a latent image to be captured. Performed (imaging process). The irradiation means, the irradiation conditions excluding the ultraviolet wavelength region, and the imaging device were the same as those in Example 1.

  Subsequently, the aqueous ink composition for a latent image with respect to an area not printed with the aqueous ink composition for a visible image A and the aqueous ink composition for a latent image (non-latent image area B) under irradiation with ultraviolet rays of each wavelength. The difference in gradation value of the area printed in (latent image area A) was calculated. Further, the difference in gradation value of the region (the other non-latent image region C) printed with the visible ink aqueous ink composition A with respect to the non-latent image region B was also determined. The difference between the gradation values was obtained in the same manner as in the case of ultraviolet irradiation in Example 1. The results are shown in Table 8 below. In obtaining the difference in the gradation value of the latent image area A with respect to the non-latent image area B, image processing such as adjustment of brightness, color, contrast, and binarization is performed on the other non-latent image area C. By making it invisible, it may be obtained as a difference in gradation value of the latent image area A with respect to an area other than the latent image area A.

(Example 14)
In Example 14, as compared with Example 13, the visible image water-based ink composition B was used in place of the visible image water-based ink composition A. Otherwise, in the same manner as in Example 13, each latent image was visualized and imaged with an ultraviolet camera. In the same manner as in Example 13, the gradation value of the latent image area A with respect to the non-latent image area B and the other non-latent image area C gradation values with respect to the non-latent image area B under irradiation with ultraviolet rays having a wavelength of 320 nm. Each difference was calculated. The results are shown in Table 8 below.

(Visibility and readability of visualized latent image)
In Examples 1 to 11 and Comparative Examples 1 to 3, the visibility of visualized latent images under ultraviolet irradiation was evaluated. Moreover, the visibility under visible light was also evaluated for the uncoated tablets before ultraviolet irradiation. The evaluation criteria were as follows. The results are shown in Tables 6 and 7.
○: The difference in gradation value of the latent image area A with respect to the non-latent image area B is 5 or more, and the latent image can be visually recognized. ×: The difference in gradation value of the latent image area A with respect to the non-latent image area B is less than 5. It is difficult to see the latent image

In Examples 13 and 14, the visibility of a visible image and a visualized latent image under ultraviolet irradiation was evaluated. Moreover, the visibility of the visible image under visible light was also evaluated for the uncoated tablets before ultraviolet irradiation. In addition to the above, the evaluation criteria were as follows. The results are shown in Table 8.
○: The difference in gradation value of the non-latent image area C from the other non-latent image area C is 5 or more, and a visible image can be visually recognized. X: The gradation of the other non-latent image area C relative to the non-latent image area B The difference in values is less than 5, making it difficult to view visible images

Furthermore, in Examples 13 and 14, the readability of a GS1QR code printed as a latent image (hereinafter referred to as “latent image GS1QR code”) was also evaluated. The evaluation is performed by holding a smartphone built-in camera (trade name: iPhone6 (registered trademark), manufactured by Apple Inc.) over the image captured in the above-described visibility evaluation, and a GS1QR code reading application (application name: GS1QR scodt, Leontec). The latent image GS1QR code was read using The evaluation criteria were as follows. The results are shown in Table 8.
○: The latent image GS1QR code can be read, and the displayed internal information is accurate. Δ: The latent image GS1QR code can be read, but the displayed internal information is inaccurate. X: The latent image GS1QR code Unreadable

(result)
As shown in Table 6, the difference in the gradation value of the latent image area A with respect to the non-latent image area B under visible light irradiation of the uncoated tablet on which the latent image is printed is 1, and the latent image is confirmed visually. I couldn't. Thereby, it was confirmed that a good latent image can be printed by using titanium oxide nanoparticles as a pigment as the aqueous ink composition for a latent image.

