WO2016121801A1

WO2016121801A1 - Infrared-absorbent ink

Info

Publication number: WO2016121801A1
Application number: PCT/JP2016/052288
Authority: WO
Inventors: 文人小林; 渉吉住; 正太川▲崎▼; 芝岡　良昭; 優徳秋元; 博昭島根
Original assignee: 共同印刷株式会社
Priority date: 2015-01-27
Filing date: 2016-01-27
Publication date: 2016-08-04
Also published as: JPWO2016121801A1; JP6403806B2; TW201700641A

Abstract

The purpose of the present invention is to provide an infrared-absorbent ink which has excellent infrared absorbing properties and safety and can be used as a printing ink for forgery prevention. The infrared-absorbent ink according to the present invention includes: 1.0% by mass to 25% by mass of fine particles of at one or more types of infrared-absorbent material selected from composite tungsten oxides represented by the general formula M_xW_yO_z (M, W, O, x, y, and z in the formula being as defined in the specification) or tungsten oxides having a Magneli phase represented by the general formula W_yO_z (W, O, y, and z in the formula being as defined in the specification); and a vehicle. The vehicle includes a first solvent selected from vegetable oils or vegetable-oil-derived compounds, a second solvent selected from alcohols and having a boiling point of 180°C or lower, and a resin. The content of the second solvent is 2% by mass or less with respect to the mass of the infrared-absorbent ink.

Description

Infrared absorbing ink

The present invention relates to an infrared absorbing ink, a method for producing the infrared absorbing ink, and the like, and more particularly, to an infrared absorbing printing ink for preventing counterfeiting.

For the purpose of preventing counterfeiting, it has been studied to partially print on banknotes, securities, etc. using printing ink having infrared absorptivity.

Printing ink having infrared absorptivity is configured by adding an infrared absorber to commonly used ink. As infrared absorbers, infrared absorbing organic materials such as cyanine compounds and phthalocyanine compounds; or infrared absorbing inorganic materials such as tin-doped indium oxide (ITO) and antimony-doped tin oxide (ATO) are known. . In recent years, an infrared absorbing inorganic material has been used as the infrared absorbing agent in order to ensure the weather resistance of the infrared absorbing agent.

For example, Patent Document 1 proposes an infrared absorbing ink containing ITO as an infrared absorbing inorganic material.

Patent Document 2 proposes an anti-counterfeit infrared absorbing ink containing ATO as an infrared absorbing inorganic material.

By the way, Patent Document 3 describes a dispersion of tungsten-cesium composite oxide fine particles or tungsten oxide fine particles as a solar radiation shielding material having visible light transmission and infrared absorption.

JP 2000-309736 A JP 2010-006999 A JP 2005-187323 A

The ITO-containing infrared absorbing ink described in Patent Document 1 is less used than the ATO-containing infrared absorbing ink described in Patent Document 2 because indium is more expensive than antimony.

In the ATO-containing infrared absorbing ink described in Patent Document 2, antimony is cheaper than indium and cesium, has a light white color, and is commonly used in toluene, methyl isobutyl ketone (MIBK), methyl ethyl ketone (MEK), butyl acetate, and the like. Since it can be dispersed in a non-polar solvent for printing ink, it is widely used as an anti-counterfeit infrared absorbing ink having little influence on the color tone of other process inks.

However, the infrared absorbing inks described in Patent Documents 1 and 2 have insufficient contrast between the transmission or reflection of light in the visible light wavelength region and the transmission or reflection of light in the infrared light wavelength region. Further, there has been a problem that reading accuracy and the like are reduced in the printing portion of the anti-counterfeit printing ink.

Since the tungsten-cesium composite oxide fine particles and the tungsten oxide fine particles described in Patent Document 3 are dispersed in a nonpolar organic solvent such as toluene, a rubber blanket may be dissolved by the nonpolar organic solvent. It could not be used as a general printing ink, in particular as an offset printing ink.

When the tungsten-cesium composite oxide fine particles and tungsten oxide fine particles described in Patent Document 3 are simply added to and dispersed in the vegetable oil or the vegetable oil-derived compound used as a solvent for offset printing ink, the viscosity of the dispersion is increased. Has been found to increase.

The tungsten-cesium composite oxide fine particles described in Patent Document 3 were not expected to be used in general printing ink because cesium is extremely expensive. Further, Patent Document 3 does not describe the use of tungsten-cesium composite oxide fine particles and tungsten oxide fine particles for anti-counterfeit printing ink.

Therefore, the problem to be solved by the present invention is to have an infrared absorption and light resistance, a wavelength range that reflects visible light and a wavelength range that absorbs infrared light without dissolving a rubber blanket. It is to provide an infrared absorbing ink with a clear contrast between the two.

The present inventors have found that the above problems can be solved by the following invention.
[1]
General formula M _x W _y O _z {wherein M is H, He, alkali metal element, alkaline earth metal element, 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, One or more elements selected from the group consisting of Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I, W is tungsten, O is oxygen, x, y And z are each a positive number, 0 <x / y ≦ 1 and 2.2 ≦ z / y ≦ 3.0}, or a composite tungsten oxide represented by the general formula W _y O _z {wherein W is tungsten, O is oxygen, and y and z are positive numbers, respectively. And one or more infrared absorbing material fine particles selected from tungsten oxide having a magnetic phase represented by 2.45 ≦ z / y ≦ 2.999; and a vehicle;
Infrared absorbing ink containing the vehicle, wherein the vehicle is a first solvent selected from vegetable oils or compounds derived from vegetable oils, alcohols, ethers, esters, ketones, aromatic hydrocarbons, aliphatic A second solvent selected from the group consisting of hydrocarbons and glycol ethers and having a boiling point of 180 ° C. or lower and a resin, and the content of the second solvent is the infrared absorbing ink. Infrared absorbing ink that is 2% by mass or less based on the mass of
[2]
The infrared absorbing ink according to [1], wherein the dispersed particle diameter of the infrared absorbing material fine particles is 1 nm or more and 200 nm or less.
[3]
The infrared ray absorbing material according to [1] or [2], wherein the surface of the infrared absorbing material fine particles is coated with an oxide containing at least one selected from the group consisting of Si, Ti, Al and Zr. Ink.
[4]
The infrared-absorbing ink according to any one of [1] to [3], wherein the composite tungsten oxide has a hexagonal crystal structure or a hexagonal crystal structure.
[5]
The infrared absorbing ink according to any one of [1] to [4], wherein the first solvent is vegetable oil.
[6]
The infrared absorbing ink according to [5], wherein the vegetable oil is a drying oil or a semi-drying oil.
[7]
The infrared absorbing ink according to any one of [1] to [6], wherein the vehicle further includes a photopolymerization component.
[8]
The infrared absorbing ink according to any one of [1] to [7], further comprising a dispersant having in its structure a fatty acid soluble in the first solvent.
[9]
The infrared ray according to any one of [1] to [8], wherein a content of the infrared absorbing material fine particles is 1.0% by mass or more and 45% by mass or less with respect to a mass of the infrared absorbing ink. Absorbent ink.
[10]
The infrared absorbing ink according to any one of [1] to [9], which is used for preventing counterfeiting.
[11]
The infrared absorbing ink according to any one of [1] to [10], wherein the viscosity of the infrared absorbing ink is 0.002 Pa · s to 200 Pa · s.
[12]
[1] A method for obtaining a printed matter by flexographic printing, letterpress printing, offset printing, intaglio printing, gravure printing, screen printing or ink jet printing using the infrared absorbing ink according to any one of [1] to [11].
[13]
[1] to [11] A printed matter comprising an anti-counterfeit printing part printed with the infrared absorbing ink according to any one of [1] to [11].

The infrared-absorbing material fine particles used in the present invention are inorganic pigments, and are not easily deteriorated by light rays such as ultraviolet rays. Therefore, according to the present invention, it is possible to obtain a printing ink having high light resistance and infrared absorption. it can.

The fine particles of the infrared absorbing material used in the present invention have a clear contrast between the wavelength region that transmits or reflects visible light and the wavelength region that absorbs infrared light. Infrared absorbing ink for use can be provided. That is, according to the present invention, it is possible to obtain printed matter such as banknotes, securities, cards and the like excellent in infrared absorptivity, contrast between visible light reflectance and infrared reflectance, and design.

6 is a graph showing the contrast between the ink prints of Examples 2 and 3 and the commercially available ATO-containing ink prints with respect to the reflectance at wavelengths of 352 nm to 1600 nm. 3 is a graph showing the reflectance of indigo / red / yellow (CMY) process ink at wavelengths of 350 nm to 1500 nm.

<Infrared absorbing ink>
The infrared absorbing ink of the present invention includes infrared absorbing material fine particles selected from composite tungsten oxide or tungsten oxide having a magnetic phase, and a vehicle.

