JPH04183761A - Ink - Google Patents

Abstract

PURPOSE:To obtain ink useful for ink jet printer, having excellent printing speed, fixation properties and shelf stability, comprising a nonionic acetylene glycol surfactant and a specific glycol ether in a specific ratio. CONSTITUTION:In ink comprising at least water-soluble dye, one or several kinds of polyhydric alcohols such as glycerol, a nonionic acetylene glycol surfactant and water, the objective ink contains 0.07-5wt.% nonionic acetylene glycol surfactant and 5-25wt.% glycol ether such as ethylene glycol monobutyl ether having <=1mmHg vapor pressure at 20-25 deg.C normal temperature and <=35dyn/cm surface tension.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to printing inks, and more particularly to the composition of printing inks used in on-demand inkjet printers.

[Prior Art] Inks used in inkjet recording methods are required to satisfy the following conditions in order to obtain good recording.

(1) Physical property values such as viscosity, surface tension, electrolyte, density, etc. are within appropriate ranges depending on the ink ejection characteristics of the recording head.

(2) The above physical property values do not change or solid content does not precipitate during long-term storage or long-term use.

(3) The nozzles of the recording head should not become clogged during the recording pause.

(4) Necessary print density can be obtained during recording.

(5) The ink should be quickly fixed on the recording material and there should be no irregular bleeding in the dots.

Furthermore, in order to increase the versatility of the printer, it is required that the following conditions be satisfied.

(6) To improve the ink ejection responsiveness of the head so that the printing speed of the printer can be increased.

(7) Low running costs.

Conventionally, attempts have been made to satisfy the above conditions using the following means.

That is, 1) If the ink ejection nozzles of the recording head are clogged or have some kind of deposit, the reliability of printing will be impaired. To solve this problem, polyhydric alcohol solvents with low vapor pressure and hygroscopicity are used as wetting agents to prevent clogging. However, it is known that the amount of wetting agent added is proportional to the viscosity of the ink, and if a large amount of wetting agent is used to prevent clogging, the viscosity will increase and the physical properties will no longer be within the range suitable for an inkjet ink.

2) In order to obtain the clear print density necessary for recording,
A common practice is to increase the addition of dye. However, if a large amount of dye, which is a solid content, is bleached, a large amount of precipitation occurs during evaporation drying of the ink. Since precipitation at the ink ejecting area can clog the nozzle, it is necessary to add an appropriate amount of dye.

3) In order to quickly fix the ink to the recording material, it is necessary to use water-soluble rosins such as hexylene glycol, dipro, and pyrene glycol that completely dissolve the rosin, as shown in JP-A No. 2-158669. A method containing an organic solvent has been adopted. It is effective in the case of acidic paper that uses Shikaji rosin as a sizing agent, but the effect is small in the case of acid-free paper, which has been used in increasing amounts recently.

4) Ink ejection responsiveness is determined by the frequency characteristics of the head, and the frequency increases as the ink particle diameter per dot becomes smaller. That is, if the ink particle diameter per dot is small, the size of the r cavity j, which is a pressure chamber for ejecting ink, can be made small. If the size of the cavity is small, the natural frequency of the recording head will be large, and the frequency heat will be large. If the ink particle diameter per dot is small, the number of characters that can be printed with the same amount of ink will increase, resulting in lower running costs.

[Problems and objects to be solved by the invention] However, in the prior art described above, means have been developed to satisfy the required performance individually, but when they are combined, all or a plurality of required performances can be satisfied. A means to simultaneously satisfy both has not yet been developed. Therefore, the object of the present invention is to fully satisfy all of the above conditions, to speed up the fixing performance not only to acidic paper, but also to neutral paper using an alkyl ketene dimer as a sizing agent, and to improve the fixing performance per dot. An object of the present invention is to provide an ink whose particle size can be reduced.

[Means for Solving the Problems] The ink of the present invention is an ink containing at least a water-soluble dye, one or more polyhydric alcohols, a nonionic acetylene glycol surfactant, and water. Activator content is 0.07
~5% by weight, and the vapor pressure at room temperature of 20 to 25°C is 1 mmHg or less and the surface tension is 35 d yn /
It is characterized by containing 5 to 25% by weight of glycol ethers having a molecular weight of 5 to 25% by weight.

[Function] Improvements were made to inkjet inks for the purpose of simultaneously satisfying the various required performances as described above. As a result, the ink contains glycol ethers, which have a low vapor pressure of 1 mmHg or less at 20 to 25°C, are extremely difficult to evaporate, and have a surface tension of 35 dyn/cm or less, and a nonionic acetylene glycol surfactant. By including it together, it is difficult to evaporate and dry, and the fixing speed on all types of paper is high.
We were able to develop an ink with a small ink particle size per dot, and therefore a small ink weight.

[Example] Next, the present invention will be explained in detail by giving examples and comparative examples.

Examples of the glycol ether of the present invention include ethylene glycol monobutyl ether, dipropylene glycol monoethyl ether, diethylene glycol monobutyl ether, and dipropylene glycol monomethyl ether.

Table 1 shows the vapor pressure and surface tension of these glycol ethers at room temperature, but glycol ethers other than those listed in this table may be used as long as they meet the required characteristics of vapor pressure and surface tension. do not have.

Ink compositions and manufacturing methods of Examples of the present invention using diethylene glycol monobutyl ether are shown below, but these Examples do not limit the present invention.

Surfynol 465, Surfynol TG, Surfynol 10 described in the following Examples or Comparative Examples
4 is a typical nonionic acetylene glycol surfactant, manufactured by Air Products an
Manufactured by d Chemicals.