  Next, as shown in Table 6, when the uncoated tablets of Examples 1 to 7 were irradiated with ultraviolet rays having a predetermined wavelength in the range of 260 nm to 380 nm, the latent images printed with the aqueous ink composition for latent images were used. In the region A, the irradiated ultraviolet rays were absorbed, and as a result, the black image was picked up by the ultraviolet camera. On the other hand, in the non-latent image area B which is not printed with the latent image aqueous ink composition, the irradiated ultraviolet rays were reflected, and as a result, white images were taken with an ultraviolet camera. Further, in each of the first to seventh embodiments, the difference in the gradation value of the latent image area A with respect to the non-latent image area B can be set to 5 or more. The contrast can be generated to such an extent that it is sufficiently visible. As a result, in printing using the aqueous ink composition for latent images containing titanium oxide nanoparticles in the pigment, it was confirmed that the latent image can be visualized under ultraviolet irradiation, and the printed image can be sufficiently identified. .

In addition, as shown in Table 7, when the uncoated tablets of Examples 8 to 12 were irradiated with ultraviolet rays having a predetermined light intensity in the range of about 5000 μW / cm ^{2 to} 30000 μW / cm ² , the non-latent image region B was irradiated. It was confirmed that the gradation value difference of the latent image area A can be controlled to 5 or more. In particular, in the case where the wavelength region of ultraviolet rays is 260 nm as in Example 10, when the light intensity is about 20000 μW / cm ² , the difference in the gradation value of the latent image region A with respect to the non-latent image region B is maximized. I understood that I can do it.

On the other hand, when the light intensity of ultraviolet rays is about 3000 μW / cm ² as in Comparative Example 1 or when the light intensity is about 40000 μW / cm ² or more as in Comparative Examples 2 and 3, the non-latent image region It was difficult to make the difference in gradation value of the latent image area A with respect to B 5 or more, and the latent image could not be sufficiently visualized with good contrast.

  Moreover, as shown in Table 8, in Examples 13 and 14, the difference in the gradation value of the latent image area A with respect to the non-latent image area B under irradiation of visible light of the uncoated tablet is 3.5 and 1, respectively. The latent image could not be confirmed visually. Further, the latent image GS1QR code could not be read even in the evaluation of the readability of the latent image GS1QR code. Thereby, it was confirmed that a good latent image can be printed by using titanium oxide nanoparticles as a pigment as the aqueous ink composition for a latent image. On the other hand, the difference in the gradation values of the non-latent image area C with respect to the non-latent image area B under the visible light irradiation of the uncoated tablet is 81.5 and 139.5, respectively. We were able to.

  Next, as shown in Table 8, when the uncoated tablets of Examples 13 and 14 were each irradiated with ultraviolet rays having a wavelength of 320 nm, the latent image area A printed with the latent image aqueous ink composition was irradiated. As a result of the absorbed ultraviolet light, it was picked up black by an ultraviolet camera. On the other hand, in the non-latent image area B which is not printed with the latent image aqueous ink composition, the irradiated ultraviolet rays were reflected, and as a result, white images were taken with an ultraviolet camera. However, in Example 13, in the other non-latent image area C printed with the water-based ink composition for visible image using Green No. 3, the visible image was converted into a latent image, and as a result, the ultraviolet camera captured white, The visible image could not be identified. On the other hand, in Example 14, as a result of absorption of the irradiated ultraviolet rays in other non-latent image areas C printed with the visible ink aqueous ink composition using carbon black, the ultraviolet camera captured the image in black. . In the evaluation of the readability of the latent image GS1QR code, the latent image GS1QR code could be read in both Examples 13 and 14. In particular, in Example 14, both the latent image GS1QR code and the visible image were visually recognized, but information contained in the latent image GS1QR code was also correctly displayed. As a result, it was also found that the latent image GS1QR code can be accurately read in both Example 13 and Example 14.

DESCRIPTION OF SYMBOLS 10 Solid preparation 11 Latent image ink layer 12 Visible ink layer 21 Light irradiation means 22 Imaging means 23 1st optical filter 24 2nd optical filter A Latent image area B Non-latent image area C Other non-latent image area

Claims (12)

