JP2008291167A - Planographic ink composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planographic ink composition containing a near-infrared light absorbing agent and a fluorescent brightening agent, capable of increasing invisibility of infrared light absorbing ink having a coloring property in a visible light region and an ink composition capable of forming micronized and thinned information pattern. <P>SOLUTION: The planoographic ink composition containing the near-infrared light absorbing agent and the fluorescent brightening agent comprises at least one fluorescent brightening agent having excitation wavelength at 300 nm to 400 nm wavelength and having emission wavelength at 400 nm to 550 nm wavelength and at least one near-infrared light absorbing agent having spectral absorption maximum wavelength at 750 nm to 1,100 nm wavelength. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink composition having absorption in the near infrared wavelength region. More specifically, the present invention can accurately detect an information pattern in the near-infrared wavelength region, and is useful for forming an information carrying sheet useful for discriminating the authenticity of securities and the like, and an ink composition useful for forming the information pattern. Related to things.

  Conventionally, various functions have been applied to various certificates to prevent falsification and counterfeiting. For example, under normal conditions, it is not possible to identify with the naked eye, and by using a liquid crystal, conductive material, or magnetic material that has a function that can be identified only by a specific operation, a function to prevent collation and tampering is added. Yes. These methods, for example, have coloring properties in the ink itself, so that the visual prevention effect is insufficient under normal conditions with the naked eye, peeling, damage or tampering during use is easy, The operation was not easy, and it was not always satisfactory.

  In recent years, a detection method using infrared absorption has been used as a relatively easy method, and has also been applied to barcode printing. For example, an information pattern is printed on a predetermined portion such as securities using a printing ink containing an infrared absorbing material such as carbon black, and the presence / absence of the information pattern is read by an infrared reading device to determine authenticity. However, since the carbon black has light absorptivity even in the visible light region, the presence or absence of an information pattern can be visually determined. For this reason, even if the information pattern is formed, it is identified, and the accuracy of authenticity determination is lowered.

  In general, as infrared absorbers, acetylacetone metal chelate compounds, anthraquinone compounds, naphthoquinone compounds, diamine cisethylenethiolatonickel derivatives, aromatic diamine metal complexes, aliphatic diamine metal complexes, aromatic dithiol metal complexes, aliphatic dithiols Metal complexes, phthalocyanine derivatives and the like are known. Patent Document 1 discloses a machine-readable information carrying sheet in which an information pattern is printed with a white infrared reflective ink on an information carrying sheet medium containing an infrared absorbing substance in a sheet-like substrate.

  Patent Document 2 discloses an infrared ray having a surface having infrared reflectivity and a color similar to the surface and containing divalent iron ions and / or divalent copper ions and phosphate white crystal powder. A mechanically readable information carrying sheet with an absorbent printing ink layer is disclosed.

  Further, in Patent Document 3 and Patent Document 4, there is a machine-readable information-carrying sheet having an information pattern formed of an ultraviolet-curable infrared absorbing ink containing an infrared absorbing material on an infrared reflective substrate. It is disclosed.

  Also, in general, high-grade printing paper such as offset printing and gravure printing is applied to paper containing a fluorescent whitening agent together with a pigment and an aqueous binder in order to increase the whiteness of the coated paper in order to increase its commercial value. Various compositions have been studied and used. For example, coumarin derivatives, stilbene derivatives, bisoxazole derivatives, benzoxazole derivatives, naphthalimide derivatives, xanthene derivatives, trimethyldihydropyridine derivatives, coeroxene derivatives and the like are known as fluorescent brighteners.

  Further, Patent Document 5 discloses, as a method for preventing whiteness loss in paper and pulp, N, N-dialkylhydroxylamine, ester-substituted, amide-substituted or thio-substituted N, N-dialkylhydroxylamine or N, N Disclosed are methods for enhancing resistance to yellowing by adding dibenzylhydroxylamine, or salts thereof and other adjuvants. Patent Document 6 discloses a method for producing a highly transparent film that prevents yellowing of an ultraviolet-absorbing film used in fields such as medical drugs and foods. As a mechanism for suppressing this yellowing, the fluorescent whitening agent is excited by light energy in the ultraviolet region, and since the emission wavelength at the time of deactivation is in the visible light region, the color is not visually confirmed. to cause.

These inks having infrared absorptivity or reflectivity are obtained by dispersing or dissolving an infrared reflection or absorption substance powder, and materials that efficiently absorb infrared rays are such that the powder itself is in the visible light region. The information-carrying sheet printed with ink that exhibits color due to absorption in and dispersed or dissolved therein may be able to visually confirm the information pattern. Furthermore, in recent years, there is an increasing number of cases where miniaturization or thinning of information patterns and dot patterns is required. In some cases, the reading sensitivity cannot be maintained without increasing the content of infrared reflecting or absorbing materials. As a result, inks with higher invisibility effects have been demanded.
JP-A-6-191137 JP-A-6-247087 Japanese Patent Laid-Open No. 7-68982 JP 2003-326879 A Japanese translation of PCT publication No. 2002-528657 JP 2005-305745 A

  The present invention provides a lithographic ink composition comprising a near-infrared absorber and a fluorescent whitening agent, which can increase the invisibility of an infrared-absorbing ink having colorability in the visible light region. With the goal. Another object of the present invention is to provide an information-carrying sheet that is difficult to identify visually and is useful for preventing forgery and alteration, and an ink composition useful for obtaining this sheet. To do. Another object of the present invention is to provide an ink composition capable of forming an information pattern that has been refined and thinned.

