JPH03255179A - Ink - Google Patents

Abstract

PURPOSE:To obtain an ink which is free from clogging at a pen point and a printer head and gives recording excellent in the quality of print by incorporating a specified compound into an ink containing a water-soluble dye, a water-soluble organic solvent, and water. CONSTITUTION:A benzamidine salt (e.g. acetate) is incorporated into an ink containing a water-soluble dye (e.g. C.I. Direct Black 154), a water-soluble organic solvent (e.g. triethylene glycol), and water.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an ink used in various recording instruments such as writing utensils and printers, and more specifically, an ink that has excellent clogging prevention properties and is suitable for use in offices, etc. The present invention relates to an ink that can perform good recording even on plain paper.

(Prior Art) A wide variety of compositions have been reported for inks for writing instruments (fountain pens, signature pens, water-based ballpoint pens, etc.) and inkjet inks.

In particular, in recent years, various aspects such as composition and physical properties have been developed for ink, especially inkjet ink, for good recording even on plain paper commonly used in offices such as copy paper, report paper, notebooks, and stationery. Detailed research and development has been carried out since then.

For example, ink generally contains high-boiling organic solvents such as glycol to prevent drying and clogging, but when recording with such ink on plain paper with a high degree of size, Since the ink does not easily penetrate inside the paper and the drying properties of the recorded area are poor, there were problems with fixation such as the ink getting on your hands when you touch the recorded matter and the letters rubbing and staining.

Therefore, in order to increase the permeability of the ink into the inside of the paper, Japanese Patent Application Laid-Open No. 55-29546 proposes a method of adding a large amount of surfactant to the ink. In this case, depending on the paper, there may be a lot of bleeding, or if the ink is filled into a writing instrument, the ink may drip from the pen tip, or if it is filled into an inkjet head, the head structure may In some cases, the ink retreated from the orifice surface and was not ejected, or conversely, the entire orifice surface became wet and ink was not ejected.

Furthermore, Japanese Patent Application Laid-Open No. 54-104933 and Japanese Patent Publication No. 62
Publication No. 14189 discloses that N,N-bis[polyoxyethylene (or propylene)] -]P-1 is contained in the ink.
- A method of adding luenesulfonic acid amide is disclosed, and although this method is effective in improving the solubility of dyes, it is necessary to add a considerably large amount of polyhydric alcohol to ensure sufficient anti-clogging properties. Because it requires the use of organic solvents such as In order to improve permeability, it is also required to use a surfactant, which results in bleeding and poor printing quality.

Further, when used for inkjet recording and when ink ejection is interrupted, when water etc. evaporates, the above-mentioned compound is in the form of a raft and retreats from the orifice surface, resulting in poor clogging prevention properties.

In addition to the above, various improvements have been attempted up to now, but to date no ink has been known that can solve all of the problems of drying performance, printing quality, and clogging.

(Problem to be Solved by the Invention) Therefore, the purpose of the present invention is to prevent clogging of the printer head even when the pen tip of a writing instrument or printer device is temporarily stopped or stopped for a long period of time, and to prevent clogging in the event that clogging occurs. It is an object of the present invention to provide an ink which is easily recoverable even in the case of ink and which is capable of forming a high-quality image consisting of round dots with little irregular bleeding even on a recording material.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention is an ink containing a water-soluble dye, a water-soluble organic solvent, and water, which is characterized by containing a benzamidine salt.

(Function) As a result of intensive studies on various ink compositions, the present inventors have found that benzamidine is added to the ink in order to prevent nozzle clogging during recording and to obtain high-quality images with less ink bleeding on paper. By including salt, dye solubility improves when the ink is concentrated due to water evaporation, so it is possible to prevent clogging, and in the unlikely event that the volatile components in the ink at the tip of the nozzle of the printer head are completely removed. Even when the benzamidine salt evaporates, the benzamidine salt remains together with the dye, which makes it possible to alleviate the strong agglomeration and precipitation of the dye, making recovery much easier than before.

Furthermore, when ink containing benzamidine salt is ejected as 7a droplets from the nozzle of a printer head, the benzamidine salt rapidly changes due to rapid changes in ink composition due to evaporation and penetration onto the recording material. It was found that due to thickening and crystallization, the printed dots maintain a round shape with little irregular bleeding.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The amount of benzamidine salt added to the ink of the present invention varies depending on the dye used and other liquid medium components used together, but the proportion of benzamidine salt in the ink is 0. The proportion is about 1 to 20% by weight, preferably 1 to 10% by weight. Examples of acids that form salts with benzamidine include inorganic and organic acids such as hydrochloric acid, sulfuric acid, acetic acid, monochloroacetic acid, and citric acid, among which acetate is particularly effective.

Furthermore, the dye used in the present invention has a color index (c
Almost all of the water-soluble acidic dyes 5, direct dyes, basic dyes, and reactive dyes described in Color 1ndex) can be used. Also, any water-soluble dyes listed in 6 that are not listed in the color index can be used.

