JP2001294785A - Image-forming material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-forming material using a near infrared absorbing pigment which has no visibility by the naked eye and enables easy image reading with the use of near infrared rays. SOLUTION: The image-forming material comprise a near infrared light absorbing pigment which substantially does not absorb rays in the visible wavelength range of 400-750 nm and has an absorption band having a molar extinction coefficient of >=108 cm2/mol in the near infrared wavelength range of 750-1,000 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a near-infrared absorbing dye that does not substantially absorb visible light but absorbs infrared light, and forms optically identifiable code patterns and marks such as inspection marks. To an image forming material.

[0002]

2. Description of the Related Art In recent years, barcodes as optically readable code patterns have been widely used in distribution management systems. Further, a document including an image and a visible or invisible two-dimensional digital code is used for security management, embedding of Internet information and voice, and the like, and the added value of the document is improved.

When a code is recorded as visible information, there is an advantage that a region to be swept at the time of reading is easy to understand, but there is a problem that a document or the like becomes unsightly.

On the other hand, a document or the like in which a code is recorded as invisible information has a high use value in terms of security management and the like. As a method of recording invisible information, there are a method of embedding the information in an image or a document in a visible wavelength region such as a monduro mask method and a density pattern method in a situation where it is difficult to determine the information, and a silicon light receiving element (CCD, etc. ) Can be detected but cannot be discriminated by human eyes.
There is a method using an image forming material having absorption in the near infrared light region of 00 nm.

In the former, a method of printing code information at a high resolution is required in order not to degrade image quality, and a reading device is required to have a resolution equal to or higher than that.

On the other hand, in the latter case, if there is only an excellent image forming material having an absorption only in the near-infrared region, the visible information is recorded by using an image forming material having no absorption in the near-infrared wavelength region. Since the invisible information can be read without being influenced by each other, it is possible to print both of them in an overlapping manner, and a large amount of information can be recorded on a recording medium. Further, by using a semiconductor laser or a light emitting diode emitting at any wavelength in the range of 650 to 1000 nm as a light source for optical reading and using a general-purpose light receiving element having high spectral sensitivity to near infrared light, The invisible information can be read easily and with high sensitivity.

A method of forming a pattern using an ink having absorption in the near infrared light region is disclosed in, for example, JP-A-63-1.
16286, JP-A-3-154187, JP-A-3-154
227378, JP-A-3-275389, JP-A-5
No. 93160.

[0008]

However, dyes having an absorption band in the near infrared region used in these publications, such as cyanine dyes, phthalocyanine dyes, naphthoquinone dyes, anthraquinone dyes, and zirol dyes In addition, triphenylmethane-based dyes and the like have relatively strong absorption even in the visible region, and are not necessarily transparent in a visible wavelength range.

On the other hand, among molecules which form a complex with a rare earth metal or the like, those having an absorption band in the near infrared wavelength region from the absorption wavelength of the rare earth metal atom have been reported [for example, JP-A-8-209110]. And JP-A-9-77507]. These have relatively low absorption in the visible region and excellent transparency, but have a broad absorption band in the near-infrared wavelength region and a low extinction coefficient. Therefore, when used as an image forming material, it is necessary to increase the content of the dye, which not only increases the cost, but also decreases the transparency,
Originally, there was a problem that absorption in a weak visible region could not be ignored.

In view of the above, in order to provide an image which is transparent in the visible wavelength range and has high contrast in the invisible near-infrared wavelength range, it has an absorption band showing a large absorbance only in the near-infrared wavelength region. It is desired to provide an image forming material.

Therefore, an object of the present invention is to provide a near-infrared region (75
Another object of the present invention is to provide a new image forming material that has absorption only at 0 to 1000 nm) and hardly absorbs visible light. That is, an object of the present invention is to provide an image forming material using a near-infrared absorbing dye which is invisible to the naked eye and can be easily read using near-infrared light.

[0012]

In general, an organic dye has an absorption in a visible wavelength range by electronic excitation of a π-electron conjugate system in which a double bond and a single bond are repeated. Therefore, as the length of the continuous π-electron conjugate system becomes longer, in other words, as the number of participating atoms increases, the absorption wavelength becomes longer. This longer wavelength also depends on the molecular structure. For example, when a cyanine dye is compared with a squarylium dye or a croconium dye, the latter has a greater degree of longer wavelength for the same π-conjugated system length [Jurgen Fabian,
Hiroyuki Nakazumi, and M
asaru Matsuoka, “Near-Infr
ared Absorbing Dyes ”, Che
m. Rev .. 1992, 92, 1197-12
26].

