Infrared-curable ink composition, infrared-cured product, and method for producing infrared-cured product

Abstract

Provided is an infrared curable ink composition which contains infrared absorbing particles and a thermosetting resin, wherein the infrared absorbing particles contain particles of a composite tungsten oxide that is represented by general formula MxWyOz (wherein the element M represents one or more elements that are selected from among H, He, an alkali metal, an alkaline earth metal, a rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi and I; W represents tungsten; O represents oxygen; 0.001 ≤ x / y ≤ 1; and 3.0 < z / y).

Description

[Technical Field]

[0001] The present invention relates to an infrared-curable ink composition, an infrared-cured product, and a method for producing the infrared-cured product. [Background technology]

[0002] In recent years, ultraviolet-curable paints, which are cured using ultraviolet light, are widely known as environmentally friendly paints that are excellent in reducing CO2 emissions because they can be printed without heating (Patent Document 1).

[0003] However, when a composition that undergoes radical polymerization upon irradiation with ultraviolet light is used as a UV-curable ink or paint, the polymerization (curing) is inhibited in the presence of oxygen. Furthermore, when a composition that undergoes cationic polymerization upon irradiation with ultraviolet light is used, there is a problem that a strong acid is generated during the polymerization. Furthermore, UV absorbers are generally used to improve the light resistance of printed or coated surfaces formed by applying UV-curable ink or paint, but when UV absorbers are used in UV-curable ink or paint, there is a problem that curing by UV irradiation is inhibited.

[0004] In order to solve these problems, Patent Documents 2 and 3 propose infrared-curable compositions that are cured by irradiation with infrared rays rather than ultraviolet rays.

[0005] Patent Document 2 discloses a technique using an organic infrared absorbent such as a cyanine dye, and Patent Document 3 discloses a technique using a copper salt of phosphonic acid as an infrared absorbent. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2012-140516 [Patent Document 2] Japanese Patent Application Publication No. 2008-214576 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-131928

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, all of the infrared curable compositions disclosed in Patent Documents 2 and 3 have a problem that their infrared absorption characteristics are not sufficient, and an infrared curable composition having excellent infrared absorption characteristics has been demanded.

[0008] In addition, the infrared curable composition has been demanded to have excellent long-term storage stability for various applications.

[0009] One aspect of the present invention aims to provide an infrared curable ink composition excellent in infrared absorption characteristics and long-term storage stability.

Means for Solving the Problems

[0010] One aspect of the present invention includes infrared absorption particles and a thermosetting resin, where the infrared absorption particles are represented by the general formula M x W y O z (The M element is one or more elements selected from H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I; W is tungsten; O is oxygen; and 0.001 ≦ x / y ≦ 1, 3.0 < z / y), and provides an infrared curable ink composition containing particles of a composite tungsten oxide.

Effects of the Invention

[0011] One aspect of the present invention can provide an infrared curable ink composition excellent in infrared absorption characteristics and long-term storage stability.

Brief Description of the Drawings

[0012] [Figure 1] Figure 1 is an explanatory diagram of a hybrid plasma reactor in which a DC plasma and a high-frequency plasma are superimposed. [Figure 2] Figure 2 is an explanatory diagram of a high-frequency plasma reactor. [Figure 3] Figure 3 is a diagram schematically showing the infrared-curable ink composition according to the present embodiment.

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments for carrying out the present invention will be described. However, the present invention is not limited to the following embodiments, and various modifications and substitutions can be made to the following embodiments without departing from the scope of the present invention.

[0014] The infrared-curable ink composition of the present embodiment (hereinafter, also referred to as "ink composition") can contain infrared-absorbing particles and a thermosetting resin. Note that the infrared-curable ink composition of the present embodiment can also be composed only of infrared-absorbing particles and a thermosetting resin, but in this case, it does not exclude containing inevitable impurities.

[0015] And the infrared-absorbing particles can contain particles of a composite tungsten oxide represented by the general formula M x W y O z (The M element is one or more elements selected from H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I, W is tungsten, O is oxygen, and 0.001 ≦ x / y ≦ 1, 3.0 < z / y).

[0016] The present inventors conducted research into infrared-curable ink compositions with excellent infrared absorption properties and long-term storage stability. As a result, they found that an infrared-curable ink composition containing composite tungsten oxide particles having a predetermined composition as infrared-absorbing particles has excellent infrared absorption properties because the composite tungsten oxide has excellent infrared absorption properties, leading to the completion of the present invention. With this infrared-curable ink composition, the infrared-absorbing particles can efficiently cure a thermosetting resin by utilizing the heat generated when they absorb infrared rays, particularly near-infrared rays.

[0017] Furthermore, an infrared-curable ink composition in which the infrared-absorbing particles contain composite tungsten oxide particles having a predetermined composition also has excellent transparency and long-term storage stability.

[0018] Before describing the infrared curable ink composition of this embodiment, infrared absorbing particles that can be suitably used in the infrared curable ink composition of this embodiment and a method for producing the infrared absorbing particles will be described. [Infrared absorbing particles] (1) Composition, crystal structure As infrared absorbing particles to be used in the ink composition of this embodiment, the inventors of the present invention have investigated composite tungsten oxide particles, carbon black powder, and tin-doped indium oxide (ITO) powder.

[0019] However, when carbon black powder is used, there are problems in that the transparency of the ink composition is reduced because the carbon black powder is black, and further the freedom of color selection is reduced.

[0020] On the other hand, if a large amount of ITO powder is not added, the ink composition will not exhibit its curability. However, if a large amount is added, the added ITO powder can affect the transparency and color tone of the ink composition.

[0021] Therefore, the infrared curable ink composition of this embodiment contains infrared absorbing particles represented by the general formula M x W y Oz It can contain particles of a composite tungsten oxide represented by

[0022] In the general formula, the M element is one or more elements selected from H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I. W is tungsten and O is oxygen. x, y, z can satisfy 0.001 ≦ x / y ≦ 1 and 3.0 < z / y.

[0023] Generally, a material containing free electrons is known to exhibit a reflection absorption response due to plasma vibration with respect to electromagnetic waves having wavelengths from 200 nm to 2600 nm around the region of sunlight. And when the powder of the material containing the free electrons is made into particles smaller than the wavelength of light, it is known that geometric scattering in the visible light region (wavelength 380 nm or more and 780 nm or less) is reduced and transparency in the visible light region is obtained. In this specification, "transparency" is used to mean that there is little scattering and high transmittance with respect to light in the visible light region.

[0024] General formula WO 3-a Tungsten oxides represented by and so-called tungsten bronzes obtained by adding a positive element such as Na to tungsten trioxide are known to be conductive materials and materials containing free electrons. And these materials suggest the response of free electrons to light in the near-infrared region by analysis such as single crystals.

[0025] Generally, since there are no effective free electrons in tungsten trioxide (WO3), it has few absorption and reflection characteristics in the infrared region and is not effective as an infrared absorption material. Here, it is known that free electrons are generated in the tungsten oxide by reducing the ratio of oxygen to tungsten in tungsten trioxide to less than 3.

[0026] In addition, it has conventionally been done to add an M element to the tungsten oxide to obtain a composite tungsten oxide. Due to this configuration, free electrons are generated in the composite tungsten oxide, absorption characteristics derived from the free electrons are exhibited in the near-infrared region, and it is effective as an infrared absorption material near a wavelength of 1000 nm.

[0027] In order to obtain infrared absorption particles with excellent long-term storage stability, the inventors of the present invention conducted further research on tungsten oxide and composite tungsten oxide. As a result, in infrared absorption particles containing particles of a composite tungsten oxide represented by the general formula M x W y O z it was found that by setting 3.0 < z / y with respect to y and z in the above general formula, both infrared absorption characteristics and long-term storage stability can be achieved. In this specification, long-term storage stability means that for infrared absorption particles and the like, even when placed in a room temperature environment for a long period, for example, for 3 months, excellent infrared absorption characteristics can be obtained. For example, in the case of an ink composition, it can absorb infrared rays and supply the amount of heat required to cure the thermosetting resin.

[0028] The infrared absorption particles used in the ink composition of this embodiment can contain particles of a composite tungsten oxide represented by the general formula M x W y O z as described above. The above infrared absorption particles can also be composed of particles of a composite tungsten oxide represented by the above general formula. However, even in this case, it does not exclude containing unavoidable components mixed in during the manufacturing process or the like.

[0029] Here, as described above, from the viewpoint of enhancing stability, the M element in the above general formula is preferably one or more elements selected from H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I. From the viewpoint of particularly improving the optical properties and long-term storage stability of the infrared absorbing particles, the M element is more preferably an alkali metal, alkaline earth metal element, transition metal element, Group 4B element, or Group 5B element.

[0030] When the composite tungsten oxide contains crystals having a hexagonal crystal structure, the transmittance of the particles in the visible light region is particularly improved, and the absorption in the near-infrared region is particularly improved. Therefore, it is preferable that the composite tungsten oxide has a hexagonal crystal structure. The hexagonal crystal structure is formed by a group of six octahedra formed by WO6 units, forming hexagonal voids (tunnels), and an M element is placed in the void to form one unit, and this single unit is formed by a group of many such units.

[0031] It should be noted that the composite tungsten oxide is not limited to the case where it contains crystals having a hexagonal crystal structure, but for example, if it has a structure in which six octahedra formed by the above-mentioned unit structure, that is, WO6 units, are assembled to form hexagonal voids, and the M element is arranged in the voids, it can particularly improve the transmittance in the visible light region and particularly improve the absorption in the near-infrared region.For this reason, even if the composite tungsten oxide does not contain crystals having a hexagonal crystal structure and only has the above-mentioned unit structure, it can obtain a high effect.

[0032] As described above, when a composite tungsten oxide contains a structure in which cations of an M element are added to hexagonal voids, absorption in the near-infrared region is particularly improved. Generally, when an M element with a large ionic radius is added, a hexagonal crystal or the above structure is easily formed. Specifically, when the composite tungsten oxide contains one or more elements selected from Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn as the M element, the hexagonal crystal or the above structure is easily formed. Therefore, the M element preferably contains one or more elements selected from Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn, and more preferably, the M element is one or more elements selected from Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn.

