JPS6136382A - Ink for ink jet recording - Google Patents

Abstract

PURPOSE:The titled ink having low viscosity, slightly evaporating, having improved frequency response, long-term recording stability, etc., obtained by dissolving oil-soluble dye in a mixed solvent of a specific high-boiling solvent and a specified low-viscosity organic solvent. CONSTITUTION:Oil-soluble dye is dissolved in a mixed solvent consisting of (A) a high-boiling solvent (e.g., diisopropylnaphthalene, etc.) having >=200 deg.C boiling point, and (B) a low-viscosity organic solvent (e.g., ethylene glycol monoethyl ether, etc.) having <=5mPa.s viscosity, and preferably 0.01-0.5mol%/l solution is obtained, to give the aimed ink. A ratio of the component B is preferably <=80wt% based on total solvent amounts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an inkjet recording ink, and more specifically, it is used in a device that performs recording by ejecting ink from an ink jetting port using pressure or electrostatic attraction, and is a stable inkjet recording ink. The present invention relates to an inkjet recording ink that enables recording and high-definition printing.

[Background of the invention]

Currently, there are various methods for generating ink droplets in inkjet recording devices, such as electrostatic acceleration type, pressurized vibration type, pressurized jet type, and pressure pulse type. In order to perform stable recording from a minute ink ejection height, the ink is required to have appropriate physical properties.

Furthermore, it is desirable to use a solvent component that is as difficult to evaporate as possible for these inks in order to minimize clogging of the ink jet orifices and changes in the physical properties of the ink due to drying of the ink components and to achieve excellent recording stability. On the other hand, in order to have excellent frequency response and to eject ink faithfully in response to signals, the ink is required to have as low a viscosity as possible.

However, although it is required to use a high boiling point organic solvent for ink that is difficult to evaporate, in general, high boiling point organic solvents have large molecules and a large difference between room temperature and boiling point, so they are inevitably high in temperature. It has viscosity. On the contrary, low-viscosity organic welding agents have small molecules, so they have a low boiling point and tend to evaporate easily. Therefore, it is difficult to achieve both a high boiling point and low viscosity, and it has not been possible to create a single ink that satisfies both conditions.

[Summary of the invention]

The present invention has been made in view of the above points, and an object of the present invention is to provide an inkjet recording ink that has a low viscosity, a high boiling point, and is difficult to evaporate.

Therefore, the inkjet recording ink according to the present invention has an oil-soluble dye dissolved in a mixed solvent consisting of a combination of a high boiling point solvent having a boiling point of 200° C. or more and a low viscosity organic solvent having a viscosity of 5 vaPa, s or less. It is characterized by:

According to the present invention, it is possible to provide inkjet recording ink that has low viscosity and is difficult to evaporate, and therefore has high frequency response and can perform jetting faithfully to pulse signals. There is an advantage that an ink with good long-term recording stability can be provided.

[Detailed description of the invention] The present invention will be explained in more detail.

As mentioned above, the inkjet recording ink according to the present invention is prepared by dissolving an oil-soluble dye in a mixed solvent of a high boiling point organic solvent having a boiling point of 200° C. or more and a low viscosity organic solvent having a viscosity of 5 taPa, s or less. be.

In order to develop an inkjet recording ink that has water resistance, recording stability, and enables high-quality recording, the present inventors prepared an ink consisting of a combination of various oil-soluble dyes and various organic solvents. We have conducted injection experiments using
It has been discovered that by mixing a certain type of high boiling point organic solvent and a low viscosity organic solvent, it is possible to prepare an ink that is less evaporative and has a lower viscosity.In other words, by dissolving an oil-soluble dye in a high boiling point organic solvent, It was discovered that by adding a certain low-viscosity organic solvent to this ink, the viscosity of the ink was rapidly reduced, and this led to the present invention.

Figure 1 shows the measurement results of ink viscosity when cyclohexanol, a high boiling point, high viscosity organic solvent, is mixed with chlorobenzene or ethanol, a low viscosity organic solvent. In the figure, ■ indicates an oil-soluble dye. 2 shows the viscosity of an ink prepared by dissolving an oil-soluble dye in cyclohexanol and ethanol.

As is clear from Figure 1, the ink consisting only of oil-soluble dye and cyclohexanol has a high viscosity of 66.7 mPa, S, but when 20% of chlorobenzene or ethanol is added to it, the viscosity of the ink decreases. 15.6 and 12.8 mPa, about one-fifth of that, respectively.

In both cases, it decreases to S and adds 50% to about 2
It decreased to 2.6 mPa, s, which is one-fifth. moreover,
It was found that when the proportion of the low viscosity solvent ranged from 40% to 100%, there was almost no change in viscosity, so the viscosity of the ink remained constant.