  The present invention relates to a lithographic ink composition comprising a near-infrared absorber and a fluorescent brightening agent. As a first aspect of the present invention, a fluorescence having an excitation wavelength of 300 nm to 400 nm and an emission wavelength of 400 nm to 550 nm. The present invention relates to a lithographic ink composition containing at least one or two brightening agents and at least one or two or more near-infrared absorbers having a spectral absorption maximum wavelength at 750 nm to 1100.

  As a second invention, the fluorescent whitening agent described in the first invention is contained in an amount of 0.01% to 20% by weight, and a near infrared absorber is contained in an amount of 0.1% to 20% by weight. The present invention relates to a lithographic ink composition.

  Furthermore, the third invention relates to a lithographic ink composition, wherein the lithographic ink composition described in the first or second invention is an offset printing ink with water.

  The fourth invention relates to a lithographic ink composition, wherein the lithographic ink composition described in the first or second invention is a waterless offset printing ink.

  Furthermore, the fifth invention relates to the lithographic ink composition described in the first to fourth inventions, wherein the lithographic ink composition is an oxidation polymerization type ink.

  The sixth invention relates to the lithographic ink composition described in the first to fifth inventions, wherein the lithographic ink composition is an actinic ray curable ink.

  Further, the seventh invention is composed of a base material having an infrared reflective surface, and fine elements formed on the surface of the base material by the lithographic ink according to the first to sixth inventions and difficult to recognize visually. And an information carrying sheet that is optically readable.

  The eighth invention relates to the information carrying sheet according to the seventh invention, wherein the information pattern is composed of fine dot-like elements.

  The ninth invention relates to the information carrying sheet according to the seventh or eighth invention, wherein the information pattern is composed of dots having an average diameter of 1 to 100 μm and a thickness of 0.5 to 2 μm.

  With the ink composition of the present invention, an invisible property is enhanced by extinguishing absorption in the visible light region of the near-infrared absorber by light emission of the fluorescent whitening agent, and an ink composition that can be detected with high sensitivity by a near-infrared sensor. Can be provided. Furthermore, the coating film using the ink composition provided by the present invention is highly transparent, hardly colored, and cannot be visually confirmed.

  Hereinafter, a preferred embodiment of the present invention will be specifically described.

  In the present invention, the fluorescent whitening agent is preferably added to the lithographic ink composition in an amount of 0.01 to 20% by weight, more preferably 0.5 to 15% by weight. When the addition amount exceeds 20% by weight, efficient light emission cannot be obtained due to the aggregation effect of the fluorescent brightening agent itself, and the ink fluidity deteriorates, which is not preferable in terms of printability. In particular, good light emission is obtained at 0.5 to 15% by weight and fluidity is also obtained. If it is less than 0.01% by weight, sufficient light emission cannot be obtained, and the color of the near infrared absorber cannot be erased.

  Moreover, it is preferable to add 0.1-20 weight% of near-infrared absorbers to a lithographic ink composition, and it is more preferable to add 1-15 weight%. If the addition amount exceeds 20% by weight, the fluidity of the ink deteriorates due to the aggregation of the dispersed particles, which is not preferable in terms of printability. In particular, good ink fluidity can be obtained at 1 to 15% by weight. If it is less than 0.1% by weight, there is a possibility that sufficient absorption for detection by an infrared sensor cannot be obtained. As the ink composition, various printing inks conventionally used can be used.

  The ink composition of the present invention may be colored in the visible light region if it is difficult to distinguish from the infrared reflective surface of the substrate by visual observation, at least in the form of an information pattern, but is preferably colorless and transparent. . If the color is difficult to identify, the visual identification is further difficult. Therefore, it is preferable that the ink composition is difficult to distinguish from the substrate surface not only in the form of a fine information pattern but also in color. Such an ink composition is preferably in the visible light region and has the same color (same or similar color) as the infrared reflective base material surface, or is colorless to pale. Note that the same color and light color means that it can be visually identified with the base material in color, and the hue, saturation, and / or lightness are the same or similar (or similar) to the color of the base material. ) In many cases.

  In the present invention, it is preferable to use a lithographic ink as the ink in order to accurately form a thin information pattern having a uniform thickness.

The planographic ink may be an off-wheel ink or the like, but is preferably a sheet-fed ink. In addition, when a pattern is formed with lithographic printing ink using dampening water, if the outline is not clear, or a dot or void is formed in the dot by fine water droplets, a non-uniform pattern is formed, and pattern accuracy May decrease. Therefore, waterless lithographic ink is preferable in order to increase the accuracy of the information pattern. Compared with general lithographic inks that use fountain solution, waterless lithographic inks can form information patterns with a uniform thickness and sharp contours, and the contrast of the boundary area between the substrate and the information pattern can be reduced. As a result, the fine pattern can be formed thinly and uniformly with high accuracy. In many cases, the lithographic ink is usually an oxidation polymerization type ink containing a drying oil or a semi-drying oil (unsaturated oil), but it is an actinic ray curable ink such as an ultraviolet curable ink or a penetrating drying ink. It does not matter. In the present invention, actinic rays mainly indicate ultraviolet rays and electron beams.
In the oxidation polymerization type lithographic ink, a binder resin, fats and oils, a high boiling point solvent, a dryer, a drying inhibitor, an auxiliary agent, and the like can be used depending on the type.

