JP2012092251A - Oil-based ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil-based ink composition that is excellent in pigment dispersibility and dispersion stability of diketopyrrolopyrrole being a red pigment and is suitable for writing utensils for marking and the like.SOLUTION: The oil-based ink composition contains at least: a pigment derivative obtained by adding a water-soluble dye to an acid solution and subjecting the resultant mixture to insolubilization, wherein the water-soluble dye has an azo bond and contains sodium sulfonate in its structure as a functional group, and is selected at least from red, yellow, orange and purple; a basic pigment dispersant; an organic pigment diketopyrrolopyrrole; an organic solvent having a boiling point of <150°C; and an immobilized resin.

Description

  The present invention relates to an oil-based ink composition containing diketopyrrolopyrrole, which is a red pigment, and more specifically, for a writing instrument such as a marking, which is excellent in pigment dispersibility and dispersion stability of diketopyrrolopyrrole, which is a red pigment. The present invention relates to a suitable oil-based ink composition.

Conventionally, when an organic pigment is dispersed with a dispersant, the dispersant is hardly adsorbed on the surface of the organic pigment and is generally difficult to disperse. Therefore, a method is generally used in which a pigment derivative that becomes a substance adsorbing with a dispersant is produced and interacts with the surface of the organic pigment.
The interaction between the pigment derivative and the dispersant is usually an acid-base reaction, and the adsorption of the pigment derivative and the organic pigment is generally said to be an interaction between aromatic systems.
Among organic pigments, when a red pigment, particularly a diketopyrrolopyrrole pigment is used, there is a problem that the dispersant is difficult to adsorb on the surface of the organic pigment.

In order to improve the dispersion performance of organic pigments such as diketopyrrolopyrrole in organic solvents, etc., functional groups have been introduced into pigments, commercially available pigment derivatives have been used together, or newly synthesized pigment derivatives, etc. Attempts have been made to disperse these in combination.
For example, 1) a novel pigment derivative containing a pyrazole group (see, for example, Patent Document 1), 2) a colorant, a pigment derivative having a sulfone group, a dispersant, and benzyl alcohol, an ink for oil-based ballpoint pens Composition (see, for example, Patent Document 2), 3) Pigment, specific acidic functional group-containing organic dye derivative, alkali-soluble resin having specific physical properties having amino group and / or quaternary ammonium salt thereof, and organic solvent 4) At least an organic pigment, the organic pigment and / or a pigment having a chemical structure identical to a part of the chemical structure of the organic pigment has a sulfonic acid group An ink comprising: an introduced pigment derivative; a polymer dispersant containing an amino group-containing side chain, a hydrophilic side chain, and a hydrophobic side chain; and water 5) In a pigment dispersion composition comprising an organic pigment, an organic solvent, and a finely dispersed component, the finely dispersed component is an acidic derivative of the organic pigment and a cation in the trunk polymer portion. A pigment dispersion composition comprising a cationic comb-shaped graft polymer having a functional functional group (see, for example, Patent Document 5), 6) a red color obtained by dispersing a red pigment in a photosensitive resin composition In the color resist ink, diketopyrrolopyrrole is dispersed as a red pigment, and 4,4′-diamino-1,1′-bianthraquinone-3,3′-disulfonic acid is dispersed as an essential component as a pigment derivative. A red color resist ink (see, for example, Patent Document 6) is known.

  However, each of the techniques described in Patent Documents 1 to 6 has a complicated manufacturing process for obtaining a pigment derivative, or has a problem of danger because fuming sulfuric acid is used to introduce a sulfone group. Even in the case of using other pigment derivatives, there is a problem that the stability of the obtained pigment dispersion is still insufficient.

JP-A-4-285669 (Claims, Examples, etc.) Japanese Unexamined Patent Publication No. 2000-212696 (Claims, Examples, etc.) JP 2007-84659 A (Claims, Examples, etc.) Japanese Patent Laying-Open No. 2005-2186 (Claims, Examples, etc.) JP-A-9-176511 (Claims, Examples, etc.) JP 2000-19725 (Claims, Examples, etc.)

  The present invention has been made in view of the above-described problems of the prior art and the current situation, and is intended to solve this problem. For writing instruments such as markings excellent in pigment dispersibility and dispersion stability of diketopyrrolopyrrole, which is a red pigment. An object is to provide a suitable oil-based ink composition.

