JPH02167772A - Ink jet recording - Google Patents

Abstract

PURPOSE:To make it possible to increase thermal stability of a recording liquid and prevent the settlement of foreign matter caused by pyrolysis of dye on the surface of a heat generating element following the high concentration of ink particles in an ink discharge hole and thus obtain satisfactory discharge performance by adding recording agent, urea, aliphatic monohydric alcohol and water to ink. CONSTITUTION:The preferable amount of urea contained in ink is 1 to 20% by weight, and the preferable amount of aliphatic monohydric alcohol is 1 to 10% by weight. Water-soluble acidic dye, direct dye, basic dye and reactive dye are recommended as recording agents. Especially more recommedable are one kind or two kinds or more of component dye selected from among C.I. direct yellow 86, C.I. acid yellow 23, C.I. direct red 227, C.I. direct blue 199 and C.I. direct blue 86. These dyes are stable under high temperature conditions for a long time due to their mutual action with urea. Furthermore, these dyes are particularly highly acceptable because of their satisfactory color, adequate density and chroma. Ink runs significantly on recording paper and approximately round dots are obtained by joint use of urea and aliphatic monohydric alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applicable not only to specified paper specially adjusted for inkjet use, but also to other types of copy paper.

The present invention relates to an inkjet recording method that enables high-definition, high-quality recording even on plain paper commonly used in offices and homes, such as report paper, bond paper, and continuous slip paper.

[Conventional technology]

Some inkjet printers that eject ink using thermal energy have already been put into practical use. In recent years, the recording heads installed in printers have become much smaller and simpler in structure than before, allowing for high-speed, high-density recording, color support, and
Furthermore, it is attracting attention as a means of providing an ideal recording device that generates little noise.

[Problem that the invention is trying to solve]

However, in order to perform high-density recording of 300 dpi or more, when using a recording head with high-density orifices, the temperature of the recording head itself during ejection increases due to the increase in the number of heating elements compared to conventional recording heads. The thermal stability of the ink components supplied to the recording head cannot be ignored either. In other words, if the dissolution stability of ink components, especially dyes, cannot be maintained at high temperatures, the dye will be decomposed by the high heat generated by the heating element when it foams, causing deposits on the surface of the heating element, which will prevent normal ink ejection. It will have a big impact.

Furthermore, when using a recording head with high-density orifices, the diameter of the ejected ink droplets is smaller than when using a conventional recording head, so the bleeding of ink dots on the recording paper is reduced. , a problem arises in that sufficient dots cannot be obtained to obtain high image quality.

This problem becomes particularly noticeable when printing on plain paper where bleeding cannot be controlled.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an inkjet recording method that can always perform stable ejection even during high-density recording, can consistently obtain dots of a desired size, and can form high-definition, high-quality images. There is a particular thing.

[Means and effects for solving the problems] The above objects are achieved by the present invention as described below.

That is, the present invention is an inkjet recording method for ejecting ink using thermal energy and recording at a recording density of 300 dpi or more, wherein the ink contains a recording agent, urea,
This is an inkjet recording method characterized by containing an aliphatic monohydric alcohol and water.

In the present invention, the amount of urea contained in the ink ranges from 1 to
20% by weight is preferred, and the amount of aliphatic monohydric alcohol is
1 to 10% by weight is preferred.

As the recording agent used in the present invention, water-soluble acid dyes, direct dyes, basic dyes, mono-reactive dyes, etc. are suitable.

Particularly preferred dyes include: l Shame4 Nα3 (In the formula, X represents Na or Li) C,I, Direct Yellow 86 C,1, Acid Yellow 23 C,1, Direct Red 227 C6! , Direct Blue 199 C0! , Direct Blue 86, or a combination of two or more thereof.

Such dyes are particularly preferred because they are stable for long periods of time under high temperature conditions due to interaction with urea, and have good hue, sufficient density and saturation.

According to the present invention, not only is high-density recording easy, but the urea contained in the ink increases the dissolution stability of the dye under high-temperature conditions, so that foreign matter may not be deposited on the surface of the heating element. In addition, by using urea and aliphatic monohydric alcohol in combination, the ink smudges significantly on the recording paper, and dots with a shape close to a perfect circle can be obtained, resulting in high-definition dots. This enables high-quality inkjet recording.

〔Example〕

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples. Note that parts and percentages in the text are based on weight.

Examples 1 to 8, Comparative Examples 1 to 3 The following components were mixed and thoroughly stirred until the pore size was 0.
．． Pressure filtration was performed using a 45 μm Fluorobor filter (manufactured by Sumitomo Electric Industries, Ltd.), and one type of ink was prepared.