A latent image printed matter of a solid preparation in which a latent image is provided on at least a part of a surface,
A latent image region in which the latent image is formed by a latent image ink layer that absorbs ultraviolet rays in a wavelength range of 200 nm or more and less than 400 nm;
And at least a non-latent image region that reflects ultraviolet light in the wavelength region and / or emits fluorescence.
The difference in gradation value of the latent image region with respect to the non-latent image region when the latent image region and the non-latent image region are irradiated with visible light is less than 5,
A latent image printed matter of a solid preparation in which a difference in gradation value of a latent image region with respect to a non-latent image region is 5 or more when the latent image region and the non-latent image region are irradiated with light containing at least ultraviolet rays in the wavelength range. The surface further includes another non-latent image region in which a visible image is formed by the visible ink layer that absorbs the visible light,
2. The solid according to claim 1, wherein when the visible light is irradiated to the non-latent image area and the other non-latent image area, a difference in gradation value of the other non-latent image area with respect to the non-latent image area is 5 or more. Latent image printed product. The visible ink layer is a layer that transmits or reflects ultraviolet rays in the wavelength range,
The difference in gradation value between the non-latent image area and the other non-latent image area when the non-latent image area and the other non-latent image area are irradiated with light including ultraviolet rays in the wavelength range is less than 5. 3. A latent image print of the solid preparation according to 2.   The latent image printed matter according to any one of claims 1 to 3, wherein the latent image ink layer contains at least titanium oxide particles as a pigment.   The latent image print of the solid preparation according to any one of claims 1 to 4, wherein the latent image ink layer has a light-transmitting property or a light-reflecting property with respect to visible light. A method for imaging a latent image printed matter of a solid preparation in which a latent image is provided on at least a part of a surface,
The solid preparation is
A latent image ink layer that absorbs ultraviolet rays having a wavelength range of 200 nm or more and less than 400 nm, and a latent image region in which the latent image is formed by the latent image ink layer;
And at least a non-latent image region that reflects ultraviolet light in the wavelength region and / or emits fluorescence.
The difference in gradation value of the latent image region with respect to the non-latent image latent image region when the latent image region and the non-latent image region are irradiated with visible light is less than 5, and the latent image region and the non-latent image region The difference in gradation value of the latent image area with respect to the non-latent image area when irradiated with light containing ultraviolet rays in the wavelength range is 5 or more,
A visualizing step of irradiating the latent image region and the non-latent image region with irradiation light including at least ultraviolet rays in the wavelength region to visualize the latent image in the latent image region;
The latent image region and the non-latent image visualized in the visualization step by receiving the reflected light reflected by the non-latent image region and / or the fluorescence generated in the non-latent image region. An imaging method of a latent image printed matter of a solid preparation, comprising an imaging step of imaging an area.   The imaging method of a latent image printed matter of a solid preparation according to claim 6, wherein the visualization step is a step of using only ultraviolet rays having a wavelength range of 200 nm or more and less than 400 nm as the irradiation light.   The wavelength range of the ultraviolet rays included in the irradiation light in the visualization step and the wavelength range of the reflected light and / or fluorescence received in the imaging step overlap at least partially. A method for imaging a latent image print of the solid preparation described. The solid preparation is
And further has another non-latent image region in which a visible image is formed by the visible ink layer that absorbs visible light,
The difference between the gradation values of the other non-latent image areas with respect to the non-latent image areas when the non-latent image areas and the other non-latent image areas are irradiated with visible light is 5 or more,
The method of imaging a latent image printed matter of any one of claims 6 to 8, wherein the imaging step is a step of imaging the other non-latent image region. The visible ink layer is a layer that transmits or reflects ultraviolet rays in the wavelength range,
The difference in gradation value of the other non-latent image region with respect to the non-latent image region when the non-latent image region and the other non-latent image region are irradiated with light containing ultraviolet rays in the wavelength range is less than 5.
The visualization step is a step of forming a visible image in the other non-latent image region by irradiating the other non-latent image region with irradiation light including at least ultraviolet rays in the wavelength region. ,
The method of imaging a latent image printed matter of a solid preparation according to claim 9, wherein the imaging step is a step of imaging another non-latent image region that has been latentized in the visualization step.   The method for imaging a latent image print of a solid preparation according to any one of claims 6 to 10, wherein the solid preparation contains at least titanium oxide particles as a pigment in the latent image ink layer. The method for capturing a latent image printed matter of a solid preparation according to any one of claims 6 to 11, wherein the latent image ink layer has a light transmissive property or a light reflective property with respect to visible light.