  As a result of intensive studies in view of the above-described conventional problems, the present inventors have found that at least a water-soluble dye selected from at least red, yellow, orange, and purple contained as a specific functional group in the structure in an acidic solution. By adding a pigment derivative obtained by adding and insolubilizing, a basic pigment dispersant, an organic pigment diketopyrrolopyrrole, an organic solvent having specific physical properties, and a fixing resin, the above-described oil-based ink composition It was found that a product was obtained, and the present invention was completed.

That is, the present invention resides in the following (1) to (6).
(1) A pigment derivative obtained by insolubilizing at least a water-soluble dye selected from red, yellow, orange and purple containing at least an azo bond and sodium sulfonate as a functional group in the structure, and a base; An oil-based ink composition characterized by comprising an organic pigment dispersant, an organic pigment diketopyrrolopyrrole, an organic solvent having a boiling point of less than 150 ° C., and a fixing resin.
(2) The oil-based ink composition according to the above (1), wherein the water-soluble dye is an acid dye, a direct dye or a mordant dye.
(3) The oil-based ink composition according to the above (1), wherein the water-soluble dye is an acid dye.
(4) The oil-based ink composition according to any one of (1) to (3), wherein the water-soluble dye is at least one selected from Acid Orange 7, Acid Orange 8, Acid Orange 20, and Acid Red 88. .
(5) The oil-based ink composition according to any one of (1) to (4), wherein the organic solvent is propylene glycol monomethyl ether.
(6) The oil-based ink composition according to any one of (1) to (5), wherein the ink viscosity is in the range of 2.0 to 10.0 mPa · s at 25.0 ° C.

  ADVANTAGE OF THE INVENTION According to this invention, the oil-based ink composition suitable for writing instruments, such as a marking thing excellent in the pigment dispersibility and dispersion stability of the diketopyrrolopyrrole which is a red pigment, is provided.

Hereinafter, embodiments of the present invention will be described in detail.
The oil-based ink composition of the present invention is obtained by insolubilizing at least a water-soluble dye selected from red, yellow, orange and purple containing at least an azo bond and sodium sulfonate as a functional group in the structure. And a basic pigment dispersant, an organic pigment diketopyrrolopyrrole, an organic solvent having a boiling point of less than 150 ° C., and a fixing resin.

As the pigment derivative of the present invention, a pigment derivative obtained by insolubilizing at least a water-soluble dye selected from red, yellow, orange and purple containing azo bond and sodium sulfonate as a functional group in the structure is used. It can be easily obtained by adding a water-soluble dye having the above characteristics to an acidic solution to make it insoluble in water.
The water-soluble dye to be used is not particularly limited as long as it is a dye having an azo bond and sodium sulfonate as a functional group in the structure, but is preferably an acid dye because a dye is precipitated by adding an acidic substance to an aqueous dye solution. Direct dyes or mordant dyes are preferred, and acid dyes are particularly preferred.
In addition, since the diketopyrrolopyrrole pigment used is red or orange, usable dyes are limited to yellow, red, orange, and purple. When black or blue dyes having colors other than these are used, the color of the ink is dull, which is not preferable.