[0033] Furthermore, among these M elements having a large ionic radius, particles of a composite tungsten oxide containing one or more elements selected from Cs and Rb are likely to form hexagonal crystals or the above-mentioned structure, and can achieve both absorption in the near-infrared region and transmission in the visible light region, while also exhibiting particularly high performance.

[0034] When particles of a composite tungsten oxide having a hexagonal crystal structure have a uniform crystal structure, x / y, which indicates the content ratio of element M to 1 mole of tungsten in the general formula described above, is preferably 0.2 or more and 0.5 or less, and more preferably 0.33. When the value of x / y is 0.33, it is thought that element M is arranged in all of the hexagonal voids.

[0035] The composite tungsten oxide is also effective as an infrared absorbing material when it contains crystals other than the above-mentioned hexagonal crystals, such as tetragonal crystals or cubic crystals.

[0036] The cubic and tetragonal composite tungsten oxides each have a suitable range and upper limit of the amount of element M added, which is derived from their structures, and the upper limit of x / y, which is the content ratio of M element to 1 mole of tungsten, is 1 mole in the case of a cubic crystal, and about 0.5 moles in the case of a tetragonal crystal. Note that the upper limit of x / y, which is the content ratio of M element to 1 mole of tungsten, varies depending on the type of M element, etc., but in the case of a tetragonal crystal, about 0.5 moles is easy to industrially produce.

[0037] However, it is difficult to simply define these structures, and the ranges are examples showing particularly basic ranges, so the present invention is not limited to these.

[0038] Depending on the crystal structure contained in the composite tungsten oxide, the absorption position in the near-infrared region tends to change. The absorption position in the near-infrared region tends to shift toward longer wavelengths in tetragonal crystals compared to cubic crystals, and furthermore, in hexagonal crystals, it tends to shift toward longer wavelengths compared to tetragonal crystals. Furthermore, accompanying this shift in absorption position, absorption in the visible light region is lowest in hexagonal crystals, followed by tetragonal crystals, with cubic crystals having the highest absorption. Therefore, it is preferable to select the crystal system contained depending on the required performance, etc. For example, when used in an application requiring greater transmission of light in the visible region and greater absorption of light in the near-infrared region, it is preferable that the composite tungsten oxide particles contain hexagonal crystals. In particular, the infrared-curable ink composition can also contain pigments, dyes, etc. as described below. However, in order to avoid interfering with the color development of the pigments, etc., it is preferable that the composition transmits light in the visible region while absorbing light in the near-infrared region.

[0039] By combining the above-mentioned control of the oxygen content with the addition of an element M that generates free electrons to a composite tungsten oxide, it is possible to obtain an infrared absorbing material that is more efficient and has excellent long-term storage properties. The general formula of the composite tungsten oxide, which is an infrared absorbing material that combines the control of the oxygen content and the addition of an element M that generates free electrons, is x W y O zWhen described as such, x and y can be 0.001 ≦ x / y ≦ 1, and preferably satisfy 0.20 ≦ x / y ≦ 0.37.

[0040] Also, for y and z in the above general formula, the relationship 3.0 < z / y is satisfied, preferably 3.0 < z / y < 3.4 is satisfied, more preferably 3.0 < z / y < 3.3 is satisfied, and even more preferably 3.0 < z / y < 3.22 is satisfied.

[0041] It is considered that when the composite tungsten oxide having a hexagonal crystal structure has z / y = 3, the value of x / y becomes 0.33, and the element M is arranged in all of the hexagonal voids.

[0042] It has been confirmed by chemical analysis that the composite tungsten oxide contained in the infrared absorption particles according to the present embodiment has z / y exceeding 3. On the other hand, it has been confirmed by powder X-ray diffraction that the composite tungsten oxide contained in the infrared absorption particles according to the present embodiment may take at least one of a tetragonal, cubic, and hexagonal tungsten bronze structure when z / y = 3. Therefore, it is preferable that the particles of the composite tungsten oxide contained in the infrared absorption particles according to the present embodiment contain crystals having one or more crystal structures selected from hexagonal, tetragonal, and cubic crystals. By containing the crystals of the above crystal structure, particularly excellent near-infrared absorption characteristics and visible light transmission characteristics can be exhibited.

[0043] By the way, it is considered that oxygen atoms when the z / y value exceeds 3 penetrate into the crystals of the composite tungsten oxide particles. As a result, by oxygen atoms penetrating into the crystals, it is considered that excellent long-term storage stability can be realized without the crystals of the composite tungsten oxide particles being deteriorated even when exposed to heat or moisture.

[0044] The crystal structure of the crystals contained in the particles of the composite tungsten oxide contained in the infrared absorption particles according to the present embodiment can be confirmed by an X-ray diffraction pattern by the powder X-ray diffraction method (θ-2θ method).

[0045] The infrared absorbing particles of this embodiment exhibit light transmission characteristics having a maximum value in a wavelength range of 350 nm or more and 600 nm or less and a minimum value in a wavelength range of 800 nm or more and 2100 nm or less, and can exhibit excellent near-infrared absorption effects and long-term storage stability. It is more preferable that the infrared absorbing particles of this embodiment exhibit light transmission characteristics having a maximum value in a wavelength range of 440 nm or more and 600 nm or less and a minimum value in a wavelength range of 1150 nm or more and 2100 nm or less. (2) Lattice constant The general formula of the composite tungsten oxide contained in the composite tungsten oxide particles is M as described above. x W y O z When the M element contains one or more elements selected from Cs and Rb and the composite tungsten oxide has a hexagonal crystal structure, the lattice constant of the composite tungsten oxide is preferably 7.3850 Å or more and 7.4186 Å or less for the a-axis and 7.5600 Å or more and 7.6240 Å or less for the c-axis. By setting the above lattice constants for the composite tungsten oxide, particularly excellent properties can be achieved in terms of near-infrared absorption characteristics and long-term storage stability. In the above case, it is more preferable that the M element consists of one or more elements selected from Cs and Rb. The above lattice constant can be calculated using the Rietveld method. (3) Particle size The infrared absorbing particles according to this embodiment preferably have a particle diameter of 100 nm or less. From the viewpoint of exhibiting better near-infrared absorbing properties, the particle diameter is more preferably 10 nm or more and 100 nm or less, even more preferably 10 nm or more and 80 nm or less, particularly preferably 10 nm or more and 60 nm or less, and most preferably 10 nm or more and 40 nm or less. When the particle diameter of the infrared absorbing particles is in the range of 10 nm or more and 40 nm or less, the best near-infrared absorbing properties are exhibited.

[0046] Here, the particle size refers to the size of individual infrared absorbing particles that are not aggregated, that is, the particle size of individual particles.

[0047] The particle size here does not include the size of aggregates of infrared absorbing particles, and is different from the dispersed particle size.

[0048] The particle size here can be calculated by, for example, measuring the particle sizes of multiple particles using a transmission electron microscope (TEM) or the like while the infrared absorbing particles are dispersed. Since infrared absorbing particles are usually irregular in shape, the diameter of the smallest circle circumscribing the particle can be used as the particle size of the particle. For example, when the particle sizes of multiple particles are measured for each particle using a transmission electron microscope as described above, it is preferable that the particle sizes of all particles satisfy the above range. The number of particles to be measured is not particularly limited, but is preferably 10 to 50, for example. (4) Crystallite size Furthermore, from the viewpoint of exhibiting excellent near-infrared absorbing properties, the crystallite diameter of the composite tungsten oxide is preferably 10 nm or more and 100 nm or less, more preferably 10 nm or more and 80 nm or less, even more preferably 10 nm or more and 60 nm or less, and particularly preferably 10 nm or more and 40 nm or less. This is because, if the crystallite diameter is in the range of 10 nm or more and 40 nm or less, particularly excellent near-infrared absorbing properties are exhibited. The crystallite diameter of the composite tungsten oxide particles contained in the infrared absorbing particles can be calculated using the Rietveld method from the X-ray diffraction pattern measured by powder X-ray diffractometry (θ-2θ method). (5)Dispersed particle size Furthermore, since an infrared-cured product that is an infrared-absorbing particle dispersion containing particles of the composite tungsten oxide according to this embodiment significantly absorbs light in the near-infrared region, particularly light with a wavelength around 1000 nm, the transmitted color tone is often blue to green.

[0049] The dispersed particle diameter of the infrared absorbing particles of this embodiment can be selected depending on the intended use. First, when used in an application that requires maintaining transparency, the infrared absorbing particles preferably have a dispersed particle diameter of 800 nm or less. This is because particles with a dispersed particle diameter of 800 nm or less do not completely block light due to scattering, and can maintain visibility in the visible light range while efficiently maintaining transparency.

[0050] In particular, when transparency in the visible light region is important, it is preferable to further consider scattering by particles. Note that the dispersed particle size includes the size of aggregates of infrared absorbing particles and is different from the particle size described above.

[0051] When emphasis is placed on reducing scattering by the particles, the dispersed particle diameter of the infrared-absorbing particles of this embodiment is preferably 200 nm or less, more preferably 1 nm or more to 200 nm or less, and even more preferably 1 nm or more to 100 nm or less. This is because a small dispersed particle diameter reduces scattering of light in the visible light region with wavelengths of 380 nm or more to 780 nm or less due to geometric scattering or Mie scattering, thereby preventing the infrared-cured product, which is a dispersion containing the infrared-absorbing particles of this embodiment, from becoming like frosted glass and losing clear transparency. That is, when the dispersed particle diameter is 200 nm or less, the geometric scattering or Mie scattering is reduced, resulting in the Rayleigh scattering region. In the Rayleigh scattering region, scattered light is proportional to the sixth power of the dispersed particle diameter, so scattering decreases with decreasing dispersed particle diameter, improving transparency. Furthermore, a dispersed particle diameter of 100 nm or less is preferable because scattered light is significantly reduced. From the viewpoint of avoiding light scattering, a smaller dispersed particle size is preferable, but from the viewpoint of industrial productivity, the dispersed particle size of the infrared absorbing particles is preferably 1 nm or more, and more preferably 10 nm or more.

