WO2019188851A1 - Black type ink composition for ink-jet printing, light-shielding film, optical member, and method for forming image - Google Patents

Abstract

An embodiment of the present invention is a black type ink composition for ink-jet printing which comprises carbon black particles, titanium dioxide particles, and a basic dispersant, wherein the content of the titanium dioxide particles is 15-45 mass% with respect to the whole mass of the composition and the mass ratio of the content of the titanium dioxide particles to the content of the carbon black particles is 2.0-15.0. Also provided are a light-shielding film, an optical member, and a method for forming an image.

Description

Black ink composition for inkjet, light-shielding film, optical member, and image forming method

The present disclosure relates to a black ink composition for inkjet, a light shielding film, an optical member, and an image forming method.

The light-shielding film or member is used in various fields, and is used not only for the purpose of shielding light, but also for the purpose of absorbing light and the application of a decoration function. Yes.

The light-shielding film is also used for optical applications, for example.
A lens is known as an example of an optical application, and the lens is provided with a light-shielding film on the side surface of the lens, that is, on the outer peripheral surface of the lens when viewed from the incident direction of light. By attaching a light shielding film to the outer peripheral surface of the lens, the difference in refractive index at the interface between the lens and the light shielding film becomes smaller than the interface between the lens and the air. It is possible to reduce the internal reflection that occurs when hitting. This makes it possible to suppress optical failures such as flare or ghost that are likely to occur in an image.

In recent years, high refractive index glass having a refractive index of 1.8 or more has been developed and used as an optical glass. When this optical glass is used for a lens, for example, the difference in refractive index between the light shielding film and the light-shielding film becomes wider than before, and as a result, even if the lens has a high refractive index, a high refractive lens. It is inferred that the performance of the is not fully demonstrated.

As a technique related to the above, an optical that contains at least a resin and a colorant, and has an average extinction coefficient of 0.03 to 0.15 that is an average value of extinction coefficients from a wavelength of 400 nm to a wavelength of 700 nm of the entire light shielding film A light-shielding film for an element is disclosed (for example, see JP 2011-186437 A).

As described above, when an optical failure is to be suppressed by attaching a light shielding film to a lens which is an example of an optical member, it is important to reduce the refractive index difference between the lens and the light shielding film. However, when an optical glass having a refractive index of 1.8 or more is used, it is necessary to increase the refractive index of the light shielding film in order to keep the refractive index difference from the lens small.

In the above-mentioned Japanese Patent Application Laid-Open No. 2011-186437, a black component is realized by adding a black pigment as a main component if necessary, and further containing non-black particles within a range not exceeding the amount of black pigment as necessary. Examples have been disclosed.
With such a composition, it is presumed that internal reflection at the interface between the lens and the light-shielding film has not been suppressed since the effect of improving the refractive index cannot be expected despite the high absorption of the light-shielding film. Further, since the light shielding film described in JP2011-186437A is a film formed by a reactive epoxy paint, this paint is simply applied to a film forming method using an ink jet method. It is difficult to form a film.

The present disclosure has been made in view of the above.
A problem to be solved by an embodiment of the present invention is to provide a black ink composition for inkjet that has a black color tone and has a film having a high refractive index (preferably 1.75 or more). It is in.
A problem to be solved by another embodiment of the present invention is to provide a light-shielding film, an optical member, and an image forming method having a black color tone and a high refractive index (preferably 1.75 or more). .

Specific means for solving the problems include the following aspects.
<1> containing carbon black particles, titanium dioxide particles, and a basic dispersant,
The content of titanium dioxide particles is 15% by mass or more and 45% by mass or less with respect to the total mass of the composition, and the mass ratio of the content of titanium dioxide particles to the content of carbon black particles is 2.0 or more and 15%. This is a black ink composition for inkjet which is 0.0 or less.
<2> The basic dispersant is the black ink composition for inkjet according to <1>, wherein the amine value is 10 mgKOH / g or more and 80 mgKOH / g or less.
<3> The titanium dioxide particles are the black ink composition for inkjet according to <1> or <2>, wherein the average primary particle diameter is 10 nm or more and 100 nm or less.
<4> The black ink composition for inkjet according to any one of <1> to <3>, wherein the content of the carbon black particles is 1% by mass to 6% by mass with respect to the total mass of the composition It is a thing.
<5> The black ink composition for inkjet according to any one of <1> to <4>, further comprising an organic solvent having a boiling point of 120 ° C. or higher.
<6> The black ink composition for inkjet according to <5>, wherein the content of the organic solvent is 10% by mass to 55% by mass with respect to the total mass of the composition.
<7> Contains at least two organic solvents having a boiling point of 120 ° C. or higher, and among organic solvents having a boiling point of 120 ° C. or higher, the boiling point of one organic solvent is BPa, and the boiling point of the other organic solvent is BPb In this case, the surface tension of one kind of organic solvent satisfying the relationship of 120 ° C. <BPa <BPb <250 ° C. and having a boiling point of 120 ° C. or higher is γa, and the others The black ink composition for inkjet according to <5> or <6>, satisfying a relationship of γa <γb, where γb is a surface tension of an organic solvent having mN / m as a unit. .
<8> γa and γb are the black ink compositions for inkjet according to <7>, which satisfy a relationship represented by γa <30 mN / m <γb.
<9> The black ink composition for inkjet according to any one of <1> to <8>, further comprising at least one curable compound selected from a photocurable monomer and a photocurable resin. .

<10> A light-shielding film that is a cured product of the black ink composition for inkjet according to any one of <1> to <9>.
<11> The light shielding film according to <10>, wherein the refractive index is 1.75 or more.
<12> The light shielding film according to <10> or <11>, wherein the content of the dye is less than 10% by mass.
<13> The light-shielding film according to any one of <10> to <12> used for an optical member.
<14> An optical member comprising a base material and the light-shielding film according to any one of <10> to <13>.
<15> The optical member according to <14>, wherein the substrate is a glass substrate or a resin substrate, and has a light-shielding film on an outer peripheral surface when the thickness direction of the glass substrate or the resin substrate is used as an axis.
<16> An image forming method including a step of applying a black ink composition for ink jet according to any one of <1> to <9> on a base material by an ink jet method.

According to one embodiment of the present invention, there is provided a black ink composition for inkjet which has a black color tone and has a film having a high refractive index (preferably 1.75 or more).
According to another embodiment of the present invention, a light-shielding film, an optical member, and an image forming method having a black color tone and a high refractive index (preferably 1.75 or more) are provided.

Hereinafter, the black ink composition for inkjet, the light shielding film, the optical member, and the image forming method will be described in detail.

In this specification, “black” or “black” means that the optical density (OD) per 1 μm thickness is 0.1 or more (OD ≧ 0.1 / μm), and the absorbance at 580 nm with respect to the absorbance at 480 nm. The ratio is 0.3 to 3.

In this specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. In a numerical range described in stages in the present disclosure, an upper limit value or a lower limit value described in a numerical range may be replaced with an upper limit value or a lower limit value in another numerical range. Further, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the values shown in the examples.

In the present specification, the amount of each component in the composition is the sum of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. Means quantity.

In this specification, “mass%” and “weight%” are synonymous, and “mass part” and “weight part” are synonymous. Moreover, in this specification, the combination of two or more preferable aspects is a more preferable aspect.

<Black ink composition for inkjet>
The black ink composition for inkjet of the present disclosure (hereinafter, also simply referred to as “black ink of the present disclosure” or “black ink”) includes carbon black particles, titanium dioxide particles, a basic dispersant, The content of titanium dioxide particles is 15% by mass or more and 45% by mass or less with respect to the total mass of the composition, and the mass ratio of the content of titanium dioxide particles to the content of carbon black particles is 2. 0 or more and 15.0 or less.

The light-shielding film has been used in various applications, for example, for optical applications. A lens known as an example of an optical application is provided with a light shielding film on a side surface of the lens, that is, an outer peripheral surface when the incident direction of light is taken as an axis, thereby suppressing internal reflection of light in the lens. In order to suppress this internal reflection, it is important that the refractive index of the lens is close to the refractive index of the light shielding film and that the light shielding film itself hardly reflects light.
On the other hand, in recent years, a glass having a high refractive index of 1.8 or more has been developed as an optical glass. When this optical glass is used for a lens, for example, it is presumed that the performance as a high refractive lens cannot be sufficiently exhibited as a result of the difference in refractive index from the light shielding film spreading.
Among conventional techniques, the light shielding film described in JP2011-186437A is considered good in terms of light absorption of the light shielding film itself, but suppresses internal reflection at the interface between the lens and the light shielding film. It is inferred that there is room for improvement in the effect. In addition, since the technique described in Japanese Patent Application Laid-Open No. 2011-186437 is a film forming method using a reactive epoxy paint, it is not suitable for a film forming method using an ink jet method.

