JP2023151573A - Near-infrared curable ink composition, near-infrared cured film, and method for producing near-infrared cured product - Google Patents

Abstract

To provide a near-infrared curable ink composition which contains near-infrared absorption particles containing a composite tungsten oxide, and can be set to a more neutral color tone when it is cured.SOLUTION: A near-infrared curable ink composition contains a thermosetting resin or a thermoplastic resin, and near-infrared absorption particles, wherein the near-infrared absorption particles contain a cesium tungstate, the cesium tungstate has a pseudo hexagonal crystal structure modulated to one or more kinds selected from orthorhombic, rhombohedral and cubic crystals, the cesium tungstate is represented by general formula: CsxWyOz, in a ternary composition diagram with Cs, W and O as each apex, and it has a composition in an area surrounded by four straight lines of x=0.6y, z=2.5y, y=5x and Cs2O:WO3=m:n (m and n are integers).SELECTED DRAWING: Figure 1A

Description

The present invention relates to a near-infrared curable ink composition, a near-infrared cured film, and a method for producing a near-infrared cured product.

In recent years, ultraviolet curing paints that cure using ultraviolet light have become widely known as environmentally friendly paints, as described in Patent Documents 1 to 6, for example, because they can be printed without heating. It is being

However, when a composition that undergoes radical polymerization by ultraviolet irradiation is used as an ultraviolet curable ink or paint, the presence of oxygen inhibits polymerization (curing). On the other hand, when a composition that undergoes cationic polymerization by irradiation with ultraviolet rays is used, there is a problem in that strong acids are generated during the polymerization.

Furthermore, in order to improve the light resistance of the resulting printed or coated surface, an ultraviolet absorber is generally added to the printed or coated surface. However, when an ultraviolet absorber is added to an ultraviolet curable ink or paint, there is a problem in that curing by ultraviolet irradiation is inhibited.

In order to solve these problems, Patent Document 7 and Patent Document 8 propose near-infrared curable compositions that are cured by near-infrared ray irradiation instead of ultraviolet rays.

Furthermore, the applicant of the present application has disclosed near-infrared curable ink compositions containing composite tungsten oxide in Patent Documents 9 and 10.

Japanese Patent Application Publication No. 7-100433 Japanese Patent Application Publication No. 2001-146559 JP2009-057548A Japanese Patent Application Publication No. 2012-140516 Japanese Patent Application Publication No. 2000-037943 Japanese Patent Application Publication No. 2004-18716 Japanese Patent Application Publication No. 2008-214576 Japanese Patent Application Publication No. 2015-131928 International Publication No. 2017/047736 International Publication No. 2019/054478

K. Machida, M. Okada, and K. Adachi, "Excitations of free and localized electrons at nearby energies in reduced cesium tungsten bronze nanocrystals," Journal of Applied Physics, Vol. 125, 103103 (2019) S. Yoshio and K. Adachi, "Polarons in reduced cesium tungsten bronzes studied using the DFT+U method," Materials Research Express, Vol. 6, 026548 (2019) S. F. Solodovnikov, N.V. Ivannikova, Z.A. Solodovnikova, E.S. Zolotova, "Synthesis and X-ray diffraction study of potassium, rubidium, and cesium polytungstates with defect pyrochlore and hexagonal tungsten bronze structures," Inorganic Materials, Vol. 34, 845-853 (1998 ) S. Nakakura, A. F. Arif, K. Machida, K. Adachi, T. Ogi, Cationic defect engineering for controlling the infrared absorption of hexagonal cesium tungsten bronze nanoparticles, Inorg. Chem., 58, 9101-9107 (2019)

However, according to studies by the present inventors, the near-infrared curable compositions described in Patent Document 7 and Patent Document 8 mentioned above both had the problem of insufficient near-infrared absorption characteristics.

On the other hand, although the composite tungsten oxide fine particles contained in the near-infrared curable ink compositions disclosed in Patent Documents 9 and 10 have high visible light transmittance and low absorption rate, , is a material that has low transmittance and high absorption rate for light in the near-infrared region. Therefore, a near-infrared curable ink composition containing such composite tungsten oxide fine particles also has excellent near-infrared absorption characteristics.

However, composite tungsten oxide fine particles preferentially absorb long-wavelength light of visible light, that is, red light, so they are colored blue, and the degree of blue color becomes stronger as the amount of the fine particles added increases. Ta. For this reason, cured films obtained by containing composite tungsten oxide fine particles as a near-infrared absorbing component are colored blue, and the addition of other pigments may result in a yellow color that is a complementary color to blue or a light color other than blue. It was difficult to make it more colorful.

Therefore, an object of one aspect of the present invention is to provide a near-infrared curable ink composition that contains near-infrared absorbing particles containing a composite tungsten oxide and is capable of producing a more neutral color tone when cured. shall be.

In one aspect of the present invention, a thermosetting resin or a thermoplastic resin;
Near-infrared absorbing particles;
The near-infrared absorbing particles contain cesium tungstate,
The cesium tungstate has a pseudohexagonal crystal structure modulated into one or more types selected from orthorhombic, rhombohedral, and cubic,
The cesium tungstate is represented by the general formula Cs _x W _y O _z , and in the ternary composition diagram with Cs, W, and O as the vertices, x = 0.6y, z = 2.5y, y =5x, and a near-infrared curable ink composition having a composition within a region surrounded by four straight lines: Cs ₂ O: WO ₃ = m: n (m and n are integers).

According to one aspect of the present invention, it is possible to provide a near-infrared curable ink composition that contains near-infrared absorbing particles containing a composite tungsten oxide and can be cured to provide a more neutral color tone.

FIG. 1A is a Cs-WO composition diagram with Cs, W, and O as vertices. FIG. 1B is an enlarged view of a part of the Cs-WO composition diagram with Cs, W, and O as the vertices. FIG. 2 shows powder XRD diffraction patterns of near-infrared absorbing particles produced in Examples 1 to 6 and Comparative Examples 1 and 2. FIG. 3 shows powder XRD diffraction patterns of near-infrared absorbing particles produced in Examples 9 to 14. FIG. 4 shows a transmission electron microscope bright field image, a selected area electron diffraction image, and a high angle scattering dark field (HAADF) image of the near-infrared absorbing particles produced in Example 1. FIG. 5 is an explanatory diagram of near-infrared absorbing particles having a coating. FIG. 6 is an explanatory diagram of a near-infrared curable ink composition.

Hereinafter, modes for carrying out the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments, and the following embodiments may be implemented without departing from the scope of the present invention. Various modifications and substitutions can be made to .
[Near-infrared curable ink composition]
Regarding the near-infrared curable ink composition, near-infrared cured film, and near-infrared cured product production method according to the present embodiment, [1] near-infrared absorbing particles, [2] method for producing near-infrared absorbing particles, [3] near-infrared absorbing particles, Infrared absorbing particle dispersion, [4] Near infrared curable ink composition, [5] Method for producing near infrared curable ink composition, [6] Near infrared cured film, method for producing near infrared cured film, [7] The method for producing a near-infrared cured product will be explained in order.
[1] Near-infrared absorbing particles As described below, the near-infrared curable ink composition of this embodiment contains near-infrared absorbing particles. Therefore, near-infrared absorbing particles will be explained first.

The near-infrared absorbing particles contain cesium tungstate, which is a composite tungsten oxide. Note that the near-infrared absorbing particles of this embodiment can also be composed of cesium tungstate. However, even in this case, the inclusion of unavoidable impurities is not excluded.
(1) About cesium tungstate Cesium tungstate (cesium polytungstate) has a quasi-hexagonal crystal structure modulated into one or more types selected from orthorhombic, rhombohedral, and cubic. I can do it. Specifically, the cesium tungstate has one or more types of crystal structures selected from orthorhombic, rhombohedral, and cubic, which are modified pseudo-hexagonal structures that are partially modified from hexagonal alkali tungsten bronze structures. can have

The transmitted color and light absorption of cesium-doped hexagonal tungsten bronze particles, which have been conventionally used as near-infrared absorption particles, are defined by the imaginary part of the dielectric function (ε ₂ ) and the band structure.

In the energy range of visible light (1.6 eV to 3.3 eV), cesium-doped hexagonal tungsten bronze (hereinafter also referred to as Cs-HTB) has a sufficiently large band gap, and the absorption of light in the visible light range is Basically suppressed. In addition, electronic transition between the dd orbits of tungsten and the pp orbital of oxygen is prohibited by the Fermi golden rule, so that the probability of electronic transition becomes small. Due to these two effects, ε ₂ takes a small value at wavelengths in the visible light region. Since ε ₂ represents the absorption of photons by electrons, if ε ₂ is small in wavelength in the visible light region, visible light transparency occurs. However, near the blue wavelength, which is the shortest wavelength in the visible light region, there is absorption due to band edge transition, and near the red wavelength, which is the longest wavelength, there is localized surface plasmon resonance (LSPR) absorption and polaronic electronic transition absorption. It has recently been revealed that there exists (Non-Patent Document 1). For this reason, each is subject to restrictions on light transmittance.

As mentioned above, in Cs-HTB, the band gap is sufficiently large, so that the band edge transition exceeds the energy of blue wavelength light, resulting in blue transparency. On the other hand, on the red wavelength side, Cs-HTB has a large number of conduction electrons, so LSPR absorption and polaronic absorption become strong, and the base of this absorption extends to the red wavelength, resulting in low red transparency. Therefore, the transmitted color of the Cs-HTB nanoparticle dispersed film appears blue due to the balance between the two.

That is, in order to neutralize the blue transmitted color of Cs-HTB, it is sufficient to strengthen the absorption on the blue side and the transmission on the red side.

Increasing the absorption on the blue side of Cs-HTB can be achieved, for example, by shifting the absorption position of band edge transition to the lower energy side. Shifting the absorption position of the band edge transition to the lower energy side corresponds to narrowing the band gap of Cs-HTB. Therefore, it can be realized by selecting a material with a rather small band gap.

Weakening the red side absorption of Cs-HTB can be achieved by lowering the concentration of surface plasmon resonance electrons and the concentration of polaron bound electrons.

Based on the above considerations, the inventors of the present invention conducted various studies on cesium tungsten oxide, which is an oxide containing cesium (Cs) and tungsten (W), and also used band structure calculations based on first-principles calculations. At the same time, we continued to improve materials. As a result, when the conventional hexagonal crystal structure changes to a quasi-hexagonal structure modulated to orthorhombic, rhombohedral, or cubic due to changes in the microstructure, the band structure changes and free electrons and They discovered that the amount of bound electrons changes, resulting in a change in color.

Here, a quasi-hexagonal structure modulated into one or more types selected from orthorhombic, rhombohedral, and cubic crystals means that Cs-rich surfaces are arranged regularly or randomly on the prism surface or bottom surface of the hexagonal crystal. It means a quasi-hexagonal crystal that is inserted into and modulated. Note that the Cs-rich surface is synonymous with a W- and O-deficient surface. In addition, as described later, O, OH, OH ₂ and OH ₃ ions can be substituted into the Cs site, and the introduction of these ions to the prism surface or bottom surface promotes modulation to the quasi-hexagonal structure in the same way as Cs. I can do it.

Orthorhombic, rhombohedral, and cubic crystal structures can be identified, for example, by electron diffraction. For example, they can be distinguished by paying attention to the symmetry of the diffraction spot when the c-axis direction is the electron beam incident direction, that is, when the electron beam is incident from the (0001) direction and observed.

In a hexagonal system, the diffraction spots of three types of prism surfaces (10-10), (01-10), and (1-100) appear at the same distance from the incident spot within the reciprocal lattice plane. In other words, hexagonal crystals have the same crystal plane spacing. Note that the above-mentioned same distance includes distances that can be considered to be the same distance within the error range of electron diffraction spot distance measurement. Therefore, the hexagonal crystal has a hexagonal symmetrical electron diffraction pattern, that is, an electron diffraction pattern that does not change even when rotated by 60°.

In the orthorhombic crystal, one type of prism surface spot appears at a position closer to the incident spot than the other two types of prism surface spots. That is, in the orthorhombic crystal, only one type of prism face has a long crystal face spacing.

In the rhombohedral crystal, three types of prism surface spots have different crystal plane spacings.

The cubic crystal has the same hexagonal symmetry pattern as the hexagonal crystal, but the cubic symmetry can be easily identified by observation from other crystal zone axis directions.

In XRD powder patterns, pseudohexagonal crystals are often regarded as mixed patterns of orthorhombic crystals and hexagonal crystals, rhombohedral crystals and hexagonal crystals, or cubic crystals and hexagonal crystals, but the above-mentioned planar lattice Due to the insertion of defects, the position and intensity of the diffraction peaks change slightly.

As one of the methods for obtaining a pseudohexagonal crystal structure modulated into one or more types selected from the above-mentioned orthorhombic, rhombohedral, and cubic crystals, a crystal structure selected from O, OH, _OH2 , and _OH3 is used. Examples include a method of adding one or more types of additive components. Therefore, in the near-infrared absorbing particles of this embodiment, it is preferable that the cesium tungstate contains one or more types of additive components selected from O, OH, _OH2 , and _OH3 .

The one or more additive components selected from O, OH, _OH2 , and _OH3 mentioned above are formed by six WO ₆ octahedrons constituting the hexagonal alkali tungsten bronze structure of the cesium tungstate crystal. 1 selected from a hexagonal window existing in a hexagonal tunnel penetrating in the c-axis direction of the hexagon, and a hexagonal cavity, and a triangular three-sided cavity formed by three of the WO ₆ octahedra. It is preferable to exist in more than one type of position.

There are two cavities in the hexagonal tunnel: the hexagonal cavity, which is large in size, and the hexagonal window.The hexagonal window is the second largest after the hexagonal cavity in the hexagonal crystal, and is surrounded by six oxygen atoms that make up the WO ₆ octahedron. It is a void that has been removed. The upper and lower sides of the hexagonal window in the c-axis direction are adjacent to the Cs ions arranged in the hexagonal cavity. The three-sided cavity is the next largest cavity after the hexagonal window, and penetrates the hexagonal crystal in the c-axis direction. One or more selected from O, OH, _OH2 , and _OH3 can replace Cs and enter the hexagonal cavity, but if there is a sufficient amount of Cs or there is a large amount of moisture entering, the hexagonal window to invade. In some cases, it invades the three-sided cavity on the bottom or the cavity on the prism surface in parallel with the hexagonal window gap, and also replaces Cs. Inclusion of the above additive components produces defective surfaces on the bottom and prism surfaces, but at that time, the crystal structure shifts from hexagonal to orthorhombic, rhombohedral, and then cubic, narrowing the band gap. and a decrease in the conduction band electron concentration occurs. Therefore, compared to Cs-HTB, cesium tungstate, which has a quasi-hexagonal crystal structure, can strengthen absorption on the blue side and transmission on the red side, making the transmitted blue color neutral. can be converted into

The orthorhombic, rhombohedral, and cubic crystals in this case can also be viewed as pseudohexagonal crystals that have an atomic arrangement similar to that of tungsten bronze hexagonal crystals, but have a different symmetry from hexagonal crystals. To avoid strictness and describe it roughly, this case breaks the hexagonal symmetry by regularly or randomly inserting W and O deficient surfaces into one of the three types of hexagonal prism surfaces. It is an orthorhombic crystal. Therefore, in the orthorhombic crystal, only one prism face has a long interplanar spacing. Utilizing this, modulation to orthorhombic crystal can be easily identified by, for example, a (0001) electron diffraction pattern.