Examples 1 to 8 After mixing the following ingredients and sufficiently stirring to dissolve them,
An ink was prepared by filtration using a membrane filter with a hole diameter of 0.8 μm.

□ Below margin □ Tan's A C,1, Direct Black 168 3 parts by weight Glycerin 10 parts by weight Surfynol 465 (surfactant, trade name) 3 parts by weight Water 70 parts by weight Tatsu's B C,1, Direct Black 168 3 parts by weight Glycerin 10 parts by weight Surfynol 465 (surfactant, trade name) 5 parts by weight Water 70 parts by weight
C, 1, Direct Black 168 3 parts by weight Glycerin 10 parts by weight Surfynol TG (surfactant, trade name) 0.5 parts by weight Water 70 parts by weight
N's D C,1, Direct Black 168 3 parts by weight Glycerin 10 parts by weight Surfynol 104 (surfactant, trade name) 0.12 parts by weight Water 70 parts by weight Tsuku's A C,1, Direct Black 168 3 parts by weight 1 part glycerin 10 parts by weight Surfynol 465 (surfactant, trade name) 12 parts by weight Water 70 parts by weight
B C,L Direct Black 168 3 parts by weight Glycerin 10 parts by weight Surfynol 104 (surfactant, trade name) 0.05 parts by weight Water 70 parts by weight Ink composition of Example 1 Ink composition example of Example 2 Ink composition of Example 3 Ink composition of Example 4 Ink composition of Example 5 Ink composition of Example 7 Ink composition of Example 8 Ink composition of Comparative example 1 Ink composition of Comparative example 2 Ink composition of Comparative example 3 Ink Composition Comparative Example 4 Ink Composition Comparative Example 5 Ink Composition Comparative Example 6 Ink Composition Comparative Example 7 Ink Composition Usage Example On-demand inkjet printer HG-SOO
(manufactured by Seiko Epson) Examples 1 to 8 and Comparative Example 1
Tables 2 and 3 show the evaluation of ink weight per dot, ink fixation speed, nozzle clogging, and viscosity measurement results when printing was performed with ink filled with No. 8 to 8.

The evaluation method and evaluation criteria are as follows.

1) Average dot diameter per dot Commercially available general high-quality paper was used as the recording material. A clearly distinguishable single dot is printed on this paper. From this printing result, the diameter of the dots is observed using a microscope, and the diameters of the dots are measured by dividing the dots into the printing direction of the printer and the direction perpendicular to this direction. Two diameter lengths are measured for one dot, and the average is taken as the average dot diameter.

2) Ink weight per dot Measure the number of dots used for printing and the weight of ink consumed, and calculate the ink weight per dot from ink weight ÷ number of dots.

In conjunction with the results of 1), the weight of ink required to obtain a certain size of dot diameter is determined and compared.

3) Ink fixation speed After printing, rub the printed surface with another piece of paper and measure the time until the ink stops rubbing with a stopwatch.

The papers used were neutral paper Xerox paper (manufactured by Fuji Xerox), acidic paper 4024 paper 3R721 (manufactured by XEROX), register paper (manufactured by Daishowa Paper), and 45 kg high-quality paper (manufactured by Jujo Paper). The criteria for evaluation were as follows.

■: Drying time 1 second or less O: Drying time 10 seconds or less △: Drying time 1 minute or less ×: Drying time 1 minute or more 4) Inkjet printer HG-800 filled with nozzle clogged ink
Remove only the recording head from the printer and leave it in a 40°C environment for one week. Even if the nozzles of the recording head become clogged after one week, we will evaluate whether the initial print quality can be reproduced by sucking ink from the nozzles with the pump attached to the HG-800. The criteria for evaluation were as follows.

■ = Initial print quality can be reproduced without suction or with one suction.

O: Initial print quality can be reproduced with 2 to 3 suctions.

The initial print quality can be reproduced by 614 to 5 suctions.

×: Initial print quality cannot be reproduced even after 6 or more suctions.

5) Viscosity of ink The viscosity of the ink is measured using a digital display type B-type viscometer (manufactured by Tokyo Keiki). (Measurement temperature: 20℃) □ Below Margin □ Table 1 (Physical properties) Table 2 (Evaluation results) Table 2 (Evaluation results) Continued Table 2 (Evaluation results) Continued □ Below Margin Table 3 (Evaluation results) □ Below Margin Table 3 (Evaluation Results) Continued □ Below Margin Table 3 (Evaluation Results) Continued □ Below Margin Table 3 (Evaluation Results) Continued □ Below Margin [Effects of the Invention] As described above, the present invention However, in an ink containing at least a water-soluble dye, a polyhydric alcohol, a nonionic acetylene glycol surfactant, and water, 5 to 25% by weight of glycol ethers and 0.07 to 5% by weight of nonionic acetylene glycol surfactant. By containing it, it is possible to not only have good performance characteristics for inkjet printers but also to obtain high quality printing. Furthermore, since the weight of ink used to form one dot can be reduced, running costs can be reduced and printing speed can be increased.

that's all

Claims (1)

[Claims] In the ink containing at least a water-soluble dye, one or more polyhydric alcohols, a nonionic acetylene glycol surfactant, and water, the content of the nonionic acetylene glycol surfactant is 0.07 to 5% by weight. ,
An ink containing 5 to 25% by weight of glycol ethers having a vapor pressure of 1 mmHg or less and a surface tension of 35 dyn/cm or less at room temperature of 20 to 25°C.