Composition for forgery prevention ink and printed matter for forgery prevention

Abstract

The purpose of the present invention is to provide a composition for anti-counterfeiting ink, which contains organic-inorganic mixed infrared absorbing particles and a liquid medium, the organic-inorganic mixed infrared absorbing particles comprise 15-55 mass% of infrared absorbing particles and a coating resin that covers at least a part of the surfaces of the infrared absorbing particles.

Description

Technical Field

[0001] The present invention relates to a composition for anti-counterfeiting ink and an anti-counterfeiting printed matter. Background Art

[0002] Heretofore, methods for preventing counterfeiting have been studied for valuable printed matters such as deposit and withdrawal passbooks, identification certificates, credit cards, cash cards, checks, airline tickets, road passes, train tickets, prepaid cards, gift certificates, securities, etc. Further, as a method for preventing counterfeiting of valuable printed matters, special processes have been applied to their base materials and printing methods.

[0003] For example, in order to prevent counterfeiting, latent image printing (see Patent Document 1), digital processing printing using geometric shapes typified by barcodes, etc. are performed. However, barcode printing can be easily counterfeited by copying or the like. In addition, latent image printing increases ambiguous elements such as confirmation by the human eye, etc., and thus the anti-counterfeiting effect is low and not versatile.

[0004] As an anti-counterfeiting method other than the above, a method has been proposed in which printing ink that absorbs little in the visible light region of wavelengths 300 to 780 nm and absorbs near-infrared rays of wavelengths 800 to 2400 nm is used to detect the authenticity information of a printed matter. For example, when printing with an ink containing a near-infrared absorbing material that absorbs little in the visible light region and an adhesive resin, if an infrared laser is irradiated onto the printed surface, only a specific wavelength is absorbed, and thus by reading the reflected or transmitted light, the authenticity can be determined.

[0005] As such a near-infrared absorbing printing ink, a security ink using a phthalocyanine compound has been proposed (see Patent Document 2). However, the phthalocyanine compound as a near-infrared absorbing material has a disadvantage in that its absorption characteristics deteriorate due to the influence of temperature, ultraviolet rays, etc., and thus its weather resistance is poor.

[0006] On the other hand, a dispersion film containing 6-boride fine particles such as Y and La, ruthenium oxide fine particles, etc. is known as a solar ray absorbing near-infrared and heat insulating solar radiation absorbing film, and a concept of applying it to anti-counterfeiting ink has been proposed (see Patent Document 3). However, when applying this solar radiation absorbing film to anti-counterfeiting ink, sometimes the contrast of light absorption with respect to light transmission or reflection in the wavelength region of transmitted or reflected light and the wavelength region of absorbed light is insufficient during coating. Therefore, sometimes depending on the use, the reading accuracy, etc. when used as anti-counterfeiting ink deteriorates.

[0007] The present applicant has disclosed an anti-counterfeiting ink containing composite tungsten oxide fine particles (see Patent Document 4) that has a high contrast of absorption in the near-infrared region relative to transmission or reflection in the visible region and excellent weather resistance. However, according to the research of the inventors of the present invention, it has been clarified that the chemical resistance of the infrared absorption particles described in Patent Document 4 is insufficient. Therefore, if the anti-counterfeiting ink or the printed matter for anti-counterfeiting is exposed to a chemical environment such as high-temperature acid or alkali, the infrared absorption characteristics will decrease.

[0008] Therefore, the present applicant has disclosed a composition for anti-counterfeiting ink, an anti-counterfeiting ink, and a printed matter for anti-counterfeiting that have excellent chemical resistance (see Patent Document 5). According to the research of the inventors of the present invention, it has been clarified that the chemical resistance of the infrared absorption particles described in Patent Document 5 is sufficient, but there is room for improvement in the infrared absorption characteristics.

[0009] Prior Art Documents

[0010] Patent Documents

[0011] Patent Document 1: Japanese Patent Laid-Open No. 05-338388

[0012] Patent Document 2: Japanese Patent Laid-Open No. 04-320466

[0013] Patent Document 3: Japanese Patent Laid-Open No. 2004-168842

[0014] Patent Document 4: Japanese Patent Laid-Open No. 2015-117353

[0015] Patent Document 5: Japanese Patent Laid-Open No. 2020-196850 Summary of the Invention

[0016] Problems to be Solved by the Invention

[0017] The present invention focuses on such problems, and an object of one aspect of the present invention is to provide a composition for anti-counterfeiting ink having excellent infrared absorption characteristics and chemical resistance.

[0018] Means for Solving the Problems

[0019] One aspect of the present invention provides a composition for anti-counterfeiting ink, which contains organic-inorganic hybrid infrared absorption particles and a liquid medium.

[0020] The above-mentioned organic-inorganic hybrid infrared absorption particles have infrared absorption particles of 15% by mass or more and 55% by mass or less, and a coating resin that covers at least a part of the surface of the infrared absorption particles.

[0021] Effects of the Invention

[0022] One aspect of the present invention can provide a composition for anti-counterfeiting ink having excellent infrared absorption characteristics and chemical resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is an explanatory diagram of the hexagonal crystal structure of a composite tungsten oxide.

[0024] Figure 2 It is a cross-sectional schematic view of the organic-inorganic hybrid infrared absorption particles of the present embodiment.

[0025] Figure 3 It is a schematic diagram of the composition for anti-counterfeiting ink of the present embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Hereinafter, the present specific embodiment will be described with reference to the drawings. The present invention is not limited to the following embodiments, and various modifications and substitutions can be made to the following embodiments without departing from the scope of the present invention.

[0027] [Composition for anti-counterfeiting ink]

[0028] The composition for anti-counterfeiting ink of the present embodiment can contain organic-inorganic hybrid infrared absorption particles and a liquid medium.

[0029] The organic-inorganic hybrid infrared absorption particles can have infrared absorption particles and a coating resin that covers at least a part of the surface of the infrared absorption particles. The organic-inorganic hybrid infrared absorption particles can make the content ratio of the infrared absorption particles be 15% by mass or more and 55% by mass or less.

[0030] As described above, infrared absorption particles are used for anti-counterfeiting ink and the like, but sometimes the chemical resistance is insufficient.

[0031] Therefore, the inventors of the present invention have conducted in-depth research on a method for producing infrared absorption particles having excellent infrared absorption characteristics and chemical resistance.

[0032] As a result, it was found that an organic material such as resin was directly disposed on at least a part of the surface of the infrared absorption particles to form organic-inorganic hybrid infrared absorption particles. Further, it was found that organic-inorganic hybrid infrared absorption particles having a content ratio of infrared absorption particles of 15% by mass or more and 55% by mass or less, which were particularly difficult to produce in the past, have both excellent infrared absorption characteristics and chemical resistance. Moreover, it was found that by using such organic-inorganic hybrid infrared absorption particles, a composition for anti-counterfeiting ink and an anti-counterfeiting printed matter having excellent infrared absorption characteristics and chemical resistance were produced, and the present invention was completed.

[0033] Infrared absorption particles are usually inorganic materials, and it is difficult to dispose an organic material such as resin on at least a part of their surfaces. Therefore, organic-inorganic hybrid infrared absorption particles and a method for manufacturing the same are unknown. In particular, as described above, a method for manufacturing organic-inorganic hybrid infrared absorption particles having a high content ratio of infrared absorption particles is unknown. Therefore, the inventors of the present invention conducted research and found an organic-inorganic hybrid infrared absorption particle having a high content ratio of infrared absorption particles in which an organic material is disposed on at least a part of the surface of the infrared absorption particle, and a method for manufacturing the same.

[0034] Therefore, first, a method for manufacturing organic-inorganic hybrid infrared absorption particles and the organic-inorganic hybrid infrared absorption particles will be described.

[0035] 1. Method for manufacturing organic-inorganic hybrid infrared absorption particles

[0036] The method for manufacturing organic-inorganic hybrid infrared absorption particles can include, for example, the following dispersion liquid preparation step, dispersion medium reduction step, raw material mixture preparation step, stirring step, and polymerization step.

[0037] In the dispersion liquid preparation step, a dispersion liquid containing infrared absorption particles, a dispersant, and a dispersion medium can be prepared.

[0038] In the dispersion medium reduction step, the dispersion medium can be evaporated from the dispersion liquid.

[0039] In the raw material mixture preparation step, the infrared absorption particles recovered after the dispersion medium reduction step, a resin raw material for coating, an organic solvent, an emulsifier, water, and a polymerization initiator can be mixed to prepare a raw material mixture.

[0040] In the stirring step, the raw material mixture can be stirred while being cooled.

[0041] In the polymerization step, after performing a deoxidation treatment to reduce the amount of oxygen in the raw material mixture, a polymerization reaction of the resin raw material for coating can be performed.

[0042] Hereinafter, each step will be described.

[0043] (1) Dispersion liquid preparation step

[0044] In the dispersion liquid preparation step, a dispersion liquid containing infrared absorption particles, a dispersant, and a dispersion medium can be prepared.

[0045] Each material that can be suitably used when preparing the dispersion liquid in the dispersion liquid preparation step will be described.

[0046] (a) Infrared absorption particles (regarding composition, etc.)

[0047] In the dispersion preparation step, as the infrared absorbing particles, various infrared absorbing particles that require improved chemical resistance, such as acid resistance and alkali resistance, can be used. As the infrared absorbing particles, for example, infrared absorbing particles containing various materials with free electrons are preferably used, and more preferably, infrared absorbing particles containing various inorganic materials with free electrons can be used.

[0048] As the infrared absorbing particles, infrared absorbing particles containing one or more selected from tungsten oxides with oxygen deficiency and composite tungsten oxides are particularly preferably used. In this case, specifically, the infrared absorbing particles preferably contain, for example, tungsten oxides represented by the general formula W y O z (W: tungsten, O: oxygen, 2.2 ≤ z / y ≤ 2.999) and composite tungsten oxides represented by the general formula M x W y O z (Element M is one or more selected from H, He, Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Hf, Os, Bi, I, 0.001 ≤ x / y ≤ 1, 2.0 ≤ z / y < 4.0).

[0049] Generally, it is known that materials containing free electrons show reflection absorption response to electromagnetic waves in the region of solar light with wavelengths of 200 nm to 2600 nm through plasma vibration. Therefore, various materials containing free electrons can be suitably used as infrared absorbing particles. For example, if the infrared absorbing particles become particles smaller than the wavelength of light, geometric scattering in the visible light region (wavelength 380 nm to 780 nm) can be reduced, and particularly high transparency can be obtained for the visible light region, so it is preferred.

[0050] In addition, in this specification, "transparency" is used in the sense of "less scattering and high transmittance for light in the visible light region."

[0051] Generally, there are no effective free electrons in tungsten oxide (WO 3 ), so the absorption and reflection characteristics in the infrared region are small, and it is not effective as infrared absorbing particles.

[0052] On the other hand, it is known that WO with oxygen deficiency3 、WO 3 The composite tungsten oxide added with positive elements such as Na is a conductive material and a material with free electrons. Moreover, it is implied that the response of free electrons to light in the infrared region is analyzed through single crystals of these materials with free electrons, etc.