In this case, a rhombus is created by inserting a surface that accepts excess Cs into the base of the hexagonal crystal, that is, a surface lacking W and O, and regularly displacing the stacked layers in the c-axis direction on the base to break the hexagonal symmetry. It is a hedral crystal. In this case, the surplus Cs surface includes displacement on the surface as well as expansion in the direction perpendicular to the surface, and therefore is accompanied by a change in the prism surface spacing and a change in the c-axis lattice constant. Therefore, in a rhombohedral crystal, all three prism surfaces have different interplanar spacings. Utilizing this, modulation to rhombohedral crystals can be easily identified by, for example, a (0001) electron diffraction pattern.

Furthermore, when the three axes of a rhombohedron intersect at 90 degrees, it becomes a cubic crystal. Note that the cubic crystal has a pyrochlore structure, and a typical composition thereof is CsW ₂ O ₆ .

Therefore, the voids corresponding to the hexagonal windows, hexagonal cavities, and trigonal cavities described above are also carried over to orthorhombic, rhombohedral, and cubic crystals. Therefore, the hexagonal windows, hexagonal cavities, and trigonal cavities in the cesium tungstate contained in the near-infrared absorbing particles of this embodiment are the same as those in the orthorhombic, rhombohedral, and cubic crystals (pyrochlore phase). This includes voids.

Hereinafter, an example of the structure of the method for producing near-infrared absorbing particles of this embodiment will be explained, mainly using a hexagonal window as an example of a site or void where O, OH, OH ₂ , and OH ₃ can be substituted or invaded.

One of the methods for obtaining orthorhombic, rhombohedral, and cubic crystals in which one or more types selected from O, OH, _OH2 , and _OH3 are present in the hexagonal window is the crystal used when synthesizing cesium tungstate. An example of this method is to crystallize in saturated steam during crystallization. Generally, in a Cs-HTB structure, the ionic radius of Cs is slightly larger than that of a hexagonal cavity, so Cs is difficult to move. Therefore, once crystallized into hexagonal crystals, it becomes difficult to diffuse and insert oxygen atoms into the hexagonal windows during subsequent heat treatment or the like. Therefore, before the cesium tungstate crystallizes, the atmosphere is filled with saturated water vapor, and at the same time as the cesium tungstate crystallizes, water molecules and O, OH, and _OH3 ions derived from the water molecules are released in all directions. I devised a method to insert it into a window. Therefore, as will be described later, the method for producing near-infrared absorbing particles of the present embodiment includes a step of introducing water vapor at a heating temperature near the crystallization temperature of cesium tungstate and crystallizing it in an atmosphere containing water vapor. It is preferable. When near-infrared absorbing fibers are produced using the near-infrared absorbing particles synthesized through the above steps and the near-infrared absorbing particles further heat-treated in a reducing atmosphere if necessary, while the near-infrared absorbing effect is sufficiently maintained, It is possible to reduce the blueness from the color tone. In other words, a neutral color tone can be achieved.

On the other hand, once a hexagonal crystal of cesium tungstate is produced, even if the cesium tungstate is heated in a steam atmosphere or held and heated in a high temperature and high humidity environment, the above-mentioned transmission color will be neutralized. No sexualizing effect can be obtained. This is because an element with a large ionic radius such as Cs inhibits the diffusion of oxygen atoms etc. through hexagonal tunnels, so once it is crystallized into a hexagonal crystal, it is difficult for oxygen atoms to fit into the hexagonal window of the void during subsequent heat treatment. This is because they cannot be spread. Therefore, the heat treatment in steam needs to be performed during the first crystallization during synthesis.

When heating in an atmosphere containing water vapor during crystallization, it is also possible to simultaneously mix a reducing gas such as hydrogen gas and perform crystallization in the reducing gas atmosphere. In addition, if the crystal has been crystallized in a steam atmosphere, it can be further heated at a high temperature of 500°C to 950°C in an atmosphere containing reducing gases such as hydrogen gas, or in an inert gas atmosphere. It is also possible to perform processing. In either case, it is possible to obtain near-infrared absorbing particles whose transmitted color is neutralized and which has a large near-infrared absorption effect. By setting the temperature to 500° C. or higher, the alignment of atoms to equilibrium atomic positions such as an orthorhombic structure including defects sufficiently progresses, and the near-infrared absorption effect is enhanced. Further, by setting the temperature to 950° C. or lower, the speed of crystal structure change can be maintained appropriately, and the crystalline state and electronic state can be easily controlled to be appropriate. It should be noted that if the heating temperature is set higher than 950° C. and the reduction is excessive, for example, lower oxides such as W metal and WO ₂ may be generated, which is not preferable from this point of view.

Selected from orthorhombic, rhombohedral, and cubic (pyrochlore phases) that are microscopically modified from hexagonal by the incorporation of O, OH, _OH2 , and _OH3 during crystallization by initial steam heating. One or more types of crystals are formed. By heat-treating these in atmospheres with different degrees of reduction, one or more types of crystal structures selected from orthorhombic, rhombohedral, and cubic crystals with different amounts and distributions of lattice defects are generated. It is.

The cesium tungstate contained in the near-infrared absorbing particles of this embodiment can have Cs, W, and O lattice defects. The reason why lattice defects of Cs, W, and O are introduced into cesium tungstate will be explained below.

At a composition near hexagonal Cs _0.33 WO ₃ , crystal stability is due to structural stability derived from high crystal symmetry and charge exchange between each element, which results in overall charge neutrality. The stability of the charge balance produced is competitively determined. For example, the charge-neutral 2Cs ₂ O.11WO ₃ =Cs ₄ W ₁₁ O ₃₅ is considered to be a thermodynamically stable phase, but when heated in a reducing atmosphere, it easily transforms into a hexagonal Cs _0.32 WO _3- with high crystal symmetry. The phase changes to _y (Non-patent Document 2). Cs _0.32 WO _3-y has a metastable structure with high crystal symmetry, while Cs ₄ W ₁₁ O ₃₅ has a stable composition in terms of charge balance. However, Cs ₄ W ₁₁ O ₃₅ has poor symmetry in the atomic arrangement within the crystal. For example, in the model of Solodovnikov (Non-Patent Document 3), in the hexagonal arrangement of WO ₆ octahedrons, which is the same as that of hexagonal tungsten bronze, A plane lacking W and O is inserted into the hexagonal (1,1,-2,0) plane (=orthorhombic (010) plane) at b/8 pitch of the orthorhombic unit cell, and the overall result is It is orthorhombic. In other words, Cs, W, and O defects are inevitably introduced to locally satisfy both crystal structure and charge balance, and have recently been observed using TEM and XRD (non-patent Reference 4).

In the near-infrared absorbing particles of this embodiment, O, OH, OH ₂ , and OH ₃ are localized in orthorhombic, rhombohedral, and cubic crystals that are incorporated into hexagonal windows, hexagonal cavities, and trigonal cavities. Due to the disturbed charge balance, the crystal microstructure is further modified. In other words, in the process of introducing components derived from water, H ⁺ and H ₃ O ⁺ are introduced into the crystal, but these ions compete with Cs ⁺ and W ⁶⁺ in the crystal, resulting in Cs and W vacancies. By doing so, we aim to achieve local charge neutrality. As a result, lattice defects including Cs and W defects are introduced. O, OH, OH ₂ and OH ₃ may enter not only the hexagonal window but also the three-sided cavity. Furthermore, OH ₂ and OH ₃ may be substituted with an alkali element (Cs) in a hexagonal cavity, and when OH ₂ with a neutral charge is substituted, the electrons emitted by the originally existing alkali ions (Cs ⁺ ) disappear. Therefore, the conduction band electrons of the crystal decrease.

Among cesium tungstates, which have a quasi-hexagonal crystal structure modulated into one or more types selected from orthorhombic, rhombohedral, and cubic crystals, it has excellent near-infrared absorption effect and visible light transmittance. A substance that satisfies the following has a predetermined composition.

Here, FIG. 1A shows a ternary composition diagram 10 with Cs-WO as three vertices. FIG. 1B is an enlarged view of a region 11 having CsWO ₃ , W ₂ O ₃ , and WO ₄ as vertices in the ternary composition diagram 10 of FIG. 1A. It should be noted that this diagram is not a phase diagram showing a thermodynamic equilibrium phase, but a convenient composition diagram to show the spread of the composition of this system. Therefore, CsWO ₃ , W ₂ O ₃ , WO ₄ , etc. are compositions shown for convenience, and do not refer to whether these are compounds that can actually be obtained.

The cesium tungstate contained in the near-infrared absorbing particles of this embodiment is represented by the general formula Cs _x W _y O _z , and in the ternary composition diagram with Cs, W, and O as the vertices, It is preferable to have a composition within a region surrounded by four straight lines: .6y, z=2.5y, y=5x, and Cs ₂ O:WO ₃ =m:n (m and n are integers). Specifically, among the ternary composition diagrams shown in FIGS. 1A and 1B, straight line 12 satisfies x = 0.6y, straight line 13 satisfies z = 2.5y, and straight line 13 satisfies y = 5x. The composition is preferably within a region 16 surrounded by a straight line 14 and a straight line 15 satisfying Cs ₂ O:WO ₃ =m:n (m and n are integers). Note that the region 16 also includes points on the straight lines 12 to 15. In addition, as shown in FIG. 1A, the straight line 15 that satisfies Cs ₂ O: WO ₃ = m: n (m and n are integers) is the line between Cs ₂ O and WO ₃ in the ternary composition diagram 10. It is a straight line that connects the two.

In the above ternary composition diagram, when x>0.6y, cesium tungstate has a crystal structure mainly composed of tetragonal crystals, and the near-infrared absorption effect disappears. In addition, when z<2.5y, lower oxides of W are mixed in the hexagonal crystal-based structure of cesium tungstate, and the near-infrared absorption effect and visible light transmittance are significantly impaired. . When y>5x, cesium tungstate has a crystal structure called intergrowth in which WO ₃ is mixed in a hexagonal substructure, and the near-infrared absorption effect disappears. Further, when Cs ₂ O:WO ₃ enters the O-rich side on the right side of the straight line 15 where the ratio is an integer, no near-infrared absorption effect is obtained. Therefore, it is preferable that the cesium tungstate satisfies the above-mentioned range.

The cesium tungstate contained in the near-infrared absorbing particles of this embodiment may have defects in each element of cesium, tungsten, and oxygen, but the atomic ratio of cesium to tungsten (x/y) is 0.2 or more. It can be in any range of 0.6 or less. That is, the near-infrared absorbing particles of this embodiment have defects in a part of one or more elements selected from Cs and W constituting the crystal of cesium tungstate, and have a general formula of Cs _x W _y O _z . It is preferable that x and y have a relationship of 0.2≦x/y≦0.6.

Since cesium and tungsten supply electrons to the crystal, by setting x/y to 0.2 or more, the near-infrared absorption function can be enhanced. Furthermore, by setting x/y to 0.2 or more, a hexagonal crystal structure or a crystal structure in which the hexagonal crystal structure is modulated can be obtained. When the x/y ratio exceeds 0.33, Cs ions cannot fit into the hexagonal cavity and begin to occupy the three-sided cavity, causing modulation on the prism surface and bottom surface, so that the Cs ion gradually becomes orthorhombic or orthorhombic. It changes to a laminated structure of rhombohedral or cubic pyrochlore. Further, when x/y exceeds 0.6, the crystal structure changes to a tetragonal Cs ₂ W ₃ O ₁₀ , and the visible light transmittance is significantly impaired, resulting in a decrease in usefulness.

The near-infrared absorbing particles of this embodiment can have a defect in at least a part of W of the WO ₆ octahedron forming the crystal, based on the hexagonal cesium tungsten bronze structure Cs _0.33 WO ₃ . This W defect is mainly introduced as a planar defect on the hexagonal prism surface or bottom surface, but the crystal symmetry changes from hexagonal to orthorhombic because the ion repulsion of the atomic arrays on both sides of the defect plane increases the interplanar spacing. It changes to crystal, rhombohedral, and cubic crystals.

The near-infrared absorbing particles of this embodiment can have a defect in at least a part of O of the WO ₆ octahedron that constitutes the crystal of cesium tungstate, based on the hexagonal alkali tungsten bronze structure CsW ₃ O ₉ . . These O vacancies are randomly introduced, and by vacating them, localized electrons can be supplied to the system and the near-infrared absorption function can be enhanced. In the known hexagonal tungsten bronze Cs _0.32 WO _3-y , it is known that y=0.46 or a maximum of 15% of all O lattice points constituting an octahedron (Non-patent Document 3) . When the amount of defects exceeds 0.5, the crystal becomes unstable, generates different phases, and decomposes. The cesium tungstate Cs _x W _y O _z contained in the near-infrared absorbing particles of this embodiment can contain an amount of O vacancies corresponding to a maximum of z/y=2.5. However, when excess O, OH, OH ₂ , and OH ₃ are introduced into voids such as hexagonal windows, it must be noted that the identified value of O obtained by chemical analysis includes these surpluses.

In the cesium tungstate contained in the near-infrared absorbing particles of this embodiment, a part of Cs may be replaced with an additive element. In this case, the additive element is preferably one or more selected from Na, Tl, In, Li, Be, Mg, Ca, Sr, Ba, Al, and Ga.