The high boiling point solvent used in such mixed solvents is 200℃
However, if the boiling point of this high-boiling point solvent is less than 200°C, the inkjet recording ink will easily evaporate, making it difficult to maintain sufficient recording stability (
This is because there is a risk that the

The above-mentioned high boiling point solvent is desirably one that can easily dissolve oil-soluble dyes, and examples of such solvents include phthalate esters such as dimethyl phthalate, diethyl phthalate, and dibutyl phthalate, and succinic acid. Aliphatic dibasic acid esters such as diisopropyl, dibutyl succinate, diisobutyl adipate, dioctyl adipate, 1-methoxynaphthalene,
- Naphthalene derivatives such as chlornaphthalene, diethylene glycols such as diethylene glycol monoethyl ether and diethylene glycol acetate, ethylene glycols such as ethylene glycol cyphthyl ether, ethylene glycol monophenylethyl acetate, and ethylene glycol monophenyl ether, phosphoric acid tri-n - Phosphate esters such as butyl and tricresyl phosphate, fatty acids such as oleic acid, linoleic acid, and lylunic acid, diarylethane [e.g. 5MS-296
(Japan Petrochemical), KMC210 (Kureha Chemical)], alkyl-substituted biphenyl (former PB (monosanto)), hydrogenated terphenyl (HB40 (Monken 1-)),)
Realyl dimethane [Marotherm S (Hüls)]
] and other industrial petroleum oils.

In addition, as a low viscosity 18 solvent, 5 mPa at room temperature
This is because if the viscosity exceeds 5 mPa, s, the viscosity may not be reduced sufficiently when mixed with the above-mentioned high boiling point solvent.

Examples of such low viscosity solvents include ethyl butyrate,
71M fatty M esters such as isopentyl butyrate, ethyl isovalerate, isoamyl valerate, isobutyl isovalerate, diethyl malonate, diethyl succinate, DDE
Aliphatic dibasic acid esters such as (Dupont), sulfur and phosphorus compounds such as diethyl sulfite, dibutyl sulfite, triedyl phosphate, anisole, phenethole, p-cresol ethyl ether, dibdel ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, Ethers such as ethylene glycol diethyl ether and ethylene glycol dibutyl ether; alcohols such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether;
One or more types of ethylene glycol acetate a such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, and ethylene glycol monobutyl ether acetate can be mentioned.

Although such high boiling point organic solvents and low viscosity organic solvents are used as a barrier, it is easy to understand that two or more types of such organic solvents may be used in combination depending on the purpose. .

The high boiling point organic solvent and the low viscosity organic solvent are preferably a mixture of 80% or less of the low viscosity organic solvent. This is because if it exceeds 80%, the amount of high-boiling organic solvent becomes too small, which may lead to a decrease in recording stability.

The oil-soluble dye dissolved in such an organic solvent is not limited in the present invention, and any oil-soluble dye conventionally used in this type of technology can be used.

The concentration of this oil-soluble dye is preferably 0.01 to 0.5
mo1%/l. If it is less than 0.0 In+ol %/1, the dye may be too thin and a good image may not be obtained; on the other hand, if it is less than 0.5 mol %/7! This is because, if it exceeds the above range, the viscosity becomes high, it becomes difficult to dissolve, and furthermore, there is a risk that recording stability will deteriorate.

The present invention will be explained in detail below.

Example 1 Oil-soluble dye 5 parts by weight Diisopropylnaphthalene 4 units Ethylene glycol monoethyl ether 50 parts by weight The above components were thoroughly stirred to prepare an ink.

The viscosity of the ink, simply calculated proportionally from the viscosity of the solvent itself, is 7.2 a+Pa,s, but the actual measurement result is 4.
．． It was 0 tsPa,s. When a recording experiment was conducted using this ink with an inkjet printer, it showed high frequency response and excellent long-term recording stability.

Example 2 Oil-soluble dye 5 parts by weight Diarylethane (MMC210) 40 parts by weight Diethylene glycol dimethyl ether 55 parts by weight The above components were thoroughly stirred to prepare an ink.

The viscosity of the ink, simply calculated proportionally from the viscosity of the solvent itself, is 4.8 mPa, s, but the actual measured result is 3.
Q mPa,s. When we conducted a recording experiment using this ink in an ink-siendo printer, it showed high frequency response and excellent long-term recording stability.

Example 3 Oil-soluble dye 5 parts by weight Diisopropylnaphthalene 40 parts by weight Diethylene glycol monoethyl ether 55 parts by weight The above components were thoroughly stirred to prepare an ink.

