JPS61181879A - Oil based ink composition for ink jet recording - Google Patents

Abstract

PURPOSE:To provide a compsn. which can dispense with an inorg. salt of a resistivity modifier and causes neither corrosion nor or clogging, by using a solvent mixture of a high-resistivity solvent and a low-resistivity solvent in the title compsn. contg. an org. solvent-soluble dye dissolved in an org. solvent. CONSTITUTION:A low-resistivity solvent (A) selected from among dialkyl esters of aliph. dicarboxylic acids, benzyl ester of aliph. carboxylic acids, trialkyl phosphates, dialkylene glycol alkyl ethers, benzyl alcohol, polyxyalkylene glycols and alkoxynaphthalenes is mixed with a high resistivity solvent (B) selected from among high-boiling arom. hydrocarbon solvents (e.g. naphthalene and diphenylmethane) to prepare a solvent mixture having a resistivity within a proper range. An org. solvent-soluble dye (e.g. Neosabon Blue) is dissolved in said solvent mixture to obtain the desired oil based ink compsn. for ink jet recording.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an oil-based ink applied to an inkjet recording system. More specifically, the present invention relates to an oil-based ink composition for inkjet recording that is used in a recording device that enables stable recording and high-definition images by jetting ink from an ink jetting port using pressure or electrostatic attraction.

(Prior Art) Ink droplet generation methods in inkjet recording devices include electrostatic acceleration type, pressurized vibration type, pressurized jet type, and pressure pulse type, but all of these methods use fine ink jet orifices. have. In order to perform stable recording from these fine ink ejection ports, the ink is required to have several appropriate physical property values. One of the important physical property values is the resistivity value, and it is necessary to keep this value within an appropriate range.

Conventionally, it was common to add a resistivity value adjuster to adjust the resistivity value to a normal range, and this adjuster includes chlorides such as lithium chloride and ammonium chloride, and nitrates such as lithium nitrate and ammonium nitrate. Inorganic salts such as acetates such as ammonium acetate, potassium acetate, etc. were used. However, these conditioners have drawbacks, such as corroding metal parts such as electrodes that come into contact with the ink, or forming deposits in the ink, which can cause nozzle clogging.

(Problems to be Solved by the Invention) The present invention does not use the resistivity regulator as described above, but instead uses a specific resistance regulator by adjusting the resistivity to an appropriate range using a combination of specific solvents. This prevents corrosion of metal parts such as electrodes and clogging of nozzles caused by deposits.

(Means for solving the problem) Oil-based ink is made by dissolving and dispersing an oil-soluble dye in a solvent. The properties of the solvent used in the ink require a high boiling point and low vapor pressure in order to prevent changes in ink physical properties and generation of precipitates due to solvent evaporation during ink storage and during recording stops. There are various solvents with high boiling points and low vapor pressures, and their specific resistance values range from 10'oh
It has a wide range up to ``oh-・1.Also, even if the solvent used is the same, it varies depending on the type and amount of dye dissolved.
The specific resistance value of the ink changes. However, the inventors
By using an appropriate combination of a solvent with a high resistivity value and a solvent with a low resistivity value depending on the type and amount of dye to be dissolved, it is possible to adjust the resistivity value of the ink to an appropriate range. This discovery led to the present invention.

In the present invention, as an ink solvent, +11 aliphatic dicarboxylic acid dialkyl ester, aliphatic carboxylic acid benzyl ester, phosphoric acid trialkyl ester, dialkylene glycol alkyl ether,
At least one solvent selected from the group consisting of benzyl alcohol, polyoxyalkylene glycol, and alkoxynaphthalene (low resistivity solvent), and (2) a high boiling point aromatic hydrocarbon solvent (high resistivity solvent).
It is characterized by using a mixed solvent consisting of.

Specific examples of low resistivity solvents include aliphatic dicarboxylic acid dialkyl esters such as sebacic acid dibutyl ester, succinic acid diethyl ester, geltaric acid dimethyl ester, succinic acid dimethyl ester, and dimethyl adipate;
Fatty acid benzyl esters such as benzyl acetate; trialkyl phosphoric acid esters such as triethyl phosphate, tributyl phosphate, trioctyl phosphate; diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether ,
Examples include dialkylene glycol alkyl ethers such as diethylene glycol dibutyl ether, diethylene glycol monohexyl ether, and diethylene glycol diethyl ether; benzyl alcohol; polyoxyalkylene glycols such as polyethylene glycol and polypropylene glycol; and alkoxynaphthalenes such as methoxynaphthalene and ethoxynaphthalene. These solvents have a resistivity of 10' to 10'' ohs-cm.

Preferred specific examples of high resistivity solvents include naphthalene and its alkyl substituted products such as naphthalene, dimethylnaphthalene, trimethylnaphthalene, and diisopropylnaphthalene; diphenylalkanes and their alkyl substituted products such as diphenylmethane, phenethylcumene, and phenylxylylethane; Examples include boiling point petroleum-based aromatic hydrocarbon solvents. As such a solvent, rKMC11 manufactured by Kureha Chemical Industry Co., Ltd.
3J, Exxon Chemical Co., Ltd. rEC3200J, rEcs
100IJ, “Tsurupets 150”; rKMC210 manufactured by Kureha Chemical Co., Ltd. and “Megata Hysol” manufactured by Japan Petrochemical Co., Ltd.
Products such as SAS 296J can be used. These solvents have a resistivity of 10" to 10" ohm.

