JP2012045762A - Recording medium and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording medium that improves the shieldability of color in a 400-500 nm of wavelength region in infrared absorption images in comparison with when scattered images are not formed on the infrared absorption images.SOLUTION: The recording medium 10 includes: the infrared absorption images 14 that are provided in a base material 12 and includes an organic infrared absorption coloring material excluding a carbon black; and the scattered images 16 that are provided so as to cover the infrared absorption images 14 and include scattering body 16B whose volume mean diameter is 100-400 nm.

Description

  The present invention relates to a recording medium and an image forming apparatus.

  In Patent Document 1, a black ink layer made of black ink made of carbon black and a white ink formed so as to cover the black ink layer on a base material having a light transmittance of 600 nm to 1000 nm of 60% or more. There is described a recording medium comprising an ink layer and having a light transmittance of 20 to 50% at 600 to 1000 nm in a portion where the three layers overlap.

JP 2006-95968 A

  The present invention provides a recording medium having an improved color shielding property in a wavelength region of 400 nm or more and 500 nm or less in an infrared absorption image as compared with a case where a scattering image in the present invention is not formed on the infrared absorption image in the present invention. The issue is to provide.

  The invention according to claim 1 is an infrared absorption image formed by a base material, a first recording material provided on the base material and including an organic infrared absorption color material excluding carbon black, and the infrared absorption. And a scattered image formed by a second recording material that includes a scatterer having a volume average particle diameter of 200 nm or more and 400 nm or less.

The invention according to claim 2 is the recording medium according to claim 1, wherein the base material is white.
The invention according to claim 3 is the recording medium according to claim 1 or 2, wherein the scattered image is white.
The invention according to claim 4 is the recording medium according to any one of claims 1 to 3, wherein the organic infrared absorbing colorant is a perimidine-based squarylium dye represented by the following structural formula (I). It is.

  The invention according to claim 5 is characterized in that the perimidine-based squarylium dye represented by the structural formula (I) has a Bragg angle (2θ ±) in a powder X-ray diffraction spectrum measured by X-ray irradiation with a wavelength of 1.5405 mm on a Cu target. The recording medium according to claim 4, wherein 0.2 °) exhibits diffraction peaks at least at 17.7 °, 19.9 °, 22.1 °, 23.2 °, and 24.9 °.

  According to a sixth aspect of the present invention, there is provided a first recording apparatus for recording an infrared absorption image on a base material using a first recording material containing an organic infrared absorption color material excluding carbon black, and the infrared absorption image. And a second recording device that records a scattered image with a second recording material containing a scatterer having a volume average particle size of 200 nm or more and 400 nm or less so as to cover the image forming apparatus.

  According to the first aspect of the present invention, compared to the case where the scattered image in the present invention is not formed on the infrared absorption image in the present invention, the color shielding property in the wavelength region of 400 nm to 500 nm in the infrared absorption image is present. Be improved.

According to the invention which concerns on Claim 2, the invisibility of an infrared absorption image improves compared with the case where a base material is not white.
According to the invention of claim 3, the invisibility of the infrared absorption image is further improved as compared with the case where the scattered image is not white.

  According to the invention which concerns on Claim 4, the light resistance of an infrared absorption image is improved compared with the case where an organic infrared absorption color material is not the perimidine-type squarylium pigment | dye in this invention.

  According to the invention which concerns on Claim 5, the light resistance of an infrared absorption image is further improved compared with the case where an organic infrared absorption color material is not the perimidine-type squarylium pigment | dye in this invention.

  According to the sixth aspect of the present invention, compared with the case where the scattered image in the present invention is not formed on the infrared absorption image in the present invention, the color shielding property in the wavelength region of 400 nm to 500 nm in the infrared absorption image is present. Be improved.

It is a schematic diagram which shows an example of the recording medium which concerns on this Embodiment. It is a schematic diagram showing an example of a cross section of a region where a laminated image is formed in the recording medium according to the present embodiment. It is a schematic diagram showing an example of a cross section of a region where a laminated image is formed in the recording medium according to the present embodiment. 1 is a schematic diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. 2 is a functional block diagram illustrating an example of a configuration of an image processing apparatus in the image forming apparatus according to the present embodiment. FIG. 4 is a flowchart illustrating processing executed by the image forming apparatus. In an Example, it is a diagram which shows the visible near-infrared absorption spectrum in the tetrahydrofuran solution of the perimidine type | system | group squarylium pigment | dye represented by Structural formula (I) prepared as the infrared absorption coloring material 1. FIG. It is a diagram which shows the particle | grains ((A) particle | grains) of the infrared absorption color material 1, and the X-ray-diffraction spectrum of a raw material which were prepared in the Example. In an Example, it is a diagram which shows the X-ray-diffraction spectrum of (A) particle | grains prepared as particle | grains of the infrared absorption color material 1, and (B) particle | grains prepared as particle | grains of the infrared absorption color material 2. In an Example, it is a diagram which shows the visible near-infrared absorption spectrum of the latex patch of (A) particle | grains, (B) particle | grains, (C) particle | grains, and (D) particle | grains prepared as an infrared absorption color material. In an Example, it is a diagram which shows the light resistance of the latex patch of (A) particle | grains, (B) particle | grains, (C) particle | grains, and (D) particle | grains prepared as an infrared absorption color material, and irradiation time, It is a diagram which shows the relationship with a reflectance. In an Example, it is a diagram which shows the reflectance with respect to the light of the wavelength range of 400 nm or more and 1100 nm or less of each color material prepared as an infrared absorption color material.

  Hereinafter, the present embodiment will be described with reference to the drawings.

(recoding media)
As shown in FIG. 1, in the recording medium 10 of the present embodiment, a laminated image 18 is formed on a base material 12. As shown in FIG. 2, the laminated image 18 has a configuration in which a scattered image 16 is provided on the infrared absorption image 14 provided on the base material 12 so as to cover the infrared absorption image 14. Yes.

  The recording medium 10 in the present embodiment corresponds to the recording medium of the present invention, and the infrared absorption image 14 corresponds to the infrared absorption image in the recording medium of the present invention. The scattered image 16 corresponds to the scattered image in the recording medium of the present invention.

  The substrate 12 may be a member on which the laminated image 18 is formed, and examples thereof include recording paper, plastic plates, OHP sheets (overhead projector films), and the like. Especially, it is desirable to use the white base material 12 from a viewpoint of the improvement of the invisibility of the infrared absorption image 14 which mentions the detail in the lamination | stacking image 18 later.

  The infrared absorption image 14 formed on the substrate 12 is an image having infrared absorptivity, and is formed of a first recording material containing an organic infrared absorption color material excluding carbon black (details will be described later). .

  In the present embodiment, “having infrared absorption” means that an infrared absorption image 14 (covered by the scattered image 16) is formed when an image having a printing coverage of 100% is formed by the first recording material. The reflectance when irradiated with infrared light (light in a wavelength region of 700 nm to 900 nm) is 80% or less at least in any wavelength within the wavelength region of the infrared light. It shows that there is.

  The infrared absorption image 14 is read by irradiating infrared light and receiving the reflected light. Specifically, the infrared absorption image 14 uses a general-purpose light receiving element having high spectral sensitivity to infrared light using a semiconductor laser or a light emitting diode that emits infrared light as a light source for optical reading. Is read out. Examples of the light receiving element include a light receiving element made of silicon (CCD (Charge Coupled Device) or the like).

The infrared absorption image 14 may be an image that can be read by infrared light, and a code pattern obtained by encoding predetermined information into a binary image, letters, numbers, and symbols (triangle mark or star mark). Etc.). Examples of the code pattern include an aggregate of dots, a barcode, a QR code (matrix type two-dimensional barcode), and the like.

  In the present embodiment, the infrared absorption image 14 is described as being formed only in a part of the entire region of the substrate 12 as shown in FIG. What is necessary is just to be formed on the top, and is not restricted to such a form. For example, the infrared absorption image 14 may be formed over the entire region of the substrate 12, and the position, region, and range on the substrate 12 to be formed are not limited.

  Here, the infrared absorption image 14 is preferably an “invisible” image. Note that “invisible” means that it is difficult to visually recognize in visible light, and ideally it is not visually recognized (that is, invisible). Specifically, it is assumed that it is invisible that the color difference ΔE between the infrared absorption image 14 formed on the substrate 12 and the substrate 12 is less than 16.

The content of the organic infrared absorbing color material excluding carbon black contained in the first recording material used for forming the infrared absorbing image 14 and the printing of the infrared absorbing image 14 formed by the first recording material. Depending on the coverage, etc., it may become visible. That is, it is considered that the more the content of the organic infrared absorbing colorant contained in the first recording material is, and the higher the print coverage of the infrared absorbing image 14 is, the more likely it is to be visible. It is done.
“Visible” indicates that a color or shape is recognized by visual observation in visible light. Specifically, the visible image indicates that the color difference ΔE between the infrared absorption image 14 formed on the substrate 12 and the substrate 12 is 16 or more.

  In particular, when an organic infrared absorbing color material excluding carbon black is used as the color material contained in the first recording material, the content of the color material contained in the first recording material and the first recording material Depending on the print coverage of the image to be formed, when a white substrate 12 is used as the substrate 12, colors in a wavelength region having a wavelength of 400 nm or more and 500 nm or less may be visually recognized.

  Therefore, in the recording medium 10 of the present embodiment, the scattered image 16 is formed so as to cover the infrared absorption image 14 formed on the substrate 12. As shown in FIG. 3, the scattered image 16 is an image formed by a second recording material including a scatterer 16A having a volume average particle diameter of 200 nm or more and 400 nm or less.

In the recording medium 10 of the present embodiment, the infrared absorption image 14, since it is covered by this scattering image 16, (in FIG. 3, see arrow _{L 1)} light of a wavelength region 500nm or more wavelength 400nm is The scattered image 16 is considered to be scattered by the scatterer 16A. That is, since the volume average particle diameter of the scatterer 16A is 200 nm or more, it is considered that light in the wavelength region of wavelength 400 nm or more and 500 nm or less is scattered. For this reason, it is considered that the scattered image 16 blocks the color in the wavelength region of the wavelength of 400 nm or more and 500 nm or less in the infrared absorption image 14 provided on the substrate 12 side from the scattered image 16.
The volume average particle diameter of the scattering body 16A contained in the scattering image 16, since it is 400nm or less, (in FIG. 3, see arrow L ₂₎ infrared light is transmitted to the infrared absorption scattered images 16 Since the image 14 is reached, it is considered that a decrease in reading accuracy of the infrared absorption image 14 due to infrared light is also suppressed.
Further, if the white base material 12 is used as the base material 12, it is considered that the invisibility of the infrared absorption image 14 is improved by the scattered image 16.
Furthermore, if the scattered image 16 is white, it is considered that the invisibility of the infrared absorption image 14 is further improved. “The scattered image 16 is white” indicates that the minimum reflectance with respect to light having a wavelength in the visible region in the scattered image 16 is 90% or more.

  In addition, while improving the shielding of the color in the wavelength region of 400 nm or more and 500 nm or less in the infrared absorption image 14 by the scattered image 16 as compared with the case where the configuration in the present embodiment is not used, the infrared absorption image 14 to prevent the reading accuracy from being degraded by infrared light, the volume average particle diameter of the scatterer 16A is adjusted within the above range, the concentration of the scatterer 16A in the scattered image 16, the type of the scatterer 16A, It can be realized by adjusting the image coverage (printing rate) or the like by the scattered image 16 or by combining them.