These additional elements have electron-donating properties and assist in donating electrons to the conduction band of the WO octahedral skeleton at the Cs site.
(2) Regarding heat-and-moisture resistance of near-infrared absorbing particles The near-infrared absorbing particles of this embodiment exhibit improved heat-and-moisture resistance compared to cesium-doped hexagonal tungsten bronze. This effect is due to the fact that some of the near-infrared absorbing particles of this embodiment are selected from orthorhombic, rhombohedral, and cubic (pyrochlore phases) modulated by interstitial substitution of O, OH, _OH2 , and _OH3 . This is a reasonable result considering that more than one type is included. In other words, the humidity and moisture deterioration of cesium-doped hexagonal tungsten bronze is essentially a substitution reaction between Cs and water molecules, but the cavities and windows of the hexagonal tunnel, which is the main diffusion route for oxygen diffusion, are also affected by Cs, O, If filled with OH, _OH2 , _OH3 , this substitution reaction will be greatly slowed down. Therefore, the near-infrared absorbing particles of this embodiment not only suppress the loss of near-infrared absorbing function in a high-humidity environment, but also slow down the deterioration reaction mediated by atmospheric moisture in a high-temperature heat resistance test at normal humidity. This results in improved heat and humidity resistance.
(3) Regarding the average particle size of the near-infrared absorbing particles The average particle size of the near-infrared absorbing particles of this embodiment is not particularly limited, but is preferably 0.1 nm or more and 200 nm or less. This is because by setting the average particle size of near-infrared absorbing particles to 200 nm or less, localized surface plasmon resonance is more prominently expressed, so near-infrared absorption characteristics can be particularly enhanced, that is, solar transmittance can be particularly improved. This is because it can be suppressed. Moreover, by setting the average particle size of the near-infrared absorbing particles to 0.1 nm or more, it is possible to easily manufacture the near-infrared absorbing particles industrially. In addition, the particle size is closely related to the color of the near-infrared curable ink composition and near-infrared cured film, and in the particle size range where Mie scattering is dominant, the smaller the particle size, the more the short wavelength in the visible light region. Scatter is reduced. Therefore, increasing the particle size has the effect of suppressing the blue tone, but when the average particle size exceeds 200 nm, the generation of surface plasmon is suppressed and LSPR absorption becomes small. Therefore, by setting the average particle size of the near-infrared absorbing particles to 200 nm or less, it is possible to maintain a certain level of LSPR absorption while making the color of the near-infrared curable ink composition and near-infrared cured film particularly neutral. .

Here, the average particle size of the near-infrared absorbing particles is measured by the median diameter of multiple near-infrared absorbing particles measured from a transmission electron microscope image, or by a particle size measuring device based on the dynamic light scattering method of a dispersion liquid. This can be determined from the dispersed particle size.

In addition, when applying to applications where transparency in the visible light region is particularly important, it is preferable to further consider reducing scattering by near-infrared absorbing particles. When emphasis is placed on reducing scattering, it is particularly preferable that the average particle size of the near-infrared absorbing particles is 30 nm or less.

The average particle size means the particle size at 50% of the integrated value in the particle size distribution, and the average particle size has the same meaning in other parts of this specification. As a method for measuring the particle size distribution for calculating the average particle size, for example, direct measurement of the particle size of each particle using a transmission electron microscope can be used. Further, the average particle size can also be measured using a particle size measuring device based on a dynamic light scattering method of a dispersion liquid as described above.
(4) Arbitrary configuration of near-infrared absorbing particles Near-infrared absorbing particles can also be subjected to surface treatment for the purpose of surface protection, improving durability, preventing oxidation, improving water resistance, etc. Although the specific content of the surface treatment is not particularly limited, for example, as shown in FIG. 5, the near-infrared absorbing particles of this embodiment may have a coating 51 on the surface 50A of the near-infrared absorbing particles 50. can. Specifically, the surface of the near-infrared absorbing particles 50 can be coated with a coating 51 of a compound containing one or more types of atoms selected from Si, Ti, Zr, Al, and Zn. That is, the near-infrared absorbing particles can be coated with the above compound. In this case, the compound containing one or more types of atoms selected from Si, Ti, Zr, Al, and Zn includes one or more types selected from oxides, nitrides, carbides, and the like.

Note that FIG. 5 only schematically shows the form of near-infrared absorbing particles, and is not limited to this form. For example, the near-infrared absorbing particles 50 may have an amorphous shape instead of a spherical shape. The coating 51 does not need to completely cover the surface 50A of the near-infrared absorbing particles 50, and may be arranged so as to cover only a portion thereof. Furthermore, the thickness of the coating 51 may vary depending on the location on the surface 50A of the near-infrared absorbing particles 50.
[2] Method for manufacturing near-infrared absorbing particles Next, a configuration example of a method for manufacturing near-infrared absorbing particles according to the present embodiment will be described. According to the method for producing near-infrared absorbing particles of this embodiment, the above-mentioned near-infrared absorbing particles can be produced, so a portion of the explanation will be omitted.

The method for producing near-infrared absorbing particles is not particularly limited, and any method that can produce near-infrared absorbing particles that satisfy the above-mentioned characteristics can be used without particular limitation. Here, a configuration example of a method for producing near-infrared absorbing particles will be described.
(1) First heat treatment step The method for producing near-infrared absorbing particles of this embodiment can include, for example, the following steps.

A first heat treatment step of heating a compound raw material containing Cs and W at a temperature of 400° C. or more and 650° C. or less in an atmosphere containing water vapor or an atmosphere containing water vapor and a reducing gas.

In the first heat treatment step, cesium tungstate can be crystallized by heating at 400° C. or higher and 650° C. or lower.

However, in order to make cesium tungstate into a pseudo-hexagonal crystal, it is preferable to contain sufficient water vapor in the atmosphere when the cesium tungstate crystallizes, that is, when the WO ₆ unit forms a hexagonal crystal with Cs. . In this crystallization process, Cs is mainly incorporated into the hexagonal cavity, and water molecules or their decomposition products, OH ₃ ⁺ , OH ⁻ and O ²⁻ are mainly incorporated into the hexagonal window. When there is a relatively large amount of Cs or water molecules in the composition, Cs or water molecules are also incorporated into the three-sided cavity.

As the compound raw material containing Cs and W, a mixture of a compound raw material containing Cs and a compound raw material containing W can be used. As the compound raw material containing Cs and W, any material containing Cs and W is sufficient, and for example, a mixture of Cs ₂ CO ₃ and WO ₃ can be used.

However, in the crystallization process of the first heat treatment step, the purpose is to incorporate water molecules, OH, O, etc. into the crystal during crystallization. Therefore, as a raw material for a compound containing Cs and W, cesium tungsten oxide that has already formed a hexagonal structure, such as nCs ₂ O・mWO ₃ (n and m are integers, 3.6≦m/n≦9 .0) is preferably not used. Examples of raw materials for compounds containing Cs and W include cesium tungstate obtained by other methods such as sol-gel method and complex polymerization method, non-equilibrium cesium tungstate obtained by vapor phase synthesis, and powder obtained by thermal plasma method. It is also preferable not to use powder obtained by melting a powder or an electron beam as a raw material. This is because in raw materials that have already formed a hexagonal skeleton structure, Cs inhibits the diffusion of oxygen atoms and the like, making it difficult for water molecules and the like to be incorporated into the crystal. That is, it is preferable that cesium tungstate having a hexagonal crystal structure is not used as a compound raw material containing Cs and W.

The supply of steam in the crystallization process of the first heat treatment step is preferably realized by supplying superheated steam into a heating furnace, for example. Superheated steam is high enthalpy steam that is made by adding heat to saturated steam vaporized at 100° C. to a high temperature of 100° C. or higher, and may be supplied together with a carrier gas. When the carrier gas is an inert gas, an atmosphere close to oxygen-free is formed. Superheated steam may be supplied at a temperature of 400° C. or higher, where crystallization becomes active, but it is preferably supplied at a sufficiently low temperature before crystallization. A mixed gas of superheated steam and an inert gas, or a mixed gas of superheated steam, an inert gas, and a reducing gas such as hydrogen may be supplied. When a reducing gas is mixed, the rate of hexagonal crystal alignment tends to increase, and even the same orthorhombic, rhombohedral, or cubic crystals may have different microscopic defect structures. be.

In the first heat treatment step, heating may be performed in an atmosphere that does not contain water vapor, such as an inert atmosphere, before or after crystallization of the cesium tungstate.

The method for producing near-infrared absorbing particles of the present embodiment can further include an arbitrary step.
(2) Second heat treatment step The method for producing near-infrared absorbing particles of this embodiment includes, after the first heat treatment step, a second heat treatment step of heating at a temperature of 500°C or higher and 950°C or lower in an atmosphere containing a reducing gas. It is also possible to have

The second heat treatment step is a step in which, for example, the material powder that has undergone the first heat treatment step is heated and reduced at a temperature of 500° C. or higher and 950° C. or lower. In addition to annealing and stabilizing orthorhombic, rhombohedral, and cubic crystals with defect structures, it is also meaningful to remove part of the oxygen in the WO ₆ octahedron by high-temperature reduction. Reductive removal of octahedral oxygen generates bound electrons in adjacent W atoms, resulting in a structural treatment that enhances near-infrared absorption properties.

When performing the thermal reduction treatment, it is preferable to perform it under a stream of reducing gas. As the reducing gas, a mixed gas containing a reducing gas such as hydrogen and one or more types of inert gases selected from nitrogen, argon, etc. can be used. Further, heating in a steam atmosphere or vacuum atmosphere or other mild heating and reducing conditions may be used in combination.

The second heat treatment step can be comprised of multiple steps, and after heating in the reducing gas atmosphere, heating can be further performed in an inert gas atmosphere.

In addition, in the second heat treatment step, if part of the oxygen in the WO ₆ octahedron is not intended to be removed, heating may be performed in an inert gas atmosphere in the above temperature range instead of an atmosphere containing a reducing gas. can. That is, the second heat treatment step can be performed at a temperature of 500° C. or more and 950° C. or less in an atmosphere containing a reducing gas or an inert gas atmosphere.

As mentioned above, the method for producing the near-infrared absorbing particles of this embodiment is not particularly limited. As a method for producing near-infrared absorbing particles, various methods can be used that can produce a predetermined structure including a defect microstructure.

As a method for producing near-infrared absorbing particles, a method of synthesizing tungstate by a solid phase method, a liquid phase method, or a gas phase method in an atmosphere where water molecules coexist may be used.
(3) Grinding Step As mentioned above, the near-infrared absorbing particles are preferably finely divided into fine particles. Therefore, the method for producing near-infrared absorbing particles can also include a pulverizing step of pulverizing the powder obtained in the first heat treatment step and the second heat treatment step.

The specific means for pulverizing and refining is not particularly limited, and various means capable of mechanically pulverizing can be used. As the mechanical pulverization method, a dry pulverization method using a jet mill or the like can be used. In addition, in the process of obtaining a near-infrared absorbing particle dispersion, which will be described later, it may be mechanically pulverized in a solvent.

If necessary, further sieving etc. can be performed.
(4) Coating step As described above, the surface of the near-infrared absorbing particles may be coated with a compound containing one or more types of atoms selected from Si, Ti, Zr, Al, and Zn. Therefore, the method for producing near-infrared absorbing particles may further include, for example, a coating step of coating the near-infrared absorbing particles with a compound containing one or more types of atoms selected from Si, Ti, Zr, Al, and Zn. .

In the coating step, the specific conditions for coating the surface of the near-infrared absorbing particles are not particularly limited. For example, it is possible to include a coating step in which an alkoxide containing one or more metals selected from the above metal group is added to the near-infrared absorbing particles to be coated, and the surface of the near-infrared absorbing particles is coated.
[3] Near-infrared absorbing particle dispersion Next, a configuration example of the near-infrared absorbing particle dispersion of this embodiment will be described.

The near-infrared absorbing particle dispersion liquid of this embodiment can also be used, for example, when manufacturing a near-infrared curable ink composition described below.

The near-infrared absorbing particle dispersion liquid of the present embodiment includes the above-described near-infrared absorbing particles and a liquid medium of one or more types selected from water, organic solvents, oils and fats, liquid resins, and liquid plasticizers. I can do it. The near-infrared absorbing particle dispersion preferably has a structure in which near-infrared absorbing particles are dispersed in a liquid medium.

As the liquid medium, one or more selected from water, organic solvents, oils and fats, liquid resins, and liquid plasticizers can be used as described above.

As the organic solvent, various solvents can be selected, such as alcohols, ketones, esters, hydrocarbons, and glycols. Specifically, alcoholic solvents such as isopropyl alcohol, methanol, ethanol, 1-propanol, isopropanol, butanol, pentanol, benzyl alcohol, diacetone alcohol, and 1-methoxy-2-propanol; dimethyl ketone, acetone, methyl ethyl ketone, Ketone solvents such as methyl propyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone; Ester solvents such as 3-methyl-methoxy-propione and butyl acetate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl Glycol derivatives such as ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate; formamide, N-methylformamide, dimethylformamide, dimethylacetamide, N -Amides such as methyl-2-pyrrolidone; aromatic hydrocarbons such as toluene and xylene; and halogenated hydrocarbons such as ethylene chloride and chlorobenzene.

However, among these, organic solvents with low polarity are preferred, and in particular, isopropyl alcohol, ethanol, 1-methoxy-2-propanol, dimethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, toluene, propylene glycol monomethyl ether acetate, acetic acid n- Butyl and the like are more preferred. These organic solvents can be used alone or in combination of two or more.

Examples of oils and fats 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. , fatty acid monoesters obtained by direct ester reaction of vegetable oil fatty acids and monoalcohols, ethers, Isopar (registered trademark) E, Exol (registered trademark) Hexane, Heptane, E, D30, D40, D60, D80, D95, D110, One or more types selected from petroleum solvents such as D130 (manufactured by ExxonMobil) can be used.

As the liquid resin, one or more types selected from, for example, liquid acrylic resin, liquid epoxy resin, liquid polyester resin, liquid urethane resin, etc. can be used.

As the liquid plasticizer, for example, a liquid plasticizer for plastics can be used.

The components contained in the near-infrared absorbing particle dispersion are not limited to the above-mentioned near-infrared absorbing particles and liquid medium. The near-infrared absorbing particle dispersion liquid can further contain optional components as required.

For example, an acid or an alkali may be added to the near-infrared absorbing particle dispersion as necessary to adjust the pH of the dispersion.

In addition, in the above-mentioned near-infrared absorbing particle dispersion, various surfactants and coupling agents are used to further improve the dispersion stability of the near-infrared absorbing particles and to avoid coarsening of the dispersed particle size due to reaggregation. etc. can also be added to the near-infrared absorbing particle dispersion as a dispersant.

Dispersants such as surfactants and coupling agents can be selected depending on the application, but the dispersant may contain one or more types selected from amine-containing groups, hydroxyl groups, carboxyl groups, and epoxy groups. It is preferable to have it as a functional group. These functional groups adsorb to the surface of the near-infrared absorbing particles to prevent aggregation, and have the effect of uniformly dispersing the near-infrared absorbing particles even in an infrared shielding film formed using the near-infrared absorbing particles, for example. The dispersant is more preferably a polymeric dispersant having one or more types selected from the above functional groups (functional group group) in its molecule.

