JP2003138175A - Method for producing dispersed ink for ink jet and method for reutilizing bead - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing dispersed ink for ink jet, free from contamination of beads in ink and excellent in a jetting property as ink when dispersing ink by a water-based agitating mill using dispersing beads, and a method for reutilization of beads free from contamination of beads in ink and excellent in a jetting property as jet ink when reutilizing the beads by polishing, having >40 surface lost number by a polisher so that the surface lost number of the beads become <=40 and the dispersing ink. SOLUTION: This method for producing disperse ink for ink jet comprises producing the ink by using the wet type medium-agitating mill and these beads for disperse having <=40 surface lost number.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a dispersion ink for inkjet using a bead for dispersion (hereinafter, also simply referred to as "bead") and a method for reusing the bead, using a wet medium stirring mill. In the obtained ink, there is no bead contamination and a method for producing an inkjet ink dispersion ink having excellent ejection properties as an inkjet ink, and used beads whose surface desorption number exceeds 40 are treated with a polishing machine. The present invention relates to a method for recycling polished beads.

[0002]

2. Description of the Related Art In recent years, in many fields such as pigments and paints, fine powder particles containing less harmful impurities have been demanded even with the demand for higher performance and smaller size of dispersion liquids. Also,
At the same time, it is required to improve the efficiency of pulverization and dispersion of powder particles from the viewpoint of cost.

[0003] Further, due to the simplification of the post-process and the response to the environment, the water-based pulverization process is being started.

In order to satisfy these requirements, pulverization treatment in a water system by a wet medium stirring mill represented by a sand mill has come to be widely used. This media agitation mill uses high-speed rotating drums and agitating blades to move the crushing / dispersing media (balls and beads) and crush the objects to be crushed using the impact force, frictional force, and compression force of the kinetic energy.
Since the particles are dispersed, the efficiency of pulverization and dispersion increases as the momentum and speed of the media increase, but the momentum of the media increases, and the higher the speed, the higher the temperature of the slurry to be ground and the load applied to the media for crushing and dispersion. growing.

Therefore, beads are selected as the dispersion medium due to hardness, specific gravity, etc., but in the case of an aqueous system, the corrosive wear of the beads is further promoted, and the contamination of the medium (beads) in the obtained ink becomes a problem. As an inkjet ink, there is a problem that the inkjet head is clogged and the emission properties are deteriorated.

[0006]

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to disperse an ink in an ink when dispersed in an aqueous wet medium stirring mill using dispersion beads. There is no bead contamination and the method for producing an inkjet ink dispersion ink having excellent ejection properties as an inkjet ink and the number of desorbed beads on the surface during use is 4
Contamination of the beads in the ink is observed when those exceeding 0 are polished by a polishing machine, and the beads are reused by setting the surface desorption number of the beads to 40 or less and dispersed by an aqueous wet medium stirring mill. It is another object of the present invention to provide a method for reusing beads, which has excellent emission properties as an inkjet ink.

[0007]

The above object of the present invention can be achieved by the following constitutions.

1. A method for producing a dispersion ink for inkjet, which comprises using a wet medium stirring mill and using beads for dispersion having a surface desorption number of 40 or less.

2. 2. The method for producing a dispersion ink for inkjet as described in 1, wherein the beads for dispersion are zirconia beads or ceramic beads.

3. The number of surface desorption of the dispersion beads is 20.
The method for producing a dispersion ink for inkjet according to the above 1 or 2, characterized in that:

4. Beads used for producing a dispersion ink for inkjet, wherein when the number of surface desorption of the beads exceeds 40, the beads are polished by a polishing machine, and the number of surface desorption of the beads is set to 40 or less and reused. How to reuse.

5. 5. The method for reusing beads according to 4, wherein the beads are zirconia beads or ceramic beads.