Examples of the orange water-soluble acid dye include Acid Orange 1, Acid Orange 10, Acid Orange 7, Acid Orange 8, Acid Orange 19, Acid Orange 20, Acid Orange 24, Acid Orange 28, Acid Orange 33, and Acid Orange 41. , Acid Orange 45, Acid Orange 51, Acid Orange 56, and Acid Orange 74.
Examples of the purple water-soluble acid dye include those selected from Acid Violet 7 and Acid Violet 11.
Examples of red water-soluble acid dyes include Acid Red 1, Acid Red 6, Acid Red 88, Acid Red 8, Acid Red 9, Acid Red 13, Acid Red 14, Acid Red 18, Acid Red 26, and Acid Red 27. Acid Red 32, Acid Red 35, Acid Red 37, Acid Red 42, Acid Red 52, Acid Red 80, Acid Red 82, Acid Red 83, Acid Red 85, Acid Red 88, Acid Red 89, Acid Red 97, Acid Red 106, Acid Red 111, Acid Red 114, Acid Red 115, Acid Red 133, Acid Red 134, Acid Red 145, Acid Red 154, Acid Red 155 Acid Red 158, Acid Red 180, Acid Red 183, Acid Red 184, Acid Red 186, Acid Red 198, Acid Red 249, includes one selected from Acid Red 265.
Examples of yellow water-soluble acid dyes include Acid Yellow 11, Acid Yellow 17, Acid Yellow 23, Acid Yellow 25, Acid Yellow 29, Acid Yellow 36 Acid Yellow 38, Acid Yellow 40, Acid Yellow 42, Acid Yellow 44, Examples include acid yellow 76 and acid yellow 98 acid yellow 99.
Examples of the orange water-soluble direct dye include direct orange 6, direct orange 8, direct orange 10, direct orange 26, direct orange 29, direct orange 39, direct orange 41, direct orange 49, and direct orange 102. The ones that are chosen are listed.
An example of a purple water-soluble direct dye is direct violet 63.
Examples of red water-soluble direct dyes are Direct Red 1, Direct Red 2, Direct Red 4, Direct Red 13, Direct Red 17, Direct Red 20, Direct Red 21, Direct Red 24, Direct Red 28, Direct Red. 31, Direct Red 33, Direct Red 37, Direct Red 39, Direct Red 44, Direct Red 46, Direct Red 62, Direct Red 63, Direct Red 75, Direct Red 79, Direct Red 80, Direct Red 81, Examples thereof include those selected from direct red 83, direct red 84, direct red 113, and direct red 229.
Examples of the yellow water-soluble direct dye include direct yellow 8, direct yellow 11, direct yellow 12, direct yellow 24, direct yellow 27, direct yellow 28, direct yellow 33, direct yellow 39, direct yellow 44, and direct yellow 50. The thing chosen from is mentioned.
Examples of the orange water-soluble mordant dye include those selected from Modern Orange 4, Modern Orange 6, Modern Orange 29, and Modern Orange 37.
Examples of the purple water-soluble mordant dye include those selected from Modern Violet 5 and Modern Violet 44.
Examples of the red water-soluble mordant dye include those selected from the modern tread 3, the modern tread 7, the modern tread 9, the modern tread 17, the modern tread 19, the modern tread 21, the modern tread 26, and the modern tread 30.
Examples of the yellow water-soluble mordant dye include those selected from Modern Yellow 3 and Modern Yellow 26.
Among these water-soluble acid dyes, water-soluble direct dyes, and water-soluble mordant dyes, from the viewpoint of dispersibility and stability of the diketopyrrolopyrrole pigment, Acid Orange 7, Acid Orange 8, Acid Orange 20, It is desirable to use Acid Red 88, Direct Red 2, and Modern Orange 37, and more preferably, one selected from Acid Orange 7, Acid Orange 8, Acid Orange 20, and Acid Red 88.

The acidic solution which can be used is not specifically limited, For example, hydrochloric acid aqueous solution, sulfuric acid aqueous solution, acetic acid aqueous solution, nitric acid aqueous solution etc. are mentioned. The concentration of these acidic solutions is, for example, about 0.2 to 5.0 N when the addition amount of the water-soluble dye is 10%.
In the pigment derivative of the present invention, for example, when the water-soluble dye is added to the acidic solution and stirred, the sodium atom of sodium sulfonate (SO ₃ Na) in the water-soluble dye structure is replaced with a hydrogen atom. To sulfonic acid (SO ₃ H). Since it becomes insoluble in water at this time, it can be recovered as each pigment derivative by filtration, drying or the like. Alternatively, a pigment derivative may be obtained by dissolving a water-soluble dye in water and adding an acidic solution to the resulting aqueous dye solution to cause precipitation.
For example, in order to obtain a pigment derivative using Acid Orange 7, sodium 7,4-[(2-hydroxynaphthalen-1-yl) azo] benzenesulfonate, which is Acid Orange 7, is purified at room temperature or the like. After dissolution, the hydrochloric acid solution is added to form a precipitate as 7,4-[(2-hydroxynaphthalen-1-yl) azo] benzenesulfonic acid, and then the desired pigment is obtained by suction filtration, vacuum drying, etc. Derivatives can be obtained.

The content of these pigment derivatives is preferably 0.1 to 5.0%, more preferably 0.00% in the total amount of the oil-based ink composition (100% by mass, simply “% by mass” is referred to as “%”). It is desirable to be 2 to 2.0%.
When the content of the pigment derivative is less than 0.1%, the dispersibility of the pigment becomes insufficient. On the other hand, when the content exceeds 5%, the water resistance and light resistance of the coating film deteriorate, and the ink viscosity increases. Therefore, it is not preferable.

