JP2675868B2 - Inkjet recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is applicable not only to designated paper specially adjusted for ink jet but also to other copy paper, report paper, bond paper, continuous slip paper, etc. The present invention relates to an ink jet recording method capable of high-definition and high-quality recording even on office paper or plain paper generally used at home.

[Conventional technology]

Some ink jet printers that use thermal energy to eject ink have already been put into practical use as products. In recent years, the recording head installed in the printer has become much smaller and simpler in structure than before, making it ideal for high-speed, high-density recording, colorization, and low noise generation. Has been attracting attention as a means for providing various recording devices.

[Problems to be solved by the invention]

However, in order to perform high-density recording of 300 dpi or more, when a high density orifice is used as the recording head, the increase in the number of heating elements causes the temperature increase of the recording head itself during ejection, compared to the conventional recording head. Also, the thermal stability of the ink components supplied to the recording head cannot be ignored. In other words, if the ink components, especially the dye, cannot be held stable in dissolution at high temperatures, the high heat generated during foaming of the heating element causes the dye to decompose, causing deposits on the surface of the heating element. It will have a big impact.

In addition, when a recording head that is highly densely aligned is used, the droplet diameter of the ejected ink is smaller than when using a conventional recording head, so that the bleeding of ink dots on the recording paper is reduced. However, there arises a problem that sufficient dots cannot be obtained to obtain high image quality.

This problem is particularly noticeable when printing on plain paper whose bleeding cannot be controlled.

Therefore, an object of the present invention is to provide an ink jet recording method capable of always performing stable ejection even in high-density recording, obtaining a dot of a desired size, and forming a high-definition and high-quality image. It is in.

[Means and actions for solving the problems]

 The above object is achieved by the present invention described below.

That is, the present invention is an ink jet recording method in which ink is ejected using thermal energy, and the ink is adhered to a recording paper at a recording density of 300 dpi (dots / inch) or more for recording, and the ink is a recording agent. , Urea, an aliphatic monohydric alcohol, and water.

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

The recording agent used in the present invention is a water-soluble acid dye,
Direct dyes, basic dyes, reactive dyes and the like are suitable.

Particularly preferred dyes include (X in the formula represents Na or Li.) CI Direct Yellow 86 CI Assisted Yellow 23 CI Direct Red 227 CI Direct Blue 199 CI Direct Blue 86 is a combination of one or more selected from two or more. .

Such dyes are particularly preferable because they are stable for a long time under a high temperature condition due to the interaction with urea, and have a good hue, sufficient density and saturation.

According to the present invention, not only high density recording is easy, but also urea contained in the ink enhances the dissolution stability of the dye under high temperature conditions, so that foreign matter may be deposited on the surface of the heating element. It shows excellent ejection stability without exception, and when urea and an aliphatic monohydric alcohol are used together, ink bleeding on recording paper is large and dots with a shape close to a perfect circle can be obtained, resulting in high definition. This enables high-quality ink jet recording.

〔Example〕

Next, the present invention will be specifically described with reference to Examples and Comparative Examples. In the text, parts or% are based on weight.

Examples 1 to 8 and Comparative Examples 1 to 3 The following components were mixed and sufficiently stirred to dissolve the pore size.
Eleven kinds of ink were prepared by pressure filtration with a 0.45 μm fluoropore filter (Sumitomo Electric Industries, Ltd.).

<Ink composition of Example 1> Dye (X: Li) of specification example No. 2 1.5 parts Dye (X: Li) of specification example No. 3 1 part Urea 20 parts Glycerin 10 parts Methanol 8 parts Water 59.5 parts <Ink composition of Example 2> Dye (X: Na) of No. 4 in the specification example 0.8 part CI Direct Red 227 0.8 part CI Direct Yellow 86 0.5 part Urea 4.5 parts Ethanol 4.5 parts Water 88.9 parts <Example 3 Ink composition> Dye (X: Na) No. 4 in the specification example 0.25 parts CI Direct Blue 199 1.5 parts CI Direct Red 227 0.25 parts Urea 5 parts Ethanol 5 parts Water 88 parts <Ink composition of Example 4> CI Direct Yellow 86 0.7 parts CI Direct Blue 199 1.3 parts Urea 5 parts Ethanol 4.5 parts Water 88.5 parts <Ink composition of Example 5> CI Direct Blue 86 3 parts Urea 15 parts Diethylene glycol 8 parts Isopropanol 15 parts Score roll # 900 (surfactant ) 0.1 parts Water 58.9 parts <Actual Ink composition of Example 6> Dye (X: Na) of No. 1 in the specification example 3 parts Urea 5 parts Ethanol 5 parts Water 87 parts <Ink composition of Example 7> CI Acid Yellow 23 4 parts Urea 10 parts Tri Ethylene glycol 10 parts Methanol 6 parts Water 70 parts <Ink composition of Example 8> Specification example No. 2 dye (X: Li) 0.9 part Specification example No. 3 dye (X: Li) 0.6 part Exemplified No. 1 dye (X: Na) 1.5 parts Urea 5 parts Ethanol 5 parts Water 87 parts <Ink composition of Comparative Example 1> A comparative ink composition using 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> A comparative ink composition obtained by removing only methanol from the ink composition of Example 7.

Next, using the above 11 kinds of ink, 360d shown in FIG.
Pi recording head (nozzle pitch 70.5 μm, number of nozzles 64)
And the 400 dpi recording head shown in Fig. 2 (nozzle pitch 63.5
μm, number of nozzles 256), print on high quality paper,
The evaluation was performed. Table 1 shows the results.

[Advantages of the Invention] As described above, according to the present invention, since the thermal stability of the recording liquid can be improved with the increase in the density of the ink ejection ports, the thermal decomposition of the dye on the surface of the heating element No deposition of foreign matter is observed and good ejection performance can be obtained.

Further, not only coated paper adjusted for ink jet but also plain paper for which bleeding cannot be adjusted can obtain excellent image quality with high resolution.

[Brief description of the drawings]

1 and 2 are perspective views of a head used for recording according to the present invention. 1,9: Heater board (silicon substrate) 2,10: Heating element 3,11: Nozzle 4,12: Ink liquid chamber 5,13: Ink supply port 6,14: Top plate 7,15: Discharge port 8,16 :wiring

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Claims (3)

(57) [Claims] 1. An ink jet recording method, wherein ink is ejected by utilizing thermal energy, and the ink is adhered to a recording paper at a recording density of 300 dpi (dots / inch) or more to perform recording. An ink jet recording method, comprising: urea, urea, an aliphatic monohydric alcohol, and water. 2. The ink jet recording method according to claim 1, wherein the recording paper is a high quality paper. 3. The ink jet recording method according to claim 1, wherein the urea is contained in the ink in the range of 1 to 20% by weight and the aliphatic monohydric alcohol is contained in the range of 1 to 10% by weight.