  Examples of the binder resin for the oxidation polymerization type lithographic ink include, for example, phenolic resins (phenolic resins, rosins, cured rosins, rosin-modified phenolic resins using rosins such as polymerized rosins, etc.), maleic acid resins (rosin-modified). Maleic acid resins, rosin ester resins, etc.), alkyd resins or modified alkyd resins, petroleum resins, etc., which can be used alone or in combination of two or more.

  The oils and fats are vegetable oils and compounds derived from vegetable oils. For example, in triglycerides of glycerin and fatty acids, at least one fatty acid is a fatty acid having at least one carbon-carbon unsaturated bond, and those triglycerides. And fatty acid monoesters obtained by ester reaction of saturated or unsaturated alcohols, or fatty acid monoesters obtained by direct ester reaction of vegetable oil fatty acids and monoalcohols, and ethers.

  Typical vegetable oils are: Asa seed oil, flaxseed oil, Eno oil, Oitsika oil, olive oil, cacao oil, kapok oil, kayak oil, mustard oil, kyounin oil, tung oil, kukui oil, walnut oil, poppy oil, sesame oil , Safflower oil, Japanese radish seed oil, soybean oil, daikon oil, camellia oil, corn oil, rapeseed oil, niger oil, nuka oil, palm oil, castor oil, sunflower oil, grape seed oil, gentian oil, pine seed oil Cottonseed oil, palm oil, peanut oil, dehydrated castor oil, and the like.

  The high boiling point solvent is a crude oil-derived solvent (petroleum solvent) having an aromatic hydrocarbon content of 1% by weight or less. As the petroleum solvent, a petroleum solvent having an aniline point of 70 ° C. to 110 ° C. and a boiling point of 230 ° C. or more is suitable. When the aniline point is less than 70 ° C., the ability to dissolve the resin is too high, the ink viscosity becomes too low, and the background stain resistance becomes insufficient. Also, when the aniline point exceeds 110 ° C., the ability to dissolve the resin is too low, the ink viscosity becomes too high, the ink fluidity becomes poor, and the ink tends to deposit on the rollers, plates, and blankets. Therefore, it is not preferable.

  The dryer is an oxidative polymerization catalyst that promotes oxidative polymerization. Acetic acid, propionic acid, butyric acid, isopentanoic acid, hexanoic acid, 2-ethylbutyric acid, naphthenic acid, octylic acid, nonanoic acid, decanoic acid, 2-ethyl Hexanoic acid, isooctanoic acid, isononanoic acid, lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, neodecanoic acid, versatic acid, secanoic acid, tall oil fatty acid, linseed oil fatty acid, soybean oil fatty acid, dimethylhexanoic acid , 3,5,5-trimethylhexanoic acid, metal salts of organic carboxylic acids such as dimethyloctanoic acid, such as calcium, cobalt, lead, iron, manganese, zinc, zirconium, salts, etc. Compounds can be used and these to promote printing ink surface and internal curing A plurality of them can be used in combination as appropriate.

  Further, the drying inhibitor is a polymerization inhibitor having an inhibitory effect on the oxidative polymerization reaction, and hydroquinone derivatives represented by hydroquinone, 2-methylhydroquinone, 2-tert-butylhydroquinone, etc. -Denotes phenolic compounds typified by tert-butyl-4-hydroxytoluene and the like, vitamin compounds having an antioxidant action typified by ascorbic acid, tocopherol, etc., and these are arbitrarily used alone or in combination of two or more. Can be used.

  As auxiliary agents, anti-friction agents, anti-blocking agents, slip agents, pigment dispersants, carnauba wax, wax wax, lanolin wax, montan wax, paraffin wax, microcrystalline wax, natural wax, Fischer-Tropsch synthetic wax, Synthetic waxes such as polyethylene wax, polypropylene wax, polytetrafluoroethylene wax and polyamide wax, silicone additives, leveling agents and the like can be used as appropriate.

  In the ultraviolet curable lithographic ink, a binder resin, a monomer, an oligomer, a photopolymerization initiator, an auxiliary agent, and the like can be used depending on the type.

  Examples of the binder resin for the ultraviolet curable lithographic ink include polyvinyl chloride, poly (meth) acrylic acid ester, epoxy resin, polyester resin, polyurethane resin, cellulose derivatives (for example, ethyl cellulose, cellulose acetate, nitrocellulose), vinyl chloride. -Vinyl acetate copolymer, polyamide resin, polyvinyl acetal resin, diallyl phthalate resin, alkyd resin, rosin modified alkyd resin, petroleum resin, urea resin, synthetic rubber such as butadiene-acrylonitrile copolymer, etc. They can be used alone or in combination of two or more. In either case, a resin that is soluble in a monomer having an ethylenically unsaturated double bond is used.

Moreover, as a monomer, monofunctional or polyfunctional (meth) acrylates are mentioned, The viscosity of an ink composition can be adjusted by using these suitably.
As the oligomer, alkyd acrylate, epoxy acrylate, urethane-modified acrylate, or the like is used.

  In addition, one or two or more photopolymerization initiators can be appropriately added to the ultraviolet curable ink as a component that promotes the curing action.

