JP2002138227A - Ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink composition which is excellent in color-developing properties and is stable even in continuous printing. SOLUTION: This ink composition for ink jet comprises a silicone surfactant and water or a mixture of water with a water-soluble organic solvent, the water having a specific resistance of 3 kΩ.cm or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an ink composition. More specifically, the present invention relates to a water-based ink used in ink jet recording in which recording is performed on a recording material by discharging and flying the ink using mechanical and thermal energy.

[0002]

2. Description of the Related Art The ink jet recording method is a method in which ink droplets are formed using a mechanical or thermal action, and these are used to form an image on a recording material such as paper. This ink jet recording method does not include processes such as development and fixing as in the recording method of electrophotography and the like, so that the apparatus can be easily miniaturized, and at the same time, high-speed recording and low-noise recording are possible. Such a recording method is also called an on-demand type.

Further, such a recording method called an on-demand type is applied more and more in the future because the recording apparatus is simple and colorization is easy. The most desired property of this recording method is to perform high-speed and continuous printing of high-quality printed matter comparable to electrophotography.

[0004] Problems in this ink jet recording include a decrease in color density and bleeding due to ink penetration. Although this is not a problem in ink-jet dedicated paper, it is considered as a phenomenon such as bleeding of ink and different color reproduction in PPC paper and the like generally used in offices and the like. Although various causes can be considered for this cause, it is mainly a phenomenon called so-called feathering, which is considered to be a phenomenon in which ink flows along the fibers of paper.

[0005] Various studies have been made to improve this problem. For example, JP-A-64-9279 and JP-A-64-63185 disclose a method of forming an image by depositing an acidic liquid and then depositing an ink containing a dye. When actually applied in an ink jet printer, the method disclosed herein requires the provision of an ink tank having another solution, so that the printer head becomes large, and also that more aqueous solution adheres to paper. It has the disadvantage of damaging the formed image, that is, the medium. For example, if the amount of the aqueous solution absorbed by the medium is large, cockling (paper wrinkles) is induced, which is disadvantageous in forming an accurate image.

[0006] In order to solve these problems, we have experimentally shown that the use of a fluorine-based surfactant as a surfactant can improve the bleeding and penetrability of the ink and improve the color density. I found it. However, the ink using the fluorine-based surfactant tends to be too familiar with the nozzle plate of the head that is usually subjected to a water-repellent treatment, and the initial discharge is good, but when continuous printing is performed, stable discharge is performed. Has proven difficult.

An object of the present invention is to provide an ink composition which has excellent coloring properties and can be stably ejected even in continuous printing.

[0008]

According to the present invention, there is provided a silicone-based surfactant and water or a mixed solvent of water and a water-soluble organic solvent, wherein water has a specific resistance of 3 kΩ · cm or more. The present invention provides an inkjet ink composition having the same.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have improved the bleeding and penetrability of an ink composition by combining a silicone-based surfactant with water having a specific resistance of 3 kΩ · cm or more. Was found, and the color density could be improved. Further, they have found that stable ejection is possible even when continuous printing is performed. This was found to be due to the fact that the use of a silicone-based surfactant slowed down the permeability of the ink composition and caused more color material to be present on the medium surface. In addition, it was found that it is important to combine with water having a specific resistance of 3 kΩ · cm or more in order to sufficiently bring out the water repellency and oil repellency peculiar to the silicone surfactant.

Furthermore, it has been found that the ink composition of the present invention is effective in preventing crystallization of the coloring material by using an organic solvent having a high boiling point and preventing drying of the ink composition in the head portion.

[0011] The specific resistance of water is defined as described above for the following reason. That is, the concentration of ions contained in water, which is the main solvent of the ink composition, can be expressed as the specific resistance of water. By setting the specific resistance value of the deionized water in the ink composition to 3 kΩ · cm or more, the temperature of the ink composition that occurs when printing is continuously performed using an ink jet printer causes the dye in the ink composition to increase. It is possible to prevent ions in water from reacting and solidifying.

