JPS62164773A - Ink composition for use in ink jet - Google Patents

Abstract

PURPOSE:To obtain an ink compsn. for use in ink jet, which has excellent stability, drying resistance and re-dischargeability and hardly runs in colored parts, by blending an emulsion of a specified oily material with an ink mainly composed of water. CONSTITUTION:An ink compsn. is obtd. by blending 3-40wt% oily material insoluble in water and a coloring dye and having a b.p. of 170 deg.C or above in the form of an emulsion with an ink mainly composed of water. Examples of the dye are water-soluble dyes such as acid dyes, direct dyes, cationic dyes, reactive dyes, etc., and water-insoluble dyes such as disperse dyes, vat dyes, pigments, etc. When a water-insoluble dye is used, the effect of the compsn. is much remarkable. When a low-boiling oily material having a b.p. of lower than 170 deg.C is used, its drying rate is high and hence good resistance and re- dischargeability can not be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application!!P) The present invention relates to an inkjet ink composition, and more particularly to an inkjet ink composition that has excellent anti-drying properties and re-discharge properties.

(Prior Art) Conventionally, various additives have been added to inkjet inks to prevent nozzle clogging due to drying of the nozzle portion. In water-based inks, examples are known in which water-soluble glycols and glycol ethers with high boiling points are added. In water-based inks, water-soluble dyes such as acid dyes and direct dyes are usually used as coloring dyes, and the above-mentioned water-soluble glycols are mainly added to these systems. However, in this case, it is necessary to add a large amount of water-soluble glycols in order to obtain sufficient anti-drying ability, and adding this large amount delays the drying of the ink on the recording material such as paper, and also prevents smearing and bleeding. It has the disadvantage of being large.

On the other hand, when an inkjet is used to dye a fabric made of polyester fibers or the like, an ink containing a water-insoluble dye such as a disperse dye as the coloring dye is required. Unlike inks using water-soluble dyes, inks made by finely dispersing soluble dyes in water tend to coagulate when dried, and additives with excellent dispersion stability, drying prevention properties, and re-discharge properties have not yet been developed. unknown.

(Problems to be Solved by the Invention) An object of the present invention is to provide an inkjet ink composition that has excellent stability, anti-drying properties, and re-discharge properties, and has little bleeding in colored areas.

(Means for Solving the Problems) According to the present invention, an oily substance that is substantially insoluble in water and coloring dyes and has a boiling point of 170°C or higher is prepared as an emulsion into a water-based ink with a temperature of 3 to 40°C. % of the inkjet ink composition.

The dye component used in the ink composition of the present invention is not particularly limited, and includes water-soluble dyes such as acid dyes, direct dyes, cationic dyes, and reactive dyes, and water-insoluble dyes such as disperse dyes, vat dyes, and pigments. Use both.

However, the effects of the present invention are much more pronounced in systems using water-insoluble dyes.

In the present invention, an oily substance that is substantially insoluble in water and dyes and has a boiling point of 170°C or higher is blended into the ink as an emulsion, mainly to improve the drying prevention properties and re-discharge properties of the ink. is the essence. Here, the re-ejection property refers to the ability to draw normally without clogging the nozzle, disrupting the dots, or delaying the next print after printing is completed using an on-demand inkjet device.

It is necessary that the oily substance used in the present invention be substantially insoluble in water and dyes.

This means that the oily substance of the present invention is present in the ink as an emulsion and the emulsion oil droplets are substantially uncolored. When colored dyes are dissolved in oil droplets, oil dries at a slower rate than water, causing smearing and bleeding; however, in the present invention, where colored dyes are not dissolved in oily substances, oil does not bleed. The design itself has the effect of not bleeding.

Next, in the present invention, the boiling point of the oily substance is required to be 170°C or higher. Oily substances with a low boiling point of less than 170°C; dry very quickly and cannot obtain good drying prevention properties and re-dispensing properties.

The oily substance used in the present invention is not particularly limited as long as it satisfies the above conditions, but examples include (soybean oil, olive oil, tall oil, rapeseed oil, castor oil, which is liquid at room temperature,
Oils such as cottonseed oil, unsaturated fatty acids such as oleic acid, linoleic acid, and lylunic acid that are liquid at room temperature, and liquid fatty acid esters such as octyl butyrate, propyl caproate, hexyl carbtetraphosphate, ethyl caprylate, and methyl oleate. , higher alcohols such as octatool, decanol, lauryl alcohol, myristyl alcohol, tetralin,
These include hydrocarbons such as decalin, kerosene, and liquid paraffin.