On the other hand, in the present invention, it is also important that the absorption band is in a long wavelength region, but a dye having almost no absorption in the visible light region is required. As a result of repeated studies, the present inventors have found that cyclic compounds represented by phthalocyanine dyes and the like, and compounds having relatively bulky portions such as compounds in which three or more benzene rings are continuously bonded, It has been found that a non-linear compound has a large absorption in the visible light region even if the absorption wavelength is increased. Polymethine dyes having a structure in which a double bond and a single bond are repeated, particularly dyes having a structure of [donor]-[acceptor]-[donor] in the molecule, which are relatively linearly arranged, The present invention has been found to have an absorption band in the region exceeding 750 nm and show almost no absorption in the visible light region.

The present invention does not substantially absorb light in the visible light wavelength range of 400 to 750 nm and has a wavelength of 750 to 1000 nm.
Molar absorption coefficient of 10 ⁸ cm ² / mol in the near infrared wavelength region of
An image forming material comprising a near infrared absorbing dye having the above absorption band is provided.

400-750 nm of the near infrared absorbing dye
Has a molar extinction coefficient of 2 × 10 ⁷ c in the visible light wavelength region.
It is preferably less than m ² / mol.

Examples of such near infrared absorbing dyes include polymethine dyes, especially dyes having a [donor]-[acceptor]-[donor] structure in the molecule. The [acceptor] portion is preferably a croconium group represented by the following structural formula.

[0017]

Embedded image

Further, the image forming material of the present invention may further contain a stabilizer having an absorption band on a longer wavelength side than the absorption band of the near infrared absorbing dye. As the stabilizer, an organometallic complex compound can be used.

The above-mentioned image forming material is an electrophotographic toner,
It can be used as ink for inkjet printers or ink for letterpress, offset, flexo, gravure or silk printing.

The image forming material of the present invention has a content of 750 to 100.
It has a sharp absorption band in the range of 0 nm. An invisible information pattern formed by using this image forming material is formed by using a semiconductor laser (for example, a gallium arsenide semiconductor laser) or a light emitting diode (for example, an infrared light emitting diode) as an irradiation light source for detection, and using ordinary silicon. By using a light-receiving element using the above, reading can be easily performed. When white light is used as the light source, it can be identified as a sharp absorption signal by using an optical system that does not transmit the visible light wavelength region and has an optical filter that transmits the absorption wavelength of the near-infrared absorbing dye. it can. As the optical filter, a very inexpensive one used for a remote controller or the like can be used.

Further, since the image forming material of the present invention has the same printing characteristics as other visible light absorbing materials, it is possible to record the same fine code information as the spatial resolution in each printing method.

The invisible information pattern includes all information including a code pattern. Examples of the code pattern include a one-dimensional or two-dimensional barcode.

Further, since the invisible information pattern formed by the image forming material of the present invention has no visibility, it may be recorded so as to overlap the area where the visible information is recorded, or may be recorded with the visible information. It may be recorded on an area other than the area, for example, on the back surface. Even when the invisible information pattern formed by the present invention is recorded on the back side of thin paper, the pattern does not affect the quality of the front side.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The image-forming material of the present invention is 400 to
Does not substantially absorb light in the visible wavelength region of 750 nm,
A near infrared absorbing dye having an absorption band of a molar absorption coefficient of 10 ⁸ cm ² / mol or more in a near infrared wavelength region of 750 to 1000 nm is contained.

400-750 nm of this near infrared absorbing dye
Has a molar extinction coefficient of 2 × 10 ⁷ c in the visible light wavelength region.
It is preferably less than m ² / mol.

Examples of such near-infrared absorbing dyes include polymethine dyes having a structure (—CH ＝ CH—) _{n in} which a double bond and a single bond are repeated. In particular, a cyanine dye, a squarylium dye, and a croconium dye, among which a dye having a structure of [donor]-[acceptor]-[donor] in the molecule, in which these are arranged relatively linearly, are preferable. Such organic near-infrared absorbing dyes include those represented by the following general formulas (1) to (5).