That is, the inventors of the present invention measured the surface desorption number of the beads when the beads were dispersed in a water-based wet medium agitating mill in the production of an ink-jet dispersion ink, and the beads were determined by this surface desorption number. By controlling the exchange, it is possible to avoid contamination of beads in the ink obtained by the method for producing an inkjet dispersion ink, and to obtain a method for producing an inkjet dispersion ink having excellent ejection properties as an inkjet ink. In addition, the beads can be reused by polishing the beads whose surface desorption number in use (completed) exceeds 40 with a polishing machine and using the beads with the surface desorption number of 40 or less. Also found.

The present invention will be described in more detail below. The method for producing the inkjet dispersion ink of the present invention will be described.

The method for producing an ink jet dispersion ink of the present invention comprises a step (1) of stirring a colorant, a dispersant and an aqueous liquid medium with a stirrer, and a step (2) of further dispersing and stirring (preliminary dispersion) with a disperser. It is preferable to have.

Further, in the production method of the present invention, the colorant dispersion obtained by preliminary dispersion is further used as a medium by using a media type disperser such as a sand mill, and the surface desorption number of beads to be described later is 40. It has a step (3) of dispersing (main dispersion) using the following beads.

Further, the production method of the present invention preferably comprises a step (4) of diluting the colorant dispersion to a predetermined concentration.

A preferred example of the method for producing the ink jet dispersion ink of the present invention will be described below.

In the step (1), the colorant, the dispersant and the aqueous liquid medium are stirred with a stirrer. In this case, the compounding mass ratio of the dispersant and the aqueous liquid medium is from the viewpoint of dispersibility at the time of preliminary dispersion and main dispersion, and further handling at the time of preliminary dispersion and main dispersion, the former: the latter = 1: 200- The ratio is preferably 1: 1 and more preferably 1: 100 to 1: 2.

Further, in the present invention, it is more preferable to use at least one stirrer for the in-tank flow in this step, and at least one high-speed stirrer from the viewpoint of production efficiency.

In the step (2), the mixture of the colorant, the dispersant and the aqueous liquid medium obtained in the step (1) is further dispersed (preliminary dispersion) with a stirrer.

The stirring time and stirring temperature are preferably 0 to 80 ° C., more preferably 20 to 60 ° C., in the disperser for mainly crushing and dispersing. More preferably temperature 2
It is 0-40 degreeC.

An example of the high-speed agitator with a stator in the step (1) is, for example, IKA Ultra Turrax UT-65D. In addition, as a disperser that mainly performs in-row flow, the type does not matter, but it is a three-propeller type,
A paddle type suitable for circulation in the tank is preferable.

Further, the dissolver type is more preferable from the viewpoint of causing fluidization in the bath to break up large lumps of the colorant and increasing the dispersion speed. The peripheral speed of the stirrer for flowing in the tank may be set within a range that does not cause a large vortex in view of the flow state in the tank, and stirring Reynolds number, Weber number, etc. may be used for optimization, but 5 m / s More preferably, it is more preferably 8 m / s or more because it also has a crushing force.

The positions of the plurality of stirrers may be determined while observing the flow in the tank, but if they are too close to the bottom and the wall of the kettle, the overall flow becomes unbalanced and it causes bubbling, which is not preferable.

The pre-dispersion kettle may be equipped with a heat-retaining jacket to prevent temperature rise, and may be kept warm with cold water or the like. The amount of colorant compounded is
From the viewpoint of predispersion and dispersibility at the time of main dispersion, and further handling property at the time of predispersion and at the time of main dispersion, the blending mass ratio with the aqueous liquid medium is set to colorant: aqueous liquid medium = 1: 33 to 1: 1. It is preferable that the ratio is 1:25 to 1: 2.

The dispersion time is preferably 5 to 120 minutes in order to sufficiently wet the pigment with the mixture of the dispersant and the aqueous liquid medium, and 10 to 30 from the viewpoint of improving production efficiency.
More preferably, it is minutes.

The concentration of the colorant in the colorant dispersion obtained in the main dispersion step is adjusted so as to sufficiently wet the colorant with the mixture of the dispersant and the aqueous liquid medium, and further in the preliminary dispersion and the main dispersion. From the viewpoint of handleability and viscosity control, 3 to 50 mass%
Is preferable, and more preferably 7 to 35% by mass. The temperature during dispersion is preferably 80 ° C or lower, more preferably 70 ° C or lower, and further preferably 60 ° C.
It is the following.