The amount of these dyes used is not specifically disclosed, but for boat fishing it is approximately 0.1% by weight of the total amount of ink.
A range of 15% is preferred.

Examples of water-soluble organic solvents used in the present invention include amides such as dimethylpolamide and dimethylacetamide; ketones or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene glycol , polyalkylene glycols such as polypropylene glycol; polyalkylene glycols with 2 to 6 carbon atoms such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,26-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, etc. Alkylene glycols containing atoms; glycerin;
Lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether; triethylene glycol dimethyl (or ethyl) ether, tetraethylene glycol Lower dialkyl ethers of polyhydric alcohols such as dimethyl (or ethyl) ether; sulfolane, N-methyl-2-pyrrolidone, l
, 3-dimethyl-2-imidazolidinone, and the like.

The content of the water-soluble organic solvent is 1 to 40% by weight, preferably 3 to 30% by weight.

In particular, the amount of wetting agents such as polyhydric alcohols that are commonly used for the purpose of preventing clogging is 1. Due to the anti-clogging effect of the benzamidine salt used in the present invention, there is no need to use a large amount; When containing 40% by weight or more,
This results in poor print drying properties and print quality on paper.

In addition to the above ingredients, the ink of the present invention may optionally contain a water-soluble organic solvent, a surfactant, a pH adjuster, a rust preventive agent, a preservative, a fungicide, an antioxidant, an evaporation accelerator, and a chelating agent. agent,
Various additives such as water-soluble polymers may be added.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples. In the text, parts and percentages are based on weight unless otherwise specified.

X-affected soil 21 Combine the following ingredients and stir thoroughly to dissolve, then filter with a fluorobore filter (Sumitomo Electric Ni!I) with a pore size of 0.45 μm.
J) to obtain four types of inks of the present invention.

m=l ink C, 1, Direct Black 154 4 parts benzamidine acetate 7 parts triethylene glycol 10 parts water
79 parts-2 ink.

C, 1, Food Black 2 3 parts Benzamidine hydrochloride (n hydrate) 5 parts diethylene glycol 10 parts isopropyl alcohol 4 parts water
78 parts 3 ink and C, 1, Direct Blue 86 3.5 parts benzamidine hydrochloride (n-hydrate) 10 parts glycerin
10th part score roll #900
(Surfactant) 0.1 part water
76.4 parts - 4III3 ink bud C, 1, acid red 35 3 parts benzamidine acetate 4 parts polyethylene glycol 300 10 parts diethylene glycol monophenyl ether 3 parts water 8
0 parts Comparative Examples 1 to 4 Comparative Example Inks 1 to 4 were prepared by treating the components in the same manner as in Example 1 except for removing the benzamidine salt contained in the inks of Examples 1 to 4 and replacing the content with water. Obtained.

Comparative Example 5 The salt of benzamidine in the ink component of Example 2 was
Comparative Example Ink 5 was obtained by processing in the same manner as in Example 4 except that gC82CONHz·HCI was used.

Next, using the obtained inks of Examples 1 to 4 and Comparative Examples 1 to 5, an inkjet printer BJ-130 (trade name: manufactured by Canon ■) using a heating element as an ink ejection energy source was used as an inkjet recording device. ) was used to evaluate clogging properties and print quality. The results are shown in Table 1 below.

[Evaluation method and evaluation criteria] (1) Clogging resistance evaluation After filling the printer with the specified ink and printing alphanumeric characters continuously for 10 minutes, stop printing, cap it, and leave it for 30 days (leave it unattended). Conditions: 40℃ and 10±5%
RH), a recovery operation for the nozzle clogging was performed, alphanumeric characters were printed again, and judgment was made based on the number of recovery operations and the presence or absence of defects such as faded or missing characters.

○...Printing equivalent to initial printing is possible after 0 to 3 recovery operations.

△...Printing equivalent to the initial one is possible after 4 to 9 recovery operations.

×...Printing equivalent to the initial one is possible after performing recovery operations 10 times or more.

(2) Print quality evaluation After printing on commercially available copy paper (XEROX 4024), leave it for more than 1 hour, and then see if there is any bleeding at the dot level.
Edge sharpness was evaluated under environmental conditions of 25° C. and 60% RH.

○: There is no bleeding and the edges are sharp.

△: Some bleeding is observed, and the edges are also slightly blurred.

×: There is a lot of bleeding, and dots and edges are blurred.

(Effects) As explained above, the ink of the present invention enables highly reliable recording that does not cause clogging at the pen tip or the tip of a fine orifice for a long period of time, and is further adapted for inkjet use. Not only paper but also copy paper, report paper,
Even on plain paper commonly used in offices such as notebooks and stationery, records with no bleeding and excellent print quality can be obtained.

Claims (1)

[Claims] (1) An ink containing a water-soluble dye, a water-soluble organic solvent, and water, characterized by containing a benzamidine salt.