In view of the above, the present disclosure includes a specific amount of titanium dioxide particles from the viewpoint of increasing the refractive index while having a black color tone as an ink composition having a black color tone that can be applied to the inkjet method, and In addition, the carbon black particles and the titanium dioxide particles are contained in a ratio in which the titanium dioxide particles are larger than the carbon black particles. In addition, a basic dispersant is selectively used from the viewpoint of favorably dispersing two different types of carbon black particles and titanium dioxide particles.
Thereby, it is possible to achieve both ink jet aptitude and high refractive index while achieving a black color tone. In other words, the black ink composition for inkjet according to the present disclosure can ensure the inkjet suitability and drastically increase the refractive index of the film while providing the film with light absorptivity (light-shielding property). Can be increased.

Hereinafter, each component included in the black ink of the present disclosure will be described.
-Carbon black particles-
The black ink of the present disclosure contains at least one kind of carbon black particles.
The black ink of the present disclosure contains carbon black as a particle component as a black coloring component.

There is no restriction | limiting in particular as carbon black, Well-known carbon black can be used. Examples of carbon black include those produced by known methods such as a contact method, a furnace method, and a thermal method.
Specific examples of carbon black, Raven1250, Raven1200, Raven1190 ULTRA, Raven1170, Raven1255, Raven1080ULTRA, Raven1060ULTRA, Raven1040, Raven1035, Raven1020, Raven1000, Raven900, Raven890, Raven850, Raven780ULTRA, Raven860Ultra, Raven520, Raven500, Raven450, Raven460, Raven415 , Raven 14, Conductex 7055 Ultra (above, manufactured by Columbian Carbon), Regal 400R, Regal 330R, Regal 660R, Mogu L, Black Pea rls L, Regal99, Regal350, MONARCH280, MONARCH120 (manufactured by Cabot), Color Black S160, Color Black S170, Printex35, Printex U, Printex V, Printex 140U, PrintP 140, U 5, Special Black 4A, Special Black 4, Special Black 550, Special Black 350, Special Black 250, Special Black 100, NEROX 3500, NEROX 1000, NEROX 2500 Orion Engineered made of carbon, Inc.), No. 10, no. 20, no. 25, no. 33, no. 40, no. 45, no. 47, no. 52, no. 85, no. 95, no. 260, MA7, MA8, MA11, MA77, MA100, MA220, MA230, MA600 (above, manufactured by Mitsubishi Chemical Corporation).
However, the present disclosure is not limited to these.

The average primary particle size of carbon black is preferably 20 nm to 100 nm, and more preferably 30 nm to 80 nm.
The average primary particle size is a particle size (area equivalent circle diameter) of 1000 primary particles arbitrarily selected from an image taken using a transmission electron microscope TEM2010 (pressurized voltage 200 kV; manufactured by JEOL Ltd.). It is a value that is measured and calculated as its arithmetic average. That is, the average primary particle diameter represents the arithmetic average particle diameter of the equivalent area circle diameter.

The amount of dibutyl phthalate (DBP) absorption of carbon black is not particularly limited, and is preferably from 30 ml / 100 g to 200 ml / 100 g, more preferably from 40 ml / 100 g to 150 ml / 100 g from the viewpoint of color tone and ink density. preferable.
The DBP absorption is a value measured by JIS K6221 A method (1982).

The BET specific surface area of carbon black is preferably 30 m ² / g or more and 450 m ² / g or less, more preferably 200 m ² / g or more and 400 m ² / g or less, from the viewpoint of ink concentration and storage stability.

The content of the carbon black particles is preferably 1% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 6% by mass or less with respect to the total mass of the black ink composition for inkjet. More preferably, it is 1 mass% or more and 4 mass% or less.
When the content of the carbon black particles is 1% by mass or more, it is easy to adjust to a desired black color tone. For example, when a light shielding film is formed, light shielding performance is easily imparted. Further, when the content of the carbon black particles is 10% by mass or less, good stability over time is easily obtained. The content of carbon black particles is more preferably 7% by mass or less from the viewpoint of stability over time.

-Titanium dioxide particles-
The black ink according to the present disclosure contains at least one kind of titanium dioxide particles.
The black ink of the present disclosure contains titanium dioxide as a particle component, and the shape of the titanium dioxide particles contained therein is not particularly limited, and may be any of granular or needle-like shapes.

The crystal structure of titanium dioxide includes rutile type (tetragonal crystal), anatase type (tetragonal crystal), and brookite type (orthorhombic crystal), and is not particularly limited. Among these, preferable titanium dioxide is preferably rutile titanium dioxide from the viewpoints of crystal stability and availability.
Titanium dioxide can be produced by a gas phase method or a liquid phase method. Titanium dioxide produced by a vapor phase method is preferable in that a highly crystalline material is easily obtained. Titanium dioxide can be either untreated or surface-treated. As surface treatment when titanium dioxide is surface-treated, surface treatment with an inorganic material such as alumina (Al ₂ O ₃ ) or silica (SiO ₂ ), or titanium coupling agent, silane coupling agent, silicone oil, etc. Examples include surface treatment with an organic substance.

Titanium dioxide has organic substance decomposability due to photocatalytic activity, so the surface of the particles was surface-treated with an inorganic oxide such as alumina or coated with an inorganic hydrate containing zinc, magnesium, zirconium, etc. Those are preferred. Moreover, the thing which surface-treated using alumina and silica together from the point which adjusts the acidic or basic state of the particle | grain surface, and a durable point is also preferable.

A commercially available titanium dioxide may be used.
Examples of commercially available rutile-type titanium dioxide include Typek (registered trademark) R series (rutile type; for example, R-550, R-630, R-680, R-820) manufactured by Ishihara Sangyo Co., Ltd., and Taipei CR series (Rutile type; for example, CR-50, CR-80), PF series, ultrafine titanium oxide TTO series (rutile type; for example, TTO-51 series (eg, TTO-51A, TTO-51B, etc.), TTO- 55 series (eg TTO-55A, TTO-55B etc.), TTO-S series (eg TTO-S-1 etc.), TTO-V series (eg TTO-V-3 etc.), TTO-F series, TTO-W-5 series), Sakai Chemical Industry Co., Ltd. trade name: R series, Takeka Co., Ltd. JR series, MT series, fine particle titanium oxide MT series (For example, MT-01, MT-10EX, MT-05, MT-100S, MT-100SA, MT-500SA, MT-150EX, MT-150W), KURONOS KR series manufactured by Titanium Industry Co., Ltd., Fuji Titanium Examples include TR series manufactured by Kogyo Co., Ltd.

The average primary particle diameter of the titanium dioxide particles is preferably 10 nm or more and 300 nm or less, and is 10 nm or more and 100 nm or less from the viewpoint of high transparency, hardly affecting the color tone and refractive index, and excellent dispersibility. Preferably, it is 10 nm or more and 80 nm or less, and more preferably 30 nm or more and 80 nm or less.
The average primary particle diameter of titanium dioxide is a particle diameter (corresponding to an area circle) of 1000 primary particles arbitrarily selected from an image taken using a transmission electron microscope TEM2010 (pressurized voltage 200 kV; manufactured by JEOL Ltd.). It is a value calculated as an arithmetic average by measuring the diameter. The average primary particle diameter here represents the arithmetic average particle diameter of the equivalent area circle diameter.

The mass ratio of the content of titanium dioxide particles to the content of the carbon black particles described above is in the range of 2.0 to 15.0.
When the content ratio of the titanium dioxide particles to the carbon black particles is 2.0 or more, a high refractive index (refractive index of 1.75 or more) is easily obtained, and good stability over time is easily obtained. Further, when the content ratio of the titanium dioxide particles to the carbon black particles is 15.0 or less, the influence on the black coloring by the carbon black particles is small, and a desired black tone is easily obtained, so that the light shielding property is easily maintained. .
Among these, the content ratio of the titanium dioxide particles to the carbon black particles is preferably 3.0 or more and 13.0 or less, and more preferably 3.0 or more and 10.0 or less, for the same reason as described above.

The content of the titanium dioxide particles is in the range of 15% by mass to 45% by mass with respect to the total mass of the black ink composition for inkjet. When the content of the titanium dioxide particles is 15% by mass or more, a high refractive index (refractive index of 1.75 or more) can be easily obtained, which is advantageous in terms of stability over time of the black ink. Further, when the content of the titanium dioxide particles is 45% by mass or less, good stability over time is easily obtained.
Especially, as content of a titanium dioxide particle, the range of 20 mass% or more and 35 mass% or less is more preferable from the reason similar to the above, and the range of 23 mass% or more and 32 mass% or less is still more preferable.

-Basic dispersant-
The black ink of the present disclosure contains at least one basic dispersant. When a basic dispersant is contained, the basic polar functional group in the molecule tends to act on the particle surface, and when both titanium dioxide particles and carbon black particles are used in combination, the dispersion stability of both can be kept good. It is.

The basic dispersant is a polymer having a basic polar functional group, and has a weight average molecular weight of 1,000 or more. The weight average molecular weight is a value measured by GPC. Details of the measuring method will be described in detail in the section of the photocurable resin described later.

Examples of the basic polar functional group in the basic dispersant include an amino group, an imino group, an amide group, an imide group, and a nitrogen-containing heterocyclic group. Among these, an amino group is preferable from the viewpoint of dispersibility.

