JPH11302585A - Ink for ink jet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject ink capable of preventing bubbles from forming and stably carrying out printing over a long period and useful for a continuous type recording device by regulating a bubble height measured by using a specific device to a specific value or below. SOLUTION: This ink jet ink is obtained by regulating the bubble height when one h passes from the start of dropping the ink by using a device capable of circulating the ink from an ink reservoir 5 which is a graduated cylinder of 500 mL having 5.5 cm inside diameter through a pipe 6 for discharging the ink at a constant flow rate with a pump 1 and having a discharge outlet 2 having 3 mm inside diameter for discharging the ink of the pipe 6, located above in the vertical direction from the center of the ink reservoir 5 and direction to the ink reservoir 5 under conditions so as to provide 270 ml/min ink discharge rate, 300 ml ink reservoir capacity and 40 nm distance from the discharge outlet 2 to the water surface of the ink reservoir 5 under the discharge outlet 2 to <=450 ml expressed in terms of graduations of the graduated cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink used in an ink jet recording apparatus.

[0002]

2. Description of the Related Art Ink jet recording apparatuses are roughly classified into a continuous type and a drop-on-demand type.
Generally, the former has a mechanism to control the flight direction of ink droplets continuously ejected from nozzles, and ink droplets not used for printing are collected, returned to the ink tank, and reused. Whereas the latter does not have it.

[0003] In the continuous type ink jet recording apparatus, ink droplets not used for printing hit a collecting place (hereinafter referred to as a gutter), and the gutter may generate foam. The foam has poor fluidity and overflows from the collection location to stain the recording medium and hinder the flight of the printed ink droplets.

In this regard, although the purpose is different,
In JP-A-1399963, it is proposed to use an ink in which the amount of remaining foam becomes 0 after 5 minutes in the ink evaluation by the Ross Miles method, and it seems to be effective for foam generation countermeasures.

However, even if such an ink is used,
In fact, foam is generated and may overflow.

[0006]

DISCLOSURE OF THE INVENTION In view of the above situation, the present invention provides an ink jet ink which does not generate bubbles, particularly an ink which is preferably used for a continuous ink jet recording apparatus. This enables stable printing.

[0007]

SUMMARY OF THE INVENTION The present invention has been achieved as a result of intensive studies under conditions closer to reality than the Ross-Miles method, and the gist thereof is as follows.

That is, the present invention is characterized in that the ink is dropped under the following specific apparatus and conditions, and the foam height when one hour has passed from the start of dropping the ink is 450 ml or less on the scale of the measuring cylinder. Ink for inkjet printing.

Specific device and conditions In the piping for discharging the ink, the ink is made to circulate at a constant flow rate from the ink reservoir by a pump.
The port for discharging ink in the pipe is a device which is located substantially vertically above the center of the ink reservoir and faces the ink reservoir, and has the following dimensions and shapes.

Inner diameter of pipe for discharging ink vertically downward: 3 mm Ink discharge speed: 270 ml / min Distance from pipe discharge port to water surface of ink reservoir below:
40cm Ink reservoir shape: 500ml measuring cylinder with 5.5cm inner diameter (or equivalent) Ink reservoir volume: 300ml

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

In the present invention, the nature of the ink is important.
As the composition itself, an ink composition suitable for a purpose for a recording medium such as paper, film, or cloth is used.
That is, the composition is not limited as long as the ink properties defined by the present invention are satisfied.

[0013] Generally, it is composed of at least a colorant and a medium, and a dye or a pigment is used as the colorant. In the case of dyes, particularly when used for ink-jet dyeing of fabrics and the like, for example, disperse dyes and the like when the fabric is polyester, acid dyes and reactive dyes when polyamides and the like, and direct dyes when cellulose is used. And reactive dyes. These are appropriately selected according to the recording medium, and the present invention is not limited thereto.

[0014] The medium generally comprises a main medium (eg, water) and an anti-drying agent (eg, glycols). As glycols, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5- Pentanediol, neopentyl glycol, 1,6-hexanediol, hexylene glycol and the like are preferred examples, but are not limited thereto. In addition, as appropriate, defoamers, pH adjusters, preservatives,
Other modifiers for physical properties may be appropriately used, but the present invention is not limited thereto.

