JP7122920B2 - Infrared absorbing UV ink and its manufacturing method - Google Patents

Description

The present invention relates to an infrared absorbing UV ink and a method for producing the same. In particular, the present invention is a tungsten-based infrared absorbing pigment that can provide printed matter with high base resistance, for example, printed matter with high wash resistance, can be easily produced, and can be printed by various printing methods. It relates to a UV ink containing and a method for producing the same.

Infrared absorbing ink can be used for various purposes, for example, it can be printed on a part of securities and used for anti-counterfeiting. US Pat. No. 6,300,002 discloses an infrared absorbing ink comprising an infrared absorbing pigment encased in a curable resin. Patent Literature 2 discloses an anti-counterfeiting infrared absorbing ink containing a tungsten-based infrared absorbing pigment.

As described in Patent Document 3, tungsten-based infrared absorbing pigments are also used as heat ray shielding materials due to their infrared absorbing properties, and are generally said to have high weather resistance.

JP 2010-174164 A WO2016/121801 JP 2016-29166 A

However, the present inventors have discovered that such a tungsten-based infrared absorbing pigment is deactivated by the influence of basic substances such as detergents, and loses its infrared absorbing ability.

On the other hand, the present inventors focused on the high weather resistance of UV ink and tried to incorporate a tungsten-based infrared absorbing pigment into the UV ink, but the pigment settled in the ink. , could not obtain ink suitable for printing.

Therefore, the present invention aims to provide a UV ink containing a tungsten-based infrared absorbing pigment, which can give prints having high base resistance, particularly high washing resistance, and which is suitable for printing, and a method for producing the same. aim.

The inventors have found that the above problems can be solved by the present invention having the following aspects.
<<Aspect 1>>
An infrared-absorbing UV ink comprising a tungsten-based infrared-absorbing pigment, a solvent, an acrylic resin soluble in the solvent, a UV-curable acrylic monomer, and a photocuring agent.
<<Aspect 2>>
The infrared absorption according to aspect 1, wherein the solvent includes a first solvent capable of dispersing the pigment and a second solvent compatible with the first solvent and capable of dissolving the acrylic resin. UV ink.
<<Aspect 3>>
An infrared absorbing UV ink according to aspect 2, wherein said first solvent and second solvent are selected from organic solvents.
<<Aspect 4>>
An infrared absorbing UV ink according to aspect 2 or 3, wherein the first solvent comprises an organic solvent of glycol ethers.
<<Aspect 5>>
An infrared absorbing UV ink according to any one of aspects 2-4, wherein said solvent further comprises a diluent solvent.
<<Aspect 6>>
With respect to a total of 100 parts by mass of the solvent, the UV-curable acrylic monomer and the photocuring agent,
The infrared absorbing UV ink according to any one of aspects 1 to 5, comprising 2 to 10 parts by mass of the tungsten-based infrared absorbing pigment and 5 to 40 parts by mass of the acrylic resin.
<<Aspect 7>>
The tungsten-based infrared absorbing pigment is
General formula (1): M _x W _y O _z {wherein M is H, He, an alkali metal element, an alkaline earth metal element, 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, one or more elements selected from the group consisting of Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I, where W is tungsten and O is oxygen; , x, y and z are each positive numbers, 0<x/y≦1, and 2.2≦z/y≦3.0}, or general Formula (2): W _y O _z {wherein W is tungsten, O is oxygen, y and z are each positive numbers, and 2.45≦z/y≦2.999 6. An infrared absorbing UV ink according to any one of aspects 1 to 6, selected from tungsten oxides having a Magneli phase represented by }.
<<Aspect 8>>
The infrared absorbing UV ink according to any one of aspects 1 to 7, which is an inkjet ink.
<<Aspect 9>>
A method for producing an infrared absorbing UV ink, including:
A pigment dispersion containing a tungsten-based infrared absorbing pigment and a first solvent capable of dispersing the pigment, and an acrylic resin composition containing an acrylic resin and a second solvent capable of dissolving the acrylic resin are mixed. to obtain a viscous dispersion, and mixing said viscous dispersion with a UV-curable acrylic monomer and a photocuring agent.
<<Aspect 10>>
10. The production method according to aspect 9, further comprising mixing a diluent solvent to adjust the viscosity.

