JP2002060661A - Ink composition for jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition for jet printers which is excellent not only in safety and water resistance but also in re-dissolubility of a dried ink film, dissolution stability at printer use temperatures, and delivery stability through a nozzle. SOLUTION: This ink composition, at least containing a water-insoluble dye, a resin, and a 1-4C lower alcohol, is characterized in that it contains an ester solvent and does not substantially contain a ketone solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention has a lower toxicity than conventional inks, and is excellent in dissolution stability and ejection stability, especially at low temperatures (5 ° C. or lower) and ejection stability. The present invention relates to an ink composition for a jet printer having excellent water resistance of a print film on various recording materials such as metal, glass, and plastic.

[0002]

2. Description of the Related Art Printing by a jet printer is a method in which ink is ejected from a nozzle and adheres to a recording material. Since the nozzle and the recording material are in a non-contact state, Good printing can be performed on a curved surface or a surface having an irregular irregular shape. Various types of jet printers have been put into practical use, but the field of printing characters and the like on non-absorbing materials such as metals and plastics, for example, beverage cans and PEs
For printing the serial number on various food containers such as T bottles,
A continuous type (charge control type) printer using an ink containing various color materials, resins, organic solvents and the like is mainly used.

The properties required for an ink composition for a jet printer include: no safety and hygiene problems; excellent water resistance; re-dissolvability of a dried ink film; It is required that the dissolution stability in the liquid and the ejection stability from the nozzle be excellent. If the ink film dried and solidified at the ink discharge port becomes insoluble or hardly soluble in the solvent used for the ink, the discharge port becomes clogged and discharge becomes impossible. For this reason, it is necessary to select a material that can be easily dissolved in a solvent used for the ink as a solid substance such as a dye and a resin used for the ink. In addition, if the solid substance in the ink is insolubilized at the environmental temperature at which the printer is used, the physical properties of the ink, such as viscosity, change, and the ejection becomes unstable. It is necessary to select a material having good dissolution stability at the time. Further, in order to obtain a print film having good water resistance, it is necessary to select a material which is insoluble in water and has as low affinity as possible with water.

[0004] As jet inks for continuous type printers, there have been proposed many jet inks in which the main component of the organic solvent is methyl ethyl ketone and which has excellent adhesion to metals, glass and various plastics, and excellent water resistance of the printed film. ing. In an ink using a solvent containing methyl ethyl ketone as a main component, since the polarity of methyl ethyl ketone is moderate, it is relatively easy to select a material that satisfies re-dissolving property, dissolving stability, and water resistance of a printed film. Was. However, ketone solvents represented by methyl ethyl ketone are highly toxic and have problems in safety and health.

Although the toxicity is extremely low when a lower alcohol is used as a main component of an organic solvent for jet ink, if a dye having good solubility in the lower alcohol is used, such a dye has a relatively strong polarity and a hydrophilic property. Therefore, a material having sufficient adhesion and water resistance to various recording materials cannot be obtained. In addition, a dye obtained by using a dye having good solubility in a lower alcohol and further imparting water resistance has a problem that the dissolution stability and the ejection stability at a low temperature are inferior.

Accordingly, the present invention provides an ink composition for a jet printer which is excellent in safety, water resistance, re-dissolvability of a dried ink film, dissolution stability at a printer operating environment temperature, and ejection stability from a nozzle. The purpose is to provide things.

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have found that a lower alcohol is used as a main solvent, and a water-insoluble property essential for developing excellent water resistance of a printed film is obtained. By using an ester-based solvent instead of a ketone-based solvent as a dye dissolution aid, the solubility of the water-insoluble dye at low temperatures is improved, the ejection stability at low temperatures is improved, and various recording materials are used. The present inventors have found that an ink composition for a jet printer which has excellent adhesion and water resistance and is excellent in safety can be obtained, and has completed the present invention.

That is, the present invention relates to an ink composition for a jet printer containing at least a water-insoluble dye, a resin and a lower alcohol having 4 or less carbon atoms, wherein the ink composition contains an ester solvent and substantially contains a ketone solvent. The object of the present invention is to provide an ink composition for a jet printer, wherein the ink composition is not used. The present invention also provides an ink composition for a jet printer which does not contain a ketone-based solvent. The present invention also provides such an ink composition for a jet printer, wherein the ethanol content in a lower alcohol having 4 or less carbon atoms is 60% by weight or more. The present invention also provides such an ink composition for a jet printer, wherein the dye is a chromium complex dye. The present invention also provides such an ink composition for a jet printer, which is for a continuous recording system.

