JPH0443943B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to direct azo dyes containing no impurity components. More particularly, the present invention relates to the use of a black direct azo dye containing no impurity components as a coloring component of an inkjet recording liquid.

Prior Art Direct azo dyes are used as coloring ingredients in a variety of applications. However, commercially available direct azo dyes contain many organic impurities, such as compounds produced by side reactions during the synthesis process, unreacted substances, and compounds produced by chemical bonding of unreacted substances. It is. In particular, when a black direct azo dye is used as a coloring component of an ink, these impurities are known to cause many problems. For example, during ink production, filters may become clogged, reducing productivity, and when ink liquid is applied to an inkjet printer, particles may precipitate in the nozzle if the printer is left unused for a long period of time. This also causes particles to precipitate when the ink is stored for a long period of time under high or low temperature conditions. In addition, when using a black direct azo dye in an inkjet recording liquid, increasing the dye content in the ink to increase image density may cause clogging, and in charge-controlled inkjet systems, the jetting direction may become unstable. There is a problem with becoming. Therefore, as a method to solve this problem, in the on-demand inkjet method, the nozzle part of the printer is capped when the printer is not in use, or a solvent that dissolves the dye is supplied to the nozzle part when the printer is not in use, and the nozzle eye is closed. How to prevent clogging, and when clogging occurs, manually or automatically apply pressure higher than the pressure applied to the ink in the head pressure chamber during normal use to remove the substance causing the clogging from the nozzle. A method is used to remove it in parts. but,
Adopting these methods has the drawbacks of restricting the structure of the printer and increasing costs. In addition, in charge-controlled ink jet systems, a charging electrode is usually placed just in front of the nozzle, so it is difficult to arrange a nozzle cap like the one described above. When the nozzle is clogged, the ink does not fly in the specified direction, so the ink is not collected in the gutter and contaminates the inside of the printer, such as the charging electrode, making it impossible to print, so it cannot be adopted. There is.

Purpose The present invention was made in view of the above problems, and its gist is to directly remove impurity components from an azo dye using benzyl alcohol or a solvent containing it. The object of the present invention is to use direct azo dyes containing no impurity components as coloring components. Another object of the present invention is to use a black direct azo dye containing no impurity components in a black recording liquid. Furthermore, an object of the present invention is to provide a printer that can perform stable jetting even if the printer is left unused for a long period of time without changing the direction of jetting, and has high image density, excellent water resistance, light resistance, and abrasion resistance. It is an object of the present invention to provide a stable recording liquid that provides a stable image and does not generate particles even when stored for a long period of time or exposed to high or low temperature conditions.

Other objects of the invention will become apparent from the description below.

Structure The present invention involves directly performing a liquid phase-liquid phase extraction operation between an azo dye solution and benzyl alcohol alone or a mixture of other solvents that are compatible with benzyl alcohol but substantially incompatible with water. The purpose of this method is to transfer impurities to a liquid phase containing benzyl alcohol to provide a direct azo dye from which impurities have been removed.

Among the direct azo dyes from which impurity components are removed according to the present invention, examples of black dyes include CI Direct Black 4, CI Direct Black 17, CI Direct Black 19,
CI Direct Black 38, CI Direct
Black 51, CI Direct Black 56, CI
Direct Black 74, CI Direct Black 75, CI Direct Black 77, CI Direct Black 154, and these compounds with different substituents, these compounds with ethylene oxide groups, and sulfonic acid groups. Derivatives such as those in which the cation of is substituted can be mentioned. Among these dyes, CI Direct Black 19, CI Direct Black 154, and derivatives of these compounds are particularly preferred in view of their solubility in water and organic solvents that are compatible with water, and their non-polluting properties. be able to. Of course, other direct azo dyes can also be used for the purposes of the present invention.