1(a) shows the IR reflection spectrum of Example 4, and FIG. 1(b) shows the IR reflection spectrum of Comparative Example 1. FIG.

《Infrared absorbing UV ink》
The infrared-absorbing UV ink of the present invention contains a tungsten-based infrared-absorbing pigment, a solvent, a solvent-soluble acrylic resin, a UV-curable acrylic monomer, and a photocuring agent.

UV inks usually do not contain a solvent because the viscosity of the UV-curable acrylic monomer is sufficiently low. .

As a result of investigations by the present inventors, even if an attempt is made to disperse a tungsten-based infrared absorbing pigment in the UV ink having the conventional structure, the pigment immediately settles in the ink, or a dispersion containing the pigment separated from the UV ink, and the dispersion was not practical as a printing ink.

On the other hand, the present inventors have further studied and found that a printing ink can be obtained by first dispersing a tungsten-based infrared absorbing pigment in an acrylic resin composition and mixing it with a UV ink having a conventional structure. It was found that a practical dispersion can be obtained as It was also found that printed matter printed with this ink has very high base resistance, that is, washing resistance. Since printed matter may be washed together with clothes, the ink of the present invention that can provide printed matter with high base resistance is very useful.

Without being bound by theory, the effect of the ink of the present invention as described above is due to the fact that the ink of the present invention contains an acrylic resin that is soluble in a solvent. It is believed that this is due to the fact that a coating can be formed and that the acrylic resin has a high affinity with UV-curable acrylic monomers.

In addition, it was found that the infrared absorption of the tungsten-based infrared absorbing pigment decreases when it is not used as it is highly dispersed, but the printed matter printed with the UV ink of the present invention has high infrared absorption. Furthermore, conventional UV inks have been found to be advantageous in that they are solvent-free, but in the UV inks of the present invention, at least for certain embodiments, the solvent is incorporated into the UV-cured acrylic resin after printing. Therefore, it was possible to omit the process of drying the solvent and the like.

Further, the ink of the present invention can be manufactured without obtaining particularly complicated processes and can be printed by various printing methods. In particular, the ink of the present invention is ink jet printable as a result of the high degree of dispersion of the tungsten-based infrared absorbing pigment. Infrared-absorbing inks capable of inkjet printing have not been put into practical use in the past, and the UV ink of the present invention is particularly advantageous in making it possible.

The viscosity of the ink of the present invention at a temperature of about 25° C. is preferably about 300 mPa·s or less, about 150 mPa·s or less, or about 80 mPa·s or less, and the viscosity is about 10 mPa·s or more. , or about 15 mPa·s or more.

<Tungsten infrared absorbing pigment>
In the ink of the present invention, a tungsten-based infrared absorbing pigment is dispersed. For example, as such a tungsten-based infrared absorbing pigment, the pigment disclosed in Patent Document 2 can be mentioned.

Therefore, as a tungsten-based infrared absorbing pigment, the general formula (1): M _x W _y O _z {wherein M is H, He, an alkali metal element, an alkaline earth metal element, 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 one or more elements selected from the group consisting of I, W is tungsten, O is oxygen, x, y and z are each positive numbers, 0<x/y≦1, and 2.2≦z/y≦3.0} or the general formula (2): W _y O _z {wherein W is tungsten, O is oxygen, y and z are positive numbers; 45≦z/y≦2.999} can be mentioned.

As a method for producing a tungsten-based infrared absorbing pigment, a method for producing a composite tungsten oxide or a tungsten oxide having a Magneli phase described in JP-A-2005-187323 can be used.

The element M is added to the composite tungsten oxide represented by the general formula (1). For this reason, including the case of z/y = 3.0 in general formula (1), free electrons are generated, and absorption characteristics derived from free electrons appear in the near-infrared light wavelength region. 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, the M element is one of Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe and Sn. There can be more than one type.

By treating the composite tungsten oxide represented by the general formula (1) with a silane coupling agent, near-infrared absorption and transparency in the visible light wavelength region may be enhanced.

If the value of x/y, which indicates the amount of the element M to be added, is greater than 0, a sufficient amount of free electrons are generated and a sufficient near-infrared absorbing effect can be obtained. As the amount of the element M added increases, the amount of free electrons supplied increases and the near-infrared absorption effect also increases. The value of x/y may be 1 or less to prevent the formation of an impurity phase in the pigment-containing layer. The value of x/y may be 0.001 or more, 0.2 or more, or 0.30 or more, and may be 0.85 or less, 0.5 or less, or 0.35 or less. The value of x/y can in particular be 0.33.

