JPS603434B2 - jet printing ink - Google Patents

Description

[Detailed description of the invention] The present invention relates to aqueous jet printing inks.

More specifically, it is an excellent product that enables uniform and stable jetting over a long period of time without clogging the nozzle of a jet printer, and the surface tension of the ink droplets is not easily affected by the surrounding environmental temperature. The present invention relates to an aqueous jet printing ink having ink droplet generation properties. In recent years, a large number of jet printing printers have been developed because they are non-impact printers that are not affected by the shape of the printing surface and are high-speed and quiet.

For example, an ink-on-demand method uses a piezo element that generates distortion in response to an electrical pulse signal to cause a rapid volume change in the ink chamber, and generates only the necessary amount of ink from the nozzle. ; Electrostatic transfer method that applies pressure to the ink and generates ink droplets from the nozzle tip by electrostatic attraction; When generating ink droplets from the nozzle tip by electrostatic attraction, the ink is exposed to high frequency A number of ink droplet generation methods have been developed, including a method of applying sound waves; a method of generating ink droplets by force-feeding ink and applying high-frequency ultrasonic vibrations to the ink near a nozzle. Next, the method of adhering the ink droplets generated from the nozzle with a diameter of several microns to several millimeters as described above can be classified as follows: (1) A method in which the droplets are allowed to fly through space and adhere to the printing surface; (0) An electric field control method in which a charged ink droplet flies in an electric field, receives the necessary deflection by the electric field, and attaches to a predetermined printing position, or a method in which a pulse voltage is applied to the generated ink droplet. Ink droplets are electrically charged using a charge modulation method that applies a charge according to a predetermined amount of deflection, deflects the charged ink droplets flying in an electric field according to the amount of charge, and attaches them to a predetermined position on the printing surface. It is broadly divided into methods of controlling and adhering.

Various types of ink, such as water-based and oil-based inks, have been developed for use in these jet printers. In the various methods described above, in order to jet the ink as uniform particles or to control the ink particles, appropriate ink viscosity,
Surface tension and electrical properties are required. However, in any inkjet method, ink droplets must be continuously and stably ejected as uniform particles from a fine nozzle.

Therefore, the basic problem of inkjet printers is to completely prevent clogging of the nozzle portion and ensure continuous and stable generation of ink particles over a long period of time.

Another important point is that stable ink particles can be created again after a temporary pause. Naturally, fine nozzles can become clogged even by the adhesion of even a small amount of solid matter that does not fall into the solvent. Furthermore, even if a solid object adheres to a part of the nozzle, the ink ejection direction changes. Therefore, in order to eject ink particles continuously and stably, not only the viscosity and surface tension of the ink composition must be appropriate;
Completely remove the solvent-insoluble solid content in the ink composition, or
Alternatively, it is necessary to keep it stable in the state of ultrafine particles. It is also necessary to completely prevent the generation of solvent-insoluble solids over time. By the way, coloring in water-based jet ink compositions can be generally prevented by removing solvent-insoluble solids or by using water-soluble dyes.

Furthermore, when using pigments as colorants, ultrafine pigments with a stable dispersion state must be kept stable as ultrafine particles.
It is necessary to prevent agglomeration of particles and the generation of new solid content in the solvent. Water-based inks for jet printing have been known from the past, consisting of a polyhydric alcohol-based wetting agent, a coloring agent made of a water-based dye or various ultrafine pigments, water as a solvent, and various other additives. The ink had some instability in the generation of uniform ink droplets, and the negative effects on printed matter were increasingly visible.

In other words, since ink droplet volume (surface area) and deflection amount are interrelated, when ink droplets are controlled by electrostatic deflection, etc., if the generation of homogeneous droplets is unstable, individual droplet particles This has resulted in the disadvantage that the predetermined amount of charge applied to the printer varies, resulting in a significant deterioration in printing quality. Furthermore, it has been reported that when ink droplets are conventionally generated using electrostatic attraction, there is a region in which the state of particle generation changes significantly when the voltage is gradually increased. (Angoin et al., Journal of the Institute of Image Electronics Engineers, 1st Flash, No. 2, pp. 52-57, 1977
These regions are divided into a coarse particle generation voltage range, a fine particle generation voltage range, and an atomization voltage range from the low voltage side. By the way, in jet printing, the above-mentioned fine particle generation voltage range is utilized. Therefore, the wider the voltage range in which ink droplets in the form of fine particles can be stably obtained, the wider the range of application, which is preferable from a practical point of view. However, with conventional water-based inks for jet printing, it has not been possible to significantly expand this fine particle generation voltage range.

The present invention aims to eliminate the drawbacks of conventional water-based jet printing inks as described above, and aims to provide uniform and stable jetting over a long period of time without clogging the nozzle of the jet printing printer. Provided is an ink for jet printing which has excellent ink droplet generation characteristics and can greatly expand the voltage range for generating fine particles.

That is, the present invention provides an aqueous jet printing ink containing a water-bathable wetting agent, a coloring agent, and water as its main components, which is prepared by adding 0.002 to 1% by weight of perfluoroalkyl sulfonate. It depends.

The water-repellent wetting agent used in the present invention is one that is liquid at room temperature, and specifically includes polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol #300, glycerin, propylene glycol, etc. Alkyl ethers of polyhydric alcohols and their acetate esters, such as ethylene glycol monomethyl ether, diethylene glycol monobutyl ether,
Examples include ethylene glycol monomethyl ether acetate, tripropylene glycol methyl ether, etc.; hydroxyalkylformamides, such as hydroxyalkylformamides in which the alkyl group has 1 to 4 carbon atoms; and N-vinyl-2-pyrrolidone oligomer.

