JP2572619B2 - Oil-based black ink - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an oil-based black ink which has excellent stability over time and good ink ejection.

(Conventional technology and its problems) Conventional oil-based black inks include nigrosine as a colorant, fatty acids such as oleic acid as a solubilizer, and xylene and toluene as solvents because of their high concentration and low cost. Although those using aromatic hydrocarbons and the like have been known, they have problems such as odor and toxicity, and oil-based inks using alcohol solvents as solvents have been used.

However, the oil-based ink has many problems in that the ink is poorly printed, and the ink is blurred over time, making writing impossible.

(Means for Solving the Problems) In view of the above problems, the present inventors have conducted intensive studies,
Finally, the present invention has been completed, that is, its gist is as follows:
Oil-based black ink containing at least nigrosine, an aliphatic alcohol, dodecylbenzenesulfonic acid and a substance represented by the following general formula I (However, n is 1 or 2)

 Hereinafter, the present invention will be described in detail.

Nigrosine is used as a coloring agent, and its addition amount is preferably 7 to 15% by weight based on the total amount of the ink. The concentration decreases as the addition amount decreases, and the viscosity increases as the addition amount increases. There is a tendency.

Aliphatic alcohol is used as a solvent,
Specifically, one or a mixture of two or more of methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, etc. is used, and the amount of addition is 40 to 90% by weight is preferred. Furthermore, an aliphatic alcohol having 3 or less carbon atoms is more preferable from the viewpoint of handwriting drying.

Dodecylbenzenesulfonic acid is used as a solubilizing agent, and the amount added is 1 to the total amount of the ink.
The content is preferably 5% by weight, and if it is less than 1% by weight, the effect tends to be small, and if it is more than 5% by weight, the viscosity tends to be high.

The substance represented by the following general formula I is used as an ink output improver, and its addition amount is preferably from 0.1 to 1.0%, and if it is less than 0.1% by weight, the effect is reduced, and more than 1.0% by weight. , The viscosity tends to increase.

(However, n is 1 or 2) In addition to the above components, various additives such as rosin resin, phenol resin, ketone resin, and other alcohol-soluble resins, rust inhibitors, and various activators are appropriately selected. It can be used.

(Action) It is not clear why the oil-based black ink of the present invention has excellent stability over time and good ink output, but it is presumed as follows.

Nigrosine shows excellent solubility in dodecylbenzenesulfonic acid, and furthermore, has excellent compatibility with aliphatic alcohols, so that it is considered that nigrosine is stably dissolved.

In addition, when the substance represented by the following general formula I exerts some action on the ink, the wettability to the writing surface is improved, and the ink ejection is improved.

(However, n is 1 or 2) (Example) Hereinafter, an example will be described in more detail. In the examples and comparative examples, “parts” simply indicates “parts by weight”.

Example 1 Each of the above components was stirred with a commercially available stirrer for 4 hours to obtain an oily black ink.

Comparative Example 1 An oil-based black ink was obtained in the same manner as in Example 1 except that dodecylbenzenesulfonic acid was removed from Example 1 and oleic acid was added in the same amount.

Example 2 Oil-based black ink was obtained in the same manner as in Example 1 using each of the above components.

Comparative Example 2 From Example 2 And oily black ink was obtained in the same manner as in Example 2 except that ethanol was increased by that amount.

Example 3 Oil-based black ink was obtained in the same manner as in Example 1 using each of the above components.

Comparative Example 3 Dodecylbenzenesulfonic acid was removed from Example 3, and capric acid was added in that amount. , Except that the amount of n-propanol was increased by the same amount as in Example 3, to obtain an oily black ink.

Example 4 Example 1 Was increased to 2.0 parts by weight and ethanol was reduced by that amount to obtain an oily black ink in the same manner as in Example 1.

Comparative Example 4 From Example 4 Except that amount Was added in the same manner as in Example 4 except that an oily black ink was obtained.

(Effects) The oil-based black inks obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were obtained from a commercially available Mark Pentel Fine (Pentel Co., Ltd.).
The results of an ink ejection test and a stability test over time are shown in Table 1.

As described above, according to the present invention, an oil-based black ink having excellent stability over time and excellent ink ejection properties can be obtained.

Also, the oil-based black ink of the present invention is not only for writing implements,
It can be used enough for recorders and jet printers.

Claims (1)

(57) [Claims] 1. An oil-based black ink containing at least nigrosine, an aliphatic alcohol, dodecylbenzenesulfonic acid and a substance represented by the following general formula I. (However, n is 1 or 2)