JPH08176463A - Carbon black for printing ink - Google Patents

Abstract

PURPOSE: To obtain a carbon black for printing inks, having bluishness and a high degree of blackness and excellent dispersibility. CONSTITUTION: This carbon black has a relative tinting strength of 80-115%, a nitrogen adsorption specific surface area of 50-100m/g, a DBP absorption of 60-100ml/100g, a modal diameter (Dmod ) of agglomerates of 140-230nm as determined by the centrifugal sedimentation method, a content of 25μm or larger coarse particles of 50ppm or below, and an ash content of 0.25% or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a black pigment for a printing ink, and more particularly to a carbon black for a printing ink having a bluish color and a high jet blackness and excellent dispersibility.

[0002]

2. Description of the Related Art When carbon black is used for printing ink, it is required to have excellent hue such as blackness and blue tint, fluidity of ink and dispersibility in an ink vehicle. In other words, the performance of carbon black generally required for lithographic offset inks, etc., must be sufficient jet black and bluish color tone, and the fluidity should not be impaired even when it is blended in a high amount when kneaded into an ink vehicle.

Therefore, in order to obtain a carbon black having a color tone suitable for ink, it is necessary to select, for example, the specific surface area and the DBP oil absorption. The applicant of the present invention has recently found that the specific coloring power is 80 to 115%, the nitrogen adsorption specific surface area is 50 to 100 m ² / g, and the DBP oil absorption is 60 to 10%.
It was found that 0 ml / 100 g and an aggregate diameter (D _mod ) of 140 to 230 nm obtained by the centrifugal sedimentation method have a hue suitable as carbon black for ink applications (Japanese Patent Application No. 5-162702).

[0004]

However, carbon black satisfying these four requirements can satisfy bluish, jet-black feeling and ink fluidity, but it is a problem to achieve good dispersibility in the ink vehicle. was there.

[0005]

As described above, the carbon black of the present invention must maintain the balance of the specific coloring power, the adsorption specific surface area of nitrogen, the DBP oil absorption, and the aggregate diameter (D _mod ) by the centrifugal sedimentation method. In addition to having a coarse particle content of 25 μm or more and an ash content within a specific range, which is obtained according to the test method described later, it has a bluish color tone, jet blackness, ink good flowability, and dispersion in an ink vehicle. Carbon black having good properties can be obtained. Incidentally, the coarse-grain fraction referred to in the present invention is a carbide of carbon, which is usually called grit.

Especially, the coarse particles of 25 μm or more are 50 ppm.
Below, it is preferably selected from 30 ppm or less and the ash content is 0.25% or less, preferably 0.20% or less. When the content of coarse particles is more than the above range, the compatibility with the ink vehicle becomes poor, and the coarse particles remain in the ink as they are, resulting in poor dispersibility. On the other hand, when the ash content is larger than the above range, the alkali in the ash functions as a coagulant for the carbon black, making it difficult for the carbon black to unravel and degrading the dispersibility. In order to obtain the coarse-grain carbon black and low ash carbon black of the present invention, for example, a two-fluid burner having a wide spray angle is used as a raw oil spray burner. It is manufactured at relatively high temperature. The carbon black of the intended quality can be obtained by manufacturing by paying attention to the point of suppressing the addition rate of alkali.

For example, as shown in FIG. 1, use is made of a type having one feed oil supply burner 1 and a plurality of combustion burners 2 on the bottom of the furnace, and recovering carbon black produced from the upper part. You can For example, as a raw oil burner, the spray angle is 60 ° or more, preferably 8
A two-fluid burner from 0 ° to 150 ° can be used. As the structure of the burner, generally, as shown in FIG. 3, a structure having a collision plate 3 at the tip of the spray of the raw material oil can be mentioned.

As for the decomposition, the decomposition is carried out at 1300 to 1500 ° C., preferably 1350 to 1400 ° C. As the alkali additive, for example, potassium carbonate is typical, but the amount used is usually 500 ppm or less, preferably 200 to 400 ppm, relative to the feed oil.
If it is a small amount, it is possible to obtain a material suitable for ink having a small amount of ash.

[0009]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the description of these examples as long as the gist thereof is not exceeded. Examples 1 to 3 Table 1 shows the characteristic values of the carbon blacks obtained in Reference Examples 1 to 3 described later as Examples 1 to 3. An ink was prepared by using these carbon blacks according to the test method (7) (a), and the ink suitability was tested. Table 1 shows the results.