In the general formulas (1) and (2), the value of z/y indicates the level of oxygen content control. The composite tungsten oxide represented by the general formula (1) has a z/y value that satisfies the relationship of 2.2 ≤ z/y ≤ 3.0, so the tungsten oxide represented by the general formula (2) In addition to the same oxygen control mechanism as at work, there is a supply of free electrons due to the addition of element M even when z/y=3.0. In general formula (1), the value of z/y may satisfy the relationship of 2.45≤z/y≤3.0.

When the composite tungsten oxide represented by the general formula (1) has a hexagonal crystal structure or consists of a hexagonal crystal structure, the infrared-absorbing material fine particles transmit more light in the visible light wavelength region, In addition, the absorption in the near-infrared light wavelength region is increased. When positive ions of the element M are added to the voids of the hexagonal crystal, the transmission in the visible light wavelength region increases and the absorption in the near-infrared light wavelength region increases. Here, in general, hexagonal crystals are formed when an element M having a large ionic radius is added. Specifically, when an element having a large ionic radius such as Cs, K, Rb, Tl, In, Ba, Sn, Li, Ca, Sr, and Fe is added, hexagonal crystals are likely to be formed. However, the present invention is not limited to these elements, and elements other than these elements may be used as long as the additional element M is present in the hexagonal voids formed by ₆ units of WO.

When the composite tungsten oxide having a hexagonal crystal structure has a uniform crystal structure, the addition amount of the additive element M can be 0.2 or more and 0.5 or less as a value of x/y, It can be 0.30 or more and 0.35 or less, and particularly 0.33. It is considered that the additive element M is arranged in substantially all of the hexagonal voids when the value of x/y is 0.33.

In addition to the hexagonal crystal, tetragonal or cubic tungsten bronze also has a near-infrared absorption effect. Depending on these crystal structures, the absorption position in the near-infrared light wavelength region tends to change, and the absorption position tends to move to the longer wavelength side in the order of cubic < tetragonal < hexagonal. In addition, the absorption in the visible light wavelength region is small in the order of hexagonal < tetragonal < cubic. For this reason, hexagonal tungsten bronze may be used 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 Magneli phase represented by the general formula (2), the so-called "Magneli phase" having a composition ratio satisfying the relationship of 2.45 ≤ z/y ≤ 2.999 in which the value of z/y is Because of its high stability and high absorption characteristics in the near-infrared wavelength region, it is suitably used as a near-infrared absorbing pigment.

Since the pigments described above largely absorb light in the near-infrared wavelength region, particularly light in the vicinity of a wavelength of 1000 nm, many of the pigments have a transmitted color tone of bluish to greenish. Further, the dispersed particle size of the tungsten-based infrared absorbing pigment can be selected depending on the purpose of use. First, in the case of application while maintaining transparency, it is preferable to have a dispersed particle size of 2000 nm or less in terms of volume average. This is because when the dispersed particle diameter is 2000 nm or less, the difference between the peak of transmittance (reflectance) in the visible light wavelength region and the bottom of the absorption in the near-infrared light wavelength region increases. This is because the effect as a near-infrared absorbing pigment having transparency can be exhibited. Furthermore, particles with a dispersed particle size smaller than 2000 nm do not completely block light due to scattering, and can maintain visibility in the visible light wavelength region and at the same time efficiently maintain transparency.

Furthermore, when emphasizing transparency in the visible light wavelength region, it is preferable to consider scattering due to particles. Specifically, the volume average dispersed particle size of the tungsten-based infrared absorbing pigment is preferably 200 nm or less, more preferably 100 nm or less, 50 nm or less, or 30 nm or less. When the dispersed particle diameter of the infrared-absorbing material fine particles is 200 nm or less, geometric scattering or Mie scattering is reduced, resulting in a Rayleigh scattering region. In the Rayleigh scattering region, the scattered light is reduced in inverse proportion to the sixth power of the diameter of the dispersed particles. Therefore, as the diameter of the dispersed particles is reduced, the scattering is reduced and the transparency is improved. Furthermore, when the dispersed particle size is 100 nm or less, the scattered light is extremely small, which is preferable. From the viewpoint of avoiding light scattering, the smaller the dispersed particle size, the better. On the other hand, when the dispersed particle size is 1 nm or more, 3 nm or more, 5 nm or more, or 10 nm or more, industrial production tends to be easy. Here, the volume-average dispersed particle diameter of the tungsten-based infrared absorbing pigment is obtained by irradiating the fine particles in Brownian motion with a laser beam and obtaining the particle diameter from the light scattering information obtained therefrom. It was measured using a particle size distribution meter (manufactured by Nikkiso Co., Ltd.).