[0053] According to the research of the inventors of the present invention, etc., in a specific part of the composition range of tungsten and oxygen, it has a particularly effective range as an infrared absorption material. Moreover, by making the composition of tungsten and oxygen within a particularly effective specific range as an infrared absorption material, tungsten oxides and composite tungsten oxides that are transparent in the visible light region and have particularly strong absorption in the infrared region can be produced.

[0054] Therefore, tungsten oxides and composite tungsten oxides, which are a kind of materials for infrared absorption particles that can be suitably used in the dispersion liquid preparation process, are further described below.

[0055] (a1) Tungsten oxide

[0056] Tungsten oxide is represented by the general formula W y O z (wherein, W is tungsten, O is oxygen, and 2.2 ≤ z / y ≤ 2.999).

[0057] In the tungsten oxide represented by the general formula W y O z In the tungsten oxide represented by the formula, the composition range of tungsten and oxygen, that is, the composition ratio of oxygen to tungsten (z / y) is preferably less than 3, more preferably 2.2 ≤ z / y ≤ 2.999. In particular, it is further preferably 2.45 ≤ z / y ≤ 2.999.

[0058] If the value of z / y is 2.2 or more, the appearance of the crystal phase of WO 2 which is not the target in the tungsten oxide can be avoided, and the chemical stability of the material can be obtained, so it becomes a particularly effective infrared absorption particle.

[0059] In addition, by making the value of z / y preferably less than 3, more preferably 2.999 or less, the absorption and reflection characteristics in the infrared region are improved. Therefore, in particular, a sufficient amount of free electrons are generated, and infrared absorption particles can be efficiently produced.

[0060] In addition, the so-called "magnetite phase" having a composition ratio of 2.45 ≤ z / y ≤ 2.999 is chemically stable and has excellent absorption characteristics for light in the near-infrared region. Therefore, it is more preferably used as an infrared absorption material. Therefore, as described above, z / y is further preferably 2.45 ≤ z / y ≤ 2.999.

[0061] (a2) Composite tungsten oxide

[0062] The composite tungsten oxide is a product obtained by adding the following element M to the above WO 3 and adding the following element M.

[0063] By adding element M, a composite tungsten oxide is prepared, thereby generating free electrons in WO 3 and exhibiting strong absorption characteristics of free electron sources, particularly in the near-infrared region, and becoming effective as infrared absorbing particles that absorb near-infrared rays with a wavelength of around 1000 nm.

[0064] That is, by preparing a composite tungsten oxide with controlled oxygen consumption and addition of element M that generates free electrons for this WO 3 , the infrared absorption characteristics can be more efficiently exhibited. When the general formula of the composite tungsten oxide with controlled oxygen consumption and addition of element M that generates free electrons for WO 3 is denoted as M x W y O z it is preferably satisfied that 0.001 ≤ x / y ≤ 1 and 2.0 ≤ z / y < 4.0. In the above general formula, M represents the aforementioned element M, W represents tungsten, and O represents oxygen.

[0065] As described above, when the value of x / y representing the addition amount of element M is 0.001 or more, in the composite tungsten oxide, a sufficient amount of free electrons can be particularly generated, and a high infrared absorption effect can be obtained. Moreover, the more the addition amount of element M, the increase in the supply amount of free electrons and the rise in the infrared absorption efficiency, but the effect also saturates when the value of x / y is around 1. In addition, when the value of x / y is 1 or less, the generation of impurity phases in the infrared absorbing particles containing the composite tungsten oxide can be avoided, so it is preferred.

[0066] In addition, element M is preferably at least one selected from H, He, Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Hf, Os, Bi, I.

[0067] Especially for improving M x W y O zFrom the perspective of stability, element M is more preferably at least one element selected from Li, Na, K, Rb, Cs, Fr, Mg, Ca, Sr, Ba, Ra, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re. Further, from the perspective of improving the optical properties and weather resistance of the infrared absorption particles containing the composite tungsten oxide, element M is further preferably at least one element selected from alkaline earth metal elements, transition metal elements, Group 4B elements, and Group 5B elements.

[0068] Regarding the value of z / y representing the amount of oxygen added, in the composite tungsten oxide represented by M x W y O z the same mechanism as in the tungsten oxide represented by the above W y O z works. However, in the composite tungsten oxide, further, when z / y = 3.0 and the amount of oxygen added exceeds 3.0 and is excessive, there is a supply of free electrons due to the added amount of the above element M. Therefore, it is preferably 2.0 ≤ z / y < 4.0, more preferably 2.2 ≤ z / y ≤ 3.8, and further preferably 2.45 ≤ z / y < 3.6.

[0069] Further, when the composite tungsten oxide has a hexagonal crystal structure, the transmittance of light in the visible light region of the infrared absorption particles containing the composite tungsten oxide is improved, and the absorption of light in the infrared region is improved. While referring to the schematic plane of the hexagonal crystal structure Figure 1 it will be described.

[0070] Figure 1 shows a projection view when observing the crystal structure of the composite tungsten oxide having a hexagonal crystal structure from the (001) direction, and the unit lattice 10 is represented by a dotted line.

[0071] Figure 1 In, 116 octahedrons formed by WO 6 units are assembled to form a hexagonal void 12. In this void 12, element 121 as element M is arranged to form one unit, and multiple sets of this one unit form a hexagonal crystal structure.

[0072] Moreover, in order to improve the transmittance of light in the visible light region and the absorption of light in the infrared region, as long as in the composite tungsten oxide, it contains the use ofFigure 1 The unit structure for description is sufficient. Therefore, the composite tungsten oxide can be crystalline or amorphous.

[0073] When a cation of element M is added and present in the voids of the above hexagon, the transmittance of light in the visible region is improved, and the absorption of light in the infrared region is improved. Generally speaking here, when an element M with a large ionic radius is added, it is easy to form this hexagonal crystal. Specifically, when one or more elements selected from Cs, K, Rb, Tl, In, Ba, Li, Ca, Sr, Fe, Sn are added as element M, it is easy to form a hexagonal crystal. Of course, even for elements other than these, as long as the above element M exists in the voids of the hexagon formed by WO 6 units, it is not limited to the above elements.

[0074] The composite tungsten oxide having a crystal structure of a hexagonal crystal has a uniform crystal structure. Therefore, the addition amount of element M is preferably 0.2 or more and 0.5 or less, more preferably 0.33, in terms of the value of x / y in the above general formula. It is considered that when the value of x / y is 0.33, the above element M is arranged in all of the voids of the hexagon.

[0075] In addition, even for those other than hexagonal crystals, the infrared absorbing particles of composite tungsten oxides including tetragonal crystals and cubic crystals also have sufficiently effective infrared absorption characteristics. There is a tendency for the absorption position in the infrared region to change according to the crystal structure, and there is a tendency for the absorption position to shift to the long wavelength side in the order of cubic crystal < tetragonal crystal < hexagonal crystal. In addition, along with this, the absorption of light in the visible region is less in the order of hexagonal crystal, tetragonal crystal, cubic crystal. Therefore, for uses that further transmit the light in the visible region and further shield the light in the infrared region, a composite tungsten oxide of a hexagonal crystal is preferably used. However, the tendency of the optical properties described here is only a general tendency and varies according to the type of added element, the addition amount, and the amount of oxygen, and the present invention is not limited thereto.

[0076] The infrared absorbing particles containing tungsten oxide and composite tungsten oxide greatly absorb the near-infrared region, especially the light around a wavelength of 1000 nm. Therefore, the transmitted color tone often changes from a blue system to a green system.

[0077] (Dispersion particle size)

[0078] The dispersion particle size of the infrared absorbing particles is not particularly limited and can be selected according to its use purpose and the like.

[0079] First, in the case of an application where transparency is to be maintained, the infrared-absorbing particles preferably have a dispersed particle size of 800 nm or less. This is because particles with a dispersed particle size of 800 nm or less do not completely block light due to scattering, can maintain visibility in the visible light region, and can efficiently maintain transparency. Especially when emphasizing transparency in the visible light region, it is preferable to further consider reducing the scattering caused by the particles.

[0080] When emphasizing the reduction of scattering caused by the particles, the dispersed particle size is preferably 200 nm or less, more preferably 100 nm or less. This is because if the dispersed particle size of the particles is small, the scattering of light in the visible light region with a wavelength of 380 nm or more and 780 nm or less due to geometric scattering or Mie scattering is reduced. Moreover, this is because reducing the dispersed particle size of the particles reduces the scattering of light in the above-mentioned visible light region. As a result, for example, an infrared-absorbing film in which infrared-absorbing particles are dispersed becomes a cloudy glass, and it is possible to avoid losing clear transparency. That is, if the dispersed particle size is 200 nm or less, the above-mentioned geometric scattering or Mie scattering is reduced, and it enters the Rayleigh scattering region. This is because in the Rayleigh scattering region, the scattered light decreases in proportion to the 6th power of the particle size. Therefore, as the dispersed particle size decreases, the scattering decreases and the transparency increases.

[0081] Furthermore, if the dispersed particle size is 100 nm or less, the scattered light becomes very little, which is preferable. From the viewpoint of avoiding light scattering, a small dispersed particle size is preferred.

[0082] The lower limit value of the dispersed particle size of the infrared-absorbing particles is not particularly limited. For example, since it can be easily manufactured industrially, the dispersed particle size is preferably 1 nm or more.

[0083] By making the dispersed particle size of the infrared-absorbing particles 800 nm or less, the haze value of the infrared-absorbing particle dispersion in which the infrared-absorbing particles are dispersed in a medium can be 85% or less of the visible light transmittance and 30% or less of the haze. By making the haze 30% or less, it is possible to prevent the infrared-absorbing particle dispersion from becoming a cloudy glass, and in particular, clear transparency can be obtained.

[0084] In addition, the dispersed particle size of the infrared-absorbing particles can be measured using, for example, ELS-8000 manufactured by Otsuka Electronics Co., Ltd. based on the principle of dynamic light scattering method.

[0085] (Microcrystal diameter)

[0086] In addition, from the viewpoint of exhibiting excellent infrared absorption characteristics, the crystallite diameter of the infrared absorption particles is preferably 1 nm or more and 200 nm or less, more preferably 1 nm or more and 100 nm or less, and still more preferably 10 nm or more and 70 nm or less. The measurement of the crystallite diameter can be carried out using the measurement of the X-ray diffraction pattern by the powder X-ray diffraction method (θ-2θ method) and the analysis by the Rietveld method. The measurement of the X-ray diffraction pattern can be carried out using, for example, a powder X-ray diffractometer "X'Pert-PRO / MPD" manufactured by Spectris Co., Ltd.

[0087] (b) Dispersant

[0088] The dispersant is used for the purpose of hydrophobizing the surface of the infrared absorption particles. The dispersant can be selected according to the dispersion system of the combination of the infrared absorption particles, the dispersion medium, the resin raw material for coating, etc. Among them, a dispersant having one or more selected from amino group, hydroxyl group, carboxyl group, sulfonic group, phosphonyl group, and epoxy group as functional groups can be preferably used. When the infrared absorption particles are tungsten oxide or composite tungsten oxide, the dispersant more preferably has an amino group as a functional group.