The diketopyrrolopyrrole that is a red pigment used in the present invention is not particularly limited as long as it is used as a diketopyrrolopyrrole pigment. For example, Pigment Orange 71, Pigment Orange 73, Pigment Orange 81, Pigment Red 254, Pigment Red 255, Pigment Red 264, and Pigment Red 270 can be used. Commercially available products include diketopyrrolopyrrole BTR (manufactured by BASF), Irgadine 2030 (manufactured by BASF), and chromoftal flame red FP. (BASF), B-CF (BASF) BT-CF (BASF).
The content of these diketopyrrolopyrrole pigments is preferably 2 to 15%, more preferably 4 to 10% in the total amount of the oil-based ink composition.
When the content of the diketopyrrolopyrrole pigment is less than 2%, a light red coating film is formed. On the other hand, when the content exceeds 15%, the ink fixing property is lowered, which is not preferable.

The pigment dispersant used in the present invention is limited to a basic pigment dispersant. This is because the sulfonic acid in the pigment derivative interacts with the base in the dispersant to develop dispersibility.
The basic pigment dispersant to be used is not particularly limited as long as it is classified as a basic pigment dispersant. For example, a basic polymer dispersant such as a polyamidoamine and a salt thereof, a basic functional group. Examples thereof include at least one of modified polyurethane, basic functional group-modified polyester, basic functional group-modified poly (meth) acrylate, polyoxyethylene alkylamine, alkanolamine, and polyacrylamide.
Specifically, commercially available Sol Sparse 11200, Sol Sparse 13240, Sol Sparse 13650, Sol Sparse 13940, Sol Sparse 16000, Sol Sparse 17000, Sol Sparse 18000, Sol Sparse 20000, Sol Sparse 24000SC, Sol Sparse 24000GR, Sol Sparse 26000, Sol Sparse 28000, Sol Sparse 31845, Sol Sparse 32000, Sol Sparse 32000, 32500, Sol Sparse 32550, Sol Sparse 32600, Sol Sparse 33000, Sol Sparse 34750, Sol Sparse 35100, Sol Sparse 35200, Sol Sparse 37500, Sol Sparse 38500, Sol Sparse 39000, Sol Sparse 53005, Sol Sparse 56000, Sol Sparse 71000 (Above, Solsperse series Lubrizol), Dispersic 161, Dispersic 162, Dispersic 163, Dispersic 164, Dispersic 166, Dispersic 167, Dispersic 168 (above, Dispersic series manufactured by BYK Chemie), At least one of Ajisper PB821, Ajisper PB822, Azisper PB881 (more from Ajisper series Ajinomoto Fine Techno Co., Ltd.), Naimine DT208, Naimine L208, Naimine S125, Naimine S210, Naimine O205 (more from Naimine series Nippon Oil & Fats) Can be mentioned.
The content of these basic pigment dispersants is preferably 1 to 10%, more preferably 2 to 6% in the total amount of the oil-based ink composition.
When the content of the basic pigment dispersant is less than 1%, the dispersibility of the pigment becomes insufficient. On the other hand, when the content exceeds 10%, the fixability of the ink coating film becomes insufficient.

The fixing resin used in the present invention is not particularly limited as long as it can be dissolved in an organic solvent having a boiling point below 150 ° C., for example, alkylphenol, terpene phenol, ketone resin, xylene resin, acrylic resin, styrene acrylic. Examples thereof include at least one of acid resin, polyvinyl butyral, vinyl chloride resin, epoxy resin, polyurethane resin, polyamide resin, polyester resin, polyether resin, and melamine resin.
The content of these fixing resins (solid content) is preferably 2 to 20%, more preferably 4 to 15% in the total amount of the oil-based ink composition from the viewpoint that the ink is dried to form a coating film. It is desirable. Further, from the viewpoint of ink viscosity, the organic solvent: fixing resin content ratio on a mass basis, preferably 20: 1 to 2: 1, more preferably 10: 1 to 5: with respect to the organic solvent described later. 1 is desirable.