More specifically, for the purpose of preventing the ink composition from drying and solidifying in the nozzle portion during the idle period of the ink jet printer, for example, calcium nitrate is added, and water as the main solvent of the ink contains chlorine ions. ,
A reactant of CaCl ₂ .n (H ₂ O) is formed. When this reactant becomes saturated, it solidifies in response to a change in temperature and causes clogging of the nozzle. Such a reaction is a good indication of the potential for ions in the water to react with other components in the ink composition and produce by-products. In order to prevent this, it is effective to limit the specific resistance of water as the main solvent.

Here, as the silicone-based surfactant, any surfactant known in the art can be used. For example, SN wet 123, Perenol S5 (manufactured by San Nopco), BYK-301, 302, 3
31, 333, 341, 345, 346, 348 (manufactured by Big Chemie). The silicone surfactant is preferably contained in the ink composition at a ratio of 0.001 to 5% by weight. If the amount is less than 0.001% by weight, bleeding may occur on the recording material of the ink composition, and the amount is more than 5% by weight.

Water having a specific resistance value of 3 kΩ · cm or more can be obtained by preparing a predetermined ion concentration by a conventionally known method such as deionization. In addition,
The non-resistance value is more preferably in the range of 30 kΩ · cm to 18 MΩ · cm. Here, water is preferably contained in the ink composition at a ratio of 40 to 90% by weight.

Next, the ink composition contains at least one kind of dye consisting of a dye or a pigment. Specifically, direct blue 1, 8, 71, 7
6,86,108,199,200,201,202,
236; Acid Blue 1,7,9,15,175,2
49; Direct Red 1, 9, 15, 17, 28, 3
7, 62, 75, 81, 83, 89, 99, 220, 2
25,227,243; Acid Red 35,44,5
2,82,92,94,115,131,134,15
4,186,249,254,289; Reactive Red 7,141,180; Direct Yellow 12,2
7, 28, 33, 39, 44, 50, 58, 85, 8
6, 87, 88, 100, 110, 142, 144; Acid Yellow 7, 17, 23, 42, 44, 79, 9
9, 142; direct black 19, 22, 32, 3
8, 51, 154, 168, Acid Black 2, Food Black 2, and carbon black. The pigment is preferably contained in the ink composition in a range of 0.05 to 5% by weight.

The ink composition may contain a water-soluble organic solvent. The water-soluble organic solvent has a function of controlling the permeability of the ink composition and ensuring the stability of the ink composition. In addition, it is preferable that the water-soluble organic solvent does not contain an ionic species that increases the specific resistance of water. As water-soluble organic solvents, glycerin, diethylene glycol, triethylene glycol,
N-methylpyrrolidone, 2-pyrrolidone, 1,5-pentanediol, 1,4-butanediol, 1,3-propanediol, polyethylene glycol, propylene glycol, thiodiglycol, triethylene glycol monobutyl ether, trimethylolpropane, 1,4
-Cyclohexanediol and the like. These water-soluble organic solvents may be used alone or in combination of two or more.
The water-soluble organic solvent is preferably contained in the ink composition in an amount of 60% by weight or less, more preferably 10 to 50% by weight.

Further, it is effective that the ink composition of the present invention contains urea and / or a urea-modified product in order to stabilize the dye. It is preferable that urea and / or urea-modified product is contained in the ink composition at a ratio of 0.001 to 5% by weight.

It is also effective to contain an alkanolamine as in the above urea.

The ink composition of the present invention is characterized by its constituent components and does not require a special device for attaching an acidic liquid to a conventional recording material. It also has the advantage of being usable.

The recording material to which the ink composition of the present invention is adhered is not particularly limited, and examples thereof include paper for exclusive use in ink jet printing and PPC paper which are known in the art.