[0089] The dispersant is more preferably an amine compound having an amino group as a functional group as described above. In addition, the amine compound is further preferably a tertiary amine.

[0090] In addition, since the dispersant is used for the purpose of hydrophobizing the surface of the infrared absorption particles, it is preferably a polymer material. Therefore, the dispersant preferably has, for example, one or more selected from long-chain alkyl groups and benzene rings. Even in the resin raw material for coating, a polymer dispersant having a copolymer of styrene that can be used and 2-(dimethylamino)ethyl methacrylate as a tertiary amine can be more preferably used. The long-chain alkyl group is preferably an alkyl group having 8 or more carbon atoms. In addition, for example, a dispersant that is a polymer material and an amine compound can be used.

[0091] The addition amount of the dispersant is not particularly limited and can be arbitrarily selected. The suitable addition amount of the dispersant can be selected according to the type of the dispersant, the infrared absorption particles, and the specific surface area of the infrared absorption particles. For example, if the addition amount of the dispersant is 10 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the infrared absorption particles, it is particularly easy to prepare a dispersion liquid with a good dispersion state, so it is preferred. The addition amount of the dispersant is more preferably 10 parts by mass or more and 100 parts by mass or less, and still more preferably 20 parts by mass or more and 50 parts by mass or less.

[0092] (c) Dispersion medium

[0093] The dispersion medium only needs to be able to disperse the aforementioned infrared absorbing particles and the dispersant to prepare a dispersion liquid, and various organic compounds can be used, for example.

[0094] As the dispersion medium, one or more selected from aromatic hydrocarbons such as toluene and xylene can be preferably used.

[0095] In the dispersion liquid preparation step, the dispersion liquid can be prepared by mixing the infrared absorbing particles, the dispersant, and the dispersion medium. In order to reduce the dispersion particle size of the infrared absorbing particles and make them uniformly disperse in the dispersion liquid, it is therefore preferable to perform a pulverization treatment on the infrared absorbing particles during mixing.

[0096] There is no particular limitation on the mixing means used when mixing and pulverizing the infrared absorbing particles, the dispersant, and the dispersion medium. For example, one or more selected from a bead mill, a ball mill, a sand mill, a paint shaker, an ultrasonic homogenizer, etc. can be used. In particular, as the mixing means, a bead mill, a ball mill, a sand mill, a paint shaker, etc. using a medium such as beads, balls, and Ottawa sand is more preferably used. This is because, by using a medium agitation mill, the desired dispersion particle size can be achieved for the infrared absorbing particles, especially in a short time, which is preferable from the viewpoints of productivity and suppression of impurity mixing.

[0097] (2) Dispersion medium reduction step

[0098] In the dispersion medium reduction step, the dispersion medium can be evaporated and dried from the dispersion liquid.

[0099] In the dispersion medium reduction step, it is preferable to be able to sufficiently evaporate the dispersion medium from the dispersion liquid to recover the infrared absorbing particles.

[0100] There is no particular limitation on the specific means for evaporating the dispersion medium. For example, a dryer such as an oven, an evaporator, a vacuum fluidized dryer such as a vacuum kneader, a spray dryer such as a spray drying device, etc. can be used.

[0101] In addition, there is no particular limitation on the degree of evaporation of the dispersion medium. For example, it is preferable to be able to obtain a powdery infrared absorbing particle after the dispersion medium reduction step and sufficiently reduce its content ratio.

[0102] By evaporating the dispersion medium, the dispersant can be disposed around the infrared absorbing particles, and infrared absorbing particles with a hydrophobized surface can be obtained. Therefore, the adhesion between such hydrophobized infrared absorbing particles and the coating resin polymerized from the coating resin raw material can be improved, and the coating resin can be disposed on at least a part of the surface of the infrared absorbing particles through the polymerization step described later, etc.

[0103] (3) Raw material mixture preparation step

[0104] In the raw material mixture preparation step, the infrared absorption particles recovered after the dispersion medium reduction step, the resin raw material for coating, the organic solvent, the emulsifier, water, and the polymerization initiator can be mixed to prepare the raw material mixture.

[0105] The infrared absorption particles recovered after the dispersion medium reduction step sometimes have the dispersant supplied in the dispersion liquid preparation step attached to the surface of the particles, becoming infrared absorption particles containing the dispersant. Therefore, in the case where such dispersant-attached infrared absorption particles are present, in the raw material mixture preparation step, such dispersant-containing infrared absorption particles recovered after the dispersion medium reduction step are used as the infrared absorption particles.

[0106] Hereinafter, each material other than the infrared absorption particles used in the raw material mixture preparation step will be described.

[0107] (a) Resin raw material for coating

[0108] The resin raw material for coating polymerizes in the polymerization step described later to become the coating resin disposed on at least a part of the surface of the infrared absorption particles. Therefore, as the resin raw material for coating, various monomers and the like that can form the desired coating resin can be selected by polymerization.

[0109] The coating resin after polymerization is not particularly limited, and can be, for example, one or more resins selected from thermoplastic resins, thermosetting resins, photocurable resins, etc.

[0110] In addition, examples of the thermoplastic resin include polyester resin, polycarbonate resin, acrylic resin, polystyrene resin, polyamide resin, vinyl chloride resin, olefin resin, fluororesin, polyvinyl acetate resin, thermoplastic polyurethane resin, acrylonitrile-butadiene-styrene resin, polyvinyl acetal resin, acrylonitrile-styrene copolymer resin, ethylene-vinyl acetate copolymer resin, etc.

[0111] Examples of the thermosetting resin include phenolic resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, thermosetting polyurethane resin, polyimide resin, silicone resin, etc.

[0112] Examples of the photocurable resin include resins that are cured by irradiation with any one of ultraviolet light, visible light, and infrared light.

[0113] As the resin for coating, it is particularly preferable to contain one or more selected from polyester resin, polycarbonate resin, acrylic resin, polystyrene resin, polyamide resin, vinyl chloride resin, olefin resin, fluororesin, polyvinyl acetate resin, polyurethane resin, acrylonitrile-butadiene-styrene resin, polyvinyl acetal resin, acrylonitrile-styrene copolymer resin, ethylene-vinyl acetate copolymer resin, phenolic resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyimide resin, silicone resin. In addition, as the above-mentioned polyurethane resin, both thermoplastic polyurethane resin and thermosetting polyurethane resin can be used.

[0114] In addition, as the resin for coating, photocurable resin can also be suitably used. As described above, the photocurable resin can contain a resin that cures by irradiation with any of ultraviolet light, visible light, and infrared light.

[0115] Among them, as the resin for coating, a resin that can be applied to the microemulsion polymerization method is preferable. For example, it is more preferable to contain polystyrene resin. In addition, in the case of the micro polystyrene resin as the resin for coating, styrene can be used as the raw material for the resin for coating.

[0116] In addition, as the crosslinking agent, polyfunctional vinyl monomers such as divinylbenzene and ethylene glycol dimethacrylate can also be added.

[0117] (b) Organic solvent

[0118] The organic solvent is not particularly limited, and any non-water-soluble organic solvent can be used without particular limitation. Among them, low-molecular-weight organic solvents are preferable. For example, one or more selected from long-chain alkyl compounds such as hexadecane, alkyl methacrylates with long-chain alkyl moieties such as dodecyl methacrylate and stearyl methacrylate, higher alcohols such as cetyl alcohol, and oils such as olive oil can be cited.

[0119] As the organic solvent, long-chain alkyl compounds are particularly more preferable, and hexadecane is further preferable.

[0120] (c) Emulsifier

[0121] Regarding the emulsifier, that is, the surfactant, any of cationic emulsifiers, anionic emulsifiers, nonionic emulsifiers, etc. can be used without particular limitation.

[0122] As the cationic emulsifier, alkylamine salts, quaternary ammonium salts, etc. can be cited.

[0123] As the anionic emulsifier, acid salts or ester salts, etc. can be cited.

[0124] As nonionic emulsifiers, various esters, various ethers, various ester ethers, alkanolamides, etc. can be cited.

[0125] As the emulsifier, for example, one or more selected from the above materials can be used.

[0126] Among them, from the viewpoint of infrared absorption particles, particularly from the viewpoint of easily forming organic-inorganic hybrid infrared absorption particles, a cationic emulsifier, that is, a surfactant showing cationicity, is preferably used.

[0127] In particular, when an amine compound is used as the dispersant, as the emulsifier, one or more cationic emulsifiers selected from dodecyltrimethylammonium chloride (DTAC), cetyltrimethylammonium chloride (CTAC), etc. are preferably used.

[0128] In addition, when an amine compound is used as the dispersant, if sodium dodecyl sulfate (SDS) which is an anionic emulsifier is used, it is sometimes difficult to form organic-inorganic hybrid infrared absorption particles. When preparing the raw material mixture, the emulsifier can be added, for example, to the water added simultaneously and added as an aqueous solution. At this time, it is preferably adjusted to an aqueous solution at a concentration of 10 times or more and 1000 times or less, more preferably 10 times or more and 500 times or less, further preferably 10 times or more and 300 times or less, and particularly preferably 10 times or more and 150 times or less of the critical micelle concentration (CMC).

[0129] According to the research of the inventors of the present invention, by adding a predetermined proportion of an emulsifier to the added coating resin raw material and sufficiently stirring according to the addition amount of the emulsifier, the content ratio of the infrared absorption particles in the obtained organic-inorganic hybrid infrared absorption particles can be 15% by mass or more. That is, by selecting the addition ratio of the emulsifier to the coating resin raw material and the stirring conditions, even when the content ratio of the infrared absorption particles is 15% by mass or more, coating and encapsulation with resin can be performed. However, depending on the type of such emulsifier, etc., these conditions change, so there is no particular limitation, and it is preferable to conduct preliminary tests and select appropriate conditions.

[0130] (d) Polymerization initiator

[0131] As the polymerization initiator, one or more selected from various polymerization initiators such as radical polymerization initiators and ionic polymerization initiators can be used, and there is no particular limitation.

[0132] As the radical polymerization initiator, azo compounds, dihalogens, organic peroxides, etc. can be cited. In addition, hydrogen peroxide and iron (II) salts, redox initiators combining oxidants and reducing agents such as persulfates and sodium bisulfite can be cited.

[0133] Examples of ionic polymerization initiators include nucleophiles such as n-butyllithium, protic acids, Lewis acids, halogen molecules, and electrophiles such as carbocations.

[0134] When a cationic or non-ionic polymerization initiator is used as a radical polymerization initiator, infrared-absorbing particles can be efficiently coated.

[0135] Therefore, when a radical polymerization initiator is used as a polymerization initiator, one or more selected from cationic polymerization initiators, non-ionic polymerization initiators, etc. can be suitably used.

[0136] Examples of non-ionic polymerization initiators include oil-soluble non-ionic polymerization initiators and water-soluble non-ionic polymerization initiators.

[0137] Examples of oil-soluble non-ionic polymerization initiators include 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), (dimethyl 1,1'-azobis(1-cyclohexanecarboxylate)), dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis(N-butyl-2-methylpropionamide), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], etc.