[0009]

Next, the present invention will be described in detail.
The water-insoluble dye referred to in the present invention is a dye used in the present invention that is soluble in lower alcohols having 4 or less carbon atoms and is substantially insoluble in water, and can further impart sufficient water resistance to a printed film. It has a low affinity for water. Such dyes soluble in lower alcohols having 4 or less carbon atoms and substantially insoluble in water include chromium complex dyes, nigrosine dyes, and salt-forming dyes (dye obtained by salting a basic dye and an acid dye). And the like, but a chromium complex dye is preferred from the viewpoints of water resistance and light resistance of the printed film. The chromium complex dye that is soluble in lower alcohols having 4 or less carbon atoms and is substantially insoluble in water is not particularly limited.
I. Solvent Black 27, 29, 43 and the like, and one or more of these can be used. The content of the water-insoluble dye in the ink composition is 4 to 10% by weight, particularly 6
~ 8% by weight is preferred.

In the present invention, the ester solvent used as a dissolution aid for the water-insoluble dye is preferably propylene glycol monoalkyl ether alkylate, carboxylate, alkoxycarboxylate, or the like. In the propylene glycol monoalkyl ether alkylate, the number of carbon atoms of the alkyl group constituting the monoalkyl ether and the number of carbon atoms of the alkyl group constituting the alkylate are preferably from 1 to 10, more preferably from 1 to 4. preferable. The alkyl group may be linear or branched. Among them, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, propylene glycol monomethyl ether propionate, propylene glycol monomethyl ether butyrate and the like are still more preferable, and propylene Glycol monomethyl ether acetate is particularly preferred.

In the carboxylic acid ester, the acyl group constituting the carboxylic acid residue preferably has 2 to 7 carbon atoms, and the group bonded to the oxygen atom is preferably an alkyl group having 1 to 6 carbon atoms. The acyl group may be linear or branched. Among them, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, amyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, butyl propionate, amyl propionate, hexyl propionate and the like are more preferable. Methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, butyl propionate, amyl propionate, hexyl propionate, etc. are even more preferred, and ethyl propionate is particularly preferred. The alkoxycarboxylic acid ester is one in which at least one hydrogen atom bonded to a carbon atom of a carboxylic acid residue is substituted with an alkoxy group, wherein the alkyl group constituting the alkoxy group has 1 to 6 carbon atoms, It is preferable that the acyl group constituting the carboxylic acid residue has 2 to 7 carbon atoms, and the group bonded to the oxygen atom is an alkyl group having 1 to 6 carbon atoms. The alkyl group may be linear or branched. Of these, methyl methoxypropionate, ethyl ethoxypropionate, methyl propoxypropionate, methyl butoxypropionate, ethyl isobutoxypropionate, pentyl pentyloxypropionate, and hexyloxypropionate are more preferable, and ethyl ethoxypropionate is more preferable. Particularly preferred. In the present invention, one or two of these ester solvents are used.
More than one species can be used. The content of these ester solvents is preferably at least 50% by weight, more preferably at least 60% by weight, based on the content of the water-insoluble dye in view of the stability of the water-insoluble dye at low temperatures.

The lower alcohol used in the present invention has 4 or less carbon atoms, and specifically includes methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol and tertiary alcohol.
t-butanol. In the present invention, these can be used alone or in combination of two or more. Among them, the ethanol content in the lower alcohol having 4 or more carbon atoms is preferably 60% by weight or more, more preferably 70% by weight or more, and particularly preferably 80% by weight or more. Further, the content of the lower alcohol having 4 or more carbon atoms in the ink composition for a jet printer of the present invention is preferably 60% by weight or more. Furthermore, when used for a continuous jet printer ink, the ethanol content in the ink composition for a jet printer is preferably 60% by weight or more, particularly 65% by weight or more in order to increase the electric conductivity of the ink. preferable. At this time, the concentration can be adjusted by adding purified water. Also, a mixed solvent containing 85.5% of ethanol is sold under the name of denatured alcohol,
This can also be used.