The organic solvent used in the present invention is not particularly limited as long as the boiling point is less than 150 ° C., preferably 60 ° C. or more and less than 150 ° C. For example, methanol, ethanol, propylene glycol monomethyl ether, isopropyl alcohol, normal propanol , At least one of lower alcohols such as propylene glycol monoethyl ether, esters such as propylene glycol monomethyl ether acetate, ethyl acetate and butyl acetate, nitrogen-containing solvents, acetones, toluene, xylene, isooctane and methylcyclohexane Preferably, use of propylene glycol monomethyl ether is desirable from the viewpoint of drying and filling a plastic marking pen container.
The content of these organic solvents is preferably 60 to 95%, more preferably 70 to 90% in the total amount of the oil-based ink composition.
When the content of the organic solvent is less than 60%, the ink viscosity increases. On the other hand, when the content exceeds 95%, the amount of the colorant and the fixing resin becomes insufficient, the color becomes faint, and the coating film is fixed. It is not preferable because the sex becomes weak.

  In the oil-based ink composition of the present invention, in addition to the above components, various optional components such as titanium oxide and complementary color pigments are used in accordance with the use of the oil-based ink composition as long as the effects of the present invention are not impaired. , A polymer dispersant, a surface tension adjuster, an evaporation inhibitor, a peeling agent, a plasticizer, a non-volatile solvent and the like can be appropriately contained.

The oil-based ink composition of the present invention is obtained by mixing and dispersing the pigment derivative, the basic pigment dispersant, the organic pigment diketopyrrolopyrrole and an organic solvent having a boiling point of less than 150 ° C. using a mixer or the like. Thereafter, the target oil-based ink composition can be obtained by mixing and dispersing the dispersion and the fixing resin.
The ink viscosity of the obtained oil-based ink composition is preferably in the range of 2.0 to 10.0 mPa · s at 25.0 ° C., from the viewpoint of discharging the ink satisfactorily from the pen tip. .
The ink viscosity can be adjusted to a suitable ink viscosity by combining the above components with a suitable content.

In the oil-based ink composition of the present invention configured as described above, at least a water-soluble dye selected from red, yellow, orange and purple containing at least an azo bond and sodium sulfonate as a functional group in the structure is added to the acidic solution. For the first time by containing a pigment derivative obtained by insolubilization, a basic pigment dispersant, an organic pigment diketopyrrolopyrrole, an organic solvent having a boiling point of less than 150 ° C., and a fixing resin. The pyrrole pigment can be finely dispersed in an organic solvent while maintaining good stability, and an oil-based ink composition excellent in pigment dispersibility and dispersion stability of diketopyrrolopyrrole, which is a red pigment. It will be obtained.
In the oil-based ink composition of the present invention, the above-mentioned red pigment, diketopyrrolopyrrole, is excellent in pigment dispersibility and dispersion stability, so it can be used for writing pens such as marking pens and paint markers, and whiteboard markers. In particular, since the diketopyrrolopyrrole pigment is excellent in light resistance, it is excellent in light resistance compared to conventional dye inks and can be suitably used for writing instruments such as marking pens.

  EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to the following Example etc.

[Examples 1-5 and Comparative Examples 1-5]
Example 1
10 g of Acid Orange 7, which is a water-soluble acid dye, was dissolved in 1000 g of purified water, and 20 g of 5N hydrochloric acid was added to generate a precipitate. This was suction filtered with an aspirator and dried in vacuum at room temperature for 48 hours to obtain 9.8 g of pigment derivative (1).
Next, 20 g of diketopyrrolopyrrole BTR, 2.0 g of pigment derivative (1), 10 g of basic pigment dispersant: Solsperse 71000, and 168 g of organic solvent: propylene glycol monomethyl ether (boiling point: 120 ° C., the same applies below) are mixed. A slurry was prepared. This slurry was dispersed using a wet disperser dyno mill under the conditions of a zirconia bead having a diameter of 0.3 mm and a filling rate of 70% to obtain a dispersion.
The obtained dispersion and terpene phenol G150, which is a fixing resin, were mixed at a ratio of 9: 1 to dissolve the resin, thereby obtaining an oil-based ink composition (1).
The content of each component in this oil-based ink composition (1) is 0.9% by mass of the pigment derivative, 4.5% by mass of the basic pigment dispersant, and the organic pigment diketopyrrolopyrrole 9 in the total amount (100% by mass). Mass%, organic solvent 75.6 mass%, fixing resin 10 mass%.