[0138] Examples of water-soluble non-ionic polymerization initiators include 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis[2-(2-imidazolin-2-yl)propane], etc.

[0139] Examples of cationic polymerization initiators include 2,2'-azobis-(2-(1,3-dimethyl-4,5-dihydro-1H-imidazol-3-ium-2-yl))propane triphthalate (ADIP) which always shows stable cationicity regardless of pH and ADIP-Cl in which its counter anion is exchanged for chloride ion, and 2,2'-azobis(2-methylpropamidine) dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] disulfate-dihydrate, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropamidine] tetrahydrate, etc. which are protonated from acidic to neutral regions in an aqueous environment and show cationicity.

[0140] As a radical polymerization initiator, a cationic polymerization initiator can be more suitably used.

[0141] When a cationic polymerization initiator is used as a radical polymerization initiator, in the obtained organic-inorganic hybrid infrared absorbing particles, the surface of the infrared absorbing particles can be coated particularly uniformly with a resin. It is considered that the above effect is based on the affinity between the polymer matrix generated by polymerization and the infrared absorbing particles. When a cationic polymerization initiator, that is, a polymerization initiator showing cationicity, is used, it is considered that an oligomer or polymer having a cationic moiety at the end is adsorbed (grafted) onto the surface of the infrared absorbing particles by electrostatic interaction, thereby improving the affinity with the polymer matrix and increasing the affinity between the polymer matrix and the infrared absorbing particles. In contrast, when a nonionic polymerization initiator, that is, a polymerization initiator showing nonionicity, is used, it is considered that the electrostatic interaction is smaller than in the case of using a cationic polymerization initiator, and the affinity between the polymer matrix and the infrared absorbing particles is relatively reduced. Therefore, it is considered that the coating resin can coat the infrared absorbing particles more uniformly when a cationic polymerization initiator is used than when a nonionic polymerization initiator is used.

[0142] According to the research of the inventors of the present invention, the selection and combination of an emulsifier and a polymerization initiator sometimes affect the uniformity of the resin for coating infrared absorbing particles when coating the infrared absorbing particles. Specifically, by the selection and combination of an emulsifier and a polymerization initiator, for example, there are cases where the infrared absorbing particles can be coated uniformly, cases where the infrared absorbing particles are coated with deviation, etc. Therefore, it is preferable to select the combination of an emulsifier and a polymerization initiator according to the required characteristics of the organic-inorganic hybrid infrared absorbing particles and the like.

[0143] When preparing the raw material mixture, the polymerization initiator can be added to the organic phase or the aqueous phase according to its type. For example, when using 2,2'-azobisisobutyronitrile, it can be added to the organic phase. In addition, when using 2,2'-azobis(2-methylpropionamidine) dihydrochloride, it can be added to the aqueous phase.

[0144] In the raw material mixture preparation step, as long as the infrared absorbing particles recovered after the dispersion medium reduction step, the coating resin raw material, the organic solvent, the emulsifier, the water, and the polymerization initiator can be mixed to prepare the raw material mixture. Therefore, the preparation steps of the raw material mixture and the like are not particularly limited. For example, a mixture containing an emulsifier can be prepared in advance as the aqueous phase. In addition, as the organic phase, a mixture in which the coating resin raw material and the infrared absorbing particles recovered after the dispersion medium reduction step are dispersed in the organic solvent can be prepared.

[0145] In addition, the polymerization initiator can be added to the aqueous phase or the organic phase as described above according to the type of the polymerization initiator used.

[0146] Moreover, it is possible to add and mix an organic phase in an aqueous phase, thereby preparing a raw material mixture.

[0147] In addition, in the raw material mixture preparation step, with respect to the obtained organic-inorganic hybrid infrared absorbing particles, it is preferable to mix the raw materials such that the content ratio of the infrared absorbing particles is 15% by mass or more and 55% by mass or less.

[0148] Preferably, after adding the organic phase to the aqueous phase, sufficient stirring is performed so that the resin for coating can be more uniformly disposed on the surface of the infrared absorbing particles. That is, in the raw material mixture preparation step, in addition to the mixing step of mixing the infrared absorbing particles recovered after the dispersion medium reduction step, the resin raw material for coating, the organic solvent, the emulsifier, water, and the polymerization initiator, it is preferable to further include a stirring step of stirring the obtained mixture.

[0149] In the stirring step, for example, a stirrer can be used for stirring. In the case of performing the stirring step, the degree of stirring is not particularly limited. For example, it is preferably performed such that water-in-oil droplets in which the infrared absorbing particles included in the resin raw material for coating are dispersed in the aqueous phase are formed. In addition, the stirring step may not be performed and may be performed together in the subsequent stirring step.

[0150] The addition amount of the polymerization initiator is not particularly limited and can be arbitrarily selected. The addition amount of the polymerization initiator can be selected according to the resin raw material for coating, the type of the polymerization initiator, the size of the oil droplets as the microemulsion, the ratio of the resin raw material for coating to the infrared absorbing particles, etc. For example, if the addition amount of the polymerization initiator is 0.01 mol% or more and 1000 mol% or less with respect to the resin raw material for coating, it is easy to obtain the organic-inorganic hybrid infrared absorbing particles in which the infrared absorbing particles are sufficiently covered with the resin for coating, and thus it is preferable. The addition amount of the polymerization initiator is more preferably 0.1 mol% or more and 200 mol% or less with respect to the resin raw material for coating, and further preferably 0.2 mol% or more and 100 mol% or less.

[0151] (4) Stirring step

[0152] In the stirring step, while cooling the raw material mixture obtained in the raw material mixture preparation step, stirring can be performed.

[0153] The degree of stirring in the stirring step is not particularly limited and can be arbitrarily selected. For example, it is preferably performed such that the size of the water-in-oil droplets of the O / W type emulsion in which the resin raw material for coating containing the infrared absorbing particles is dispersed in the aqueous phase becomes a microemulsion of a predetermined size.

[0154] The microemulsion is obtained by adding a substance that is hardly soluble in water, i.e., a water solvent, to an organic phase and applying strong shear force. As the water solvent, for example, the organic solvent described above in the raw material mixture preparation step can be cited.

[0155] In the stirring step, it is preferable to stir the obtained microemulsion in such a manner as to have particle size characteristics corresponding to the target organic-inorganic hybrid infrared absorbing particles.

[0156] In the stirring step, specifically, for example, in the particle size distribution based on the scattering intensity measured by the dynamic light scattering method for the microemulsion, it is preferable to stir in such a manner as to have one peak. That is, in the stirring step, the above-mentioned particle size distribution of the obtained microemulsion preferably does not have two or more peaks. When the particle size distribution of the microemulsion obtained by the stirring step is represented by one peak, the dispersibility in various media such as the dispersion medium is excellent for the organic-inorganic hybrid infrared absorbing particles manufactured using the microemulsion. Therefore, it is possible to easily form an infrared absorbing particle dispersion liquid, an infrared absorbing particle dispersion, a composition for anti-counterfeiting ink, etc. (hereinafter, also referred to as "infrared absorbing particle dispersion liquid, etc.") using the organic-inorganic hybrid infrared absorbing particles. In addition, the infrared absorbing characteristics of the obtained infrared absorbing particle dispersion liquid, etc. can be particularly improved.

[0157] Preferably, for the microemulsion obtained by the stirring step, in the particle size distribution based on the scattering intensity measured by the dynamic light scattering method, the median diameter D50 is 1 μm or less and the standard deviation is 500 or less.

[0158] By making D50 1 μm or less, the dispersibility can be particularly improved when the organic-inorganic hybrid infrared absorbing particles manufactured using the microemulsion are made into an infrared absorbing particle dispersion liquid, etc. In addition, by making the standard deviation 500 or less, the expansion of the particle size distribution of the organic-inorganic hybrid infrared absorbing particles manufactured using the microemulsion can be particularly suppressed. Therefore, when using the organic-inorganic hybrid infrared absorbing particles to make an infrared absorbing particle dispersion liquid, etc., it is possible to easily disperse the organic-inorganic hybrid infrared absorbing particles uniformly in the infrared absorbing particle dispersion liquid, etc., and particularly improve the infrared absorbing characteristics.

[0159] The above D50 is more preferably 800 nm or less, and further preferably 500 nm or less. The lower limit value of D50 is not particularly limited, and from the viewpoint of containing a sufficient amount of infrared absorbing particles, it is preferably 30 nm or more, more preferably 50 nm or more, further preferably 100 nm or more, and particularly preferably 150 nm or more.

[0160] The above standard deviation is more preferably 400 or less, still more preferably 300 or less, and particularly preferably 250 or less. The lower limit value of the above standard deviation is not particularly limited. For example, it is preferably 20 or more, more preferably 50 or more, and still more preferably 100 or more. By making the above standard deviation 20 or more, the productivity of the microemulsion can be improved.

[0161] In the stirring step, the specific conditions for producing the microemulsion having the above particle size characteristics are not particularly limited. For example, depending on the type and addition amount of the emulsifier, etc., the conditions of the stirring tank such as volume and the presence or absence of baffles, the stirring power, and the type of stirring means used can be selected so as to apply an appropriate stirring force to the raw material mixture. In addition, the stirring step can also be carried out in multiple times while changing the stirring conditions. Furthermore, it is preferable to conduct preliminary tests in the stirring step to select appropriate conditions.

[0162] In the stirring step, it is preferable to stir while cooling the raw material mixture as described above. This is because by cooling the raw material mixture, the polymerization reaction can be suppressed while forming a microemulsion.

[0163] In addition, the degree of cooling the raw material mixture is not particularly limited. For example, it is preferably cooled using a cooling medium at 0°C or lower, such as by an ice bath.

[0164] (5) Polymerization step

[0165] In the polymerization step, after performing a deoxidation treatment to reduce the amount of oxygen in the raw material mixture, the polymerization reaction of the resin raw material for coating can be carried out.

[0166] In the polymerization step, the polymerization of the resin raw material for coating can be carried out, and the resin for coating is disposed on at least a part of the surface of the infrared absorption particles. At this time, it is preferable to produce organic-inorganic hybrid infrared absorption particles in which infrared absorption particles are disposed in resin capsules through the polymerization step.

[0167] The conditions in the polymerization step are not particularly limited. A deoxidation treatment to reduce the amount of oxygen in the raw material mixture can be carried out before starting the polymerization. The specific method of the deoxidation treatment is not particularly limited, and examples include a method of performing ultrasonic irradiation and a method of blowing an inert gas into the raw material mixture.

[0168] Moreover, the specific conditions for carrying out the polymerization reaction can be arbitrarily selected according to the resin raw material for coating added to the raw material mixture, etc., and thus are not particularly limited. For example, the raw material mixture can be heated or light of a predetermined wavelength can be irradiated, etc., to carry out the polymerization reaction.