As the binder resin used in the present invention, any resin can be used as long as it is soluble in the lower alcohol having 4 or less carbon atoms and has good dissolution stability at low temperatures. Specific examples include, but are not limited to, styrene acrylic resin, styrene maleic acid resin, silicone resin, phenol resin, terpene phenol resin, polyester resin, rosin maleic resin, ketone resin, cellulose resin, rosin ester, and the like. Not something.
These resins can be used alone or in combination of two or more. The content of these resins in the ink composition for a jet printer of the present invention is 5 from the viewpoint of imparting an appropriate viscosity to the ink and imparting film properties such as good abrasion resistance and water resistance to a printed film. -15% by weight, especially 7-10% by weight is preferred.

The ink composition for a jet printer of the present invention contains the water-insoluble dye, the resin, the lower alcohol having 4 or less carbon atoms and the ester solvent, and substantially does not contain the ketone solvent. . "Substantially not contained" means that it is acceptable to include it to such an extent that it does not pose a problem on human health and safety. In the present invention, the ketone-based solvent is used in accordance with the revised Occupational Safety and Health Act (April 1, 2000).
1/1) of 1% that is mandatory for entry into MSDS
It is preferably 0, that is, 0.1% or less, and particularly preferably not contained at all. If it does not substantially contain a ketone solvent, it has low toxicity, dissolution stability,
An ink composition for a jet printer having excellent ejection stability and water resistance of a print film can be obtained.

In order to improve the print film performance such as abrasion resistance, transfer resistance and scratch resistance of an ink film printed using the ink composition for a jet printer of the present invention,
A compound such as a silicone compound or a fluorine compound which is soluble in the mixed solvent used in the present invention can be added to the ink composition for a jet printer. Examples of the silicone compound include silicone oil, modified silicone oil, and silicone resin. Specifically, KF-56 (silicone oil) manufactured by Shin-Etsu Chemical Co., Ltd., TSF-410 (higher fatty acid-modified silicone oil) manufactured by Toshiba Silicone, TSF-4446, 446
0 (polyether-modified silicone oil), TSF-4
710 (amino-modified silicone oil) and KP-316, 360A (silicone resin) manufactured by Shin-Etsu Chemical Co., Ltd., but are not limited thereto. In the present invention, these can be used alone or in combination of two or more.

Examples of the fluorine compound include a fluorine surfactant. Specifically, Megafac F-470, F-173, F-17 manufactured by Dainippon Ink and Chemicals, Inc.
7 and the like, but are not limited thereto. In the present invention, these can be used alone or in combination of two or more. Further, it can be used in combination with the above-mentioned silicone compound.

The ink composition for a jet printer of the present invention is particularly preferably used for a continuous recording system. In this case, if necessary, an inorganic salt such as lithium nitrate and sodium thiocyanate, and an organic salt such as a quaternary ammonium salt can be added as a conductivity-imparting agent in order to increase the electric conductivity of the ink.

The ink composition for a jet printer of the present invention can be prepared by mixing the raw materials, sufficiently stirring and dissolving, and optionally filtering.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples. In the following description, "parts" indicates parts by weight.

Example 1 An ink composition for a continuous recording type jet printer was prepared according to the following composition ratio. C. I. Solvent Black 29 6.0 parts John Krill 68 6.5 parts (Styrene acrylic resin manufactured by Johnson Polymer) YP-902 1.5 parts (terpene phenol resin manufactured by Yashara Chemical) Propylene glycol monomethyl ether acetate 6.0 parts TSF-4460 2 parts (Toshiba silicone polyether-modified silicone oil) KF-56 0.1 part (Shin-Etsu Chemical silicone oil) Lithium nitrate 0.5 part Ethanol 79.2 parts That is, the above mixture was sufficiently stirred and dissolved. Thereafter, this solution was filtered with a 0.5 μm membrane filter to obtain an ink composition for a continuous type jet printer.

Example 2 An ink composition for a continuous recording type jet printer was prepared according to the following mixing ratio. C. I. Solvent Black 27 7.0 parts GAX-12-250 5.0 parts (Henkel polyamide resin, acid value: 53) Beccasite P-720 3.6 parts (Dainippon Ink and Chemicals, rosin maleic acid resin) Ethoxypropionic acid Ethyl 4.5 parts TSF-4460 0.2 parts Megafac F-177 0.2 parts (Dainippon Ink and Chemicals, a fluorine-based surfactant) Sodium thiocyanate 0.5 parts Solmix AP-7 79.0 parts (Modified alcohol manufactured by Nippon Kasei Co., Ltd.) That is, after sufficiently stirring and dissolving the above-mentioned composition, this solution was filtered using a 0.5 μm membrane filter to obtain an ink composition for a continuous type jet printer. Obtained.