[0052] By setting the dispersed particle diameter to 800 nm or less, the haze (haze value) of the infrared-cured product, which is an infrared-absorbing particle dispersion in which infrared-absorbing particles are dispersed in a medium, can be set to 10% or less at a visible light transmittance of 85% or less. In particular, by setting the dispersed particle diameter to 100 nm or less, the haze can be set to 1% or less. (6) Covering The surface of the infrared absorbing particles may be coated with a compound containing one or more elements selected from Si, Ti, Zr, and Al. By coating the surface of the infrared absorbing particles with the compound, weather resistance can be particularly improved.

[0053] The compound containing one or more elements selected from Si, Ti, Zr, and Al can be one or more selected from the group consisting of hydrolysis products of metal chelate compounds containing Si, Ti, Zr, and Al, polymers of hydrolysis products of metal chelate compounds, hydrolysis products of metal cyclic oligomer compounds, and polymers of hydrolysis products of metal cyclic oligomer compounds. The metal chelate compounds and metal cyclic oligomer compounds are preferably metal alkoxides, metal acetylacetonates, and metal carboxylates, and therefore preferably have one or more groups selected from ether bonds, ester bonds, alkoxy groups, and acetyl groups.

[0054] The operation of coating the surfaces of the infrared absorbing particles with these compounds is preferably carried out before preparing an infrared absorbing particle dispersion or an infrared curable ink composition. [Method of manufacturing infrared absorbing particles] A configuration example of the method for producing infrared absorbing particles will be described. According to the method for producing infrared absorbing particles of this embodiment, the infrared absorbing particles described above can be produced. Therefore, some of the matters already described will not be described again.

[0055] The infrared absorbing particles of this embodiment contain the compound represented by the general formula M x W y O z The composite tungsten oxide particles represented by the formula (I) can be produced by, for example, the following solid-state reaction method or plasma method.

[0056] Each method will be explained below. (1) Solid-state reaction method When composite tungsten oxide particles are produced by a solid-state reaction method, the following steps may be included.

[0057] A tungsten compound and an M element compound are mixed to prepare a raw material mixture (mixing step). Preferably, the raw material mixture is blended and mixed so that the molar ratio of the M element to tungsten in the raw material mixture is the ratio of x to y in the above general formula of the target composite tungsten oxide particles.

[0058] The raw material mixture obtained in the mixing step is heat-treated in an atmosphere containing oxygen (first heat treatment step).

[0059] The heat-treated product obtained after the first heat treatment step is heat-treated in a reducing gas atmosphere, a mixed gas atmosphere of a reducing gas and an inert gas, or an inert gas atmosphere (second heat treatment step).

[0060] After the second heat treatment step, if necessary, the infrared absorbing particles may be subjected to a pulverization treatment or the like so as to have a desired particle size.

[0061] The infrared absorbing particles of the present embodiment, including the composite tungsten oxide particles obtained by the above steps, have sufficient near-infrared absorbing power and have properties preferred as infrared absorbing particles. In addition, the infrared absorbing particles can be excellent in long-term storage stability.

[0062] Each step will be described in detail below. (Mixing process) The tungsten compound to be subjected to the mixing step can be one or more compounds selected from the group consisting of tungsten acid (H2WO4), ammonium tungstate, tungsten hexachloride, and tungsten hydrate obtained by adding water to tungsten hexachloride dissolved in alcohol to hydrolyze it, and then evaporating the solvent.

[0063] The M element compound to be subjected to the mixing step may be, for example, one or more selected from oxides, hydroxides, nitrates, sulfates, chlorides, and carbonates of the M element.

[0064] In the mixing step, when mixing the tungsten compound and the M element compound, the mass ratio (M:W) of the M element (M) to tungsten (W) in the resulting raw material mixture is adjusted to satisfy the target general formula M x W y O z It is preferable to mix the raw materials so that x:y is equal to the above.

[0065] The mixing method is not particularly limited, and either wet mixing or dry mixing can be used. In the case of wet mixing, a mixed powder of the M element compound and the tungsten compound is obtained by drying the mixture obtained after wet mixing. The drying temperature and time after wet mixing are not particularly limited.

[0066] The dry mixing may be carried out using a known mixing device such as a commercially available crusher, kneader, ball mill, sand mill, or paint shaker, and there are no particular limitations on the mixing conditions such as the mixing time and mixing speed. (First heat treatment step) The heat treatment temperature in the first heat treatment step is not particularly limited, but is preferably higher than the temperature at which the composite tungsten oxide particles crystallize, specifically, for example, 500°C or higher and 1000°C or lower, and more preferably 500°C or higher and 800°C or lower. (Second heat treatment process) In the second heat treatment step, as described above, heat treatment can be performed in a reducing gas atmosphere, a mixed gas atmosphere of a reducing gas and an inert gas, or an inert gas atmosphere at a temperature of 500°C or higher and 1200°C or lower.

[0067] When a reducing gas is used in the second heat treatment step, the type of reducing gas is not particularly limited, but hydrogen (H2) is preferred. Furthermore, when hydrogen is used as the reducing gas, its concentration is not particularly limited and can be appropriately selected depending on the firing temperature, the amount of the starting materials, etc. For example, it is 20 vol% or less, preferably 10 vol% or less, and more preferably 7 vol% or less. A reducing gas concentration of 20 vol% or less can avoid the formation of WO2, which does not have solar radiation shielding properties, due to rapid reduction. (2) Plasma method The infrared absorbing particles of this embodiment contain the compound represented by the general formula M x W y O z The composite tungsten oxide particles represented by the formula (I) can also be produced by, for example, a plasma method. When producing infrared absorbing particles by a plasma method, the following steps can be included.

[0068] As a starting material, a raw material mixture of a tungsten compound and an M element compound, or a composite tungsten oxide precursor represented by the general formula M x W y O z´ is prepared (raw material preparation step).

[0069] The starting material prepared in the raw material preparation step is supplied into the plasma together with a carrier gas, and through an evaporation and condensation process, the target composite tungsten oxide particles are generated (reaction step).

[0070] Hereinafter, each step will be described in detail. (Raw material preparation step) When preparing a raw material mixture of a tungsten compound and an M element compound as a starting material, it is preferable to blend and mix each raw material so that the molar ratio (M:W) of the M element (M) to the tungsten (W) in the raw material mixture of the tungsten compound and the M element compound is equal to the ratio x:y of x to y in the above-mentioned general formula of the target composite tungsten oxide.

[0071] As the tungsten compound and the M element compound, the same materials as those described in the solid-phase reaction method can be preferably used, and thus the description is omitted here.

[0072] In addition, in the composite tungsten oxide precursor represented by the general formula M x W y O[[ID=3"1]] z´ M can be the above-mentioned M element, W can be tungsten, and O can be oxygen, and it is preferable that x, y, and z´ satisfy 0.001 ≤ x / y ≤ 1 and 2.0 < z´ / y.

[0073] In the composite tungsten oxide precursor represented by the general formula M x W y [[ID=4o]]O z´ For example, it can be synthesized by the above-mentioned solid-phase reaction method. The x / y in such a composite tungsten oxide precursor is the same as that in the target general formula M x W y O zIt is preferable that the material be one that matches x / y in the composite tungsten oxide particles represented by the formula: (Reaction step) A mixed gas of an inert gas and oxygen gas can be used as a carrier gas for transporting the starting materials in the reaction step.

[0074] The plasma can be generated, for example, in an atmosphere of an inert gas alone or a mixed gas of an inert gas and hydrogen gas. The plasma is not particularly limited, but thermal plasma is preferred. The raw material supplied into the plasma instantly evaporates, and the evaporated raw material condenses as it reaches the plasma tail flame. It is then rapidly cooled and solidified outside the plasma flame, producing composite tungsten oxide particles. The plasma method can produce, for example, composite tungsten oxide particles with a single crystalline phase.

[0075] The plasma used in the method for producing infrared absorbing particles of this embodiment is preferably, for example, any one of DC arc plasma, high frequency plasma, microwave plasma, low frequency AC plasma, or a combination of these, or plasma obtained by an electrical method in which a magnetic field is applied to DC plasma, plasma obtained by a high output laser, or plasma obtained by a high output electron beam or ion beam. Whichever thermal plasma is used, it is preferable that the thermal plasma has a high temperature part of 10,000 K or higher, more preferably 10,000 K or higher and 25,000 K or lower, and in particular, that the plasma be one in which the particle generation time can be controlled.

[0076] A specific example of the configuration of the reaction step in the method for producing infrared absorbing particles of this embodiment using a plasma method will be described with reference to FIG.

[0077] The device shown in FIG. 1 is a hybrid plasma reactor 10 in which a DC plasma device and a high frequency plasma device are superimposed.

[0078] The hybrid plasma reactor 10 has a water-cooled quartz double tube 11 and a reaction vessel 12 connected to the water-cooled quartz double tube 11. A vacuum exhaust device 13 is connected to the reaction vessel 12.

[0079] A DC plasma torch 14 is provided above the water-cooled quartz double tube 11, and the DC plasma torch 14 is provided with a plasma generation gas supply port 15.

[0080] The system is configured so that sheath gas for generating high-frequency plasma and protecting the quartz tube can be supplied along the inner wall of the water-cooled quartz double tube 11 outside the plasma region, and a sheath gas inlet 16 is provided on the upper flange of the water-cooled quartz double tube 11.

[0081] A water-cooled copper coil 17 for generating high-frequency plasma is arranged around the water-cooled quartz double tube 11 .

[0082] A raw material powder carrier gas supply port 18 is provided near the DC plasma torch 14 and is connected by piping to a raw material powder supply device 19 that supplies raw material powder.

[0083] A gas supply device 20 can be connected by piping to the plasma generation gas supply port 15, the sheath gas inlet 16, and the raw material powder supply device 19, so that a predetermined gas can be supplied to each component from the gas supply device 20. If necessary, supply ports can be provided in addition to the components described above so that the components in the device can be cooled or a predetermined atmosphere can be created, and these can be connected to the gas supply device 20.

[0084] An example of the configuration of a method for producing composite tungsten oxide particles using the hybrid plasma reactor 10 will be described.