Commercially available dispersants that can be suitably used include Solspers (registered trademark) 9000, 12000, 17000, 20000, 21000, 24000, 26000, 27000, 28000, 32000, 35100, 54000, 250 (manufactured by Japan Lubrizol Co., Ltd.). ), EFKA (registered trademark) 4008, 4009, 4010, 4015, 4046
, 4047, 4060, 4080, 7462, 4020, 4050, 4055, 4400, 4401, 4402, 4403, 4300, 4320, 4330, 4340, 6220, 6225, 6700, 6780, 6782, 8503 (manufactured by Efka Additives) , Ajisper (registered trademark) PA111, PB821, PB822, PN411, Famex L-12 (manufactured by Ajinomoto Fine Techno Co., Ltd.), DisperBYK (registered trademark) 101, 102, 106, 108, 111, 116, 130, 140, 142 , 145, 161, 162, 163, 164, 166, 167, 168, 170, 171, 174, 180, 182, 192, 193, 2000, 2001, 2020, 2025, 2050, 2070, 2155, 2164, 220S, 300 , 306, 320, 322, 325, 330, 340, 350, 377, 378, 380N, 410, 425, 430 (manufactured by Pick Chemiichi Japan Co., Ltd.), Disparon (registered trademark) 1751N, 1831, 1850, 1860, 1934 , DA-400N, DA-703-50, DA-725, DA-705, DA-7301, DN-900, NS-5210, NVI-8514L (manufactured by Kusumoto Kasei Co., Ltd.), Alphon (registered trademark) UC-3000 , UF-5022, UG-4010, UG-4035, UG-4070 (manufactured by Toagosei Co., Ltd.) and the like.

The method for dispersing near-infrared absorbing particles into a liquid medium is not particularly limited as long as it is a method that can disperse near-infrared absorbing particles into a liquid medium. At this time, it is preferable that the particles can be dispersed so that the average particle size of the near-infrared absorbing particles is 200 nm or less, and more preferably that the average particle size of the near-infrared absorbing particles is 0.1 nm or more and 200 nm or less.

Examples of a dispersion treatment method for near-infrared absorbing particles in a liquid medium include a dispersion treatment method using a device such as a bead mill, a ball mill, a sand mill, a paint shaker, and an ultrasonic homogenizer. Among them, grinding and dispersing with a media agitation mill such as a bead mill, ball mill, sand mill, paint shaker, etc. using media (beads, poles, ottawa sand) shortens the time required to obtain the desired average particle size. Preferable from this point of view. Through the grinding and dispersion process using a media stirring mill, near-infrared absorbing particles are dispersed into the liquid medium, and at the same time, near-infrared absorbing particles collide with each other and the medium collides with near-infrared absorbing particles, resulting in atomization. However, near-infrared absorbing particles can be made into finer particles and dispersed. That is, it is subjected to pulverization and dispersion treatment.

The average particle diameter of the near-infrared absorbing particles is preferably 0.1 nm or more and 200 nm or less, as described above. This is because if the average particle size is small, scattering of light in the visible light range of wavelengths from 400 nm to 780 nm due to geometric scattering or Mie scattering is reduced. As a result of such light scattering being reduced, for example, a near-infrared absorbing particle dispersion in which near-infrared absorbing particles are dispersed in a resin or the like, which is obtained using the near-infrared absorbing particle dispersion of this embodiment, becomes like frosted glass. , it is possible to avoid not being able to obtain clear transparency. That is, when the average particle size becomes 200 nm or less, the geometric scattering or Mie scattering mode becomes weaker and becomes the Rayleigh scattering mode. This is because in the Rayleigh scattering region, scattered light is proportional to the sixth power of the dispersed particle size, so as the dispersed particle size decreases, scattering decreases and transparency improves. When the average particle size is 100 nm or less, the amount of scattered light becomes extremely small, which is preferable.

By the way, the dispersion state of the near-infrared absorbing particles in the near-infrared absorbing particle dispersion obtained using the near-infrared absorbing particle dispersion liquid of this embodiment, in which the near-infrared absorbing particles are dispersed in a solid medium such as a resin, is As long as a known method for adding the dispersion to the dispersion is carried out, there will be no agglomeration that is larger than the average particle size of the near-infrared absorbing particles in the dispersion.

In addition, if the average particle size of the near-infrared absorbing particles is 0.1 nm or more and 200 nm or less, the manufactured near-infrared absorbing particle dispersion or its molded product (plate, sheet, etc.) will be a gray color with a monotonically decreased transmittance. You can avoid becoming a system.

The content of near-infrared absorbing particles in the near-infrared absorbing particle dispersion of the present embodiment is not particularly limited, but is preferably, for example, 0.01% by mass or more and 80% by mass or less. This is because a sufficient solar radiation absorption rate can be exhibited by setting the content of near-infrared absorbing particles to 0.01% by mass or more. Further, by setting the content to 80% by mass or less, the near-infrared absorbing particles can be uniformly dispersed in the dispersion medium.
[4] Near-infrared curable ink composition The near-infrared curable ink composition according to this embodiment will be described.

The near-infrared curable ink composition of this embodiment can include a thermosetting resin or a thermoplastic resin and near-infrared absorbing particles. That is, as shown in FIG. 6, for example, the near-infrared curable ink composition 60 of this embodiment includes the above-mentioned near-infrared absorbing particles 61 and a resin component 62 that is a thermosetting resin or a thermoplastic resin. can be included. The near-infrared absorbing particles 61 are preferably dispersed in the resin component 62.

FIG. 6 is a schematic diagram, and the near-infrared curable ink composition of this embodiment is not limited to this form. For example, although the near-infrared absorbing particles 61 are shown as spherical particles in FIG. 6, the shape of the near-infrared absorbing particles 61 is not limited to this shape, and can have any shape. In addition to the near-infrared absorbing particles 61 and the resin component 62, the near-infrared curable ink composition 60 can also contain other additives as needed.

Note that the near-infrared absorbing particles described above can be used as the near-infrared absorbing particles. Therefore, the near-infrared absorbing particles can contain cesium tungstate. Cesium tungstate has a predetermined crystal structure, for example, is represented by the general formula Cs _x W _y O _z , and in a ternary composition diagram with Cs, W, and O as the vertices, , z=2.5y, y=5x, and Cs ₂ O:WO ₃ =m:n (m and n are integers). Note that the thermosetting resin can be in an uncured state, specifically, in a fluid state.

The components contained in the near-infrared curable ink composition of this embodiment will be described below.
(1) Resin component The near-infrared curable ink composition of this embodiment can contain a resin component, specifically a thermosetting resin or a thermoplastic resin.
(1-1) Regarding thermosetting resins Thermosetting resins are not particularly limited, but include, for example, epoxy resins, urethane resins, acrylic resins, urea resins, melamine resins, phenol resins, ester resins, polyimide resins, and silicone resins. One or more selected from polyester resins, unsaturated polyester resins, etc. can be used.

These thermosetting resins are uncured resins that are cured by being given thermal energy from near-infrared absorbing particles that have been irradiated with near-infrared rays. The thermosetting resin may contain a monomer or oligomer that forms the thermosetting resin through a curing reaction, and a known curing agent that is added as appropriate. Furthermore, a known curing accelerator may be added to the curing agent.
(1-2) Regarding thermoplastic resins Examples of thermoplastic resins include polyester resins, polycarbonate resins, acrylic resins, polystyrene resins, polyamide resins, vinyl chloride resins, olefin resins, fluororesins, polyvinyl acetate resins, and thermoplastic polyurethane resins. , acrylonitrile butadiene styrene resin, polyvinyl acetal resin, acrylonitrile-styrene copolymer resin, ethylene-vinyl acetate copolymer resin, etc. can be used.

These thermoplastic resins are once melted by being given thermal energy from near-infrared absorbing particles that have been irradiated with near-infrared rays, and can be hardened into a desired shape by subsequent cooling.
(2) Near-infrared absorbing particles As the near-infrared absorbing particles, the near-infrared absorbing particles described above can be used. Since near-infrared absorbing particles have already been explained, their explanation will be omitted here.

The content of near-infrared absorbing particles in the near-infrared curable ink composition of the present embodiment is not particularly limited, and can be selected depending on the characteristics required of the near-infrared curable ink composition.

The amount of near-infrared absorbing particles contained in the near-infrared curable ink composition of this embodiment is selected and added so that the uncured thermosetting resin can be cured during the curing reaction. Good. Further, the amount of near-infrared absorbing particles contained in the near-infrared curable ink composition of the present embodiment may be selected and added such that the thermoplastic resin is dissolved during the heat dissolution reaction.

Therefore, the amount of near-infrared absorbing particles per coating area of the near-infrared curable ink composition can be selected and determined by considering the coating thickness when applying the near-infrared curable ink composition.

The method for dispersing the near-infrared absorbing particles in the near-infrared curable ink composition is not particularly limited, but it is preferable to use a wet media mill or the like.
(3) Other components The near-infrared curable ink composition of this embodiment can be composed only of the above-mentioned resin component and near-infrared absorbing particles, but it can also contain further arbitrary components, such as for the purpose Depending on the situation, pigments, dyes, dispersants, solvents, etc. described below may also be contained. Note that even if the near-infrared curable ink composition is composed only of a resin component and near-infrared absorbing particles as described above, it is not excluded that it contains unavoidable components that are mixed in during the manufacturing process.
(3-1) Pigments and dyes As described above, the near-infrared curable ink composition of this embodiment uses one or more types of pigments selected from organic pigments, inorganic pigments, and dyes to color the ink composition. may further include.
(3-1-1) Pigment The pigment is not particularly limited, and any known pigment can be used without particular restriction, and one selected from organic pigments such as insoluble pigments and lake pigments, and inorganic pigments such as carbon black, etc. More than one type can be preferably used.

These pigments are preferably present in a dispersed state in the near-infrared curable ink composition of this embodiment. As a method for dispersing these pigments, any known method can be used without particular limitation.

The above insoluble pigments are not particularly limited, but include, for example, azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine, and thiazine. , dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole, etc. can be used.

Although the organic pigment is not particularly limited, specific pigment names that can be preferably used are listed below.

Examples of magenta or red pigments include C.I. I. Pigment Red 2, C. I. Pigment Red 3, C. I. Pigment Red 5, C. I. Pigment Red 6, C. I. Pigment Red 7, C. I. Pigment Red 15, C. I. Pigment Red 16, C. I. Pigment Red 48:1, C.I. I. Pigment Red 53:1, C.I. I. Pigment Red 57:1, C.I. I. Pigment Red 122, C. I. Pigment Red 123, C. I. Pigment Red 139, C. I. Pigment Red 144, C. I. Pigment Red 149, C. I. Pigment Red 166, C. I. Pigment Red 177, C. I. Pigment Red 178, C. I. Pigment Red 202, C. I. Pigment Red 222, C. I. Pigment Violet 19 and the like.

Examples of pigments for orange or yellow include C.I. I. Pigment Orange 31, C. I. Pigment Orange 43, C. I. Pigment Yellow 12, C. I. Pigment Yellow 13, C. I. Pigment Yellow 14, C. I. Pigment Yellow 15, C. I. Pigment Yellow 15:3, C.I. I. Pigment Yellow 17, C. I. Pigment Yellow 74, C. I. Pigment Yellow 93, C. I. Pigment Yellow 128, C. I. Pigment Yellow 94, C. I. Pigment Yellow 138 and the like.

Examples of green or cyan pigments include C.I. I. Pigment Blue 15, C. I. Pigment Blue 15:2, C. I. Pigment Blue 15:3, C. I. Pigment Blue 16, C. I. Pigment Blue 60, C. I. Pigment Green 7 and the like.

Examples of black pigments include C.I. I. Pigment Black 1, C. I. Pigment Black 6, C. I. Pigment Black 7 and the like.

Inorganic pigments are not particularly limited, but examples include carbon black, titanium dioxide, zinc sulfide, zinc oxide, zinc phosphate, mixed metal oxide phosphates, iron oxide, iron manganese oxide, chromium oxide, ultramarine, and nickel. or chromium antimony titanium oxide, cobalt oxide, aluminum, aluminum oxide, silicon oxide, silicate, zirconium oxide, mixed oxides of cobalt and aluminum, molybdenum sulfide, rutile mixed phase pigments, rare earth sulfides, bismuth vanadate, Extender pigments made of aluminum hydroxide or barium sulfate, etc. can be preferably used.

The average dispersed particle diameter of the dispersed pigment contained in the near-infrared curable ink composition according to the present embodiment is not particularly limited, but is preferably, for example, 1 nm or more and 100 nm or less. This is because when the average dispersed particle size of the pigment dispersion is 1 nm or more and 100 nm or less, the storage stability in the near-infrared curable ink composition is particularly good. The average dispersed particle size can be measured, for example, using ELS-8000 manufactured by Otsuka Electronics Co., Ltd., which is a particle size measuring device based on a dynamic light scattering method.
(3-1-2) Dye The dye is not particularly limited either, and either oil-soluble dyes or water-soluble dyes can be used, and yellow dyes, magenta dyes, cyan dyes, etc. can be preferably used.

Examples of yellow dyes include aryl or heteryl azo dyes containing phenols, naphthols, anilines, pyrazolones, pyridones, and open-chain active methylene compounds as coupling components; azomethine dyes such as benzylidene dyes and monomethine oxonol dyes; quinone dyes such as naphthoquinone dyes and anthraquinone dyes; other dye types include quinophthalone dyes, nitro-nitroso dyes, etc. Dyes, acridine dyes, acridinone dyes, etc. can be mentioned. These dyes may exhibit yellow color only when a part of the chromophore dissociates, and in this case, the counter cation may be an alkali metal or an inorganic cation such as ammonium, or may be an inorganic cation such as pyridinium or pyridinium. It may be an organic cation such as a quaternary ammonium salt, or a polymer cation having such a partial structure.

Magenta dyes include, for example, aryl or heterolazo dyes having phenols, naphthols, or anilines as coupling components; for example, azomethine dyes having pyrazolones or pyrazolotriazoles as coupling components; for example, arylidene dyes, styryl dyes, merocyanine dyes; dyes, methine dyes such as oxonol dyes; carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes, xanthene dyes; quinone dyes such as naphthoquinone, anthraquinone, anthrapyridone, etc.; condensation polyester dyes such as dioxazine dyes, etc. Examples include cyclic dyes. These dyes may exhibit magenta only when a part of the chromophore dissociates, and the counter cation in this case may be an alkali metal or an inorganic cation such as ammonium, or may be a pyridinium, pyridinium, or It may be an organic cation such as a quaternary ammonium salt, or a polymer cation having such a partial structure.