Example 3 An ink composition for a continuous recording type jet printer was prepared according to the following composition ratio. C. I. Solvent Black 29 5.0 parts Joncryl 680 4.5 parts (Styrene acrylic resin manufactured by Johnson Polymer) Bekkasite J-896 4.5 parts (Rosin maleic acid resin manufactured by Dainippon Ink and Chemicals) Propylene glycol monomethyl ether acetate 7. 5 parts TSF-4460 0.2 parts Lithium nitrate 0.5 parts Ethanol 77.8 parts That is, after sufficiently stirring and dissolving the above mixture, the solution is filtered through a 0.5 µ membrane filter to obtain a continuum. An ink composition for a jet printer for a nucleus system was obtained.

Comparative Example 1 An ink composition for a continuous recording type jet printer was prepared according to the following compounding ratio. C. I. Solvent Black 29 6.0 parts Joncryl 68 6.5 parts YP-902 1.5 parts TSF-4460 0.2 parts KF-56 0.1 parts Lithium nitrate 0.5 parts Ethanol 85.2 parts In step 1, Solmix AP-7 was added in place of propylene glycol monomethyl ether acetate, and the mixture was sufficiently stirred and dissolved. The solution was filtered using a 0.5 μm membrane filter to obtain a continuous jet. An ink composition for a printer was obtained.

Comparative Example 2 An ink composition for a continuous recording type jet printer was prepared according to the following compounding ratio. C. I. Basic Violet 3 4.0 parts John Krill 68 6.5 parts YP-902 1.5 parts TSF-4460 0.2 parts KF-56 0.1 parts Lithium nitrate 0.5 parts Ethanol 87.2 parts 1, dye C.I. I. A water-soluble dye soluble in alcohol instead of Solvent Black 29 C.I. I. Basic Violet 3 was added to Solmix AP-7 in place of propylene glycol monomethyl ether acetate, thoroughly stirred and dissolved, and the solution was filtered using a 0.5 μm membrane filter for a continuous system. Was obtained.

Comparative Example 3 An ink composition for a continuous recording type jet printer was prepared according to the following composition ratio. C. I. Solvent Black 29 6.0 parts Joncryl 68 6.5 parts (Styrene acrylic resin manufactured by Johnson Polymer) YP-902 1.5 parts (terpene phenol resin manufactured by Yashara Chemical) Methyl ethyl ketone 6.0 parts TSF-4460 0.2 parts (Toshiba KF-56 0.1 part (silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 part of lithium nitrate 79.2 parts of ethanol In other words, in Example 1, methyl ethyl ketone was used instead of propylene glycol monomethyl ether acetate. Was added, and the mixture was thoroughly stirred and dissolved.
Filtration using a 5 μm membrane filter gave an ink composition for a continuous jet printer.

Test Example 1 Ink compositions for jet printers of Examples 1 to 3 and Comparative Examples 1 to 3 using a continuous inkjet printer "Hitachi IJ Printer HX-P type" manufactured by Hitachi, Ltd. , Environmental temperature 5 ℃ 、 20 ℃ 、 3
Printing was performed on plain paper at 5 ° C. As a result, Examples 1 to 3
In the inks of Comparative Examples 2 and 3, clear print images were obtained under the three conditions of 5 ° C., 20 ° C., and 35 ° C., and the ejection stability was good. On the other hand, the ink of Comparative Example 1
The ejection stability in a 5 ° C. environment was good, but in the 5 ° C. environment, printing disturbance occurred, and the dissolution stability and the ejection stability were insufficient.

Test Example 2 Next, the same printer, Examples 1 to 3 and Comparative Examples 2 and 3
Printing was performed on a glass plate, a metal plate (aluminum, tin-free steel), and a PET film at an environmental temperature of 20 ° C. using the ink composition for a jet printer. As a result, clear printed images were obtained on glass, aluminum, tin-free steel, and PET films.