The amine value of the basic dispersant can be selected in the range of 10 mgKOH / g to 150 mgKOH / g, and preferably 10 mgKOH / g to 80 mgKOH / g.
When the amine value is 10 mgKOH / g or more, the dispersibility of both the carbon black particles and the titanium dioxide particles can be maintained well, and a high refractive index is easily obtained. Further, when the amine value is 150 mgKOH / g or less, aggregation of the carbon black particles and titanium dioxide particles can be suppressed, and the stability over time can be favorably maintained, and a high refractive index can be easily secured.
Among them, the amine value is more preferably 10 mgKOH / g or more and 50 mgKOH / g or less in view of the temporal stability of the black ink because a high refractive index is obtained.

The amine value indicates the total amount of free base and base, and is expressed in mg of potassium hydroxide equivalent to the hydrochloric acid required to neutralize 1 g of the sample.
The amine value is a value measured by a method according to JIS-K7237 (1995).

Examples of the basic dispersant include a salt of a long-chain polyaminoamide and a high molecular weight acid ester; a salt of a long-chain polyaminoamide and a polar acid ester; a polyester polyamine; a stearylamine acetate; an unsaturated carboxylic acid such as polyacrylic acid (Partial) amine salt, (partial) ammonium salt or (partial) alkylamine salt; unsaturated polyamide; long-chain polyaminoamide phosphate; polyethyleneimine compound [eg: poly lower alkyleneimine and Amide that is a reaction product with a polyester containing a free carboxy group]; a polyallylamine-based compound (eg, polyallylamine and a polyester having a free carboxyl group, polyamide, and polyesteramide (co-condensate of ester and amide)) Reaction with at least one compound Narubutsu] and the like.
Among these, a compound having a polyester polyamine skeleton or a compound having a polyethyleneimine skeleton is preferable, and a compound having a polyethyleneimine skeleton is preferable.

As the basic dispersant, a commercially available product may be used.
Examples of commercially available products include Solsperse series manufactured by Nippon Ruble Resor Co., Ltd. [for example, trade name: Solsperse 24000 (amine value: 41.6 mgKOH / g), trade name: Solsperse 32000 (amine value: 31.2 mgKOH / g) ), Trade name: Solsperse 35100 (amine value: 14 mgKOH / g), trade name: Solsperse 39000 (amine value: 35.7 mgKOH / g), trade name: Solsperse 71000 (amine value: 78 mgKOH / g), trade name: Solsperse J100, trade name: Solsperse J200, etc.], DisperBYK series (trade name: DisperBYK-109 (amine value: 140 mgKOH / g), DisperBYK-162 (amine value: 13 mgKOH / g) manufactured by Big Chemie Japan Co., Ltd. , Trade name: DisperBYK-163 (amine value: 10 mgKOH / g), trade name: DISPERBYK-168 (amine value: 11 mgKOH / g), trade name: DISPERBYK-2050 (amine value: 30.7 mgKOH / g), trade name : DISPERBYK-2200 (30.7 mgKOH / g), trade name: DISPERBYK-2150 (amine value: 56.7 mgKOH / g), etc.], BYKJET series manufactured by Big Chemie Japan KK [trade name: BYKJET-9151 (amine value) : 17.2 mg KOH / g), trade name: BYKJET-9152 (amine value: 27.3 mg KOH / g), etc.], Ajinomoto Fine Techno Co., Ltd. Ajisper series [trade name: Ajisper PB821 (amine number: 11.2 mgKOH) / G , Trade name: Azisper PB-822 (amine value: 18.2 mgKOH / g), trade name: Azisper PB-881 (amine value: 17.4 mgKOH / g), trade name: Azisper PB-824 (amine value: 17 mgKOH / g) g) and the like], and EFKA PX4731 (amine value: 25 mgKOH / g) manufactured by BASF.

The content of the basic dispersant in the black ink composition for inkjet is preferably 3% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less with respect to the total mass of the ink.
When the content of the basic dispersant is 3% by mass or more, it is suitable for maintaining good dispersion stability when both titanium dioxide particles and carbon black particles are used in combination. Further, when the content of the basic dispersant is 20% by mass or less, it is advantageous from the viewpoint of inkjet ejection stability.

-Organic solvent with boiling point of 120 ° C or higher-
The black ink of the present disclosure preferably contains an organic solvent having a boiling point of 120 ° C. or higher. When an organic solvent having a boiling point of 120 ° C. or higher is contained, the black ink of the present disclosure contains a relatively large amount of pigment particles, but it is easy to keep the ink viscosity low and to easily suppress an increase in the viscosity of the ink composition.

Examples of the organic solvent having a boiling point of 120 ° C. or higher include ethylene glycol monomethyl ether (boiling point: 124 ° C.), ethylene glycol monomethyl ether acetate (boiling point: 143 ° C.), propylene glycol methyl ether acetate (boiling point: 146 ° C.), diethylene glycol dimethyl ether. (Boiling point: 162 ° C), diethylene glycol diethyl ether (DEGdEE) (boiling point: 180 ° C), diethylene glycol ethyl methyl ether (boiling point: 179 ° C), diethylene glycol monobutyl ether (boiling point: 230 ° C), diethylene glycol dibutyl ether (boiling point: 255 ° C) Glycol ether solvents such as triethylene glycol dimethyl ether (boiling point: 216 ° C); methyl benzoate (boiling point: 199 ° C), ethyl benzoate Boiling point: 213 ° C), alkyl benzoate solvents such as butyl benzoate (boiling point: 250 ° C); γ-butyrolactone (boiling point: 204 ° C), 1,3-butanediol (boiling point: 208 ° C), cyclohexanone (boiling point: 156) ° C), terpineol (boiling point: 218 ° C), phenetole (boiling point: 170 ° C), isophorone (boiling point: 215 ° C), 1,4-butanediol diacetate (boiling point: 232 ° C), 1,3-butylene glycol diacetate (Boiling point: 232 ° C.).
Two or more organic solvents are preferably used in combination. By using two or more organic solvents in combination, it becomes possible to change the surface tension after image formation and after drying, and the patternability during image formation can be improved.

When two or more organic solvents are used in combination, from the viewpoint of controlling the drying rate, among the two or more organic solvents having a boiling point of 120 ° C. or higher, the boiling point of one organic solvent is BPa, and the other one organic When the boiling point of the solvent is BPb, it is preferable to satisfy the relationship represented by the following formula.
120 ° C <BPa <BPb <250 ° C
Furthermore, it is preferable to satisfy the relationship represented by the following formula.
150 ° C <BPa <BPb <230 ° C
The absolute value of the difference between BPa and BPb is preferably 10 ° C to 50 ° C.
The boiling point means a boiling point under 1 atm (101325 Pa).
The boiling point is a value measured by a boiling point meter, and can be measured, for example, using DosaTherm300 manufactured by Titan Technologies.

Further, when two or more organic solvents are used in combination, the surface tension of one organic solvent among two or more organic solvents having a boiling point of 120 ° C. or higher is expressed as γa ( mN / m), and when the surface tension of the other organic solvent is γb (mN / m), the relationship represented by the following formula is preferably satisfied.
γa <γb
Furthermore, it is preferable to satisfy the relationship represented by the following formula.
γa <30 mN / m <γb
The surface tension of the organic solvent is a value measured using a surface tension meter (DY-700, Kyowa Interface Chemical Co., Ltd.) at a liquid temperature of 30 ° C.

As the organic solvent having a high surface tension (preferably having a surface tension exceeding 30 mN / m), the following solvents are preferable.

Among organic solvents having a high surface tension, at least one selected from γ-butyrolactone, methyl benzoate, 1,3 butanediol, ethyl benzoate, butyl benzoate, terpineol, and isophorone is preferable. Γ-butyrolactone, methyl benzoate , 1,3 butanediol, terpineol, and isophorone are more preferable.

When two or more organic solvents are used, it is preferable to use two organic solvents having an absolute value of the difference in surface tension of 5 mN / m to 20 mN / m in combination.

When the black ink of the present disclosure contains an organic solvent, the content of the organic solvent is preferably 10% by mass to 55% by mass with respect to the total mass of the black ink composition for inkjet. 30% by mass to 50% by mass is more preferable, and 35% by mass to 45% by mass is even more preferable.
When the content of the organic solvent is 10% by mass or more, it is easy to maintain the viscosity of the ink composition itself at a viscosity suitable for ejection by the inkjet method. Moreover, when the content of the organic solvent is 55% by mass or less, it is advantageous in that the black ink has better stability over time and can be easily dried after ejection.

-Curing compound-
The black ink of the present disclosure preferably contains a curable compound in addition to the above components and is prepared to be curable. When the black ink has curability, adhesion to a non-absorbing substrate (for example, glass or plastic) is improved, and the durability is excellent.

The curable compound is preferably at least one compound selected from a photocurable monomer and a photocurable resin.

(Photocurable monomer)
The photocurable monomer refers to a polymerizable monomer having a polymerizable group, and includes a monofunctional polymerizable monomer and a polyfunctional polymerizable monomer. The polymerizable group is a group having an ethylenically unsaturated double bond.