  The volume average particle diameter of the scatterer 16A included in the scattered image 16 is essential to be 200 nm or more and 400 nm or less as described above, but has sufficient scattering ability for light in the wavelength region of wavelength 400 nm or more and 500 nm or less. From the viewpoint, a range of 200 nm to 300 nm is desirable, and a range of 210 nm to 265 nm is more desirable.

  The volume average particle diameter of the scatterer 16A is measured using a laser diffraction particle size distribution measuring device (LA-700: manufactured by Horiba, Ltd.). As a measurement method, a sample in a dispersion is adjusted to have a solid content of about 2 g, and ion exchange water is added thereto to make about 40 ml. This is put into the cell until an appropriate concentration is reached, waits for about 2 minutes, and is measured when the concentration in the cell becomes almost stable. The obtained volume average particle diameter for each channel is accumulated from the smaller volume average particle diameter, and the volume average particle diameter (volume average particle diameter D50) is determined to be 50%.

  Examples of the scatterer 16A include inorganic pigments such as titanium oxide, zinc white, lead white, and zinc sulfide, polymethyl methacrylate-based crosslinked products, and alkylene bismelamine derivatives NN′-bis (4,6diamino-1, Organic white pigments that are fine particles such as 3,5-triazin-2-yl) ethylenediamine, bubbles, and the like.

  Among these, it is desirable to use titanium oxide as the scatterer 16A because of its high refractive index and high scattering ability even with a small amount.

  In order to adjust the volume average particle diameter of the scatterer 16A to the above range, when an inorganic pigment is used as the scatterer 16A, it may be adjusted by changing the pulverization processing conditions such as a bead mill or an attritor. Good. In addition, when an organic white pigment is used as the scatterer 16A, the volume average particle diameter is adjusted to the above range by taking a general fine particle granulating means such as emulsion polymerization and changing the reaction conditions. Adjust it. Further, when bubbles are used as the scatterer 16A, the volume average particle diameter may be adjusted to the above range by changing the amount of the reagent that causes foaming in the medium.

  The content of the scatterer 16A included in the scattered image 16 may be a content that is visually confirmed to be white, and may vary depending on the type of the scatterer 16A and the volume average particle diameter. 5 mass% or more and 40 mass% or less are desirable with respect to the total mass (100 mass%) of the material, and 20 mass% or more and 35 mass% or less are still more desirable.

  Examples of other materials included in the second recording material include an ultraviolet absorber. The total content of these ultraviolet absorbers may be in a range that does not impair the light scattering effect in the above-described wavelength region of 400 nm to 500 nm of the infrared absorption image formed by the second recording material. Specifically, 5 mass% or more and 40 mass% or less are mentioned with respect to the total mass (100 mass%) of a 2nd recording material.

  The second recording material may be configured as a toner used in an electrophotographic image forming apparatus or may be configured as an ink (droplet) of an ink jet printer.

  When the second recording material is a toner used in an electrophotographic image forming apparatus, the second recording material according to the present embodiment can be used alone as a one-component developer or combined with a carrier. Alternatively, it may be used as a two-component developer. A known carrier is used as the carrier, and examples thereof include a resin-coated carrier having a resin coating layer on a core material. Conductive powder or the like may be dispersed in the resin coating layer.

  Further, when the second recording material is a toner used in an electrophotographic image forming apparatus, the second recording material contains a binder resin. Binder resins used include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene, and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate, and acrylic acid. Α-methylene aliphatic monocarboxylic acid esters such as methyl, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, Examples include vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl butyl ether, and homopolymers or copolymers of vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropenyl ketone. Typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include coalescence, polyethylene, and polypropylene. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like are also used as the binder resin.

  Further, when the second recording material is a toner used in an electrophotographic image forming apparatus, the second recording material may further contain a charge control agent, an offset preventing agent, and the like. As the charge control agent, there are a positive charge agent and a negative charge agent. For the positive charge, there are quaternary ammonium compounds. For negative charging, alkylsalicylic acid metal complexes, resin-type charge control agents containing polar groups, and the like can be used. Examples of the offset preventive agent include low molecular weight polyethylene and low molecular weight polypropylene.

  In addition, when the second recording material is a toner used in an electrophotographic image forming apparatus, inorganic particles are used to improve fluidity, powder storage stability, frictional charging control, transfer performance, and cleaning performance. Alternatively, organic particles may be added to the toner surface as an external additive. Examples of the inorganic particles include known particles such as silica, alumina, titania, calcium carbonate, magnesium carbonate, calcium phosphate, cerium oxide and the like. Moreover, you may give a well-known surface treatment to an inorganic particle according to the objective. Examples of the organic particles include an emulsion polymer having a constituent component such as vinylidene fluoride, methyl methacrylate, styrene-methyl methacrylate, or a soap-free polymer.

  On the other hand, when the second recording material is an ink used in an ink jet printer, examples of the second recording material include a water-based ink containing water. In addition, the second recording material of the present embodiment may further contain a water-soluble organic solvent in order to prevent the ink from drying and improve the permeability. Examples of water include ion exchange water, ultrafiltration water, and pure water. Examples of the organic solvent include polyhydric alcohols such as ethylene glycol, diethylene glycol, polyethylene glycol, and glycerin, esters such as N-alkylpyrrolidones, ethyl acetate, and amyl acetate, and lower alcohols such as methanol, ethanol, propanol, and butanol. And glycol ethers such as methanol, butanol, phenol ethylene oxide or propylene oxide adducts. The organic solvent used may be one type or two or more types. As content rate of the organic solvent in the ink used with an inkjet printer, 1 mass% or more and 60 mass% or less are mentioned.

  In addition, when the second recording material according to the present embodiment is an ink used in an ink jet printer, the second recording material includes an ink component in order to satisfy various conditions required for the ink jet printer system. Conventionally known additives are contained. Examples of the additive include a pH adjuster, a specific resistance adjuster, an antioxidant, an antiseptic, an antifungal agent, and a metal sequestering agent. Examples of the pH adjuster include alcohol amines, ammonium salts, metal hydroxides and the like. Examples of the specific resistance adjusting agent include organic salts and inorganic salts. Examples of the metal sequestering agent include chelating agents.

  When the second recording material according to the present embodiment is an ink used in an ink jet printer, polyvinyl alcohol, polyvinyl pyrrolidone, carboxymethyl cellulose, A water-soluble resin such as styrene-acrylic acid resin or styrene-maleic acid resin may be contained.

  Further, when the second recording material according to the present embodiment is an ink for letterpress printing, offset printing, flexographic printing, gravure printing, or silk printing, the second recording material is an oily material containing a polymer or an organic solvent. What is necessary is just to make it the aspect of an ink. Polymers generally include natural resins such as proteins, rubbers, celluloses, shellac, copal, starch, rosin; vinyl resins, acrylic resins, styrene resins, polyolefin resins, novolac phenol resins, etc. Thermoplastic resin; thermosetting resin such as resol type phenol resin urea resin, melamine resin, polyurethane resin, epoxy, unsaturated polyester, and the like. Moreover, as an organic solvent, the organic solvent illustrated in description of the said ink for inkjet printers is mentioned.

  In addition, when the second recording material according to the present embodiment is ink for letterpress printing, offset printing, flexographic printing, gravure printing, or silk printing, the second recording material has flexibility and strength of the printed film. You may further contain additives, such as a plasticizer for improving, a viscosity adjustment, a solvent for drying property improvement, a drying agent, a viscosity modifier, a dispersing agent, various reactants.

  In other words, the scattered image 16 may be an image formed by toner composed of the second recording material, or may be an image formed by droplets composed of the second recording material. . In the case where the scattered image 16 is formed with the toner composed of the second recording material, the image forming apparatus that forms the scattered image 16 is, for example, an electrophotographic image forming image formation using toner. Examples include a forming apparatus. On the other hand, in the case where the scattered image 16 is formed by droplets composed of the second recording material, an image forming apparatus that forms the scattered image 16 is an inkjet type that forms an image by ejecting droplets. An image forming apparatus is mentioned.

On the other hand, the first recording material for forming the infrared absorption image 14 may be configured to include an organic infrared absorption color material excluding carbon black as a color material.
The organic infrared absorbing color material may be any organic infrared absorbing color material having infrared absorptivity and excluding carbon black. For example, naphthalocyanine or the following structural formula (1) is used. Perimidine-based squarylium dyes.

  Among these, the scattered image 16 blocks the color in the region of the wavelength 400 nm to 500 nm in the infrared absorption image 14, and the infrared absorption image 14 is formed from the viewpoint of realizing a thin film of the scattered image 16. As the organic infrared absorbing color material contained in the first recording material, it is desirable to use a perimidine-based squarylium dye represented by the following structural formula (I).

  The perimidine-based squarylium dye represented by the structural formula (I) has higher light resistance than other dyes used for invisible images. This is because the perimidine-based squarylium dye represented by the structural formula (I) has higher crystallinity and lower solubility in the binder resin than other dyes used for invisible images. For this reason, it is thought that the breakage | bonding of the coupling | bonding in a molecule | numerator by absorbing light energy by irradiation of light is suppressed.

As described above, the perimidine-based squarylium dye represented by the structural formula (I) has higher crystallinity than the dye used for infrared absorption images conventionally used. Bragg angles (2θ ± 0.2 °) in the powder X-ray diffraction spectrum measured by X-ray irradiation at a wavelength of 1.5405 mm are at least 9.9 °, 13.2 °, 19.9 °, 20.8 °, those showing diffraction peaks at 23.0 °, those showing diffraction peaks at least 17.7 °, 19.9 °, 22.1 °, 23.2 °, 24.9 °, 8.9, 17 1, 18.4, 22.6, 24.2 and the like showing diffraction peaks.
Among them, those having diffraction peaks at 17.7 °, 19.9 °, 22.1 °, 23.2 °, and 24.9 ° are preferable from the viewpoint of light resistance.

  The perimidine-based squarylium dye represented by the structural formula (I) has a sufficiently low light absorption ability in the visible light wavelength region of 400 nm or more and 750 nm or less and absorbs light in the near infrared light wavelength region of 750 nm or more and 1000 nm or less. The ability is high enough.

This “absorbing ability is sufficiently low” means that the solution has a molar extinction coefficient of at least 8100 M ⁻¹ cm ⁻¹ in the visible light wavelength region of 400 nm to 450 nm and a solution in the visible light wavelength region of 450 nm to 650 nm. the molar absorption coefficient is at least ^{3400 m} -1 ^{cm -1} or less, the molar extinction coefficient of the solution in the visible light wavelength region from 690nm or 650nm is at least ^8800M -1 ^{cm -1} or less, a visible light up to 750nm or 690nm It shows that the molar extinction coefficient of the solution in the wavelength region is at least 37000 M ⁻¹ cm ⁻¹ or less.

Moreover, “absorbing ability is sufficiently high” means that the maximum value of the molar extinction coefficient of the solution in the entire near-infrared wavelength region of 750 nm to 1000 nm is at least 1.5 × 10 ⁵ M ⁻¹ cm ^−1. It is shown above.