In the present invention, when benzyl alcohol is used alone to remove impurity components, it takes a considerable amount of time to separate the dye aqueous solution layer and the benzyl alcohol layer, so a centrifugal extractor is used to increase the separation speed of both layers. is recommended. Alternatively, by mixing benzyl alcohol with another solvent that is compatible with benzyl alcohol but is not substantially compatible with water, the difference in specific gravity between the aqueous dye solution and the dye solution can be increased. The separation rate can be further increased. At this time, examples of other solvents include n-hexane, n-pentane, dimethyl ether, isopropyl alcohol, n-butyl alcohol, diethyl ether, benzene,
Organic solvents such as toluene, methyl isobutyl ketone, and cyclohexane can be used, but in terms of extraction efficiency, _C2 - _C6- such as dimethyl ether can be used.
Alkyl ethers and _C3 - _C10 -alkyl alcohols such as isopropyl alcohol are particularly effective. In addition, when using a mixed solvent with benzyl alcohol, if the proportion of benzyl alcohol in the mixed solvent is small, the extraction efficiency will decrease, so benzyl alcohol should be used at least 30% by weight or more.
It is preferable to contain 60% by weight or more. Furthermore, in order to accelerate the drying of the dye after removing impurity components, there may be mentioned a method of washing the remaining benzyl alcohol with another solvent that has a low boiling point, easily evaporates, and dissolves benzyl alcohol. Solvents for this purpose include, for example, ether, acetone, n
-propyl alcohol, i-propyl alcohol, n-hexane, tetrahydrofuran, chloroform, dioxane, trichloroethylene, ethyl alcohol, methyl alcohol, toluene, benzene, cyclohexane and the like.

In the solvent extraction method used in the present invention to remove impurity components, a dye solution obtained by directly dissolving an azo dye in a solvent such as water that is substantially incompatible with benzyl alcohol is extracted with benzyl alcohol as the main component. This is a method in which impurities are transferred to the liquid phase containing benzyl alcohol by bringing it into contact with a liquid and performing an extraction operation between these liquid phases.

Such liquid phase-liquid phase extraction methods include, for example, a method using a Soxhlet extractor, a method in which a dye powder is dispersed in a solvent, and then a filter or a centrifuge is used to separate the dye from the solvent.
This method has a faster extraction rate and higher extraction efficiency than a method in which extraction is performed between solvents, and is extremely advantageous industrially.

Although it is currently unclear what structures of compounds are extracted by the extraction method using benzyl alcohol in the present invention, it is believed that this extraction method is particularly effective for direct azo dyes. It is presumed that the compound contains unreacted coupler. Further, according to the solvent extraction according to the present invention, the main component of the black direct dye does not substantially migrate into the extraction solution, so there is an advantage that a dye containing no impurity components can be obtained in high yield.

Next, as an application example of the direct azo dye containing no impurity components according to the present invention, a case where a black dye is used as a coloring component of a recording liquid will be described below.

The black direct azo dyes free of impurity components according to the invention can be used in recording liquids containing at least two components: a water-soluble organic solvent and water. In addition to the above-mentioned components, other additives such as specific electrical conductivity regulators, antiseptic and fungicides, PH regulators, etc. may be added as necessary.

Examples of water-soluble organic solvents include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol,
Triethanolamine, methyl carbitol, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, triethylene glycol monomethyl ether, formamide, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, valerolactone, caprolactone etc. can be used. Increasing the content of these organic solvents in the ink is generally effective in preventing nozzle clogging due to their wetting action, but since it reduces the drying properties during printing,
The total weight of these organic solvents is 10-50% in the ink
It is preferable that it is in the range of . Furthermore, among the above organic solvents, those containing a mixed solvent of polyhydric alcohols such as ethylene glycol and diethylene glycol and one of their alkyl ethers and glycerin can be mentioned as particularly preferable for the purpose of the present invention. .

Specific electrical conductivity regulators include lithium chloride,
Sodium chloride, potassium chloride, lithium bromide,
Sodium bromide, potassium bromide, lithium iodide, sodium iodide, potassium iodide, lithium nitrate, potassium nitrate, sodium nitrate, sodium sulfate, ammonium chloride, sodium acetate,
Salts such as sodium formate can be added.