The black ink of the present disclosure preferably contains at least one monomer selected from a monofunctional polymerizable monomer and a polyfunctional polymerizable monomer, and is selected from a monofunctional polymerizable monomer and a bifunctional polymerizable monomer. More preferably, it contains a monomer. The black ink of the present disclosure can also contain a tri- or higher functional polymerizable monomer.
Furthermore, the aspect of the black ink of the present disclosure is:
1) It may be an embodiment containing at least one monofunctional polymerizable monomer and not containing a bifunctional polymerizable monomer,
2) It may be an embodiment containing at least one bifunctional polymerizable monomer and not containing a monofunctional polymerizable monomer,
3) It may be an embodiment containing both at least one monofunctional polymerizable monomer and at least one bifunctional polymerizable monomer.

The polymerizable monomer can have a function of maintaining the liquid state of the ink in addition to a function of imparting photocurability (that is, a property of being cured by light) to the black ink.

As a monofunctional polymerizable monomer,
N-vinyl compounds such as N-vinylcaprolactam and N-vinylpyrrolidone;
2-phenoxyethyl acrylate (PEA), benzyl acrylate, cyclic trimethylolpropane formal acrylate (CTFA), isobornyl acrylate (IBOA), tetrahydrofurfuryl acrylate, 2- (2-ethoxyethoxy) ethyl acrylate, octyl acrylate, Decyl acrylate, tridecyl acrylate, isodecyl acrylate, lauryl acrylate, 3,3,5-trimethylcyclohexyl acrylate (TMCHA), dicyclopentenyl acrylate (DCPA), 4-t-butylcyclohexyl acrylate, cyclohexyl acrylate, caprolactone-modified acrylate, Hydroxyethyl acrylate, hydroxybutyl acrylate, polyethylene glycol acrylate Polypropylene glycol acrylate, nonylphenoxy polyethylene glycol acrylate, monofunctional acrylate compounds such as nonylphenoxy polypropylene glycol acrylate;
2-phenoxyethyl methacrylate, benzyl methacrylate, isobornyl methacrylate (IBOA), tetrahydrofurfuryl methacrylate, 2- (2-ethoxyethoxy) ethyl methacrylate, octyl methacrylate, decyl methacrylate, tridecyl methacrylate, isodecyl methacrylate, lauryl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate (TMCHA), dicyclopentenyl methacrylate (DCPA), 4-t-butylcyclohexyl methacrylate, cyclohexyl methacrylate, caprolactone-modified methacrylate, hydroxyethyl methacrylate, hydroxybutyl methacrylate, polyethylene glycol methacrylate, polypropylene glycol Methacryle DOO, nonylphenoxy polyethylene glycol methacrylate, a monofunctional methacrylate compound such as nonylphenoxy polypropylene glycol methacrylate;
Monofunctional vinyl ether compounds such as normal propyl vinyl ether, isopropyl vinyl ether, normal butyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, cyclohexanedimethanol monovinyl ether;
Acrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, acryloylmorpholine, N-isopropylacrylamide, N-hydroxyethylacrylamide, N-butylacrylamide, N-tert-butylacrylamide, N- (1,1-dimethyl) Monofunctional acrylamide compounds such as -3-oxobutyl) acrylamide, N-dodecylacrylamide, N- (butoxymethyl) acrylamide;
Monofunctional methacrylamide compounds such as methacrylamide, N-phenylmethacrylamide, N- (methoxymethyl) methacrylamide, N, N-dimethylmethacrylamide, N-tert-butylmethacrylamide, etc .;
Etc.

As a bifunctional polymerizable monomer,
Hexanediol diacrylate (HDDA), dipropylene glycol diacrylate (DPGDA), polyethylene glycol diacrylate, polypropylene glycol diacrylate, nonanediol diacrylate, decanediol diacrylate, neopentyl glycol diacrylate, polyethylene glycol modified bisphenol A diacrylate Bifunctional acrylate compounds such as dioxane glycol diacrylate, cyclohexane dimethanol diacrylate, tricyclodecane dimethanol diacrylate; 2- (2-vinyloxyethoxy) ethyl acrylate (VEEA);
Bifunctional vinyl compounds such as 1,4-butanediol divinyl ether, cyclohexanedimethanol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether (DVE3);
Bifunctional methacrylate compounds such as hexanediol dimethacrylate, dipropylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, noneopentyl glycol dimethacrylate, polyethylene glycol modified bisphenol A dimethacrylate;
Etc.

As the photocurable monomer, in addition to the monofunctional polymerizable monomer and the bifunctional polymerizable monomer described above, Shinzo Yamashita, “Crosslinker Handbook”, (1981 Taiseisha); UV / EB Curing Handbook (Raw Materials) "(1985, Polymer Press Society); Radtech Research Group," Application and Market of UV / EB Curing Technology ", p. 79, (1989, CMC); Eiichiro Takiyama A commercially available product described in the book “Polyester Resin Handbook”, (1988, Nikkan Kogyo Shimbun), or a monofunctional or bifunctional polymerizable monomer known in the industry can be used.

The weight average molecular weight of the photocurable monomer is preferably 100 or more and less than 1,000, more preferably 100 or more and 800 or less, and further preferably 150 or more and 700 or less.

The content of the photocurable monomer in the black ink of the present disclosure is preferably 5% by mass or more, and more preferably 10% by mass or more with respect to the total mass of the black ink. Moreover, there is no restriction | limiting in particular about the upper limit of content of a polymerizable monomer, For example, it can be 95 mass% or less, can be 50 mass% or less, and can be 20 mass% or less.

(Photo-curing resin)
The photocurable resin refers to a polymerizable resin that has a polymerizable group and is cured by a polymerization reaction with light. An oligomer having a polymerizable group (photocurable oligomer) and a polymer having a polymerizable group (photocuring) Polymer). The polymerizable group is a group having an ethylenically unsaturated double bond.

Examples of the resin serving as the base of the photocurable resin include acrylic resins, urethane resins, polyester resins, polyether resins, polycarbonate resins, epoxy resins, polybutadiene resins, and the like. Among these, from the viewpoint of reducing curing shrinkage, a resin that has both a hard segment and a soft segment and can relieve stress at the time of curing is preferable, and in particular, at least one resin selected from urethane resin, polyester resin, and epoxy resin It is more preferable that

The polymerizable group contained in the photocurable resin is preferably a group containing an ethylenic double bond, and more preferably a group containing at least one of a vinyl group and a 1-methylvinyl group.
As the polymerizable group, a (meth) acryloyl group is particularly preferable from the viewpoints of polymerization reactivity and the hardness of the formed film.

These polymerizable groups can be introduced into a resin (polymer or oligomer) by polymer reaction or copolymerization.
For example, a reaction between a polymer (or oligomer) having a carboxy group in the side chain and glycidyl methacrylate, or a reaction between a polymer (or oligomer) having an epoxy group and an ethylenically unsaturated group-containing carboxylic acid such as methacrylic acid is used. Thus, a polymerizable group can be introduced into the polymer (or oligomer). These groups may be used in combination.

A commercially available product may be used as the photocurable resin.
Examples of commercially available acrylic resins having a polymerizable group include (ACA) Z200M, (ACA) Z230AA, (ACA) Z251, (ACA) Z254F (above, Daicel Ornex Co., Ltd.), Hitaroid 7975D (Hitachi Chemical) Etc.).

Examples of commercially available urethane resins having a polymerizable group include EBECRYL (registered trademark) 8402, EBECRYL (registered trademark) 8405, EBECRYL (registered trademark) 9270, EBECRYL (registered trademark) 8311, EBECRYL (registered trademark) 8701, KRM8667, KRM8528 (above, Daicel Ornex Co., Ltd.), CN964, CN9012, CN968, CN996, CN975, CN9782 (above, Sartomer), UV-6300B, UV-7600B, UV-7605B, UV-7620EA, UV- 7630B, UV-1700B (above, Nippon Synthetic Chemical Co., Ltd.), U-6HA, U-15HA, U-108A, U-200PA, UA-4200 (above, Shin-Nakamura Chemical Co., Ltd.), Teslac 2300, Hitaroy 4863, Teslak 2328, Teslak 2350, Hytaroid 7902-1 (Hitachi Chemical Co., Ltd.), 8UA-017, 8UA-239, 8UA-239H, 8UA-140, 8UA-585H, 8UA-347H, 8UX-015A ( As mentioned above, Taisei Fine Chemical Co., Ltd.) and the like can be mentioned.