[0085] First, the reaction system consisting of the water-cooled quartz double tube 11 and the reaction vessel 12 is evacuated using the vacuum exhaust device 13. The degree of vacuum at this time is not particularly limited, but it can be evacuated to, for example, about 0.1 Pa (about 0.001 Torr). After the reaction system is evacuated, argon gas is supplied from the gas supply device 20, and the reaction system can be filled with argon gas. For example, it is preferable to have an argon gas flow system at 1 atmosphere within the reaction system.

[0086] Thereafter, a plasma gas can be supplied into the reaction vessel 12. The plasma gas is not particularly limited, but can be any gas selected from, for example, argon gas, a mixed gas of argon and helium (Ar-He mixed gas), a mixed gas of argon and nitrogen (Ar-N mixed gas), neon, helium, and xenon.

[0087] The supply flow rate of the plasma gas is not particularly limited, but for example, it can be introduced from the plasma generating gas supply port 15 at a flow rate of preferably 3 L / min to 30 L / min, more preferably 3 L / min to 15 L / min. Then, DC plasma can be generated.

[0088] Meanwhile, outside the plasma region, sheath gas for generating high-frequency plasma and protecting the quartz tube can be supplied in a spiral pattern from sheath gas inlet 16 along the inner wall of water-cooled quartz double tube 11. There are no particular limitations on the type or supply rate of the sheath gas, but for example, argon gas at 20 L / min to 50 L / min and hydrogen gas at 1 L / min to 5 L / min can be flowed to generate high-frequency plasma.

[0089] Then, a high frequency power supply can be applied to the water-cooled copper coil 17 for generating high frequency plasma. The conditions of the high frequency power supply are not particularly limited, but for example, a high frequency power supply of about 4 MHz and 15 kW to 50 kW can be applied.

[0090] After generating such a hybrid plasma, the raw material can be introduced using a carrier gas from a raw material powder carrier gas supply port 18 by a raw material powder supply device 19. There are no particular limitations on the carrier gas, and for example, a mixed gas consisting of argon gas at 1 L / min to 8 L / min and oxygen gas at 0.001 L / min to 0.8 L / min can be used.

[0091] The starting material mixture or composite tungsten oxide precursor is introduced into the plasma to carry out the reaction. The supply rate of the starting material from the raw material powder carrier gas supply port 18 is not particularly limited, but is preferably 1 g / min to 50 g / min, more preferably 1 g / min to 20 g / min.

[0092] By setting the feed rate of the starting material to 50 g / min or less, the proportion of the starting material passing through the center of the plasma flame can be sufficiently increased, the proportion of unreacted materials and intermediate products can be suppressed, and the proportion of the desired composite tungsten oxide particles produced can be increased. Also, by setting the feed rate of the starting material to 1 g / min or more, productivity can be increased.

[0093] The starting material supplied to the plasma is instantly vaporized in the plasma and undergoes a condensation process to produce composite tungsten oxide particles with an average primary particle size of 100 nm or less.

[0094] The particle size of the composite tungsten oxide particles obtained by the manufacturing method of this embodiment can be easily controlled by the plasma output, plasma flow rate, the amount of raw material powder supplied, and the like.

[0095] After the reaction, the composite tungsten oxide particles produced are deposited in the reaction vessel 12 and can be recovered.

[0096] The infrared absorbing particles obtained by the manufacturing method described above may be coated on the surface with a coating film. Since the coating film has already been described, a description thereof will be omitted here.

[0097] The method for producing infrared absorbing particles according to this embodiment has been described above. The infrared absorbing particles obtained by this production method can be evaluated and confirmed, for example, by the following method.

[0098] For example, the constituent elements of the infrared absorbing particles obtained by the above-described method for producing infrared absorbing particles can be quantitatively analyzed chemically. The analytical method is not particularly limited, but for example, the M element and tungsten can be analyzed by plasma emission spectroscopy, and oxygen can be analyzed by inert gas impulse heating fusion infrared absorption spectroscopy.

[0099] The crystal structure of the composite tungsten oxide contained in the infrared absorbing particles can be confirmed by powder X-ray diffraction.

[0100] The particle size of the infrared absorbing particles can be confirmed by particle size measurement based on TEM observation or dynamic light scattering. [Infrared curable ink composition] The infrared curable ink composition of this embodiment may contain infrared absorbing particles and a thermosetting resin. The thermosetting resin is preferably in an uncured state, specifically, in a state having fluidity, for example.

[0101] That is, for example, as shown in FIG. 3, the infrared curable ink composition 100 of this embodiment can contain the above-described infrared absorbing particles 110 and a thermosetting resin 120.

[0102] Note that FIG. 3 is a schematic diagram, and the infrared-curable ink composition 100 of this embodiment is not limited to this form. For example, while the infrared-absorbing particles 110 are depicted as spherical particles in FIG. 3, the shape of the infrared-absorbing particles 110 is not limited to this form and can have any shape. Furthermore, as described above, the infrared-absorbing particles 110 may have a coating on their surfaces. In addition to the infrared-absorbing particles 110 and the thermosetting resin 120, the electromagnetic-wave-absorbing particle dispersion 10 may also contain additives such as solvents and dispersants, as described below, as needed.

[0103] The components contained in the infrared curable ink composition of this embodiment will be described below. (1) Thermosetting resin The thermosetting resin is not particularly limited, but for example, one or more types selected from epoxy resin, urethane resin, acrylic resin, urea resin, melamine resin, phenol resin, ester resin, polyimide resin, silicone resin, unsaturated polyester resin, etc. can be used.

[0104] These thermosetting resins are cured by the application of thermal energy from the infrared-absorbing particles irradiated with infrared rays, and uncured resins can be used. 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. (2) Infrared absorbing particles The infrared absorbing particles may be the same as those described above. The infrared absorbing particles have already been described, so further description will be omitted here.

[0105] The content of the infrared absorbing particles in the infrared curable ink composition of this embodiment is not particularly limited, and can be selected depending on the properties required of the infrared curable ink composition.

[0106] The amount of infrared absorbing particles contained in the infrared curable ink composition of this embodiment may be selected and added in an amount that allows the uncured thermosetting resin to be cured during the curing reaction.

[0107] Therefore, the amount of infrared absorbing particles per coating area of ​​the near-infrared curable ink composition can be selected and determined taking into consideration the coating thickness when the infrared curable ink composition is applied.

[0108] The infrared absorbing particles are preferably dispersed in the infrared curable ink composition, for example, in a solvent as described below. The method for dispersing the infrared absorbing particles in the infrared curable ink composition is not particularly limited, but it is preferable to use a wet medium mill or the like. (3) Other ingredients The infrared curable ink composition of this embodiment can be composed only of the above-mentioned thermosetting resin and infrared absorbing particles, but can also contain any optional components, such as pigments, dyes, dispersants, solvents, etc., which will be described below depending on the purpose. Note that even when the infrared curable ink composition is composed only of a thermosetting resin and infrared absorbing particles as described above, this does not exclude the inclusion of unavoidable components, etc., that are mixed in during the manufacturing process. (3-1) Pigments and dyes As described above, the infrared curable ink composition of this embodiment may further contain one or more pigments selected from organic pigments, inorganic pigments, and dyes in order to color the ink composition. (3-1-1) Pigments The pigment is not particularly limited, and known pigments can be used without particular limitation. One or more pigments selected from organic pigments such as insoluble pigments and lake pigments, and inorganic pigments such as carbon black can be preferably used.

[0109] These pigments are preferably present in a dispersed state in the infrared curable ink composition of this embodiment. As a method for dispersing these pigments, any known method can be used without any particular limitation.

[0110] The insoluble pigment is not particularly limited, but examples thereof include azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine, thiazine, dioxazine, thiazole, phthalocyanine, and diketopyrrolopyrrole.

[0111] Although there are no particular limitations on the organic pigment, the following specific pigments can be preferably used.

[0112] Examples of pigments for magenta or red include CI Pigment Red 2, CI Pigment Red 3, CI Pigment Red 5, CI Pigment Red 6, CI Pigment Red 7, CI Pigment Red 15, CI Pigment Red 16, CI Pigment Red 48:1, CI Pigment Red 53:1, CI Pigment Red 57:1, CI Pigment Red 122, CI Pigment Red 123, CI Pigment Red 139, CI Pigment Red 144, CI Pigment Red 149, CI Pigment Red 166, CI Pigment Red 177, CI Pigment Red 178, CI Pigment Red 202, CI Pigment Red 222, and CI Pigment Violet 19.

[0113] Examples of orange or yellow pigments include CI Pigment Orange 31, CI Pigment Orange 43, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 15:3, CI Pigment Yellow 17, CI Pigment Yellow 74, CI Pigment Yellow 93, CI Pigment Yellow 128, CI Pigment Yellow 94, and CI Pigment Yellow 138.

[0114] Examples of pigments for green or cyan include CI Pigment Blue 15, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 16, CI Pigment Blue 60, and CI Pigment Green 7.

[0115] Examples of black pigments include CI Pigment Black 1, CI Pigment Black 6, and CI Pigment Black 7.

[0116] The inorganic pigment is not particularly limited either, but preferred examples include carbon black, titanium dioxide, zinc sulfide, zinc oxide, zinc phosphate, mixed metal oxide phosphate, iron oxide, manganese iron oxide, chromium oxide, ultramarine, nickel or chromium antimony titanium oxide, cobalt oxide, aluminum, aluminum oxide, silicon oxide, silicates, zirconium oxide, mixed oxides of cobalt and aluminum, molybdenum sulfide, rutile mixed phase pigments, rare earth sulfides, bismuth vanadate, and extender pigments made of aluminum hydroxide or barium sulfate.

[0117] The dispersed particle size (average dispersed particle size) of the dispersed pigment contained in the infrared-curable ink composition according to this embodiment is not particularly limited, but is preferably, for example, 1 nm or more and 200 nm or less. This is because if the dispersed particle size of the pigment dispersion is 1 nm or more and 200 nm or less, the storage stability of the infrared-curable ink composition is particularly good. The dispersed particle size can be measured, for example, using an ELS-8000 manufactured by Otsuka Electronics Co., Ltd., which is a particle size measuring device based on the dynamic light scattering method. (3-1-2) Dye There are no particular limitations on the dye, and either oil-soluble dyes or water-soluble dyes can be used, with yellow dyes, magenta dyes, cyan dyes, etc. being preferred.