  As photopolymerization initiators, benzophenone, 4-methylbenzophenone, 4,4-diethylaminobenzophenone, diethylthioxanthone, 2-methyl-1- (4-methylthio) phenyl-2-morpholinopropan-1-one, 4-benzoyl -4′-methyldiphenyl sulfide, 1-chloro-4-propoxythioxanthone, isopropylthioxanthone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxy-cyclohexyl-phenyl ketone, bis-2, 6-dimethoxybenzoyl-2,4,4-trimethylpentylphosphine oxide, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2, 2-dimethyl-2-hydroxyacetate Enone, 2,2-dimethoxy-2-phenylacetophenone, 2,4,6, -trimethylbenzyl-diphenylphosphine oxide, 2-benzyl-2-dimethylamino-1- (monoforinophenyl) -butane-1- ON etc. are mentioned. A photo accelerator such as p-dimethylaminobenzoic acid ethyl ester or pentyl-4-dimethylaminobenzoate may be used in combination with the photopolymerization initiator.

  As auxiliary agents, anti-friction agents, anti-blocking agents, slip agents, pigment dispersants, carnauba wax, wax wax, lanolin wax, montan wax, paraffin wax, microcrystalline wax, natural wax, Fischer-Tropsch synthetic wax, Synthetic waxes such as polyethylene wax, polypropylene wax, polytetrafluoroethylene wax and polyamide wax, silicone additives, leveling agents and the like can be used as appropriate.

  Furthermore, extender pigments such as calcium carbonate, barium sulfate, alumina white, and silica may be added to the lithographic ink. For example, the average particle diameter of the extender pigment is often about 0.01 to 1 μm (preferably 0.01 to 0.1 μm), and calcium carbonate is often used. If necessary, the lithographic ink for forming the information pattern may be an infrared transmitting or absorbing pigment (for example, a white pigment such as titanium oxide, disazo yellow, etc.) unless the base material and the information pattern can be visually identified. A yellow pigment such as brilliant carmine 6B, a blue pigment such as phthalocyanine blue, a black pigment, particularly a black colorant prepared with a plurality of colorant components using subtractive color mixing). .

  In the present invention, as the optical brightener, coumarin derivatives, stilbene derivatives, bisoxazole derivatives, benzoxazole derivatives, naphthalimide derivatives, xanthene derivatives, trimethyldihydropyridine derivatives, coeroxene derivatives, N, N-dialkylhydroxylamines, ester substitutions, An amide-substituted or thio-substituted N, N-dialkylhydroxylamine or N, N-dibenzylhydroxylamine or a salt thereof is shown, and these can be used alone or in combination of two or more.

  In the present invention, the near-infrared absorber includes metal chelate compounds of acetylacetone, anthraquinone compounds, naphthoquinone compounds, diamine cisethylenethiolatonickel derivatives, aromatic diamine metal complexes, aliphatic diamine metal complexes, aromatic dithiol metal complexes. , Aliphatic dithiol metal complexes, phthalocyanine derivatives and the like, which can be used alone or in combination of two or more.

  In addition, when there is little content of a near-infrared absorber, the consistency of a lithographic ink, a viscosity characteristic, etc. will change and the precision of an information pattern may fall. Therefore, the lithographic ink containing a near-infrared absorber may not contain extender pigments depending on the type of near-infrared absorber, but it is preferable to combine the near-infrared absorber and extender pigment. The extender pigment may have near infrared absorptivity or may not have near infrared absorptivity. The content of extender is 1 to 30% by weight, preferably 5 to 25% by weight, based on the whole lithographic ink. The weight ratio of the near infrared absorber to the extender is 5/95 to 50/50, preferably 10/90 to 45/55, more preferably 15/85 to 40/60, and 20/80 to 30/70 is particularly preferred.

  In the lithographic ink, the ratio of each component is 1 to 15 parts by weight of a near infrared absorbent, 5 to 25 parts by weight of an extender pigment, 10 to 40 parts by weight of a binder resin, 20 to 30 parts by weight of fats and oils, and 20 to 30 parts by weight of mineral oil. The ratio is preferably about 100 parts by weight, including additives such as auxiliaries.

  The lithographic ink has a viscosity of 100.0 Pa · s or less, preferably 40.0 Pa · s to 80.0 Pa · s, at 25 ° C. and a shear rate of 100 / s with a cone plate viscometer. When the viscosity is larger than the above numerical value, the fluidity and transferability are lowered, and the whole printed matter tends to be rough. Further, since the tack value of the ink increases with the viscosity, paper peeling and paper separation failure are likely to occur. The waterless lithographic ink preferably has a viscosity of 150 Pa · s or less at 25 ° C. and a shear rate of 100 / s with a cone plate viscometer, more preferably 60.0 Pa · s to 120 Pa · s. When the viscosity is larger than the above value, a tendency similar to that of the lithographic ink appears, and poor walling is likely to occur, leading to a decrease in printing quality such as missing dots, and a problem occurs in reading accuracy with respect to the infrared sensor. On the other hand, if the value is smaller than the above value, background stains are likely to occur, thereby obscure the information pattern formed on the printing paper surface, not only reducing the reading accuracy by the infrared sensor, but also hindering the printing itself. Become.

  The reflectance of the infrared rays by the information pattern is, for example, 0 to 60%, preferably 0 to 50%, more preferably about 0 to 40% with respect to the irradiated infrared rays (for example, infrared rays having a wavelength of 850 to 950 nm). .