Examples of commercially available polyester resins having a polymerizable group include CN294, CN2254, CN2260, CN2271E, CN2300, CN2301, CN2302, CN2303, CN2304 (above, Sartomer), EBECRYL (registered trademark) 436, EBECRYL (registered trademark). 438, EBECRYL (registered trademark) 446, EBECRYL (registered trademark) 524, EBECRYL (registered trademark) 525, EBECRYL (registered trademark) 811, EBECRYL (registered trademark) 812 (above, Daicel Ornex Co., Ltd.) It is done.
Examples of commercially available polyether resins having a polymerizable group include Blemmer (registered trademark) ADE-400A, Blemmer (registered trademark) ADP-400 (above, NOF Corporation) and the like.
An example of a commercially available polycarbonate resin having a polymerizable group is polycarbonate diol diacrylate (Ube Industries, Ltd.).
Examples of commercially available epoxy resins having a polymerizable group include EBECRYL (registered trademark) 3708 (Daicel Ornex Co., Ltd.), CN120, CN120B60, CN120B80, CN120E50 (above, Sartomer), Hitaroid 7851 (Hitachi Chemical ( Etc.).
Examples of commercially available polybutadiene resins having a polymerizable group include CN301, CN303, CN307 (Sertmer).

The weight average molecular weight of the photocurable resin is preferably 1000 or more and 100000 or less, more preferably 1000 or more and 40000 or less, and still more preferably 1000 or more and 10,000 or less, from the viewpoint of compatibility between adhesion and dispersion stability. .

The weight average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC).
In the measurement by gel permeation chromatography (GPC), HLC (registered trademark) -8020GPC (Tosoh Corp.) was used as a measuring device, and TSKgel (registered trademark) Super Multipore HZ-H (4.6 mmID ×) was used as a column. 15 cm, Tosoh Corp.) are used, and THF (tetrahydrofuran) is used as an eluent. As measurement conditions, the sample concentration is 0.45 mass%, the flow rate is 0.35 ml / min, the sample injection amount is 10 μl, the measurement temperature is 40 ° C., and the measurement is performed using an RI detector.
The calibration curve is “Standard sample TSK standard, polystyrene” of Tosoh Corporation: “F-40”, “F-20”, “F-4”, “F-1”, “A-5000”, “A -2500 "," A-1000 ", and" n-propylbenzene ".

When the ink composition of the present disclosure contains a photocurable resin, the content of the photocurable resin is preferably 5% by mass or more, and more preferably 10% by mass or more. Moreover, there is no restriction | limiting in particular about the upper limit of content of photocurable resin, For example, it can be 95 mass% or less, can be 50 mass% or less, and can be 20 mass% or less. .

-Photopolymerization initiator-
The black ink of the present disclosure preferably further contains a photopolymerization initiator.
As the photopolymerization initiator, known photopolymerization initiators that absorb active energy rays and generate radicals that are polymerization initiation species can be used.

Examples of active energy rays include ultraviolet rays (UV), visible rays, and electron beams. Among these, ultraviolet rays are preferable from the viewpoint of versatility.

Photopolymerization initiators include (a) carbonyl compounds such as aromatic ketones, (b) acylphosphine oxide compounds, (c) aromatic onium salt compounds, (d) organic peroxides, (e) thio compounds, (F) hexaarylbiimidazole compound, (g) ketoxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, (k) active ester compound, (l) having a carbon halogen bond Compounds, (m) alkylamine compounds, and the like.
As the photopolymerization initiator, the compounds (a) to (m) may be used singly or in combination of two or more.

Preferred examples of (a) carbonyl compounds, (b) acylphosphine oxide compounds, and (e) thio compounds include “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY”, J. MoI. P. FOUASSIER, J.A. F. RABEK (1993), pp. And compounds having a benzophenone skeleton or a thioxanthone skeleton described in 77-117.
More preferred examples include α-thiobenzophenone compounds described in JP-B-47-6416, benzoin ether compounds described in JP-B-47-3981, α-substituted benzoin compounds described in JP-B-47-22326, Benzoin derivatives described in JP-B-47-23664, aroylphosphonic acid esters described in JP-A-57-30704, dialkoxybenzophenones described in JP-B-60-26483, JP-B-60-26403, Benzoin ethers described in JP-A-62-81345, JP-B-1-34242, US Pat. No. 4,318,791 pamphlet, and α-aminobenzophenones described in European Patent 0284561A1, JP-A-2-21152 P-di (dimethylamino) Nzoyl) benzene, thio-substituted aromatic ketone described in JP-A-61-194062, acylphosphine sulfide described in JP-B-2-9597, acylphosphine described in JP-B-2-9596, JP-B-63-61950 And the coumarins described in JP-B-59-42864.
Also preferred are polymerization initiators described in JP-A-2008-105379 and JP-A-2009-114290.

Among the photopolymerization initiators, (a) a carbonyl compound or (b) an acylphosphine oxide compound is more preferable. Specifically, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (for example, manufactured by BASF) IRGACURE® 819), 2- (dimethylamine) -1- (4-morpholinophenyl) -2-benzyl-1-butanone (eg, IRGACURE® 369 manufactured by BASF), 2-methyl 1- (4-methylthiophenyl) -2-morpholinopropan-1-one (for example, IRGACURE® 907 manufactured by BASF), 1-hydroxy-cyclohexyl-phenyl-ketone (for example, manufactured by BASF) IRGACURE (registered trademark) 184), 1- [4- (2-hydroxyeth Cis-phenyl] -2-hydroxy-2-methyl-1-propan-1-one (for example, IRGACURE® 2959 manufactured by BASF), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (For example, DAROCUR (registered trademark) TPO, LUCIRIN (registered trademark) TPO (both manufactured by BASF)) and the like.
Among these, from the viewpoint of improving sensitivity and adaptability to LED light, as the photopolymerization initiator, (b) acylphosphine oxide compounds are preferable, and monoacylphosphine oxide compounds (particularly preferably 2, 4). , 6-trimethylbenzoyl-diphenyl-phosphine oxide) or a bisacylphosphine oxide compound (particularly preferably bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide).

A photoinitiator may be used only by 1 type and may use 2 or more types together.
When the black ink of the present disclosure contains a photopolymerization initiator, the content of the photopolymerization initiator is 0.5% by mass to 25.0% by mass with respect to the total mass of the black ink composition for inkjet. %, More preferably 0.5% by mass to 20.0% by mass, and still more preferably 1.0% by mass to 15.0% by mass.

-Other ingredients-
The black ink of the present disclosure can further contain other components as necessary in addition to the above-described components.

(Coloring agent)
The black ink of the present disclosure may contain at least one colorant as long as the black color tone and high refractive index are not impaired.
As a coloring agent, it can select arbitrarily from well-known color materials, such as pigments and dyes other than said carbon black and titanium dioxide.
However, since the black ink of the present disclosure has a composition using carbon black particles and titanium dioxide particles from the viewpoint of ensuring a high refractive index while having a black color tone, the content of the colorant is Less is preferred. In particular, the content of the dye is preferably less than 10% by mass, more preferably less than 1% by mass, and still more preferably less than 0.1% by mass with respect to the total mass of the black ink. A dye content of less than 10% by weight indicates that the composition does not contain much dye, and a dye content of less than 0.1% by weight substantially contains a dye. Indicates not.

There is no restriction | limiting in particular as a pigment, According to the objective, it can select suitably, For example, a well-known organic pigment, an inorganic pigment, etc. are mentioned. In addition, resin particles dyed with dyes, commercially available pigment dispersions and surface-treated pigments (for example, pigments dispersed in water, liquid compounds, insoluble resins, etc., and resins and pigment derivatives) And the like which have been treated with a pigment surface).
Examples of organic pigments and inorganic pigments include yellow pigments, red pigments, magenta pigments, blue pigments, cyan pigments, green pigments, orange pigments, purple pigments, brown pigments, black pigments, and white pigments.
When a pigment is used as the colorant, a pigment dispersant may be used as necessary when preparing the pigment particles.
Regarding the colorant such as pigment and the pigment dispersant, publicly known documents such as paragraphs 0152 to 0158 of JP2011-225848A and paragraphs 0132 to 0149 of JP2009-209352A can be appropriately referred to.

When the black ink of the present disclosure contains a colorant (excluding a dye), the content of the colorant is, for example, 0.1% by mass to 20% by mass with respect to the total mass of the black ink. it can.
The black ink of the present disclosure is also preferably used as an ink that does not substantially contain a colorant. Here, “substantially does not contain” means that the content of the colorant is less than 0.1% by mass with respect to the total mass of the black ink.

(binder)
When the black ink of the present disclosure does not contain a curable compound, it can contain a binder.
As the binder, a known binder polymer such as polyester resin, polyurethane resin, vinyl resin, acrylic resin, rubber resin, etc. can be used. Among them, acrylic resin or polyester resin is preferable and inert, methyl methacrylate alone More preferred are polymers and / or copolymers.
A commercially available binder may be used, for example, polymethyl methacrylate (molecular weight 10,000, catalog number 81497; molecular weight 20,000, catalog number 81498; molecular weight 50,000, catalog number 81501) manufactured by Aldrich. ), Methyl methacrylate / n-butyl methacrylate copolymer (mass ratio 85/15, molecular weight 75,000; catalog number 474029), etc .; Lucite Intenal
ELVACITE 2013 (Methyl methacrylate / n-butyl methacrylate copolymer, mass ratio 36/64, molecular weight 37,000), 2021, 614, 4025, 4026, 4028, etc .; Paramid DM55, B manufactured by Rohm and Haas
66 etc .; Mitsubishi Rayon Co., Ltd. BR113, 115 etc. are mentioned.
The weight average molecular weight (Mw) of the binder polymer is preferably 1,000 or more, more preferably 1,000 to 1,000,000, and still more preferably 5,000 to 200,000. 8,000 to 100,000 is particularly preferable.
In addition, a weight average molecular weight is a value measured by GPC, and the measuring method is the same as that of the above-mentioned photocurable resin.
The glass transition temperature (Tg) of the binder polymer is preferably 50 to 120 ° C, more preferably 60 to 100 ° C. Tg is a value measured by differential scanning calorimetry (DSC).
A binder polymer may be used individually by 1 type, or may use 2 or more types together.