Examples of cyan dyes include azomethine dyes such as indoaniline dyes and indophenol dyes; polymethine dyes such as cyanine dyes, oxonol dyes, and merocyanine dyes; carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes, and xanthene dyes; phthalocyanine Dyes; anthraquinone dyes; for example, aryl or heterolazo dyes having phenols, naphthols, or anilines as coupling components, and indigo/thioindigo dyes. These dyes may exhibit cyan color only when a part of the chromophore dissociates, and in this case, the counter cation may be an alkali metal or an inorganic cation such as ammonium, or may be an inorganic cation such as pyridinium or pyridinium. It may be an organic cation such as a quaternary ammonium salt, or a polymer cation having such a partial structure. Additionally, black dyes such as polyazo dyes can also be used.

Water-soluble dyes are not particularly limited either, and direct dyes, acid dyes, food dyes, basic dyes, reactive dyes, and the like can be preferably used.

Specific dye names that can be preferably used as water-soluble dyes are listed below.

C. I. Direct Red 2, 4, 9, 23, 26, 31, 39, 62, 63, 72, 75, 76, 79, 80, 81, 83, 84, 89, 92, 95, 111, 173, 184, 207, 211, 212, 214, 218, 21, 223, 224, 225, 226, 227, 232, 233, 240, 241, 242, 243, 247,
C.I. Direct Violet 7, 9, 47, 48, 51, 66, 90, 93, 94, 95, 98, 100, 101,
C.I. Direct Yellow 8, 9, 11, 12, 27, 28, 29, 33, 35, 39, 41, 44, 50, 53, 58, 59, 68, 86, 87, 93, 95, 96, 98, 100, 106, 108, 109, 110, 130, 132, 142, 144, 161, 163,
C. I. Direct Blue 1, 10, 15, 22, 25, 55, 67, 68, 71, 76, 77, 78, 80, 84, 86, 87, 90, 98, 106, 108, 109, 151, 156, 158, 159, 160, 168, 189, 192, 193, 194, 199, 200, 201, 202, 203, 207, 211, 213, 214, 218, 225, 229, 236, 237, 244, 248, 249, 251, 252, 264, 270, 280, 288, 289, 291,
C.I. Direct Black 9, 17, 19, 22, 32, 51, 56, 62, 69, 77, 80, 91, 94, 97, 108, 112, 113, 114, 117, 118, 121, 122, 125, 132, 146, 154, 166, 168, 173, 199,
C.I. Acid Red 35, 42, 52, 57, 62, 80, 82, 111, 114, 118, 119, 127, 128, 131, 143, 151, 154, 158, 249, 254, 257, 261, 263, 266, 289, 299, 301, 305, 336, 337, 361, 396, 397,
C.I. Acid Violet 5, 34, 43, 47, 48, 90, 103, 126,
C.I. Acid Yellow 17, 19, 23, 25, 39, 40, 42, 44, 49, 50, 61, 64, 76, 79, 110, 127, 135, 143, 151, 159, 169, 174, 190, 195, 196, 197, 199, 218, 219, 222, 227,
C. I. Acid Blue 9, 25, 40, 41, 62, 72, 76, 78, 80, 82, 92, 106, 112, 113, 120, 127:1, 129, 138, 143, 175, 181, 205, 207, 220, 221, 230, 232, 247, 258, 260, 264, 271, 277, 278, 279, 280, 288, 290, 326,
C. I. acid black 7, 24, 29, 48, 52:1, 172,
C. I. Reactive Red 3, 13, 17, 19, 21, 22, 23, 24, 29, 35, 37, 40, 41, 43, 45, 49, 55,
C. I. Reactive Violet 1, 3, 4, 5, 6, 7, 8, 9, 16, 17, 22, 23, 24, 26, 27, 33, 34,
C. I. Reactive Yellow 2, 3, 13, 14, 15, 17, 18, 23, 24, 25, 26, 27, 29, 35, 37, 41, 42,
C. I. Reactive Blue 2, 3, 5, 8, 10, 13, 14, 15, 17, 18, 19, 21, 25, 26, 27, 28, 29, 38,
C. I. Reactive Black 4, 5, 8, 14, 21, 23, 26, 31, 32, 34,
C. I. Basic Red 12, 13, 14, 15, 18, 22, 23, 24, 25, 27, 29, 35, 36, 38, 39, 45, 46,
C. I. Basic violet 1, 2, 3, 7, 10, 15, 16, 20, 21, 25, 27, 28, 35, 37, 39, 40, 48,
C. I. Basic yellow 1, 2, 4, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 39, 40,
C. I. Basic blue 1, 3, 5, 7, 9, 22, 26, 41, 45, 46, 47, 54, 57, 60, 62, 65, 66, 69, 71,
C. I. Basic Black 8, etc. are mentioned.

It is preferable that the particle size of the pigment, which is a coloring material, as described above, is determined in consideration of the characteristics of a coating device for a near-infrared curable ink composition.

(3-2) Dispersant The near-infrared curable ink composition of this embodiment may further contain a dispersant. That is, the near-infrared absorbing particles described above may be dispersed together with a dispersant into a thermosetting resin, a thermoplastic resin, or a solvent which is an optional component described below. By adding a dispersant, the near-infrared absorbing particles can be easily dispersed in the near-infrared curable ink composition. Furthermore, when a coating film of the near-infrared curable ink composition is cured, variations in curing can be particularly suppressed.

The dispersant used in the near-infrared curable ink composition of this embodiment is not particularly limited, and any commercially available dispersant can be used, for example. However, the molecular structure of the dispersant has a main chain of polyester, polyacrylic, polyurethane, polyamine, polycaptolactone, or polystyrene, and the functional groups include amino, epoxy, carboxyl, and hydroxyl groups. , a sulfo group, etc. are preferred. A dispersant having such a molecular structure is difficult to change in quality when the coating film of the near-infrared curable ink composition of this embodiment is intermittently irradiated with near-infrared rays for several tens of seconds. Therefore, it is possible to particularly suppress the occurrence of defects such as discoloration caused by the deterioration.

Specific examples of commercially available dispersants that can be suitably used include SOLSPERSE 3000, SOLSPERSE 9000, SOLSPERSE 11200, SOLSPERSE 13000, SOLSPERSE 13240, SOLSPERSE 13650, and SOLSPERS manufactured by Nippon Lubrizol Co., Ltd. E13940, SOLSPERSE16000, SOLSPERSE17000, SOLSPERSE18000, SOLSPERSE20000, SOLSPERSE21000, SOLSPERSE24000SC, SOLSPERSE24000GR, SOLSPERSE26000, SOLSPERSE27000, SOLSPERSE28000, SOLSPERSE31845, SOLSPERSE32000, SOLSPERSE32500, SOLSPERSE32550 , SOLSPERSE32600, SOLSPERSE33000, SOLSPERSE33500, SOLSPERSE34750, SOLSPERSE35100, SOLSPERSE35200, SOLSPERSE36600, SOLSPERSE37500, SO LSPERSE38500, SOLSPERSE39000, SOLSPERSE41000, SOLSPERSE41090, SOLSPERSE53095, SOLSPERSE55000, SOLSPERSE56000, SOLSPERSE76500, etc.;
Disperbyk-101, Disperbyk-103, Disperbyk-107, Disperbyk-108, Disperbyk-109, Disperbyk-110, Disperbyk-111, Disperbyk-112 manufactured by Big Chemie Japan Co., Ltd. , Disperbyk-116, Disperbyk-130, Disperbyk-140 , Disperbyk-142, Disperbyk-145, Disperbyk-154, Disperbyk-161, Disperbyk-162, Disperbyk-163, Disperbyk-164, Disperbyk-165, Disperby k-166, Disperbyk-167, Disperbyk-168, Disperbyk-170, Disperbyk -171, Disperbyk-174, Disperbyk-180, Disperbyk-181, Disperbyk-182, Disperbyk-183, Disperbyk-184, Disperbyk-185, Disperbyk-190, Disp erbyk-2000, Disperbyk-2001, Disperbyk-2020, Disperbyk-2025 , Disperbyk-2050, Disperbyk-2070, Disperbyk-2095, Disperbyk-2150, Disperbyk-2155, Anti-Terra-U, Anti-Terra-203, Anti-Terra-204, BY K-P104, BYK-P104S, BYK-220S , BYK-6919, etc.;
Manufactured by BASF Japan Co., Ltd. EFKA4008, EFKA4046, EFKA4047, EFKA4015, EFKA4020, EFKA4050, EFKA4055, EFKA4060, EFKA4080, EFKA4300, EFKA4330, EFKA4400, E FKA4401, EFKA4402, EFKA4403, EFKA4500, EFKA4510, EFKA4530, EFKA4550, EFKA4560, EFKA4585, EFKA4800 , EFKA5220, EFKA6230, JONCRYL67, JONCRYL678, JONCRYL586, JONCRYL611, JONCRYL680, JONCRYL682, JONCRYL690, JONCRYL819, JONCRYL-JDX5050 etc;
Examples include Ajisper PB-711, Ajisper PB-821, and Ajisper PB-822 manufactured by Ajinomoto Fine Techno Co., Inc.

In addition, as a dispersant, the dispersant explained in the near-infrared particle dispersion mentioned above can also be used.

(3-3) Solvent In the near-infrared curable ink composition of this embodiment, a solvent can be used together with the thermosetting resin or thermoplastic resin. That is, the near-infrared curable ink composition of this embodiment may further contain a solvent.

In this case, as a solvent for the near-infrared curable ink composition, for example, an epoxy group that reacts with the monomer or oligomer of the thermosetting resin contained in the uncured thermosetting resin during the curing reaction of the thermosetting resin. It is also preferable to use a reactive organic solvent having a functional group such as.

By adding a solvent, the viscosity of the near-infrared curable ink composition can be adjusted. This is because by adjusting the viscosity of the near-infrared curable ink composition, the coatability of the near-infrared curable ink composition and the smoothness of the coating film can be easily ensured.

The solvent is not particularly limited, but examples include water, alcohols such as methanol, ethanol, propanol, butanol, isopropyl alcohol, isobutyl alcohol, and diacetone alcohol, ethers such as methyl ether, ethyl ether, and propyl ether, esters, Various organic solvents such as ketones such as acetone, methyl ethyl ketone, diethyl ketone, cyclohexanone, and imbutyl ketone, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, polyethylene glycol, and polypropylene glycol can be used.

Note that as the solvent, the liquid medium described above in connection with the near-infrared absorbing particle dispersion can also be used.
[5] Method for producing near-infrared curable ink composition As described above, the near-infrared curable ink composition of this embodiment is produced by adding near-infrared absorbing particles to uncured thermosetting resin or thermoplastic resin. It can be prepared by Further, the near-infrared curable ink composition of this embodiment may be prepared by dispersing near-infrared absorbing particles in an appropriate solvent and then adding an uncured thermosetting resin or thermoplastic resin. . The near-infrared curable ink composition of the present embodiment can also be prepared by adding an uncured thermosetting resin or thermoplastic resin to the near-infrared absorbing particle dispersion described above.

The near-infrared curable ink composition of this embodiment contains the above-mentioned near-infrared absorbing particles, so when it is applied onto a substrate and irradiated with near-infrared rays to form a cured film, it becomes more neutral. It is possible to change the color tone. In addition, since the above-mentioned near-infrared absorbing particles have excellent near-infrared absorption properties, when irradiated with near-infrared rays, etc., they can supply sufficient heat and sufficiently increase the adhesion of the resulting cured film to the substrate. can.

In addition, according to the near-infrared curable ink composition of this embodiment, a three-dimensional object can also be modeled on a substrate. In other words, it is also a near-infrared curable ink composition that is ideal for stereolithography for modeling three-dimensional objects.

As described above, by containing the solvent in the near-infrared curable ink composition of this embodiment, its viscosity can be adjusted, so that the ease of handling when applying it to a substrate or the like can be improved.

However, as described above, the near-infrared curable ink composition of this embodiment does not need to contain a solvent. Since the near-infrared curable ink composition of the present embodiment does not contain a solvent, operations such as evaporating the solvent can be omitted, thereby increasing the efficiency when curing the applied product of the near-infrared curable ink composition. be able to.

In addition, when the near-infrared curable ink composition of this embodiment contains a solvent, the method for removing the solvent after applying the near-infrared curable ink composition is not particularly limited, and for example, a heating distillation method with a reduced pressure operation is used. etc. can be used.
[6] Near-infrared cured film, method for producing near-infrared cured film The near-infrared cured film of this embodiment can be a cured product of the above-mentioned near-infrared curable ink composition.

The near-infrared cured film of this embodiment can be produced, for example, by the method for producing a near-infrared cured product described below.

Specifically, after applying the above-mentioned near-infrared curable ink composition to the surface of a substrate etc. (coating step), the solvent etc. are removed as necessary, and near-infrared rays are irradiated to cure the near-infrared curable ink composition. The infrared curable ink composition can be cured (curing step).

The above-mentioned coating step and curing step can be repeated, and a near-infrared cured film having a desired shape and size can be obtained. Furthermore, a three-dimensional object can be formed on the substrate, and in this case, it can also be called a near-infrared cured product.
[7] Method for producing near-infrared cured product The method for producing near-infrared cured product according to the present embodiment can include the following coating process and curing process.

In the coating step, the above-mentioned near-infrared curable ink composition can be applied onto the substrate to form a coating film.

In the curing step, the near-infrared curable ink composition can be cured by irradiating the coating film with near-infrared rays.

Since the near-infrared curable ink composition described above has excellent near-infrared absorption characteristics, the near-infrared curable ink composition is applied to obtain a coating film, and the coating film is irradiated with near-infrared rays to cure it. As a result, a near-infrared cured film that exhibits excellent adhesion to a predetermined substrate can be obtained.

A colored film can also be obtained by adding at least one type of various pigments or dyes to the near-infrared curable ink composition. Since the colored film has almost no effect on the color tone due to near-infrared absorbing particles, the colored film can also be used for color filters of liquid crystal displays and the like.

In the near-infrared cured film of this embodiment, the reason for the excellent adhesion is that the near-infrared absorbing particles absorb the irradiated near-infrared rays and generate heat, and the heat energy of the heat is transferred to the uncured heat. It is thought that this is because the reaction of the monomers, oligomers, etc. contained in the curable resin promotes reactions such as polymerization reactions, condensation reactions, and addition reactions, thereby causing the curing reaction of the thermosetting resin. In addition, in the near-infrared cured film of this embodiment, the reason for the above-mentioned excellent adhesion is that sufficient heat is supplied by the heat generation of the near-infrared absorbing particles by near-infrared irradiation, and the thermoplastic resin is melted and cooled. This is also thought to be due to hardening caused by.