In order to keep the temperature at the time of dispersion low, the dispersion liquid may be cooled by using a jacket kettle. Although water is used as the cooling water, if further cooling is required, an antifreeze solution at about 0 ° C may be used.

In the main dispersion step (3), the colorant dispersion obtained in the preliminary dispersion in the step (2) is made into fine particles by a more powerful wet medium stirring disperser. As a dispersing machine, a wet medium stirring mill such as a sand mill using beads for dispersion (for example, a media type dispersing machine), a high-pressure homogenizer, a pin mill, a colloid mill, or other powerful dispersing machine is available as long as it can disperse into submicrons. However, a media type disperser such as a sand mill is preferable from the viewpoint of mass production and efficiency. The media type disperser may be of any type such as a vertical type or a horizontal type, and may be an annular type having a high energy density such as a diamond fine mill manufactured by Mitsubishi Heavy Industries, Ltd. As the dispersion beads (media), those having a high specific gravity are preferable, and the average diameter of beads is usually 1.0 mm or less, preferably 0.5 mm.
The following is more preferably 0.3 mm or less. The maximum peripheral speed of the rotating part of the disperser is preferably 7 to 15 m / s, more preferably 8 to 12 m / s.

The average particle size of the dispersed particles after the main dispersion is the emission property,
It should be selected from the viewpoint of stability, and the average particle size of turbulence distribution is preferably 400 nm or less, further 250 nm.
The following are preferred. More preferably, it is 200 nm or less. However, if the main dispersion is carried out for a long time, a good colorant dispersion cannot be obtained due to aggregation and / or thickening due to overdispersion, which is not preferable.

It is also preferable that the particle size distribution is small. Good pre-dispersion is important in order to make the particle size distribution uniform, and the particle size after dispersion in the pre-dispersion step is preferably 200 times or less the particle size after dispersion in the main dispersion step. It is more preferably 150 times or less, further preferably 100 times.
It is less than twice.

As the present dispersion system, a dispersion system is used in which a dispersion liquid is received from a tank using a pump through a dispersion machine to another tank, and if the particle size has not reached, a repeating system is used, and the dispersion liquid is dispersed from the tank using a pump. There is a circulation method that continues this by returning to the original tank through. The circulation method is preferable from the viewpoint of reduction of initial cost, but the pass method may be used depending on the nature of the raw material, and a production method in which the circulation method is used from the middle of the dispersion method in the initial dispersion stage is also preferable.

In the present invention, the surface of the beads of the present dispersion can be observed with an electron microscope. As a pretreatment, sputter coating of platinum-palladium 2 nm was performed and observed with an electron microscope at a magnification of 3000 times in a field of view of 100 μm × 100 μm. Areas of 0.001 μm ² or more and less than 1.3 μm ² were counted and a field of view of 10 μm × 10 μm was observed. The number of holes is defined as the number of surface desorption.

The number of surface desorption of the beads for dispersion of the present invention is 40.
It is below, preferably below 20.

The lower limit is not particularly limited, but if it is intentionally limited, it is 0 to 1. Also, in order to suppress the wear of beads, lower the temperature during dispersion, increase the solvent ratio during dispersion and add water after dispersion, and use partial heat in the disperser using an annular disperser such as Mitsubishi Heavy Industries Diamond Fine Mill. It is also preferable to suppress

As the beads, zirconia beads, ceramics
Beads, alumina beads, Al ₂O₃-ZrO₂-S
iO₂Among these, zirconia bee among these
(ZrO₂), The ceramic beads have the effect of the present invention.
It is preferable in that it plays better.

Examples of the zirconia beads include YTZ beads manufactured by Nikkato and HIP (Hot isos) thereof.
Tactic products) and Toray ceram beads manufactured by Toray are preferably used.