  Therefore, the infrared absorption image 14 formed by the first recording material containing the perimidine-based squarylium dye represented by the structural formula (I) has invisibility by visible light and readability by infrared light. It is thought that they are compatible.

  The first recording material for forming the infrared absorption image 14 according to the present embodiment preferably satisfies the conditions represented by the following formulas (II) and (III).

0 ≦ ΔE ≦ 16 Formula (II)
(100-R) ≧ 75 Formula (III)

  In the above formula (II), ΔE represents a color difference in the CIE 1976 L * a * b * color system represented by the following formula (IV). In formula (III), R (unit:%) represents an infrared absorption image 14 Shows the infrared reflectance at a wavelength of 850 nm.

  By satisfying the conditions represented by the above formulas (II) and (III), the invisibility of the infrared absorption image 14 and the ease of taking it by infrared light are compatible, regardless of the color of the first recording material. it is conceivable that. In addition, the long-term reliability of the infrared absorption image 14 is expected due to the high light resistance.

In the above formula (IV), L ₁ , a ₁ , and b ₁ represent the L value, a value, and b value of the surface of the substrate 12 on which various images are not formed, and L ₂ , a ₂ , b ₂ represents an L value, a value, and a value in the infrared absorption image when an infrared absorption image 14 having an adhesion amount of 4 g / m ² is formed on the substrate 12 using the first recording material, respectively. b value is shown.

In the above formula (IV), L ₁ , a ₁ , b ₁ , L ₂ , a ₂ , and b ₂ are obtained using a reflection spectral densitometer. In the present embodiment, L ₁ , a ₁ , b ₁ , L ₂ , a ₂ , and b ₂ are values measured using x-rite 939 manufactured by X-Rite Co., Ltd. as a reflection spectral densitometer.

  The perimidine-based squarylium dye represented by the structural formula (I) can be obtained, for example, according to the following reaction scheme.

  More specifically, by reacting 1,8-diaminonaphthalene and 3,5-dimethylcyclohexanone in a solvent under the condition of azeotropic reflux in the presence of a catalyst, the perimidine intermediate (a) is obtained. Is obtained (step (A-1)).

  Examples of the catalyst used in the step (A-1) include p-toluenesulfonic acid monohydrate, benzenesulfonic acid monohydrate, 4-chlorobenzenesulfonic acid hydrate, pyridine-3-sulfonic acid, and ethanesulfone. Examples include acid, sulfuric acid, nitric acid, and acetic acid. Moreover, alcohol, an aromatic hydrocarbon, etc. are mentioned as a solvent used for the said (A-1) process. The perimidine intermediate (a) is purified by high-speed column chromatography or recrystallization.

  Next, perimidine intermediate (a) and 3,4-dihydroxycyclobut-3-ene-1,2-dione (also referred to as “squaric acid” or “square acid”) are azeotroped in a solvent. By reacting under reflux conditions, a perimidine-based squarylium dye represented by the structural formula (I) is obtained (step (A-2)). The step (A-2) is desirably performed in a nitrogen gas atmosphere.

  As the solvent used in the step (A-2), alcohols such as 1-propanol, 1-butanol and 1-pentanol, aromatic hydrocarbons such as benzene, toluene, xylene and monochlorobenzene, tetrahydrofuran, Ethers such as dioxane, halogenated hydrocarbons such as chloroform, dichloroethane, trichloroethane and dichloropropane, and amides such as N, N-dimethylformamide and N, N-dimethylacetamide are used. In addition, alcohols may be used alone, but solvents such as aromatic hydrocarbons, ethers, halogenated hydrocarbons or amides are desirably used in a mixture with alcohol solvents. Specific examples of the solvent include 1-propanol, 2-propanol, 1-butanol, 2-butanol, a mixed solvent of 1-propanol and benzene, and a mixed solvent of 1-propanol and toluene. , 1-propanol and N, N-dimethylformamide mixed solvent, 2-propanol and benzene mixed solvent, 2-propanol and toluene mixed solvent, 2-propanol and N, N-dimethyl A mixed solvent of formamide, a mixed solvent of 1-butanol and benzene, a mixed solvent of 1-butanol and toluene, a mixed solvent of 1-butanol and N, N-dimethylformamide, a mixed solvent of 2-butanol and benzene, 2- Examples thereof include a mixed solvent of butanol and toluene, and a mixed solvent of 2-butanol and N, N-dimethylformamide. When a mixed solvent is used, the concentration of the alcohol solvent is preferably 1% by volume or more, or 5% by volume or more and 75% by volume or less.

  In the step (A-2), the molar ratio of perimidine derivative (a) to 3,4-dihydroxycyclobut-3-ene-1,2-dione (number of moles of perimidine derivative (a) / 3, 4 -The number of moles of dihydroxycyclobut-3-ene-1,2-dione) is 1 or more and 4 or less, or 1.5 or more and 3 or less. When the molar ratio is less than 1, the yield of the perimidine-based squarylium dye represented by the structural formula (I) may be reduced. When the molar ratio exceeds 4, the utilization efficiency of the perimidine derivative (a) is poor. Accordingly, it may be difficult to separate and purify the perimidine-based squarylium dye represented by the structural formula (I).

  Furthermore, in the step (A-2), when a dehydrating agent is used, the reaction time is shortened, and the yield of the perimidine-based squarylium dye represented by the structural formula (I) tends to be improved. The dehydrating agent is not particularly limited as long as it does not react with the perimidine intermediate (a) and 3,4-dihydroxycyclobut-3-ene-1,2-dione, but trimethyl orthoformate, triethyl orthoformate, ortho Examples include orthoformate esters such as tripropyl formate and tributyl orthoformate, and molecular sieves.

  The reaction temperature in the step (A-2) varies depending on the type of solvent used, but the temperature of the reaction solution is 60 ° C. or higher, or 75 ° C. or higher. For example, when a mixed solvent of 1-butanol and toluene is used, the temperature of the reaction solution is preferably 75 ° C. or higher and 105 ° C.

  The reaction time in the step (A-2) varies depending on the type of solvent or the temperature of the reaction solution. For example, the reaction solution temperature is set to 90 ° C. or more and 105 ° C. or less using a mixed solvent of 1-butanol and toluene. When making it react, reaction time is 2 hours or more and 4 hours or less.

  The perimidine-based squarylium dye represented by the structural formula (I) produced in the step (A-2) is purified by solvent washing, high-speed column chromatography or recrystallization.

In the recording medium 10 of the present embodiment, the perimidine-based squarylium dye represented by the structural formula (I) contained in the first recording material for recording the infrared absorption image 14 may be subjected to a pigmentation treatment. Although it is good, it is considered that the crystal system is likely to change when the pigmentation treatment is performed.
Therefore, it is desirable to adjust the pigmentation treatment method and treatment conditions so that the conversion of the crystal system of the perimidine-based squarylium pigment particles (raw material) before the pigmentation treatment is suppressed. That is, it is desirable to adjust so as to show an X-ray diffraction peak of perimidine-based squarylium pigment particles. Specifically, in the perimidine-based squarylium dye, the Bragg angle (2θ ± 0.2 °) in a powder X-ray diffraction spectrum measured by X-ray irradiation with a wavelength of 1.5405 mm with a Cu target is at least 17.7 °, Since it is preferable to have a diffraction peak at 19.9 °, 22.1 °, 23.2 °, and 24.9 °, the perimidine-based squarylium dye after the pigmentation treatment is adjusted to show the diffraction peak. It is desirable from the viewpoint of improving light resistance.

  Examples of the pigmentation method include a method in which a perimidine-based squarylium dye represented by the structural formula (I) is mixed with a sodium dodecylbenzenesulfonate aqueous solution, and the mixture is subjected to a pigmentation treatment. You may adjust a density | concentration by adding water to a liquid mixture as needed. Moreover, a bead mill processing apparatus is mentioned as an apparatus used for a pigmentation process.

  In the present embodiment, the first recording material constituting the infrared absorption image 14 preferably contains a perimidine-based squarylium dye represented by the structural formula (I) as particles. The perimidine-based squarylium dye represented by the structural formula (I) has a larger intermolecular interaction and higher crystallinity than those conventionally used for invisible images. For this reason, by incorporating the perimidine-based squarylium dye represented by the structural formula (I) in the form of particles into the first recording material, infrared coloring is achieved as compared with dyes used for invisible images that have been conventionally used. It is thought that capacity and light resistance are further improved.

  The particles of perimidine-based squarylium dye represented by the above structural formula (I) are prepared by, for example, dissolving the purified product after the step (A-2) in tetrahydrofuran, and using the syringe for cooling the solution with ice-cooled distilled water. The mixture is poured into the mixture with stirring to form a precipitate. The precipitate is collected by suction filtration, washed with distilled water, and then vacuum dried. At this time, by adjusting the concentration of the perimidine-based squarylium dye represented by the structural formula (I) in the solution, the injection rate of the solution, the amount or temperature of distilled water, the stirring rate, and the like, the resulting precipitate particles The diameter is adjusted.

Examples of the median diameter d50 of the perimidine-based squarylium dye particles represented by the structural formula (I) include 10 nm to 300 nm, and 20 nm to 200 nm.
When the median diameter d50 of the particles of the perimidine-based squarylium dye represented by the structural formula (I) is within the above range, it is considered that the decrease in light resistance is suppressed and the infrared coloring ability is improved.

  The treatment for controlling the particle formation and the median diameter may be performed either before or after the pigmentation treatment.

  In the present embodiment, if the first recording material constituting the infrared absorption image 14 is “invisible” if the first recording material and the invisible infrared absorption image 14 formed by the first recording material are “invisible”. The perimidine-based squarylium dye represented by the structural formula (I) contained in the first recording material may further contain components other than the perimidine-based squarylium dye represented by the structural formula (I). Is, for example, not less than 0.05% by mass and not more than 3% by mass, or not less than 0.1% by mass and not more than 2% by mass with respect to the total mass (100% by mass) of the first recording material.

  When the first recording material is a toner used in an electrophotographic image forming apparatus, the recording material according to the present embodiment can be used alone as a one-component developer or combined with a carrier. It may be used as a component developer. A known carrier is used as the carrier, and examples thereof include a resin-coated carrier having a resin coating layer on a core material. Conductive powder or the like may be dispersed in the resin coating layer.

  Further, when the first recording material is a toner used in an electrophotographic image forming apparatus, the recording material contains a binder resin. Binder resins used include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene, and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate, and acrylic acid. Α-methylene aliphatic monocarboxylic acid esters such as methyl, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, Examples include vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl butyl ether, and homopolymers or copolymers of vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropenyl ketone. Typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include coalescence, polyethylene, and polypropylene. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like are also used as the binder resin.

  Further, when the first recording material is a toner used in an electrophotographic image forming apparatus, the recording material may further contain a charge control agent, an offset preventing agent, and the like. As the charge control agent, there are a positive charge agent and a negative charge agent. For the positive charge, there are quaternary ammonium compounds. For negative charging, alkylsalicylic acid metal complexes, resin-type charge control agents containing polar groups, and the like can be used. Examples of the offset preventive agent include low molecular weight polyethylene and low molecular weight polypropylene.