The near-infrared curable ink composition described above may contain a solvent, but the solvent and the like can also be volatilized by the heat generated by the near-infrared absorbing particles.

When the near-infrared absorption curable ink composition described above contains a thermosetting resin as a resin component, the near-infrared cured film formed using the near-infrared absorption curable ink composition is further irradiated with near-infrared rays. Even if the cured film is not melted again, the cured film will not melt again. This is because such a near-infrared cured film contains a cured product of a thermosetting resin, so even if the near-infrared absorbing particles generate heat due to near-infrared irradiation, they do not melt again.

This characteristic is achieved by repeating application of the near-infrared curable ink composition of this embodiment and near-infrared irradiation, and repeatedly laminating the cured product of the near-infrared curable ink composition, thereby creating a three-dimensional object. When applied to a method, it is particularly effective in combination with the above-mentioned excellent adhesion to the substrate.

Each step will be explained below.
(1) Coating process In the coating process, the above-mentioned near-infrared curable ink composition can be applied onto the substrate to form a coating film.

In the coating step, the material of the substrate (base material) to which the near-infrared curable ink composition is applied is not particularly limited.

As the substrate, for example, one or more types of substrates selected from paper, resin, glass, etc. can be used.

The above-mentioned resin is not particularly limited, but includes, for example, polyester such as PET (polyethylene terephthalate), acrylic, urethane, polycarbonate, polyethylene, ethylene-vinyl acetate copolymer, vinyl chloride, fluororesin, polyimide, polyacetal, polypropylene, and nylon. One or more types selected from the following can be used.

The shape of the substrate is not particularly limited, and can be shaped in accordance with the shape required for the near-infrared cured product, for example, can be shaped like a plate.

The method of applying the near-infrared curable ink composition to the surface of the substrate is not particularly limited, but includes dipping, flow coating, spraying, bar coating, spin coating, gravure coating, roll coating, screen printing, A blade coating method or the like can be used.
(2) Curing process In the curing process, the near-infrared curable ink composition can be cured by irradiating the coating film with near-infrared rays.

As a method for curing the near-infrared curable ink composition, infrared irradiation is preferred, and near-infrared irradiation is more preferred. Near-infrared rays have a high energy density and can efficiently provide the energy necessary for curing the resin in the near-infrared curable ink composition.

It is also preferable to cure the near-infrared curable ink composition by combining infrared irradiation with any method selected from known methods. For example, methods such as heating, blowing air, and irradiation with electromagnetic waves may be used in combination with infrared irradiation.

In addition, in this specification, infrared rays refer to electromagnetic waves having wavelengths in the range of 0.1 μm or more and 1 mm or less, near infrared rays refer to infrared waves with wavelengths of 0.75 μm or more and 4 μm or less, and far infrared rays refer to infrared waves with wavelengths of 4 μm or more and 1000 μm or less. refers to infrared rays. Regardless of which infrared rays, generally called far infrared rays or near infrared rays, are irradiated, the near infrared curable ink composition can be cured and the same effect can be obtained. However, when near infrared rays are irradiated, the coating film can be cured more efficiently in a shorter time.

As described above, when curing the near-infrared curable ink composition, electromagnetic waves can also be irradiated with near-infrared rays. Microwaves can be suitably used as such electromagnetic waves. Note that microwave refers to electromagnetic waves having a wavelength in a range of 1 mm or more and 1 m or less.

It is preferable that the irradiated microwave has a power of 200 W or more and 1000 W or less. If the power is 200 W or more, the vaporization of the organic solvent remaining in the near-infrared curable ink composition is promoted, and if the power is 1000 W or less, the irradiation conditions are mild, and the near-infrared curing of the base material, thermosetting resin, etc. There is no fear that the resin component contained in the mold ink composition will change in quality.

The time period for irradiating the near-infrared curable ink composition with infrared rays varies depending on the energy and wavelength of the irradiation, the composition of the near-infrared curable ink, and the amount of near-infrared curable ink applied, and is not particularly limited. For example, the above-mentioned infrared ray irradiation time is generally preferably 0.1 seconds or more. By setting the irradiation time to 0.1 seconds or more, sufficient infrared rays can be irradiated to cure the near-infrared curable ink composition. For example, by increasing the irradiation time, it is possible to sufficiently dry the solvent in the near-infrared absorption curable ink composition, but with high-speed printing and coating in mind, the irradiation time is 30 seconds. It is preferably within 10 seconds, and more preferably within 10 seconds.

The source of infrared rays is not particularly limited, and infrared rays may be obtained directly from a heat source, or effective infrared rays may be obtained from there through a heating medium. For example, infrared rays can be obtained by heating a discharge lamp of mercury, xenon, cesium, sodium, etc., a carbon dioxide gas laser, or an electric resistor such as platinum, tungsten, nichrome, kanthal, etc. Note that a halogen lamp is a preferred radiation source. Halogen lamps have advantages such as good thermal efficiency and quick start-up.

The coating film may be irradiated with infrared rays from the near-infrared curable ink-coated side of the substrate or from the back side. It is also preferable to perform irradiation from both sides at the same time, and it is also preferable to combine the irradiation with elevated temperature drying or blow drying. Moreover, it is more preferable to use a light condensing plate if necessary. By combining these methods, it becomes possible to cure the near-infrared curable ink composition with short-time infrared irradiation.

In addition, according to the method for producing a near-infrared cured product of this embodiment, the above-mentioned near-infrared cured film can be produced. Moreover, a three-dimensional object can also be modeled by repeatedly laminating cured products of near-infrared curable ink compositions. That is, a near-infrared cured product having a desired three-dimensional structure can also be produced by repeatedly performing the coating process and the irradiation process described above.

The near-infrared cured film and near-infrared cured product of this embodiment can contain a cured thermosetting resin or thermoplastic resin and the above-mentioned near-infrared absorbing particles. The near-infrared absorbing particles are preferably contained in a thermosetting resin or a thermoplastic resin and are in a dispersed state. The near-infrared cured film and near-infrared cured product of this embodiment may further contain the pigments, dyes, dispersants, etc. described above. The components contained in the near-infrared cured film and the near-infrared cured product of this embodiment may be partially or entirely denatured by irradiation with near-infrared rays, heat generation, etc. in the curing process.

According to the method for producing a near-infrared cured product of this embodiment, stereolithography can be performed. That is, it is also possible to use a stereolithography method that includes the coating process and the curing process described above.

The present invention will be specifically described below with reference to Examples. However, the present invention is not limited to the following examples.
(Evaluation method)
First, evaluation methods in the following Examples and Comparative Examples will be explained.
(chemical analysis)
Chemical analysis of the obtained near-infrared absorbing particles was performed by atomic absorption spectrometry (AAS) for Cs and by ICP-OES for W (tungsten). For O, a LECO light element analyzer (ON-836) was used.
(X-ray diffraction measurement)
The X-ray diffraction measurement was carried out by powder XRD measurement using a Cu-Kα ray with an X'Pert-PRO/MPD apparatus manufactured by Spectris.

(Optical properties of near-infrared cured film)
The L ^* a ^* b ^* color index of the near-infrared cured film is determined by calculating the tristimulus values X, Y, and Z for a D65 standard light source and a light source angle of 10° in accordance with JIS Z 8701 (1999). It was determined according to JIS Z 8729 (2004).
[Example 1]
(Production and evaluation of near-infrared absorbing particles)
Cesium carbonate (Cs ₂ CO ₃ ) and tungsten trioxide (WO ₃ ) were weighed, mixed, and kneaded in a total amount of 20 g so that the molar ratio was Cs ₂ CO ₃ :WO ₃ =1:6, The obtained kneaded product was placed in a carbon boat and dried in the atmosphere at 110° C. for 12 hours. As a result, a cesium tungsten oxide precursor powder, which is a raw material for a compound containing Cs and W, was obtained.

The above cesium tungsten oxide precursor powder was placed on an alumina boat, placed in a heating muffle furnace, and heated to 550°C for 1 hour while flowing a mixed gas of superheated steam and nitrogen gas at a volume ratio of 50:50. held. Note that the above mixed gas is expressed in Table 1 as 50% N ₂ -50% superheated H ₂ O. Next, the gas to be supplied was changed to 100% by volume nitrogen gas, and while flowing nitrogen gas, the temperature was raised after being held at 550°C for 0.5 hours, and then held at 800°C for 1 hour. Thereafter, the temperature was lowered to room temperature to obtain a slightly greenish white powder (first heat treatment step).

The X-ray powder diffraction pattern of this white powder was identified as Cs ₄ W ₁₁ O ₃₅ (ICDD 00-51-1891).

Next, this white powder was placed in a carbon boat and placed in a tube furnace, and the temperature was raised in a 1 volume % H ₂ -Ar gas flow (expressed as 1% H ₂ -Ar in Table 1). The mixture was maintained at ℃ for 1 hour for reduction. Next, the gas to be supplied was changed to 100% by volume Ar gas, and the temperature was maintained at 550° C. for 30 minutes while flowing Ar gas. Subsequently, the temperature was raised to 800° C. and heated for 1 hour, and then the temperature was lowered to room temperature to obtain pale light blue powder A (second heat treatment step).

As shown in Figure 2, the XRD powder pattern of the powder A obtained here is a broad one in which the main phase is hexagonal Cs _0.32 WO ₃ and the second phase is orthorhombic Cs ₄ W ₁₁ O ₃₅ . It showed a two-phase mixing pattern. Chemical analysis of powder A revealed that the molar Cs/W ratio was 0.33. The composition ratios of other components are shown in Table 2. The XRD powder pattern in this case was a mixture of diffraction lines of both hexagonal Cs _0.32 WO ₃ and orthorhombic Cs ₄ W ₁₁ O ₃₅ , but the diffraction line of Cs ₄ W ₁₁ O ₃₅ was , a slight deviation from the ideal position and strength was observed. No data was found in the ICDD database that completely matched this diffraction pattern.

When this powder was observed under a transmission electron microscope (Hitachi High-Tech Corporation HF-2200), fine particles 40 as shown in FIG. 4(A) were observed. As shown in the selected area electron diffraction pattern of FIG. 4(B), the crystal of each fine particle was observed as a single-phase structure rather than a mixed structure in which two phases of hexagonal and orthorhombic crystals were separated. The electron diffraction image shown in FIG. 4(B) is a pattern corresponding to the [0001] crystal zone of a hexagonal crystal, and the diffraction spot shows a plane index when the crystal is considered to be a hexagonal crystal. When calculating the corresponding interplanar spacing from the closest diffraction spots in three directions, only the (01-10) interplanar spacing was 3.88 Å, which was significantly larger than the values in the other two directions, 3.48 Å and 3.43 Å. and deviated from exact hexagonal symmetry. Note that, in terms of crystallography, a negative index is indicated by a bar placed above the number, but for convenience of description, a minus sign is placed in front of the number in this specification.

On the other hand, FIG. 4(C) is an atomic image taken by the STEM-HAADF method (high-angle scattering dark field observation in scanning electron mode). In the HAADF method, the higher the atomic number and the higher the density of atoms in the projection direction, the brighter and stronger the atomic spot can be obtained, so when combined with the projection plane information of the [0001] crystal zone, the atomic species on the image can be identified. be done. The strongest spots in Figure 4(C) are W atoms, which are aligned along the (01-10) plane, and in a hexagonal crystal, they are aligned along the equivalent (1-100) or (10-10) plane. No similar arrangement can be seen. Since streaks are seen in the (01-10) spot direction in Figure 4(C), it can be seen that many planar defects (W, O defects) were inserted only on the (01-10) plane. It is interpreted that the spacing of the (01-10) plane has increased. Originally, in a hexagonal crystal, almost no defects are introduced on the (01-10), (1-100), and (10-10) planes that intersect at 60 degrees, and many defects are introduced only on the (01-10) plane. It can be seen that due to the insertion of a shaped defect, the hexagonal symmetry is lost and the crystal becomes orthorhombic. Due to the regular spots indicated by arrows 41 in FIG. 4(B), this W-deficient surface is introduced at a period approximately twice as large as 3.88 Å. As described above, this near-infrared absorbing particle was found to be a single crystal particle of cesium tungstate having a quasi-hexagonal crystal structure modulated into an orthorhombic crystal structure.

Furthermore, when the powder of near-infrared absorbing particles obtained was irradiated with 25W Al-Kα X-rays using X-ray photoelectron spectroscopy (XPS-Versa Probe II, manufactured by ULVAC-PHI) and the excited photoelectrons were observed, the result was 530.45 eV. It was found that the nearby O1s peak has a shoulder on the high energy side. The component around 532.80 eV was assumed to be caused by H ₂ O, and as a result of peak separation, it was found that a large amount of OH ₂ was contained. Furthermore, thermal desorption spectroscopy confirmed that OH and OH ₂ were discharged from the crystal in a temperature range of 500° C. to 700° C. during heating. These observation results indicate that OH and _OH2 are contained in the cesium tungstate of powder A, and considering the voids in the quasi-hexagonal crystals extending in the uniaxial direction, it is assumed that OH and OH2 have entered the window voids of the hexagonal tunnel. Guessed. It is thought that water and its decomposition products were introduced into the crystal by crystallization in superheated steam, but the H ⁺ and H ₃ O ⁺ ions generated at that time competed with positive W ions, causing It is thought that this may have led to some withdrawals.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)

20% by mass of the prepared powder A, 20% by mass of an acrylic polymer dispersant having an amine-containing group as a functional group (hereinafter abbreviated as "dispersant a"), and 60% by mass of methyl isobutyl ketone as a solvent. Weighed. These weighed materials were placed in a glass container together with silica beads having a diameter of 0.3 mm, and dispersed and pulverized for 1 hour using a paint shaker to obtain a dispersion liquid A.

25 parts by mass of dispersion liquid A and 75 parts by mass of a commercially available one-component type thermosetting ink containing an uncured thermosetting resin (manufactured by Teikoku Ink Mfg. Co., Ltd., MEG Screen Ink (Medium)) were mixed. A near-infrared curable ink composition (hereinafter referred to as ink A) according to Example 1 was prepared.

Ink A was applied onto a 3 mm thick blue plate glass using a bar coater (No. 10) to form a coating film (coating step).

Next, the coating film was irradiated with near-infrared rays to obtain a near-infrared cured film (hereinafter referred to as cured film A) (curing step).