[0027]

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In the formula, Ar ¹ represents ^one of the following structures.

[0029]

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In the formula, Ar ² represents any of the following structures.

[0031]

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X ^1- is F, Cl, Br, I, ClO
₄ , BF _6, etc., a monovalent anion, n represents an integer of 1 to 4, R ¹ represents C _m H _{2m + 1} , m represents an integer of 0 to 6, Y ¹ represents O , S, Se, C, R ³ to ⁹ are H,
_{Cl, F, OH, SO 3} -, C e H 2e-1, OC e H 2e + 1, C
_{e H 2e + 1, C e} H 2e OH, C e H 2e OC f H 2f + 1, indicates,
e represents an integer of 1 to 18, and f represents an integer of 1 to 6. When Y ¹ is C, C _g H _{2g + 1} (g is 1 to 6)
May be substituted with an alkyl group.

Among these, the dyes represented by the general formulas (3) to (5) are preferable, and the croconium dyes represented by the general formula (4) or (5) are more preferable.
The croconium dye represented by can have a sufficiently long wavelength of the absorber even if the molecular structure is compact,
It is particularly preferable since it has high solubility in an organic solvent or an aqueous mixed organic solvent and dispersibility in a resin polymer, and has a high color development degree.

The croconium dye represented by the general formula (4) is illustrated below, but the infrared absorbing dye usable in the present invention is not limited to these.

[0035]

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When the image forming material of the present invention contains a solvent or a binder resin described below, the near-infrared absorbing dye is used to improve the solubility and dispersibility in these solvents and the binder resin. It is preferable to introduce a substituent that is compatible with the solvent and the binder resin. For example, when the image forming material of the present invention contains water, the near infrared absorbing dye preferably has a hydrophilic substituent, and when the image forming material of the present invention contains an organic solvent or a binder resin. Preferably, the near infrared absorbing dye preferably has a hydrophobic substituent such as an alkyl group.

The average particle size of the organic near-infrared absorbing dye is 0.0
It is preferably from 01 to 1 μm. The image forming material of the present invention is a printing method suitable for printing a code pattern,
When used as an ink for injection printing, a toner for electrophotographic printing, or an ink for offset printing, the average particle diameter of the organic near-infrared absorbing dye is 0.001 μm.
It is preferably about 0.1 μm. The print thickness or print thickness obtained by the above method is usually about 1 to 2 μm.
m, which is at most about 3 μm. By setting the average particle diameter of the infrared absorbing dye within the above range, printing unevenness can be suppressed. Also, when writing code information with a fine pattern, the smaller the particle size, the better, and ideally, it is desirable to be in a molecular dispersion state.

Although the above-mentioned polymethine dyes are basically excellent in light resistance, the degree of photodegradation is somewhat higher than that of phthalocyanine dyes having higher stability. The main cause of photodeterioration is that excited dye molecules form singlet oxygen, and the singlet oxygen and the dye molecules are decomposed by reaction. Therefore, in order to further improve the light resistance, the image forming material of the invention preferably contains a stabilizer. The stabilizer needs to receive energy from the organic near-infrared absorbing dye in the excited state, and preferably has an absorption band on a longer wavelength side than the absorption band of the near-infrared absorbing dye. Such stabilizers include organometallic complex compounds. Stabilizers that can be preferably used in the present invention include the following, but stabilizers that can be used in the present invention are not limited to these.

[0039]

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[0040] In the formula, R ¹⁴ ~ ¹⁸ is H, NH _2, OH, N
_{(C h H 2h + 1)} 2, OC h H 2h + 1, C h H 2 h-1, C
_{h H 2h + 1, C h} H 2h OH, shows the _{C h H 2h OC i H 2i} + 1, h
Represents an integer of 1 to 18, and i represents an integer of 1 to 6. X ² and Y ² represent O, S, and Se, respectively.
X ² and Y ² may be the same or different. Z is N
represents a transition metal such as i, Co, Mn, Pd, Cu, and Pt.

Among them, a stabilizer having the following structure is particularly preferably used.

[0042]

Embedded image

It is preferable that the stabilizer is hardly decomposed by singlet oxygen and has high compatibility with the organic near-infrared absorbing dye. The concentration of the stabilizer is preferably about 1/10 to 2 times the weight of the organic near-infrared absorbing dye.