  In addition, when the first recording material is a toner used in an electrophotographic image forming apparatus, inorganic particles are used to improve fluidity, powder storage stability, frictional charging control, transfer performance, and cleaning performance. Alternatively, organic particles may be added to the toner surface as an external additive. Examples of the inorganic particles include known particles such as silica, alumina, titania, calcium carbonate, magnesium carbonate, calcium phosphate, cerium oxide and the like. Moreover, you may give a well-known surface treatment to an inorganic particle according to the objective. Examples of the organic particles include an emulsion polymer having a constituent component such as vinylidene fluoride, methyl methacrylate, styrene-methyl methacrylate, or a soap-free polymer.

  On the other hand, when the first recording material is an ink used in an ink jet printer, examples of the recording material include a water-based ink containing water. Further, the recording material of the present embodiment may further contain a water-soluble organic solvent in order to prevent the ink from drying and to improve the permeability. Examples of water include ion exchange water, ultrafiltration water, and pure water. Examples of the organic solvent include polyhydric alcohols such as ethylene glycol, diethylene glycol, polyethylene glycol, and glycerin, esters such as N-alkylpyrrolidones, ethyl acetate, and amyl acetate, and lower alcohols such as methanol, ethanol, propanol, and butanol. And glycol ethers such as methanol, butanol, phenol ethylene oxide or propylene oxide adducts. The organic solvent used may be one type or two or more types. The organic solvent is appropriately selected in consideration of hygroscopicity, moisture retention, solubility of the perimidine-based squarylium pigment according to the present embodiment, permeability, ink viscosity, freezing point, and the like. As content rate of the organic solvent in the ink used with an inkjet printer, 1 mass% or more and 60 mass% or less are mentioned.

  In addition, when the first recording material according to the present embodiment is an ink used in an ink jet printer, the recording material is conventionally known as an ink component in order to satisfy various conditions required for the ink jet printer system. The additive is contained. Examples of the additive include a pH adjuster, a specific resistance adjuster, an antioxidant, an antiseptic, an antifungal agent, and a metal sequestering agent. Examples of the pH adjuster include alcohol amines, ammonium salts, metal hydroxides and the like. Examples of the specific resistance adjusting agent include organic salts and inorganic salts. Examples of the metal sequestering agent include chelating agents.

  When the first recording material according to the present embodiment is an ink used in an ink jet printer, polyvinyl alcohol, polyvinyl pyrrolidone, carboxymethyl cellulose, A water-soluble resin such as styrene-acrylic acid resin or styrene-maleic acid resin may be contained.

  When the first recording material according to the present embodiment is an ink for letterpress printing, offset printing, flexographic printing, gravure printing, or silk printing, the recording material is an oil-based ink containing a polymer or an organic solvent. What is necessary is just to be an aspect. Polymers generally include natural resins such as proteins, rubbers, celluloses, shellac, copal, starch, rosin; vinyl resins, acrylic resins, styrene resins, polyolefin resins, novolac phenol resins, etc. Thermoplastic resin; thermosetting resin such as resol type phenol resin urea resin, melamine resin, polyurethane resin, epoxy, unsaturated polyester, and the like. Moreover, as an organic solvent, the organic solvent illustrated in description of the said ink for inkjet printers is mentioned.

  In addition, when the first recording material according to the present embodiment is ink for letterpress printing, offset printing, flexographic printing, gravure printing, or silk printing, the first recording material has flexibility and strength of the printed film. You may further contain additives, such as a plasticizer for improving, a viscosity adjustment, a solvent for drying property improvement, a drying agent, a viscosity modifier, a dispersing agent, various reactants.

  Since the perimidine-based squarylium dye represented by the structural formula (I) is a dye having excellent light resistance as described above, the first recording material containing the dye has excellent light resistance. From the viewpoint of further improving the light resistance of the first recording material, it may be configured to further contain a stabilizer. As the stabilizer, it is necessary to receive energy from the excited organic near-infrared absorbing dye, and a stabilizer having an absorption band on the longer wavelength side than the absorption band of the near-infrared absorbing dye is used. As the stabilizer, it is preferable to use a stabilizer that is hardly decomposed by singlet oxygen and highly compatible with the perimidine-based squarylium dye represented by the structural formula (I). An example of the stabilizer having this property is an organometallic complex compound. Especially, the compound represented with the following general formula (V) is mentioned.

In general formula (V), R ¹ , R ² , R ³ and R ⁴ may be the same or different from each other, and each represents a substituted or unsubstituted phenyl group. When the phenyl group represented by R ¹ , R ² , R ³ , R ⁴ has a substituent, examples of the substituent include H, NH ₂ , OH, N (C _h H _{2h + 1} ) ₂ , OC _h H _{2h + 1} , C _h H _2h-1 , C _h H _{2h + 1} , C _h H _2h OH, or C _h H _2h OC _i H _{2i + 1} (h represents an integer from 1 to 18, i represents an integer from 1 to 6), etc. It is done. X ¹ , X ² , X ³ , and X ⁴ may be the same or different from each other, and each represents O, S, or Se, and Y represents a transition such as Ni, Co, Mn, Pd, Cu, or Pt. Indicates metal.

  Among the compounds represented by the general formula (V), a compound represented by the following structural formula (VI) is particularly desirable.

  The concentration of the stabilizer contained in the first recording material is 1/10 to 2 times the mass of the perimidine-based squarylium dye represented by the structural formula (I).

  The infrared absorption image 14 may be an image formed by toner composed of the first recording material, or may be an image formed by droplets composed of the first recording material. . In the case of forming the infrared absorption image 14 with the toner composed of the first recording material, the image forming apparatus for forming the infrared absorption image 14 may be, for example, an electronic device that forms an image using toner. A photographic image forming apparatus may be mentioned. On the other hand, in the case where the infrared absorption image 14 is formed by droplets composed of the first recording material, the image forming apparatus that forms the infrared absorption image 14 forms an image by discharging the droplets. And an inkjet image forming apparatus.

(Image forming device)
Hereinafter, as an example of an apparatus for forming the laminated image 18 of the infrared absorption image 14 and the scattered image 16 on the substrate 12, an embodiment using an electrophotographic image forming apparatus that forms an image with toner is given as an example. I will explain.

  As shown in FIG. 4, the image forming apparatus 11 of the present embodiment includes a laminated image recording unit 15, a visible image recording unit 14A, an intermediate transfer member 17 rotated in the direction of arrow A in the figure, a paper feeding device 27, A paper transport path 31, a fixing device 19, an image processing device 20, an image formation control device 21, a paper discharge device 22, and an input / output device 23 are provided. The laminated image recording unit 15 includes an infrared absorption image recording unit 15A that forms the infrared absorption image 14 and a scattered image recording unit 15B that forms the scattered image 16.

  The image forming apparatus 11 corresponds to the image forming apparatus of the present invention, the infrared absorption image recording unit 15A corresponds to the first recording apparatus of the image forming apparatus of the present invention, and the scattered image recording unit 15B This corresponds to the second recording apparatus of the image forming apparatus of the present invention.

  The outline of the image forming apparatus 11 will be described. The image processing apparatus 20 performs image processing on image data input from the outside such as a personal computer via a network line, a wireless line or the like, and sends it to the image forming control apparatus 21. Output.

  Based on the image data subjected to image processing (first print data, second print data, and third print data, which will be described later), the image formation control device 21 performs the scattered image recording unit 15B, infrared The absorption image recording unit 15A and the visible image recording unit 14A are controlled. Note that the image formation control device 21 may be included in the image processing device 20 as a part of the image processing device 20.

  An input / output device 23 such as a touch panel is provided on the outer surface of the image forming apparatus 11. The input / output device 23 displays control information, instruction information, and the like of the image forming apparatus 11 and accepts input by the user such as instruction information. That is, the user operates the image forming apparatus 11 via the input / output device 23. Note that the input / output device 23 may accept only an input from a switch or the like, may perform only an output such as a display, or may be a combination of these.

Inside the image forming apparatus 11, a laminated image recording unit 15 that records a laminated image and a visible image recording unit 14A that records a visible image are provided. As described above, the laminated image recording unit 15 includes the infrared absorption image recording unit 15A and the scattered image recording unit 15B.
The infrared absorption image recording unit 15A records the infrared absorption image 14 (see FIG. 2) using the toner composed of the first recording material. On the other hand, when the laminated image 18 is formed on the substrate 12, the scattered image recording unit 15B is in a state in which the scattered image 16 is provided so as to cover the infrared absorption image 14 on the substrate 12. The scattered image 16 is recorded.

The visible image recording unit 14A includes a plurality of visible image recording units corresponding to colors constituting the color image. In the present embodiment, the visible image recording unit 14A corresponds to each color of black (K), yellow (Y), magenta (M), and cyan (C), the visible image recording unit 14K, the visible image recording unit 14Y, The visible image recording unit 14M and the visible image recording unit 14C are included.
These scattered image recording unit 15B, infrared absorption image recording unit 15A, visible image recording unit 14K, visible image recording unit 14Y, visible image recording unit 14M, and visible image recording unit 14C are spaced along the intermediate transfer body 17. Are arranged with a space between them.

In the present embodiment, the laminated image recording unit 15 is described as being provided on the upstream side in the transport direction of the intermediate transfer body 17 from the visible image recording unit 14A. It may be provided downstream of the recording unit 14A.
In the present embodiment, the visible image recording unit 14K, the visible image recording unit 14Y, the visible image recording unit 14M, and the visible image recording unit 14C included in the visible image recording unit 14A are upstream in the transport direction of the intermediate transfer body 17. Although the case where it is provided in this order from the side toward the downstream side will be described, such arrangement is not limited.
Note that the arrangement of the scattered image recording unit 15B and the infrared absorption image recording unit 15A in the laminated image recording unit 15 is such that the infrared image formed on the substrate 12 when the laminated image 18 is formed on the substrate 12. It is necessary to have an arrangement in which the scattered image 16 is formed so as to cover the absorption image 14 (that is, to cover the infrared absorption image 14 on the opposite side of the base material 12 with respect to the infrared absorption image 14). is there. As the image forming apparatus 11 of the present embodiment, as shown in FIG. 4, an example of an image forming apparatus of a system for transferring an image formed on the intermediate transfer body 17 to the base material 12 is shown. In the image forming apparatus of the form shown, the scattered image recording unit 15B is provided upstream of the infrared transfer image recording unit 15A in the transport direction of the intermediate transfer member 17. For this reason, when the toner image formed on the intermediate transfer body 17 is transferred onto the base material 12, the infrared absorption image 14 and the scattered image 16 are sequentially formed on the base material 12.

The intermediate transfer member 17 is rotated in the direction of arrow A in the figure. Although the details will be described later, the scattered image recording unit 15B is based on the third print data input from the image processing device 20, and the scattered image by the toner made of the second recording material containing the scatterer 16A described above. 16 is formed (primary transfer) on the intermediate transfer member 17.
Further, the infrared absorption image recording unit 15A provided downstream of the scattered image recording unit 15B in the rotation direction of the intermediate transfer body 17 is based on the second print data input from the image processing device 20, and The infrared absorption image 14 made of the toner made of the first recording material described above is formed (primary transfer) on the scattered image 16.