Comparative Examples 1 to 3 Table 1 shows the characteristic values of the carbon blacks obtained in Reference Examples 4 to 6 described later as Comparative Examples 1 to 3. Inks were prepared using these carbon blacks in the same manner as in Examples 1 to 3 and tested for ink suitability. Table 1 shows the results. As is clear from Table 1, Examples 1 to 3 maintain the same bluish color tone, jet blackness and fluidity as Comparative Examples 1 and 2, and the dispersibility is obviously superior to Comparative Examples 1 and 2. I understand. Comparative Example 3 also has excellent dispersibility, but the aggregate diameter (D _mod ) is out of the scope of the claims of the present invention, and thus it can be seen that the balance between blackness and bluish color tone is poor. That is, Examples 1 to 3 have specific coloring power, nitrogen adsorption specific surface area, D
Since the BP oil absorption and the aggregate diameter are at the same level as Comparative Examples 1 and 2, and the coarse particles and ash content of 25 μm or more are sufficiently small,
It can be said that it has a bluish color tone, a high jet black feeling, good fluidity, and excellent dispersibility.

Reference Examples 1 to 3 (Production Example) Using a vertical furnace (FIG. 1) having a cylindrical reactor, 300 kg / H of fuel oil (2) was atomized with air of 150 Nm ³ /.
Introduced from the lower part of the furnace together with H and combustion air of 4500 Nm ³ / H and burned, potassium carbonate 400 to 1000 p
Raw oil (1) containing pm (C / H ratio 14.7, BMCI
Creosote oil having a value of 158) from the center of the lower part of the furnace at a spray pressure of 6 kg / cm ² using a two-fluid burner having a collision plate (3) at the spray tip as shown in FIG.
The carbon black is produced by introducing 1100 to 1200 kg / H under the conditions of the spray angle (θ), the gas-liquid ratio, and the setting position (L) of the raw oil burner (distance from the lower part of the furnace to the tip of the burner) shown in Fig. It carried out (4: atomized air, 5: mixing part). The characteristic values of carbon black obtained by these methods are shown in Table 1 as Examples 1 to 3.

Reference Examples 4 and 5 (Comparative Production Example) Carbon black was produced under the conditions shown in Table 2 using a vertical furnace having a cylindrical reaction furnace as in Reference Examples 1 to 3. The characteristic values of carbon black obtained by this method are shown in Table 1 as Comparative Examples 1 and 2. That is, in Reference Examples 1 to 3, as compared with Reference Examples 4 and 5, the fuel oil is increased,
Sufficient atomized air improves combustibility and raises the furnace temperature. Since the raw material oil is sprayed over a wide area in the furnace, the jetting speed of the raw material oil is dispersed and reduced as compared with the narrow-angle spray burner, and the frequency of collision of droplet particles in the region forming the structure is reduced. Prevent development. In addition, undecomposed carbides (usually called grit) are increased due to the higher efficiency of contact with the high temperature part in the furnace.
Decrease. It is considered that such phenomena are occurring.

Reference Example 6 (Comparative Production Example) Using a horizontal furnace as shown in FIG. 2, 275 kg / H of fuel oil and 5500 Nm ³ / H of air were introduced into the center of the furnace from two locations tangentially and burned. The feedstock oil containing 50 ppm of potassium carbonate (C / H ratio 14.7, creosote oil with BMCI value of 158) is shown in Table 2 in the axial direction toward the center of the furnace using a single-fluid burner (holocon). 1490k depending on conditions of spray angle and setting position of raw oil burner
Carbon black was produced by introducing g / H. The characteristic values of the carbon black obtained by this method are shown in Table 1 as Comparative Example 3.

<Test Method> (1) Specific Coloring Power According to ASTM D3265-88 (2) Nitrogen Adsorption Specific Surface Area (S _N2 ) According to ASTM D3037-88 (3) DBP Oil Absorption According to ASTM D2414-88 (4) ) Aggregate diameter (D _mod ) by centrifugal sedimentation method 5 mg of dried sample is mixed with a small amount of activator, and 50 cc of 20% ethanol aqueous solution is added. 6 with an ultrasonic disperser
Disperse for minutes to obtain a measurement sample. An agglomerate diameter measuring device (manufactured by Joyes Loebl, USA) by centrifugal sedimentation method
Spin liquid (ion exchange water) 10m set to 00 rpm
Buffer solution (20% ethanol aqueous solution)
Inject 1 ml. Then, 0.5 ml of the measurement sample solution is added with a syringe to start the measurement. The maximum frequency diameter (D _mod ) in the obtained aggregate distribution curve is determined. (5) Coarse particle content (according to JIS K6221) 100 g of sample is passed by running water to JIS standard sieve (25μ)
Through. The residue on the sieve is dried at 105 ± 2 ° C. for 1 hour and then weighed, and the remaining amount is expressed as a percentage of the sample. (6) Ash content (JIS K6221) 10 was added to the magnetic crucible that was pre-baked at 750 ± 25 ° C for 1 hour.
Weigh 2.0 g of sample dried at 5 ± 2 ° C for 1 hour and
Ash in a muffle furnace at 0 ± 25 ° C, cool to room temperature in a desiccator, weigh, and display the remaining amount as a percentage of the sample.