[0169] According to the method for manufacturing the organic-inorganic hybrid infrared absorption particles of the present embodiment described above, it is possible to dispose an organic material such as resin on at least a part of the surface of the infrared absorption particles, which has been difficult in the past, to obtain organic-inorganic hybrid infrared absorption particles. Therefore, even when exposed to a chemical environment such as high-temperature acid or alkali, it is possible to prevent the infrared absorption particles from directly contacting chemical components such as acid or alkali, and the chemical resistance is excellent, and it is possible to suppress a decrease in the infrared absorption characteristics.

[0170] In addition, according to the method for manufacturing the organic-inorganic hybrid infrared absorption particles of the present embodiment, it is possible to manufacture organic-inorganic hybrid infrared absorption particles in which the content ratio of the infrared absorption particles is as high as 15% by mass or more, which has been particularly difficult in the past. Therefore, it is possible to obtain organic-inorganic hybrid infrared absorption particles having excellent infrared shielding characteristics in addition to chemical resistance.

[0171] 2. Organic-inorganic hybrid infrared absorption particles

[0172] The organic-inorganic hybrid infrared absorption particles will be described. The organic-inorganic hybrid infrared absorption particles can have infrared absorption particles and a coating resin that covers at least a part of the surface of the infrared absorption particles. Additionally, it is more preferable that the coating resin forms a resin capsule, and the infrared absorption particles are disposed in the resin capsule. That is, it is more preferable that the entire surface of the infrared absorption particles is covered with the coating resin. The organic-inorganic hybrid infrared absorption particles can be manufactured, for example, by the method for manufacturing the organic-inorganic hybrid infrared absorption particles described above. Therefore, some of the matters that have already been described will be omitted from the description.

[0173] By disposing a coating resin that covers at least a part of the surface on the surface of the infrared absorption particles, which has been difficult in the past, it is possible to prevent the infrared absorption particles from directly contacting chemical components such as acid or alkali even when exposed to a chemical environment such as high-temperature acid or alkali. Therefore, the organic-inorganic hybrid infrared absorption particles according to the present embodiment have excellent chemical resistance and can suppress a decrease in the infrared absorption characteristics.

[0174] In the past, it has been difficult to dispose an organic material such as resin on the surface of infrared absorption particles, and in particular, no research has been conducted on increasing the content ratio of infrared absorption particles. In contrast, the inventors of the present invention conducted research and found that by making organic-inorganic hybrid infrared absorption particles in which the content ratio of infrared absorption particles is a predetermined ratio or more, it is possible to produce an infrared shielding material having both chemical resistance and infrared shielding characteristics.

[0175] Figure 2 FIG. shows a cross-sectional schematic view of the organic-inorganic hybrid infrared absorption particles 20 of the present embodiment. Figure 2As shown, the organic-inorganic hybrid infrared absorption particles 20 of the present embodiment have a coating resin 22 disposed on at least a part of the surface of the infrared absorption particles 21.

[0176] In addition, particularly Figure 2 As shown, it is preferable that the organic-inorganic hybrid infrared absorption particles 20 of the present embodiment have a structure in which the infrared absorption particles 21 are disposed in a resin capsule 221 formed by the coating resin 22. Figure 2 As shown, a plurality of infrared absorption particles 21 may be disposed in one resin capsule 221, or only one may be disposed. In addition, the infrared absorption particles 21 may be present offset within the resin capsule 221 and are preferably dispersed.

[0177] It is sufficient that at least a part of the infrared absorption particles 21 is covered by the resin capsule 221, and a part of the infrared absorption particles 21 may be exposed from the resin capsule 221 to the outer surface. However, the infrared absorption particles 21 are preferably completely covered by the resin capsule 221, that is, enclosed in the resin capsule 221. This is because when the infrared absorption particles 21 are completely covered by the resin capsule 221, even when the organic-inorganic hybrid infrared absorption particles come into contact with various chemical components, the infrared absorption particles 21 can more reliably prevent contact with the chemicals, especially improving chemical resistance.

[0178] In addition, Figure 2 The organic-inorganic hybrid infrared absorption particles 20 shown are merely schematically shown for illustration, and the organic-inorganic hybrid infrared absorption particles of the present embodiment are not limited to such a form. For example, the shape, size, arrangement, distribution of the infrared absorption particles 21, the shape, arrangement, etc. of the coating resin 22 are not limited to such a form.

[0179] (1) Each component of the organic-inorganic hybrid infrared absorption particles (1-1) Infrared absorption particles

[0180] Regarding the infrared absorption particles, it has been described in the manufacturing method of the organic-inorganic hybrid infrared absorption particles, so the description is omitted. As the organic-inorganic hybrid infrared absorption particles, for example, infrared absorption particles containing various materials having free electrons are preferably used, and more preferably infrared absorption particles containing various inorganic materials having free electrons can be used.

[0181] Particularly preferably, infrared absorption particles containing one or more selected from tungsten oxides having oxygen deficiencies and composite tungsten oxides can be used as the infrared absorption particles. In this case, specifically, the infrared absorption particles preferably contain, for example, tungsten oxides represented by the general formula W y O z (W: tungsten, O: oxygen, 2.2 ≤ z / y ≤ 2.999) and those represented by the general formula Mx W y O z (Element M is one or more selected from H, He, Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Hf, Os, Bi, I, 0.001 ≤ x / y ≤ 1, 2.0 ≤ z / y < 4.0) and is one or more of the composite tungsten oxides shown below.

[0182] The organic-inorganic hybrid infrared absorption particles can make the content ratio of the infrared absorption particles 15% by mass or more and 55% by mass or less. By making the content ratio of the infrared absorption particles 15% by mass or more, the anti-counterfeiting ink composition containing the organic-inorganic hybrid infrared absorption particles can exhibit excellent infrared absorption characteristics. In addition, by making the content ratio of the infrared absorption particles 55% by mass or less, at least a part of the surface of the infrared absorption particles can be surely coated with the coating resin, and the chemical resistance of the anti-counterfeiting ink composition containing the organic-inorganic hybrid infrared absorption particles can be improved.

[0183] (1-2) Coating resin

[0184] Regarding the coating resin, it has been described in the manufacturing method of the organic-inorganic hybrid infrared absorption particles, so the description is omitted here. For example, one or more resins selected from thermoplastic resins, thermosetting resins, photocurable resins, etc. can be used. As the coating resin, it is particularly preferable to contain one or more selected from polyester resins, polycarbonate resins, acrylic resins, polystyrene resins, polyamide resins, vinyl chloride resins, olefin resins, fluororesins, polyvinyl acetate resins, polyurethane resins, acrylonitrile-butadiene-styrene resins, polyvinyl acetal resins, acrylonitrile-styrene copolymer resins, ethylene-vinyl acetate copolymer resins, phenolic resins, epoxy resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, polyimide resins, silicone resins. In addition, as the above-mentioned polyurethane resin, both thermoplastic polyurethane resins and thermosetting polyurethane resins can be used.

[0185] In addition, as the coating resin, a photocurable resin can also be suitably used. As described above, a resin that cures upon irradiation with any of ultraviolet light, visible light, and infrared light can be suitably used.

[0186] Among them, as the coating resin, a resin applicable to the microemulsion polymerization method is preferred, and for example, a polystyrene resin is more preferably contained.

[0187] As described above, the organic-inorganic hybrid infrared absorbing particles are disposed on at least a part of the surface of the infrared absorbing particles, which was difficult in the past, as a coating resin made of an organic material. Therefore, even when exposed to a chemical environment such as high-temperature acid or alkali, it is possible to prevent the infrared absorbing particles from directly contacting chemical components such as acid or alkali, so the chemical resistance is excellent and a decrease in the infrared absorption characteristics can be suppressed. Moreover, the anti-counterfeiting ink composition using the organic-inorganic hybrid infrared absorbing particles can also have chemical resistance.

[0188] In the anti-counterfeiting ink composition of the present embodiment, in addition to the organic-inorganic hybrid infrared absorbing particles, any other components can be further contained. The anti-counterfeiting ink composition can also contain, for example, a liquid medium, a dispersant, a surfactant, etc., as described below.

[0189] 3. Liquid Medium

[0190] The anti-counterfeiting ink composition of the present embodiment can further contain a liquid medium.

[0191] The anti-counterfeiting ink composition of the present embodiment contains a liquid medium, so that the anti-counterfeiting ink composition of the present embodiment can be easily printed on a printing substrate or the like. The liquid medium preferably contains the organic-inorganic hybrid infrared absorbing particles inside and is dispersed. Therefore, the liquid medium can also be referred to as a dispersion medium or a solvent.

[0192] Therefore, for example Figure 3 As schematically shown, the anti-counterfeiting ink composition 30 of the present embodiment can contain the above-described organic-inorganic hybrid infrared absorbing particles 31 and a liquid medium 32.

[0193] In addition Figure 3 For the schematic diagram shown, the anti-counterfeiting ink composition of the present embodiment is not limited to such a form. For example Figure 3 In the figure, the organic-inorganic hybrid infrared absorbing particles 31 are represented by circles and described as spherical particles, but the shape of the organic-inorganic hybrid infrared absorbing particles 31 is not limited to such a form and can have any shape. In addition Figure 3In this case, the description of the infrared absorption particles in the organic-inorganic hybrid infrared absorption particles is omitted. In the anti-counterfeiting ink composition 30, in addition to the organic-inorganic hybrid infrared absorption particles 31 and the liquid medium 32, other additives such as a dispersant can be included as needed.

[0194] In addition, the liquid medium only needs to be a material that can impart fluidity suitable for the printing method to the anti-counterfeiting ink composition when the anti-counterfeiting ink composition of the present embodiment is used by printing or the like, and is not particularly limited.

[0195] The liquid medium is not particularly limited, and for example, a liquid medium containing one or more selected from water, alcohols such as ethanol, ketones such as methyl ethyl ketone, ester solvents such as 3-methyl-methoxy-propionate, glycol derivatives such as propylene glycol monomethyl ether acetate, aromatic hydrocarbons such as toluene and xylene, amides such as formamide, chlorinated compounds such as chlorobenzene, vegetable oils, vegetable oil-derived compounds, and petroleum solvents can be used.

[0196] Examples of the vegetable oil include drying oils such as linseed oil, sunflower oil, and tung oil, semi-drying oils such as sesame oil, cottonseed oil, rapeseed oil, soybean oil, and rice bran oil, and non-drying oils such as olive oil, coconut oil, palm oil, and dehydrated castor oil.

[0197] Examples of the vegetable oil-derived compounds include fatty acid monoesters and ethers formed by directly esterifying the fatty acids of vegetable oils with monohydric alcohols.

[0198] Examples of the petroleum solvents include Isopar E, EXXSOL Hexane, EXXSOL Heptane, EXXSOL E, EXXSOL D30, EXXSOL D40, EXXSOL D60, EXXSOL D80, EXXSOL D95, EXXSOL D110, EXXSOL D130 (all of the above are manufactured by ExxonMobil) with a high aniline point. In addition, mineral oil and the like can also be cited as the petroleum solvent.

[0199] When adding the liquid medium, the liquid medium can be selected according to the anti-counterfeiting ink composition, the properties required for the anti-counterfeiting ink containing the anti-counterfeiting ink composition, and the purpose of use, and is not particularly limited.