The image-forming material of the present invention can be applied to aqueous inks such as ink-jet inks, oil-based inks such as letterpress, offset, flexo, gravure or silk printing inks, and toners used in electrophotographic recording devices.

When the image forming material of the present invention is an aqueous ink, the image forming material of the present invention can contain water. Further, the image forming material of the present invention may further contain a water-soluble organic solvent in order to prevent drying of the ink and improve the permeability.

As the water, ion exchange water, ultrafiltration water,
Pure water and the like. Examples of the organic solvent include polyhydric alcohols such as ethylene glycol, diethylene glycol, polyethylene glycol and glycerin: N-alkylpyrrolidones: esters such as ethyl acetate and amyl acetate: lower alcohols such as methanol, ethanol, propanol and butanol. Classes: methanol, butanol,
Glycol ethers such as phenol ethylene oxide or propylene oxide adducts are exemplified. One or more organic solvents may be used. The organic solvent is selected in consideration of hygroscopicity, moisture retention, solubility of the organic near-infrared absorbing dye, permeability, ink viscosity, freezing point, and the like.

The content of the organic solvent in the inkjet ink is preferably 1 to 60% by weight. The concentration of the organic near-infrared absorbing dye in the inkjet ink is preferably in the range of 0.05 to 5% by weight, and this concentration is adjusted according to the optical density required after printing.

In order to satisfy various conditions required for the system of the ink jet recording apparatus, the image forming material of the present invention can contain additives conventionally known as components of ink. Such additives include p
H adjuster, specific resistance adjuster, antioxidant, preservative, fungicide, metal sequestering agent and the like. As a pH adjuster,
Examples thereof include alcohol amines, ammonium salts, and metal hydroxides. In addition, examples of the specific resistance adjusting agent include organic salts and inorganic salts. Examples of the sequestering agent include a chelating agent.

Further, the image forming material of the present invention can be used in such a manner that polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, styrene-acrylic acid resin, styrene-maleic acid can be used to such an extent that the fogging nozzle is not blocked or the ink ejection direction is not changed. A water-soluble resin such as an acid resin may be contained.

When the image forming material of the present invention is an oil-based ink, the image forming material of the present invention may contain a polymer or an organic solvent. As the polymer, generally, natural resins such as proteins, rubbers, celluloses, shellac, copal, starch, rosin, etc .; vinyl resins, acrylic resins, styrene resins, polyolefin resins, novolac phenol resins, etc. And a thermosetting resin such as a urea resin, a melamine resin, a polyurethane resin, an epoxy, and an unsaturated polyester.

Examples of the organic solvent include those described above.

When the image-forming material of the present invention is an oil-based ink, the image-forming material further comprises a plasticizer for improving the flexibility and strength of the printed film, and a solvent for adjusting the viscosity and improving the drying property. , A drying agent, a viscosity modifier, a dispersant, and various reactants.

The concentration of the organic near-infrared absorbing dye in the oil-based ink is preferably in the range of 0.05 to 5% by weight, and this concentration is adjusted according to the required optical density after printing.

When the image forming material of the present invention is a toner, the image forming material contains a binder resin. Examples of the binder resin used include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene, and isoprene; vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl esters such as vinyl butyrate;
Α of methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, etc.
-Homopolymers or copolymers of vinyl ethers such as methylene aliphatic monocarboxylic esters, vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, and vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone; Illustrative, particularly typical binder resins are polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, Styrene-maleic anhydride copolymer, polyethylene, polypropylene and the like can be mentioned. further,
Polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like can also be used as the binder resin.

When the image forming material of the present invention is a toner, the image forming material may further contain a charge controlling agent and an offset preventing agent, if necessary.

The charge controlling agent includes those for positive charging and those for negative charging, and quaternary ammonium compounds for positive charging. For negative charging, a metal complex of alkyl salicylic acid, a resin-type charge control agent containing a polar group, and the like can be given.

As the anti-offset agent, low molecular weight polyethylene, low molecular weight polypropylene and the like are used.

The concentration of the organic near-infrared absorbing dye in the toner is preferably 0.02 to 10% by weight, and 0.05 to 5% by weight.
Is more preferred. This density is adjusted according to the required optical density after printing.

When the image forming material of the present invention is a toner, inorganic powder particles or organic particles are used as an external additive for improving fluidity, powder preservability, triboelectric charge control, transfer performance and cleaning performance. It may be added to the toner surface.