  Furthermore, the visible image recording unit 14K, the visible image recording unit 14Y, the visible image recording unit 14M, and the visible image recording unit 14C included in the visible image recording unit 14A are input from the image processing device 20 and will be described later. Based on the print data, visible images of visible toner of each color are sequentially formed (primary transfer) on the intermediate transfer body 17. The order of the colors of the visible image recording unit 14K, the visible image recording unit 14Y, the visible image recording unit 14M, and the visible image recording unit 14C is black (K), yellow (Y), magenta (M), cyan ( The order is not limited to the order of C), and the order is arbitrary, such as the order of yellow (Y), magenta (M), cyan (C), and black (K).

  The base material 12 supplied from the paper feeding device 27 is transported on the paper transport path 31. The substrate 12 is transferred (secondary transfer) to the laminated image 18 and the visible image transferred from the scattered image 16 and the infrared absorption image 14 transferred onto the intermediate transfer body 17. As a result, a visible image is transferred onto the substrate 12, and the infrared absorption image 14 and the laminated image 18 formed by the scattering image 16 formed so as to cover the infrared absorption image 14 are formed on the substrate 12. Will be transferred. The visible image and the laminated image 18 (see FIG. 2) are fixed to the base material 12 by the fixing device 19 and are discharged to the outside along the arrow B.

  Next, each configuration of the image forming apparatus 11 will be described in detail.

The image processing apparatus 20 performs image processing on image data input from the outside such as a personal computer via a network line, a wireless line, or the like, so that the first print data, the second print data, and the first print data 3 is generated and output to the image forming control device 21.
In the present embodiment, the image data input from the outside includes visible image data of a visible image to be formed on the substrate 12 and infrared absorption of the infrared absorption image 14 formed on the substrate 12. The image data is assumed to be included. This visible image is a visible image formed on the substrate 12 and is different from the laminated image 18 described above.

  The visible image data included in this image data includes information indicating the color, dot size, and position (position on the base material 12) of each pixel of the visible image, and is represented by, for example, 8 bits for each of RGB. This image belongs to the RGB space. These visible image data are converted into print data of four colors of yellow (Y), magenta (M), cyan (C), and black (K) by image processing by the image processing device 20, so that the visible image is displayed. The first print data is processed in the recording unit 14A. That is, the first print data is data for forming a visible image on the substrate 12.

  The infrared absorption image data included in the image data is information indicating the position of each pixel, the size of the dot, and the like of the infrared absorption image 14 formed on the substrate 12. The infrared absorption image data is converted into data in a format processed by the infrared absorption image recording unit 15A in the image processing device 20, whereby second print data for printing the infrared absorption image 14 is obtained. It is said. That is, the second print data is data for forming the infrared absorption image 14 on the substrate 12.

  Further, in the image processing device 20, based on the infrared absorption image data, the scattering for forming the scattered image 16 so as to cover the infrared absorption image 14 formed by the infrared absorption image data. Generate image data. The scattered image data is information indicating the position of each pixel, the size of dots, and the like of the scattered image 16 formed on the substrate 12. The scattered image data is converted into data in a format processed by the scattered image recording unit 15B in the image processing device 20 to be third print data for printing the scattered image 16. That is, the third print data is data for forming the scattered image 16 so as to cover the infrared absorption image 14 formed on the substrate 12.

  Based on the first print data, the image formation control device 21 includes light to be described later included in each of the visible image recording unit 14K, the visible image recording unit 14Y, the visible image recording unit 14M, and the visible image recording unit 14C. A pulse signal is output to each of the scanning device 140K, the optical scanning device 140Y, the optical scanning device 140M, and the optical scanning device 140C. Further, the image formation control device 21 outputs a pulse signal to the optical scanning device 140L included in the infrared absorption image recording unit 15A based on the second print data. Further, the image formation control device 21 outputs a pulse signal to the optical scanning device 140I included in the scattered image recording unit 15B based on the third print data.

The scattered image recording unit 15 </ b> B is a device that forms the scattered image 16.
The scattered image recording unit 15B includes an optical scanning device 140I that scans a laser beam in accordance with the third print data input from the image formation control device 21, and an electrostatic discharge generated by the laser beam scanned by the optical scanning device 140I. An image forming apparatus 150I on which a latent image is formed.

  The optical scanning device 140I modulates the semiconductor laser 142I according to the third print data, and emits a laser beam from the semiconductor laser 142I according to the third print data. The laser light emitted from the semiconductor laser 142I is applied to the rotating polygon mirror 146I via the first reflecting mirror 143I and the second reflecting mirror 144I, deflected and scanned by the rotating polygon mirror 146I, and then reflected by the second reflecting mirror 146I. The light is irradiated onto the image carrier 152I of the image forming apparatus 150I through the mirror 144I, the third reflecting mirror 148I, and the fourth reflecting mirror 149I.

  The image forming apparatus 150I includes an image carrier 152I that rotates in the direction of arrow B, a primary charging device 154I that charges the surface of the image carrier 152I, and a static image formed on the image carrier 152I. A developing unit 156I for developing the electrostatic latent image and a removing device 158I are provided.

  In the developing unit 156I, toner composed of the second recording material in the present embodiment, or the toner and a known carrier are held. Then, the toner is supplied from the developing unit 156I to the image holding member 152I. The image carrier 152I is uniformly charged by the charging device 154I, and an electrostatic latent image is formed by the laser light irradiated by the optical scanning device 140I. The electrostatic latent image formed on the image carrier 152I is developed with toner (toner made of the second recording material) supplied from the developing device 156I and transferred to the intermediate transfer member 17. Note that the toner, paper dust, and the like adhering to the image carrier 152I after the transfer are removed by the removing device 158I.

  For this reason, the scattered image recording unit 15B forms (primary transfer) the scattered image 16 on the intermediate transfer body 17 with the toner of the second recording material.

  On the other hand, the infrared absorption image recording unit 15A includes an optical scanning device 140L that scans a laser beam in accordance with the second print data input from the image formation control device 21, and a laser beam that is scanned by the optical scanning device 140L. And an image forming apparatus 150L on which an electrostatic latent image is formed.

  The optical scanning device 140L modulates the semiconductor laser 142L according to the second print data, and emits a laser beam from the semiconductor laser 142L according to the second print data. The laser light emitted from the semiconductor laser 142L is irradiated onto the rotating polygon mirror 146L via the first reflecting mirror 143L and the second reflecting mirror 144L, deflected and scanned by the rotating polygon mirror 146L, and then subjected to the second reflection. The light is irradiated onto the image carrier 152L of the image forming apparatus 150L through the mirror 144L, the third reflecting mirror 148L, and the fourth reflecting mirror 149L.

  The image forming apparatus 150L includes an image carrier 152L that rotates along the direction of arrow B, a primary charging device 154L that charges the surface of the image carrier 152L, and a static image formed on the image carrier 152L. A developing device 156L for developing the electrostatic latent image and a removing device 158L are provided.

  In the developing device 156L, toner composed of the first recording material in the present embodiment, or the toner and a known carrier are held. Then, the toner is supplied from the developing unit 156L to the image holding member 152L. The image carrier 152L is uniformly charged by the charging device 154L, and an electrostatic latent image is formed by the laser light emitted by the optical scanning device 140L. The electrostatic latent image formed on the image carrier 152L is developed with the toner (toner composed of the first recording material) supplied from the developing device 156L and transferred to the intermediate transfer member 17. Note that the toner, paper dust, and the like attached to the image carrier 152L after the transfer are removed by the removing device 158L.

  For this reason, the infrared absorption image recording unit 15A forms (primary transfer) the infrared absorption image 14 on the scattered image 16 on the intermediate transfer body 17 with the toner composed of the first recording material.

  Furthermore, the visible image recording unit 14K, the visible image recording unit 14Y, the visible image recording unit 14M, and the visible image recording unit 14C are devices that form a visible image that is a visible image.

  The visible image recording unit 14 </ b> K includes an optical scanning device 140 </ b> K that scans laser light according to the first print data input from the image processing device 20, and an electrostatic latent image using the laser light scanned by the optical scanning device 140 </ b> K. The image forming apparatus 150K is formed.

  The optical scanning device 140K modulates the semiconductor laser 142K according to the black print data included in the black (K) first print data, and the laser beam LB (K) from the semiconductor laser 142K according to the print data. And exit. The laser beam LB (K) emitted from the semiconductor laser 142K is applied to the rotary polygon mirror 146K via the first reflecting mirror 143K and the second reflecting mirror 144K, and is deflected and scanned by the rotary polygon mirror 146K. The light is irradiated onto the image holding member 152K of the image forming apparatus 150K via the second reflecting mirror 144K, the third reflecting mirror 148K, and the fourth reflecting mirror 149K.

The image forming apparatus 150K includes an image carrier 152K that rotates along the direction of arrow A, a charging device 154K that charges the surface of the image carrier 152K, and an electrostatic latent image formed on the image carrier 152K. A developing device 156K for developing and a removing device 158K are provided.
In the developing device 156K, a conventionally known black toner, or the black toner and a known carrier are held, and the black toner is supplied to the image holding member 152K. The image carrier 152K is charged by the charging device 154K, and an electrostatic latent image is formed by the laser beam LB (K) irradiated by the optical scanning device 140K. The electrostatic latent image formed on the image carrier 152K is developed with the black toner supplied from the developing device 156K and transferred to the intermediate transfer member 17. Note that the toner, paper dust, and the like adhering to the image carrier 152K after the transfer are removed by the removing device 158K.

For the visible image recording unit 14Y, the visible image recording unit 14M, and the visible image recording unit 14C, the black toner contained in the developing device 156K of the visible image recording unit 14K is a known yellow toner and a known magenta toner, respectively. Since the configuration is the same except that the toner is a known cyan toner, a detailed description thereof will be omitted.
In the figure, the constituent members of the visible image recording unit 14Y, the visible image recording unit 14M, and the visible image recording unit 14C are denoted by “K”, which is assigned to each corresponding constituent member in the visible image recording unit 14K. The reference numerals are replaced by “Y”, “M”, and “C”.

  The intermediate transfer body 17 is supported from the inside by a support member 164, a support member 165, a support member 166, a support member 167, a support member 168, and a support member 169, and a drive motor (not shown). As a result, any one support member (for example, the support member 164) is driven to rotate, and thus is driven to circulate in the direction of arrow A. As the intermediate transfer member 17, for example, a flexible synthetic resin film such as polyimide is formed in a band shape, and both ends of the synthetic resin film formed in the band shape are connected by welding or the like to form an endless belt. The formed one is used.

  Further, each of the laminated image recording unit 15 (scattered image recording unit 15B, infrared absorption image recording unit 15A), visible image recording unit 14K, visible image recording unit 14Y, visible image recording unit 14M, and visible image recording unit 14C. A transfer member 162I, a transfer member 162L, a transfer member 162K, a transfer member 162Y, a transfer member 162M, and a transfer member 162C are disposed at positions facing each other through the intermediate transfer member 17, and an image holding member 152I and an image holding member are held. The image formed by the toner formed on the body 152L, the image carrier 152K, the image carrier 152Y, the image carrier 152M, and the image carrier 152C is transferred to the transfer member 162I, the transfer member 162L, the transfer member 162K, the transfer member 162Y, Primary transfer is performed on the intermediate transfer member 17 by the transfer member 162M and the transfer member 162C. Residual toner adhering to the intermediate transfer member 17 is removed by a removing device 189 provided downstream of the secondary transfer position.

