JPH06234943A - Jet recording ink - Google Patents

Abstract

PURPOSE:To obtain a jet recording ink made proof against the bacterial growth and nozzle plugging and improved in safety by adding an antibacterial agent containing 1,2-benzisothiazolin-3-one to a water-based ink. CONSTITUTION:0.05-1.0wt.% antibacterial agent containing 1,2-benzisothiazolin-3- one is added to a water-based ink used in an ink jet recording system and comprising 5-50wt.% liquid medium comprising water and a water-soluble organic solvent and 0.5-10wt.% water-soluble dye when the water content of the ink component is above 50wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording ink for recording by ejecting droplets from a nozzle orifice of a recording head.

[0002]

2. Description of the Related Art Ink jet recording methods include a method of mechanically vibrating or displacing ink (recording liquid) by using a piezoelectric element, a method of heating ink to foam instantaneously and utilizing its pressure. This is a recording method in which ink droplets are generated by the method and adhered to a recording medium such as paper to perform recording, and is attracting attention as a recording method that can generate high-speed recording with less noise.

Ink jet recording inks are roughly classified into
It is classified into solvent-based ink and water-based ink. Solvent-based inks have good dryness to paper and excellent moisture retention, so ink does not easily clog in nozzle orifices, but the surface tension is low compared to water-based inks, so ink easily bleeds on paper. However, there is a problem that the print quality is deteriorated. Alternatively, there is a problem that the ink causes a liquid contact material, that is, a member such as a tube or a nozzle of a recording apparatus, which is in direct contact with the ink, and the melted material clogs a nozzle orifice or a filter. Has become. The components of the water-based ink are composed of water as a main solvent, polyhydric alcohol as a wetting agent, and dye as a colorant.

The recording liquid used in the ink jet recording apparatus has physical properties such as viscosity and surface tension which can match the flying speed, the flying direction of the recording liquid, the ejection stability and the like to the recording head. Required. Further, the recording liquid is required not to cause non-ejection of ink during storage for a long period of time and during suspension of recording or during continuous recording. Alternatively, it is required that the recorded image has high contrast, is clear, and has high printing density.

Further, since the water-based ink used in the ink jet recording apparatus uses 50% or more of water as a main solvent, if the ink is left for a long time, a clogging phenomenon occurs due to various factors. As one of the problems, there is a problem that microorganisms such as molds, spoilage fungi, and algae adhere to the ink and propagate, resulting in clogging of nozzles and the like. Alternatively, there is a case where mold propagates due to the ink adhering to the platen rubber of the recording apparatus. As a countermeasure against this problem of microorganisms, there is known a recording ink such as JP-A-1-213376 in which a basic substance is contained so that the ink pH is in the range of 12 to 14 so that microorganisms and the like are not propagated. However, there was a problem in safety because it was strongly alkaline.

[0006]

The ink is required not to be clogged, but some phenomena called "clogging" are conceivable, such as a phenomenon caused by thickening of the ink due to evaporation of water at the nozzle tip. , Crystallization of dye,
The phenomenon in which the nozzle tip is blocked and ejection failure occurs due to the formation of insoluble inorganic salts, the generation of insoluble solid matter due to the generation of molds, spoilage fungi, microorganisms such as algae, and the like.

Problems such as thickening of ink and precipitation of dye caused by evaporation of water can be solved by selecting a wetting agent having low viscosity and high dye solubility, but insoluble caused by generation of mold in aqueous ink. It is difficult to solve the nozzle clogging due to the solid matter because it is not described in the literature or the like. From JP-A-1-213376, there is already known a recording ink characterized in that the recording liquid contains a basic substance and the ink pH is in the range of 12 to 14.
Since the above-mentioned ink has a high pH value due to the basic substance, propagation of bacteria and the like does not easily occur without adding a bacteriostatic agent. However, when the above-mentioned ink is used, if the user touches the ink directly or with the ink recorded on the surface of the recording paper, irritation peculiar to the stimulus occurs on the skin. Had.