  The information pattern can be composed of various forms of fine patterns that are difficult to recognize or identify visually. The shape may be a dot shape or a fine line shape.

  Since such an information pattern is difficult to identify visually, the portion applied to the substrate is not restricted and can be applied to any portion of the substrate, and process color ink (having no infrared absorption or Even when an information pattern is formed on an image portion formed by a low ink), the quality of the image is not impaired. In particular, the use of an ink whose information pattern and base material are difficult to distinguish in terms of color can further improve the image quality.

  An image by process ink is not necessarily required, but a predetermined image capable of transmitting infrared rays by using at least one chromatic or achromatic color ink, particularly at least three color process inks, on the substrate surface on which the information pattern is formed. Is often formed. The ink for forming this image is not particularly limited, printing ink such as lithographic ink, letterpress ink, gravure ink, flexo ink, screen ink, ink for inkjet, thermal transfer ink, toner for developing electrostatic image, etc. It may be.

  Further, chromatic or three-color process inks are colorants that can transmit infrared rays, such as yellow pigments such as disazo yellow and condensed azo, lake red C, brilliant carmine 6B, rhodamine 6G, rhodamine B, and watching red. A red pigment, a blue pigment such as phthalocyanine blue, and a green pigment such as phthalocyanine green may be included. The achromatic or black ink colorant uses a subtractive color mixture, and a plurality of colorants that can transmit infrared rays, for example, a combination of yellow, red, and blue pigments, a combination of an orange pigment and a blue pigment, A black colorant prepared by a combination of a green pigment and a red pigment, a combination of a yellow pigment and a purple pigment, or the like is preferable.

  The substrate is not particularly limited as long as it has an infrared reflective surface, and is a paper substrate such as printing paper, gravure paper, fine paper, coated paper, baryta paper, art paper, cast coated paper, synthetic paper, polyolefin resin, etc. It may be a plastic substrate (or plastic sheet) composed of styrene resin, polyester resin, polyamide resin, etc., and a laminate in which a plurality of layers are laminated (for example, paper is laminated on a plastic sheet) A laminated body, a vapor deposition film, etc.). Moreover, the base material may be colored as long as it has infrared reflectivity. As the substrate, a paper substrate such as white coated paper, particularly a white paper substrate is often used. The infrared reflectance of the substrate is, for example, 50 to 100%, preferably 60 to 100%, more preferably 70 to 100% with respect to the infrared rays to be irradiated (for example, infrared rays having a wavelength of 850 to 950 nm).

  The ink composition of the present invention includes identification documents such as passports, driver's licenses, employee ID cards, stock certificates, bonds, checks, passbooks, lottery tickets, coupon tickets, commuter passes, tickets and other securities, ID cards, credit cards, This is effective in preventing unauthorized use of counterfeit cards such as cash cards, gift cards, and prepaid cards. Furthermore, by applying the information pattern to various printed materials, it is useful to reproduce information corresponding to the information pattern as visible, audible, and readable information such as voice, image, character, and symbol.

  EXAMPLES The present invention will be described in more detail with reference to the following examples. However, the following examples do not limit the scope of rights of the present invention. Unless otherwise specified, “part” in Examples represents “part by weight” and “%” represents “% by weight”.

(Example of production of rosin-modified phenolic resin)
[Production Example 1] (Rosin-modified phenolic resin A, for lithographic ink)
To a four-necked flask equipped with a stirrer, a cooler, and a thermometer, 1000 parts of P-octylphenol, 850 parts of 35% formalin, 60 parts of 93% sodium hydroxide and 1000 parts of toluene were added, and the mixture was heated at 80-90 ° C. for 6 hours. Reacted. Thereafter, 125 parts of 6N hydrochloric acid and 1000 parts of tap water were added, and the mixture was stirred and allowed to stand. The upper layer was taken out to obtain 2000 parts of a toluene solution of a resole-type phenol resin having a nonvolatile content of 49%. A.

  A four-necked flask equipped with a stirrer, a condenser with a water separator, and a thermometer was charged with 1000 parts of gum rosin, dissolved at 200 ° C. while blowing nitrogen gas, and 1800 parts of the resole liquid A produced above was added. After reacting at 230 ° C. for 4 hours while removing toluene, 110 parts of glycerin was added and reacted at 250 ° C. for 10 hours to obtain an oxidation of 20 or less, a weight average molecular weight of 40000, Shin Nippon Petrochemical Co., Ltd. AF Solvent No. 6 The rosin-modified phenol resin A for lithographic ink having a white turbidity temperature of 80 ° C. and a resin viscosity of 10.0 Pa · s was obtained.

[Production Example 2] (Rosin-modified phenolic resin B, for waterless lithographic ink)
To a four-necked flask equipped with a stirrer, a cooler, and a thermometer, 720 parts of P-octylphenol, 375 parts of P-dodecylphenol, 290 parts of paraformaldehyde, 60 parts of 93% sodium hydroxide, and 800 parts of xylene were added. The reaction was carried out at -90 ° C for 5 hours. Thereafter, 125 parts of 6N hydrochloric acid and 200 parts of tap water were added, stirred and allowed to stand, and the upper layer part was taken out to obtain 2000 parts of a xylene solution of a resole-type phenol resin having a nonvolatile content of 63%. B.