(Polymerization inhibitor)
The black ink of the present disclosure may contain a polymerization inhibitor.
Polymerization inhibitors include p-methoxyphenol, quinones (eg, hydroquinone, benzoquinone, methoxybenzoquinone, etc.), phenothiazine, catechol, alkylphenols (eg, dibutylhydroxytoluene (BHT), etc.), alkylbisphenols, dimethyldithiocarbamine Zinc oxide, copper dimethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, thiodipropionic acid esters, mercaptobenzimidazole, phosphites, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl (TEMPOL), cuperon Al, tris (N-nitroso-N-phenylhydroxylamine) aluminum salt And the like.
Among these, at least one selected from p-methoxyphenol, catechols, quinones, alkylphenols, TEMPO, TEMPOL, cuperon Al, and tris (N-nitroso-N-phenylhydroxylamine) aluminum salt is preferable.
When the black ink of the present disclosure contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.01% by mass to 2.0% by mass with respect to the total mass of the black ink, and 0.02 A mass% to 1.0 mass% is more preferred.

(Sensitizer)
The black ink of the present disclosure may additionally contain a sensitizer.
A sensitizer is a substance that absorbs specific active energy rays and enters an electronically excited state. The sensitizer brought into the electronically excited state comes into contact with the photopolymerization initiator, and produces effects such as electron transfer, energy transfer, and heat generation. This promotes chemical changes of the photopolymerization initiator, that is, decomposition, generation of radicals, acids or bases, and the like.

Examples of the sensitizer include benzophenone (BP), thioxanthone, isopropylthioxanthone (ITX), ethyl 4- (dimethylamino) benzoate (EDB), anthraquinone, 3-acylcoumarin derivatives, terphenyl, styryl ketone, 3- (Aroylmethylene) thiazoline, camphorquinone, eosin, rhodamine, erythrosine and the like.
Examples of the sensitizer include a compound represented by the general formula (i) described in JP 2010-24276 A and a compound represented by the general formula (I) described in JP 6-107718 A Can also be suitably used.
Among them, the sensitizer is selected from thioxanthone, isopropylthioxanthone, ethyl 4- (dimethylamino) benzoate, and benzophenone from the viewpoint of compatibility with light emitting diode (LED) light and reactivity with a photopolymerization initiator. At least one selected from the above is preferred.
When the black ink of the present disclosure contains a sensitizer, the content of the sensitizer is preferably 0.5% by mass to 10% by mass.

(Surfactant)
The black ink of the present disclosure may contain a surfactant.
Examples of the surfactant include those described in JP-A Nos. 62-173463 and 62-183457. For example, anionic surfactants such as dialkyl sulfosuccinate, alkyl naphthalene sulfonate, fatty acid salt, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, acetylene glycol, polyoxyethylene / polyoxypropylene block copolymer, modified Nonionic surfactants such as siloxanes such as polydimethylsiloxane, cationic surfactants such as alkylamine salts and quaternary ammonium salts, and betaine surfactants such as carbobetaine and sulfobetaine.
When the black ink of the present disclosure contains a surfactant, the content of the surfactant is preferably 0.01% by mass to 5.0% by mass with respect to the total mass of the black ink.

(water)
The black ink of the present disclosure may contain a small amount of water.
The black ink of the present disclosure is preferably a non-aqueous ink that does not substantially contain water. Specifically, the water content with respect to the total mass of the black ink of the present disclosure is preferably 3% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less.

(Other ingredients)
The black ink of the present disclosure may contain other components other than those described above.
Examples of other components include ultraviolet absorbers, co-sensitizers, antioxidants, anti-fading agents, and conductive salts. For other components, publicly known documents such as JP2011-225848A and JP2009-209352A can be referred to as appropriate.

~ Physical properties of black ink composition for inkjet ~
(viscosity)
The viscosity of the black ink composition for inkjet according to the present disclosure at 25 ° C. is preferably 10 mPa · s to 50 mPa · s, more preferably 10 mPa · s to 30 mPa · s, and more preferably 10 mPa · s to 25 mPa · s. More preferably, it is s. The viscosity of the ink can be adjusted, for example, by adjusting the composition ratio of each component contained. When the viscosity of the ink is within the above preferable range, the ejection stability at the time of ejection by the ink jet method can be further improved.
The viscosity is a value measured using a viscometer (VISCOMETER RE-85L, Toki Sangyo Co., Ltd.) with respect to the ink composition temperature-controlled at 25 ° C.

(surface tension)
The surface tension at 30 ° C. of the black ink composition for inkjet according to the present disclosure is preferably 20 mN / m to 30 mN / m, and more preferably 23 mN / m to 28 mN / m. When forming a film on various substrates such as polyolefin, PET, coated paper, and non-coated paper, 30 mN / m or less is preferable in terms of wettability, and 20 mN / m or more in terms of suppression of image bleeding and permeability. preferable.
The surface tension is a value measured using a surface tension meter (DY-700, Kyowa Interface Chemical Co., Ltd.) with respect to the ink composition temperature-controlled at 30 ° C.

<Image forming method>
The black ink of the present disclosure can be suitably used for film formation.
Image formation can be performed by a method using an ink jet method, and preferably, a step of applying the black ink composition for ink jet (black ink) of the present disclosure described above to a substrate by an ink jet method (hereinafter, “ (Also referred to as “applying step”) (an image forming method of the present disclosure).
The image forming method of the present disclosure further includes a step of irradiating the black ink applied onto the substrate with active energy rays (hereinafter also referred to as “irradiation step”) after the application step. Are preferred. By using an ink containing a curable compound as the black ink and providing an irradiation step after the applying step, a film having better adhesion to the substrate can be formed.
The details of the substrate will be described in detail in the section of the light shielding film described later.

(Granting process)
In the applying step, the black ink of the present disclosure is applied onto the substrate by an ink jet method.
The application of the black ink by the ink jet method can be performed using a known ink jet recording apparatus. There is no restriction | limiting in particular as an inkjet recording device, A well-known inkjet recording device can be selected arbitrarily and can be used.

Examples of the ink jet recording apparatus include an apparatus including an ink supply system, a temperature sensor, and a heating unit.
The ink supply system preferably includes, for example, an original tank containing an ink composition, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet head. The piezo-type inkjet head preferably has a multi-size dot of 1 pl to 100 pl (more preferably 8 pl to 30 pl), preferably 320 dpi (dot per inch) × 320 dpi to 4000 dpi × 4000 dpi (more preferably 400 dpi × 400 dpi to 1600 dpi × 1). It is preferable to be able to drive at a resolution of 1600 dpi, more preferably 720 dpi × 720 dpi to 1600 dpi × 1600 dpi).
In addition, dpi represents the number of dots per 2.54 cm (1 inch).

(Irradiation process)
In the irradiation step, the black ink provided on the substrate is irradiated with active energy rays.
By irradiating the black ink with active energy rays, the polymerization reaction of the curable compound in the black ink proceeds. As a result, the film (for example, image) can be cured and fixed, and the film strength can be improved.

Examples of the active energy rays irradiated in the irradiation step include ultraviolet rays (UV), visible rays, and electron beams. Among these, ultraviolet rays are preferable from the viewpoint of versatility.
The peak wavelength of the active energy ray is preferably 200 nm to 405 nm, more preferably 220 nm to 390 nm, and further preferably 220 nm to 385 nm.

Illuminance on the irradiated surface of the active energy ray is irradiated, for ^example, preferably 10mW / cm 2 ~ 2000mW / cm 2, 20mW / cm 2 ~ 1000mW / cm 2 is more preferable.

Examples of the light source for irradiating active energy rays include a mercury lamp, a metal halide lamp, an ultraviolet (UV) fluorescent lamp, a gas laser, and a solid laser. Further, replacement of the exemplified light source with a semiconductor ultraviolet light emitting device is useful in terms of industry and environment.
Among semiconductor ultraviolet light emitting devices, LEDs (Light Emitting Diodes) and LDs (Laser Diodes) are expected to be light sources because of their small size, long life, high efficiency, and low cost.
Among the above, the light source is preferably a metal halide lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, an intermediate pressure mercury lamp, a low pressure mercury lamp, an LED, or a blue-violet laser. Among them, when a sensitizer and a photopolymerization initiator are used in combination, an ultrahigh pressure mercury lamp capable of irradiating light with a wavelength of 365 nm, 405 nm or 436 nm, a high pressure mercury lamp capable of irradiating with a wavelength of 365 nm, 405 nm or 436 nm, Alternatively, an LED capable of emitting light with a wavelength of 355 nm, 365 nm, 385 nm, 395 nm, or 405 nm is more preferable, and an LED capable of emitting light with a wavelength of 355 nm, 365 nm, or 385 nm is most preferable.