As a preservative and a fungicide, 2,2-dimethyl-6
-acetoxy-dioxane, sodium dehydroacetate, sodium benzoate, potassium sorbate,
Sodium 2-pyridinethiol-1-oxide, etc. can be added. Further, as a pH adjuster, sodium hydroxide, sodium carbonate, triethanolamine, lithium hydroxide, sodium hydrogen carbonate, etc. can be added. In addition, dye solubilizers such as urea, anionic surfactants, nonionic surfactants, sodium paratoluenesulfonate, oxygen absorbers, rust preventives, ultraviolet absorbers,
Dyes can be added for complementary colors, solubility improvement, and infrared absorption.

EXAMPLES The present invention will be explained in more detail by way of examples as well as comparative examples, but the present invention is not limited thereto.

Example 1 20% by weight of black dye CI Direct Black 19
Pour 1000 ml of the aqueous solution (Orient 200-L) into a separating funnel with a capacity of 2, add 300 ml of benzyl alcohol, and shake for 30 minutes with a shaker.
After standing for a period of time, the dye solution layer and benzyl alcohol layer were separated. The separated benzyl alcohol extract was heated under vacuum to dryness, and the solid content was measured to be 4.4% by weight.

Comparative Example 1 The same operation as in Example 1 was carried out using chromium form, benzene, toluene, chlorobenzene, and
Carbon disulfide, methyl isobutyl ketone, nitrobenzene, ethyl ether, n-butanol, n-
When using pentane, cyclohexane, cyclohexanol, and n-propyl alcohol, chloroform, benzene, toluene, chlorobenzene, n-propyl alcohol, carbon disulfide, methyl isobutyl ketone, and nitrobenzene were emulsified with an aqueous dye solution. The separation of the liquid layer was incomplete. In addition, when the solvent of each extract was evaporated to dryness in the same manner as above and the solid content in the extract was measured, all values were smaller than benzyl alcohol. In this measurement, if the separation of layers was poor, an extract was obtained by centrifugation. The measured values were as follows.

Chloroform 0.9% Benzene 1,9〃 Toluene 2.2〃 Chlorobenzene 2.4〃 Carbon disulfide 1.1〃 Methyl isobutyl ketone 1.2〃 Nitrobenzene 4.1〃 Ethyl ether 1.3〃 N-pentane 0,4〃 Cyclohexane 0.6〃 Cyclohexanol 2.1 〃 n-propyl alcohol 2.4〃 Example 2 In Example 1, the black dye was
When the same operation was performed in place of Black 154 (manufactured by Daiwa Kasei Co., Ltd.), layer separation was possible after standing for 2 hours. In addition, the solid content in the extract is 5.2%.
It was hot.

Comparative Example 2 Using the various solvents described in Comparative Example 1, the same operations as in Example 2 were carried out to measure liquid separability and solid content in the extract. As a result, it was difficult to separate the liquid layer using chloroform, benzene, toluene, chlorobenzene, methyl isobutyl ketone, nitrobenzene, and n-propyl alcohol.
Furthermore, the solid content in the extract was also lower than when benzyl alcohol was used.

Application example 1 After repeating the same operation as in Example 1 five times to remove the moisture of the dye aqueous solution using an evaporator, the dye solution was dried for 20 hours using a vacuum dryer at 0.5 mmHg and 80°C. and obtained purified dye.

Using this dye, an ink was prepared according to the following recipe, and heated and stirred at 60°C for 5 hours.

Purified dye (CI Direct Black 19) 5% Glycerin 7% Ethylene glycol 23% Sodium dehydroacetate 0.5% Water 64.5% This ink was applied to a pressure of 0.5 using a Teflon filter (manufactured by Millipore) with a pore size of 0.22 μm and a diameter of 47 mm.
When filtrated at Kg/cm ² , it was possible to filtrate 153 g of ink in 5 minutes.