Examples of the inorganic powder particles include known ones, for example, silica, alumina, titania, calcium carbonate, magnesium carbonate, calcium phosphate, cerium oxide and the like. A known surface treatment may be applied to the inorganic powder particles according to the purpose.

Examples of the organic particles include emulsion polymers containing vinylidene fluoride, methyl methacrylate, styrene-methyl methacrylate, and the like, and soap-free polymers.

When the image forming material of the present invention is a toner, the average particle size is generally preferably from 3 to 12 μm, more preferably from 4 to 8 μm. If the average particle size exceeds 12 μm, the reproduction of fine lines is inferior. If the average particle size is less than 3 μm, the surface area per unit weight of the toner becomes large, and it becomes difficult to control charging and fluidity, and a stable image may not be obtained.

The toner which is the image forming material of the present invention comprises 1
It may be used alone as a component developer or as a two-component developer in combination with a carrier.

As the carrier, a known carrier can be used. For example, a resin-coated carrier having a resin coating layer on a core material can be mentioned. Conductive powder or the like may be dispersed in this resin coating layer.

[0065]

The present invention will be further described below with reference to examples. Example 1 A solution was prepared by dissolving the croconium dye (dye 4-1) in chloroform, and the absorption spectrum was measured. The result is shown in FIG. The molar extinction coefficient at 831 nm, which is the absorption peak, is 2.325 × 10 ⁸ cm ²
/ Mol (2.325 × 10 ⁵ / M · cm), which was the highest absorbance of the dye. 400 ~
The molar extinction coefficient in the wavelength range of 700 nm was 1/20 or less of that in the near infrared region, and it was confirmed that the visibility of this dye was low and the transparency was extremely high. Croconium dye (dye 4-1) 0.1 part by weight Polyester resin 99.9 parts by weight (Ethylene oxide adduct of bisphenol A-terephthalic acid copolymer, Tg 65 ° C, Mn 4000, Mw 10,000) The above components are kneaded with an extruder. After pulverizing with a jet mill, the particles were classified with an air classifier to obtain an average particle size of 8.0 μm.
m particles were obtained. 0.5 wt% of silica (R972, manufactured by Nippon Aerosil Co., Ltd.) was added to the particles using a Henschel mixer to prepare a near infrared absorbing toner. This toner was loaded into an electrophotographic recording apparatus, and a solid square pattern of 10 cm square was printed on plain paper. Although the printed portion was hardly colored, the reflectance of the printed region at 830 nm was 1/5 that of the non-printed region when the reflection spectrum was measured with a spectrophotometer. Example 2 A solution was prepared by dissolving the croconium dye (dye 4-2) in chloroform, and the absorption spectrum was measured. The same absorption spectrum as that in FIG. 1 was obtained. It was confirmed that the transparency was high.

0.1 part by weight of this dye, 80 parts by weight of pure water,
An aqueous ink was prepared by mixing 10 parts by weight of isopropyl alcohol and 10 parts by weight of ethylene glycol. This was loaded into an ink jet printer, and a 10 cm square was printed on the ink jet dedicated paper. The printed square could hardly be discerned visually. The reflection spectra of the printed portion and the non-printed portion were measured with a spectrophotometer. The results are shown in FIG. 830n
The reflectance of the paper (non-printed part) at m was about 80%, while the reflectance of the printed part was only 16%. That is, it was found that detection by near-infrared light can be performed with a contrast of 5 times or more. Further, the density per unit area of the dye molecules applied on the paper surface to obtain this printing density was only 3 × 10 ⁻⁹ mole / cm ⁻² . This value was at least one order of magnitude lower than the concentration of the dye in the ink using a dye having an absorption band in the visible region, which was generally used, and the high performance of the obtained aqueous ink was confirmed.