(7) Ink Suitability (a) Preparation of Ink An ink was prepared using a planographic newspaper offset rotary ink material. 100 parts of resin varnish, 57.5 parts of mineral oil (including Gilsonite), 12.5 parts of petroleum solvent, and 47.5 parts of carbon black are premixed, and then 5 passes using a three-roll mill disperser to make a dispersion ink. Was prepared. (B) Adjustment of tack The tack value of the above dispersion ink was adjusted according to JIS K5701 using an incommeter. Target tack value 400 rpm Reading after 1 minute 4 ± 0.
3 (C) Dispersibility A small amount of the dispersed ink in each pass in a three-roll mill disperser when preparing the ink according to the test method (7) (a) is used and the grind meter described in JIS K5701 is used. Then, the dispersibility of each pass dispersion ink is measured. That is, the sample is placed on the gauge board of the grindometer whose groove depth changes linearly continuously from 25 μm to 0 μm, and the blade of the scraper is applied to the upper surface of the gauge board at a right angle to slide the sample. A film is formed, and the size of the crush in the sample is measured from the line generated there to evaluate the dispersibility.

(D) Optical suitability (i) Spreading color of spatula A standard sample after tack adjustment arbitrarily set by JIS K5701 and a comparative sample are separated by about 1 cm and are simultaneously spread on a spreading paper with a linear blade of a steel spatula, and thin. Make an ink film and use it as a spatula color sample. This standard sample was set to (10 points), and jetness and glossiness were indexed by visual judgment. (Ii) Color tone Using an MS color developing machine manufactured by Toyo Seiki, 0.2 cc of the tack adjusting ink is collected with an ink pipette and supplied to the roll. After spreading this evenly, spread it on newsprint. Then, without supplying new ink, the ink is spread evenly again and color is spread on the newly set newsprint. This is repeated 5 times. This 5th sheet of color-developed paper is measured with a colorimetric color difference meter (“300” made by Nippon Denshoku
A ″) is used to represent the b value of the Hunter color difference formula. The smaller the number, the stronger the bluish color tone.

(E) Flowability In accordance with JIS K5701, the tack adjusting ink was measured with a spread meter. Diameter D ₆₀ : Spreading diameter after 60 seconds is a numerical value in mm Slope S: Spreading diameter after 60 seconds − Spreading diameter after 6 seconds Intersection IC: Spreading diameter on the horizontal axis on the horizontal axis and spreading diameter on the vertical axis (mm) Plot the measured values for each measurement time on a semi-logarithmic graph with a uniform scale and connect them with a straight line. The value when this straight line is extended and crosses 1 second on the horizontal axis is read in mm and the intercept I
Let be C.

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

EFFECTS OF THE INVENTION According to the present invention, as the specific coloring power, the nitrogen adsorption specific surface area, the DBP oil absorption amount and the agglomerate diameter are maintained within a specific range, and the coarse particles of 25 μm or more and the ash content are smaller, the bluer is It is possible to obtain a carbon black that maintains the color tone, high jet black feeling, and good fluidity and has excellent dispersibility in the ink vehicle.

[Brief description of drawings]

FIG. 1 shows an example of a vertical carbon black manufacturing furnace having a cylindrical reactor according to the present invention.

FIG. 2 shows an example of a horizontal furnace.

FIG. 3 shows an example of a collision plate type two-fluid burner according to the present invention.

Claims (1)

[Claims] A specific coloring power: 80 to 115%, a nitrogen adsorption specific surface area: 50 to 100 m ² / g, a DBP oil absorption amount: 60 to 100 ml / 100 g, and an aggregate diameter by a centrifugal sedimentation method (D _mod ): 140 to 230 nm, 25 μm or more coarse particles: 50 ppm or less, ash: 0.25% or less, a carbon black for a printing ink.