The operating conditions of the disperser depend on the performance requirements of the product, but the corrosive wear of the beads during water-based crushing is directly correlated to the temperature and time. Therefore, the disperser is cooled to a low temperature during dispersion by raising it to a high temperature. It is preferable to operate at a peripheral speed and process in a short time.

The aqueous liquid medium preferably used in the present invention is usually 30% by mass or more, preferably 50% by mass or more,
More preferred is a liquid medium containing 75% by mass or more of water, and may further contain a hydrophilic organic solvent such as an organic solvent such as alcohol, isopropanol, ethylene glycol or diethylene glycol, and the water-insoluble organic solvent is also an aqueous liquid. It may be contained as long as it does not impair the homogeneity of the medium.

The ink-jet dispersion ink has a form in which a dye is dissolved and dispersed in the above aqueous liquid medium as a coloring agent.
It has a form in which a pigment is dispersed.

One of the preferred colorants used in the present invention is a disperse dye, which is a dye which is hardly soluble or insoluble in an aqueous liquid medium, has ordinary hydrophobicity and hydrophilicity, and is usually printed with polyester or the like. It is a well-known colorant that can be used as an application.

Representative examples include azo type, anthraquinone type and indoaniline type disperse dyes. It is used as an ink dispersed in an aqueous liquid medium due to its poor solubility or insolubility.

Further, a pigment is mentioned as a colorant preferable in the present invention. Pigments are roughly classified into inorganic pigments and organic pigments, but they are powders of coloring agents that are insoluble in water, oil and the like, and are used by being dispersed and added in the material as coloring agents for printing inks and paint plastics. Excellent in robustness because it is insoluble in liquid media.

The inorganic pigments include carbon black, and the organic pigments include azo, triphenylmethane, quinoline, anthraquinone, phthalocyanine and other organic pigments.

A dispersant is added to improve the dispersibility of the colorant. Examples of the dispersant include those having a large molecular weight and expecting a protective colloid effect, and those having a small molecular weight and a large surfactant activity, which are generally called surfactants. They are classified into anions, cations, and nonions according to their polarities. Moreover, these can be used individually or in combination of 2 or more types.

Examples of the high molecular type of the dispersant include proteins such as gelatin and casein, natural rubber such as gum arabic, glucooxide such as saponin, cellulose derivatives such as alkyl cellulose, carboxyalkyl cellulose and hydroxyalkyl cellulose, and lignin sulfone. Acid salt, styrene-maleic acid copolymer salt, vinylnaphthalene-maleic acid copolymer salt, sodium salt of β-naphthalenesulfonic acid formalin condensate, anionic polymer such as polyphosphoric acid, polyvinyl alcohol, polyvinylpyrrolidone, A nonionic polymer such as polyalkylene glycol can be used.

Examples of the anionic surfactant include alkylbenzene sulfonate, alkylnaphthalene sulfonate, alkane or olefin sulfonate, alkyl sulfate ester salt, polyoxyethylene alkyl or alkylaryl ether sulfate ester salt, alkyl phosphate salt. , A surfactant selected from the group consisting of alkyl diphenyl ether disulfonates, ether carboxylates, alkyl sulfosuccinic acid ester salts, α-sulfo fatty acid esters and fatty acid salts, condensates of higher fatty acids and amino acids, naphthenic acid salts, etc. be able to. Anionic surfactants preferably used are alkylbenzene sulfonates (particularly linear alkyls), alkanes or olefin sulfonates (particularly secondary alkane sulfonates, α-olefin sulfonates), alkyl sulfates. Salts, polyoxyethylene alkyl or alkylaryl ether sulfate ester salts (especially polyoxyethylene alkyl ether sulfate ester salts), alkyl phosphates (especially monoalkyl type), ether carboxylates, alkyl sulfosuccinates, α-sulfo fatty acid esters and A surfactant selected from the group consisting of fatty acid salts, particularly preferably,
Alkylbenzene sulfonates (especially linear type), polyoxyethylene alkyl or alkylaryl ether sulfuric acid ester salts (especially polyoxyethylene alkyl ether sulfuric acid ester salts) and alkyl sulfuric acid ester salts.