Test Example 3 Next, the adhesion, abrasion resistance, water resistance, and light resistance of each printed image printed on the above-mentioned printing material were evaluated by the following methods. The results are shown in Tables 1 to 4. (Evaluation method and evaluation criteria) Adhesion test Cellotape (Nichiban Co., Ltd. cellophane adhesive tape)
A peeling test was performed by using the above method, and the presence or absence of peeling of the printed image was visually observed. The evaluation criteria were as follows. ：: No peeling Δ: Partial peeling but legible ×: Peeling and illegible Water Resistance Test-1 Using a rubbing tester, the printed portion was rubbed 50 times with a water-impregnated felt under a load of 0.5 kg / cm ² , and the presence or absence of peeling of the printed image was visually evaluated. The evaluation criteria were as follows. ：: No peeling Δ: Partial peeling but legible ×: Peeling and legible Water resistance test-2 After the printed matter was immersed in tap water for 24 hours, it was rubbed 50 times with the pad of a finger, and the presence or absence of peeling of the printed image was visually evaluated. The evaluation criteria were as follows. ：: No peeling Δ: Partial peeling but legible ×: Peeling and legible Abrasion resistance test The printed portion was rubbed 50 times with the pad of a finger, and the presence or absence of peeling of the printed image was visually evaluated. The evaluation criteria were as follows. ：: No peeling △: Partial peeling but legible ×: Peeling and legible Light fastness test Using a light fastness tester (model name: SUN TEST CPS, Xenon lamp),
Light irradiation was performed for 50 hours, and the printing state thereafter was visually evaluated.
The evaluation criteria were as follows. ○: no change △: thin but readable ×: complete disappearance

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

[Table 4]

As shown in Tables 1 to 4, the ink compositions for jet printers of Examples 1 to 3 and Comparative Example 3 have good adhesion, water resistance, abrasion resistance and light resistance to various recording materials. Had. In contrast, the water resistance and light resistance of the ink composition for a jet printer of Comparative Example 2 were insufficient.

As described above, Examples 1 to 3 and Comparative Example 3
The ink composition for a jet printer is excellent in all of adhesiveness, abrasion resistance, water resistance and light resistance.
That is, the ink composition for a jet printer of Comparative Example 1, which does not contain an ester solvent, has insufficient dissolution stability and ejection stability, and the ink composition for a jet printer of Comparative Example 2, which uses a water-soluble dye, has water resistance. Although the light resistance is not sufficient, the ink compositions for jet printers of Examples 1 to 3 and Comparative Example 3 have excellent adhesion and water resistance to environmental temperatures of 5 to 35 ° C and various recording materials, It has abrasion resistance, light resistance and the like. However, the ink composition for a jet printer of Comparative Example 3 has a ketone solvent content of 1% by weight which is required to be described in the MSDS under the Revised Industrial Safety and Health Law.
And there are safety and health problems. On the other hand, the ink compositions for jet printers of Examples 1 to 3 exhibit excellent physical properties substantially equal to those of the ink composition for jet printers of Comparative Example 3 and also have excellent safety. That is, there is no problem in safety and health, water resistance,
An ink composition for a jet printer having excellent dissolution stability, ejection stability, and the like has been obtained for the first time by the present invention.

[0035]

The ink composition for a jet printer of the present invention has excellent adhesion and water resistance to various recording materials, and has good dissolution stability and discharge stability, especially at low temperatures. It has good dissolution stability and discharge stability, has low toxicity, and has no safety and health problems. In particular, those containing no ketone solvent have higher safety, while those containing 60% by weight or more of ethanol as a lower alcohol component and those containing a chromium complex dye as a water-insoluble dye have water resistance, dissolution stability, and discharge stability. Excellent stability. The ink composition for a jet printer of the present invention is particularly useful for continuous recording.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshiharu Takizawa 1-1-1 Higashitaga-cho, Hitachi City, Ibaraki Prefecture Inside Electric Appliances Division, Hitachi, Ltd. (72) Inventor Hiroaki Takagi 1-1, Higashitaga-machi, Hitachi City, Ibaraki Prefecture -1 F-term in the Hitachi, Ltd.Electrical Equipment Division (Reference) CA07 DA02 EA38 EA41 EA43 EA44 EA45 FA01 FA02 FA04 GA24

Claims (5)

[Claims] An ink composition for a jet printer containing at least a water-insoluble dye, a resin, and a lower alcohol having 4 or less carbon atoms, wherein the ink composition contains an ester solvent.
An ink composition for a jet printer, which is substantially free of a ketone solvent. 2. The ink composition for a jet printer according to claim 1, wherein the ink composition does not contain a ketone-based solvent. 3. The ink composition for a jet printer according to claim 1, wherein the lower alcohol having 4 or less carbon atoms has an ethanol content of 60% by weight or more. 4. The dye according to claim 1, wherein the dye is a chromium complex dye.
The ink composition for a jet printer according to any one of claims 1 to 3. 5. The ink composition for a jet printer according to claim 1, which is for a continuous recording system.