[0118] Yellow dyes include, for example, aryl or heteryl azo dyes having phenols, naphthols, anilines, pyrazolones, pyridones, or open-chain active methylene compounds as coupling components; azomethine dyes having open-chain active methylene compounds as coupling components; methine dyes such as benzylidene dyes and monomethine oxonol dyes; and quinone dyes such as naphthoquinone dyes and anthraquinone dyes. Other dyes include quinophthalone dyes, nitro / nitroso dyes, acridine dyes, and acridinone dyes. These dyes may exhibit yellow only upon partial dissociation of the chromophore. In this case, the countercation may be an inorganic cation such as an alkali metal or ammonium, or an organic cation such as pyridinium or a quaternary ammonium salt, or may even be a polymer cation having these as a partial structure.

[0119] Examples of magenta dyes include aryl or heteryl azo dyes having phenols, naphthols, or anilines as coupling components; azomethine dyes having pyrazolones or pyrazolotriazoles as coupling components; methine dyes such as arylidene dyes, styryl dyes, merocyanine dyes, and oxonol dyes; carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes, and xanthene dyes; quinone dyes such as naphthoquinones, anthraquinones, and anthrapyridones; and condensed polycyclic dyes such as dioxazine dyes. These dyes may exhibit magenta only upon partial dissociation of the chromophore. In this case, the counter cation may be an inorganic cation such as an alkali metal or ammonium, or an organic cation such as a pyridinium or quaternary ammonium salt, or may even be a polymer cation having such a cation in its partial structure.

[0120] 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; aryl or heteryl azo dyes with phenols, naphthols, or anilines as coupling components; and indigo and thioindigo dyes. These dyes may exhibit cyan only upon partial dissociation of the chromophore. In this case, the countercation may be an inorganic cation such as an alkali metal or ammonium, or an organic cation such as a pyridinium or quaternary ammonium salt, or even a polymeric cation containing these cations. Black dyes such as polyazo dyes may also be used.

[0121] There are no particular limitations on the water-soluble dye, and direct dyes, acid dyes, food dyes, basic dyes, reactive dyes, etc. can be preferably used.

[0122] Specific dye names that can be preferably used as the water-soluble dye are listed below.

[0123] CI 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, CI Direct Violet 7, 9, 47, 48, 51, 66, 90, 93, 94, 95, 98, 100, 101, CI 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, CI 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, CI 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, CI 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 CI Acid Violet 5, 34, 43, 47, 48, 90, 103, 126, CI 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, CI 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, CI Acid Black 7, 24, 29, 48, 52:1, 172, CI Reactive Red 3, 13, 17, 19, 21, 22, 23, 24, 29, 35, 37, 40, 41, 43, 45, 49, 55, CI Reactive Violet 1, 3, 4, 5, 6, 7, 8, 9, 16, 17, 22, 23, 24, 26, 27, 33, 34, CI Reactive Yellow 2, 3, 13, 14, 15, 17, 18, 23, 24, 25, 26, 27, 29, 35, 37, 41, 42, CI Reactive Blue 2, 3, 5, 8, 10, 13, 14, 15, 17, 18, 19, 21, 25, 26, 27, 28, 29, 38, CI Reactive Black 4, 5, 8, 14, 21, 23, 26, 31, 32, 34, CI Basic Red 12, 13, 14, 15, 18, 22, 23, 24, 25, 27, 29, 35, 36, 38, 39, 45, 46, CI Basic Violet 1, 2, 3, 7, 10, 15, 16, 20, 21, 25, 27, 28, 35, 37, 39, 40, 48, CI Basic Yellow 1, 2, 4, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 39, 40, CI Basic Blue 1, 3, 5, 7, 9, 22, 26, 41, 45, 46, 47, 54, 57, 60, 62, 65, 66, 69, 71, CI Basic Black 8, etc.

[0124] The particle size of the pigment or other coloring material described above is preferably determined in consideration of the characteristics of the coating device for the infrared curable ink composition.

[0125] (3-2) Dispersant The infrared curable ink composition of this embodiment may further contain a dispersant. That is, the infrared absorbing particles described above may be dispersed together with a dispersant in a thermosetting resin or a solvent, which is an optional component described below. The addition of a dispersant makes it possible to easily disperse the infrared absorbing particles in the infrared curable ink composition. Furthermore, when a coating film of the infrared curable ink composition is cured, variation in curing can be particularly suppressed.

[0126] 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 preferably has a main chain of a polyester, polyacrylic, polyurethane, polyamine, polycaprolactone, polystyrene, or the like, and functional groups such as an amino group, epoxy group, carboxyl group, hydroxyl group, or sulfo group. This is because dispersants with such a molecular structure do not deteriorate when a coating film of the infrared curable ink composition of this embodiment is intermittently irradiated with infrared rays for several tens of seconds. This is because the occurrence of defects such as coloration due to such deterioration can be particularly suppressed.

[0127] Specific examples of commercially available dispersants that can be suitably used include SOLSPERSE3000, SOLSPERSE9000, SOLSPERSE11200, SOLSPERSE13000, SOLSPERSE13240, SOLSPERSE13650, SOLSPERSE13940, SOLSPERSE16000, SOLSPERSE17000, SOLSPERSE18000, SOLSPERSE20000, SOLSPERSE21000, SOLSPERSE24000SC, SOLSPERSE24000GR, SOLSPERSE26000, SOLSPERSE27000, SOLSPERSE28000, SOLSPERSE31845, SOLSPERSE32000, SOLSPERSE32500, SOLSPERSE32550, SOLSPERSE32600, SOLSPERSE33000, SOLSPERSE33500, SOLSPERSE34750, SOLSPERSE35100, SOLSPERSE35200, SOLSPERSE36600, SOLSPERSE37500, SOLSPERSE38500, SOLSPERSE39000, SOLSPERSE41000, SOLSPERSE41090, SOLSPERSE53095, SOLSPERSE55000, SOLSPERSE56000, SOLSPERSE76500, etc.; Disperbyk-101, Disperbyk-103, Disperbyk-107, Disperbyk-108, Disperbyk-109, Disperbyk-110, Disperbyk-111, Disperbyk-112, Disperbyk-116, Disperbyk-130, Disperbyk-140, Disperbyk-142, Disperbyk-145, Disperbyk-154, Disperbyk-161, Disperbyk-162, Disperbyk-163, Disperbyk-164, Disperbyk-165, Disperbyk-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, Disperbyk-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, BYK-P104, BYK-P104S, BYK-220S, BYK-6919, etc. manufactured by BIG CHEMICAL JAPAN CO., LTD; BASF Japan Ltd. EFKA4008, EFKA4046, EFKA4047, EFKA4015, EFKA4020, EFKA4050, EFKA4055, EFKA4060, EFKA4080, EFKA4300, EFKA4330, EFKA4400, EFKA4401, 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., Ltd.

[0128] (3-3) Solvent The infrared curable ink composition of this embodiment may contain a solvent together with the thermosetting resin. That is, the infrared curable ink composition of this embodiment may further contain a solvent. When the infrared curable ink composition contains a solvent, the infrared absorbing particles and the like are contained and dispersed in the solvent, and therefore the solvent can also be called a dispersion medium.

[0129] Examples of solvents that can be used in the infrared-curable ink composition 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, ketones such as acetone, methyl ethyl ketone, diethyl ketone, cyclohexanone, isobutyl ketone, and methyl isobutyl ketone, and various organic solvents such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, polyethylene glycol, and polypropylene glycol.

[0130] It is also preferable to use a monomer of an uncured thermosetting resin together with or instead of the solvent of the infrared curable ink composition, in which case a configuration can be adopted in which no solvent such as an organic solvent is used.

[0131] Furthermore, it is also preferable to use, as the solvent for the infrared-curable ink composition, a reactive organic solvent having a functional group such as 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. (4) Infrared-curable ink composition The infrared curable ink composition of this embodiment can be prepared, for example, by adding infrared absorbing particles to an uncured thermosetting resin. Alternatively, the infrared curable ink composition of this embodiment may be prepared by dispersing the infrared absorbing particles in an appropriate solvent and then adding the uncured thermosetting resin.

[0132] The infrared curable ink composition of this embodiment may contain composite tungsten oxide particles as infrared absorbing particles. The infrared curable ink composition of this embodiment may be, for example, an infrared curable ink composition containing infrared absorbing particles, a solvent, a dispersant, and a thermosetting resin. The solvent may be removed from the infrared curable ink composition during use. Alternatively, the infrared curable ink composition of this embodiment may contain composite tungsten oxide particles as infrared absorbing particles, a dispersant, and a thermosetting resin without using a solvent.

[0133]

[0042] The infrared-curable ink composition of this embodiment contains the infrared-absorbing particles described above, and therefore can achieve a more neutral color tone when, for example, it is applied to a substrate and irradiated with infrared rays to form a cured product (cured body). Furthermore, because the infrared-absorbing particles have excellent near-infrared absorption properties, they can supply sufficient heat when irradiated with near-infrared rays, etc., and can sufficiently enhance the adhesion of the resulting cured body to the substrate.

[0134] The infrared-curable ink composition of this embodiment can be used in the same applications as conventional inks that form infrared-cured films on a substrate. The infrared-curable ink composition of this embodiment can also be used in stereolithography, in which a predetermined amount of the ink composition is applied to a substrate, and then irradiated with infrared light to cure and build up the composition, thereby forming a three-dimensional object.

[0135] By including a solvent in the infrared curable ink composition of this embodiment, the viscosity of the ink composition can be adjusted, which improves the ease of handling when the ink composition is applied to a substrate or the like.

[0136] However, as described above, the infrared curable ink composition of this embodiment does not need to contain a solvent. When the infrared curable ink composition of this embodiment does not contain a solvent, it can contain, for example, infrared absorbing particles, a thermosetting resin, and, as necessary, a dispersant, etc. When the infrared curable ink composition of this embodiment does not contain a solvent, it is possible to omit the operation of volatilizing the solvent, etc., and therefore it is possible to improve the efficiency when curing an applied object of the infrared curable ink composition.