[0021]

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. In the following Examples and Comparative Examples, "%" means% by weight. The deionized water used was adjusted by Yamato Auto Still WG261. Example 1 Acid Yellow 23 3% Glycerin 8% Diethylene glycol 8% 2-Pyrrolidone 4% Silicone surfactant (BYK-346) 1% Deionized water (specific resistance: 18 MΩ · cm)

Example 2 Reactive Red 180 2% Acid Red 52 1% Diethylene glycol 8% N-methylpyrrolidone 4% 1,5-pentanediol 8% Urea 1% Silicone surfactant (BYK-346) 1% Example 3 Reactive Red 180 2% Acid Red 52 1% Diethylene glycol 8% N-methylpyrrolidone 4% 1,5-pentanediol 8% Urea 1% Silicone-based interface Activator (BYK-346) 1% deionized water (resistivity: 100 kΩ · cm)

Example 4 Direct Blue 199 2% Acid Blue 9 1% Diethylene glycol 8% 2-Pyrrolidone 4% Thiodiglycol 8% Silicone surfactant (BYK-346) 1% Deionized water (specific resistance: 18 MΩ)・ Cm) remaining amount Example 5 carbon black 5% glycerin 8% diethylene glycol 8% 2-pyrrolidone 4% silicone-based surfactant (BYK-346) 1% deionized water (specific resistance value: 18 MΩ · cm)

Comparative Example 1 An ink composition was prepared in the same manner as in Example 1, except that the silicone-based surfactant was replaced with a non-silicone-based nonionic surfactant. Acid Yellow 23 3% Glycerin 8% Diethylene glycol 8% 2-Pyrrolidone 4% Nonionic surfactant (Ter manufactured by Union Carbide)
gitol 15-s-15) 1% deionized water (resistivity: 18 MΩ · cm)

Comparative Example 2 An ink composition was prepared in the same manner as in Example 2 except that the deionized water (specific resistance: 18 MΩ · cm) was replaced with deionized water (specific resistance: 2 kΩ · cm). Reactive Red 180 2% Acid Red 52 1% Diethylene glycol 8% N-methylpyrrolidone 4% 1,5-pentanediol 8% Urea 1% Silicone surfactant (BYK-346) 1% Deionized water (resistivity) : 2kΩ ・ cm)

Comparative Example 3 An ink composition was prepared in the same manner as in Example 4 except that the organic solvent was replaced with an organic solvent. Direct Blue 199 2% Acid Blue 9 1% Ethyl carbitol 8% 1,3-Dimethylimidazolidinone 4% Isopropyl alcohol 8% Silicone surfactant (BYK-346) 1% Deionized water (specific resistance: 18 MΩ)・ Cm)

Comparative Example 4 An ink composition was prepared according to the following formulation. Direct Black 168 3% Ethyl carbitol 8% Ethanol 8% Nonionic surfactant (Tergitol 15-s-15) 1% Deionized water (resistivity: 2 kΩ · cm)

Comparative Example 5 An ink composition was prepared in the same manner as in Example 5, except that the silicone surfactant was removed. Carbon black 5% Glycerin 8% Diethylene glycol 8% 2-Pyrrolidone 4% Deionized water (specific resistance: 18 MΩ · cm)

Comparative Example 6 An ink composition was prepared in the same manner as in Example 2 except that the silicone-based surfactant was replaced with a fluorine-based surfactant. Reactive Red 180 2% Acid Red 52 1% Diethylene glycol 8% N-methylpyrrolidone 4% 1,5-pentanediol 8% Urea 1% Fluorinated surfactant (Daikin Industries DS-403) 1% Deionized water (Specific resistance value: 2 kΩ · cm) Remaining amount The following experiment was performed using the ink compositions of Examples 1 to 5 and Comparative Examples 1 to 6.

Experiment 1: Continuous printing The above ink composition was applied to a desk jet 720C manufactured by HP.
Was used to study the number of printable sheets when printing was continuously performed at a print density of 15%. The number of printable sheets until the ink tank is filled with the ink composition and becomes empty is about 20
It is zero. In the experiment, when the ink composition became empty, the ink composition was refilled, and this operation was repeated until printing could no longer be performed. The case where the number of printable sheets exceeded 400 sheets was evaluated as ○, and the case where the number was less than 400 sheets was evaluated as ×. Experiment 2: Decapping property The ink composition was packed in an ink cartridge, and after printing 10 sheets, the ink cartridge was removed by a printer and left at room temperature for 1 day without capping.
After the standing, the case where the ink cartridge was attached to the printer again and printing was possible was evaluated as ○, and the case where printing was not possible was evaluated as x. Experiment 3: Ink bleeding Using the above ink composition, printing on various PPC papers,
The bleeding degree of the print sample was evaluated. A good case without bleeding was rated as ○, and a case with bleeding was rated as x.