These humectants can be used alone or in mixtures. The wetting agent preferably has a content of 10 to 6 in the ink.
used in a range of % by weight.

Further, as the coloring agent used in the jet printing ink of the present invention, water-soluble dyes with good solubility in water, fine particle pigments with excellent dispersibility and dispersion stability, etc. can be used.

For example, C. 1.0irect BI fertilizer 236, C. 1.
DirectBlue203, C. 1. Direct
Blue202,C. 1. DirectBlue1fu
C, I, Acid Blue7・C, I, Acid B
I fertilizer 9・C, 1, Direct Yellow 144,
C. 1. Direct Yellowloo, C. 1.
Direct Yellow86, C. 1. Direc
t Yellow50, C. 1. Acid Yellow
wl, C. 1. Acid Yellow23, C. 1.
AcidGreen5, C. 1. Basic Viol
et39, C. 1. DirectRed23, C. 1
．． Direct Red227, C. 1. Direc
tRed225, C. 1. Acid Red87, C.
1. Acid Red92, C. 1. Ac;d Red
52, C. 1. Acid Red145, C. 1. Ac
idRed252,C. 1. Basic Red27,
C. 1. Basic Red46, C, 1. already sic
Red12, C, 1. BasicRed3〆C. 1.
DirectBlack51, C. 1. Direct
Blackl9,C. 1. Examples include DirectBlack. These colorants are preferably used in the jet printing ink in a range of 0.1 to 1% by weight.

Furthermore, the perfluoroalkylsulfonic acid salts used in the present invention include alkali metal salts or ammonium salts of perfluoroalkylsulfonic acids having 4 to 12 carbon atoms, but the most preferred are perfluoroalkylsulfonic acids. It is potassium. The perfluoroalkyl sulfonate in the present invention has the function of generating ink droplets uniformly and stably, and
It has the effect of greatly expanding the particle generation voltage range,
Furthermore, the wet/dry properties of paper can also be improved.

The perfluoroalkyl sulfonate is added in an amount of 0.002 to 1.0% by weight based on the ink. In the above range, if the amount added is less than 0.002% by weight, it will have little effect on the stable generation of ink droplets and will not contribute to the expansion of the voltage range for generating fine particles.

On the contrary, 1. If it is used in an amount exceeding 20% by weight, solid content will be generated in terms of solubility, resulting in loss of the nozzle portion, etc., which is not preferable. In particular, perfluoroalkyl sulfonate is 0.
．． Jet printing ink containing 01 to 1.0% by weight not only has a stable surface tension even when stored for a long period of time, but also maintains a stable surface tension even when the ambient temperature or the temperature of the ink changes. This is more preferable because it hardly changes and therefore stable droplets can be obtained at all times. In the jet printing ink of the present invention, a water-soluble solvent such as dioxane, acetone, diacetone alcohol, alkyl alcohol having 1 to 3 carbon atoms, dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, etc. may be used as necessary. One or more of: Viscosity modifiers, such as hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polypinyl alcohol, etc.; Antifungal and antiseptic agents, such as sodium dehydroacetate, 1,2-benzisothiazoline-3
-one amine salt, 6-acetoxy-2,4-dimethyl-m-dioxane, etc.: It is possible to add and mix one or more types of other conductivity imparting agents, various additives, etc. The jet printing ink of the present invention uses water as a solvent in addition to the above-mentioned components. Therefore, from the practical point of view of the inkjet system, it is preferable to adjust the viscosity of the ink during use (usually at room temperature) to fall within the range of 1.2 to 30 centipoise. The jet printing ink of the present invention can be obtained by uniformly mixing the above-mentioned components using a hawk and pestle. The thus obtained ink of the present invention has basic properties essential for a jet printing ink, such as no nozzle clogging, improved surface tension stability and ink liquid extrusion stability, and expanded fine particle generation voltage range. It is of great industrial value because it can significantly improve the The present invention will be explained in more detail with reference to Examples below.

Examples and Comparative Examples Each component shown in Table 1 was uniformly mixed to obtain a water-based ink for jet printing.

Each of the obtained inks was used to print on paper using a jet printer that utilizes electrostatic attraction.

The ink ejection stability and printing condition at that time were visually determined, and the particle generation voltage range (ΔE) was measured. The results are shown in Table 1. Table 1 (Note 1) Manufactured by 3M Company Name: Potassium perfluoroalky'resulfonate (Note 2)
Manufactured by Asahi Glass ■ Product Name: Esnal Perfluoroalkyl Phosphate It is clear from the comparative test results table that the conventional water-based inks for jet printing (Comparative Examples 1 and 2) have poor ink ejection stability. Even in the printed state, the ink dots were disordered, and the voltage range for atomization was also very narrow.

On the other hand, the jet printing ink of the present invention had very good ink ejection stability and printing condition, and the atomization voltage range was also greatly expanded.

Claims (1)

[Scope of Claims] 1. An aqueous jet printing ink containing a water-soluble wetting agent, a coloring agent, and water as the main components, in which 0.002 to 1% by weight of perfluoroalkyl sulfonate is added. ink. 2. The jet printing ink according to claim 1, wherein the perfluoroalkyl sulfonate is potassium perfluoroalkyl sulfonate.