The ink of the present invention can be used to prevent forgery of printed matter by utilizing the infrared absorptivity of the infrared absorbing material fine particles.

The infrared absorbing ink according to the present invention includes infrared absorbing material fine particles and a vehicle, wherein the vehicle is one or more first solvents selected from vegetable oils or compounds derived from vegetable oils, alcohols, ethers, esters. A second solvent selected from the group consisting of a group, a ketone, an aromatic hydrocarbon, an aliphatic hydrocarbon, and a glycol ether, and having a boiling point of 180 ° C. or lower, and a resin, and The content of the solvent is 2% by mass or less with respect to the mass of the infrared absorbing ink.

In the ink of the present invention, the infrared-absorbing material fine particles are dispersed in the vehicle, preferably 10% by mass or more, 5% by mass or more of the infrared-absorbing material fine particles even after 1 hour without mixing. Sedimentation of 3% by mass or more, or 1% by mass or more does not occur. More preferably, in the ink of the present invention, the infrared absorbing material fine particles are first dispersed in the second solvent, the first solvent is added to the dispersion, and then the second solvent is added to 2% by mass or less. It is obtained by removing.

If desired, the infrared absorbing ink may further contain a dispersant having a fatty acid soluble in the first solvent in the structure as an auxiliary agent, and / or an auxiliary agent other than the dispersant, a colorant, and the like. Further may be included.

The ink of the present invention can be used as an oil-based ink or an oil-based / ultraviolet curable ink depending on the type of vehicle component.

Oil-based inks are inks that can be cured by oxidative polymerization of vehicle components. Generally, oil-based ink contains a solvent, resin, etc. as a vehicle component.

UV curable ink (hereinafter abbreviated as “UV ink”) is an ink that can be cured by photopolymerization of a vehicle component. In general, the UV ink contains a resin, a photopolymerizable monomer or oligomer, a photopolymerization initiator and the like as a vehicle component, but does not contain a volatile component such as a solvent.

The oil-based / ultraviolet-curing combined ink (hereinafter abbreviated as “oil-based / UV combined ink”) is an ink having curing characteristics of both oil-based ink and UV ink.

The infrared absorbing material fine particles, vehicle, auxiliary agent and colorant contained in the ink of the present invention will be described below.

[Infrared absorbing material fine particles]
The infrared absorbing material fine particles are at least one selected from a composite tungsten oxide represented by the following general formula (1) or a tungsten oxide having a magnetic phase represented by the following general formula (2):
M _x W _y O _z (1)
{Wherein M is H, He, alkali metal element, alkaline earth metal element, 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, One or more elements selected from the group consisting of Re, Be, Hf, Os, Bi, and I, W is tungsten, O is oxygen, and x, y, and z are positive numbers, respectively. Yes, 0 <x / y ≦ 1, and 2.2 ≦ z / y ≦ 3.0}
W _y O _z (2)
{Wherein W is tungsten, O is oxygen, y and z are positive numbers, and 2.45 ≦ z / y ≦ 2.999}
The alkali metal element is a Group 1 element of the periodic table excluding hydrogen, the alkaline earth metal element is a Group 2 element of the periodic table excluding Be and Mg, and the rare earth elements are Sc, Y and lanthanoids. It is an element.

As a method for producing the infrared-absorbing material fine particles, a method for producing a composite tungsten oxide or a tungsten oxide having a magnetic phase described in JP-A-2005-187323 can be used.

Element M is added to the composite tungsten oxide represented by the general formula (1). For this reason, free electrons are generated including the case of z / y = 3.0 in the general formula (1), the free electron-derived absorption characteristics are expressed in the near-infrared wavelength region, and the wavelength near 1000 nm. It is effective as a material that absorbs infrared rays.

In particular, from the viewpoint of improving optical properties and weather resistance as a near-infrared absorbing material, M element is one kind of Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe and Sn. The above is preferable, and Cs is particularly preferable.

Further, in the case of Cs _x W _y O _z (0.25 ≦ x / y ≦ 0.35, 2.2 ≦ z / y ≦ 3.0), the lattice constant is 7.4062 mm or more in the a-axis. In the following, it is preferable that the c-axis is 7.6106 mm or more and 7.6149 mm or less. When the lattice constant is within the above range, near-infrared absorbing fine particles having particularly excellent optical characteristics and weather resistance can be obtained.

It is preferable that the composite tungsten oxide represented by the general formula (1) is treated with a silane coupling agent because it is excellent in dispersibility, near infrared absorption, and transparency in the visible light wavelength region.

If the value of x / y indicating the addition amount of the element M is more than 0, a sufficient amount of free electrons is generated and a near infrared absorption effect can be sufficiently obtained. As the amount of the element M added increases, the supply amount of free electrons increases and the near-infrared absorption effect also increases. A value of x / y of 1 or less is preferable because generation of an impurity phase in the fine particle-containing layer can be avoided. The value of x / y is preferably 0.001 or more, 0.2 or more, or 0.30 or more, and this value is preferably 0.85 or less, 0.5 or less, or 0.35 or less. . The value of x / y is ideally 0.33.

In the general formulas (1) and (2), the value of z / y indicates the level of control of the oxygen amount. Since the composite tungsten oxide represented by the general formula (1) satisfies the relationship of z ≦ y 2.2 ≦ z / y ≦ 3.0, the tungsten oxide represented by the general formula (2) In addition to working the same oxygen control mechanism, there is a supply of free electrons due to the addition of element M even when z / y = 3.0. In the general formula (1), it is more preferable that the value of z / y satisfies the relationship of 2.45 ≦ z / y ≦ 3.0.

In addition, it originates in the raw material compound used at the time of manufacture of the composite tungsten oxide or tungsten oxide according to the present invention, and a part of oxygen atoms constituting the composite tungsten oxide or tungsten oxide is substituted with a halogen atom. However, there is no problem in the implementation of the present invention. Therefore, the composite tungsten oxide or tungsten oxide according to the present invention includes a case where a part of oxygen atoms is substituted with halogen atoms.

When the composite tungsten oxide represented by the general formula (1) has a hexagonal crystal structure or a hexagonal crystal structure, the transmission of the infrared-absorbing material fine particles in the visible light wavelength region is improved, In addition, the absorption in the near infrared wavelength region is improved, which is preferable. When the cation of the element M is added to the hexagonal voids, the transmission in the visible light wavelength region is improved, and the absorption in the near infrared wavelength region is improved. Here, generally, when an element M having a large ionic radius is added, a hexagonal crystal is formed. Specifically, hexagonal crystals are easily formed when an element having a large ionic radius such as Cs, K, Rb, Tl, In, Ba, Sn, Li, Ca, Sr, and Fe is added. However, the present invention is not limited to these elements, and elements other than these elements may be present as long as the additive element M exists in the hexagonal void formed by the WO ₆ unit.

When the composite tungsten oxide having a hexagonal crystal structure has a uniform crystal structure, the addition amount of the additive element M is preferably 0.2 or more and 0.5 or less in terms of x / y, more preferably 0.8. It is 30 or more and 0.35 or less, and is ideally 0.33. When the value of x / y is 0.33, it is considered that the additive element M is arranged in all of the hexagonal voids.

Besides hexagonal crystals, tetragonal or cubic tungsten bronzes also have a near infrared absorption effect. These crystal structures tend to change the absorption position in the near-infrared light wavelength region, and the absorption position tends to move to the longer wavelength side in the order of cubic <tetragonal <hexagonal. Further, it is in the order of hexagonal crystal <tetragonal crystal <cubic crystal that has little absorption in the visible light wavelength region. For this reason, it is preferable to use hexagonal tungsten bronze for applications that transmit more light in the visible light wavelength region and absorb more light in the near infrared light wavelength region.

In the tungsten oxide having the magnetic phase represented by the general formula (2), the so-called “magnetic phase” having a composition ratio in which the value of z / y satisfies the relationship of 2.45 ≦ z / y ≦ 2.999 is: Since it is chemically stable and has good absorption characteristics in the near infrared wavelength region, it is preferable as a near infrared absorbing material.

The infrared-absorbing material fine particles according to the present invention absorb a large amount of light in the near-infrared light wavelength region, particularly in the vicinity of a wavelength of 1000 nm, so that there are many things whose transmission color tone changes from blue to green. Further, the dispersed particle diameter of the infrared absorbing material fine particles can be selected depending on the purpose of use. First, when applying while maintaining transparency, it is preferable to have a dispersed particle size of 2000 nm or less. If the dispersed particle diameter is 2000 nm or less, the difference between the peak of the transmittance (reflectance) in the visible light wavelength region and the bottom of the absorption in the near-infrared light wavelength region becomes large. This is because the effect as a transparent near-infrared absorbing material can be exhibited. Furthermore, particles having a dispersed particle size smaller than 2000 nm do not completely block light due to scattering, can maintain visibility in the visible light wavelength region, and at the same time can efficiently maintain transparency.