In the curing process, a line heater HYP-14N (output 980 W) manufactured by Hybeck Co., Ltd. was used as a near-infrared irradiation source, and the heater was installed at a height of 5 cm from the coating surface of the coating film for 10 seconds. Near-infrared rays were irradiated.

The thickness of the obtained cured film A was 20 μm. It was confirmed visually that it was transparent.

The average particle size of the cesium tungsten oxide particles dispersed in the cured film A was calculated using an image processing device using a transmission electron microscope image, and was found to be 24 nm. The particle size of each particle is defined as the diameter of the circumscribed circle of the particle, and the above average particle size is calculated as the median diameter in the particle size distribution of the particle size of each particle measured for 100 particles.

The adhesion of cured film A was evaluated by the method shown below.

100 square-shaped cuts were made on the cured film A using a cutter guide with a gap of 1 mm. Then, a 18 mm wide tape (Cellotape (registered trademark) CT-18 manufactured by Nichiban Co., Ltd.) was pasted on the cut surface on the square, and a 2.0 kg roller was moved 20 times to ensure complete adhesion. It was peeled off rapidly at the peeling angle, and the number of squares that were peeled off was counted. The number of squares that came off was 0.

Even when the cured film A was irradiated with near-infrared rays for 20 seconds under the same conditions as for curing the near-infrared curable ink described above, the cured film did not melt again.

In addition, the spectral characteristics of the prepared cured film A were measured using a spectrophotometer manufactured by Hitachi, Ltd. based on the reflectance of light with a wavelength of 200 nm or more and 2100 nm or less, and the color index was calculated, L ^* = 88, a ^* = -1, b ^* = 8, and it was confirmed that the blue color was very weak and had a neutral tone.

The results are shown in Table 3. Table 3 also lists the results obtained in Examples 2 to 14, Comparative Example 1, and Comparative Example 2, which will be described later.
[Example 2]
(Production and evaluation of near-infrared absorbing particles)
The cesium tungsten oxide precursor powder produced in Example 1 was placed on an alumina boat, placed in a heating muffle furnace, and heated to 150° C. while flowing 100% by volume nitrogen gas. The gas to be supplied here is a gas containing superheated steam, hydrogen gas, and nitrogen gas in a volume ratio of 50:1:49 (as shown in Table 1, 1% H ₂ -49% N ₂ -50% superheated H ₂ O). The temperature was raised to 550° C. and held for 1 hour while flowing the mixed gas. This was directly cooled to room temperature to obtain a light blue powder B (first heat treatment step).

As shown in Figure 2, the X-ray powder diffraction pattern of this powder has broad diffraction lines, and the main phase is hexagonal Cs _0.32 WO ₃ , but also contains orthorhombic Cs ₄ W ₁₁ O ₃₅ and pyrochlore. Phase (Cs ₂ O) _0.44 W ₂ O A pattern was shown in which the diffraction lines of ₆ phases were mixed as different phases. The diffraction line of this pyrochlore phase was broad, and the reflection position was also slightly shifted. It is thought that O, OH, OH ₂ and OH ₃ derived from water were taken into the pyrochlore cavity. The (111) plane of the cubic pyrochlore phase is a plane with hexagonal symmetry similar to the bottom plane of a hexagonal crystal, and the pyrochlore cavity corresponds to a hexagonal cavity or a trigonal cavity in a hexagonal crystal. In other Examples as well, it was observed that the XRD powder pattern often contained a small amount of reflection of the pyrochlore phase.

When one particle of this powder was observed with a transmission electron microscope from the (0001) direction, it was found that the position of the prism surface spot appearing in the electron diffraction image was only one short and accompanied by a weak streak. Therefore, it was found that the hexagonal crystal is an orthorhombic crystal modulated by prismatic surface defects.

Chemical analysis of powder B showed Cs/W=0.32. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder B was used. The evaluation results are shown in Table 3.
[Example 3]
(Production and evaluation of near-infrared absorbing particles)
The light blue powder B obtained in Example 2 was spread on a carbon boat and held at 550° C. for 2 hours in an air flow of 1% by volume H ₂ -Ar. Next, the gas to be supplied was changed to 100% by volume nitrogen gas, and the temperature was held at 550°C for 0.5 hour while flowing nitrogen gas, and then the temperature was raised and held at 800°C for 1 hour. The temperature was lowered to room temperature to obtain a light blue powder C (second heat treatment step).

Chemical analysis of powder C revealed that the Cs/W ratio in terms of substance amount was 0.31. The composition ratios of other components are shown in Table 2.

As shown in FIG. 2, the X-ray powder diffraction pattern of powder C has broader diffraction lines compared to Examples 1 and 2, and has a hexagonal Cs _0.32 WO ₃ and an orthorhombic Cs ₄ W ₁₁ O ₃₅ The diffraction lines showed a mixed pattern. However, the diffraction line position and intensity of Cs ₄ W ₁₁ O ₃₅ did not completely match the ICDD data.

When one particle of this powder was observed with a transmission electron microscope from the (0001) direction, the position of the prism surface spot appearing in the electron diffraction image was only one short, and weak streaks were present. Therefore, it was found that the hexagonal crystal is an orthorhombic crystal modulated by prismatic surface defects.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder C was used. The evaluation results are shown in Table 3.
[Example 4]
(Production and evaluation of near-infrared absorbing particles)
The pale light blue powder B obtained in Example 2 was spread on a carbon boat, heated in an air flow of 100% by volume Ar, and held at 800° C. for 1 hour. Thereafter, the temperature was lowered to room temperature, and a light blue powder D was obtained.

The X-ray powder diffraction pattern of Powder D has broad diffraction lines as shown in FIG. 2, and shows a pattern in which diffraction lines of hexagonal Cs _0.32 WO ₃ and orthorhombic Cs ₄ W ₁₁ O ₃₅ are mixed. Ta. The diffraction line position and intensity of Cs ₄ W ₁₁ O ₃₅ did not completely match the ICDD data.

When one particle of this powder was observed with a transmission electron microscope from the (0001) direction, the position of the prism surface spot appearing in the electron diffraction image was only one short, and weak streaks were present. Therefore, it was found that the hexagonal crystal is an orthorhombic crystal modulated by prismatic surface defects.

Chemical analysis of powder D showed Cs/W=0.33. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder D was used. The evaluation results are shown in Table 3.
[Example 5]
(Production and evaluation of near-infrared absorbing particles)
The light blue powder B obtained in Example 2 was spread on a carbon boat, and the temperature was raised to 800° C. in an air flow of 100% by volume Ar. Here, the gas to be supplied was changed to 1% by volume H ₂ -Ar, and the temperature was maintained at 800° C. for 10 minutes in a flow of such gas. Thereafter, the temperature was lowered to room temperature, and a light blue powder E was obtained.

The X-ray powder diffraction pattern of powder E has broad diffraction lines as shown in FIG. 2, and shows a pattern in which diffraction lines of hexagonal Cs _0.32 WO ₃ and orthorhombic Cs ₄ W ₁₁ O ₃₅ are mixed. Ta. The diffraction line position and intensity of Cs ₄ W ₁₁ O ₃₅ did not completely match the ICDD data.

When one particle of this powder was observed with a transmission electron microscope from the (0001) direction, the position of the prism surface spot appearing in the electron diffraction image was only one short, and weak streaks were present. Therefore, it was found that the hexagonal crystal is an orthorhombic crystal modulated by prismatic surface defects.

Chemical analysis of powder E showed Cs/W=0.32. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder E was used. The evaluation results are shown in Table 3.
[Example 6]
(Production and evaluation of near-infrared absorbing particles)
The light blue powder B obtained in Example 2 was spread on a carbon boat and held at 500° C. for 30 minutes in an air flow of 1% by volume H ₂ -Ar. Next, the gas to be supplied was changed to 100% by volume nitrogen gas, and while flowing nitrogen gas, the temperature was held at 550°C for 30 minutes, and then the temperature was further raised and held at 800°C for 1 hour. Thereafter, the temperature was lowered to room temperature, and a light blue powder F was obtained.

The X-ray powder diffraction pattern of powder F has broad diffraction lines as shown in FIG. 2, and shows a pattern in which diffraction lines of hexagonal Cs _0.32 WO ₃ and orthorhombic Cs ₄ W ₁₁ O ₃₅ are mixed. Ta. The diffraction line position and intensity of Cs ₄ W ₁₁ O ₃₅ did not completely match the ICDD data.

When one particle of this powder was observed with a transmission electron microscope from the (0001) direction, the position of the prism surface spot appearing in the electron diffraction image was only one short, and weak streaks were present. Therefore, it was found that the hexagonal crystal is an orthorhombic crystal modulated by prismatic surface defects.

Chemical analysis of powder F showed Cs/W=0.31. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder F was used. The evaluation results are shown in Table 3.
[Example 7]
(Production and evaluation of near-infrared absorbing particles)
Cesium carbonate (Cs ₂ CO ₃ ) and tungsten trioxide (WO ₃ ) were weighed, mixed, and kneaded in a total amount of 20 g so that the molar ratio was Cs ₂ CO ₃ :WO ₃ =1:10, The obtained kneaded product was placed in a carbon boat and dried in the atmosphere at 110° C. for 12 hours. As a result, a cesium tungsten oxide precursor powder, which is a raw material for a compound containing Cs and W, was obtained.

Then, a first heat treatment step was performed under the same conditions as in Example 2 except that the cesium tungsten oxide precursor powder was used.

The powder obtained in the first heat treatment step was placed in a carbon boat, and the temperature was raised to 800° C. in a 100 volume % Ar gas flow. Then, the gas to be supplied was changed to a 1 volume % H ₂ -Ar gas flow, and the temperature was maintained at 800° C. for 10 minutes while flowing the gas, and then the temperature was lowered to room temperature to obtain a light blue powder G.

The X-ray powder diffraction pattern of powder G has broad diffraction lines, and is a mixture of the diffraction lines of hexagonal Cs _0.20 WO ₃ (ICDD0-083-1333) and orthorhombic Cs ₄ W ₁₁ O ₃₅ . Indicated. The diffraction line position and intensity of Cs ₄ W ₁₁ O ₃₅ did not completely match the ICDD data.

When one particle of this powder was observed with a transmission electron microscope from the (0001) direction, the position of the prism surface spot appearing in the electron diffraction image was only one short, and weak streaks were present. Therefore, the hexagonal crystal was identified as an orthorhombic crystal modulated by prismatic surface defects.

Chemical analysis of powder G showed Cs/W=0.20. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder G was used. The evaluation results are shown in Table 3.
[Example 8]
(Production and evaluation of near-infrared absorbing particles)
Cesium carbonate (Cs ₂ CO ₃ ) and tungsten trioxide (WO ₃ ) were weighed, mixed, and kneaded in a total amount of 20 g so that the molar ratio was Cs ₂ CO ₃ :WO ₃ =3:10, The obtained kneaded product was placed in a carbon boat and dried in the atmosphere at 110° C. for 12 hours. As a result, a cesium tungsten oxide precursor powder, which is a raw material for a compound containing Cs and W, was obtained.

Then, a first heat treatment step was performed under the same conditions as in Example 2 except that the cesium tungsten oxide precursor powder was used.

The powder obtained in the first heat treatment step was placed in a carbon boat, and the temperature was raised to 800° C. in a 100 volume % Ar gas flow. Then, the gas to be supplied was changed to 1% by volume H ₂ -Ar, and the temperature was kept at 800° C. for 10 minutes while flowing the gas, and then the temperature was lowered to room temperature to obtain a light blue powder H.

The X-ray powder diffraction pattern of Powder I has broad diffraction lines, and the main phases are rhombohedral Cs ₆ W ₁₁ O ₃₆ and Cs _8.5 W ₁₅ O ₄₈ , and hexagonal Cs _0.32 WO. The pattern showed a slight mixture of diffraction lines of ₃ and tetragonal Cs ₂ W ₃ O ₁₀ . However, the diffraction line positions and intensities of Cs ₆ W ₁₁ O ₃₆ and Cs _8.5 W ₁₅ O ₄₈ did not completely match the ICDD data.

When one particle of this powder was observed with a transmission electron microscope from the (0001) direction, differences in the positions of the prism surface spots appearing in the electron diffraction images were observed to exceed the experimental error range for all three. Therefore, it was found that the hexagonal crystal is mainly rhombohedral crystal modified by basal defects.

Chemical analysis of powder H showed Cs/W=0.59. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder H was used. The evaluation results are shown in Table 3.
[Example 9]
(Production and evaluation of near-infrared absorbing particles)
Cesium carbonate (Cs ₂ CO ₃ ) and tungsten trioxide (WO ₃ ) were weighed, mixed, and kneaded in a total amount of 20 g so that the molar ratio was Cs ₂ CO ₃ :WO ₃ =2:11, The obtained kneaded product was placed in a carbon boat and dried in the atmosphere at 110° C. for 12 hours. As a result, a cesium tungsten oxide precursor powder, which is a raw material for a compound containing Cs and W, was obtained.

Then, a first heat treatment step was performed under the same conditions as in Example 2, except that the cesium tungsten oxide precursor powder was used, and a light green powder I was obtained.

The X-ray powder diffraction pattern of Powder I has broad diffraction lines as shown in FIG. 3, and the main phase is a pyrochlore phase (Cs ₂ O) _0.44 W ₂ O ₆ , in which hexagonal Cs _{0. 32} WO ₃ and orthorhombic Cs ₄ W ₁₁ O ₃₅ diffraction lines showed a slightly mixed pattern. However, the diffraction line positions and intensities of (Cs ₂ O) _0.44 W ₂ O ₆ and Cs ₄ W ₁₁ O ₃₅ did not completely match the ICDD data.

When this powder was observed under a transmission electron microscope, a cubic electron diffraction pattern was obtained.

Chemical analysis of Powder I showed Cs/W=0.36. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder I was used. The evaluation results are shown in Table 3.
[Example 10]
(Production and evaluation of near-infrared absorbing particles)
Powder I produced in Example 9 was spread on a carbon boat, and the temperature was raised to 800° C. while flowing 100% by volume Ar gas. Then, the gas to be supplied was changed to 1% by volume H ₂ -Ar, and the temperature was kept at 800° C. for 10 minutes while flowing the gas, and then the temperature was lowered to room temperature to obtain a light blue powder J.

_The X _- ray powder diffraction _pattern of _this powder is _{as shown in FIG .} The diffraction lines of W ₁₅ O ₄₈ showed a mixed pattern. However, the diffraction line positions and intensities of Cs ₄ W ₁₁ O ₃₅ , Cs ₆ W ₁₁ O ₃₆ , and Cs _8.5 W ₁₅ O ₄₈ did not completely match the ICDD data.