(Example 2)
10 g of Acid Orange 8, which is a water-soluble acid dye, was dissolved in 1000 g of purified water, and 20 g of 5N hydrochloric acid was added to generate a precipitate. This was suction filtered with an aspirator and dried to obtain 9.7 g of a pigment derivative (2).
Next, 20 g of Irgazine 2030, which is diketopyrrolopyrrole, 2.0 g of pigment derivative (2), 10 g of basic pigment dispersant: Solsperse 71000, and 168 g of propylene glycol monomethyl ether were mixed to prepare a slurry. This slurry was dispersed using a wet disperser dyno mill under the conditions of a zirconia bead having a diameter of 0.3 mm and a filling rate of 70% to obtain a dispersion.
The obtained dispersion liquid and terpene phenol G150, which is a fixing resin, were mixed at a ratio of 9: 1 to dissolve the resin to obtain oil-based ink (2).
The content of each component in the oil-based ink composition (2) is 0.9% by mass of the pigment derivative, 4.5% by mass of the basic pigment dispersant, and the organic pigment diketopyrrolopyrrole 9 in the total amount (100% by mass). Mass%, organic solvent 75.6 mass%, fixing resin 10 mass%.

(Example 3)
10 g of acid orange 20 which is a water-soluble acid dye was dissolved in 1000 g of purified water, and 20 g of 5N hydrochloric acid was added to generate a precipitate. This was suction filtered with an aspirator and dried to obtain 9.7 g of a pigment derivative (2).
Next, 20 g of diketopyrrolopyrrole chromoftal flame red FP, 2.0 g of pigment derivative (2), basic pigment dispersant: 10 g of Solsperse 71000, and 168 g of propylene glycol monomethyl ether are mixed to prepare a slurry. did. This slurry was dispersed using a wet disperser dyno mill under the conditions of a zirconia bead having a diameter of 0.3 mm and a filling rate of 70% to obtain a dispersion.
The obtained dispersion and resin SK, which is a ketone resin, which is a fixing resin, were mixed at a ratio of 9: 1, and the resin was dissolved to obtain an oil-based ink (3).
The content of each component in the oil-based ink composition (3) is 0.9% by mass of the pigment derivative, 4.5% by mass of the basic pigment dispersant, and the organic pigment diketopyrrolopyrrole 9 in the total amount (100% by mass). Mass%, organic solvent 75.6 mass%, fixing resin 10 mass%.

Example 4
10 g of Acid Red 88, which is an acid dye, was dissolved in 1000 g of purified water, and 20 g of 5N hydrochloric acid was added to generate a precipitate. This was subjected to suction filtration with an aspirator and dried to obtain 9.7 g of a pigment derivative (4).
Next, 20 g of diketopyrrolopyrrole chromoftal flame red FP, 2.0 g of pigment derivative (4), 10 g of basic pigment dispersant: Solsperse 71000, 100 g of propylene glycol monomethyl ether, and 68 g of ethanol are mixed. A slurry was created. This slurry was dispersed using a wet disperser dyno mill under the conditions of a zirconia bead having a diameter of 0.3 mm and a filling rate of 70% to obtain a dispersion.
The obtained dispersion and terpene phenol S145, which is a fixing resin, were mixed at a ratio of 9: 1 to dissolve the resin to obtain oil-based ink (4).
The content of each component in the oil-based ink composition (4) is 0.9% by mass of the pigment derivative, 4.5% by mass of the basic pigment dispersant, and the organic pigment diketopyrrolopyrrole 9 in the total amount (100% by mass). Mass%, organic solvent 75.6 mass%, fixing resin 10 mass%.

(Example 5)
10 g of direct red 2, which is a water-soluble direct dye, was dissolved in 1000 g of purified water, and 20 g of 5N hydrochloric acid was added to generate a precipitate. This was suction filtered with an aspirator and dried to obtain 9.7 g of a pigment derivative (5).
Next, 20 g of diketopyrrolopyrrole chromoftal flame red FP, 2.0 g of pigment derivative (5), basic pigment dispersant: 10 g of Solsperse 71000, and 168 g of propylene glycol monomethyl ether are mixed to prepare a slurry. did. This slurry was dispersed using a wet disperser dyno mill under the conditions of a zirconia bead having a diameter of 0.3 mm and a filling rate of 70% to obtain a dispersion.
The obtained dispersion was mixed with a 9: 1 ratio of alkylphenol, which is a fixing resin, in a ratio of 9: 1 to dissolve the resin to obtain an oil-based ink (5).
The content of each component in this oil-based ink composition (5) is 0.9% by mass of the pigment derivative, 4.5% by mass of the basic pigment dispersant, and the organic pigment diketopyrrolopyrrole 9 in the total amount (100% by mass). Mass%, organic solvent 75.6 mass%, fixing resin 10 mass%.