Furthermore, when importance is attached to transparency in the visible light wavelength region, it is preferable to consider scattering by particles. Specifically, the dispersed particle diameter of the infrared absorbing material fine particles is preferably 200 nm or less, and more preferably 100 nm or less. If the dispersed particle size is small, geometrical scattering or Mie scattering is reduced, so that the scattering of light in the visible light wavelength region with a wavelength of 400 nm to 780 nm is reduced. As a result, the near-infrared absorbing film becomes like a frosted glass and is clear. This is because it is possible to avoid the loss of transparency. That is, when the dispersed particle diameter of the infrared absorbing material fine particles is 200 nm or less, the geometric scattering or Mie scattering is reduced and a Rayleigh scattering region is obtained. This is because, in the Rayleigh scattering region, the scattered light decreases in inverse proportion to the sixth power of the dispersed particle diameter, so that the scattering is reduced and the transparency is improved as the dispersed particle diameter decreases. Furthermore, when the dispersed particle diameter is 100 nm or less, the scattered light is preferably very small. From the viewpoint of avoiding light scattering, a smaller dispersed particle size is preferable. On the other hand, if the dispersed particle diameter is 1 nm or more, industrial production is easy.

The surface of the fine particles constituting the infrared absorbing material of the present invention is coated with an oxide containing one or more selected from the group consisting of Si, Ti, Al and Zr. It is preferable from the viewpoint of improving the weather resistance.

[Vehicle]
The vehicle is a medium for transferring the infrared-absorbing material fine particles and / or the colorant to the printing material and fixing the infrared-absorbing material fine particles and / or the coloring agent to the printing material after printing. The vehicle used in the present invention includes a solvent and a resin. The vehicle may further contain known vehicle components used for printing, such as photopolymerization components. The solvent, resin and photopolymerization component will be described below.

〔solvent〕
Examples of the solvent include a first solvent and a second solvent, and may optionally contain mineral oil or the like.

(First solvent)
The first solvent used in the present invention is insoluble in water, and is required not to dissolve a rubber blanket used in offset printing. Specifically, a solvent comprising at least one selected from vegetable oils and compounds derived from vegetable oils is used. Vegetable oils include dry oils such as linseed oil, sunflower oil and tung oil, semi-dry oils such as sesame oil, cottonseed oil, rapeseed oil, soybean oil and rice bran oil, and non-drying oils such as olive oil, coconut oil, palm oil and dehydrated castor oil. Used. Examples of the vegetable oil-derived compound include fatty acid monoesters and ethers obtained by directly esterifying a fatty acid of a vegetable oil with a monoalcohol.

The above-mentioned vegetable oil and the vegetable oil-derived compound have a double bond in the fatty acid of the fat that is a constituent component. This double bond reacts with oxygen in the air, so that a polymerization reaction between the double bonds proceeds. The coating film after the offset printing is solidified by bonding by a polymerization reaction between the oil molecules or a polymerization reaction between the oil molecules and the ink component for offset printing.

The solidification becomes faster as the number of double bonds in the fatty acid increases, but the double bond in the fatty acid is evaluated by the iodine value. That is, the solidification of the vegetable oil or the vegetable oil-derived compound is faster as the iodine value is higher. Specifically, the dry oil has an iodine value of 130 or more, semi-dry oil is 130 to 100, and non-dry oil is 100 or less. And when using for printing, vegetable oil is preferable and dry oils, such as linseed oil, sunflower oil, and tung oil whose iodine number is 130 or more are more preferable.

The viscosity of the first solvent used in the present invention is 1 mPa · s or more, 5 mPa · s or more, 10 mPa · s or more, 20 mPa · s or more, 30 mPa · s or more, 50 mPa · s or more, 80 mPa · s or more, or The viscosity may be 500 mPa · s or less, 300 mPa · s or less, 200 mPa · s or less, 150 mPa · s or less, or 100 mPa · s or less.

Here, in this specification, “viscosity” refers to the viscosity measured using a vibration viscometer VM100A-L (manufactured by CBC Materials).

(Second solvent)
The second solvent used in the present invention is a solvent suitable for the step of pulverizing the infrared absorbing material according to the present invention into fine particles and dispersing it in the solvent. Specifically, the second solvent is an alcohol such as ethanol, propanol, butanol, isopropyl alcohol, isobutyl alcohol or diacetone alcohol, an ether such as methyl ether, ethyl ether or propyl ether, an ester, acetone or methyl ethyl ketone. , Ketones such as diethyl ketone, cyclohexanone, ethyl isobutyl ketone, methyl isobutyl ketone, aromatic hydrocarbons such as toluene, xylene, benzene, aliphatic hydrocarbons such as normal hexane, heptane, cyclohexane, propylene glycol monomethyl ether acetate And various organic solvents such as glycol ethers such as propylene glycol monoethyl ether, and have a boiling point of 180 ° C. or lower. The second solvent is preferably a solvent that is compatible with the first solvent.

Among these, alcohols, aliphatic hydrocarbons, and glycol ethers are the second solvents that have low health hazards to the human body and are preferable from the viewpoint of safety or operability in the process. Further, methyl isobutyl ketone or toluene is a second solvent that is excellent in workability and is preferable from the viewpoint of improving productivity.

However, since the second solvent may dissolve a rubber blanket to which the ink is transferred during offset printing, the offset solvent is required to have a content of a predetermined amount or less. . Specifically, the content is preferably 5.0% by mass or less, 2.0% by mass or less, 1.5% by mass or less, or 1.0% by mass or less. However, the second solvent may be contained in the ink at a content of 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass or more, or 1.0% by mass or more.

Therefore, after the step of pulverizing the infrared absorbing material according to the present invention into fine particles and dispersing in the solvent is completed, the content of the second solvent is preferably sufficiently reduced.

Specifically, it is conceivable to use a low-boiling solvent as the second solvent, provide a difference in boiling point with the first solvent, and reduce the content of the second solvent by heating distillation or the like. . If solvent substitution is performed by heating distillation, the boiling point of the second solvent may be 180 ° C. or lower, or 150 ° C. or lower. The boiling point of the first solvent is higher than the boiling point of the second solvent, and may be higher than 150 ° C. or higher than 180 ° C.

The viscosity of the second solvent used in the present invention is 0.1 mPa · s or more, 0.2 mPa · s or more, 0.3 mPa · s or more, 0.5 mPa · s or more, 0.8 mPa · s or more, or It may be 1.0 mPa · s or more, and the viscosity is 10 mPa · s or less, 5.0 mPa · s or less, 3.0 mPa · s or less, 2.0 mPa · s or less, 1.5 mPa · s or less, or It may be 1.0 mPa · s or less.

(mineral oil)
The ink of the present invention may contain a mineral oil as a solvent in consideration of the drying property of the ink, the permeability to the printing material, and the like. Examples of the mineral oil include spindle oil, machine oil, white kerosene, and non-aromatic petroleum solvent. In particular, the mineral oil is preferably a non-aromatic petroleum solvent that is incompatible with water and has a boiling point of 180 ° C. or higher. The boiling point of the non-aromatic petroleum solvent is preferably 200 ° C. or higher. Examples of the non-aromatic petroleum solvent include n-dodecane mineral oil. Specific examples of non-aromatic petroleum solvents include No. 0 Solvent, AF Solvent No. 5, AF Solvent No. 6, AF Solvent No. 7 (all manufactured by Nippon Oil Corporation).

〔resin〕
As the resin used in the present invention, a known resin used for printing may be used. For example, a resin contained in oil-based ink or a resin contained in UV ink may be used.

The resin may be a natural resin or a synthetic resin. The resin may be a homopolymer or a copolymer. In order to ensure the viscosity of the oil-based ink, the resin is preferably solid. When the resin is used as a binder for UV ink, the resin preferably has a weight average molecular weight of about 1000 to about 3,000,000.

Examples of natural resins include rosin, cocoon, shellac, and gilsonite. Generally, natural resins contain a resin acid as a non-volatile component. Examples of the resin acid include abietic acid, neoabietic acid, ballastric acid, pimaric acid, isopimaric acid, dehydroabietic acid, chelolic acid, and aloyritic acid.

Examples of the synthetic resin include rosin, phenol resin, modified alkyd resin, polyester resin, petroleum resin, rosin modified maleic resin and other maleic resins, cyclized rubber, and other synthetic resins.

Rosin is obtained by refining rosin and is roughly divided into three types: gum rosin, wood rosin and tall oil rosin. In general, rosin has a softening point of 70-80 ° C. and an acid number of 170-180. The rosin may be modified.