In the irradiation step, the irradiation time of the active energy ray with respect to the ink composition applied on the substrate can be, for example, 0.01 seconds to 120 seconds, and preferably 0.1 seconds to 90 seconds.
As irradiation conditions and basic irradiation methods, the irradiation conditions and irradiation methods disclosed in JP-A-60-132767 can be similarly applied.
As an active energy ray irradiation method, specifically, a light source is provided on both sides of a head unit including an ink composition discharge device, and the head unit and the light source are scanned by a so-called shuttle method, or another method that does not involve driving is performed. A method of irradiating active energy rays with a light source is preferable.
The irradiation with the active energy ray is preferably performed after a certain period of time (for example, 0.01 seconds to 120 seconds, preferably 0.01 seconds to 60 seconds) after the ink composition is landed and heat-dried. .

(Heat drying process)
When forming an image, a heating and drying step may be further provided after the applying step or after the applying step and before the irradiation step, if necessary.
In the heat drying step, the black ink applied on the substrate in the applying step is dried.

Drying can be performed using a heating means.
There is no restriction | limiting in particular in a heating means, For example, a heat drum, a warm air heater, an infrared lamp, a heat oven, a heat plate etc. can be used.
The heating temperature during drying is preferably 40 ° C. or more, more preferably about 40 ° C. to 150 ° C., and further preferably about 40 ° C. to 80 ° C.
The heating time can be appropriately set in consideration of the composition of the black ink and the film (image) formation speed.

<Light shielding film>
The light shielding film of the present disclosure is a cured product of the black ink composition for inkjet of the present disclosure described above. Therefore, it has a black color tone and a high refractive index.

The light shielding film of the present disclosure is a high refractive index film, and the refractive index is preferably 1.75 or more, and more preferably 1.80 or more.
The refractive index is a value measured by ellipsometry at a wavelength of 590 nm, and can be measured using a high-speed spectroscopic ellipsometer M-2000 (JA Woollam Japan Co., Ltd.).

The light shielding film of the present disclosure contains at least carbon black particles, titanium dioxide particles, and a basic dispersant, and may contain a curable compound and other components as necessary. The details of the components such as the carbon black particles, the titanium dioxide particles and the basic dispersant, and the curable compound and other components are as described above, and the description thereof is omitted here.
The colorant contained in the light shielding film can be arbitrarily selected from known color materials such as pigments and dyes other than carbon black and titanium dioxide.
As described above, since the black ink described above is used for the light shielding film of the present disclosure and the composition uses carbon black particles and titanium dioxide particles, the content of the colorant is preferably small. . In particular, the content of the dye is preferably less than 10% by mass, more preferably less than 1% by mass, and still more preferably less than 0.1% by mass with respect to the total mass of the light shielding film. A dye content of less than 10% by weight indicates that the composition does not contain much dye, and a dye content of less than 0.1% by weight substantially contains a dye. Indicates not.

The thickness of the light shielding film can be in the range of 0.5 μm to 20 μm, preferably in the range of 0.5 μm to 10 μm, and more preferably in the range of 0.5 μm to 5 μm.

The light-shielding film of the present disclosure can be used not only for applications that block light, but also for uses that absorb light and for applications that have a decorative function.
Especially, it is preferable that the light shielding film of this indication is used for an optical member. Details of the optical member will be described later.

<Optical member>
The optical member of the present disclosure includes a base material and the light shielding film of the present disclosure described above.
The optical member of the present disclosure includes a light-reflecting film having a high refractive index formed using the black ink composition for inkjet of the present disclosure described above, so that a difference in refractive index between the substrate and the light-shielding film is small. It is adjusted so that the reflected light can be effectively absorbed when the incident light is internally reflected in the substrate.
Since the details of the light shielding film are as described above, description thereof is omitted.

-Base material-
The substrate is not particularly limited, and any of a non-absorbing substrate that does not absorb ink and an absorbing substrate that absorbs ink can be used.
“Non-absorptive” means the water absorption rate (mass%, 24 hrs) according to ASTM D570 of ASTM test method.
. ) Indicates a property of less than 0.2.

Non-absorbable substrates include glass substrates, resin (plastic) substrates (eg, polyvinyl chloride (PVC) substrates, polystyrene (PS) substrates, polycarbonate (PC) substrates, polyester substrates (for example, Polyethylene terephthalate (PET), polyethylene naphthalate), polyolefin substrate (for example, polypropylene (PP)), acrylic resin substrate, and the like].
Examples of the absorbent substrate include paper and non-woven fabric.

The optical member of the present disclosure preferably uses a glass substrate or a resin substrate as a substrate, and has a light-shielding film on the outer peripheral surface when the thickness direction of the glass substrate or the resin substrate is taken as an axis. be able to.
Preferred examples of the optical member include a lens, a prism, and optical glass.
For example, when the optical member is a lens, for example, a glass substrate or a resin substrate is used, and a light shielding film is provided on the outer circumferential surface of the concentric circle when the thickness direction of the glass substrate or the resin substrate, that is, the light incident direction is used as an axis. is doing. In this case, when light incident obliquely into the lens hits the lens outer peripheral surface (that is, the interface between the lens and the light shielding film) before passing through the lens, it is absorbed by the light shielding film and suppresses internal reflection at the interface. can do. Thereby, generation | occurrence | production of the flare or ghost by the light which is not related to an image injects can be suppressed.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Unless otherwise specified, “part” is based on mass.

(Examples 1 to 17, Comparative Examples 1 to 7)
-Preparation of ink composition-
Each component shown in the following Tables 1 and 2 is mixed and dispersed using the beads mill NPM (manufactured by Shinmaru Enterprises Co., Ltd.) and a circulating pipe and charging tank under the following conditions. 5000 g of the ink composition having the composition shown in 2 was prepared.

<Distribution conditions>
Bead diameter: φ0.05mm
Bead filling rate: 60% by volume
Mill peripheral speed: 10 m / sec Mixing liquid amount to be dispersed: 5000 g
Circulation flow rate (pump supply amount): 30 kg / hour
Treatment liquid temperature: 25 ° C-30 ° C
Cooling water: Tap water Treatment time: 30 passes

-Membrane formation-
Using each ink composition prepared as described above, each ink was dropped on a glass substrate (Corning 1737 (manufactured by Corning), thickness 0.7 mm) and spin coating (2000 rpm (revolutions per minute)). 60 seconds). The coating film was dried in a heating furnace at 70 ° C. for 30 minutes, and ultraviolet light (wavelength 365 nm) was further applied to the dried coating film using an ultraviolet light emitting diode NC4U134 (manufactured by Nichia Corporation), 1200 mJ / cm. ^The coating film was cured by irradiation with an exposure energy amount of ² (that is, an accumulated light amount of ultraviolet light).
In this way, a light shielding film having a thickness after curing of 1.0 μm was formed.

-Evaluation-
The following measurements and evaluations were performed on the ink composition and the light-shielding film prepared as described above. The results of measurement and evaluation are shown in Tables 1 to 3. “Γ” and “bm” described in the column of organic solvent in Table 1 represent “surface tension” and “boiling point”, respectively.

(1) Refractive index of light shielding film The refractive index of the light shielding film was measured at a wavelength of 590 nm using a high-speed spectroscopic ellipsometer M-2000 (JA Woollam Japan Co., Ltd.). Evaluation was performed according to the evaluation criteria.
<Evaluation criteria>
AA: Refractive index is 1.85 or more.
A: Refractive index is 1.80 or more and less than 1.85.
B: Refractive index is 1.75 or more and less than 1.80.
C: Refractive index is less than 1.75.

(2) Light-shielding property of light-shielding film Using a desktop transmission densitometer 361T (manufactured by X-Rite) for the glass substrate on which the light-shielding film is formed, optical density at transmission (transmission OD; “OD” is from Optical Density) (Omitted) was measured. Based on the measurement results, evaluation was performed according to the following evaluation criteria.
It shows that it is excellent in light-shielding property, so that a measured value is large.
<Evaluation criteria>
AA: Transmission OD is 0.4 or more.
A: Transmission OD is 0.3 or more and less than 0.4.
B: Transmission OD is 0.1 or more and less than 0.3.
C: Transmission OD is less than 0.1.

(3) Stability over time of ink composition Each ink composition prepared as described above was allowed to stand for 7 days in an environment at a temperature of 60 ° C., and the average particle size before and after standing (particle size variation; %). The particle variation was calculated from the following formula. Then, the stability over time was evaluated according to the following evaluation criteria using the value of the particle size variation as an index.
Particle size variation (%) = (Average particle diameter after standing) / (Average particle diameter before standing) × 100
The average particle size was measured with a particle size analyzer (FPAR, manufactured by Otsuka Electronics Co., Ltd.). In the measurement, diethylene glycol diethyl ether was used as a diluting solvent for adjusting the concentration.
<Evaluation criteria>
AA: Particle variation is less than 10%.
A: Particle variation is 10% or more and less than 15%.
B: Particle variation is 15% or more and less than 20%.
C: Particle variation is 20% or more and less than 25%.