[0137] 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 in which a reduced pressure operation is applied can be used. [Infrared cured product] The infrared-cured product of this embodiment can be a cured product of the infrared-curable ink composition described above.

[0138] The infrared-cured product of the present embodiment may be disposed on a substrate, or may exist alone without including a substrate, etc. The substrate will be described below in the method for producing an infrared-cured product.

[0139] The infrared-cured product of the present embodiment may have a film shape or a three-dimensional shape, etc. When it has a film shape, the infrared-cured product of the present embodiment can also be called an infrared-cured film. [Method of manufacturing infrared cured product] The infrared-cured product of this embodiment can be produced, for example, by a method for producing an infrared-cured product including a coating step and a curing step, which will be described below. The method for producing an infrared-cured product of this embodiment can produce the infrared-cured product described above.

[0140] In the coating step, the infrared curable ink composition described above can be applied to form a coated object. After the coating step, the solvent and the like can be removed as necessary.

[0141] In the curing step, the applied material can be cured by irradiating it with infrared rays.

[0142] The application step and the curing step can be repeated to obtain an infrared-cured product of a desired shape and size. The infrared-cured product can also have a film shape, in which case the infrared-cured product can be called an infrared-cured film, and the method for producing the infrared-cured product can also be called a method for producing an infrared-cured film.

[0143] Furthermore, according to the method for producing an infrared-cured product of this embodiment, it is also possible to produce an infrared-cured product that is a three-dimensional object on a substrate, for example.

[0144] According to the method for producing an infrared-cured product of this embodiment, an infrared-cured product can be obtained by irradiating a coated product obtained by applying the infrared-curable ink composition to a substrate with infrared rays, for example. This is because the infrared-absorbing particles in the infrared-curable ink composition absorb the irradiated infrared rays and generate heat, and the generated heat energy promotes reactions such as polymerization reactions, condensation reactions, and addition reactions of monomers, oligomers, and the like contained in the uncured thermosetting resin, causing a curing reaction of the thermosetting resin.

[0145] When the infrared curable ink composition contains a solvent, the solvent can also be volatilized by the heat generated by the infrared absorbing particles due to the irradiation of infrared rays in the curing step.

[0146] Even if the infrared-cured film of this embodiment is further irradiated with infrared rays, the cured film will not re-melt. This is because the infrared-cured film of this embodiment contains a thermosetting resin that is formed by curing the uncured thermosetting resin in the infrared-curable ink composition, and therefore will not re-melt even if the infrared-absorbing particles generate heat upon irradiation with infrared rays.

[0147] This property is particularly effective when the infrared-curable ink composition of this embodiment is applied to a stereolithography method in which a three-dimensional object is formed by curing the ink composition, building up the ink, and repeatedly applying the ink composition and irradiating it with infrared rays.

[0148] Each step will be described below. (1) Coating process In the coating step, for example, the infrared curable ink composition described above can be coated onto a substrate to form a coating film.

[0149] In the coating step, the material of the substrate (base material) onto which the infrared curable ink composition is coated is not particularly limited.

[0150] The substrate may be one or more types of substrate selected from, for example, paper, resin, glass, and the like.

[0151] The resin is not particularly limited, but may be one or more selected from polyesters such as PET (polyethylene terephthalate), acrylic, urethane, polycarbonate, polyethylene, ethylene-vinyl acetate copolymer, vinyl chloride, fluororesin, polyimide, polyacetal, polypropylene, nylon, etc.

[0152] The shape of the substrate is not particularly limited, and can be any shape required for the infrared-cured product, for example, a plate shape.

[0153] The method for applying the infrared-curable ink composition to the substrate surface is not particularly limited, and methods such as dipping, flow coating, spraying, bar coating, spin coating, gravure coating, roll coating, screen printing, and blade coating can be used. (2) Curing process In the curing step, the applied material is irradiated with infrared rays to cure the infrared-curable ink composition. By carrying out the curing step, an infrared-cured product can be produced.

[0154] The infrared-curable ink composition is preferably cured by infrared irradiation, more preferably by near-infrared irradiation, because infrared radiation has a high energy density and can efficiently impart the energy required to cure the resin in the infrared-curable ink composition.

[0155] It is also preferable to cure the 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.

[0156] In this specification, infrared radiation refers to electromagnetic waves having a wavelength in the range of 0.75 μm to 1 mm, near-infrared radiation refers to infrared radiation with a wavelength of 0.75 μm to 4 μm, and far-infrared radiation refers to infrared radiation with a wavelength of longer than 4 μm and shorter than 1000 μm. Generally, irradiation with either far-infrared radiation or near-infrared radiation can cure an infrared-curable ink composition and produce similar effects. However, irradiation with near-infrared radiation can cure a coating film more efficiently in a shorter time.

[0157] As described above, when curing the infrared-curable ink composition, electromagnetic waves can be irradiated together with infrared rays. Microwaves are preferably used as such electromagnetic waves. Microwaves refer to electromagnetic waves having a wavelength in the range of 1 mm to 1 m.

[0158] The microwaves to be irradiated preferably have a power of 200 W or more and 1000 W or less. A power of 200 W or more promotes evaporation of solvents and the like remaining in the infrared-curable ink composition, while a power of 1000 W or less ensures mild irradiation conditions and there is no risk of deterioration of the substrate or thermosetting resin.

[0159] The infrared irradiation time for the infrared-curable ink composition varies depending on the irradiation energy and wavelength, the composition of the infrared-curable ink composition, and the amount of the infrared-curable ink composition applied, and is not particularly limited. For example, the infrared irradiation time is generally preferably 0.1 seconds or longer. By setting the irradiation time to 0.1 seconds or longer, it is possible to irradiate the infrared ray sufficiently to cure the infrared-curable ink composition. By extending the irradiation time, it is possible, for example, to sufficiently dry the solvent in the infrared-absorbing curable ink composition. However, with high-speed printing and application in mind, the irradiation time is preferably 30 seconds or shorter, and more preferably 10 seconds or shorter.

[0160] The infrared radiation source is not particularly limited, and infrared radiation may be obtained directly from a heat source, or effective infrared radiation may be obtained through the intermediation of a heat medium. For example, infrared radiation can be obtained by heating a discharge lamp of mercury, xenon, cesium, sodium, etc., a carbon dioxide gas laser, or an electric resistor of platinum, tungsten, nichrome, kanthal, etc. Preferred radiation sources include halogen lamps and laser light. Halogen lamps have advantages such as good thermal efficiency and quick start-up.

[0161] The infrared radiation to the coated object may be applied from the side of the substrate on which the infrared-curable ink composition is applied, or from the backside. Simultaneous irradiation from both sides is also preferred, and it is also preferred to combine irradiation with elevated temperature drying or air drying. It is also more preferred to use a light-collecting plate as necessary. By combining these methods, it is possible to cure the infrared-curable ink composition with infrared radiation for a short period of time.

[0162] According to the method for producing an infrared-cured product of this embodiment, for example, an infrared-cured film, which is a film-like infrared-cured product, can be produced. Furthermore, by repeatedly laminating cured products of the infrared-curable ink composition, a three-dimensional object can also be formed. That is, by repeatedly performing the above-described coating step and irradiation step, an infrared-cured product having a desired three-dimensional structure can also be produced.

[0163] According to the method for producing an infrared-cured product of this embodiment, a stereolithography method can be implemented. That is, the method can be a stereolithography method including the coating step and the curing step described above.

[0164] The infrared-absorbing particles contained in the infrared-curable ink composition used to produce the infrared-cured product of this embodiment are transparent to visible light, and therefore a transparent infrared-shielding film can be easily obtained by curing the composition with infrared rays.

[0165] As described above, the infrared-curable ink composition can also contain at least one pigment or dye. A colored film can be easily obtained by using an infrared-curable ink composition containing such a pigment. Because the color of the colored film is hardly affected by the infrared-absorbing particles, the composition can be used for color filters of liquid crystal displays, etc.

[0166] Pigments and the like that can be suitably used to obtain the colored film have already been explained in the section on the infrared curable ink composition, and therefore will not be explained here. [Example]

[0167] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. (Evaluation method) The evaluation methods used in each of the examples and comparative examples will be described below. (1) Composition analysis (Cs, W, O quantitative analysis) Composition analysis was carried out on the composite tungsten oxide (cesium tungsten oxide, etc.) particles, which are infrared absorbing particles, produced in the following Examples and Comparative Examples.

[0168] Cs was evaluated using a flame atomic absorption spectrometer (VARIAN, model: SpectrAA 220FS). W was evaluated using an ICP optical emission spectrometer (Shimadzu, model: ICPE9000). O was evaluated using an oxygen / nitrogen simultaneous analyzer (LECO, model: ON836). K and Rb were also evaluated in the same manner as Cs.

[0169] The evaluation results are shown in the "Chemical Formula" column of "Composite Tungsten Oxide" in Table 1. (2) Crystal structure and crystallite size In measuring the crystalline structure of the composite tungsten oxide particles, which are infrared absorbing particles, first, the X-ray diffraction patterns of the infrared absorbing particles produced in the following Examples and Comparative Examples were measured by powder X-ray diffraction (θ-2θ method) using a powder X-ray diffractometer (X'Pert-PRO / MPD manufactured by PANalytical, Spectris Inc.). The crystalline structure of the composite tungsten oxide contained in the infrared absorbing particles was identified from the obtained X-ray diffraction patterns.

[0170] In addition, the X-ray diffraction pattern of the composite tungsten oxide particles obtained by removing the solvent from the infrared absorbing particle dispersion liquid prepared in the following Examples and Comparative Examples was measured by the powder X-ray diffraction method using the above-mentioned powder X-ray diffractometer.Then, the crystallite size of the composite tungsten oxide was calculated from the obtained X-ray diffraction pattern using the Rietveld method. (3) Peeling test of infrared cured film, evaluation of long-term storage stability One hundred square-shaped cuts were made in the infrared-cured films obtained in the following Examples and Comparative Examples using a cutter guide with a gap of 1 mm, and 18 mm wide tape (Cellotape (registered trademark) CT-18 manufactured by Nichiban Co., Ltd.) was applied to the square-shaped cut surfaces, and a 2.0 kg roller was rolled back and forth 20 times to completely adhere the tape. After that, the tape was rapidly peeled off at a peeling angle of 180 degrees, and the number of peeled squares was counted. The number of peeled squares was used to evaluate the film as follows. 〇: 0 peeled squares △: 1 to 3 peeled squares ×: 4 or more peeled squares A rating of ◯ means that infrared irradiation generates sufficient heat to cure the thermosetting resin and result in an infrared-cured film with excellent adhesion to the substrate. Δ and × indicate that adhesion to the substrate is poorer than when the rating is ◯, in that order.