  A four-necked flask equipped with a stirrer, a condenser with a water separator and a thermometer was charged with 600 parts of gum rosin, dissolved at 200 ° C. while blowing nitrogen gas, and 770 parts of the resole solution B produced above was added. After reacting at 220 ° C. for 4 hours while removing toluene, charge 67 parts of glycerin and react at 250 ° C. for 12 hours to obtain an oxidation of 18 or less, a weight average molecular weight of 200,000, Shin Nippon Petrochemical Co., Ltd. AF Solvent No. 6 The rosin-modified phenol resin B for waterless lithographic ink having a cloudiness temperature of 100 ° C. and a resin viscosity of 23.0 Pa · s was obtained.

(Example of varnish production)
[Production Example 3] (Varnish Production Example 1 for lithographic ink)
42 parts of rosin-modified phenolic resin A, 33 parts of soybean oil, 24 parts of AF solvent 6 (solvent manufactured by Shin Nippon Petrochemical Co., Ltd.), 1.0 part of ALCH (gelator manufactured by Kawaken Fine Chemicals Co., Ltd.) The mixture was heated and stirred at 190 ° C. for 1 hour to obtain a lithographic ink varnish A.

[Production Example 4] (Varnish Production Example 2 for waterless lithographic ink)
42 parts of rosin-modified phenolic resin A, 28 parts of soybean oil, 5 parts of soybean fatty acid isobutyl ester (manufactured by Toei Chemical Co., Ltd.), 10 parts of dialen 168 (Mitsubishi Chemical Corporation, 1-hexadecene, 1-octadecene mixture) , AF Solvent No. 6 (Shin Nippon Petrochemical Co., Ltd. solvent) 14 parts, ALCH (Kawaken Fine Chemical Co., Ltd. gelling agent), 1.0 part heated and stirred at 190 ° C for 1 hour, no water Varnish B for lithographic ink was obtained.

[Production Example 5] (Varnish Production Example 3, for UV curable lithographic ink)
25 parts of Dap Tote DT170 (manufactured by Toto Kasei Co., Ltd.) is added to 75 parts of DPHA (manufactured by Nippon Kayaku Co., Ltd.) heated to 90 ° C.-100 ° C., and heated and stirred at 90 ° C.-100 ° C. for 1 hour. A varnish C for curable lithographic ink was obtained.

[Production Example 6] (Varnish Production Example 4, UV-curable waterless lithographic ink)
32 parts of Dap Tote DT170 (manufactured by Tohto Kasei Co., Ltd.) is added to 68 parts of DPHA (manufactured by Nippon Kayaku Co., Ltd.) heated to 90 ° C-100 ° C, and heated and stirred at 90 ° C-100 ° C for 1 hour, ultraviolet rays A curable varnish D for waterless lithographic ink was obtained.

The cloudiness temperature was measured with a 10% diluted state of AF Solvent 6 manufactured by Nippon Petrochemical Co., Ltd., using NOVOCONTROL manufactured by CHEMOTRONIC. The resin viscosity is a viscosity value at 25 ° C. measured by a varnish cone plate viscometer obtained by heating and stirring a mixture having a weight ratio of resin / linseed oil = 1/2 at 180-200 ° C.
(Near infrared absorption base ink production example)

[Production Example 7] (Near-infrared absorption base ink production example 1, for lithographic ink)
Varnish A 33.5 parts, Shiraka Hana O (calcium carbonate manufactured by Shiraishi Kogyo Co., Ltd.) 20 parts, eXcolor IR-12 (Nippon Shokubai Co., Ltd. near infrared absorber) 2 parts, AF Solvent No. 6 8.2 parts Was milled with a three-roll mill and a temperature condition of 60 ° C. with a dispersed particle size measuring device (grind meter) until the particle size became 7.5 μm or less to obtain a near infrared absorption base ink A for lithographic ink. .

[Production Example 8] (Near-infrared absorption base ink production example 2, for waterless lithographic ink)
Varnish B 33.5 parts, Shiraka Hana O (calcium carbonate manufactured by Shiraishi Kogyo Co., Ltd.) 20 parts, eXcolor IR-12 (Nippon Shokubai Co., Ltd. near infrared absorber) 2 parts, AF Solvent No. 6 8.2 parts Is milled with a three-roll mill at a temperature condition of 60 ° C. with a dispersed particle size measuring device (grind meter) until the particle size becomes 7.5 microns or less, and the near-infrared absorption base ink B for waterless lithographic ink is obtained. Obtained.

[Production Example 9] (Near-infrared absorption base ink production example 3, for ultraviolet curable lithographic ink)
Varnish C 35.5 parts, Shiraka Hana O (calcium carbonate manufactured by Shiraishi Kogyo Co., Ltd.) 20 parts, eXcolor IR-12 (Nippon Shokubai Co., Ltd. near infrared absorber) 2 parts, Aronix M-408 6.2 parts Is milled with a three roll mill at a temperature condition of 60 ° C. with a dispersed particle size measuring device (grind meter) until the particle size becomes 7.5 microns or less, and the near-infrared absorbing base ink C for ultraviolet curable lithographic ink Got.