When one particle of this powder was observed with a transmission electron microscope from the (0001) direction, differences in the positions of the prism surface spots appearing in the electron diffraction images were observed to exceed the experimental error range for all three. Therefore, it was found that the hexagonal crystal is mainly rhombohedral crystal modified by basal defects.

Chemical analysis of powder J showed Cs/W=0.36. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder J was used. The evaluation results are shown in Table 3.
[Example 11]
(Production and evaluation of near-infrared absorbing particles)
Powder I produced in Example 9 was spread on a carbon boat and held at 500° C. for 30 minutes in an air flow of 1% by volume H ₂ -Ar. Then, the gas to be supplied was changed to 100% by volume nitrogen gas, and the temperature was kept at 800° C. for 1 hour while flowing the nitrogen gas, and then the temperature was lowered to room temperature to obtain a light blue powder K.

_The X _- ray powder diffraction _pattern of _this powder is _{as shown in FIG .} The diffraction lines of W ₁₅ O ₄₈ showed a mixed pattern. However, the diffraction line positions and intensities of Cs ₄ W ₁₁ O ₃₅ , Cs ₆ W ₁₁ O ₃₆ , and Cs _8.5 W ₁₅ O ₄₈ did not completely match the ICDD data.

When one particle of this powder was observed with a transmission electron microscope from the (0001) direction, differences in the positions of the prism surface spots appearing in the electron diffraction images were observed to exceed the experimental error range for all three. Therefore, it was found that the hexagonal crystal is mainly rhombohedral crystal modified by basal defects.

Chemical analysis of powder K showed Cs/W=0.35. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder K was used. The evaluation results are shown in Table 3.
[Example 12]
(Production and evaluation of near-infrared absorbing particles)
Cesium carbonate (Cs ₂ CO ₃ ) and tungsten trioxide (WO ₃ ) were weighed, mixed, and kneaded in a total amount of 20 g so that the molar ratio was Cs ₂ CO ₃ :WO ₃ =1:5, The obtained kneaded product was placed in a carbon boat and dried in the atmosphere at 110° C. for 12 hours. As a result, a cesium tungsten oxide precursor powder, which is a raw material for a compound containing Cs and W, was obtained.

Then, the precursor powder was placed on an alumina boat, placed in a heating muffle furnace, and heated to 150° C. while flowing 100% by volume nitrogen gas. The gas supplied here was changed to a gas containing superheated steam, hydrogen gas, and nitrogen gas in a volume ratio of 50:1:49, and while flowing the mixed gas, the temperature was raised to 550° C. and held for 1 hour. This was directly cooled to room temperature to obtain a light blue powder L (first heat treatment step).

The X-ray powder diffraction pattern of powder L has broad diffraction lines as shown in FIG. 3, and the main phase is a pyrochlore phase (Cs ₂ O) _0.44 W ₂ O ₆ , in which hexagonal Cs _{0. 32} WO ₃ and orthorhombic Cs ₄ W ₁₁ O ₃₅ diffraction lines showed a slightly mixed pattern. However, the diffraction line positions and intensities of (Cs ₂ O) _0.44 W ₂ O ₆ and Cs ₄ W ₁₁ O ₃₅ did not completely match the ICDD data.

When this powder was observed under a transmission electron microscope, a cubic electron diffraction pattern was obtained.

Chemical analysis of powder L showed Cs/W=0.40. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder L was used. The evaluation results are shown in Table 3.
[Example 13]
(Production and evaluation of near-infrared absorbing particles)
Powder L produced in Example 12 was spread on a carbon boat, and the temperature was raised to 800° C. while flowing 100% by volume Ar gas. Then, the gas to be supplied was changed to 1% by volume H ₂ -Ar, and the temperature was kept at 800° C. for 10 minutes while flowing the gas, and then the temperature was lowered to room temperature to obtain a light blue powder M.

_The X _- ray powder diffraction _pattern of _this powder is _{as shown in FIG .} The diffraction lines of W ₁₅ O ₄₈ showed a mixed pattern. However, the diffraction line positions and intensities of Cs ₄ W ₁₁ O ₃₅ , Cs ₆ W ₁₁ O ₃₆ , and Cs _8.5 W ₁₅ O ₄₈ did not completely match the ICDD data.

When one particle of this powder was observed with a transmission electron microscope from the (0001) direction, differences in the positions of the prism surface spots appearing in the electron diffraction images were observed to exceed the experimental error range for all three. Therefore, it was found that the hexagonal crystal is mainly rhombohedral crystal modified by basal defects.

Chemical analysis of powder M showed Cs/W=0.42. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder M was used. The evaluation results are shown in Table 3.
[Example 14]
(Production and evaluation of near-infrared absorbing particles)
Powder L produced in Example 12 was spread on a carbon boat and held at 500° C. for 30 minutes in an air flow of 1% by volume H ₂ -Ar. Then, the gas to be supplied was changed to 100% by volume Ar, and the temperature was held at 550°C for 30 minutes while flowing the gas, then the temperature was further raised and held at 800°C for 1 hour, and then the temperature was lowered to room temperature, and light blue powder N I got it.

_The X- _ray powder diffraction _pattern of _this powder is _{as shown in FIG .} The diffraction lines of W ₁₅ O ₄₈ showed a mixed pattern. However, the diffraction line positions and intensities of Cs ₄ W ₁₁ O ₃₅ , Cs ₆ W ₁₁ O ₃₆ , and Cs _8.5 W ₁₅ O ₄₈ did not completely match the ICDD data.

When one particle of this powder was observed with a transmission electron microscope from the (0001) direction, differences in the positions of the prism surface spots appearing in the electron diffraction images were observed to exceed the experimental error range for all three. Therefore, it was found that the hexagonal crystal is mainly rhombohedral crystal modified by basal defects.

Chemical analysis of powder N showed Cs/W=0.42. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder N was used. The evaluation results are shown in Table 3.
[Comparative example 1]
(Production and evaluation of near-infrared absorbing particles)

The cesium tungsten oxide precursor powder obtained in Example 1 was placed in a carbon boat, heated to 850°C in a tube furnace in the atmosphere, held for 20 hours, cooled to room temperature, and pulverized and mixed using a crusher. did. Thereafter, it was heated again to 850° C. in the air, held for 20 hours, and then cooled to room temperature to obtain a very thin greenish white powder i. As shown in Fig. 2, the X-ray powder diffraction pattern of this powder i was identified as being mostly Cs ₄ W ₁₁ O ₃₅ single phase (ICDD 0-51-1891), although there was a slight amount of Cs ₆ W ₁₁ O ₃₆ mixed in. It was done. Chemical analysis of powder i showed Cs/W=0.36. The composition ratios of other components are shown in Table 2.
(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that Powder i was used. The evaluation results are shown in Table 3.
[Comparative example 2]

(Production and evaluation of near-infrared absorbing particles)
The cesium tungsten oxide precursor powder obtained in Example 1 was placed in a carbon boat and held at 550° C. for 2 hours under a stream of 1 vol% H ₂ gas using N ₂ gas as a carrier, and then 100 vol% N ₂ After changing to air flow and holding for 1 hour, the temperature was raised to 800°C, held for 1 hour, and slowly cooled to room temperature to obtain powder ii. The color of powder ii was dark blue. The X-ray powder diffraction pattern of this powder ii, as shown in FIG. 2, is identified as Cs _0.32 WO ₃ single phase (ICDD 0-81-1244), which is hexagonal cesium tungsten oxide. Chemical analysis of powder ii showed Cs/W=0.34. The composition ratios of other components are shown in Table 2.

(Manufacture and evaluation of near-infrared curable ink composition and cured film)
A near-infrared curable ink composition and a cured film were obtained and evaluated in the same manner as in Example 1 except that powder ii was used. The evaluation results are shown in Table 3.

実施例１～７で作製した粉末のＸＲＤ粉末パターンは、すべて六方晶Ｃｓ_０．３２ＷＯ_３と斜方晶Ｃｓ_４Ｗ_１１Ｏ_３５の混相パターンを示したが、回折線の強度比や位置はＩＣＤＤデータからのズレが観察され、不規則にプリズム面に面状欠陥が挿入された影響によると考えられる。（０００１）電子回折パターンはプリズム面スポットのひとつが面間隔の増加を伴い、斜方晶への結晶構造の変調が確認された。また実施例８～１４で作製した粉末のＸＲＤ粉末パターンには、すべて六方晶Ｃｓ_０．３２ＷＯ_３と菱面体晶Ｃｓ_６Ｗ_１１Ｏ_３６、Ｃｓ_８．５Ｗ_１５Ｏ_４８またはパイロクロア相（Ｃｓ_２Ｏ）_０．４４Ｗ_２Ｏ_６との混在が観察されたが、菱面体晶やパイロクロア相の回折線位置や強度分布はＩＣＤＤデータからのズレが見られた。（０００１）電子回折パターンはプリズム面スポット３種類とも面間隔の変化を伴い、菱面体晶への結晶構造の変調が確認された。またＸＲＤでパイロクロア相のパターンを同定した粉末では、立方晶の電子回折パターンが確認された。すなわち実施例１～１４で作製した粉末が含有するセシウムタングステン酸塩は、擬六方晶の結晶構造を有することが確認できた。

The XRD powder patterns of the powders prepared in Examples 1 to 7 all showed a mixed phase pattern of hexagonal Cs _0.32 WO ₃ and orthorhombic Cs ₄ W ₁₁ O ₃₅ , but the intensity ratio and position of the diffraction lines were different. A deviation from the ICDD data was observed, which is thought to be due to the irregular insertion of planar defects on the prism surface. In the (0001) electron diffraction pattern, one of the prism surface spots was accompanied by an increase in the interplanar spacing, and modulation of the crystal structure to orthorhombic crystal structure was confirmed. In addition, the XRD powder patterns of the powders prepared in Examples 8 to 14 all contain hexagonal Cs _0.32 WO ₃ and rhombohedral Cs ₆ W ₁₁ O ₃₆ , Cs _8.5 W ₁₅ O ₄₈ or pyrochlore phase (Cs ₂ O) _0.44 W ₂ O ₆ was observed, but the diffraction line positions and intensity distributions of the rhombohedral and pyrochlore phases deviated from the ICDD data. The (0001) electron diffraction pattern was accompanied by a change in the interplanar spacing for all three types of prism surface spots, and a modulation of the crystal structure to a rhombohedral crystal structure was confirmed. Furthermore, in the powder whose pyrochlore phase pattern was identified by XRD, a cubic electron diffraction pattern was confirmed. That is, it was confirmed that the cesium tungstate contained in the powders produced in Examples 1 to 14 had a pseudohexagonal crystal structure.

All of the cured films using the near-infrared curable ink compositions prepared in Examples 1 to 14 containing near-infrared absorbing particles containing cesium tungstate satisfying a predetermined composition had color tone b ^* . It was confirmed that there was a relationship of b ^* ≧0, and the blue color was very weak and had a neutral tone. That is, it was confirmed that the cured films of these Examples contained near-infrared absorbing particles containing composite tungsten oxide, and could have a more neutral color tone.

On the other hand, the near-infrared absorbing particles contained in the cured films of Comparative Examples 1 and 2 do not contain cesium tungsten oxide that satisfies the predetermined composition.

Although the cured film using the near-infrared curable ink composition prepared in Comparative Example 1 exhibited a neutral color tone, the number of peeled squares was as large as 25, and it was confirmed that the adhesiveness was poor. This is considered to be because the near-infrared absorbing particles contained in the near-infrared curable ink composition used in Comparative Example 1 have a low solar absorption rate.

Further, it can be seen that the cured film using the near-near infrared curable ink composition prepared in Comparative Example 2 has a color tone b ^* of b ^* <0, and a bluish tinge is clearly recognized. In other words, it was confirmed that the cured film of Comparative Example 2 could not have a neutral color tone.

10 Three-element composition diagram 11, 16 Regions 12 to 15 Straight line 40 Fine particles 41 Arrows 50, 61 Near-infrared absorbing particles 50A Surface 51 Coating 60 Near-infrared curable ink composition 62 Resin component

Claims (13)

a thermosetting resin or a thermoplastic resin;
Near-infrared absorbing particles;
The near-infrared absorbing particles contain cesium tungstate,
The cesium tungstate has a pseudohexagonal crystal structure modulated into one or more types selected from orthorhombic, rhombohedral, and cubic,
The cesium tungstate is represented by the general formula Cs _x W _y O _z , and in the ternary composition diagram with Cs, W, and O as the vertices, x = 0.6y, z = 2.5y, y =5x, and a near-infrared curable ink composition having a composition within a region surrounded by four straight lines: Cs ₂ O: WO ₃ = m: n (m and n are integers). The near-infrared curable ink composition according to claim 1, wherein the cesium tungstate contains one or more types of additive components selected from O, OH, _OH2 , and _OH3 . The near-infrared curing method according to claim 2, wherein the additive component is present in one or more positions selected from a hexagonal window, a hexagonal cavity, and a trigonal cavity formed by the WO ₆ octahedron of the cesium tungstate crystal. type ink composition. There is a defect in a part of one or more elements selected from Cs and W constituting the crystal of the cesium tungstate,
The near-infrared curable type according to any one of claims 1 to 3, wherein x and y in the general formula Cs _x W _y O _z have a relationship of 0.2≦x/y≦0.6. Ink composition. The near-infrared curable ink composition according to any one of claims 1 to 4, wherein a portion of O in the WO ₆ octahedron constituting the crystal of the cesium tungstate has defects. A part of Cs in the cesium tungstate is replaced by an additive element, and the additive element is one type selected from Na, Tl, In, Li, Be, Mg, Ca, Sr, Ba, Al, and Ga. The near-infrared curable ink composition according to any one of claims 1 to 5, which is the above. The near-infrared curable ink composition according to any one of claims 1 to 6, wherein the near-infrared absorbing particles have an average particle size of 0.1 nm or more and 200 nm or less. The surface of the near-infrared absorbing particles is coated with a compound containing one or more types of atoms selected from Si, Ti, Zr, Al, and Zn. near-infrared curable ink composition. The near-infrared curable ink composition according to any one of claims 1 to 8, further comprising one or more selected from organic pigments, inorganic pigments, and dyes. The near-infrared curable ink composition according to any one of claims 1 to 8, further comprising a dispersant. The near-infrared curable ink composition according to any one of claims 1 to 10, further comprising a solvent. A near-infrared cured film that is a cured product of the near-infrared curable ink composition according to any one of claims 1 to 11. A coating step of coating the near-infrared curable ink composition according to any one of claims 1 to 11 on a substrate to form a coating film;
A method for producing a near-infrared cured product, comprising a curing step of curing the near-infrared curable ink composition by irradiating the coating film with near-infrared rays.

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