As the cationic surfactant, an aliphatic amine salt, a quaternary ammonium salt, a sulfonium salt, a phosphonium salt or the like can be used.

As the nonionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester. And a surfactant selected from the group consisting of alkyl (poly) glycoxides. The nonionic surfactant preferably used is a surfactant selected from polyoxyethylene alkyl ethers and polyoxyethylene alkylaryl ethers.

In addition to the above components, other necessary components such as a pH adjusting agent are mixed to prepare a dispersion ink for ink jet.

According to the fifth and sixth aspects of the present invention, when the number of surface desorption of the beads used in the method for producing an ink jet dispersion ink reaches 100 or more, the beads are polished by a polishing machine and the surface desorption of the beads is carried out. It is a method of reusing beads, characterized in that the number is 40 or less and the beads are reused. Even if the beads are used, the effect of the present invention can be obtained.

As the polishing machine of the present invention, a polishing machine (for example, barrel polishing machine) for polishing the dispersion medium used in an ordinary dispersing machine (for example, sand mill) is used.

[0054]

The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1 (Preliminary Dispersion Step) In the preliminary dispersion step, the following components were stirred for 20 minutes at a peripheral speed of 13 m / s with a stator-equipped stirrer at a peripheral speed of 5 m / s.

Vanillex RN 13 parts (sodium lignin sulfonate: manufactured by Nippon Paper Industries) Glycerin 12 parts Water 48 parts Dye C.I. I. Pigment Yellow 17 (27 parts) was added to the vessel containing the stirrer, and the mixture was stirred for 30 minutes to disperse the pigment to obtain a pigment preliminary dispersion liquid. The particle size distribution of the disperse dye in the obtained preliminary dispersion liquid was measured four times using SALAD-2000 (manufactured by Shimadzu Corporation), and the measured particle sizes were averaged to obtain an average particle size. The average particle size was 12 μm.

After carrying out preliminary dispersion, Ashizawa bead disperser LMZ-4 and beads (the number of desorbed beads on the surface of the beads was 13) were Nikkato YTZ 0.3.
12.5 kg of mmφ beads were used for main dispersion until the average particle size of the dispersed particles reached 170 nm.

Formulation 1 Vanillex RN (manufactured by Nippon Paper Industries) Lignin sulfonic acid sodium salt 13 parts Glycerin 12 parts Pure water 48 parts Disperse dye C.I. I. Disperse yellow 149 (Disperse dye in preliminary dispersion liquid) 27 parts The dispersion liquid was adjusted to the following amount, and then filtered through a 3 μm membrane filter to obtain an ink.

Formulation 2 Dispersion liquid 40 parts Di-2-ethylhexyl-sodium sulfosuccinate 0.5 parts Ethylene glycol 24 parts Glycerin 24 parts Pure water 11.5 parts Average particle size of dispersion liquid, Zr concentration in ink and ink The emitting property was evaluated by the following method. The results are shown in Table 1.

Example 2 Preliminary dispersion and main dispersion were carried out in the same manner as in Example 1 except that beads of Nikkato YTZ (surface desorption number 31) were used in main dispersion, and inks were prepared and evaluated for each item.

Example 3 Used Nikkato YTZ beads (surface desorption number 10
0) was preliminarily dispersed and finally dispersed to prepare an ink in the same manner as in Example 1 except that Nikkato YTZ beads in which the number of surface desorption of beads was 10 were polished by a barrel polisher. evaluated. The results are shown in Table 1.

Comparative Example 1 Preliminary dispersion and main dispersion were carried out in the same manner as in Example 1 except that Nikkato YTZ beads having a bead surface desorption number of 110 were used, and an ink was prepared to evaluate each item. The results are shown in Table 1.

(Observation of surface of beads) After fixing each sample on the sample table, Pt-Pd was sputter coated to a thickness of about 2 nm and subjected to a conductive treatment. After that, S manufactured by Hitachi, Ltd.
-800 type scanning electron microscope (Scanning Ele)
The surface was observed with an accelerating voltage of 10 kV and a sample inclination angle of 0 degree by ctron Microscope), and the number of desorbed surfaces of the beads of the above-mentioned Examples and Comparative Examples was determined.