The water-based ink was printed with a 10 cm square pattern printed with black ink (manufactured by Epson Corporation). An area where only black ink is printed,
The reflection spectrum of the area where the aqueous ink was printed on a black pattern was measured. The results are shown in FIG. Black ink has almost no optical properties in the near infrared region,
The reflectance at 0 nm was 79%. On the other hand, in the region where the croconium dye was printed together with black, the absorption spectrum of the black ink and the absorption spectrum of the croconium dye hardly overlapped. That is, even if a normal printing (black and white or color) image and an image formed by the image forming material of the present embodiment are superimposed on the printing surface of the printed matter and printed,
It was confirmed that the near-infrared image could be read without any problem (without being affected by the visible image). Example 3 In the preparation of particles before addition of an external additive, a nickel complex compound represented by the following formula (absorption peak wavelength: 850 nm): 0.1
A near-infrared absorbing toner was produced in the same manner as in Example 1 except that the weight part was further added. A solid 10 cm square pattern was printed on plain paper by an electrophotographic recording apparatus loaded with the toner. Although the printed portion was hardly colored, the reflectance of the printed region at 830 nm was 1/5 that of the non-printed region when its reflection spectrum was measured with a spectrophotometer. This confirmed that the nickel complex compound mixed as a stabilizer did not inhibit the spectral characteristics of the near-infrared absorbing toner at all. Further, the printed paper was placed under irradiation of a 1.2 kW xenon lamp, and a change in reflectance over time was measured.
As a result, in the square pattern using the near-infrared absorbing toner of Example 1 which did not contain the stabilizer, the reflectance was increased by about 10% in 10 days, whereas the example containing the stabilizer was not increased. No change in reflectance was observed in the pattern formed with the near infrared absorbing toner of No. 3. Example 4 0.1 part by weight of a croconium dye (dye 4-1), 48 parts by weight of an acrylic resin, 40 parts by weight of isopropyl alcohol, and 12 parts by weight of ethyl acetate were uniformly mixed to prepare an oil-based ink. Using this, gravure printing is performed and 10c
An m-square pattern was obtained. The reflectance at 830 nm of the print area was measured by a spectrophotometer, and was 1/4 (about 16%) that of the non-print area.

[0068]

According to the present invention, infrared absorption codes such as infrared absorption code patterns and infrared absorption detection marks which have no absorption in the visible light region and have a sharp absorption peak in the near infrared light wavelength region of 750 to 1000 nm. Marks can be formed.

[Brief description of the drawings]

FIG. 1 shows an absorption spectrum of a croconium dye used in Example 1 in a chloroform solution.

FIG. 2 shows the reflection spectra of the paper used in Example 2 and the printing region of the near-infrared absorbing ink.

FIG. 3 shows a reflectance spectrum of a black printed portion obtained in Example 2 and a region where black and near-infrared absorbing ink are printed.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) G03G 9/09 G03G 9/08 361 (72) Inventor Masahiro Takagi 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. In-company (72) Inventor Izumi Iwasa 430 Green Tech Nakai, Nakai-cho, Ashigara-Kami, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. Term (reference) 2C056 FC01 2H005 AA29 CA21 EA10 2H086 BA55 BA60 4J039 AB02 AB07 AB08 AB11 AD01 AD03 AD05 AD09 AE02 AE03 AE04 AE05 AE06 BC07 BC09 BC10 BC11 BC14 BC20 BC50 BC53 BC54 BC55 BC64 BE01 BE02 GA11 GA06 EA03

Claims (8)

[Claims] 1. A near-infrared light having a molar absorption coefficient of 10 ⁸ cm ² / mol or more in a near-infrared light wavelength region of 750 to 1000 nm without substantially absorbing light in a visible light wavelength region of 400 to 750 nm. An image forming material comprising an infrared absorbing dye. 2. The near infrared absorbing dye of 400 to 750 n
The molar extinction coefficient in the visible light wavelength region of m is 2 × 10 ^7
2. The image forming material according to claim 1, wherein the density is less than cm ² / mol. 3. The image forming material according to claim 1, wherein the near infrared absorbing dye is a polymethine dye. 4. The image forming material according to claim 1, wherein the near-infrared absorbing dye has a [donor]-[acceptor]-[donor] structure in the molecule. . 5. The image forming material according to claim 4, wherein the [acceptor] portion is a croconium group represented by the following structural formula. Embedded image 6. The image forming apparatus according to claim 1, further comprising a stabilizer having an absorption band on a longer wavelength side than the absorption band of the near-infrared absorbing dye. material 7. The image forming material according to claim 6, wherein the stabilizer is an organometallic complex compound. 8. The image forming material according to claim 1, which is an electrophotographic toner, an ink for an ink jet printer, or an ink for letterpress, offset, flexo, gravure, or silk printing.