[0200] When the anti-counterfeiting ink composition of the present embodiment contains a liquid medium, the specific method of dispersing the organic-inorganic hybrid infrared absorbing particles in the liquid medium is not particularly limited. For example, in order to prepare the anti-counterfeiting ink described later, the same methods as those for dispersing the anti-counterfeiting ink composition in the uncured product of the liquid of the energy ray-curable resin can be used, such as ultrasonic waves, a media agitation mill, etc. Specifically, for example, devices such as a bead mill, a ball mill, a sand mill, a paint shaker, an ultrasonic homogenizer can be used. In addition, when dispersing the organic-inorganic hybrid infrared absorbing particles in the liquid medium, it is preferable to select the dispersion conditions so as not to peel off the coating resin as an organic material disposed on the surface of the infrared absorbing particles.

[0201] 4. Dispersant, Surfactant

[0202] Next, the dispersant and the surfactant will be described.

[0203] The anti-counterfeiting ink composition of the present embodiment can contain one or more selected from a dispersant and a surfactant. The dispersant and the surfactant are not particularly limited as long as they can disperse the above-mentioned organic-inorganic hybrid infrared absorbing particles in the anti-counterfeiting ink composition. When the anti-counterfeiting ink composition of the present embodiment contains a dispersant, as the dispersant, for example, a copolymer having an amine-based functional group and a polyether structure can be included. Examples of the copolymer having an amine-based functional group and a polyether structure include Solsperse (registered trademark) 20000 manufactured by Lubrizol Corporation of Japan, Disperbyk (registered trademark) -161, 162, 163, 182, 184, 185 manufactured by BYK Japan Co., Ltd., and Disparon (registered trademark) DA-234, DA-325 manufactured by Kusumoto Chemicals, Ltd. In addition, when the anti-counterfeiting ink composition of the present embodiment contains a surfactant, as the surfactant, for example, dodecyltrimethylammonium chloride can be used.

[0204] 5. Other Additive Ingredients

[0205] The anti-counterfeiting ink composition of the present embodiment can further contain arbitrary additive ingredients as needed.

[0206] The anti-counterfeiting ink composition of the present embodiment can also contain one or more selected from coloring pigments, dyes, etc.

[0207] [Anti-counterfeiting Ink]

[0208] The anti-counterfeiting ink of the present embodiment can contain the above-mentioned anti-counterfeiting ink composition and the uncured product of the liquid of the energy ray-curable resin.

[0209] The liquid uncured material of the energy ray-curable resin is not particularly limited, and for example, an uncured material of a resin that is cured by irradiation with any of ultraviolet rays, visible rays, and infrared rays can be used.

[0210] The liquid uncured material of the resin cured by energy rays may be liquid when applied to a substrate to be printed, that is, have fluidity to the extent that it can be applied to a substrate to be printed.

[0211] The method of dispersing the composition for anti-counterfeiting ink into an uncured material of a liquid resin cured by energy rays to obtain the anti-counterfeiting ink is not particularly limited.

[0212] As means (methods) for dispersing the composition for forgery prevention ink into the uncured liquid of the resin cured by energy rays, means using ultrasonic waves, medium stirring mills, etc. can be cited. As the medium stirring mill, bead mills, ball mills, sand mills, paint shakers, etc. using media (beads, balls, Ottawa sand) can be cited. By using ultrasonic waves, medium stirring mills, etc. to disperse the composition for forgery prevention ink, it is possible to disperse organic-inorganic hybrid infrared absorbing particles, etc., particularly uniformly into the uncured liquid of the resin cured by energy rays, and therefore it is preferred.

[0213] Therefore, as a dispersion treatment method for dispersing organic-inorganic hybrid infrared absorbing particles in an uncured material of a liquid resin cured by energy rays, there can be cited a dispersion treatment method using a bead mill, a ball mill, a sand mill, a paint shaker, an ultrasonic homogenizer, or the like.

[0214] However, if a medium stirring mill is used, the organic-inorganic hybrid infrared absorbing particles may be dispersed into the uncured material of the liquid resin cured by energy rays, and micronization may be performed by collision of the organic-inorganic hybrid infrared absorbing particles with each other or the medium with the particles. Therefore, it is preferable to select stirring conditions in such a way that the coating resin as an organic material disposed on the surface of the infrared absorbing particles is not peeled off by excessive micronization. In the case of using a medium stirring mill for dispersion treatment, for example, it is preferable to reduce the diameter of the medium or to shorten the time of pulverization and dispersion treatment to an extremely short value.

[0215] In addition, the forgery prevention ink of the present embodiment can further contain any component as needed. The forgery prevention ink of the present embodiment can further contain, for example, an organic binder. The forgery prevention ink contains an organic binder, so that when the forgery prevention ink of the present embodiment is applied, printed, etc., to form a printed portion on a printed substrate, it is particularly possible to suppress the peeling of the printed portion, or the falling off of organic-inorganic hybrid infrared absorbing particles, etc. As the organic binder, for example, one or more selected from polyvinyl butyral, polyvinyl formal, etc. can be suitably used.

[0216] As described above, the organic-inorganic hybrid infrared absorption particles contained in the anti-counterfeiting ink of the present embodiment can prevent the infrared absorption particles from directly contacting chemical components such as acids or alkalis even when exposed to a high-temperature chemical environment such as an acid or an alkali. Therefore, the organic-inorganic hybrid infrared absorption particles have excellent chemical resistance and can suppress the reduction of infrared absorption characteristics. Moreover, the anti-counterfeiting ink of the present embodiment containing the organic-inorganic hybrid infrared absorption particles can have chemical resistance.

[0217] [Printed matter for anti-counterfeiting]

[0218] (1) Regarding the constitution of the printed matter for anti-counterfeiting

[0219] The printed matter for anti-counterfeiting of the present embodiment can have a printed portion containing the above-described anti-counterfeiting ink composition.

[0220] The printed portion of the printed matter for anti-counterfeiting of the present embodiment can be obtained by coating or printing, for example, the above-described anti-counterfeiting ink composition or anti-counterfeiting ink on the surface of the substrate to be printed by a general method. Since the anti-counterfeiting ink composition or anti-counterfeiting ink can be printed on the substrate to be printed in a film form, for example, in this case, the printed portion can also be referred to as a printed film.

[0221] The method for forming the printed matter for anti-counterfeiting of the present embodiment, that is, the method of coating or printing the above-described anti-counterfeiting ink composition or anti-counterfeiting ink on the surface of the substrate to be printed is not particularly limited. As the printing method of the above-described anti-counterfeiting ink composition or anti-counterfeiting ink, one or more selected from, for example, lithography, letterpress printing, flexographic printing, letterpress printing (resin relief printing), gravure printing, screen printing, inkjet printing, etc. can be cited.

[0222] The printed portion of the printed matter for anti-counterfeiting can be formed, for example, by removing the liquid medium by evaporation or the like from the above-described anti-counterfeiting ink composition or anti-counterfeiting ink that has been coated or the like, and adhering solid components such as organic-inorganic hybrid infrared absorption particles to the surface of the substrate to be printed. In addition, at least a part of the liquid medium may remain in the printed portion.

[0223] In addition, such a printed portion can also cure the uncured liquid of the resin cured by energy rays contained in the anti-counterfeiting ink by irradiating energy rays, and adhere organic-inorganic hybrid infrared absorption particles or the like to the substrate to be printed to form.

[0224] In addition, as described above, the forgery-preventing ink can also contain an organic binder. In this case, the printing section of the forgery-preventing printed matter of the present embodiment can also contain an organic binder. When the forgery-preventing ink contains an organic binder, it is preferable to cure the organic binder by conditions selected according to the type of the organic binder after coating or printing the forgery-preventing ink.

[0225] As described above, by coating or printing the forgery-preventing ink composition or the forgery-preventing ink on the substrate to be printed, the printing section is obtained as described above by performing the treatment corresponding to the contained components. If necessary, in order to prevent peeling of the printing section and falling off of the particles contained in the printing section, a covering layer containing a transparent resin or the like can be provided on the printing section.

[0226] The content of the infrared absorption particles in the printing section of the forgery-preventing printed matter can be changed according to the target use, and is usually preferably 0.05 g / m 2 The above. If it has a content of 0.05 g / m 2 or more, the absorption in the near-infrared region is significantly exhibited, and it exhibits a particularly high function as a forgery-preventing printed matter. In addition, the upper limit of the content is not particularly limited, and if it is 4 g / m 2 or less, the light in the visible light region is not significantly absorbed, and thus it is preferable from the viewpoint of maintaining transparency. In addition, the content of the above infrared absorption particles acts equally on the light incident on the printing surface of all the fillers, and thus can be evaluated by the content per 1 m 2 of the printing section.

[0227] The substrate to be printed for coating or printing the forgery-preventing ink composition or the forgery-preventing ink can be any material that suits the target use. In addition to paper, a mixture of resin and pulp, a resin film, etc. can be used. In addition, the above-described forgery-preventing ink composition or forgery-preventing ink can be printed on a seal, and the seal can be pasted on the substrate to be printed.

[0228] In addition, in the forgery-preventing printed matter of the present embodiment, in addition to the printing section containing the above-described forgery-preventing ink composition, it can also include a portion printed with various inks used in ordinary printed matter.

[0229] The forgery-preventing printed matter of the present embodiment produced by such an operation cannot be replicated by copying or the like. Without visual determination, the authenticity can be mechanically and surely determined by irradiating infrared rays and detecting the reflection or transmission thereof. Moreover, an organic-inorganic hybrid infrared absorption particle is used as the infrared absorption material and applied to the substrate to be printed by a printing method, so that a forgery-preventing printed matter having excellent infrared absorption characteristics and chemical resistance and being inexpensive can be provided.

[0230] (2) Regarding the near-infrared absorption effect of anti-counterfeiting printed matter

[0231] When the substrate of the anti-counterfeiting printed matter using the above-mentioned anti-counterfeiting ink composition or anti-counterfeiting ink is woodfree paper, if the reflectance at a wavelength of 1000 nm is less than 50%, it indicates excellent near-infrared absorption effect.

[0232] (3) Regarding the chemical resistance of anti-counterfeiting printed matter

[0233] The anti-counterfeiting printed matter of this embodiment using the above-mentioned anti-counterfeiting ink composition and anti-counterfeiting ink has excellent chemical resistance. Therefore, even if the anti-counterfeiting printed matter of this embodiment is immersed in, for example, a 0.01 mol / L sodium hydroxide aqueous solution maintained at 80 °C for 30 minutes, the difference in reflectance before and after the chemical resistance test at the above-mentioned wavelength of 1000 nm is maintained at 1.3% or less. That is, the anti-counterfeiting printed matter of this embodiment can have chemical resistance.

[0234] Examples

[0235] Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples.

[0236] In addition, the optical properties of the printed portions of the anti-counterfeiting printed matter obtained from the examples and comparative examples were measured using a spectro-brightness meter U-4100 (manufactured by Hitachi, Ltd.).