The content of the tungsten-based infrared absorbing pigment in the ink of the present invention is 0.1% by weight or more, 0.5% by weight or more, 1.0% by weight or more, 2.0% by weight or more, or 3.0% by weight. % or more, 20 wt% or less, 10 wt% or less, 8.0 wt% or less, 5.0 wt% or less, 3.0 wt% or less, or 1.0 wt% or less good.

The ink of the present invention may contain 3 parts by mass or more, 5 parts by mass or more, 8 parts by mass or more, or 10 parts by mass or more of a tungsten-based infrared absorbing pigment with respect to 100 parts by mass of the solvent. It may be included in parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, 15 parts by mass or less, or 10 parts by mass or less.

In the ink of the present invention, 1 part by mass or more, 2 parts by mass or more, and 3 parts by mass of a tungsten-based infrared absorbing pigment is added to a total of 100 parts by mass of a solvent, a UV-curable acrylic monomer, and a photocuring agent. 20 parts by mass or less, 15 parts by mass or less, 10 parts by mass or less, 8 parts by mass or less, 5 parts by mass or less, or 4 parts by mass or less.

<Acrylic resin>
If the acrylic resin used in the ink of the present invention is soluble in solvents, has a high affinity with UV-curable acrylic monomers, and can be used without separation in the ink, The type is not particularly limited.

Examples of acrylic resins include polymers and copolymers of acrylic acid and its esters, acrylamide, acrylonitrile, methacrylic acid and its esters. can be used.

The glass transition temperature (Tg) of the acrylic resin is not particularly limited. °C or lower.

The content of the acrylic resin in the ink of the present invention may be 1.0% by weight or more, 3.0% by weight or more, 5.0% by weight or more, 10% by weight or more, or 15% by weight or more. , 40% by weight or less, 30% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, or 8.0% by weight or less.

The ink of the present invention may contain 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, 20 parts by mass or more, or 30 parts by mass or more of an acrylic resin with respect to 100 parts by mass of the solvent. , 100 parts by mass or less, 80 parts by mass or less, 60 parts by mass or less, 50 parts by mass or less, 40 parts by mass or less, or 30 parts by mass or less.

The ink of the present invention contains 3 parts by mass or more, 5 parts by mass or more, or 8 parts by mass or more of an acrylic resin with respect to a total of 100 parts by mass of a solvent, a UV-curable acrylic monomer and a photocuring agent. It may be contained in an amount of 10 parts by mass or more, and may be contained in an amount of 50 parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, or 15 parts by mass or less.

<solvent>
The UV ink of the present invention contains a solvent. Conventional UV inks usually do not contain a solvent, and it was considered advantageous in terms of workability that they do not contain this solvent. After printing, it was possible to omit processes such as drying of the solvent because the solvent was incorporated into the UV-cured acrylic resin.

The solvent used in the present invention is not particularly limited as long as it can dissolve the acrylic resin and the advantageous effects of the present invention can be obtained. For example, solvents used in the present invention include alcohols such as ethanol, propanol, butanol, isopropyl alcohol, isobutyl alcohol and diacetone alcohol, ethers such as methyl ether, ethyl ether and propyl ether, esters such as ethyl acetate, Ketones such as acetone, methyl ethyl ketone, diethyl ketone, cyclohexanone, ethyl isobutyl ketone, and methyl isobutyl ketone, aromatic hydrocarbons such as toluene, xylene, and benzene, aliphatic hydrocarbons such as normal hexane, heptane, and cyclohexane, and propylene glycol. Various organic solvents such as glycol ethers such as monomethyl ether acetate and propylene glycol monoethyl ether can be used.