[0008]

In order to solve the above-mentioned problems, the present invention provides a water-based ink used in an ink jet recording system in which droplets are ejected from a nozzle orifice of a recording head to perform recording. Content rate is 5
When it exceeds 0%, 1.2 benzisothiazoline-3-
The above-mentioned 1.
The present invention provides an inkjet recording ink characterized in that the addition amount of the antibacterial agent containing 2 benzisothiazolin-3-one is in the range of 0.05 to 1.0% by weight. The effect of the antibacterial agent is exerted at a content of 0.05% by weight, and a sufficient effect is observed within 1.0% by weight, and it is not necessary to add any more.

The recording liquid of the present invention is a main liquid medium component of water, and for example, it is desirable to use a mixture of water and various water-soluble organic solvents. Examples of the water-soluble organic solvent include methyl alcohol, ethyl alcohol, n
-Propyl alcohol, isopropyl alcohol, n-
Butyl alcohol, sec-butyl alcohol, ter
C1-C4 alkyl alcohols such as t-butyl alcohol and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones such as acetone and diacetone alcohols; or keto alcohols; ethylene glycol, propylene glycol, butylene Alkylene glycols having an alkylene group of 2 to 6 carbon atoms such as glycol, triethylene glycol, hexylene glycol and diethylene glycol; polyhydric alcohols such as glycerin, ethylene glycol methyl ether, diethylene glycol methyl ether and trierylene glycol monomethyl ether. Examples include lower alkyl ethers.

The content of the above water-soluble organic solvent in the recording liquid is generally 5 to 5 in weight percent with respect to the total weight of the recording liquid.
It is set within the range of 50%. The water-soluble dye preferably used in the present invention is selected from direct dyes, acid dyes, reactive dyes and the like.

Specifically, as a direct dye, C.I. I. D
direct Yellow 12, 26, 86, 13
0, C.I. I. Direct Magenta 9,1
3, 17, 227, C.I. I. Direct Blue
78, 86, 90, 199, C.I. I. Direct B
rack 19, 22, 154, 168 etc. are raised. As the reactive dye, C.I. I. Reactive R
ed 180 etc. are raised.

The content of the above-mentioned water-soluble dye is determined depending on the type of liquid medium, the physical properties required for the recording liquid, etc., but is generally 0.1% by weight based on the total weight of the recording liquid. The range is 5 to 10%, preferably 0.5 to 6%, more preferably 1 to 5%.

[0013]

EXAMPLES In the present invention, as a bactericidal agent, an aqueous propylene glycol solution containing 10% of 1.2 benzisothiazolin-3-one (trade name: PROXEL XL-2, ICI)
A confirmation experiment was performed on the inks A to E and the conventional ink F.

(Example 1) Ink A Direct Black 154 3 parts by weight Triethylene glycol 38 parts by weight Diethylene glycol monobutyl ether 1 part by weight Proxel XL-2 0.2 parts by weight Pure water 57.8 parts by weight (Example 2) Ink B Direct Black 154 3 parts by weight Triethylene glycol 20 parts by weight Proxel XL-2 0.3 parts by weight Pure water 76.8 parts by weight (Example 3) Ink C Direct Yellow 86 3 parts by weight Triethylene glycol 38 parts by weight Diethylene glycol mono Butyl ether 1 part by weight Proxel XL-2 0.2 parts by weight Pure water 57.8 parts by weight (Example 4) Ink D Direct Yellow 86 3 parts by weight Diethylene glycol 25 parts by weight Proxel XL-2 0.25 parts by weight Water 71.8 parts by weight (Example 5) Ink E Direct Red 9 3 parts by weight Proxel XL-2 0.4 parts by weight Pure water 96.8 parts by weight (Comparative Conventional Example) Ink F Direct Black 154 3 parts by weight Tri Ethylene glycol 38 parts by weight Diethylene glycol monobutyl ether 1 part by weight Pure water 58 parts by weight A clogging substitute test was conducted on the above ink. The results are shown in Table 1. Each evaluation test of the recording ink was carried out by the following method.

[Clogging Substitute Test] Test ink was poured into a watch glass, and the test ink was injected under the environment of 20 ° C. and 60% RH for 1, 3,
Leave it for 6 to 12 months and check if there is any foreign matter. ◯: No foreign matter was found. X: Foreign matter was found.