The viscosity of the ink, simply calculated proportionally from the viscosity of the solvent itself, is 10.7 mPa.s, but the actual measurement result is 7.7 mPa.s.
5 a+Pa,s. When a recording experiment was conducted using this ink with an inkjet printer, it showed high frequency response and excellent long-term recording stability.

Example 4 Oil-soluble dye 5 parts by weight diisopropylnaphthalene 40 parts by weight oleic acid
15 parts by weight diethylene glycol dimethyl ether 40 parts by weight The above components were thoroughly stirred to prepare an ink.

The viscosity of the ink, which was simply proportionally calculated from the viscosity of the solvent itself, was 1), 3a+Pa, s, but the actually measured result was 4.2 Pa, s. When a recording experiment was conducted using this ink with an inkjet printer, it showed high frequency response and excellent long-term recording stability.

Example 5 Oil-soluble dye 5 parts by weight Oleic acid 45 parts by weight Diethylene glycol Triethyl phosphate 50 parts by weight The above components were thoroughly stirred to prepare an ink.

The viscosity of the ink, simply calculated proportionally from the viscosity of the solvent itself, is 1B, 3mPa, s, but the actually measured result is 4.
It was 8 sPa, s. When a recording experiment was conducted using this ink with an inkjet printer, it showed high frequency response and excellent long-term recording stability.

Example 6 Oil-soluble dye 5 parts by weight dimethyl phthalate 45 parts by weight dibutyl ether
50 parts by weight of the above components were thoroughly stirred to prepare an ink.

The viscosity of the ink, simply calculated proportionally from the viscosity of the solvent itself, is 8.9+wPa,s, but the actually measured result is 2.
It was 1 mPa, s. When a recording experiment was conducted using this ink with an inkjet printer, it showed high frequency response and excellent long-term recording stability.

Example 7 Oil-meltable dye '14 5 parts by weight Dimethyl phthalate 45 parts by weight Ethylene glycol monomethyl ether acetate 50 parts by weight The above components were thoroughly stirred to prepare an ink.

The viscosity of the ink, simply calculated proportionally from the viscosity of the solvent itself, is 5.6s+Pa,s, but the actually measured result is 3.6s+Pa.s.
It was 1 raPa,s. When a recording experiment was conducted using this ink with an inkjet printer, it showed high frequency response and excellent long-term recording stability.

Example 8 Oil-soluble dye 5 parts by weight dimethyl phthalate 45 parts by weight isopentyl butyrate
40 parts by weight diisopropylnaphthalene
50 parts by weight of the above components were thoroughly stirred to prepare an ink.

The viscosity of the ink, simply calculated proportionally from the viscosity of the solvent itself, is 9.7 mPa,s, but the actually measured result is 5.2
+mPa,s. When a recording experiment was conducted using this ink with an inkjet printer, it showed high frequency response and excellent long-term recording stability.

Example 9 Oil-soluble dye 5 parts by weight Oleic acid 15 parts by weight Diethylene glycol monoethyl ether, 30 parts by weight Aliphatic dibase ester <DBE, DuPont) 50 parts by weight
The above ingredients were thoroughly stirred to prepare an ink.

The viscosity of the ink, simply calculated proportionally from the viscosity of the solvent itself, is 9.5 mPa,s, but the actually measured result is 5.5
It was mPa,s. When a recording experiment was conducted using this ink with an inkjet printer, it showed high frequency response and excellent long-term recording stability.

(Effects of the Invention) As explained above, according to the inkjet recording ink of the present invention, an oil-soluble dye is dissolved in a mixed solvent consisting of a combination of a high boiling point organic solvent and a low viscosity organic solvent, so that the ink has a low viscosity. However, it has the advantage of having good properties that make it difficult to evaporate.

Therefore, when this inkjet recording ink is used for recording with an inkjet printer, it has the advantage of exhibiting high frequency response, being able to eject faithfully to pulse signals, and having excellent long-term recording stability.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the change in viscosity depending on the amount of the high boiling point solvent and low viscosity solvent mixed when an oil-soluble dye is dissolved in a mixed solvent of a high boiling point solvent and a low viscosity solvent. ■...Viscosity change of inkjet recording ink with oil-soluble dye dissolved in cyclohexanol and chlorobenzene, 2...Viscosity change of inkjet recording ink with oil-soluble dye dissolved in cyclohexanol and ethanol. Applicant's agent Masashi Amemiya Figure 1

Claims (1)

[Claims] (1) An oil-soluble dye is mixed with a high-boiling point solvent having a boiling point of 200°C or higher under a pressure of 5 mPa. An inkjet recording ink characterized by being dissolved in a mixed solvent consisting of a combination of low-viscosity organic solvents having a viscosity of s or less.