In the present invention, it is preferable to use a combination of multiple types of solvents. In particular, the solvent used in the present invention includes a first solvent capable of dispersing the tungsten-based infrared absorbing pigment and a second solvent compatible with the first solvent and capable of dissolving the acrylic resin. Preferably, they are used in combination at least. In this case, the ink of the present invention is comparatively Easy to prepare.

In this case, the first solvent, the second solvent and the solvent for dilution may all be the same type of solvent, the two may be the same type, or they may be different types of solvents. Well, any of the types of solvents described above can be used. In this case, the first solvent can particularly include an organic solvent of glycol ethers, and the second solvent can particularly include an aromatic hydrocarbon or an aliphatic hydrocarbon solvent, As solvents for dilution, mention may be made in particular of solvents of ethers, esters, ketones, aromatic hydrocarbons or aliphatic hydrocarbons.

The solvent content in the ink of the present invention may be 10% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, or 40% by weight or more. % or less, 55 wt% or less, 50 wt% or less, 45 wt% or less, 40 wt% or less, or 35 wt% or less.

The ink of the present invention contains 10 parts by mass or more, 20 parts by mass or more, 30 parts by mass or more, and 40 parts by mass of the solvent with respect to a total of 100 parts by mass of the solvent, the UV-curable acrylic monomer and the photocuring agent. Above, 45 parts by mass or more, or 50 parts by mass or more, may be included, and may be included in 80 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, 50 parts by mass or less, or 45 parts by mass or less.

<UV curable acrylic monomer>
Acrylic monomers conventionally used in UV inks can be used as UV-curable acrylic monomers. As used herein, acrylic monomers include not only monomers but also oligomers as long as they are liquid at room temperature.

Examples of such acrylic monomers include acrylates having an ethylenically unsaturated bond, and monofunctional acrylates and/or bifunctional acrylates may be used.

Examples of monofunctional acrylates include caprolactone acrylate, isodecyl acrylate, isooctyl acrylate, isomyristyl acrylate, isostearyl acrylate, 2-ethylhexyl-diglycol diacrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl hexahydro phthalic acid, neopentyl glycol acrylic acid benzoate, isoamyl acrylate, lauryl acrylate, stearyl acrylate, butoxyethyl acrylate, ethoxy-diethylene glycol acrylate, methoxy-triethylene glycol acrylate, methoxy-polyethylene glycol acrylate, methoxydipropylene glycol acrylate, phenoxyethyl acrylate, phenoxy-polyethylene glycol acrylate, nonylphenol ethylene oxide adduct acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2- acryloyloxyethyl-succinic acid, 2-acryloyloxyethyl-phthalic acid, 2-acryloyloxyethyl-2-hydroxyethyl-phthalic acid and the like.

Bifunctional acrylates include, for example, hydroxypivalic acid neopentyl glycol diacrylate, alkoxylated hexanediol diacrylate, polytetramethylene glycol diacrylate, trimethylolpropane acrylic acid benzoate, diethylene glycol diacrylate, triethylene glycol diacrylate, Tetraethylene glycol diacrylate, polyethylene glycol (200) diacrylate, polyethylene glycol (400) diacrylate, polyethylene glycol (600) diacrylate, neopentyl glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butane diol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, dimethylol-tricyclodecane diacrylate, bisphenol A diacrylate and the like.

Furthermore, it is preferable to use oligomers such as urethane acrylate, polyester acrylate, epoxy acrylate, silicone acrylate, and polybutadiene acrylate, for example.

The content of the UV-curable acrylic monomer in the ink of the present invention is 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, 45% by weight or more, or 50% by weight or more. 60% by weight or less, 55% by weight or less, 50% by weight or less, 45% by weight or less, 40% by weight or less, or 35% by weight or less.

The ink of the present invention contains 10 parts by mass or more, 20 parts by mass or more, 30 80 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, 50 parts by mass or less, or 45 parts by mass or less may be included in

<Photo-curing agent>
The photo-curing agent is a compound that generates radicals such as active oxygen when irradiated with ultraviolet rays, and photo-curing agents conventionally used for UV inks can be used. The type of the photo-curing agent used in the present invention is not particularly limited as long as it can photopolymerize the UV-curable acrylic monomer.