Phenolic resins are resins obtained by condensation of phenol and aldehyde, and are roughly classified into four types: novolac type resin, resol type resin, 100% phenol resin and modified phenol resin. Considering the resistance of the vehicle, 100% phenolic resin or modified phenolic resin is preferable.

A 100% phenol resin is a resin obtained by condensing an alkylphenol and formaldehyde in the presence of an acid or an alkali catalyst.

The modified phenolic resin is a resin obtained by reacting a condensate of phenol and formalin with a modifying component such as rosin, rosin ester or drying oil. In particular, a modified phenolic resin using rosin as a modifying component is called a rosin-modified phenolic resin and is generally used for offset printing ink.

In order to adjust the water resistance, setting property, tackiness or pigment dispersibility of the ink, the rosin-modified phenolic resin preferably has an acid value of 5 to 40 and / or a softening point of 130 to 190 ° C.

The modified alkyd resin is a resin obtained by reacting a condensate of a polybasic acid and a polyhydric alcohol with a modified component such as fatty acid, rosin, drying oil or semi-drying oil.

Examples of the polybasic acid include phthalic anhydride and isophthalic acid. Examples of the polyhydric alcohol include glycerin and pentaerythritol. Examples of fatty acids include linseed oil, dehydrated castor oil, soybean oil, and the like.

Specific examples of the modified alkyd resin include phenol-modified alkyd resin, epoxy-modified alkyd resin, urethane-modified alkyd resin, silicone-modified alkyd resin, acrylic-modified alkyd resin, vinyl-modified alkyd resin, neutralized acid alkyd resin, and the like.

Polyester resin is a polycondensate of polyvalent carboxylic acid and polyalcohol. Examples of the polyester resin include unsaturated polyester resin and polyethylene terephthalate.

Petroleum resin is a resin obtained by polymerizing an unsaturated olefin having 5 or more carbon atoms. In general, petroleum resins have a softening point of 80-130 ° C.

The rosin-modified maleic resin is a resin obtained by reacting rosin, maleic anhydride and a polyhydric alcohol. Examples of the polyhydric alcohol include glycerin and pentaerythritol. The rosin-modified maleic resin preferably has a softening point of 80 to 140 ° C. and / or an acid value of 15 to 200.

Cyclized rubber is a resin obtained by treating natural rubber with tin chloride. The cyclized rubber has a softening point of 120 to 140 ° C. and is excellent in solubility in a drying oil or a solvent.

Examples of other synthetic resins include diallyl phthalate polymer, poly (meth) acrylic acid, poly (meth) acrylic acid ester, polyester-melamine polymer, styrene- (meth) acrylic acid copolymer, styrene- (meth) acrylic acid- Alkyl (meth) acrylate copolymer, styrene-maleic acid copolymer, styrene-maleic acid-alkyl (meth) acrylate copolymer, styrene-maleic acid half ester copolymer, vinylnaphthalene- (meth) acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer, And salts thereof.

The resins listed above can be used alone or in combination of two or more.

(Photopolymerization component)
The photopolymerization component used in the present invention includes a monomer, an oligomer, a photopolymerization initiator, and the like.

(Monomer / Oligomer)
The monomer may be a compound having an ethylenically unsaturated bond conventionally used for photopolymerization. Moreover, an oligomer is obtained by oligomerizing the compound which has an ethylenically unsaturated bond.

Oligomers are resins that govern the basic physical properties of UV ink. On the other hand, the monomer mainly acts as a diluent and can be used to adjust properties such as ink viscosity, curability and adhesion.

Examples of compounds having an ethylenically unsaturated bond include (meth) acrylic acid compounds; maleic acid compounds; urethane-based, epoxy-based, polyester-based, polyol-based, vegetable oil-based compounds and the like. Examples include compounds having a heavy bond.

Specifically, examples of the compound having an ethylenically unsaturated bond include epoxy (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate, silicone (meth) acrylate, acrylated amine, and acrylic saturation. Resin and acrylic acrylate, acid anhydride addition acrylate of bisphenol A type epoxy (meth) acrylate, acid anhydride addition acrylate of phenol novolac epoxy (meth) acrylate, acid addition addition of dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate An acrylate having a carboxyl group obtained by adding an acid anhydride to an acrylate having a hydroxyl group, such as an acrylate, or a carboxylic acid obtained by adding an acid anhydride to a urethane acrylate having a hydroxyl group. Acrylates having a hexyl group, polyethylene glycol diacrylate, polypropylene glycol diacrylate, polyglycerol epoxy acrylates, water-soluble acrylates such as polyglycerol acrylate, and acryloyl morpholine.

Among these, a compound that is compatible with the resin and has a highly lipophilic ethylenically unsaturated bond is preferable, for example, a compound having an ethylenically unsaturated bond having a long-chain alkyl group having 6 to 24 carbon atoms, A compound having an ethylenically unsaturated bond modified with polybutylene glycol, a compound having an ethylenically unsaturated bond modified with vegetable oil, and the like are preferable.

(Photopolymerization initiator)
The photopolymerization initiator is a compound that generates radicals such as active oxygen when irradiated with ultraviolet rays. The ink of the present invention may contain a known photopolymerization initiator used for printing.

Examples of the photopolymerization initiator include acetophenone, α-aminoacetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and benzyldimethyl ketal. 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-methylpropyl) ketone, 4- (2- Hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2- Dimethylamino-1- (4-morpholinophenyl) -butanone Which acetophenones; benzoins such as beizoin, beizoin methyl ether, benzoin ethyl ether, benzoin-n-propyl ether, beizoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, benzoin dimethyl ketal, benzoin peroxide Acyl phosphine oxides such as 2,4,6-trimethoxybenzoin diphenylphosphine oxide; benzyl and methylphenyl-glyoxyesters; benzophenone, methyl-4-phenylbenzophenone, o-benzoylbenzoate, 2-chlorobenzophenone, 4 , 4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylic-benzo Benzophenones such as phenone, 3,3′4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 3,3′-dimethyl-4-methoxybenzophenone; 2-methylthioxanthone, 2-isopropylthioxanthone, 2,4 -Thioxanthones such as dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone; Aminobenzophenones such as Michler ketone, 4,4'-diethylaminobenzophenone; Tetramethylthiuram monosulfide; Azobis Examples thereof include isobutyronitrile; di-tert-butyl peroxide; 10-butyl-2-chloroacridone; 2-ethylanthraquinone; 9,10-phenanthrenequinone;

Further, a photopolymerization initiation assistant such as ethyl 4-dimethylaminobenzoate or isoamyl 4-dimethylaminobenzoate may be used in combination with the photopolymerization initiator.

[Adjuvant]
The ink of the present invention may contain known auxiliary agents used in printing, such as dispersants, crosslinking agents, drying accelerators, waxes, extender pigments, and other additives. The ink of the present invention preferably contains a dispersant having a fatty acid soluble in the first solvent in the structure as an auxiliary agent.

[Dispersant]
The dispersant for dispersing the infrared absorbing material fine particles in the vehicle is not limited as long as it is soluble in the first solvent and can disperse the infrared absorbing material fine particles. In particular, it is preferable to use a dispersant having a fatty acid structure soluble in the first solvent because the dispersion stability of the fine particles of the infrared absorbing material is excellent in the first solvent.

In order to disperse the colorant other than the fine particles of the infrared absorbing material in the vehicle, a dispersant other than the dispersant having a fatty acid soluble in the first solvent in the structure, for example, a compound derived from the pigment skeleton of the colorant Etc. may be used.

In addition, it is preferable that the addition amount of the dispersing agent concerning this invention is 30 weight part or more with respect to 100 weight part of infrared rays absorbing material microparticles | fine-particles. When using a commercially available dispersing agent, it is preferable that the said dispersing agent does not contain the solvent which may melt | dissolve the rubber blanket for offset printing. Therefore, the content of the nonvolatile content in the dispersant (after heating at 180 ° C. for 20 minutes) is preferably high, for example, 95% or more.

[Crosslinking agent]
A crosslinking agent or gelling agent can be added to the vehicle to crosslink or gel the resin.

Examples of the cross-linking agent include isocyanate compounds such as tolylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, tetramethylxylylene diisocyanate, polymethylene polyphenyl polyisocyanate; trimethylolpropane-tris-β-N-aziridini Aziridine compounds such as lupropionate and pentaerythritol propane-tris-β-N-aziridinylpropionate; epoxy compounds such as glycerol polyglycidyl ether and trimethylolpropane polyglycidyl ether; aluminum triisopropoxide, mono- sec-Butoxyaluminum diisopropoxide, Aluminum tri-sec-butoxide, Ethyl acetoacetate Examples include aluminum alcoholates such as trialuminum diisopropoxide and aluminum trisethyl acetoacetate; and aluminum chelates such as aluminum chelate compounds.