[0237] The measurement of the microcrystalline diameter of the infrared absorption particles was performed using the dry powder of the infrared absorption particles obtained by removing the solvent from the dispersion liquid of the infrared absorption particles. Then, the X-ray diffraction pattern of the infrared absorption particles was measured by the powder X-ray diffraction method (θ-2θ method) using a powder X-ray diffractometer (D2 PHASER manufactured by BRUKER AXS GmbH). Moreover, the crystal structure contained in the infrared absorption particles was specified from the obtained X-ray diffraction pattern, and further, the microcrystalline diameter was calculated using the Rietveld method.

[0238] [Example 1]

[0239] Through the following steps, an anti-counterfeiting ink composition and an anti-counterfeiting printed matter were produced and evaluated.

[0240] 1. Manufacture of organic-inorganic hybrid infrared absorption particles

[0241] The organic-inorganic hybrid infrared absorption particles used in the anti-counterfeiting ink composition were manufactured according to the following process.

[0242] (Dispersion Liquid Preparation Process)

[0243] In the dispersion liquid preparation process, a dispersion liquid containing infrared absorption particles, a dispersant, and a dispersion medium is prepared.

[0244] As the infrared absorption particles, hexagonal cesium tungsten bronze (Cs 0.33 WO z , 2.0 ≤ z < 4.0) composite tungsten oxide powder with a molar ratio of cesium (Cs) to tungsten (W) of Cs / W = 0.33 is prepared.

[0245] As the dispersant, a polymer dispersant which is a copolymer of styrene and 2-(dimethylamino)ethyl methacrylate is prepared.

[0246] In addition, as the dispersion medium, toluene is prepared.

[0247] Moreover, a mixed liquid obtained by mixing 20% by mass of infrared absorption particles, 6% by mass of the dispersant, and 74% by mass of the dispersion medium is filled into a paint shaker containing 0.3 mmφ ZrO 2 beads and subjected to a pulverization and dispersion treatment for 24 hours. Through the pulverization and dispersion treatment, a dispersion liquid of Cs 0.33 WO z particles according to Example 1 is obtained.

[0248] (Dispersion Medium Reduction Process)

[0249] From the dispersion liquid of Cs 0.33 WO z particles obtained in the dispersion liquid preparation process, using an evaporator, toluene as the dispersion medium is removed to recover the infrared absorption particles. The recovered infrared absorption particles become dry powder of Cs 0.33 WO z particles containing the polymer dispersant. That is, the recovered infrared absorption particles are infrared absorption particles with surface modification of the dispersant attached by the dispersion liquid preparation process on the surface of the particles, and become infrared absorption particles containing the dispersant.

[0250] The recovered infrared absorption particles, namely Cs 0.33 WO z particles, are measured for their microcrystalline diameter, and the result is 16 nm.

[0251] In addition, the microcrystalline diameter is measured and calculated by the method described above.

[0252] (Raw Material Mixture Preparation Process)

[0253] 12.9 g of infrared absorbing particles with surface modification of dispersant obtained by the dispersion medium reduction process were mixed with 30 g of styrene as the resin raw material for coating to prepare an organic phase. In addition, in this example, the infrared absorbing particles and other components were added and mixed so that the content ratio (target ratio) of the infrared absorbing particles in the finally obtained organic-inorganic hybrid infrared absorbing particles was 20% by mass.

[0254] To disperse the infrared absorbing particles with surface modification of dispersant in styrene, the above organic phase was mixed and dispersed.

[0255] Next, 2.09 g of hexadecane as an organic solvent was added to the organic phase, and further dispersion treatment was carried out.

[0256] In addition, separately from the above organic phase, 3 g of cetyltrimethylammonium chloride as an emulsifier, 300 g of water, and 1.56 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride as a polymerization initiator were mixed to form an aqueous phase. When forming the aqueous phase, cetyltrimethylammonium chloride as an emulsifier was added to water at a concentration 24 times the critical micelle concentration. In addition, the polymerization initiator was added at a ratio of 2.0 mol% with respect to styrene.

[0257] Then, the organic phase was added to the aqueous phase to prepare a raw material mixture. The addition amounts of the respective components in the raw material mixture preparation process are summarized in Table 1.

[0258] (Stirring process)

[0259] For the raw material mixture prepared by the raw material mixture preparation process, in an ice bath, stirring was carried out until there was 1 peak in the particle size distribution based on the scattering intensity measured by the dynamic light scattering method of the obtained microemulsion. At this time, in the above particle size distribution, D50 was 188 nm and the standard deviation was 119.

[0260] (Polymerization process)

[0261] After the stirring process, for the raw material mixture, nitrogen bubbling was carried out for 15 minutes in an ice bath for deoxidation treatment.

[0262] Then, under a nitrogen atmosphere, a heat treatment was carried out at 70 °C for 6 hours to carry out the polymerization reaction of styrene, and an organic-inorganic hybrid infrared absorbing particle dispersion was obtained.

[0263] The dispersion containing the obtained organic-inorganic hybrid infrared absorbing particles was diluted, transferred to a microgrid for TEM observation, and TEM observation of the transfer was carried out. As a result, it was confirmed that the infrared particles formed of composite tungsten oxide were encapsulated in polystyrene particles to form organic-inorganic hybrid infrared absorbing particles.

[0264] (Evaluation of particle size characteristics)

[0265] Using a particle size measuring device based on the dynamic light scattering method (ELSZ-2000 manufactured by Otsuka Electronics Co., Ltd.), the particle size distribution based on the scattering intensity of the obtained organic-inorganic hybrid infrared absorbing particles was measured. It was confirmed that the particle size distribution of the obtained organic-inorganic hybrid infrared absorbing particles had one peak. Moreover, the D50 as the median diameter and the standard deviation were calculated from the obtained particle size distribution. Table 2 shows the evaluation results.

[0266] (Content ratio of infrared absorbing particles)

[0267] TGA (thermogravimetric measurement) was performed, and the temperature was raised until the weight loss stopped to remove the resin component, and the mass of the infrared absorbing particles in the obtained organic-inorganic hybrid infrared absorbing particles was measured. Moreover, the content ratio of the measured infrared absorbing particles in the organic-inorganic hybrid infrared absorbing particles for evaluation was calculated, and the result was confirmed to be the added ratio, which was 20% by mass as the target ratio. In addition, even for the following other examples and comparative examples, the content ratio of the infrared absorbing particles in the organic-inorganic hybrid infrared absorbing particles was measured in the same way, and it was confirmed that the target composition was achieved.

[0268] 2. Composition for anti-counterfeiting ink

[0269] From the dispersion liquid containing the obtained organic-inorganic hybrid infrared absorbing particles, the solvent was removed by vacuum flow drying to obtain the dry powder of the organic-inorganic hybrid infrared absorbing particles related to Example 1. The obtained dry powder was mixed with a sheet sticking ink (best one medium manufactured by T&K TOKA Co., Ltd.) at a weight ratio of 1:30, and it was dispersed using a rotary mixer to obtain the composition for anti-counterfeiting ink related to Example 1.

[0270] In addition, the sheet sticking ink used contains mineral oil and vegetable oil equivalent to the liquid medium.

[0271] 3. Printed matter for anti-counterfeiting

[0272] As the printed substrate, coated paper was used, and the above composition for anti-counterfeiting ink was printed on its surface to obtain a printed matter for anti-counterfeiting containing a printed film (printing part).

[0273] (Evaluation of printed matter for anti-counterfeiting)

[0274] For the optical properties of the anti-counterfeiting printed matter, a spectrophotometer (U-4100 manufactured by Hitachi, Ltd.) was used to perform measurements by the reflection method. In addition, a white board (aluminum oxide) attached to the apparatus was set as the baseline of the reflectance.

[0275] When measuring the optical properties of the anti-counterfeiting printed matter, the reflectance of light with a wavelength of 1000 nm in the near-infrared region was 47%. The evaluation results were shown in the column of "Reflectance at 1000 nm wavelength before the chemical resistance test" in Table 2.

[0276] In addition, it means that the greater the reflectance at a predetermined wavelength, the smaller the absorption at that wavelength, and the smaller the reflectance at a predetermined wavelength, the greater the absorption at that wavelength. Therefore, compared with Reference Example 1 and the like described later, it can be confirmed that the anti-counterfeiting printed matter of Example 1 has excellent absorption characteristics of light with a wavelength of 1000 nm. In addition, in Example 1 and Reference Example 1, the reflectance at a wavelength of 1000 nm before the chemical resistance test was the same value, but in Reference Example 1, the addition amount of the organic-inorganic mixed infrared absorption particle dry powder when preparing the anti-counterfeiting ink composition was twice that of Example 1. Therefore, when comparing under the same conditions, it can be said that Example 1 has excellent absorption characteristics of light with a wavelength of 1000 nm compared with Reference Example 1.

[0277] (Chemical resistance test)

[0278] In addition, the obtained anti-counterfeiting printed matter was immersed in a 0.01 mol / L sodium hydroxide aqueous solution maintained at 80°C and stirred for 30 minutes to perform an alkali resistance test. When measuring the optical properties of the anti-counterfeiting printed matter after the alkali resistance test, the difference in the reflectance of light with a wavelength of 1000 nm before and after the alkali resistance test was 0.5%, showing almost no change, and it was confirmed that the infrared absorption characteristics were maintained and the chemical resistance characteristics were possessed. The difference in the evaluation results before and after the chemical resistance test was shown in the column of "Difference in reflectance at 1000 nm wavelength before and after the chemical resistance test" in Table 2.

[0279] Table 2 shows the evaluation results.

[0280] [Example 2]

[0281] In the raw material mixture preparation step, in addition to mixing 23.4 g of the infrared absorption particles with the surface modification of the dispersant obtained by the dispersion medium reduction step and 30 g of styrene as the resin raw material for coating, the operation was the same as in Example 1 to form an organic phase. In addition, the infrared absorption particles and other components were added and mixed so that the content ratio (target ratio) of the infrared absorption particles in the finally obtained organic-inorganic mixed infrared absorption particles in this example was 30% by mass.

[0282] In addition to the above, the organic-inorganic hybrid infrared absorbing particles, the composition for anti-counterfeiting ink, and the anti-counterfeiting printed matter related to Example 2 were produced by operating in the same manner as in Example 1, and evaluation was carried out.

[0283] In addition, in the stirring step, in the same manner as in Example 1, for the raw material mixture prepared in the raw material mixture preparation step, in an ice bath, in the particle size distribution based on the scattering intensity measured by the dynamic light scattering method of the obtained microemulsion, stirring was carried out until it became one peak. At this time, in the above particle size distribution of the microemulsion, D50 was 226 nm and the standard deviation was 141.

[0284] Table 2 shows the evaluation results.

[0285] [Example 3]

[0286] In the raw material mixture preparation step, in addition to mixing 39.7 g of the infrared absorbing particles with the surface modification of the dispersant obtained by the dispersant reduction step and 30 g of styrene as the raw material of the coating resin, an organic phase was formed by operating in the same manner as in Example 1. In addition, the infrared absorbing particles and other components were added and mixed so that the content ratio (target ratio) of the infrared absorbing particles in the finally obtained organic-inorganic hybrid infrared absorbing particles in this example became 40% by mass.