When this ink was filled into an ink cartridge of a charge control type printer having 30 nozzles with an inner diameter of 30 μm and ejected at a particle generation frequency of 100 KHz, stable ejecting characteristics were obtained.
After stopping the jetting, the nozzle was left at room temperature and humidity for one month, and then the jetting was started again, and the jetting position before and after leaving each nozzle was measured at a position 35 mm away from the nozzle. There was no case where the injection position shifted by more than 200 μm before and after being left alone.

Comparative Example 1 In place of the purified dye in Application Example 1, a commercially available dye (aqueous solution) was dried and solidified as it was, and the same formulation and stirring as in Application Example 1 were carried out to prepare an ink. When this ink was passed under the same conditions as in Application Example 1, only 3 g of ink was passed. Furthermore, when we similarly measured the deviations in the injection positions before and after leaving them, we found that six nozzles had deviations of 200 μm or more.

Application Example 2 Using the purified dye used in Application Example 1, an ink was prepared according to the following recipe.

Purified dye (CI Direct Black 19) 6% Glycerin 8% Diethylene glycol 15% N-methyl-2-pyrrolidone 12% Sodium p-toluenesulfonate 0.2% Sodium 2-pyridinethiol-1-oxide 0.1% Water 58.7% When the ink was subjected to filtration under the same conditions as in Application Example 1, it was possible to filtrate 122 g.

After degassing this ink, use a nozzle with a hole diameter of 40 μm to
own. When filled into an ink cartridge of an on-demand printer and ejected at a particle generation frequency of 1KHz, stable ejection characteristics were obtained. After stopping the eruption, it was left at room temperature and humidity for two months, and the eruption experiment was conducted again to see if stable eruption was possible. Out of the 30 nozzles, not a single one failed to eject. There were two cases in which injection stability was poor.

Comparative Example 2 In place of the purified dye in Application Example 2, a commercially available dye was dried and solidified as it was, and an ink was prepared by stirring according to the same recipe as in Application Example 2. When this ink was subjected to the same conditions as in Application Example 1, only 1.5 g of ink was obtained.

Further, when the jetting characteristics of the printers after being left unused were investigated in the same manner as in Application Example 2, there were two printers that could not be jetted and nine printers that had unstable jetting.

Application example 3 After repeating the same operation as in Example 2 twice and removing the water content of the dye aqueous solution using an evaporator, the apparently dry dye powder was placed in a Soxhlet extractor, and the dye powder was extracted using isopropyl alcohol as a solvent. Extraction was performed for 5 hours to remove benzyl alcohol remaining in the dye. After the Soxhlet extraction, the dye was dried in a vacuum dryer at 60°C under a pressure of 0.5 mmHg.
Dry for an hour.

When the same test as in Application Example 1 was carried out by replacing the dye in Application Example 1 with this dye, the excess amount was 195 g, and the number of nozzles in which the ejection position was shifted by 200 μm or more before and after leaving was 1.

Comparative Example 3 A test was conducted using the same ink formulation as in Application Example 3, except that a commercially available dye was used as is instead of the purified dye.
20g, and the number of nozzles whose injection positions shifted by 200 μm or more before and after being left alone was 7.

Application example 7 When ink was prepared using the same formulation as application example 2 except that the purified dye obtained in application example 3 was used and the test was conducted in the same manner, the excess amount was 164 g, and there was no ink that could not be ejected after standing. Poor injection stability 3
It was individual.

Comparative Example 4 When an ink was prepared using the same formulation as in Application Example 2 except that the commercially available dye CI Direct Black 154 was used as is, and the test was conducted in the same manner, the excess amount was 18 g, and the ink could not be ejected after standing. There were 4 of them, and 12 of them were unstable.