Experiment 4: Color Density of Printing Ink A solid image was formed for each color using the above ink composition, and after being left for 1 hour, the recording density of the solid image was changed to X-Rite9.
38 (manufactured by X-Rite) to compare the color densities. Color density of yellow and cyan are those with a density of 1.1 or more. ○ Density is less than 1.1. × Magenta is density of 1.2 or more. ○ Density is less than 1.2. ×: Regarding black, those with a density of 1.3 or more were rated as ○, and those with a density of less than 1.3 were rated as ×.

Table 1 shows the results of Experiments 1 to 4.

[0033]

[Table 1]

In the table, Y1 and Y2 represent yellow, and M1 to M1.
M4 is magenta, C1 and C2 are cyan, Bk1
Bk3 means black. In addition, a blank column means that it is not used. In addition, Sharp
SF4AM2 and 4AM3, Xerox 3R9185
4, Hammermill 10326-7, Igep
a 840A80 means the type of various print media.

As shown in Table 1, when Example 1 is compared with Comparative Example 1 and Example 5 is compared with Comparative Example 5, it can be seen that good printing is possible when a silicone-based surfactant is used.

Comparing Examples 2 and 3 with Comparative Example 2, it can be seen that good printing is possible when the specific resistance of water is 3 kΩ · cm or more.

Further, when comparing Example 4 with Comparative Example 3, it can be seen that the decap characteristic is improved by including the water-soluble organic solvent.

As described above, an ink composition comprising at least a silicone-based surfactant and water having a specific resistance of 3 kΩ · cm or more has excellent coloring properties and enables stable ejection even when continuous printing is performed. And it turns out that it is hard to dry even if it is left.

Further, glycerin, diethylene glycol, triethylene glycol, N-methylpyrrolidone,
2-pyrrolidone, 1,5-pentanediol, 1,4-
At least one water-soluble organic solvent selected from the group consisting of butanediol, 1,3-propanediol, polyethylene glycol, propylene glycol, thiodiglycol, triethylene glycol monobutyl ether, trimethylolpropane, and 1,4-cyclohexanediol Including, by containing urea and / or urea denatured product,
It is understood that an ink composition having more excellent characteristics can be obtained.

In addition, as in Comparative Example 4, the one out of the conditions of the present invention has no effect.

Further, comparing Example 2 and Comparative Example 6, it can be seen that the number of printable sheets in continuous printing is increased by using a silicone-based surfactant as compared with that using a fluorine-based surfactant.

[0042]

According to the ink-jet ink composition of the present invention, the penetration of the ink composition into the recording material can be suppressed to an appropriate range, so that bleeding such as feathering can be prevented. The concentration of the ink composition on the recording material can be improved.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kiyoto Motoyama 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Hiroaki Nakaya 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Masaru Nakamura 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term within Sharp Corporation (reference) 2C056 FC01 FC02 2H086 BA52 BA59 BA60 BA62 4J039 AE11 BC07 BC09 BC13 BC37 BC50 BC54 BE01 BE03 BE04 BE12 BE22 CA03 CA06 EA15 EA16 EA17 EA19 EA44 EA47 GA24

Claims (4)

[Claims] 1. A water-soluble organic solvent comprising water and a mixed solvent of water and a water-soluble organic solvent.
An inkjet ink composition having a specific resistance of at least cm. 2. A silicone surfactant and 3 kΩ · c.
The composition according to claim 1, wherein water having a specific resistance of at least m is contained in proportions of 0.001 to 5% by weight and 40 to 90% by weight, respectively. 3. The water-soluble organic solvent is glycerin, diethylene glycol, triethylene glycol, N-methylpyrrolidone, 2-pyrrolidone, 1,5-pentanediol, 1,4-butanediol, 1,3-propanediol, polyethylene. Glycol, propylene glycol,
3. The composition according to claim 1, wherein the composition is selected from the group consisting of thiodiglycol, triethylene glycol monobutyl ether, trimethylolpropane, and 1,4-cyclohexanediol. 4. The composition according to claim 1, which comprises urea and / or a modified urea.