(4) Patterning property Except that the operation for forming the coating film is changed to an operation for drawing 10 line patterns, the same operation as the above “-film formation-” is performed, and the target line width is 1 mm. Ten light shielding patterns (that is, line patterns cured by ultraviolet light irradiation) were formed.
Here, the line pattern was formed by applying ink onto a glass substrate by an inkjet method using an inkjet printer DMP-3000 manufactured by FUJIFILM Corporation. At this time, the dot density was 1200 dpi × 1200 dpi, and the ink ejection amount per droplet ejected from the inkjet head was 10 pL (picoliter).

For 10 light-shielding patterns, the line widths at 10 locations per light-shielding pattern (that is, 100 locations in total) were measured, the average line width was calculated as the arithmetic average value of the obtained measurement value group, and the average obtained Based on the line width, the average fluctuation width of the line width was determined by the following formula.
Average fluctuation width of line width (%) = (Average line width−1) × 100

Based on the obtained average fluctuation range, the patterning property is evaluated according to the following evaluation criteria, and Table 3 shows the evaluation results.
In the following evaluation criteria, the rank with the highest patterning property is “A”.
<Evaluation criteria>
A: The average fluctuation range is less than 10%.
B: The average fluctuation range is 10% or more and less than 18%.
C: The average fluctuation range is 18% or more.
D: The line width cannot be measured due to ejection failure or line pattern drawing failure.

 

 

 

The detail of each component of Table 1 and Table 2 is as follows.
-Carbon black particles-
Special black 250: manufactured by Orion Engineered Carbons (furnace black; average primary particle size: 56 nm, DBP absorption: 48 ml / 100 g)
-Titania particles-
TTO-55A: manufactured by Ishihara Sangyo Co., Ltd. (rutile type; average primary particle size: 50 nm, surface treatment: Al (OH) ₃ )
R-550: manufactured by Ishihara Sangyo Co., Ltd. (rutile type; average primary particle size: 240 nm, surface treatment: Al, Si)
-Zirconia particles-
TECNAPOW-ZNO: manufactured by TECNAN (average primary particle size: 15 nm)

-Dispersant-
EFKA PX4731 manufactured by BASF (basic dispersant, amine value: 25 mgKOH / g; compound having a polyethyleneimine skeleton)
DisperBYK-168: manufactured by Big Chemie Japan Co., Ltd. (basic dispersant, amine value: 11 mgKOH / g)
solsperse 71000: manufactured by Nippon Lubrizol Co., Ltd. (basic dispersant, amine value: 78 mgKOH / g)
DisperBYK-109: manufactured by Big Chemie Japan, Inc. (basic dispersant amine value: 140 mgKOH / g)
solsperse 39000: manufactured by Nippon Lubrizol Corporation (basic dispersant, amine value: 35.7 mgKOH / g)
solsperse 36000: Nippon Lubrizol Corporation (acid dispersant)
DisperBYK-111: manufactured by Big Chemie Japan Co., Ltd. (acid dispersant)

-Curing compound-
UV-1700B: Urethane acrylate (manufactured by Nippon Synthetic Chemical Co., Ltd .; photocurable oligomer)
PEA: 2-phenoxyethyl acrylate (monofunctional photo-curable monomer)
DPGDA: Dipropylene glycol diacrylate (bifunctional photocurable monomer)
-Photopolymerization initiator-
IRG819: IRGACURE (registered trademark) 819 (manufactured by BASF; bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide))
IRG2959: IRGACURE (registered trademark) 2959 (manufactured by BASF; 2-hydroxy-4 ′-(2-hydroxyethoxy) -2-methylpropiophenone)
-Polymerization inhibitor-
MEHQ: p-methoxyphenol (manufactured by Tokyo Chemical Industry Co., Ltd.)

-Organic solvent-
DEGdEE: Diethylene glycol diethyl ether (boiling point 180 ° C., surface tension 25.0 mN / m)

As shown in Tables 1 and 2, a specific amount of titanium dioxide particles is included, carbon black particles and titanium dioxide particles are contained in a larger proportion than the carbon black particles, and basic dispersion is further included. In the examples in which the agent was selectively used, the light shielding property was good and a high refractive index was obtained. Further, the dispersion stability over time was good, and the ink jet aptitude was excellent.
In particular, compared with Example 7 in which the particle size of the titanium dioxide particles was large, in Example 1 and the like in which the particle size of the titanium dioxide particles was 100 μm or less, a higher refractive index was obtained, and the temporal stability was also excellent.
Similarly, in Example 1 using a basic dispersant having an amine value of 80 mgKOH / g or less, a higher refractive index is obtained than in Example 10 in which the amine value of the basic dispersant is high. It was excellent in terms of stability.
Furthermore, from the comparison between Example 2 and Example 12, it can be seen that the mass ratio of the content of titanium dioxide particles to the content of carbon black particles is preferably 13 or less.
Further, as shown in Table 3, in Examples 13 to 16 in which a plurality of types of organic solvents were used in combination within a certain range, better results were obtained in terms of patterning property than Example 1.

On the other hand, in the comparative example, the effect of improving the refractive index is inferior to that of the example, or the ink composition is inferior in stability over time. It has been difficult to achieve compatibility with the refractive index.

The black ink composition for inkjet according to the present disclosure is suitable for applications that require a black color tone having a high refractive index, and can also be applied to decorative applications in that it has a high refractive index. Specific examples include use of a light-shielding film for optical elements (eg, lenses, prisms, optical glass members) used in optical equipment such as cameras, binoculars, microscopes, and semiconductor exposure apparatuses, and black-based materials having surface gloss. Suitable for use as a decorative film of color tone.
Moreover, the light shielding film and the optical member of the present disclosure can be widely used for applications requiring light shielding.

The disclosures of Japanese Patent Application No. 2018-059958 filed on March 27, 2018 and Japanese Application No. 2019-023498 filed on February 13, 2019 are incorporated herein by reference in their entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

Claims (16)

1. Carbon black particles, titanium dioxide particles, and a basic dispersant,
   The content of the titanium dioxide particles is 15% by mass or more and 45% by mass or less with respect to the total mass of the composition,
   A black ink composition for inkjet, wherein a mass ratio of the content of the titanium dioxide particles to the content of the carbon black particles is 2.0 or more and 15.0 or less.
2. 2. The black ink composition for inkjet according to claim 1, wherein the basic dispersant has an amine value of 10 mgKOH / g or more and 80 mgKOH / g or less.
3. 3. The black ink composition for inkjet according to claim 1, wherein the titanium dioxide particles have an average primary particle diameter of 10 nm to 100 nm.
4. The black ink composition for inkjet according to any one of claims 1 to 3, wherein a content of the carbon black particles is from 1% by mass to 6% by mass with respect to a total mass of the composition.
5. The black ink composition for inkjet according to any one of claims 1 to 4, further comprising an organic solvent having a boiling point of 120 ° C or higher.
6. The black ink composition for inkjet according to claim 5, wherein the content of the organic solvent is 10% by mass or more and 55% by mass or less with respect to the total mass of the composition.
7. Containing at least two organic solvents having a boiling point of 120 ° C. or higher;
   Of the organic solvents having a boiling point of 120 ° C. or higher, when the boiling point of one organic solvent is BPa and the boiling point of the other organic solvent is BPb, the relationship of 120 ° C. <BPa <BPb <250 ° C. is satisfied. ,
   And,
   Of the organic solvents having a boiling point of 120 ° C. or higher, the surface tension of one organic solvent in units of mN / m is γa, and the surface tension of the other organic solvent in units of mN / m is When γb is satisfied, the relationship of γa <γb is satisfied.
   The black ink composition for ink jet according to claim 5 or 6.
8. The black ink composition for inkjet according to claim 7, wherein the γa and the γb satisfy a relationship represented by γa <30 mN / m <γb.
9. The black ink composition for inkjet according to any one of claims 1 to 8, further comprising at least one curable compound selected from a photocurable monomer and a photocurable resin.
10. A light-shielding film, which is a cured product of the black ink composition for ink jet according to any one of claims 1 to 9.
11. The light-shielding film according to claim 10, having a refractive index of 1.75 or more.
12. The light-shielding film according to claim 10 or 11, wherein the dye content is less than 10% by mass.
13. 13. The light-shielding film according to claim 10, which is used for an optical member.
14. A substrate;
    The light-shielding film according to any one of claims 10 to 13,
    An optical member comprising:
15. The substrate is a glass substrate or a resin substrate;
    The optical member of Claim 14 which has the said light shielding film in the outer peripheral surface at the time of setting the thickness direction of the said glass base material or the said resin base material as an axis | shaft.
16. 10. An image forming method comprising a step of applying the black ink composition for ink jet according to any one of claims 1 to 9 on a substrate by an ink jet method.