The defoaming agent is not always an essential component, and the object of the present invention can be achieved without the defoaming agent. In many cases, however, it is preferable to add the defoaming agent. Often obtained. Many antifoaming agents are already commercially available, and oils, fats, fatty acids, fatty acid esters, alcohols, ethers, phosphate esters, amines, amides, silicones, etc., and combinations thereof are known. ing. The composition of the antifoaming agent used in the present invention is not particularly limited, but according to the knowledge of the present invention, a block copolymer type nonionic surfactant of polyethylene oxide and polypropylene oxide, and a polyoxyalkylene ester type nonionic surfactant An ionic surfactant, a polyoxyalkylene phosphate ester type anionic surfactant, a carboxylate type anionic surfactant and the like are preferably used. The ink preferably has a surface tension of 25 to 55 dyne / cm, more preferably 3 to 55 dyne / cm.
It is 2-55 dyne / cm. The viscosity of the ink is preferably 1 to 10 cP, more preferably 1 to 4 cP.
P.

In the present invention, the properties of the ink are as follows: the ink is dropped under the following specific device and conditions, and the foam height when one hour has passed since the dropping of the ink was 450 ml or less on the scale of the measuring cylinder. Is important, and it has been found that this is associated with suppressing foaming near the gutter.

The specific device used in the present invention is essentially
In the Ross Miles method and the apparatus described in JIS K 3362, the liquid is circulated. However, the height is only 90 cm, and it is difficult to say that the handling is simple. I decided. That is, as schematically shown in FIG. 1, the apparatus used in the present invention is formed so that ink is circulated at a constant flow rate from the ink reservoir 5 by the pump 1 to a pipe 6 for discharging ink. The opening 2 for discharging the ink of No. 6 is a device that is located vertically upward from substantially the center of the ink pool 5 and faces the ink pool. The dimensions and shapes are as follows.

Inner diameter of pipe for ejecting ink vertically downward: 3 mm Ink ejection speed: 270 ml / min Distance from the outlet of the pipe to the water surface of the ink reservoir below:
40 cm Ink reservoir shape: 500 ml graduated cylinder with 5.5 cm inner diameter (or equivalent) Ink reservoir volume: 300 ml Ink that satisfies the evaluation using the above device does not generate foam in the gutter portion. Also, the height of the foam 4 is
450 m on the scale of the measuring cylinder 7 when 2 hours have passed
It is more preferably 1 or less. It is still more preferable that the foam height after 4 hours has passed is 450 ml or less on the scale of the measuring cylinder.

The ink-jet ink of the present invention is preferably used as an ink for a continuous ink-jet recording apparatus, but is also used in an on-demand ink-jet recording apparatus such as a piezo method, a thermal method or a bubble method. It can be preferably used because it has the effect of suppressing the generation of air bubbles at the same time.

[0020]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Example 1 C.I. dispersed by using a dispersant disclosed in JP-A-61-213273. I. Disperse Ye
An ink composed of ll 114, water and 1,4-butanediol was prepared.

First, when the ink is ejected for 30 seconds using the evaluation apparatus of the present invention, the foam height of the graduated cylinder scale immediately after the ejection is stopped is 330 ml (substantially about 30 ml), and after about 5 minutes, approximately 300 ml (substantially 0 ml). )Met.

Next, FIG. 3 shows the results obtained by using this ink according to the evaluation method of the present invention using the evaluation apparatus of the present invention.

This ink did not generate foam in the gutter section 12 of the charge control type continuous ink jet recording apparatus schematically illustrated in FIG.

FIG. 2 is a schematic view showing the periphery of the gutter portion of the charge control type continuous ink jet recording apparatus. The ink is ejected from an ink ejection port 9 opened in the inkjet head 8, and when a drop occurs, a charge is given from a charging electrode 10. When the charged ink droplet passes between the deflecting electrodes 11, the flying direction of the ink droplet is bent in accordance with the amount of charge and the deflection voltage (a typical example is 14), and a part of the gutter 12 is formed. The rest land on the recording medium 13 for printing. Although not shown in FIG. 2, the ink droplets that have landed on the gutter 12 are collected, returned to the ink tank, and sent to the inkjet head 8 by a pump.