[Drying accelerator]
Examples of the drying accelerator include a fatty acid metal salt, an organic carboxylic acid metal salt, and an inorganic acid metal salt contained in the first solvent.

Examples of the organic carboxylic acid for forming the drying accelerator include acetic acid, propionic acid, butyric acid, isopentanoic acid, hexanoic acid, 2-ethylbutyric acid, naphthenic acid, octylic acid, nonanoic acid, decanoic acid, and 2-ethylhexane. Acid, isooctanoic acid, isononanoic acid, lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, neodecanoic acid, versatic acid, secanoic acid, tall oil fatty acid, linseed oil fatty acid, soybean oil fatty acid, dimethylhexanoic acid, Examples include 3,5,5-trimethylhexanoic acid and dimethyloctanoic acid.

The organic carboxylic acid is preferably a fatty acid contained in a drying oil or a semi-drying oil. When the drying accelerator is used as a liquid dryer, the organic carboxylic acid is preferably naphthenic acid. On the other hand, when the drying accelerator is used as a paste dryer, the organic carboxylic acid is preferably acetic acid.

Examples of inorganic acids include hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, boric acid, hydrofluoric acid, and the like. When the drying accelerator is used as a paste dryer, the inorganic acid is preferably boric acid.

Examples of the metal for forming the metal salt of the acid include calcium, cobalt, lead, iron, manganese, zinc, vanadium, cerium, zirconium, sodium and the like.

〔wax〕
Wax is an auxiliary agent for preventing the printed surface from being scratched. Specifically, the wax can impart properties such as friction resistance, anti-blocking properties, slipperiness, and anti-scratch properties to the surface of the ink coating. The ink of the present invention may contain a known wax used for printing.

Examples of waxes include natural waxes such as carnauba wax, wax, lanolin, montan wax, paraffin wax, and microcrystalline wax; Fischer Trops wax, polyethylene wax, polypropylene wax, polytetrafluoroethylene wax, polyamide wax, silicone compound Synthetic waxes such as; fluorinated products of synthetic waxes.

[External pigment]
The extender pigment is a pigment used for adjusting the viscosity of the ink, and has a low refractive index and a low coloring power. Accordingly, extender pigments are preferably used when the viscosity of the ink is high and wiping is difficult. The ink of the present invention may contain a known extender pigment used for printing.

Examples of extender pigments include barium sulfate, calcium carbonate, calcium sulfate, kaolin, talc, silica, corn starch, titanium dioxide, and mixtures thereof.

[Other additives]
In the ink of the present invention, a polymerization inhibitor such as phenothiazine and t-butylhydroxytoluene; a drying inhibitor; an antioxidant; a leveling aid; an anti-set-off agent; or a nonionic surfactant, if desired. A surfactant may be included.

[Colorant]
The colorant is a component that adds color to the ink. In addition to the composite tungsten oxide or tungsten oxide having a magnetic layer described above, the ink of the present invention may contain a known colorant used for printing. Examples of the colorant include inorganic pigments, organic pigments, dyes, organic pigments for toners, and the like.

Examples of inorganic pigments include chrome yellow, zinc yellow, bitumen, barium sulfate, cadmium red, titanium oxide, zinc white, alumina white, calcium carbonate, ultramarine, graphite, aluminum powder, bengara, barium ferrite, copper and zinc alloy. Examples thereof include powder, glass powder, and carbon black.

Examples of organic pigments include soluble azo pigments such as β-naphthol pigments, β-oxynaphthoic acid pigments, β-oxynaphthoic acid anilide pigments, acetoacetate anilide pigments, and pyrazolone pigments; β-naphthol pigments Insoluble azo pigments such as pigments, β-oxynaphthoic acid anilide pigments, acetoacetanilide monoazos, acetoacetanilide disazos, pyrazolone pigments; copper phthalocyanine blue, halogenated (eg chlorine or brominated) copper phthalocyanine blue, Phthalocyanine pigments such as sulfonated copper phthalocyanine blue and metal-free phthalocyanine; quinacridone pigments, dioxazine pigments, selenium pigments (pyrantron, anthrone, indanthrone, anthrapyrimidine, flavantron, thioindigo, anthraquinone , Perinone, perylene, etc.), isoindolinone pigments, metal complex pigments, quinophthalone pigments, and other polycyclic or heterocyclic pigments.

Here, the organic pigment includes a lake pigment. In general, a lake pigment is obtained by dyeing a dye on an inorganic pigment or extender, and the lake pigment also has water insolubility according to the water insolubility of the inorganic pigment or extender. Examples of lake pigments include the fanal (FANAL (registered trademark)) color series available from BASF.

Examples of the dye include azo dyes, complex salts of azo dyes and chromium, anthraquinone dyes, indigo dyes, phthalocyanine dyes, xanthene dyes, thiazine dyes, and the like.

The organic dye for toner is an organic dye that can be contained in the toner, and has charging properties in addition to the general characteristics of the colorant. As the organic pigment for toner, a dye or an organic pigment may be used, but a dye is preferred from the viewpoint of transparency and coloring power.

Furthermore, in addition to the colorant described above, other functional materials such as functional pigments and functional dyes may be blended in the ink used in the present invention. Here, the functional material may be inorganic or organic, and may be an additive that imparts functionality to the ink.

Examples of functional materials include chromic materials, magnetic pigments, ultraviolet absorbers, optically variable materials, pearl pigments, and the like. In general, a chromic material is a material that develops a color in response to energy such as light, heat, electricity, and fades when the energy is blocked or lost. Examples of the chromic material include fluorescent pigments, excited luminescent pigments, temperature-sensitive color changing materials, photochromic materials, and stress luminescent materials.

The colorants listed above can be used alone or in combination of two or more.

<Composition and viscosity of infrared absorbing ink>
The content of the infrared absorbing material fine particles in the infrared absorbing ink is preferably 1.0% by mass or more, 1.8% by mass or more, 2.5% by mass or more, or 3.0% by mass or more, This content may be 45 mass% or less, 37.5 mass% or less, 25 mass% or less, 20 mass% or less, 15 mass% or less, 9.0 mass% or less, or 8.0 mass% or less. preferable.

The content of the dispersant in the infrared absorbing ink is preferably 0.25% by mass or more, 0.5% by mass or more, or 1.0% by mass or more, and the content is 13% by mass or less, 10 It is preferable that it is mass% or less or 8 mass% or less.

The viscosity of the infrared absorbing ink may be 0.002 Pa · s or more, 0.02 Pa · s or more, 0.2 Pa · s or more, 2 Pa · s or more, or 5 Pa · s or more. It may be s or less, 150 Pa · s or less, or 100 Pa · s or less.

The solvent, resin, and photopolymerization component as the vehicle may be included in the infrared absorbing ink in such an amount that the viscosity of the infrared absorbing ink becomes 0.002 Pa · s to 200 Pa · s. However, when the infrared absorbing ink contains the first solvent and the second solvent, the content of the second solvent in the infrared absorbing ink is 2% by mass or less regardless of the presence or absence of the dispersant. is there.

When the infrared absorbing ink is an oil ink, the blending ratio of each component contained in the oil ink is such that when the viscosity of the oil ink is adjusted to about 5 to 100 Pa · s, the infrared absorbing material fine particles are 1. 0 to 45% by weight, vehicle is 20 to 85% by weight, colorant is 0 to 20% by weight, and auxiliary is 0.25 to 25% by weight.

When the infrared absorbing ink is an oil / UV combination ink, the blending ratio of each component contained in the oil / UV combination ink is adjusted when the viscosity of the oil / UV combination ink is adjusted to several hundred Pa · s. The vehicle for oil-based ink containing a solvent and a resin is 25 to 50% by mass, the vehicle for UV ink containing a resin and a photopolymerization component is 25 to 50% by mass, and the fine particles of infrared absorbing material are 1.0 to 45% by mass. %, 0 to 20% by weight of the colorant, and 0.25 to 20% by weight of the auxiliary agent.

<Method for producing infrared absorbing ink>
An embodiment of the method for producing the ink of the present invention comprises the following steps:
(A) Dispersing the infrared absorbing material fine particles in a solvent to obtain a dispersion; and (b) mixing the dispersion with a vehicle to obtain an ink.

The method for performing step (a) may be any method that uniformly disperses the infrared-absorbing material fine particles in a solvent, and can be selected from any dispersion method. Specifically, step (a) is preferably performed by a wet medium mill such as a bead mill or a ball mill.

