JP2953041B2 - ink - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a printing ink, and more particularly to a composition of a printing ink used in an on-demand type ink jet printer.

[Related Art] Ink used in an ink jet recording method is required to satisfy the following conditions in order to obtain good recording.

(1) Physical properties such as viscosity, surface tension, electrolyticity, and density are within appropriate ranges according to the ink ejection characteristics of the recording head.

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

(3) The nozzles of the recording head are not clogged during recording suspension.

(4) A print density required for recording can be obtained.

(5) The ink is quickly fixed to the recording material, and the dots do not have irregular bleeding.

Further, in order to improve the versatility of the printer, it is required to satisfy the following conditions.

(6) Improving the ink ejection response of the head so that the recording speed of the printer can be increased.

(7) The running cost is low.

Conventionally, the following conditions have been used to satisfy the above conditions.

1) If the ink discharge nozzles of the recording head are clogged or have any deposits, the printing reliability is impaired. To solve this problem, clogging is prevented by using a polyhydric alcohol solvent having a low vapor pressure and hygroscopicity as a wetting agent. However, it is known that the amount of addition and the viscosity of the ink are proportional. If a large amount of a wetting agent is used to prevent clogging, the viscosity will increase and the ink will not fall within the range of physical properties suitable for an inkjet ink.

2) To obtain a clear print density necessary for recording,
It is common practice to add more dye. However, when the amount of the solid content dye is large, the amount of precipitation increases in the evaporation and drying of the ink. Since precipitation at the ink discharge portion causes nozzle clogging, an appropriate amount of dye must be added.

3) In order to quickly fix the ink to the recording material, for example, as shown in JP-A-2-158669,
A method containing a water-soluble organic solvent that completely dissolves rosin such as hexylene glycol and dipropylene glycol has been adopted. However, although the effect is obtained in the case of acidic paper using rosin as a sizing agent, the effect is small in the case of neutral paper, which has recently been used in a large amount.

4) The ink ejection response is determined by the frequency characteristics of the head, but the frequency increases if the ink particle diameter per dot is small. That is, when the ink particle diameter per dot is small, the size of the "cavity" which is a pressure chamber for discharging ink can be reduced. When the size of the cavity is small, the natural frequency of the recording head increases, and the frequency increases. If the ink particle diameter per dot is small, the number of characters that can be printed with the same amount of ink further increases, so that the running cost is reduced.

[Problems and Objects to be Solved by the Invention] However, in the above-described conventional technology, means for individually satisfying required performances have been developed, but all or a plurality of required performances are integrated. No means have yet been developed to satisfy at the same time. Accordingly, an object of the present invention is to improve the fixability to neutral paper using not only acidic paper but also alkyl ketene dimer as a sizing agent, while sufficiently satisfying all conditions of steam. An object of the present invention is to provide an ink capable of reducing the ink particle diameter.

[Means for Solving the Problems] The ink of the present invention is an ink containing at least a water-soluble dye, one or several polyhydric alcohols, a nonionic acetylene glycol surfactant, and water. Activator content is 0.07-
5% by weight and a vapor pressure of 1 mmH at a normal temperature of 20 to 25 ° C.
It is characterized in that it contains 5 to 25% by weight of glycols having a surface tension of 35 dyn / cm or less and a dipropylene glycol or hexylene glycol as the glycols.

[Operation] The ink-jet ink was improved for the purpose of simultaneously satisfying the various required performances as described above. As a result, it is a kind of glycols in the ink and the vapor pressure at 20 ° C is less than 0.01 mmHg and is very difficult to evaporate, and the surface tension is 32 dyn / cm and dipropylene glycol or vapor pressure at 20 ° C Is as small as 0.02mmHg,
Hexylene glycol whose surface tension is as small as 27 dyn / cm,
Incorporation of a nonionic acelenium glycol surfactant also makes it difficult to evaporate and dry, develops a high fixing speed to all papers, and develops an ink with a small ink particle diameter per dot and therefore a small ink weight. did it.

[Examples] Next, the present invention will be described in detail with reference to Examples and Comparative Examples.

Hereinafter, the ink composition and the manufacturing method of the examples of the present invention will be described, but the examples do not limit the present invention. Glycols other than dipropylene glycol and hexylene glycol may be used as long as they satisfy the required characteristics of vapor pressure and surface tension.

Surfynol 465 and Surfynol 104 described in the following Examples or Comparative Examples are representative of nonionic acetylene glycol surfactants,
Manufactured by ducts and Chemicals.