Comparative Example 1 The dispersant in Example 1 was replaced with JP-A-61-213273.
Ink was prepared by substituting a dispersant having a higher HLB, which is different from that of Example 1, although it is a dispersant specified in the publication.

First, when the ink was ejected for 30 seconds using the evaluation apparatus of the present invention, the foam height of the graduated cylinder scale immediately after the discharge was stopped was 340 ml (substantially about 40 ml), and after 5 minutes, 320 ml (substantially about 20 ml). )Met.

Next, FIG. 3 shows the results obtained for this ink according to the evaluation method of the present invention using the evaluation apparatus of the present invention.

This ink generated foam in the gutter portion 12 of the ink jet recording apparatus, and eventually overflowed to contaminate the recording medium.

Comparative Example 2 The dye of Example 1 was replaced with C.I. I. Disperse B
ink was prepared in place of lue60.

First, when the ink is ejected for 30 seconds using the evaluation apparatus of the present invention, the foam height of the graduated cylinder scale immediately after the stop of the ejection is 340 ml (substantially about 40 ml), and 320 ml (substantially about 20 ml) after 5 minutes. )Met.

Next, the results obtained by using the evaluation apparatus of the present invention for this ink according to the evaluation method of the present invention are shown in FIG. 3 (approximate to Comparative Example 1).

This ink generated foam in the gutter portion 12 of the ink jet recording apparatus, and eventually overflowed to contaminate the recording medium.

Comparative Example 3 To the ink of Comparative Example 2, acetylene glycol was added as an antifoaming agent.

First, when the ink was ejected for 30 seconds using the evaluation apparatus of the present invention, the foam height of the graduated cylinder scale immediately after the ejection was stopped was 320 ml (substantially about 20 ml), and after 300 minutes, approximately 300 ml (substantially 0 ml). )Met.

Next, FIG. 3 shows the results obtained by using this ink according to the evaluation method of the present invention using the evaluation apparatus of the present invention.

This ink generated foam in the gutter portion 12 of the ink jet recording apparatus, and eventually overflowed.

Example 2 A dispersant specified in JP-A-61-213273, which is different from that of Example 1, and is dispersed using a lower HLB dispersant. I. Disperse
FIG. 3 shows the results obtained by using the above-described evaluation apparatus for an ink composed of Blue 79, water, hexylene glycol, and neopentyl glycol.

This ink is used as a gutter 1 in a continuous ink jet recording apparatus of the ink droplet charge control type.
In No. 2, no foam was generated.

Example 3 FIG. 3 shows the results obtained by adding an antifoaming agent (Textport DY-300F manufactured by Nikka Chemical Co., Ltd.) to the ink of Comparative Example 2 and using the above-described evaluation apparatus.

This ink did not generate foam in the gutter portion 12.

[0042]

According to the present invention, bubbles are not generated in the gutter portion of the ink jet recording apparatus, and stable ink jet recording can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an evaluation device of the present invention.

FIG. 2 is a schematic view of the periphery of a gutter portion of a multi-level deflection charge control type continuous ink jet recording apparatus used in the embodiment.

FIG. 3 is an evaluation result diagram of the present invention for inks used in Examples and Comparative Examples.

[Explanation of symbols]

 1: Pump 2: Ink ejection port 3: Ink flow 4: Foam 5: Ink pool 6: Ink pipe 7: 500ml measuring cylinder with 5.5cm inner diameter 8: Ink jet head 9: Ink ejection port 10: Charge electrode 11: Deflection electrode 12: gutter 13: recording medium 14: four typical examples of ink trajectories

Claims (3)

[Claims] (1) Dropping ink with a specific device and under the conditions specified in the text, and the height of the foam one hour after the start of dropping the ink is measured by a scale of a measuring cylinder.
ml or less. 2. The ink-jet ink according to claim 1, wherein the ink-jet ink is used in an ink-jet recording apparatus provided with a mechanism for collecting the ink discharged from the ink discharge port without using it for printing. 3. A block copolymer type nonionic surfactant of polyethylene oxide and polypropylene oxide, a polyoxyalkylene ester type nonionic surfactant, a polyoxyalkylene phosphate ester type anionic surfactant, and The inkjet ink according to claim 1, further comprising at least one surfactant selected from the group consisting of carboxylate type anionic surfactants.