In step (b), a resin is added as a vehicle component to the dispersion obtained in step (a), and if necessary, a group consisting of fine particles of infrared absorbing material, a vehicle component such as a solvent, an auxiliary agent, and a colorant. Is carried out in order to adjust the final composition, viscosity, color tone or dryness of the ink by adding at least one selected from In step (b), a photopolymerization component may be added to the mixture or dispersion, and other materials may be added as desired to obtain the oil-based / UV combined ink of the present invention. Each component contained in the infrared absorbing ink can be finally adjusted to a desired blending ratio by the step (b). Step (b) can be carried out with a mixer, a meat mill, or the like.

The dispersion obtained in step (a) is preferably an infrared absorbing fine particle dispersion described later.

[Infrared absorbing fine particle dispersion]
The infrared-absorbing fine particle dispersion contains the infrared-absorbing material fine particles, the first solvent, and the second solvent, and the content of the second solvent in the infrared-absorbing fine particle dispersion is 5.0. It is below mass%.

The infrared absorbing material fine particles, the first solvent, and the second solvent contained in the infrared absorbing fine particle dispersion are the infrared absorbing material fine particles and the first solvent described above for the infrared absorbing ink of the present invention. And a second solvent, respectively.

Since the first solvent has a high viscosity, it may be difficult to disperse the infrared-absorbing material fine particles in the first solvent in the step (a). When the first solvent has a viscosity (24 ° C.) of 180 mPa · s or more, such as tung oil, it is difficult to disperse the infrared-absorbing material fine particles only in the first solvent. Therefore, specifically, the infrared-absorbing fine particle dispersion is preferably produced by the method (A) or (B) for producing the infrared-absorbing fine particle dispersion described later.

[Method for producing infrared-absorbing fine particle dispersion (A)]
The method (A) for producing the infrared-absorbing fine particle dispersion includes the following steps in the following order:
(A-1) mixing the infrared-absorbing material fine particles into a second solvent and dispersing the mixture with a wet medium mill to obtain a first dispersion;
(A-2) adding a first solvent to the first dispersion and mixing to obtain a second dispersion; and (A-3) a second solvent from the second dispersion. Removing the second solvent until the content of is less than 5.0% by mass.

The method of performing step (A-1) can be arbitrarily selected as long as it is a method of uniformly dispersing the infrared absorbing material fine particles in the second solvent. Specifically, it is preferable to use a wet medium mill such as a bead mill or a ball mill. The boiling point of the second solvent is 180 ° C. or lower, preferably 150 ° C. or lower.

If the concentration of the infrared-absorbing material fine particles in the first dispersion is 5% by mass or more, the productivity when producing the printing ink described later is excellent. On the other hand, if the concentration of the infrared absorbing material fine particles is 60% by mass or less, the viscosity of the first dispersion liquid does not increase, and the infrared absorbing material fine particles can be easily pulverized and dispersed. From such a viewpoint, the content of the infrared absorbing material fine particles in the first dispersion is 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, or 25% by mass or more. The content is 75% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, 58% by mass or less, 56% by mass or less, 54% by mass or less, or 52% by mass or less. Is preferred.

In step (A-2), it is preferable to select a solvent compatible with each other as the first solvent and the second solvent. In step (A-2), the infrared absorption finally obtained when 2.5 parts by weight or more of the first solvent is used with respect to 100 parts by weight of the infrared absorbing material fine particles contained in the first dispersion. This is preferable because the fluidity of the fine particle dispersion is maintained, the recovery is facilitated, and the productivity is maintained. The first solvent has a boiling point higher than that of the second solvent, and is preferably 150 ° C. or higher or 180 ° C. or higher.

On the other hand, in step (A-2), it is finally obtained that 270 parts by weight or less of the first solvent is used with respect to 100 parts by weight of the infrared absorbing material fine particles contained in the first dispersion. This is preferable because the concentration of the infrared absorbing material fine particles in the infrared absorbing fine particle dispersion is ensured. For this reason, for example, it is possible to avoid an excessive addition of the infrared-absorbing fine particle dispersion to the offset printing ink, and the viscosity of the ink can be ensured. As a result, the viscosity of the ink is not greatly changed, viscosity adjustment is unnecessary, the process is simplified, and an increase in manufacturing cost can be avoided.

From the above viewpoint, at the time of mixing the first dispersion and the first solvent in step (A-2), the first weight of the infrared-absorbing material fine particles contained in the first dispersion is The solvent is preferably 2.5 to 270 parts by weight, more preferably 70 to 270 parts by weight, and still more preferably 92 to 204 parts by weight.

When it is desired to further suppress the increase in the viscosity of the first and second dispersions in step (A-2), it is also preferable to add the above-described dispersant to the first and / or second dispersion. In that case, the dispersant may be added to the first and / or second dispersion by the following method:
A method of adding a dispersant to the second solvent in advance,
A method of adding a dispersant to the first solvent in advance to obtain a dispersant solution and adding the dispersant solution to the first dispersion, or in parallel with the addition of the first solvent to the first dispersion And adding a dispersant to the first dispersion.
In addition, when using the method of adding a dispersing agent to a 2nd solvent previously, the dispersing agent soluble in a 2nd solvent is selected.

Step (A-3) can be performed by a heating distillation method using a difference in boiling points between the first solvent and the second solvent. Furthermore, the reduced pressure heating distillation including the reduced pressure operation is preferable from the viewpoints of safety, energy cost, and quality stabilization.

[Production method of infrared absorbing fine particle dispersion (B)]
The method (B) for producing the infrared-absorbing fine particle dispersion includes the following steps in the following order:
(B-1) A step of mixing the first solvent and the second solvent to obtain a mixed solvent;
(B-2) a step of mixing the infrared-absorbing material fine particles in the mixed solvent, dispersing, and preferably dispersing with a wet medium mill to obtain a third dispersion; and (B-3) Removing the second solvent from the third dispersion until the content of the second solvent is 5.0% by mass or less.

In step (B-1), one or more types of the first solvent and one or more types of the second solvent are mixed. As the first solvent and the second solvent, those compatible with each other are preferably selected.

The method of performing step (B-2) can be arbitrarily selected as long as it is a method of uniformly dispersing the infrared absorbing material fine particles in the mixed solvent. Specifically, it is preferable to use a wet medium mill such as a bead mill or a ball mill.

If the concentration of the infrared-absorbing material fine particles in the third dispersion is 5% by mass or more, the productivity is excellent when producing the printing ink described later. On the other hand, when the concentration of the infrared-absorbing material fine particles is 60% by mass or less, the viscosity of the third dispersion liquid does not increase, and the operation of pulverizing and dispersing the infrared-absorbing material fine particles is easy. From such a viewpoint, the content of the infrared absorbing material fine particles in the third dispersion is 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, or 25% by mass or more. The content is 75% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, 58% by mass or less, 56% by mass or less, 54% by mass or less, or 52% by mass or less. Is preferred.

In the step (B-2) or after the step (B-2), when it is desired to further suppress the increase in the viscosity of the mixed solvent containing the infrared absorbing material fine particles, it is also preferable to add the above-described dispersant. In that case, a dispersing agent may be added to the mixed solvent before the dispersing operation.

Step (B-3) can be performed by a heating distillation method using a difference in boiling points between the first solvent and the second solvent. Furthermore, the reduced pressure heating distillation method including a reduced pressure operation is preferable from the viewpoints of safety, energy cost, and quality stabilization.

Specifically, in the vacuum heating distillation method, the second dispersion or the third dispersion is distilled under reduced pressure while stirring, and the second solvent is separated from the third dispersion. Examples of the apparatus used for the vacuum heating distillation method include a vacuum stirring type dryer, but any apparatus having the above functions may be used, and the apparatus is not particularly limited.

The temperature during the heating distillation is preferably 35 ° C. or higher, 40 ° C. or higher, or 60 ° C. or higher, and this temperature is preferably 200 ° C. or lower, 150 ° C. or lower, or 120 ° C. or lower. If the temperature at the time of heating distillation is 35 degreeC or more, the removal rate of a solvent can be ensured. If the temperature at the time of heating distillation is 200 ° C. or lower, alteration of the dispersant can be avoided.

When the heating distillation operation and the decompression operation are used in combination, the degree of vacuum is preferably −0.05 MPa or less, more preferably −0.06 MPa or less in terms of gauge pressure. When the gauge pressure is −0.05 MPa or less, the solvent removal rate is fast and the productivity is good.

By using the reduced pressure heating distillation method, the removal efficiency of the second solvent is improved and the infrared absorbing fine particle dispersion is not exposed to a high temperature for a long time. Aggregation of the absorbent material fine particles or deterioration of the first solvent does not occur, which is preferable. Furthermore, by using the above-mentioned reduced pressure heating distillation method, the productivity of the infrared absorbing fine particle dispersion is increased, and it is easy to recover the evaporated organic solvent.