Some of these oily substances can be added to oil-based inks, for example, as disclosed in Japanese Patent Application Laid-Open No. 49-50935.5.
0-84311, etc., but in the present invention, it is essential that the oil be emulsified in an aqueous medium with substantially no dye present in the oil.
This is essentially different from conventional usage.

Various known emulsifiers are appropriately used to emulsify these oily substances in the aqueous ink medium. Examples of anionic emulsifiers include fatty acid soaps, higher alcohol sulfate ester salts, alkylbenzene sulfonates, and sodium dioctyl sulfosuccinate; examples of nonionic emulsifiers include:
Polyethylene glycol alkyl ether, polyethylene glycol alkyl phenyl ether, polyethylene glycol fatty acid ester, polypropylene glycol polyethylene glycol ether, polyoxyethylene sorbitan fatty acid ester, etc., and nonionic anionic ones include polyoxyethylene alkylphenyl ether sulfate, etc. can give. The amount of emulsifier used is usually 2 to 50% by weight based on the oily substance.

In the present invention, the amount of the emulsion of the oily substance contained in the ink is 3 to 40% by weight. If it is less than 3%, a sufficient drying prevention effect cannot be obtained, and if it is more than 40%, the stability of the ink deteriorates, the emulsion thickens, and the inkjet flight properties deteriorate. A particularly preferred range is 5 to 30%. Even within these ranges, if the emulsion ink becomes a thickened cream, it becomes impossible to print the ink on an inkjet jet. In order to avoid these problems, it is desirable to select an emulsifier so that the viscosity of the emulsion ink is 50 ep or less, particularly 20 ep or less.

As described above, in the ink composition of the present invention, since the anti-drying agent exists as an emulsion separately from the colored layer, it has excellent anti-drying properties and re-discharge properties, but is superior to conventional homogeneous inks. The effect is that the phenomenon of bleeding and smearing of colored areas caused by slow drying on the recording material is small.

In addition to water, dyes, oily substances, and emulsifiers, the inkjet ink composition of the present invention may optionally contain various known additives such as antifungal agents, chelating agents, pH adjusters, and emulsion stabilizers. It is possible to add water-soluble polymers to prevent bleeding.

(Example) Next, the present invention will be explained based on examples.

An emulsion was prepared using a homomixer using olein Hza part, 3 parts of polypropylene glycol polyethylene glycol ether (Pluronic, F-108 manufactured by Asahi Denka ■), and 57 parts of ion exchange water. Terasil Black X-R (CIIIA-
A disperse dye ink for inkjet was prepared by blending GEI with 20 parts of liquid disperse dye (manufactured by Y).

For comparison, Terasil Black
-R20 parts, 20 parts of water-soluble glycol diethylene glycol in 60 parts of ion-exchanged water (Comparative Example 1), and 20 parts of glycol ether ethyl diglycol (Comparative M2)
were blended to prepare a disperse dye ink for inkjet use. These inks were filtered through a 5μ cut filter to determine the dispersibility of the inks (see Table 1).

After degassing under reduced pressure using this ink, printing was performed under the following inkjet conditions.

Method: On-demand method Nozzle diameter: 60μ Applied voltage: 50V In order to check the drying performance and ink clogging at the nozzle tip of the inkjet printer, the ink-leaving time was measured. The results are shown in Table 1.

Table 1 * Dispersibility: Dye dispersion rate T (%) calculated from the following formula
This is an evaluation method in which the results are evaluated in five stages as shown in Table 2.

Table 2 ** Allowable ink leaving time: 1. When the nozzle was left without a cap, the possible leaving time during which the ink could be ejected without drying or clogging was measured.

As shown in Table 2, the oleic acid of the present invention allowed ink to be ejected without causing ink clogging even when the nozzle was left without a cap for 60 minutes or more, and also had good ink dispersibility.

On the other hand, in the diethylene glycol of Comparative Example 1, almost no anti-drying agent was observed. Further, in the case of ethyl diglycol of Comparative Example 2, significant dispersion destruction and dye aggregation of the disperse dye occurred, and it could not be used as an ink.

(Effects of the Invention) The ink composition for inkjet etching of the present invention has extremely excellent anti-drying properties and excellent dispersion stability.
This enables smooth inkjet operation without troubles due to ink clogging, and has great practical value.

Patent Applicant: Higashi Shikaisha, Ltd., -.

Claims (1)

[Claims] An inkjet ink composition comprising 3 to 40% by weight of an oily substance that is substantially insoluble in water and colored dyes and has a boiling point of 170° C. or higher in a water-based ink as an emulsion.