Examples of photopolymerization initiators include, but are not limited to, acetophenone, α-aminoacetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, 2-hydroxy-2-methyl-1-phenylpropane. -1-one, benzyl dimethyl 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)propane-1- Acetophenones such as one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone; bazoin, bazoin methyl ether, benzoin ethyl ether, benzoin-n-propyl ether, bazoin isopropyl ether , benzoin-n-butyl ether, benzoin isobutyl ether, benzoin dimethyl ketal, benzoin peroxide; acylphophine oxides such as 2,4,6-trimethoxybenzoin diphenylphosphine oxide; benzyl and methylphenyl-glyoxy ester; benzophenone, methyl-4-phenylbenzophenone, o-benzoylbenzoate, 2-chlorobenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenylsulfide, acryl-benzophenone, 3, Benzophenones such as 3′4,4′-tetra(t-butylperoxycarbonyl)benzophenone and 3,3′-dimethyl-4-methoxybenzophenone; 2-methylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, Thioxanthones such as 2,4-diethylthioxanthone, 2-chlorothioxanthone and 2,4-dichlorothioxanthone; Aminobenzophenones such as Michler's ketone and 4,4'-diethylaminobenzophenone; Tetramethylthiuram monosulfide; Azobisisobutyronitrile di-tert-butyl peroxide; 10-butyl-2-chloroacridone; 2-ethylanthraquinone; 9,10-phenanthrenequinone; camphor quinones; titanocenes, combinations thereof, and the like.

A photopolymerization initiation aid such as ethyl 4-dimethylaminobenzoate and isoamyl 4-dimethylaminobenzoate may be used in combination with the photopolymerization initiator.

The amount of the photocuring agent used relative to 100 parts by weight of the UV-curable acrylic monomer is 0.1 parts by weight or more, 0.5 parts by weight or more, 1.0 parts by weight or more, 2.0 parts by weight or more, or 3 parts by weight. 0 parts by weight or more, 20 parts by weight or less, 10 parts by weight or less, 8.0 parts by weight or less, 5.0 parts by weight or less, 3.0 parts by weight or less, or 1.0 parts by weight or less There may be.

<Other - Dispersant>
In order to enhance the dispersibility of the tungsten infrared absorbing pigment in the ink, the ink may contain a dispersant. Examples of dispersants include compounds having functional groups such as amines, hydroxyl groups, carboxyl groups, and epoxy groups. These functional groups are adsorbed on the surface of the tungsten-based infrared absorbing pigment and prevent aggregation of the tungsten-based infrared absorbing pigment, thereby uniformly dispersing the tungsten-based infrared absorbing pigment in the ink.

Dispersants that can be suitably used include phosphate ester compounds, polymeric dispersants, silane coupling agents, titanate coupling agents, aluminum coupling agents, etc., but are limited to these. is not. Examples of polymeric dispersants include acrylic polymeric dispersants, urethane polymeric dispersants, acrylic/block copolymer polymeric dispersants, polyether dispersants, and polyester polymeric dispersants. . Among them, it is preferable that the dispersant is powder because it is easily kneaded with the thermoplastic resin.

The content of the dispersant in the ink may be 0.5% by weight or more, 1.0% by weight or more, 1.5% by weight or more, or 2.0% by weight or more, and 5.0% by weight or less. , 3.0 wt % or less, 2.0 wt % or less, or 1.5 wt % or less.

The ink of the present invention contains 0.5 parts by mass or more, 1.0 parts by mass or more, and 1.5 parts by mass of a dispersant with respect to a total of 100 parts by mass of a solvent, a UV-curable acrylic monomer and a photocuring agent. 10 parts by mass or less, 8.0 parts by mass or less, 5.0 parts by mass or less, 3.0 parts by mass or less, or 2.0 parts by mass or less may be included in

The weight of the dispersant relative to the weight of the tungsten infrared absorbing pigment (weight of dispersant/weight of tungsten infrared absorbing pigment) is 1.0 or more, 2.0 or more, 3.0 or more, or 4.0 or more. 10 or less, 8.0 or less, 5.0 or less, 4.0 or less, 3.0 or less, 2.0 or less, or 1.0 or less.

<<Manufacturing method of infrared absorbing UV ink>>
In the method for producing an infrared absorbing UV ink of the present invention, a pigment dispersion containing a tungsten infrared absorbing pigment and a first solvent is mixed with an acrylic resin composition containing an acrylic resin and a second solvent. and mixing the viscous dispersion with a UV curable acrylic monomer and a photocuring agent.