(Average particle size of dispersed particles in dispersion) mal
Vern Zetasizer 1000 (Malvern Co., Ltd.)
The scattering particle size distribution was measured 5 times, and the measured particle diameters were averaged to obtain the average particle diameter of the dispersed particles in the dispersion liquid.

(Zr Concentration) An ICP emission spectrometer was used for measuring the Zr concentration in the ink. It is necessary to dissolve the sample in order to perform ICP emission analysis. Microwave is used for decomposition of the sample, and the analysis sample can be decomposed rapidly under high temperature, and can decompose the wide range of samples with high accuracy and certainty.
Digest 6, manufactured by Pro Lab) was used.

As the acid used for decomposition, a mixed solution of sulfuric acid and nitric acid was used to make the sample a solution. The obtained solution was analyzed using an ICP emission spectrometer (Seiko Denshi Co., SPS4000). Analysis wavelength 339.198 nm, output 1.
2 kW was used. The standard solution was used by adding a reagent for atomic absorption spectrometry (manufactured by Kanto Chemical Co., Inc.) to a mixed acid solution decomposed without a sample using a microwave wet decomposition apparatus under the same conditions as the decomposition of the sample.

(Ejectivity) Using an on-demand piezo shear mode drive type ink jet printer having 64 emission nozzles, emission was performed at a drive frequency of 8.2 kHz at an emission speed of 10 m / s and the emission state was visually observed for 2 hours. However, the number of nozzles that cannot maintain a normal emission state, such as intermittent emission in which emission sometimes disappears and oblique emission in which the emission direction shifts obliquely, was counted. Generally, the smaller the number of nozzles that cannot eject, the better the ejection stability.

[0068] The number of nozzles that cannot be ejected is 0: ◎ Number of nozzles that cannot be ejected is less than 1-2: ○ The number of nozzles that cannot be ejected is less than 2 to 6: △ The number of nozzles that cannot be emitted is 6 or more: x.

[0069]

[Table 1]

As is clear from Table 1, the number of surface desorption of the beads of the present invention is small (within the range of the present invention).
It can be seen that when beads are used, the concentration of Zr mixed in is low and an ink with good emission properties can be produced.

It was also found that the sample in which the number of desorbed surface of used beads was polished to 40 or less also exhibited the effect of the present invention, and it was confirmed that the beads can be reused. .

[0072]

As demonstrated in the examples, the method for producing an ink-jet dispersion ink according to the present invention is free from the bead contamination in the ink when dispersed by an aqueous wet medium stirring mill using beads, and the ink-jet ink As a result, it has an excellent effect of emitting.

In addition, in the method for reusing beads according to the present invention, the beads whose surface desorption number in use exceeds 40 are polished by a polishing machine so that the surface desorption number of the beads is 40 or less. Thus, the effect of the present invention was obtained.

Continued front page    F-term (reference) 2C056 EA14 FC01                 4D063 FF13 FF37 GA10 GD24                 4J039 BA13 BA26 BA39 BD02 BE01                       BE22 CA06 DA02 DA07 DA08                       GA24

Claims (5)

[Claims] 1. A method for producing a dispersion ink for inkjet, which comprises using a wet medium stirring mill and using dispersion beads having a surface desorption number of 40 or less. 2. The method for producing an inkjet dispersion ink according to claim 1, wherein the dispersion beads are zirconia beads or ceramic beads. 3. The method for producing a dispersion ink for inkjet according to claim 1, wherein the number of desorbed particles on the surface of the dispersion beads is 20 or less. 4. When the beads used in the production of the ink-jet dispersion ink have a surface desorption number of more than 40, the beads are polished with a polishing machine so that the number of the surface desorption of the beads is 40 or less and the beads are reused. And a method for reusing beads. 5. The method for reusing beads according to claim 4, wherein the beads are zirconia beads or ceramic beads.