When a dye is dissolved in a solvent, the specific resistance value of the solution generally decreases. If the dye is dissolved in the low resistivity solvent at a normal concentration, it is not possible to use only the low resistivity solvent. However, by using a general dye that is commonly used as a color component of oil-based ink for inkjet printers, the content in the ink is adjusted to an appropriate concentration (1
~10%), high resistivity solvent 45 ~
By selecting the mixing ratio of true solvent in the range of 85% and low resistivity solvent in the range of 15 to 55%, the resistivity value of the ink can be adjusted to the appropriate range (10' to 10') required for the printer model.
oh■·cII) can be freely adjusted to any value.

In the present invention, there are no particular limitations on color components, and various organic solvent-soluble dyes can be used. Specific examples include "Neozapon Blue 806" and "Neozapon Blue 807".
” (manufactured by BASF), “Oil Blue 615J (manufactured by Orient Chemical Industry Co., Ltd.), “Orazol Blue GNJ”
(manufactured by Ciba Geigy), [Oleosole Fast Blue GLJ (manufactured by Taoka Chemical Co., Ltd.), "Oil Yellow 101", "Oil Yellow 107J (manufactured by Orient Chemical Co., Ltd.), "Neozapon Yellow 073J
(manufactured by BASF), "Macrolex Yellow"
6GJ (manufactured by BAYER), "Oil Black"
HBBJ, “Varifast Black 3806J,” “Nicrosin Base EXJ, [Spirit Black A]
BJ (manufactured by Orient Chemical Co., Ltd.), [Oleosole Fast Blank RLJ (manufactured by Taoka Chemical Co., Ltd.), [Sudan Black X60J (manufactured by BASF), [Kayascent Black K-RJ (manufactured by Nippon Kayaku Co., Ltd.)]
"Oil Pink 312" (manufactured by Orient Chemical Co., Ltd.),
"Eisen Spilon Left C-BHJ (manufactured by Hodogaya Chemical Industry Co., Ltd.) is an example.

The ink according to the present invention can be prepared by adding a dye to the mixed solvent of the low resistivity solvent and high resistivity solvent, stirring it under heat to dissolve and disperse it, and filtering after cooling to remove impurities. . Auxiliary agents such as an anti-drying agent and a surface tension adjusting agent may be added to the ink as necessary.

The present invention will be explained in more detail with reference to the following examples, where 0 parts represent parts by weight.

Example 1 rEC5200J 29 parts rEC
S 100IJ 29 parts rKMC
210J 24 parts Diethylene glycol monoethyl ether 14 parts [Oil Black HBBJ Part A The above components were dissolved and dispersed by stirring under heating, and after cooling, they were filtered to remove impurities. The specific resistance value of the obtained ink was 5.6X 10
The ink was able to be adjusted within the appropriate range.It does not cause corrosion of the electrodes or other metal parts that come into contact with the printer's ink, and does not generate precipitates that can cause nozzle clogging. It had a good shelf life.

Examples 2 to 19 Inks having various compositions listed in Table 1 were prepared in the same manner as in Example 1. Each ink had a specific resistance value within an appropriate range as shown in the same table, and each ink did not cause corrosion of recording electrodes, etc., did not generate precipitates, and had good storage stability.

Table 1 Table 1 Table 1 Table 1 In Table 1, rDBEJ and rDBE-9J are both ``ADEKA CARPOL M-2'' and ``ADEKA CARPOL MBF-■'' manufactured by DuPont Japan. All OOJs are polyoxyalkylene glycols.

(Effects of the Invention) In the present invention, as a means for adjusting the specific resistance value of the ink within an appropriate range, a mixed solvent of a specific high specific resistance solvent and a low specific resistance solvent is used as a solvent, and the conventional ink Do not add inorganic salts, which were added as resistivity adjusters. Therefore, the disadvantages of conventional inks caused by the addition of inorganic salts, such as corrosion of the metal parts of the printer that come into contact with the ink, such as recording electrodes, and the formation of precipitates that cause nozzle clogging can be prevented. be done.

Claims (1)

[Claims] 1. In an oil-based ink composition for inkjet recording comprising an organic solvent-soluble dye dissolved in an organic solvent, as the organic solvent, (1) an aliphatic dicarboxylic acid dialkyl ester, an aliphatic carboxylic acid benzyl ester, a trialkyl phosphate; A mixed solvent consisting of at least one solvent selected from the group consisting of ester, dialkylene glycol alkyl ether, benzyl alcohol, polyoxyalkylene glycol, and alkoxynaphthalene, and (2) a high-boiling aromatic hydrocarbon solvent is used. An oil-based ink composition for inkjet recording.