Application example 5 Put 1000 g of a 3% aqueous solution of black dye Direct Black 17 (manufactured by Sumitomo Chemical Co., Ltd.) into the separating funnel in step 3, add 150 ml of benzyl alcohol to this, shake it for 15 minutes in a shaker, and then add ethyl alcohol. Add 300 ml of ether, shake for 5 minutes, and let stand for 4 hours.
The lower dye aqueous solution layer was separated. The same extraction operation was repeated five times for this aqueous dye solution.
After the ether and water in the aqueous dye solution after the extraction operation were evaporated in an evaporator, the dye powder was placed in a Soxhlet extractor and extracted using acetone as a solvent to remove benzyl alcohol remaining in the dye. Apply this dye to 0.5mm in a vacuum dryer.
The purified dye was obtained by drying at 60° C. for 6 hours under Hg pressure.

Using this dye, an ink was prepared according to the following recipe, and heated and stirred at 60°C for 5 hours.

Purified dye (Direct Black 17) 2% Polyethylene glycol (molecular weight 200) 15% Glycerin 5% Methyl carbitol 5% Triethanolamine 1% Sodium benzoate 0.3% This ink was subjected to filtration under the same conditions as Application Example 1. However, the overdose amount was 95g. In addition, when the printer was used to measure the deviation of the ejection position before and after the printer was left in the same manner as in Application Example 1, two nozzles were found to be deviated by 200 μm or more.

Comparative Example 5 The ink was prepared in the same manner as in Application Example 5, except that the commercially available Direct Black 17 was used as is, and the same test was conducted. The excess amount was 1.5 g and the number of nozzles deviated by more than 200 μm was 9. It was individual.

Application Example 6 Hydrochloric acid was added to a 20% aqueous solution of Direct Black 19 (200-L, manufactured by Orient) until the pH reached approximately 1.0 to precipitate the dye. After the precipitated dye was separated by filtration, the precipitate was washed five times with purified water to remove residual sodium chloride and hydrochloric acid.
After washing with water, the dye was heated and dried in a vacuum. After drying, make a 20% by weight aqueous dispersion of the dye and gradually add lithium hydroxide while stirring well to adjust the pH of the liquid.
Adjusted to 10.5. The lithium salt solution of this dye was dried in the same manner as in Example 1, and
A solid lithium salt of the dye was obtained.

Using this dye, an ink was prepared according to the following recipe and heated and stirred at 60°C for 5 hours.

Purified dye (Direct Black 19) 6% Glycerin 7% Diethylene glycol 13% Triethylene glycol 10% Pentachlorphenol sodium salt 0.05% Nonionic dye solubilizer Carazol TG (Daiichi Kogyo Seiyaku) 0.2% Sodium ethylenediaminetetraacetate 0.05% Water 63.7% When this ink was used in the same manner as in Application Example 1 to evaluate clogging using a printer, the excess amount of ink was 165g, and there was no case where the ejection position was shifted by more than 200μm before and after leaving it. Nakatsuta.

Comparative Example 6 An ink was prepared using the same recipe as in Application Example 6, except that a solid dye obtained by drying a lithium salt aqueous solution of the dye before benzyl alcohol extraction was used, and the same test was conducted. The excess amount was 2.6g, and the injection position was 200μm before and after leaving it.
There were three items that were off.

Effects The recording liquid using the black direct azo dye containing no impurity components according to the present invention not only satisfies all the various conditions required for recording, but is also effective in preventing clogging and improving stability in the jetting direction, especially in inkjet systems. There is. In addition, although over-processing of ink is essential for ink production, the recording liquid according to the present invention hardly causes clogging of the filter, so the life of the filter is extended (approximately 50% compared to when no extraction operation is performed). ~10,000 times), improved manufacturability and lower costs.

Claims (1)

[Claims] 1 Direct liquid phase-liquid extraction operation between the azo dye solution and benzyl alcohol alone or with a mixture of other solvents that are compatible with benzyl alcohol but not substantially compatible with water. A direct azo dye characterized by removing impurities by transferring them to a liquid phase containing .