[Production Example 10] (Near-infrared absorption base ink production example 4, UV-curable waterless lithographic ink)
Varnish D32.5 parts, Shiraka Hana O (calcium carbonate manufactured by Shiraishi Kogyo Co., Ltd.) 20 parts, eXcolor IR-12 (Nippon Shokubai Co., Ltd. near infrared absorber) 2 parts, Aronix M-408 9.2 parts Is milled with a three-roll mill at a temperature of 60 ° C. with a dispersed particle size meter (grind meter) until the particle size becomes 7.5 microns or less, and a near infrared absorption base for UV-curable waterless lithographic ink Ink D was obtained.
Example of optical brightener base ink production Yubitex OB manufactured by Ciba Specialty Chemicals was used as the optical brightener according to the present invention.

[Production Example 11] (Fluorescent brightener base ink production example 1, for lithographic ink)
According to the composition shown in Table 1, the mixture is kneaded with a three-roll, temperature condition of 30 ° C. with a dispersed particle size measuring device (grind meter) until the particle size becomes 7.5 microns or less. Ink A was obtained.

[Production Example 12] (Fluorescent brightener base ink production example 2, for waterless ink)
According to the composition shown in Table 1, the mixture is kneaded with a three-roll, temperature condition of 30 ° C. with a dispersed particle size measuring device (grind meter) until the particle size becomes 7.5 microns or less, and fluorescent whitening for waterless lithographic ink Agent base ink B was obtained.

[Production Example 13] (Fluorescent brightener-based ink production example 3, for ultraviolet curable lithographic ink)
According to the composition shown in Table 1, it is kneaded with a three-roll, temperature condition of 30 ° C. with a dispersed particle size measuring device (grind meter) until the particle size becomes 7.5 microns or less, and the fluorescence increase for ultraviolet curable lithographic inks. White agent base ink C was obtained.

[Production Example 14] (Fluorescent brightener base ink production example 4, UV-curable waterless lithographic ink)
According to the composition shown in Table 1, three rolls and temperature conditions of 30 ° C. are kneaded with a dispersed particle size meter (grind meter) until the particle size is 7.5 microns or less, and used for UV-curable waterless lithographic ink An optical brightener base ink D was obtained.

[Example 1] Lithographic ink According to the composition shown in Table 2, a near-infrared absorbing base ink A and a fluorescent brightener base ink A were applied to a varnish A, a metal dryer, and AF solvent 6 at a temperature of 30 ° C in three rolls. No., a friction-resistant compound, and a drying inhibitor were used for dilution adjustment to obtain a lithographic printing ink NIRFL-1 with a viscosity of 60.0 Pa · s.

[Example 2] Waterless lithographic ink In accordance with the composition shown in Table 2, near-infrared absorbing base ink B and fluorescent brightener base ink B at three rolls and temperature conditions of 30 ° C., varnish B, metal dryer, AF Dilution adjustment was performed with Solvent No. 6, a friction-resistant compound, and a drying inhibitor, and a near-infrared absorbing waterless lithographic printing ink NIRFL-2 was obtained with a viscosity of 90.0 Pa · s.

[Example 3] Ultraviolet curable lithographic ink According to the composition shown in Table 2, three-roll, temperature condition 30 ° C, near-infrared absorbing base ink C, fluorescent brightener base ink C, varnish C, Irgacure 907, Dilution adjustment was performed with Aronix M-408, a friction-resistant compound, and a polymerization inhibitor, and a near-infrared absorbing ultraviolet curable lithographic printing ink NIRFL-3 was obtained with a viscosity of 60.0 Pa · s.

[Example 4] UV-curable waterless lithographic ink In accordance with the composition shown in Table 2, near-infrared absorbing base ink D and fluorescent brightener base ink D, varnish D and Irgacure at 3 rolls and temperature condition of 30 ° C. 907, Aronix M-408, anti-friction compound, and polymerization inhibitor were used for dilution adjustment to obtain a near-infrared absorbing UV-curable waterless lithographic printing ink NIRFL-4 with a viscosity of 90.0 Pa · s.

[Comparative Example 1] Lithographic ink In accordance with the formulation shown in Table 2, the near-infrared absorbing base ink A is prepared with varnish A, metal dryer, AF Solvent No. 6, compound, and drying inhibitor at three rolls and at a temperature of 30 ° C. Dilution adjustment was performed to obtain a lithographic printing medium ink M-1 with a viscosity of 60.0 Pa · s.

[Comparative Example 2] Waterless lithographic ink In accordance with the composition shown in Table 2, the near-infrared absorbing base ink B is varnish B, metal dryer, AF Solvent No. 6, compound, drying suppression, at 3 rolls and at a temperature of 30 ° C. Dilution adjustment was performed with an agent to obtain waterless lithographic printing medium ink M-2 with a viscosity of 90.0 Pa · s.

[Comparative Example 3] UV curable lithographic ink In accordance with the composition shown in Table 2, the near-infrared absorbing base ink C, varnish C, Irgacure 907, Aronix M-408, compound, polymerization, at 3 rolls and temperature condition of 30 ° C Dilution adjustment was performed with an inhibitor to obtain UV-curable lithographic printing medium ink M-3 with a viscosity of 60.0 Pa · s.

[Comparative Example 4] UV-curable waterless lithographic ink According to the composition shown in Table 2, near-infrared absorbing base ink D was applied to varnish D, Irgacure 907, Aronix M-408, compound at 3 rolls and temperature condition of 30 ° C. Then, the dilution was adjusted with a polymerization inhibitor to obtain UV-curable waterless lithographic printing medium ink M-4 with a viscosity of 90.0 Pa · s.