<Ink composition of Example 1> Dye (X: Li) of Specification Example 2 (X: Li) 1.5
Dye (X: Li) 1 of Specification Example 3
Part urea 20 parts Glycerin 10 parts Methanol water <Ink composition of Example 2> Dye (X: Na) CHI of Nα4 illustrated in the specification, Direct Red 227 C,1, Direct Yellow 86 Urea Ethanol water <Ink composition of Example 3 > Specification exemplified Nα4 dye (X: Na) C,1, Direct Blue 199 C,1, Direct Red 227 Urea ethanol water <Ink composition of Example 4> C,1, Direct Yellow 86 C,1, Direct Blue 199 Urea 8 parts 59.5 parts 0.8 parts 0.8 parts 0.5 parts 4.5 parts 4.5 parts 88.9 parts 0.25 parts 1.5 parts 0.25 parts 5 parts 5 parts 88 parts 0.7 parts 1.3 parts 5 parts Ethanol water <Ink composition of Example 5> C, 1, Direct Blue 86 Urea Diethylene Glycol Isopropanol Score Roll #900 (Surfactant) Long <Ink composition of Example 6> Specification Exemplary Nαl dye (X: Na) Urea ethanol water <Ink composition of Example 7> C, 1, Acid Yellow 23 Urea triethylene glycol methanol water 4.5 parts 88.5 parts 3 parts 15 parts 8 parts 15 parts 0 .1 part 58.9 parts 3 parts 5 parts 87 parts 4 parts 10 parts 10 parts 6 parts 70 parts <Ink composition of Example 8> Specification example Nα2 (7) Dye (X: Li)
0.9 parts Dye (X: Li) exemplified in the specification Nα3
0.6 parts Specification example N (L 1 dye (X:
Na) 1.5 parts urea
5 parts ethanol
5 parts water
87 parts Ink composition of Comparative Example 1> Comparative ink composition obtained by removing urea and methanol from the ink composition of Example 7.

Ink Composition of Comparative Example 2> A comparative ink composition obtained by removing only urea from the ink composition of Example 7.

Ink Composition of Comparative Example 3> Comparative ink composition obtained by removing only methanol from the ink composition of Example 7.

Next, using the above 11 types of ink, 36 inks shown in FIG.
Printing was performed on high-quality paper using a 0 dpi recording head (nozzle pitch 70.5 μm, 64 nozzles per unit) and a 400 dpi recording head (nozzle pitch 63.5 μm, 256 nozzles per unit) shown in FIG. 2, and the results were evaluated. . The results are shown in Table 1.

Table 1 (Evaluation results) (When using a 360 dpi recording head) °1 ejection performance
°2 Image density Dot shape °1 Color development example 10
0 △ 0 40 0 o O 500△ 0 Comparative example 1 △ × △ 02 △ △
△ 0 30 × △ ○ (When using 400M, dpi recording 5 dots) 1 Ejection property 01 Image density Dot shape 088 Color development performance 10 0 △ 0 50 0 Δ 0 Comparative example 1 × × △ 02 × △
△ 0 30 × △ ○ 1 Ejection properties: Each recording liquid was filled into the head and ejected continuously for 48 hours at room temperature, and the degree of image quality deterioration after the test and the presence of foreign matter on the surface of the heating element Check for discharge failure due to deposition.

02 Image density: The difference in dot diameter was determined by measuring the image density.

0 Color development...Fill each recording liquid into the head and 4 at room temperature.
Continuous ejection was performed for 8 hours, and the rate of change in hue of the image after the test compared to that of the recording liquid before the test was measured.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to improve the thermal stability of the recording liquid as the density of the ink ejection ports becomes higher.
No deposition of foreign matter due to thermal decomposition of the dye on the surface of the heating element is observed, and good ejection performance can be obtained.

In addition, it is possible to obtain excellent image quality with high resolution not only on coated paper adjusted for inkjet printing but also on plain paper for which bleeding cannot be adjusted.

[Brief explanation of the drawing]

1 and 2 are perspective views of a head used for recording according to the present invention. l, 9: Heater board (silicon substrate) lO: ll: 12: 13: 14: 15: 16: Heating element nozzle ink liquid chamber ink supply port top plate discharge port wiring

Claims (1)

[Claims] (1) Discharge ink using thermal energy,
An inkjet recording method for recording at a recording density of 0 dpi (dots/inch) or more, wherein the ink contains a recording agent, urea, an aliphatic monohydric alcohol, and water.