  In the paper transport path 31, a paper feed member 180 that takes out the base material 12 from the paper feed device 27, a plurality of support members 181, a support member 182, a support member 183, and a support member 184 are disposed.

  Further, a support member 185 pressed against the support member 168 is disposed at the secondary transfer position on the paper transport path 31, and an image (laminated image 18) of each color toner transferred onto the intermediate transfer body 17. , And a visible image) are secondarily transferred onto the substrate 12 by the pressing force and electrostatic force by the support member 185.

  As a result, the visible image and the laminated image 18 (the infrared absorption image 14 and the scattered image 16) are transferred onto the substrate 12 and conveyed to the fixing device 19 by the conveyance belt 186 and the conveyance belt 187.

  The fixing device 19 is provided with a visible image on the base material 12 and a laminated image 18 (a scattered image 16 so as to cover the infrared absorption image 14 by performing heat treatment and pressure treatment on the base material 12. The toner constituting each of the images is melted and fixed to the recording medium 10.

Next, the functional configuration of the image processing apparatus 20 will be described.
As shown in FIG. 5, the image processing apparatus 20 includes an image data receiving unit 200, a color space conversion unit 202, a first data output unit 206, a conversion unit 210, a second data output unit 212, and a scattered image data generation unit. 214 and a third data output unit 216.

  Each of the above-described components included in the image processing apparatus 20 may be realized by software such as a CPU (Central Processing Unit), a memory, and a program, or may be realized by hardware such as an ASIC (Application Specific Integrated Circuit). May be. Further, the image processing apparatus 20 may be included not only in the image forming apparatus 11 but also in a personal computer, for example.

  In the image processing apparatus 20, the image data receiving unit 200 receives image data from the outside. As described above, the image data includes the visible image data of the visible image formed on the substrate 12 and the infrared absorption image data of the infrared absorption image 14 formed on the substrate 12.

The image data receiving unit 200 outputs visible image data included in the image data received from the outside to the color space conversion unit 202. This visible image data is expressed by, for example, 8 bits for each of RGB, and is image data of an image belonging to the RGB space.
Further, the image data receiving unit 200 outputs the infrared absorption image data included in the image data to each of the conversion unit 210 and the scattered image data generation unit 214.

  The color space conversion unit 202 that has received the visible image data uses the color reproduction characteristics stored in advance to convert the input visible image data (RGB) into CIELAB (L *, a *, b *) as colorimetric values. ) Convert to color space (or CIEXYZ). In addition, the color space conversion unit 202 converts the converted visible image data in the CIELAB color space into visible image data in the YMCK color space of the color system suitable for print processing using the color reproduction characteristics, and the visible image To the data output unit 206 as the first print data. Here, the color reproduction characteristic is information indicating the color reproduction characteristic of an image, for example, an ICC profile. Note that the color space conversion unit 202 may convert the input RGB color space image into YMCK color space image data using a color conversion table stored in advance.

  The data output unit 206 outputs the first print data received from the color space conversion unit 202 to the image formation control device 21.

  On the other hand, in the conversion unit 210 that has received the infrared absorption image data from the image data reception unit 200, the second print data that is the data in the format processed by the infrared absorption image recording unit 15A. And output to the data output unit 212. The data output unit 212 outputs the second print data received from the conversion unit 210 to the image formation control device 21.

Further, in the scattered image data generation unit 214 that has received the infrared absorption image data from the image data reception unit 200, each of the infrared absorption images 14 on the substrate 12 indicated by the received infrared absorption image data. Based on information indicating the position of the pixel and the size of the dot, a dot corresponding to each pixel constituting the scattered image 16 is formed at a position overlapping the dot of each pixel constituting the infrared absorption image 14. Then, scattered image data is created. As described above, the scattered image data is information indicating the position of each pixel, the size of the dot, and the like of the scattered image 16 formed on the substrate 12.
In the present embodiment, in the scattered image data generation unit 214, the dots of the pixels constituting the scattered image 16 are formed so as to overlap the dots of the pixels constituting the infrared absorption image 14. The case where the scattered image data is created will be described. However, the scattered image data may be created so that the scattered image 16 is formed so as to cover the infrared absorption image 14 on the substrate 12. Not limited.
For example, in the scattered image data generation unit 214, each dot constituting the scattered image 16 is composed of dots that overlap the dots of each pixel constituting the infrared absorption image 14 and are larger than the dots of each pixel constituting the infrared absorption image 14. Scattered image data may be created so that pixel dots are formed. Further, the dots of each pixel constituting the scattered image 16 are formed so as to overlap the dots of each pixel constituting the infrared absorption image 14 and cover the periphery of the dots of each pixel constituting the infrared absorption image 14. As described above, scattered image data may be generated.

  The scattered image data generation unit 214 outputs the generated scattered image data to the conversion unit 215. The conversion unit 215 converts the received scattered image data into third print data which is data in a format processed by the scattered image recording unit 15B, and outputs the third print data to the data output unit 216. The data output unit 216 outputs the third print data received from the conversion unit 215 to the image formation control device 21.

  Next, the operation of the image forming apparatus 11 according to the present embodiment will be described.

  First, when the user operates the input / output device 23 to instruct the start of image formation, the processing routine shown in FIG. 6 is executed in the image processing device 20 of the image forming device 11.

  First, in step 100, image data received from outside is read, and in the next step 102, visible image data included in the image data is converted into first print data, thereby creating first print data. To do. This processing is performed by the color space conversion unit 202 described above.

  In the next step 104, infrared absorption image data included in the image data read in step 100 is read, and in the next step 106, second print data is created. This processing is performed by the conversion unit 210.

  In the next step 108, scattered image data is generated from the infrared absorption image data included in the image data read in step 100. This process is performed by the scattered image data generation unit 214. In the next step 110, the third print data is created based on the scattered image data created in step 108. This process is performed by the conversion unit 215.

In the next step 112, the first print data created in step 102, the second print data created in step 106, and the third print data created in step 110 are imaged. The printing process is executed by outputting to the formation control device 21.
The image formation control device 21 that has received the first print data, the second print data, and the third print data controls the visible image recording unit 14A based on the first print data, and the second print data. The infrared absorption image recording unit 15A is controlled based on the first print data, and the scattered image recording unit 15B is controlled based on the third print data. Thereby, the scattered image 16 formed by the scattered image recording unit 15B is transferred onto the intermediate transfer body 17, and the infrared absorption image 14 formed by the infrared absorption image recording unit 15A is transferred onto the intermediate transfer body 17. Transferred onto the scattered image 16. Further, the visible image formed by the visible image recording unit 14 </ b> A is transferred onto the intermediate transfer body 17.
As a result, an infrared absorption image 14 is formed on the substrate 12 and a scattering image 16 is formed so as to cover the infrared absorption image 14. In addition, a visible image (not shown) is also formed on the substrate 12.

  In the above-described embodiment, an example in which an electrophotographic image forming apparatus is used as an apparatus for forming the infrared absorption image 14 and the scattered image 16 on the substrate 12 has been described. Needless to say, it may be formed by an inkjet printer, or by an apparatus such as letterpress printing, offset printing, flexographic printing, gravure printing, or silk printing.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

―Adjustment of infrared absorbing colorant―
The following color materials were prepared as color materials having infrared absorptivity.
<Adjustment of infrared absorbing colorant 1 (perimidine-based squarylium dye)>
4.843 g (98%, 30.0 mmol) of 1,8-diaminonaphthalene, 3.886 g (98%, 30.2 mmol) of 3,5-dimethylcyclohexanone, 10 mg (0.053 mmol) of p-toluenesulfonic acid monohydrate ) And 45 ml of toluene were heated with stirring in a nitrogen gas atmosphere and refluxed for 5 hours. Water formed during the reaction was removed by azeotropic distillation. After completion of the reaction, the dark brown solid obtained by distilling toluene was extracted with acetone, purified by recrystallization from a mixed solvent of acetone and ethanol, dried, and then 7.48 g of brown solid (yield 93 .6%). The analysis result by ¹ H-NMR spectrum (CDCl ₃ ) of the obtained brown solid is shown below.

¹ H-NMR spectrum (CDCl ₃ ): δ = 7.25, _7.23 , _7.22 , _7.20 , _7.17 , 7.15 (m, 4H, H _arom ); 6.54 (d × d, J ₁ = 23.05 Hz, J ₂ = 7.19 Hz, 2H, H _arom ); 4.62 (br s, 2H, 2 × NH); 2.11 (d, J = 12.68 Hz, 2H, CH ₂ ); 1.75, 1.71, 1.70, 1.69, 1.67, 1.66 (m, 3H, 2 × CH, CH ₂ ); 1.03 (t, J = 12. 68 Hz, 2H, CH ₂ ); 0.89 (d, J = 6.34 Hz, 6H, 2 × CH ₃ ); 0.63 (d, J = 11.71 Hz, 1H, CH ₂ )

  A mixture of the above brown solid 4.69 g (17.6 mmol), 3,4-dihydroxycyclobut-3-ene-1,2-dione 913 mg (8.0 mmol), n-butanol 40 ml and toluene 60 ml was mixed with nitrogen gas. The mixture was heated in the atmosphere with stirring and refluxed for 3 hours. Water formed during the reaction was removed by azeotropic distillation. After completion of the reaction, most of the solvent was distilled into an atmosphere of nitrogen gas, and 120 ml of hexane was added while stirring the resulting reaction mixture. The resulting black brown precipitate was suction filtered, washed with hexane, and dried to give a black blue solid. This solid was washed successively with ethanol, acetone, 60% aqueous ethanol, ethanol and acetone to obtain 4.30 g (yield 88%) of the target compound (black blue solid).

The obtained dye compound was identified by spectroscopic methods such as infrared absorption spectrum (KBr tablet method), ¹ H-NMR (DMSO-d ₆ ), FD-MS, elemental analysis, visible near infrared absorption spectrum and the like. Identification data is shown below. The visible near infrared absorption spectrum is shown in FIG. As a result of identification, it was confirmed that the obtained compound was a perimidine-based squarylium dye represented by the structural formula (I).

Infrared absorption spectrum (KBr tablet method):
ν _max = 3487, 3429, 3336 (NH), 3053 (= C—H), 2947 (CH ₃ ), 2914, 2902 (CH ₂ ), 2864 (CH ₃ ), 2360, 1618, 1599, 1558, 1541 ( C = C ring), 1450, 1421, 1363 (CH ₃ , CH ₂ ), 1315, 1223, 1201 (CN), 1163, 1119 (C—O—), 941, 924, 822, 783, 715 cm ^{− 1
1} H-NMR spectrum (DMSO-d ₆ ): δ = 10.52 (m, 2H, NH); 7.80, 7.78 (d, 2H, H _arom ); 7.35, 7.33 (m , 2H, _Harom ); 7.25 (m, 2H, NH); 6.82, 6.80, 6.78 (m, 4H, _Harom ); 6.74, 6.72, 6.52, 6.50 (m, 2H, H _arom ); 2.17 (m, 5H, CH ₂ ); 1.91 (m, 3H, CH ₂ ); 1.71 (m, 2H, CH, CH ₂ ); 1.15, 1.12 (m, 4H, CH ₂ ); 0.92, 0.91 (m, 12H, 4 × CH ₃ ); 0.66 (m, 2H, CH ₂ )
Mass spectrum (FD): m / z = 610 (M ⁺ , 100%), 611 (M ⁺ +1, 47.5%)

Elemental analysis:
C: 78.6% (actual value), 78.66% (calculated value)
H: 6.96% (actual value), 6.93% (calculated value)
N: 9.02% (actual value), 9.17% (calculated value)
O: 5.42% (actual value), 5.24% (calculated value)

Visible and near infrared absorption spectrum (see FIG. 7):
λ _max = 809 nm (in tetrahydrofuran solution)
ε _max = 1.68 × 10 ⁵ M ⁻¹ cm ⁻¹ (in tetrahydrofuran solution)

(Pigmentation treatment)
Next, 51 g of the obtained perimidine-based squarylium dye, 25 g of 12 mass% sodium dodecylbenzenesulfonate aqueous solution, and 425 g of water were put into a bead mill processing apparatus (manufactured by Ashizawa Finetech, Minicer), and 485 g of 0.1 mmφ beads, The operation was performed for 3 hours at a speed of 12 m / s. When the particle size distribution of the collected berimidine-based squarylium pigment (hereinafter referred to as “(A) particles”) was measured, the median diameter was 65.9 nm.