[0171] An infrared-curable ink composition and an infrared-cured film were prepared under the same conditions, except that the infrared-absorbing particle dispersion liquid containing the infrared-absorbing particles was stored at room temperature for 3 months, and a peel test was similarly performed. The results of the peel test were used to evaluate the long-term storage stability. (Experimental example) The manufacturing conditions of the samples in the examples and comparative examples will be explained below. [Example 1] (Preparation of infrared absorbing particles) 23.5 g of Cs2CO3 was dissolved in 36 g of water, and this was added to 109 g of H2WO4 and thoroughly stirred, and then dried to obtain a raw material mixture according to Example 1 (raw material preparation step).

[0172] Next, the reaction step was carried out using the raw material mixture prepared in the raw material preparation step, using the hybrid plasma reactor 10 shown in FIG. 1 in which DC plasma and high frequency plasma are superimposed.

[0173] First, the reaction system was evacuated to about 0.1 Pa (about 0.001 torr) using the vacuum exhaust device 13, and then completely replaced with argon gas to create an argon flow system at 1 atmosphere.

[0174] DC plasma was generated by flowing argon gas at 8 L / min through the plasma generating gas supply port 15. The DC power input at this time was 6 kW.

[0175] Furthermore, argon gas at 40 L / min and hydrogen gas at 3 L / min were flowed in a spiral (or swirling) pattern from the sheath gas inlet 16 along the inner wall of the water-cooled quartz double tube 11 as gases for generating high-frequency plasma and protecting the quartz tube, thereby generating high-frequency plasma.

[0176] The input of the high frequency power supply was set to 45 kW. After generating such a hybrid plasma, the raw material mixture according to Example 1 was supplied into the plasma from the raw material powder supply device 19 at a supply rate of 2 g / min using a mixed gas of argon gas at 3 L / min and oxygen gas at 0.01 L / min as a carrier gas.

[0177] As a result, the raw material was instantly vaporized and condensed in the plasma tail flame to form fine particles. Cesium tungsten oxide particles a, which are infrared absorbing particles, were collected at the bottom of the reaction vessel 12.

[0178] The particle diameter of the recovered cesium tungsten oxide particles a was determined by TEM observation, and it was confirmed that the particle diameter of the 30 particles evaluated was 10 nm or more and 50 nm or less. The particle diameter was calculated by taking the diameter of the smallest circle circumscribing the particle to be evaluated as the particle diameter of the particle. In the other examples and comparative examples below, the particle diameter of the infrared absorbing particles was evaluated under the same conditions and by the same method.

[0179] The quantitative analysis of Cs, W, and O of the recovered cesium tungsten oxide particles a revealed that they were 14.7 wt%, 65.5 wt%, and 18.3 wt%, respectively. The chemical formula calculated from the quantitative analysis was Cs, as shown in Table 1. 0.31 WO 3.21 We were able to confirm that this is the case.

[0180] When the crystal structure of the compound contained in cesium tungsten oxide particle a was identified, it was found to be a hexagonal Cs0.3 The same peaks as those of WO3 were confirmed. As described above, the crystal structure of the obtained composite tungsten oxide can be identified by the X-ray diffraction pattern. In the case of this example, as described above, the crystal structure of the compound contained in the composite tungsten oxide particles matches the peaks of a similar hexagonal composite tungsten oxide. Therefore, it can be confirmed that the crystal structure of the composite tungsten oxide obtained in this example, i.e., cesium tungsten oxide, is hexagonal. (Preparation of Infrared-Absorbing Particle Dispersion (A-1)) Next, 20% by mass of cesium tungsten oxide particles a and 80% by mass of pure water were weighed, loaded into a paint shaker (manufactured by Asada Iron Works Co., Ltd.) containing 0.3 mm diameter ZrO2 beads, and ground and dispersed for 50 minutes to prepare an infrared-absorbing particle dispersion liquid (Liquid A-1).

[0181] Here, the dispersed particle diameter of the cesium tungsten oxide particles (a-1) in the A-1 solution was measured using a particle size measuring device (ELS-8000 manufactured by Otsuka Electronics Co., Ltd.) based on the dynamic light scattering method, and was found to be 80 nm.

[0182] Furthermore, the crystallite diameter of the cesium tungsten oxide particles (a-1) after separating the A-1 solution and removing the solvent was 24 nm. When the infrared curable ink composition was prepared, the particle diameter, dispersed particle diameter, and crystallite diameter of the infrared absorbing particles were evaluated in the same manner as in the case of the dispersion liquid described above, and it was confirmed that the same values ​​were shown. Similarly, in the following examples and comparative examples, the particle diameter, dispersed particle diameter, and crystallite diameter of the infrared absorbing particles in the infrared curable ink composition were the same as the evaluation results of the infrared absorbing particles after production and the dispersion liquid. (Preparation of infrared curable ink composition) Liquid A-1 was heated to 70°C and kept at this temperature for 500 hours while stirring. The solvent was then removed from Liquid A-1, and the mixture was dried under a nitrogen atmosphere. 20% by mass of the resulting dry powder, 65% by mass of methyl isobutyl ketone, and 15% by mass of an acrylic dispersant were weighed, loaded into a paint shaker (manufactured by Asada Iron Works Co., Ltd.) containing 0.3 mm diameter ZrO2 beads, and crushed for 50 minutes to prepare infrared-absorbing particle dispersion (A-2).

[0183] The infrared-curable ink composition of Example 1 was prepared by mixing 25% by mass of this A-2 liquid with 75% by mass of a commercially available one-component uncured epoxy resin-based heat-curable ink (MEG Screen Ink (Medium (Clear)) manufactured by Teikoku Ink Mfg. Co., Ltd.).

[0184] This infrared-curable ink composition was applied to a glass plate using a bar coater (No. 10) to form a coating (coating film) (coating step). A line heater HYP-14N (output: 980 W) manufactured by Hibeck Co., Ltd. was installed as an infrared radiation source at a height of 5 cm from the coating surface, and infrared radiation was irradiated onto the coating for 10 seconds to form an infrared-cured film (curing step). (Initial peeling test) The obtained cured film was confirmed to be transparent by visual inspection. The above-mentioned peeling test of the infrared cured film was carried out, and the evaluation result was good. The evaluation results are shown in the "Initial evaluation" column of Table 1. (Evaluation of long-term storage stability) Furthermore, the A-2 liquid was stored at room temperature for 3 months, and an infrared-curable ink composition was prepared in the same manner as above, except that the A-2 liquid after storage was used, and an infrared-cured film was produced.

[0185] Specifically, 25% by mass of A-2 liquid after 3 months of storage was mixed with 75% by mass of a commercially available, uncured, one-component epoxy resin-based heat-curable ink (TEIKOKU INK Mfg. Co., Ltd., MEG Screen Ink (Medium (Clear))) to prepare a heat-curable ink composition after 3 months of storage. An infrared-cured film was prepared in the same manner as above, except that the infrared-curable ink composition was used, and a peel test was performed on the infrared-cured film. The evaluation results are shown in the "Evaluation after storage" column of Table 1. [Example 2] Infrared absorbing particles were prepared using a high frequency plasma reactor 30 shown in FIG.

[0186] The high frequency plasma reactor 30 has a water-cooled quartz double tube 31 and a reaction vessel 32 connected to the water-cooled quartz double tube 31. A vacuum exhaust device 33 is connected to the reaction vessel 32.

[0187] Above the water-cooled quartz double tube 31, a plasma generating gas supply port 34 is provided.

[0188] The water-cooled quartz double tube 31 is configured so that sheath gas for generating high-frequency plasma and for protecting the quartz tube can be supplied along the inner wall thereof, and a sheath gas inlet 36 is provided on the upper flange of the water-cooled quartz double tube 31.

[0189] A water-cooled copper coil 37 for generating high-frequency plasma is arranged around the water-cooled quartz double tube 31 .

[0190] A raw material powder carrier gas supply port 38 is provided near the plasma generating gas supply port 34 and is connected by a pipe to a raw material powder supply device 39 that supplies raw material powder.

[0191] The plasma generating gas supply port 34, sheath gas inlet 36, and raw material powder supply device 39 can be connected to a gas supply device 40 by piping, so that a predetermined gas can be supplied to each component from the gas supply device 40. Note that, if necessary, supply ports other than those for the components mentioned above can be provided and connected to the gas supply device 40 so that the components in the device can be cooled or a predetermined atmosphere can be created.

[0192] In this example, high-frequency plasma was generated by first flowing argon gas at 30 L / min through the plasma generating gas supply port 34, and then supplying a mixture of argon gas at 40 L / min and hydrogen gas at 3 L / min in a spiral fashion through the sheath gas inlet 36. The high-frequency power input at this time was 45 kW.

[0193] Next, the raw material mixture prepared in Example 1 was supplied into the plasma at a rate of 2 g / min from raw material powder supply device 39 using a mixed gas of argon gas at 3 L / min and oxygen gas at 0.01 L / min as a carrier gas.

[0194] As a result, the particle diameter of the infrared absorbing material particles recovered at the bottom of the reaction vessel 32 was found to be 10 nm or more and 50 nm or less by TEM observation.

[0195] The X-ray diffraction pattern of the obtained cesium tungsten oxide particles, which are infrared absorbing particles according to Example 2, was measured by powder X-ray diffraction (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Cs 0.3 The same peak as that of WO3 was confirmed.

[0196] An infrared curable ink composition and an infrared cured film were prepared and evaluated in the same manner as in Example 1, except that the infrared absorbing particles of Example 2 were used. The evaluation results are shown in Table 1.