  The inks obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were printed using an offset sheet-fed printing press to obtain proof-print samples. The print sample creation conditions are described below.

[Lithographic ink printing conditions]
Printing machine: Lithrone 426 (manufactured by Komori Corporation, sheet-fed chrysanthemum half-color 4-color machine)
Version: CTP version for flat plate HP-F (Fuji Film Graphic Systems Co., Ltd.)
Dampening solution: AQUAUNITY SNP 2.0% (manufactured by Toyo Ink Manufacturing Co., Ltd.)
Paper: Tokuhishi Art Double Side N 79.5kg Y Eye (Mitsubishi Paper Co., Ltd.)
Printing speed: 8000 sheets / hour

[Waterless planographic ink printing conditions]
Printing machine: Lithrone 426 (manufactured by Komori Corporation, sheet-fed chrysanthemum half-color 4-color machine)
Version: CTP version VG5 for waterless flat plate (Toray Industries, Inc.)
Paper: Tokuhishi Art Double Side N 79.5kg Y Eye (Mitsubishi Paper Co., Ltd.)
Printing speed: 8000 sheets / hour

[Verification of visibility]
In order to confirm the effect of the fluorescent whitening agent according to the present invention, in order to evaluate the visibility of halftone dots at each halftone dot area ratio of a proof print sample printed using an offset sheet-fed printing press, the print samples were evaluated according to JIS. Observation was performed in a booth with artificial daylight D50 illumination defined by Z 8723, and it was confirmed whether or not the hue difference between the blank paper portion and the printed portion could be identified. Evaluation was carried out according to the following criteria.
The hue difference cannot be confirmed visually. : ○
Although the hue difference is slight, it can be confirmed visually: △
The hue difference can be clearly confirmed visually. : ×

[Spectral reflectance measurement]
In order to evaluate the sensitivity of the near-infrared absorbing material used in the present invention to the infrared sensor, the spectral reflectance curve (UV3600, manufactured by Shimadzu Corporation) of the printed sample was measured. The measurement conditions are described below.
Measuring device: UV3600 (Shimadzu Corporation ultraviolet visible near infrared spectrophotometer)
Wavelength range: 350.00-1000.00nm
Sampling pitch: 0.50 nm
Scanning speed: High speed Photometric value: Reflectance Slit width: 20 nm
Detector: Integral sphere Base line: Tokuhishi art double side N 79.5kg Y eyes (Mitsubishi Paper Co., Ltd.)
Measurement location: 100% solid part of print sample

In addition, regarding the evaluation of sensitivity to the infrared sensor, the following judgment criteria are used by using the reflectance at the absorption maximum wavelength of 898 nm of the inks of Examples 1-4 and Comparative Example 1-4 including the near-infrared absorber eXcolor IR-12. Judged by.
40% to 100%: poor sensitivity 0% to 40%: good sensitivity

[Image shooting with infrared reader]
Using a microscope (MX-61IR manufactured by Olympus Co., Ltd.) equipped with a transmissive filter in the wavelength region of 850 nm to 950 nm, an image of the printed sample (halftone dot = 20%) was taken.

  As shown in Table 3, the ink composition of Example 1-4 containing a fluorescent brightening agent was improved in invisibility by the halftone dot area ratio (%) at the time of printing, and clearly with the white paper base material. Hue difference is no longer confirmed. In addition, by adding a fluorescent brightening agent, the spectral reflectance in the near-infrared region (absorption maximum wavelength: 898 nm) is as good as 36%, and the halftone dot shape is clearly observed by a microscope equipped with an infrared transmission filter. I was able to confirm. On the other hand, the ink composition of Comparative Example 1-4 shown in Table 4 was confirmed to be colored when printed at each halftone dot area ratio (%), resulting in poor visibility.

  The printed matter using the lithographic ink composition obtained by adding the fluorescent brightener according to the present invention has improved invisibility, and a near-infrared absorbing ink composition with improved stealth can be obtained.

Claims (9)

  At least one or more near-infrared absorbers having an excitation wavelength of 300 nm to 400 nm, containing at least one or more fluorescent whitening agents having an emission wavelength of 400 nm to 550 nm, and having a spectral absorption maximum wavelength of 750 nm to 1100 nm A lithographic ink composition containing two or more.   A lithographic ink composition comprising 0.01 to 20% by weight of the optical brightener according to claim 1 and 0.1 to 20% by weight of a near infrared absorber. .   A lithographic ink composition, wherein the lithographic ink composition according to claim 1 is an offset printing ink with water.   A lithographic ink composition, wherein the lithographic ink composition according to claim 1 is a waterless offset printing ink.   5. The lithographic ink composition according to claim 1, wherein the lithographic ink composition is an oxidation polymerization type ink.   The lithographic ink composition according to claim 1, wherein the lithographic ink composition is an actinic ray curable ink.   A substrate having an infrared reflective surface, and an information pattern formed of the lithographic ink according to claims 1 to 6 on the surface of the substrate and composed of fine elements that are difficult to recognize visually, An optically readable information carrying sheet.   The information carrying sheet according to claim 7, wherein the information pattern is composed of fine dot-like elements. The information carrying sheet according to claim 7 or 8, wherein the information pattern is composed of dots having an average diameter of 1 to 100 µm and a thickness of 0.5 to 2 µm.