Examples 1 to 8 The following components were mixed, sufficiently stirred and dissolved, and then filtered using a membrane filter having a hole diameter of 0.8 μm to prepare an ink.

Basic composition of the implemented ink A CI 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 Basic composition of the implemented ink B CI 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 Basic composition of ink used C CI Direct Black 168 3 parts by weight Glycerin 10 parts by weight Surfinol 104 (surfactant, trade name) 0.12 parts by weight Water 70 parts by weight Basic composition of compared ink A CI Direct Black 168 3 parts by weight Glycerin 10 parts by weight Surfynol 465 (surfactant, trade name) 12 parts by weight Water 70 parts by weight Basic composition of compared ink B CI Direct Black 168 3 parts by weight Glycerin 10 parts by weight Surfynol 104 (surfactant, trade name) 0.05 parts by weight Water 70 layers Basic composition C CI Direct Black 168 3 parts by weight Glycerin 10 parts by weight of water 70 parts by weight parts Comparative ink Application example On-demand type inkjet print HG-800
Examples 1 to 12 and Comparative Example 1 (manufactured by Seiko Epson)
Tables 1 and 2 show the ink weight per dot, the ink fixing speed, the evaluation of nozzle clogging, and the measurement results of the viscosity in the case of printing by filling the inks of Nos. 1 to 8 above.

 The evaluation method and evaluation criteria are as follows.

1) Average dot diameter per dot Commercially available high quality paper was used as a recording material. Printing on which one dot can be clearly distinguished is performed on this paper. The diameter of the dot is observed with a microscope from the printing result, and the dot is divided into a printing direction of the printer and a direction perpendicular thereto, and the dot diameter is measured. Two diameter lengths are measured for one dot, and the average is taken as the average dot diameter.

2) Ink weight per dot The number of dots used for printing and the weight of the consumed ink are measured, and the ink weight per dot is calculated from the ink weight / the number of dots.

In conjunction with the result of 1), the ink weight for obtaining a certain size dot diameter is obtained and compared.

3) Ink fixing speed After printing, the printing surface is rubbed with another paper and the time until the ink is no longer rubbed is measured with a stopwatch.

The paper used was neutral paper Xerox paper (Fuji Xerox), acid paper 4024 paper 3R721 (XEROX), register paper (Daishowa Paper) 45kg high-quality paper (Jujo Paper). The criteria were as follows.

◎: Fixing time 1 sec. Or less ○: Fixing time 10 sec. Or less △: Fixing time 1 min. Or less ×: Fixing time 1 min. And leave it at 40 ° C for 1 week. One week later, even if the nozzles of the recording head are clogged, it is evaluated whether or not the initial print quality can be reproduced by sucking ink from the nozzles with a pump attached to the HG-800. The criteria were as follows.

：: The initial print quality can be reproduced with no suction or one suction.

 :: The initial print quality can be reproduced with two or three suctions.

 Δ: The initial print quality can be reproduced with four to five suctions.

×: The initial print quality cannot be reproduced even if suction is performed six times or more.

5) Viscosity of ink The viscosity of the ink is measured with a digital display type B viscometer (manufactured by Tokyo Keiki). (Measurement temperature: 20 ℃) [Effect of the Invention] As described above, in an ink containing at least a water-soluble dye, a polyhydric alcohol, a nonionic acetylene glycol surfactant and water according to the present invention, dipropylene glycol or hexylene glycol or another glycol is used. Of 5 to 25% by weight of non-ionic acetylene glycol surfactant and 0.07 to 5% by weight of nonionic acetylene glycol surfactant, it is possible to obtain not only good properties for ink jet printer but also high quality printing. it can. Further, since the weight of the ink forming one dot can be reduced, the running cost can be reduced and the printing speed can be increased.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-4-183761 (JP, A) JP-A-4-183760 (JP, A) JP-A-4-175383 (JP, A) JP-A-4- 178475 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C09D 11/00-11/20

Claims (3)

(57) [Claims] 1. An ink containing at least a water-soluble dye, one or several polyhydric alcohols, a nonionic acetylene glycol surfactant and water, wherein the content of the nonionic acetylene glycol surfactant is 0.07 to 5% by weight. %
And an ink containing 5 to 25% by weight of a glycol having a vapor pressure of 1 mmHg or less at a normal temperature of 20 to 25 ° C. and a surface tension of 35 dyn / cm or less. 2. The ink according to claim 1, wherein diglycol is used as said glycol. 3. The ink according to claim 1, wherein hexylene glycol is used as said glycol.