In addition, the method of the present invention may further comprise mixing a diluent solvent to adjust the viscosity. In this case, the solvent for dilution may be mixed with the pigment dispersion and/or the acrylic resin composition before obtaining the viscous dispersion, or may be mixed with the viscous dispersion after obtaining the viscous dispersion. , may be mixed with the UV-curable acrylic monomer.

The infrared-absorbing UV ink obtained by the method of the present invention may be the infrared-absorbing UV ink described above. can be referred to.

The present invention will be described in more detail with the following examples, but the invention is not limited thereto.

《Manufacturing example》
Using 10 grams of ethyl acetate as a diluent solvent, 7.5 grams of an acrylic resin composition containing an acrylic resin and its solvent (DIC Corporation, Acrydic (trademark) A-814) was diluted. To this diluted product, 10 grams of a pigment dispersion (Sumitomo Metal Mining Co., Ltd., CWO (trademark) YMS-01A2) in which a tungsten-based infrared absorbing pigment is dispersed in a solvent was added and mixed. To the mixture, 30 grams of a UV curable composition containing a UV curable acrylic monomer and a photocuring agent was added and mixed to obtain the ink of Example 1.

Here, the above acrylic resin composition (DIC Corporation, Acrydic (trademark) A-814) contains 50% by weight of acrylic resin (Tg: 85° C.), 42.5% by weight of toluene, and 7.5% by weight of toluene. It contained 5% by weight of ethyl acetate.

The above pigment dispersion (Sumitomo Metal Mining Co., Ltd., CWO (trademark) YMS-01A2) contains 25% by weight of hexagonal Cs _0.33 WO ₃ , which is a tungsten-based infrared absorbing pigment, and 58.9% by weight of Propylene glycol monomethyl ether acetate, 1.86 wt% dipropylene glycol monomethyl ether, 1.74 wt% butyl acetate and 12.5 wt% dispersant.

The UV curable composition was prepared by mixing 100 parts by weight of a UV curable acrylic monomer (BESTCURE, T&K TOKA Co., Ltd.) with 4 parts by weight of a photocuring agent (IRGACURE500, BASF).

The inks of Examples 2-5 were obtained by varying the weight ratios as described in Table 1.

Inks of Examples 6 and 7 were obtained in the same manner as in Example 4, except that the acrylic resin compositions were changed to Acrydic VU-191 and Acrydic WFL-523, respectively. Here, Acrydic VU-191 contains 55% by weight acrylic resin (Tg: 95° C.), 22.5% by weight toluene, and 22.5% by weight isobutyl acetate; Acrydic WFL-523 contained 50 wt% acrylic resin (Tg: 85°C), 35 wt% butyl acetate, and 15 wt% butanol.

Also, an ink of Comparative Example 1 was obtained without using the acrylic resin composition and the UV curable composition.

As Comparative Example 2, an attempt was made to produce an ink without using the acrylic resin composition and the solvent for dilution described above, but the tungsten-based infrared absorbing pigment precipitated, resulting in a failure to obtain a printable ink. I couldn't.

Moreover, as Comparative Example 3, an attempt was made to produce an ink without using only the above acrylic resin composition, but similarly to Comparative Example 2, a printable ink could not be obtained.

"evaluation"
<viscosity>
The viscosities of the inks of Examples 1 to 7 and Comparative Example 1 above were measured in accordance with JIS Z 8803 using a tuning fork vibration viscometer SV-1A (natural frequency of 30 Hz) manufactured by A&D Co., Ltd. and a 2 ml sample was measured at a temperature of 25°C.

<Infrared reflectance before and after washing>
The inks of Examples 1 to 7 and Comparative Example 1 were applied to OCR paper using a #10 wire bar. The coated article was made into a size of 2 cm x 4 cm and immersed in an aqueous solution having a pH of 12 and a temperature of 90°C for 30 minutes. This aqueous solution was prepared by adding 0.5% by weight laundry detergent (Attack™, Kao Corporation) and 1% by weight sodium carbonate to distilled water. After the immersion, it was washed with water and dried, and the infrared reflectance was measured for each example using a UV-vis reflection spectrometer in accordance with JIS K 0115. Then, the reflectance at a wavelength of 1000 nm was compared before and after this washing test. It should be noted that the lower the numerical value of the infrared reflectance, the higher the infrared absorption.