[0016]

[Table 1] From the above results, it can be said that since the A to E inks do not show the formation of insoluble solid matters such as foreign matters, it is possible to prevent nozzle clogging. On the other hand, in the conventional example F ink, a defect accompanied by the generation of a foreign substance was observed from about 6 months after leaving it due to the growth of microorganisms that are considered to be blue-green, and the foreign substance that could be visually confirmed was generated, and the nozzle diameter was 80 μm. It can be said that clogging occurs at a certain width. From the results shown in Table 1, the antibacterial effect of the ink of the present invention is clear.

Table 2 shows the results of the ink antibacterial test of the inks A to E of Examples 1 to 5. The test method was according to the following method. [Test contents] 0.1 ml of the bacterial solution was added to 20 g of each ink so that the theoretical number of bacteria added after inoculating the bacterial solution was about 10 ⁵ per 1 g, and the mixture was sufficiently mixed and stored at 25 ° C. did. Next, the number of each viable cell after 7, 14, 21 and 28 days of storage was measured by a pour plate culture method using a cell count medium. The culture was carried out at 35 ° C. for 2 days for bacteria, and at 25 ° C. for 7 days for yeast and mold.

[0018]

[Table 2] From Table 2, when the number of bacteria added to the inks A to D is mixed bacteria or Candida, the number of bacteria becomes less than 100 after 7 days of storage. In Koji mold, the number of bacteria becomes less than 100 after 14 days of storage. From the above results, it can be said that reproduction of microorganisms such as molds, spoilage fungi, and algae does not occur in the ink containing the antibacterial agent.

Further, an Ames test was conducted in order to confirm whether or not the above ink had any safety problem. A
The mes test (mutagenicity test) is a property (mutation) in which a chemical substance acts on an organism's gene (DNA, deoxyribonucleic acid) to selectively cause a chemical reaction or change part of its molecular structure. It is a test to check whether or not it is

The strains used for the Ames test, among the Salmonella, histidine auxotrophy that can not be synthesized histidine ^(his--) in strains of a result of the test substance is applied to the strain, such that histidine regain synthesis The number of colonies of the histidine non-auxotrophic (his ⁺ ) revertant that has become a substance is counted to determine whether the substance is mutagenic. Currently, among these strains, TA153
5, the use of TA1537, TA100, TA98 is generally recommended.

Strains used in the mutagenicity test for the ink jet recording ink of the present invention include TA98 and TA100.
Ames test is carried out in combination with the direct test in which the substance to be tested acts on the bacterial cells as it is and the metabolic activation test in which the drug metabolism activating enzyme in microorganisms (so-called S-9Mix) is incorporated and tested. did.

[0022]

[Table 3] The determination was negative because no clear number of reversion colonies was observed in the entire volume range of the test substance relative to the negative control value and no volume dependence was observed. It goes without saying that as the antibacterial agent used in the present invention, good results can be obtained even in an aqueous solution containing 1.2 benzisothiazolin-3-one other than the antibacterial agents mentioned in the examples.

[0023]

INDUSTRIAL APPLICABILITY In a water diameter ink in which the water content in the ink component exceeds 50%, 1.2 benzoisothiazoline-
Addition of antibacterial agent containing 3-one prevents the growth of microorganisms such as molds, spoilage fungi, and algae that occur in the ink, and prevents the nozzle tip from clogging due to the formation of insoluble solid matter. It becomes possible to do. Further, since the pH of the ink is neutral, even if the ink accidentally adheres to the skin of the hand, face, etc., it does not cause inflammation and is very excellent in safety.

Claims (2)

[Claims] 1. A water-based ink used in an ink jet recording system in which droplets are ejected from a nozzle orifice of a recording head for recording, and 1.2 benzisothiazoline is used when the water content in the ink component exceeds 50%. -3
An ink for ink jet recording, which is characterized by adding an antibacterial agent containing one. 2. The 1.2 benzisothiazoline-3-
Addition amount of antibacterial agent including on is 0.05 by weight percent
The ink for inkjet recording according to claim 1, which is in the range of from 1.0% to 1.0%.