[0287] In addition to the above, the organic-inorganic hybrid infrared absorbing particles, the composition for anti-counterfeiting ink, and the anti-counterfeiting printed matter related to Example 3 were produced by operating in the same manner as in Example 1, and evaluation was carried out.

[0288] In addition, in the stirring step, for the raw material mixture prepared in the raw material mixture preparation step, in an ice bath, in the particle size distribution based on the scattering intensity measured by the dynamic light scattering method of the obtained microemulsion, stirring was carried out until it became one peak. At this time, in the above particle size distribution of the microemulsion, D50 was 222 nm and the standard deviation was 134.

[0289] Table 2 shows the evaluation results.

[0290] [Example 4]

[0291] In the raw material mixture preparation step, in addition to mixing 70.8 g of infrared absorption particles with the surface modification of the dispersant obtained by the dispersion medium reduction step and 30 g of styrene as the resin raw material for coating, an organic phase was formed in the same manner as in Example 1. In addition, 4.49 g of cetyltrimethylammonium chloride as an emulsifier, 300 g of water, and 1.56 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride as a polymerization initiator were mixed to form an aqueous phase. Further, when forming the aqueous phase, cetyltrimethylammonium chloride as an emulsifier was added to water at a concentration 36 times the critical micelle concentration.

[0292] In addition, the infrared absorption particles and other components were added and mixed so that the content ratio (target ratio) of the infrared absorption particles in the finally obtained organic-inorganic hybrid infrared absorption particles in this example was 50% by mass.

[0293] Except for the above, the organic-inorganic hybrid infrared absorption particles, the anti-counterfeiting ink composition, and the anti-counterfeiting printed matter according to Example 4 were produced in the same manner as in Example 1 and evaluated.

[0294] In addition, in the stirring step, for the raw material mixture prepared in the raw material mixture preparation step, in an ice bath, in the particle size distribution based on the scattering intensity measured by the dynamic light scattering method of the obtained microemulsion, stirring was performed until there was one peak. At this time, in the above particle size distribution of the microemulsion, D50 was 217 nm and the standard deviation was 144.

[0295] Table 2 shows the evaluation results.

[0296] [Examples 5 to 12]

[0297] In the raw material mixture preparation step, when forming the organic phase and the aqueous phase, the addition ratios of the respective components were the values shown in Table 1.

[0298] The infrared absorption particles and other components were added and mixed so that the content ratio (target ratio) of the infrared absorption particles in the finally obtained organic-inorganic hybrid infrared absorption particles in Examples 5 to 12 was 30% by mass.

[0299] Except for the above, the organic-inorganic hybrid infrared absorption particles, the anti-counterfeiting ink composition, and the anti-counterfeiting printed matter according to Examples 5 to 12 were produced in the same manner as in Example 1 and evaluated.

[0300] In addition, in the stirring step, for the raw material mixture prepared in the raw material mixture preparation step, in an ice bath, in the particle size distribution based on the scattering intensity measured by the dynamic light scattering method of the obtained microemulsion, stirring is performed until it becomes one peak. At this time, for the above-mentioned particle size distribution of the microemulsion, D50 and the standard deviation become the same values as the evaluation results of the organic-inorganic hybrid infrared absorbing particles shown in Table 2 for each example. That is, for example, in the case of Example 5, D50 is 203 nm and the standard deviation is 147.

[0301] Table 2 shows the evaluation results.

[0302] [Example 13]

[0303] In the raw material mixture preparation step, when forming the organic phase and the aqueous phase, the addition ratios of the respective components are the values shown in Table 1.

[0304] The infrared absorbing particles and other components are added and mixed in such a way that the content ratio (target ratio) of the infrared absorbing particles in the organic-inorganic hybrid infrared absorbing particles finally obtained in this example becomes 40% by mass.

[0305] Except for the above, the organic-inorganic hybrid infrared absorbing particles, the anti-counterfeiting ink composition, and the anti-counterfeiting printed matter were manufactured in the same manner as in Example 1 and evaluated.

[0306] In addition, in the stirring step, for the raw material mixture prepared in the raw material mixture preparation step, in an ice bath, in the particle size distribution based on the scattering intensity measured by the dynamic light scattering method of the obtained microemulsion, stirring is performed until it becomes one peak. At this time, in the above-mentioned particle size distribution of the microemulsion, D50 is 235 nm and the standard deviation is 155.

[0307] Table 2 shows the evaluation results.

[0308] [Reference Example 1]

[0309] In the raw material mixture preparation step, in addition to mixing 5.5 g of the infrared absorbing particles with the surface modification of the dispersant obtained in the dispersant reduction step and 30 g of styrene as the raw material of the coating resin, the organic phase was formed in the same manner as in Example 1. In addition, the infrared absorbing particles and other components are added and mixed in such a way that the content ratio (target ratio) of the infrared absorbing particles in the organic-inorganic hybrid infrared absorbing particles finally obtained in this Reference Example 1 becomes 10% by mass.

[0310] In addition to the above, the organic-inorganic hybrid infrared absorbing particles related to Reference Example 1 were obtained by operating in the same manner as in Example 1. From the dispersion liquid containing the obtained organic-inorganic hybrid infrared absorbing particles, the solvent was removed by vacuum flow to obtain the dry powder of the organic-inorganic hybrid infrared absorbing particles related to Reference Example 1. The obtained dry powder of the organic-inorganic hybrid infrared absorbing particles was mixed with a sheet-like soiling ink (best one medium manufactured by T&K TOKA Co., Ltd.) at a weight ratio of 2:30, and dispersed using a rotary mixer to obtain the composition for anti-counterfeiting ink related to Reference Example 1.

[0311] As the substrate to be printed, coated paper was used, and the above composition for anti-counterfeiting ink was printed on its surface to obtain an anti-counterfeiting printed matter including a printed film (printed portion).

[0312] In addition, in the stirring step, in the same manner as in Example 1, for the raw material mixture liquid prepared in the raw material mixture preparation step, in an ice bath, in the particle size distribution based on the scattering intensity measured by the dynamic light scattering method of the obtained microemulsion, stirring was performed until it became one peak. At this time, in the above particle size distribution of the microemulsion, D50 was 124 nm and the standard deviation was 96.

[0313] Table 2 shows the evaluation results.

[0314] [Comparative Example 1]

[0315] In the raw material mixture preparation step, in addition to mixing 135.2 g of the infrared absorbing particles with the surface modification of the dispersant obtained in the dispersion medium reduction step and 30 g of styrene as the raw material of the coating resin, the organic phase was formed in the same manner as in Example 1. In addition, the infrared absorbing particles and other components were added and mixed so that the content ratio (target ratio) of the infrared absorbing particles in the organic-inorganic hybrid infrared absorbing particles finally obtained in this Comparative Example 1 became 60% by mass. In addition, the addition ratio of each component when forming the aqueous phase was the value shown in Table 1.

[0316] In addition to the above, the organic-inorganic hybrid infrared absorbing particles and the anti-counterfeiting printed matter related to Comparative Example 1 were manufactured by operating in the same manner as in Example 1, and evaluation was performed.

[0317] In addition, in the stirring step, for the raw material mixture liquid prepared in the raw material mixture preparation step, in an ice bath, in the particle size distribution based on the scattering intensity measured by the dynamic light scattering method of the obtained microemulsion, a long-time stirring treatment was continuously performed so as to become one peak. However, two peaks remained in the particle size distribution based on the scattering intensity measured by the dynamic light scattering method, and D50 did not sufficiently decrease.

[0318] Observation of the product obtained after the polymerization process using TEM showed that the surface of the infrared absorption particles could not be coated with the resin for coating, and furthermore, the infrared absorption particles could not be disposed in the resin capsules. That is, the organic-inorganic hybrid infrared absorption particles could not be produced.

[0319] Table 2 shows the evaluation results.

[0320] [Table 1]

[0321]

[0322] [Table 2]

[0323]

[0324] [Evaluation]

[0325] Based on the results shown in Table 2, it was confirmed that in the anti-counterfeiting printed matters of Examples 1 to 13, the reflectance at a wavelength of 1000 nm before the chemical resistance test was less than 50%, and the difference in the reflectance at the same wavelength before and after the chemical resistance test was 1.3% or less. That is, it was confirmed that the anti-counterfeiting printed matters and the anti-counterfeiting ink compositions of Examples 1 to 13 had excellent infrared absorption characteristics and chemical resistance characteristics.

[0326] On the other hand, it was confirmed that the difference in the reflectance at a wavelength of 1000 nm before and after the chemical resistance test of the anti-counterfeiting printed matter of Reference Example 1 was 1.3% or less, which was excellent. However, when 10 sheets were printed, printing blur occurred, which was inferior to Examples 1 to 13. It was considered that this was because in Reference Example 1, the blending amount of the dry powder of the organic-inorganic hybrid infrared absorption particles in the anti-counterfeiting ink composition was larger than that in Example 1 and the like. Therefore, when printing, the anti-counterfeiting ink composition was not easily stretched.

[0327] This application claims priority based on Japanese Patent Application No. 2022-170551 filed with the Japan Patent Office on October 25, 2022, and incorporates the entire contents of Japanese Patent Application No. 2022-170551 into this international application.

[0328] Explanation of symbols

[0329] 20 Organic-inorganic hybrid infrared absorption particles

[0330] 21 Infrared absorption particles

[0331] 22 Resin for coating

[0332] 221 Resin capsule

[0333] 30 Anti-counterfeiting ink composition

[0334] 31 Organic-inorganic hybrid infrared absorption particles

[0335] 32 Liquid medium

Claims

1. A composition for forgery-proof ink, which comprises organic-inorganic hybrid infrared absorbing particles and a liquid medium, wherein the organic-inorganic hybrid infrared absorbing particles have infrared absorbing particles in an amount of 15% by mass or more and 55% by mass or less, and a coating resin covering at least a part of the surface of the infrared absorbing particles.

2. The composition for forgery-proof ink according to claim 1, wherein the coating resin contains one or more selected from the group consisting of polyester resin, polycarbonate resin, acrylic resin, polystyrene resin, polyamide resin, vinyl chloride resin, olefin resin, fluororesin, polyvinyl acetate resin, polyurethane resin, acrylonitrile-butadiene-styrene resin, polyvinyl acetal resin, acrylonitrile-styrene copolymer resin, ethylene-vinyl acetate copolymer resin, phenolic resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyimide resin, and silicone resin.

3. The composition for forgery-proof ink according to claim 1 or 2, The infrared absorbing particles contain at least one selected from tungsten oxides represented by the general formula W y O z and composite tungsten oxides represented by the general formula M x W y O z In the general formula W y O z , W is tungsten, O is oxygen, and 2.2 ≤ z / y ≤ 2.

999. In the general formula M x W y O z , the element M is at least one selected from H, He, Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Hf, Os, Bi, and I, 0.001 ≤ x / y ≤ 1, and 2.0 ≤ z / y < 4.

0.

4. A printed matter for forgery prevention, which has a printing portion containing the composition for forgery-proof ink according to claim 1 or 2.

5. The printed matter for forgery prevention according to claim 4, wherein the printing portion contains an organic binder.

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