[Infrared absorbing fine particle dispersion composition and viscosity]
An infrared-absorbing fine particle dispersion can be obtained by the production method (A) or (B) described above. The higher the final concentration of the infrared-absorbing material fine particles in the infrared-absorbing fine particle dispersion, the easier the ink preparation and the better. On the other hand, when this concentration becomes too high, the fluidity of the infrared-absorbing fine particle dispersion is lowered. Therefore, in the production method (A) or (B), the produced infrared-absorbing fine particle dispersion only needs to have fluidity that can be recovered. From such a viewpoint, the final content of the infrared absorbing material fine particles in the infrared absorbing fine particle dispersion is 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, or 25% by mass. The content is preferably 75% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, 58% by mass or less, 56% by mass or less, 54% by mass or less, or 52% by mass or less. It is preferable that it is below mass%.

The dispersion particle diameter of the infrared absorbing material fine particles in the infrared absorbing fine particle dispersion can be arbitrarily controlled by the processing time of the wet medium mill. By extending the treatment time, the dispersed particle diameter of the infrared absorbing material fine particles can be reduced.

The lower limit of the viscosity of the infrared-absorbing fine particle dispersion depends on the viscosity of the first solvent used, that is, the viscosity of the vegetable oil or the vegetable oil-derived compound. For example, the viscosity of sunflower oil (24 ° C.) is 50 mPa · s, and the viscosity of linseed oil (24 ° C.) is 40 mPa · s.

The upper limit of the viscosity of the infrared-absorbing fine particle dispersion may be arbitrarily determined according to the content of the infrared-absorbing material fine particles, but as the upper limit of the viscosity suitable for producing a printing ink described later, It is preferably 100 Pa · s or less.

A binder may be further added to the infrared absorbing fine particle dispersion. The binder is not particularly limited, and examples thereof include resins used as vehicles, such as polyamide, polyurethane, nitrocellulose, acrylic resin, maleic acid resin, rosin, and modified rosin.

<Printing ink>
The infrared absorbing ink of the present invention can be used as a general printing ink. For example, the infrared absorbing ink of the present invention can be used as flexographic ink, letterpress printing ink, offset printing ink, intaglio printing ink, gravure printing ink, screen printing ink, inkjet printing ink, and the like.

Among these, in order to prevent forgery of printed matter, the infrared absorbing ink of the present invention is preferably used as an offset printing ink, an intaglio printing ink or a screen printing ink. The intaglio printing ink can be used for press printing using a direct printing plate surface or an etching plate surface.

The infrared absorbing ink of the present invention can provide a printed matter having a printing part by printing on a substrate. Examples of the base material include paper base materials such as fine paper, coated paper, art paper, cast coated paper, foil paper, recycled paper, impregnated paper, variable information paper, etc .; film base materials such as polyester film, polypropylene film, Polystyrene film, vinyl chloride film, polyimide film, variable information film or the like; or a cloth substrate such as woven cloth or non-woven cloth may be used. The printed matter may be banknotes, securities, cards or the like.

The printing ink of the present invention preferably contains 2 to 50% by mass of the infrared absorbing fine particle dispersion described above. The printing ink of the present invention may contain 2.0% by mass or less of the second solvent described above.

Since the ink of the present invention has infrared absorptivity, it can be used for various information management by printing the printing ink of the present invention in an arbitrary pattern and reading it with a near-infrared light determining machine or the like.

For example, when a printed matter obtained by printing the ink of the present invention on a substrate is observed with an infrared light detector such as an infrared camera, the portion on which the ink of the present invention is printed absorbs infrared rays, Since it is displayed blacker than the portion of, the infrared absorption contrast can be detected. Therefore, the authenticity of the printed matter can be determined by comparing the predetermined infrared absorption contrast with the infrared absorption contrast of the observation target.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not necessarily limited to these Examples.
The optical properties (transmittance, reflectance) of the film and the printed material according to this example were measured using a spectrophotometer U-4000 (manufactured by Hitachi, Ltd.) unless otherwise specified. The spectral transmittance was measured according to JIS R 3106.

<Preparation of infrared absorbing fine particle dispersion>
(Comparative Example 1)
As near-infrared absorbing material fine particles, hexagonal Cs _0.33 WO ₃ (a-axis 7.4075 軸, c-axis 7.6127Å), which is a composite tungsten oxide, is 15.0% by mass, and acrylic dispersant 12.0% by mass. In addition, 73.0% by mass of toluene (second solvent) was mixed, and the mixture was pulverized and dispersed for 10 hours with a paint shaker containing 0.3 mmφ ZrO ₂ beads (hereinafter referred to as dispersion). (Abbreviated as liquid C-1).

The dispersion particle size of the tungsten oxide fine particles in dispersion C-1 was measured with a particle size distribution analyzer ELS-8000 (manufactured by Otsuka Electronics Co., Ltd.), and it was 77 nm.

Since toluene contained in the dispersion C-1 dissolves the rubber roller (nitrile butadiene rubber) of the offset printing machine, it is expected that it is difficult to apply the dispersion C-1 as it is to offset printing.

(Example 1)
As the infrared absorbing material fine particles, a dispersant having a hexagonal crystal Cs _0.33 WO ₃ which is a composite tungsten oxide similar to that in Comparative Example 1 is 23% by mass and a fatty acid is included in the structure (non-volatile content: 100%, hereinafter, dispersed) 11.5% by mass and 65.5% by mass of methyl isobutyl ketone (hereinafter abbreviated as MIBK) as a solvent were weighed.

These components were loaded into a paint shaker containing 0.3 mmφ ZrO ₂ beads, pulverized and dispersed for 10 hours, and the near-infrared fine particle dispersion (hereinafter referred to as dispersion A) according to Example 1 was obtained. Obtained.

Furthermore, 42.2 parts by weight of paulownia oil was added to 100 parts by weight of dispersion A, and the mixture was heated and distilled at 80 ° C. using a stirring type vacuum dryer (universal mixer manufactured by Tsukishima Kikai Co., Ltd.) and pressure reduction operation. Then, MIBK was removed to obtain a composite tungsten oxide fine particle dispersion (hereinafter abbreviated as Dispersion B).

Here, when the amount of residual MIBK of dispersion B was measured with a dry moisture meter, it was 1.15% by mass. The dispersed particle size of the tungsten oxide fine particles in dispersion B was measured with a particle size distribution meter (manufactured by Otsuka Electronics Co., Ltd.), and found to be 81 nm.

After the offset printing vehicle was mixed with the dispersion B according to Example 1, it was dispersed by a conventional method using a three-roll mill to produce an offset printing ink, and a printed matter was produced using the ink. The printed matter shows high transmittance in the visible light wavelength region, and the transmittance is remarkably low in the near-infrared light wavelength region. As a result, it is considered that the printed matter produced with the ink using the dispersion obtained in Example 1 can be discriminated with a near-infrared ray judging machine. That is, it has been found that by using the near-infrared fine particle dispersion according to the present invention, it is possible to easily produce an ink for offset printing having an absorption capability in the near-infrared light wavelength region and a clear contrast.

(Comparative Example 2)
As the infrared-absorbing material fine particles, 23% by mass of hexagonal Cs _0.33 WO ₃ which is a composite tungsten oxide similar to Comparative Example 1, 11.5% by mass of dispersant a, ethylene glycol having a boiling point of 197 ° C. , Abbreviated as EG) 65.5% by mass was weighed.

These components were loaded into a paint shaker containing 0.3 mmφ ZrO ₂ beads, pulverized and dispersed for 10 hours, and an infrared-absorbing fine particle dispersion (hereinafter referred to simply as “dispersion C”) according to Comparative Example 2 was obtained. A composite tungsten oxide fine particle dispersion liquid (hereinafter referred to simply as “dispersion liquid D”) according to Comparative Example 2 was obtained in the same manner as in Example 1 except that it was obtained.

Residue E of dispersion D G. It was 34.21 mass% when quantity was measured with the dry-type moisture meter. The dispersion particle diameter of the tungsten oxide fine particles in dispersion D was measured with an Otsuka Electronics particle size distribution analyzer to be 71 nm. Dispersion D contains E.I. G. Therefore, even if an ink is obtained from the dispersion D according to a general ink formulation, it is expected that the ink cannot be cured.

(Comparative Example 3)
As infrared-absorbing material fine particles, 23% by mass of hexagonal Cs _0.33 WO ₃ which is the same composite tungsten oxide as in Comparative Example 1, 11.5% by mass of dispersant a, and paulownia oil (first solvent) 65 as a solvent .5% by mass was weighed.

These components were loaded into a paint shaker containing 0.3 mmφ ZrO ₂ beads, and pulverized and dispersed for 40 hours. Since the material fine particles were added, the viscosity was high, so the grindability was poor and a near-infrared fine particle dispersion could not be obtained.