<Adjustment of infrared absorbing colorant 2 (perimidine-based squarylium dye)>
50 mg of perimidine-based squarylium dye particles (hereinafter referred to as “raw material”) before the pigmentation treatment in the infrared absorbing colorant 1 and 1 mL of tetrahydrofuran (THF) and 10 g of zirconia beads having a diameter of 1 mm are placed in a ball mill container for 1 hour. Milling was performed. Water was added to the ball mill container and filtered through a 50 nm filter to collect perimidine-based squarylium pigment particles (hereinafter referred to as “(B) particles”).

(Measurement of powder X-ray diffraction)
About perimidine-based squarylium pigment particles (hereinafter referred to as “raw material”), pigment (A) in infrared absorbing colorant 1 and (B) particles in infrared absorbing colorant 2 before pigmentation treatment in Test Example X Using an X-ray diffraction apparatus (“D8 DISCOVER”, manufactured by Bruker AXS Co., Ltd.), powder X-ray diffraction was measured by X-ray irradiation of λ = 1.5405 mm with a Cu target. The obtained powder X-ray diffraction spectra are shown in FIGS.

  From FIG. 8, (A) the particles are diffracted into 22.1 °, 23.2 °, 19.9 °, 24.9 °, and 17.7 ° in descending order of Bragg angle (2θ ± 2 °). A peak is shown, indicating that the crystal system is the same as the raw material. On the other hand, from FIG. 9, (B) particles have a Bragg angle (2θ ± 2 °), and in descending order of strength, 22.6 °, 24.2 °, 8.9 °, 17.1 °, 18.4 °. Shows a diffraction peak, indicating that the crystal system is different from that of the raw material and (A) particles.

<Adjustment of infrared absorbing color material 3>
The pigment compound represented by the following formula (VII) was subjected to particle formation treatment by the following method.

  40 mg of the dye compound represented by the above formula (VII) was dissolved in 30 mL of THF, and the solution was poured into 2000 mL of distilled water cooled with ice using a microsyringe to perform reprecipitation. Several minutes later, the mixture was returned to room temperature, and the precipitate was filtered through a 50 nm filter, washed with distilled water, and vacuum dried to recover the reprecipitated dye compound (hereinafter referred to as “(C) particles”). Regarding the particle size of the (C) particles, the median diameter d50 was about 90 nm. (C) For the particles, a powder X-ray diffraction spectrum was obtained by X-ray irradiation of λ = 1.5405 mm with a Cu target in the same manner as the infrared absorbing color material 2, and almost no diffraction peaks derived from crystals were observed. The particles (C) obtained by the precipitation method were amorphous.

<Adjustment of infrared absorbing color material 4>
In the infrared-absorbing color material 3, 40 mg of particles (C) obtained by the reprecipitation method, 5 mL of hexane, and 10 g of agate beads having a diameter of 1 mm were placed in a ball mill container and milled for 8 hours. Water was added to the ball mill container, and the mixture was filtered with a 50 nm filter to recover the pigmented pigment compound (hereinafter referred to as “(D) particles”). (D) The particle diameter of the particles was such that the median diameter d50 was about 90 nm. (D) About the particle | grains, when the powder X-ray-diffraction spectrum measured by the X-ray irradiation of (lambda) = 1.5405cm was obtained with Cu target similarly to the infrared absorption color material 2, the Bragg angle | corner (2 (theta) ± 0.2 degree) ) At least 11.9 °, 13.1 °, 15.4 °, 19.0 °, 20.4 °, 23.0 °, 23.9 °, 24.6 °, 26.4 ° The result which shows a peak was obtained and (D) particle | grains had high crystallinity.

-Preparation of slurry-
(A) particles adjusted as the infrared absorbing color material 1, (B) particles adjusted as the infrared absorbing color material 2, (C) particles adjusted as the infrared absorbing color material 3, and adjusted as the infrared absorbing color material 4 For each of the particles (D), 9.2 mg was ultrasonically dispersed together with 46 μl of a 12% by weight aqueous sodium dodecylbenzenesulfonate solution and 5.52 ml of distilled water to prepare a slurry (ultrasonic power: 4-5 W, 1 / 4 inch horn use, irradiation time 30 minutes). The sample concentration in the slurry was 0.165% by mass.

--Readability--
Mixture of (A) particle slurry (sample concentration 0.165% by mass) 40.4 μL, 40% by weight latex (polystyrene acrylate n-butyl) solution 15 μL, and 5 g of distilled water prepared as infrared absorbing colorant 1 Was dispersed with an ultra turrax to obtain a mixed slurry. A PAC flocculant is added to the obtained mixed slurry to obtain a pseudo toner dispersion, which is filtered through a 220 nm filter, air-dried, and thermocompression bonded (120 ° C.), TMA = 4 g / m ² , pigment amount per unit area PMA = A latex patch for evaluation having 0.04 g / m ² (corresponding to a pigment content of 1% by mass in the toner) was prepared.
The visible near infrared absorption spectrum of the obtained latex patch was measured with a spectrophotometer U-4100 manufactured by Hitachi, Ltd., and the result is shown in FIG. Further, R (initial reflectance at 850 nm) in the above formula (III) was determined and shown in Table 1.

  In place of the (A) particles in the slurry, the (B) particles adjusted as the infrared absorbing color material 2, the (C) particles adjusted as the infrared absorbing color material 3, and the infrared absorbing color material 4 were adjusted ( D) By using each of the particles, a mixed slurry is prepared by the same method as that for the particles (A) to prepare a latex patch for evaluation, a visible near infrared absorption spectrum is measured, and R in the above formula (III) Asked. The evaluation results are shown in FIG.

--Invisibility--
(A) particles adjusted as the infrared absorbing color material 1, (B) particles adjusted as the infrared absorbing color material 2, (C) particles adjusted as the infrared absorbing color material 3, and adjusted as the infrared absorbing color material 4 (E) ΔE in the above formula (II) was determined for the latex patch for evaluation prepared using each of the particles (D). The evaluation results are shown in Table 1.
In addition, the measurement of this (DELTA) E was obtained by measuring using a reflection spectral densitometer (X-lite 939 by the X-Rite Co., Ltd.).

The evaluation criteria for invisibility were as follows.
A: 0 ≦ ΔE ≦ 6
B: 6 <ΔE ≦ 16
C: ΔE> 16

--Evaluation of light resistance--
(A) particles adjusted as the infrared absorbing color material 1, (B) particles adjusted as the infrared absorbing color material 2, (C) particles adjusted as the infrared absorbing color material 3, and adjusted as the infrared absorbing color material 4 (D) Light irradiation (light source: xenon lamp, irradiance: 540 W / m ² = 100 k lux, no UV cut filter) was performed on the latex patch for evaluation prepared using each of the particles (D). .
And light resistance was evaluated by measuring a reflectance of 850 nm with a spectrophotometer U-4100 made by Hitachi, Ltd. every 12 hours. FIG. 11 shows the relationship between the reflectance of the latex patch for evaluation and the light irradiation time.
The evaluation criteria for readability and light resistance were as follows. The evaluation results are shown in Table 1.

Evaluation criteria for readability:
A (particularly good readability): R ≦ 25
B (good readability): 25 <R ≦ 40
C (Readable): R> 40

Evaluation criteria for light resistance:
A (light resistance is particularly good): Reflectance @ 850 nm (%) ≦ 44 after 24 hours of light irradiation
B (good light resistance): 44 <reflectance after 24 hours of light irradiation @ 850 nm (%) ≦ 66
C (with light resistance): Reflectance @ 850 nm (%) after light irradiation 24 hours> 66

As described above, the (A) particles and (B) particles prepared as the infrared absorbing color material 1 and the infrared absorbing color material 2 are invisible compared with the infrared absorbing color material 3 to the infrared absorbing color material 4. Thus, the readability and light resistance were greatly improved while maintaining the stability.
For this reason, if infrared absorption color material 1 and infrared absorption color material 2 are used as organic infrared absorption color materials, the first recording material is adjusted, and an infrared absorption image is formed, another infrared absorption is achieved. Compared with the case where a color material is used, it can be said that the readability by infrared light is further improved while the invisibility of the infrared absorption image itself is maintained.

―Adjustment of scatterers―
The following scatterers were prepared as scatterers included in the scattered image (second recording material).
<Adjustment of scatterer 1>
Titanium oxide (CR60 manufactured by Ishihara Sangyo Co., Ltd.) was used as the scatterer. It was 210 nm when the volume average particle diameter D50 of this scatterer 1 was measured.

[Example A, Comparative Example A]
(Example A1)
―Infrared absorption image formation―
As a base material, Fuji Xerox Co., Ltd. C2 paper (white) was prepared.

  And the infrared absorption image was formed on this base material with the following method.

First, using the infrared absorbing color material 1 adjusted as described above, a toner having a content of the infrared absorbing color material 1 of 1.3% by mass was prepared.
Specifically, after adding 98 mol% dimethyl sebacate, 2 mol% dimethyl-5-sulfonate sodium, 100 mol% ethylene glycol, and 0.3 parts dibutyltin oxide as a catalyst in a heat-dried three-necked flask The air in the container was made inert with nitrogen gas by depressurization, and the mixture was stirred and refluxed at 180 ° C. for 5 hours with mechanical stirring. Thereafter, the temperature was gradually raised to 230 ° C. under reduced pressure, and the mixture was stirred for 2 hours. When it became viscous, it was air-cooled to stop the reaction, and then dried to synthesize a crystalline polyester resin. It was Tg = 64 degreeC, Mn = 4600, Mw = 9700 of the crystalline polyester resin obtained by molecular weight measurement (polystyrene conversion) by gel permeation chromatography.

・ Crystalline polyester resin: 28 parts ・ Amorphous polyester resin: 59 parts (Linear polyester by condensation polymerization of terephthalic acid / bisphenol A ethylene oxide adduct / cyclohexanedimethanol Tg = 62 ° C., Mn = 4,000, Mw = 12,000)
・ Infrared absorbing colorant 1 ・ ・ ・ ・ 1.3 parts ・ Paraffin wax HNP9 (melting point 75 ° C .: made by Nippon Seiki) ・ ・ ・ ・ ・ ・ 11.7 parts

Each of the above components is sufficiently premixed with a Henschel mixer, melt kneaded with a biaxial roll mill, cooled and finely pulverized with a jet mill, and further classified twice with a wind classifier. A toner of Infrared absorbing colorant 1 having a thickness of 0 μm and a density of 1.3% was produced.
This toner was output by the image forming apparatus 11 to form an image with an image area ratio of 100% (TMA = 3.5 g / m ² ).