[0197] Furthermore, in the same manner as in Example 1, the solvent was removed from the infrared absorbing particle dispersion, and the cesium tungsten oxide particles, which were infrared absorbing particles, recovered from the dispersion were evaluated for their crystallite diameter, which was 25.2 nm, and the lattice constants were a-axis 7.4146 Å and c-axis 7.5995 Å. [Example 3] Infrared absorbing particles according to Example 3 were produced and evaluated in the same manner as in Example 2, except that in Example 2, a mixed gas of argon gas at 5 L / min and oxygen gas at 0.01 L / min was used as the carrier gas when supplying the raw material mixture.

[0198] The particle diameter of the infrared absorbing particles recovered from the high frequency plasma reactor 30 was found to be 10 nm or more and 50 nm or less by TEM observation.

[0199] The X-ray diffraction pattern of the obtained infrared absorbing particles according to Example 3 was measured by powder X-ray diffraction method (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Cs 0.3 The same peak as that of WO3 was confirmed.

[0200] An infrared curable ink composition and an infrared cured film were prepared and evaluated in the same manner as in Example 1, except that the infrared absorbing particles of Example 3 were used. The evaluation results are shown in Table 1.

[0201] The infrared absorbing particles, ie, composite tungsten oxide particles, recovered from the dispersion by removing the solvent in the same manner as in Example 1 had a crystallite diameter of 24.5 nm. The lattice constants determined by the Rietveld method were an a-axis of 7.4148 Å and a c-axis of 7.5995 Å. [Example 4] Infrared absorbing particles according to Example 4 were produced in the same manner as in Example 2, except that in Example 2, a mixed gas of argon gas at 4 L / min and oxygen gas at 0.01 L / min was used as the carrier gas when supplying the raw material mixture.

[0202] The particle diameter of the infrared absorbing particles recovered from the high frequency plasma reactor 30 was found to be 10 nm or more and 50 nm or less by TEM observation.

[0203] The X-ray diffraction pattern of the obtained infrared absorbing particles according to Example 4 was measured by powder X-ray diffraction method (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Cs 0.3 The same peak as that of WO3 was confirmed.

[0204] An infrared curable ink composition and an infrared cured film were prepared and evaluated in the same manner as in Example 1, except that the infrared absorbing particles of Example 4 were used. The evaluation results are shown in Table 1.

[0205] The infrared absorbing particles, ie, composite tungsten oxide particles, recovered from the dispersion by removing the solvent in the same manner as in Example 1 had a crystallite diameter of 21.7 nm. The lattice constants determined by the Rietveld method were an a-axis of 7.4116 Å and a c-axis of 7.5955 Å. [Example 5] 13.43 g of K2CO3 was dissolved in 59 g of water, and this was added to 180 g of H2WO4 and thoroughly stirred, and then dried to obtain a raw material mixture according to Example 5.

[0206] The raw material mixture according to Example 5 was supplied into the plasma in the same manner as in Example 2, and the infrared absorbing particles according to Example 5, K 0.27 WO 3.14 A powder of particles was obtained.

[0207] The particle diameter of the recovered infrared absorbing particles was found to be between 10 nm and 50 nm by TEM observation.

[0208] The X-ray diffraction pattern of the obtained infrared absorbing particles according to Example 5 was measured by powder X-ray diffraction method (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal K 0.27 The same peak as that of WO3 was confirmed.

[0209] An infrared curable ink composition and an infrared cured film were prepared and evaluated in the same manner as in Example 1, except that the infrared absorbing particles of Example 5 were used. The evaluation results are shown in Table 1.

[0210] Furthermore, similarly to Example 1, the solvent was removed from the infrared absorbing particle dispersion, and the composite tungsten oxide particles, which were infrared absorbing particles, recovered from the dispersion had a crystallite diameter of 24.4 nm. [Example 6] 22.17 g of Rb2CO3 was dissolved in 50 g of water, and this was added to 150 g of H2WO4. After sufficient stirring, the mixture was dried to obtain a raw material mixture according to Example 6.

[0211] The raw material mixture according to Example 6 was supplied into plasma in the same manner as in Example 2 to form the near-infrared absorbing particles according to Example 6, Rb 0.3 WO 3.16 A powder of particles was obtained.

[0212] The particle diameter of the recovered infrared absorbing particles was found to be between 10 nm and 50 nm by TEM observation.

[0213] The X-ray diffraction pattern of the obtained infrared absorbing particles according to Example 6 was measured by powder X-ray diffraction method (θ-2θ method). The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Rb 0.3 The same peak as that of WO3 was confirmed.

[0214] An infrared curable ink composition and an infrared cured film were prepared and evaluated in the same manner as in Example 1, except that the infrared absorbing particles of Example 6 were used.

[0215] Furthermore, similarly to Example 1, the solvent was removed from the infrared absorbing particle dispersion, and the composite tungsten oxide particles, which were infrared absorbing particles, recovered from the dispersion had a crystallite diameter of 23.9 nm and lattice constants of an a-axis of 7.3958 Å and a c-axis of 7.5605 Å. [Comparative Example 1] The cesium tungsten oxide particles a obtained in Example 1 were fired at 500° C. for 1 hour in a 3% H 2 gas atmosphere with N 2 gas as a carrier gas to prepare infrared absorbing particles according to Comparative Example 1.

[0216] The infrared absorbing particles according to Comparative Example 1 were coarser than the infrared absorbing particles according to Example 1 due to the effect of being fired at 500°C for 1 hour under a 3% H2 gas atmosphere, and therefore the dispersion and grinding time for preparing the infrared absorbing particle dispersion was set to 2 hours.

[0217] An infrared-curable ink composition and an infrared-cured film were prepared and evaluated in the same manner as in Example 1, except that the above infrared-absorbing particle dispersion liquid was used instead of Liquid A-1 in Example 1. The evaluation results are shown in Table 1.

[0218] The X-ray diffraction pattern of the obtained infrared absorbing particles according to Comparative Example 1 was measured by powder X-ray diffraction (θ-2θ method) in the same manner as in Example 1. The crystal structure contained in the particles was identified from the obtained X-ray diffraction pattern, and it was found to be hexagonal Cs 0.3 The same peak as that of WO3 was confirmed.

[0219] Furthermore, similarly to Example 1, the solvent was removed from the infrared absorbing particle dispersion liquid, and the recovered infrared absorbing particles, namely, composite tungsten oxide particles, had a crystallite diameter of 9 nm and lattice constants of an a-axis of 7.4100 Å and a c-axis of 7.6300 Å.

[0220] [Table 1] [summary] As is clear from the evaluation results, an infrared-cured film could be formed by irradiating infrared rays for a short period of time, 10 seconds, using the infrared-curable ink compositions according to Examples 1 to 6, confirming that the infrared-curable ink compositions have excellent infrared absorption properties.

[0221] Furthermore, it was confirmed that the results of the peel test did not change even when an infrared-cured film was produced using an infrared-curable ink composition prepared after storing the raw infrared-absorbing particle dispersion liquid for three months in Examples 1 to 6. In contrast, it was confirmed that the results of the peel test deteriorated in Comparative Example 1 when an infrared-cured film was produced using an infrared-curable ink composition prepared after storing the raw infrared-absorbing particle dispersion liquid for three months.

[0222] That is, the infrared-curable ink compositions of Examples 1 to 6 did not show any significant change in infrared absorption properties even after three months of storage, and it was confirmed that irradiation with infrared rays generated sufficient heat to cure the thermosetting resin and produce an infrared-cured film with excellent adhesion to the substrate. In contrast, the infrared-curable ink composition of Comparative Example 1 showed a decrease in infrared absorption properties after three months of storage, which is thought to be why the resulting infrared-cured film had decreased adhesion to the substrate.

[0223] From the above results, it was confirmed that the infrared curable ink compositions of Examples 1 to 6 are superior to the infrared curable ink composition of Comparative Example 1 in long-term storage stability.

[0224] In the above examples and comparative examples, the infrared-absorbing particle dispersion was stored for three months, and then an infrared-curable ink composition was prepared and evaluated. It was confirmed that the same tendency was observed even when the infrared-curable ink composition was stored for a long period of time after preparation.

[0225] This application claims priority based on Patent Application No. 2021-138766, filed with the Japan Patent Office on August 27, 2021, and the entire contents of Patent Application No. 2021-138766 are incorporated by reference into this international application. [Explanation of symbols]

[0226] 100 Infrared curable ink composition 110 Infrared absorbing particles 120 Thermosetting resin

Claims

1. The ink contains infrared absorbing particles and a thermosetting resin, The infrared absorbing particles are represented by the general formula M ｘ W ｙ O ｚ (M element is one or more elements selected from H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I; W is tungsten; O is oxygen; and 0.001≦x / y≦1, 3.0<z / y).

2. 2. The infrared curable ink composition according to claim 1, wherein the particle diameter of the infrared absorbing particles is 10 nm or more and 100 nm or less.

3. 3. The infrared curable ink composition according to claim 1, wherein the dispersed particle diameter of the infrared absorbing particles is 1 nm or more and 800 nm or less.

4. The infrared-curable ink composition according to claim 1 or 2, wherein the composite tungsten oxide has a hexagonal crystal structure.

5. 5. The infrared curable ink composition according to claim 4, wherein the M element comprises one or more elements selected from the group consisting of Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn.

6. 3. The infrared curable ink composition according to claim 1, wherein the surfaces of the infrared absorbing particles are coated with a compound containing one or more elements selected from the group consisting of Si, Ti, Zr, and Al.

7. The infrared curable ink composition according to claim 1 or 2, further comprising at least one pigment selected from the group consisting of organic pigments, inorganic pigments, and dyes.

8. The infrared curable ink composition according to claim 1 or 2, further comprising a dispersant.

9. The infrared curable ink composition according to claim 1 or 2, further comprising a solvent.

10. An infrared-cured product, which is a cured product of the infrared-curable ink composition according to claim 1 or 2.

11. a coating step of applying the infrared curable ink composition according to claim 1 or 2 to form a coated object; and a curing step of curing the coated material by irradiating it with infrared rays.

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