(Comparative Example 1)
An oil-based ink (6) was obtained by the formulation of Example 1 and a formulation that did not contain a pigment derivative. In addition, content (0.9%) of the pigment derivative which is not used was added as the amount of organic solvents.

(Comparative Example 2)
The pigment derivative (same amount) with the formulation of Example 1 was formulated with a commercially available pigment derivative Solsperse 22000 (water-insoluble dye insoluble in both water and alkaline water) to obtain an oil-based ink (7).

(Comparative Example 3)
In the formulation of Example 1 above, Acid Orange 7 (same amount) was formulated into the formulation without being processed as it was to obtain oil-based ink (8).

(Comparative Example 4)
The organic pigment diketopyrrolopyrrole (same amount) in the formulation of Example 1 was changed to Pigment Pigment Red 48: 1 having a different structure to obtain an oil-based ink (9).

(Comparative Example 5)
In the formulation of Example 1, the basic dispersant (same amount) was changed to Joncrill 690, which is a styrene acrylic resin, which is an acidic dispersant, to obtain an oil-based ink (10).

The oil-based ink compositions obtained in the above Examples and Comparative Examples were obtained in order to evaluate the average particle diameter of the pigment in the ink, the ink viscosity, and the stability of the ink by the following measurement method as the ink physical properties. The obtained ink was stored at 50 ° C. for 1 week, and the particle size and viscosity were measured again.
These results are shown in Table 1 below.

(Measurement method of average particle diameter of pigment in ink)
The average particle diameter of the pigment in the ink was measured at 25 ° C. by diluting with propylene glycol monomethyl ether using N4 plus manufactured by Coulter.
(Measurement method of ink viscosity)
The viscosity of the ink was measured at 25 ° C. at 50 rpm or 20 rpm with an E-type viscometer TVE20 manufactured by Toki Sangyo Co., Ltd.
(Evaluation method of ink stability)
Each oil-based ink composition obtained was stored at 50 ° C. for 1 week, and then the average particle size of the pigment in the ink and the ink viscosity were measured once again by the above-described methods.

As is clear from the results of Table 1 above, Examples 1 to 5, which are the scope of the present invention, are compared with Comparative Examples 1 to 5 which are outside the scope of the present invention, and the average particle diameter of the pigment in the ink and the ink viscosity Was found to have an ink composition capable of exhibiting the effects of the present invention, excellent in ink stability over time, and excellent in pigment dispersibility and dispersion stability of the desired red pigment, diketopyrrolopyrrole.
Moreover, when filling the obtained oil-based ink composition of Examples 1-5 into the batting type | mold marking pen A-50E by Mitsubishi Pencil Co., Ltd. and writing on paper and glass, with respect to writing on both paper and glass Both were excellent in color development and writing performance.

  An oil-based ink composition suitable for a writing instrument such as a marking pen can be obtained.

Claims (6)

  At least a pigment derivative obtained by insolubilizing an acidic solution by adding at least a water-soluble dye selected from red, yellow, orange and purple containing azo bond and sodium sulfonate as a functional group in the structure, and basic pigment dispersion An oil-based ink composition comprising an agent, an organic pigment diketopyrrolopyrrole, an organic solvent having a boiling point of less than 150 ° C., and a fixing resin.   The oil-based ink composition according to claim 1, wherein the water-soluble dye is an acid dye, a direct dye or a mordant dye.   The oil-based ink composition according to claim 1, wherein the water-soluble dye is an acid dye.   The oil-based ink composition according to any one of claims 1 to 3, wherein the water-soluble dye is at least one selected from Acid Orange 7, Acid Orange 8, Acid Orange 20, and Acid Red 88.   The oil-based ink composition according to any one of claims 1 to 4, wherein the organic solvent is propylene glycol monomethyl ether.   The oil-based ink composition according to any one of claims 1 to 5, wherein the ink viscosity is in a range of 2.0 to 10.0 mPa · s at 25.0 ° C.