-Formation of scattered images-
A scattering image was formed on the formed infrared absorption image using the scatterer 1 so as to cover the infrared absorption image.

First, using the scatterer 1 adjusted as described above, a toner having a scatterer 1 content of 30% by mass was prepared.
Specifically, after adding 98 mol% dimethyl sebacate, 2 mol% dimethyl-5-sulfonate sodium, 100 mol% ethylene glycol, and 0.3 parts dibutyltin oxide as a catalyst in a heat-dried three-necked flask The air in the container was made inert with nitrogen gas by depressurization, and the mixture was stirred and refluxed at 180 ° C. for 5 hours with mechanical stirring. Thereafter, the temperature was gradually raised to 230 ° C. under reduced pressure, and the mixture was stirred for 2 hours. When it became viscous, it was air-cooled to stop the reaction, and then dried to synthesize a crystalline polyester resin. It was Tg = 64 degreeC, Mn = 4600, Mw = 9700 of the crystalline polyester resin obtained by molecular weight measurement (polystyrene conversion) by gel permeation chromatography.

· Crystalline polyester resin ··· 20 parts · Amorphous polyester resin ··· 42 parts (linear polyester Tg by condensation polymerization of terephthalic acid / bisphenol A ethylene oxide adduct / cyclohexanedimethanol Tg = 62 ° C., Mn = 4,000, Mw = 12,000)
・ Titanium oxide ・ ・ ・ ・ ・ ・ 30 parts

Each of the above components is sufficiently premixed with a Henschel mixer, melt-kneaded with a twin-screw roll mill, cooled and finely pulverized with a jet mill, and further classified twice with an air classifier. A white toner having a thickness of 0 μm and a colorant concentration of 30% was prepared.
Next, a scattering image (TMA = 14.7 g / m ² ) having an image area ratio of 100% was formed so as to cover the infrared absorption image using the toner adjusted using the scatterer 1.

<Evaluation>
―Reflectance evaluation―
In Example A1, an infrared absorption image and a scattered image were formed in this order, and thus, the laminated image formed on the substrate was irradiated with light in a wavelength region of 400 nm to 500 nm from the scattered image side. The reflectance was measured using a U-4100 spectrophotometer manufactured by HITACHI. The measurement results are shown in FIG.

―Evaluation of shielding properties of colors in the wavelength range from 400nm to 500nm―
First, with respect to an infrared absorption image (Comparative Example A1 described later) in which no scattering image is formed in the laminated image formed in Example A1, the reflectance for light in the wavelength region of 400 nm to 500 nm is expressed as HITACHI. It was 48% (minimum reflectance of an infrared absorption image) when it measured using the U-4100 spectrophotometer by a company, and the reflectance in the absorption peak wavelength (-420 nm) was calculated | required.

Next, the laminated image formed in Example A1 was irradiated with light from the scattered image side, and the reflectance for light in the wavelength region of 400 nm to 500 nm was measured using a U-4100 spectrophotometer manufactured by HITACHI. The reflectance at the absorption peak wavelength (˜420 nm) was measured and found to be 86% (minimum reflectance of the laminated image).
And the shielding factor of the color of the wavelength range of 400 nm or more and 500 nm or less was computed using following formula (1). The results are shown in Table 2.

Formula (1)
Color shielding ratio (%) in the wavelength region of 400 nm to 500 nm
= 100- (Minimum reflectance of laminated image with respect to light in wavelength region of 100-400 nm to 500 nm) / (Minimum reflectance of infrared absorption image with respect to light in wavelength region of 100-400 nm to 500 nm)

―Reading evaluation by infrared light (wavelength range of 700nm to 900nm) ―
First, for the infrared absorption image (Comparative Example A1 to be described later) in which the scattered image is not formed in the laminated image formed in Example A1, the reflectance for light in the wavelength region of 700 nm to 900 nm is expressed as HITACHI. It was 16% (minimum reflectance of infrared absorption image) when it measured using the U-4100 spectrophotometer by a company and the reflectance in the absorption peak wavelength was calculated | required.

Next, the laminated image formed in Example A1 was irradiated with light from the scattered image side, and the reflectance for light in the wavelength region of 700 nm to 900 nm was measured using a U-4100 spectrophotometer manufactured by HITACHI. The reflectance at the absorption peak wavelength was measured and found to be 40% (minimum reflectance of the laminated image).
And the shielding rate of the color of the wavelength range of 700 nm or more and 900 nm or less was computed using following formula (2). The results are shown in Table 2.

Formula (2)
Shielding ratio of color in wavelength region of 700 nm to 900 nm = 100− (minimum reflectance of laminated image with respect to light in wavelength region of 100 to 700 nm to 900 nm) / (red to light in wavelength region of 100 to 700 nm to 900 nm) Minimum reflectance of external absorption image)

  As shown in Table 2, the color shielding rate in the wavelength region of 400 nm to 500 nm is 73%, which is higher than 29% of the color shielding rate in the wavelength region of 700 nm to 900 nm. It can be seen that the wavelength region of 400 nm to 500 nm is shielded more effectively.

―Evaluation of invisibility of laminated images―
The color density in the visible region of the white base material used in Example A1 and the color density in the visible region of the laminated image formed on the base material were determined using an X-Rite 939 spectral densitometer (manufactured by X-Rite). ). The measured values (hereinafter referred to as “OD values”) are shown in Table 2.

Moreover, the color coordinate (L ^* , a ^* , b ^* ) of the laminated image was measured using an x-rite 939 spectral densitometer (manufactured by X-Rite). Further, the square root of saturation c ^* = (square of (a ^* ) + square of (b ^* )) was calculated. The results are shown in Table 2.

Based on the measured values, the invisibility of the laminated image was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 2.
G1: When OD <1.0 and c ^* <2.0.
G2: When OD <1.2 and c ^* <5.0.
G3: When OD <1.3 and c ^* <9.0.

(Example A2 to Example A4)
The scattered image of the layered images formed in Example A1, the TMA scattering image to be ^{formed, 7.8g / m 2, 5.2g /} m 2, except that the respective 2.8 g / ^{m 2,} the An infrared absorption image and a scattering image were formed in this order on the substrate under the same conditions as in Example A1, and evaluation was performed in the same manner as in Example A1.
The evaluation results of the reflectance are shown in FIG. 12, and the other evaluation results are shown in Table 2.

(Comparative Example A1)
Except that the scattered image in the laminated image prepared in Example A1 was not formed (that is, the TMA of the scattered image was set to 0.0 g / m ² ) on the substrate under the same conditions as in Example A1. Then, an infrared absorption image was formed and evaluated in the same manner as in Example A1. The evaluation results are shown in Table 2.

As shown in Table 2, the result that the invisibility (evaluation reference value or c ^* ) was improved in the case with the laminated image (Example A1-A4) as compared with the case without the laminated image (Comparative Example A1) was obtained. . At the same time, since the color shielding rate in the wavelength region of 700 nm to 900 nm is lower than the color shielding rate in the wavelength region of 400 nm to 500 nm, as shown in Example B and Comparative Example B below, infrared absorption images The result was that the readability of the code signal was maintained.

[Example B, Comparative Example B]
(Example B1)
―Infrared absorption image formation―
As a base material, Fuji Xerox Co., Ltd. C2 paper (white) was prepared.

  And the infrared absorption image was formed on this base material with the following method.

On the substrate, the toner shown in Example A1 was output by the image forming apparatus 11 to form a QR code with an infrared absorption image (TMA = 3.5 g / m ² ).

-Formation of scattered images-
A scattered image was formed on the formed infrared absorption image in the same manner as in Example A1, using the scatterer 1 so as to cover the infrared absorption image. The scattered image had a TMA of 13.4 g / m ² .

―Evaluation of infrared reading code-
In Example B1, an infrared absorption image and a scattering image are formed in this order, so that the laminated image formed on the substrate has an infrared sensitivity with a wavelength region of 700 nm to 900 nm from the scattering image side. The infrared absorption image (QR code) was read using a flat bed scanner (IR-6000, manufactured by iMeasure Co., Ltd.). Then, the reading performance of the read image data was evaluated using QR code reading evaluation software (QR checker manufactured by Denso Wave). Table 3 shows the evaluation results of the decode grade (A is the best among the six stages from A to F).

(Example B2 to Example B3)
With respect to the scattered image in the laminated image formed in Example B1, the TMA of the formed scattered image was set to 7.9 g / m ² and 3.3 g / m ² , respectively, under the same conditions as Example B1. On the substrate, an infrared absorption image (QR code) and a scattered image were formed in this order, and evaluation was performed in the same manner as in Example B1. The evaluation results are shown in Table 3.

(Comparative Example B1)
Except that the scattered image in the laminated image formed in Example B1 was not formed (that is, the TMA of the scattered image was set to 0.0 g / m ² ), red was formed on the substrate under the same conditions as in Example B1. An external absorption image (QR code) was formed and evaluated in the same manner as in Example B1. The evaluation results are shown in Table 3.

  As shown in Table 3, the result that Example B with the laminated image maintains the readability (decoding) of the QR code hit by the infrared absorption image is obtained as in Comparative Example B without the laminated image. It was. This improves the invisibility by shielding the color in the wavelength region of 400 nm to 500 nm with the laminated image layer, and at the same time maintains the readability of the code signal by the infrared absorption image of 700 nm to 900 nm. It is shown that.

DESCRIPTION OF SYMBOLS 10 Recording medium, 11 Image forming apparatus, 12 Base material, 14 Infrared absorption image, 16 Scattering image, 15A Infrared absorption image recording part, 15B Scattering image recording part

Claims (6)

A substrate;
An infrared absorption image formed on the substrate and formed by a first recording material containing an organic infrared absorbing colorant excluding carbon black; and
A scattered image formed by a second recording material provided to cover the infrared absorption image and including a scatterer having a volume average particle size of 200 nm or more and 400 nm or less;
A recording medium comprising:   The recording medium according to claim 1, wherein the substrate is white.   The recording medium according to claim 1, wherein the scattered image is white. The recording medium according to any one of claims 1 to 3, wherein the organic infrared absorbing colorant is a perimidine-based squarylium dye represented by the following structural formula (I).

  The perimidine-based squarylium dye represented by the structural formula (I) has a Bragg angle (2θ ± 0.2 °) of at least 17 in a powder X-ray diffraction spectrum measured by X-ray irradiation at a wavelength of 1.5405 mm with a Cu target. The recording medium according to claim 4, which exhibits diffraction peaks at .7 °, 19.9 °, 22.1 °, 23.2 °, and 24.9 °. A first recording apparatus for recording an infrared absorption image on a substrate with a first recording material containing an organic infrared absorbing colorant excluding carbon black;
A second recording apparatus for recording a scattered image with a second recording material containing a scatterer having a volume average particle size of 200 nm or more and 400 nm or less so as to cover the infrared absorption image;
An image forming apparatus.