<Pigment retention rate before and after washing>
For the above coated article, the reflectance at a wavelength of 1000 nm before the washing test is calculated with respect to the reflectance at a wavelength of 1000 nm after the washing test. It was used as an index to judge whether it could be maintained.

<Results of observation with an infrared camera after washing>
The coated article after the washing test was observed with an infrared camera. This camera used an infrared LED with a wavelength of 940 nm for infrared illumination, and had a filter for cutting light with a wavelength of 820 nm or less. Observation was made under the following observation conditions: 250,000 pixels, horizontal 67° and vertical 47° lens angle of view, and 22×18 mm drawing area, and judged as follows:
○: The coated part can be clearly distinguished;
△: The coated part can be distinguished by checking the uncoated part and the coated part at the same time;
×: The coated portion cannot be distinguished even if the non-coated portion and the coated portion are checked at the same time.

"result"
The results are summarized in Table 1. In addition, infrared reflection spectra of Example 4 and Comparative Example 1 are shown in FIG.

Referring to Examples 1 to 5, it can be seen that the higher the amount of the acrylic resin composition, the higher the pigment residual rate. This is because the acrylic resin has a higher affinity with the UV-curable acrylic monomer by coating the tungsten-based infrared absorbing pigment, and the alkali resistance is developed by the coating. Conceivable. By referring to Examples 6 and 7, it can be seen that similar effects can be obtained even if the type of acrylic resin composition is changed.

In Comparative Example 1, the infrared absorbing function was lost in the washing test due to the low alkali resistance of the tungsten-based infrared absorbing pigment.

Claims (10)

Including a tungsten-based infrared absorbing pigment, a solvent, an acrylic resin soluble in the solvent, a UV-curable acrylic monomer, and a photocuring agent,
The solvent comprises a first solvent capable of dispersing the pigment, and a second solvent compatible with the first solvent and capable of dissolving the acrylic resin,
The first solvent contains an organic solvent of glycol ethers,
wherein the second solvent comprises a solvent selected from aromatic hydrocarbons and aliphatic hydrocarbons;
Infrared absorbing UV ink. An infrared absorbing UV ink according to claim 1 , wherein said solvent further comprises a diluent solvent. 3. An infrared absorbing UV ink according to claim 2, wherein said diluent solvent comprises a solvent selected from ethers, esters, ketones, aromatic hydrocarbons and aliphatic hydrocarbons. An infrared absorbing UV ink according to any one of claims 1-3, further comprising a dispersing agent. 5. An infrared absorbing UV ink according to claim 4, wherein said dispersant is a compound having a functional group selected from amine, hydroxyl group, carboxyl group and epoxy group. With respect to a total of 100 parts by mass of the solvent, the UV-curable acrylic monomer and the photocuring agent,
The infrared absorbing UV ink according to any one of claims 1 to 5, comprising 2 to 10 parts by mass of the tungsten infrared absorbing pigment and 5 to 40 parts by mass of the acrylic resin. The tungsten-based infrared absorbing pigment is
General formula (1): M _x W _y O _z {wherein M is H, He, an alkali metal element, an alkaline earth metal element, 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, one or more elements selected from the group consisting of Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I, where W is tungsten and O is oxygen; , x, y and z are each positive numbers, 0<x/y≦1, and 2.2≦z/y≦3.0}, or general Formula (2): W _y O _z {wherein W is tungsten, O is oxygen, y and z are each positive numbers, and 2.45≦z/y≦2.999 }, the infrared absorbing UV ink according to any one of claims 1 to 6, which is selected from tungsten oxides having a Magneli phase represented by }. 8. The infrared absorbing UV ink according to any one of claims 1 to 7, which is an inkjet ink. A method for producing an infrared absorbing UV ink, including:
A dispersion containing a tungsten-based infrared absorbing pigment and a first solvent capable of dispersing the pigment, and an acrylic resin composition containing an acrylic resin and a second solvent capable of dissolving the acrylic resin are mixed. to obtain a viscous dispersion,
here,
The first solvent contains an organic solvent of glycol ethers,
The second solvent comprises a solvent selected from aromatic hydrocarbons and aliphatic hydrocarbons, and
Mixing the viscous dispersion with a UV curable acrylic monomer and a photocuring agent. 10. The production method according to claim 9, further comprising mixing a diluent solvent to adjust the viscosity.

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