<Preparation of infrared absorbing ink>
[Examples 2 to 9]
(Preparation of infrared absorbing fine particle dispersion)
An infrared-absorbing fine particle dispersion was obtained in the same manner as in Example 1 except that the infrared-absorbing fine particle dispersion had the following composition:
Hexagonal Cs _0.33 WO ₃ : 50% by mass
Sunflower oil: 22% by mass
Dispersant a: 25% by mass
Propylene glycol monomethyl ether acetate (PGMEA): 3% by mass

(Production of oil-based offset printing ink)
According to the composition shown in Table 1, the above infrared absorbing fine particle dispersion was mixed with Best One GIGA Medium (T & KTOKA), and then dispersed by a conventional method using a three-roll mill, so that the oil-based offset printing inks of Examples 2 to 5 were used. Produced.

(Preparation of offset printing ink with oil and UV)
In accordance with the composition shown in Table 1, after mixing the above infrared-absorbing fine particle dispersion with Best One GIGA medium (T & KTOKA) and UV BF unchanged color medium (T & KTOKA), it is dispersed by a conventional method with a three-roll mill. 6-9 oil-based / UV combined offset printing inks were prepared.

[Comparative Examples 4 to 7]
Commercially available ATO (ELCOM (registered trademark) P-special product, JGC Catalysts & Chemicals Co., Ltd.) was dispersed in Best One GIGA Medium (T & KTOKA), and Comparative Examples 4 to 7 each had an ATO content of 5 mass in ink. %, 7.5% by mass, 10% by mass and 15% by mass of an ATO-containing oil-based offset printing ink was obtained.

(Infrared absorption effect of offset printing ink)
Using the offset printing inks of Examples 2 to 9 and Comparative Examples 4 to 7, respectively, printed on high-quality paper (Shiraoi high-quality paper, Nippon Paper) with a sheet-fed offset printing machine (manufactured by RYOBI) and dried to 12 Kinds of printed materials were obtained. As a result of performing offset printing using the offset printing inks of Examples 2 to 9, it was confirmed that the rubber blanket of the printing machine was not dissolved.

When eight types of printed matter obtained using the offset printing inks of Examples 2 to 9 were observed using an infrared camera (Dino-Lite Pro manufactured by ANMO), the printed surface of the offset printing ink was infrared light. The surface that was not printed with offset printing ink (for example, the base paper portion, the printing portion of general process ink, etc.) appeared white because it was transmitting or reflecting infrared rays. .

FIG. 1 shows the result of reflectance measurement for printed matter obtained using the offset printing inks of Examples 2 and 3 and the offset printing inks of Comparative Examples 4 to 7.

Contrasting reflectance at wavelengths from 352 nm to 1600 nm shown in FIG. 1, the ink prints of Examples 2 and 3 containing composite tungsten oxide are more visible than the ink prints of Comparative Examples 4 to 7 containing commercial ATO. It can be seen that the contrast between the light wavelength region and the infrared wavelength region, in particular, the contrast between the visible light wavelength region and the near infrared wavelength region is clear.

[Relationship between offset printing ink color and infrared absorption]
The following substrates and inks were prepared:
Base material: General paper (OK Prince fine quality 90 kg)
Process ink (3 colors):
Indigo (C): Super Tech GT Series Indigo (T & K TOKA Co., Ltd.)
Crimson (M): Super Tech GT Series Crimson (T & K TOKA Co., Ltd.)
Yellow (Y): Super Tech GT Series Yellow (manufactured by T & K TOKA Corporation)

According to the following print sample preparation conditions, the above three color process inks were respectively printed on the substrate to obtain three types of print samples corresponding to the respective colors:
(Print sample preparation conditions)
Printing machine: Offset printing machine RI tester (manufactured by IHI Machine System Co., Ltd.)
Ink filling amount: 0.125 cc
Ink film thickness: about 1 μm

The light reflectance of three types of printed samples was measured according to the following measurement conditions:
(Measurement condition)
Measuring device: UV-visible spectrophotometer U-4000 (manufactured by Hitachi, Ltd.)
Measurement item: Reflectance (%)
Measurement wavelength: 350-2500 nm

FIG. 2 shows the reflectance in the wavelength range of 350 to 1500 nm for the indigo (C), red (M), and yellow (Y) process inks.

The infrared absorbing ink of the present invention was used as a general color ink by combining the reflectance graph of CMY process ink shown in FIG. 2 and the reflectance graph of Examples 2 and 3 shown in FIG. The relationship between the color tone and the infrared absorptivity can be expected.

For example, in FIG. 2, the red and yellow process inks do not absorb light in the infrared wavelength region (780-1100 nm). On the other hand, in the reflectance graphs of Examples 2 and 3 shown in FIG. 1, since the average reflectance in the infrared wavelength region is lower than the average reflectance in the visible light wavelength region (380 nm to 780 nm), it is less red than visible light. It is thought that outside light is absorbed. Therefore, it can be seen that when the infrared absorbing ink of the present invention is used as a red or yellow ink, the ink can be imparted with an infrared absorbing property without affecting the red or yellow color tone.

Further, from FIG. 2, it can be considered that the indigo process ink slightly absorbs light in the infrared wavelength region (780 to 1100 nm). However, compared with the ratio in which the infrared absorbing inks of Examples 2 and 3 absorb infrared light in FIG. 1, the ratio in which the indigo process ink absorbs infrared light is so low that it does not need to be considered. Therefore, it can be seen that even when the infrared absorbing ink of the present invention is used as an indigo ink, the ink can be imparted with an infrared absorbing property without affecting the color tone of the indigo color.

Furthermore, since the infrared absorbing inks of Examples 2 and 3 do not contain a colorant, they can be grasped as special color inks or functional inks suitable for offset printing, intaglio printing, and the like. In that case, the reflectance graph of Example 2 and 3 shown by FIG. 1 can be regarded as a graph showing the light reflection characteristic of the special color ink of this invention.

Claims

General formula M x W y O z {wherein M is H, He, alkali metal element, alkaline earth metal element, 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, One or more elements selected from the group consisting of Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I, W is tungsten, O is oxygen, x, y And z are each a positive number, 0 <x / y ≦ 1 and 2.2 ≦ z / y ≦ 3.0}, or a composite tungsten oxide represented by the general formula W y O z {wherein W is tungsten, O is oxygen, and y and z are positive numbers, respectively. And one or more infrared absorbing material fine particles selected from tungsten oxide having a magnetic phase represented by 2.45 ≦ z / y ≦ 2.999; and a vehicle;
Infrared absorbing ink containing the vehicle, wherein the vehicle is a first solvent selected from vegetable oils or compounds derived from vegetable oils, alcohols, ethers, esters, ketones, aromatic hydrocarbons, aliphatic A second solvent selected from the group consisting of hydrocarbons and glycol ethers and having a boiling point of 180 ° C. or lower and a resin, and the content of the second solvent is the infrared absorbing ink. Infrared absorbing ink that is 2% by mass or less based on the mass of
The infrared absorbing ink according to claim 1, wherein the dispersed particle diameter of the infrared absorbing material fine particles is 1 nm or more and 200 nm or less.
The infrared absorbing ink according to claim 1 or 2, wherein the surface of the infrared absorbing material fine particles is coated with an oxide containing at least one selected from the group consisting of Si, Ti, Al and Zr. .
The infrared absorbing ink according to any one of claims 1 to 3, wherein the composite tungsten oxide has a hexagonal crystal structure or a hexagonal crystal structure.
The infrared absorbing ink according to any one of claims 1 to 4, wherein the first solvent is vegetable oil.
The infrared absorbing ink according to claim 5, wherein the vegetable oil is a drying oil or a semi-drying oil.
The infrared absorbing ink according to any one of claims 1 to 6, wherein the vehicle further contains a photopolymerization component.
The infrared absorbing ink according to any one of claims 1 to 7, further comprising a dispersant having a fatty acid soluble in the first solvent in its structure.
The infrared absorptivity according to any one of claims 1 to 8, wherein a content of the infrared absorbing material fine particles is 1.0% by mass or more and 45% by mass or less with respect to a mass of the infrared absorbing ink. ink.
The infrared absorbing ink according to any one of claims 1 to 9, which is used for preventing forgery.
The infrared-absorbing ink according to any one of claims 1 to 10, wherein the infrared-absorbing ink has a viscosity of 0.002 Pa · s to 200 Pa · s.
A method for obtaining a printed matter by flexographic printing, letterpress printing, offset printing, intaglio printing, gravure printing, screen printing or ink jet printing using the infrared absorbing ink according to any one of claims 1 to 11.
A printed matter comprising an anti-counterfeit printing part printed with the infrared absorbing ink according to any one of claims 1 to 11.