JPS60170675A - Oil-based ink for ink jet printer - Google Patents

Abstract

PURPOSE:To provide the titled ink composed of a specific dye, an aliphatic hydrocarbon, and a liquid fatty acid inert to a resin, storable stably for a long period, usable without causing the clogging of the recording nozzle nor the generation of bubbles, having quick drying property and low viscosity, and useful for the recording head made of polysulfone resin, etc. CONSTITUTION:The titled ink having a viscosity of <=10CP is produced by compounding (A) an oil-soluble dye, (B) preferably 5-30wt% liquid fatty acid (e.g. oleic acid) inert to an amorphous thermoplastic resin and (C) preferably 60-70% 8-13C aliphatic hydrocarbon (e.g. n-dodecane).

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to inks for use in drop-on-demand inkjet printers.

For the recording head of this system, the applicant has realized the manufacture of a resin head by using an amorphous thermoplastic resin among polymer resins, and by assembling a different base material, and has already filed an application. There is.

Among these, the present invention relates to an oil-based ink for a recording head using polysulfone resin, polyethersulfone resin, or ABS resin as a base material.

[Prior art]

Currently, water-based inks used in heads whose base material is amorphous thermoplastic resin tend to generate bubbles in the ink due to the high vapor pressure of water, which is the main component of the composition. Because the contact angle of the aqueous ink to the surface of the amorphous thermoplastic resin is large, the air bubbles generated or mixed into the ink flow path during ink filling cannot be removed even if the air bubbles are removed. There was a problem in that recording was impossible because the ink could not be pressurized in the pressurizing chamber.

Furthermore, water-based inks have drawbacks such as long printing drying times and poor water resistance.Therefore, several inkjet oil-based inks made of organic solvents with low vapor pressure have been reported.

However, in general, amorphous thermoplastic resins have low chemical resistance to many organic solvents, and resins that incorporate internal stress due to various reasons such as melted resin may suffer from cracks and cracks due to contact with organic solvents. and become unusable. For this reason, conventional oil-based inks cannot be used in heads made of amorphous thermoplastic resin.

〔the purpose〕

The object of the present invention is to solve such problems, namely:
Inert to amorphous thermoplastic resins and stable in contact with liquids.
Moreover, the ink does not clog the nozzles of the recording head, which is essential for inkjet ink, the ink does not deteriorate over a long period of time and is stable, and the ink density is high when transferred to paper. It satisfies conditions such as dot diameter dust and clear contrast, and also suppresses the generation of air bubbles in the ink flow path of the head, which cannot be solved with water-based ink. It is an object of the present invention to provide a removable, low viscosity inkjet oil-based ink of 100 PS or less.

[Structure] The composition of the inkjet oil-based ink of the present invention will be described below.

First, an organic solvent with low vapor pressure and low viscosity is required that does not dissolve the polysulfone resin and will not cause cracks in the resin, which incorporates internal stress, making it unusable.

The humectant lowers the overall vapor pressure of the ink, slows the evaporation of other solvent components in the ink, and prevents nozzle clogging by dissolving the dye. Therefore, oil-soluble,
Liquid fatty acids and polyethylene glycol ethers are preferred because they have high dye solubility, are inert to polysulfone resin, and have low vapor pressure.Specifically, oleic acid, linoleic acid, and polyethylene are preferred. Examples include glycol monooleyl ether.

Regarding the amount of wetting agent added, if it is too small, clogging in the nozzle is likely to occur, and if it is too large, the viscosity of the ink as a whole increases, which is not preferable. - Therefore, it is preferable to add from 5 to % by weight of wetting agents; it is also possible to use a mixture of these wetting agents.

The organic solvent used as the main solvent satisfies conditions such as having a considerably lower vapor pressure than water, high solubility of oil-soluble dyes and the above-mentioned wetting agent, and being inert to polysulfone resin. Group hydrocarbons are desirable. Specifically, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, and n-tetradecane are preferable, and these may be used alone or in combination. is also available.

The addition amount is 60 to 70 SK based on the total amount of ink, thereby realizing a low viscosity ink.

Regarding the above wetting agents and aliphatic hydrocarbons, the polysulfone resin does not dissolve under high temperature conditions of 70°C.
Furthermore, the resin did not crack and become unusable for polysulfone resins having a residual stress of 8o Q/cm'' or less, and was stable for a long period of time.

Furthermore, when these organic solvents were dissolved in polyether sulfone resin and ABS resin, they remained multistable for a long period of time without causing cracks and rendering them unusable.

As for the dye, it is desirable to have a dye that has high solubility in the organic solvent mentioned above and can remain stably in the quinque for a long period of time, such as Negro V 7 Hose B X
, HR-';l L, AP-fl, A
P-8, AY-8, 185L, 808L, TBLC
Orient chemical film]. It is better to add a large amount of dye in order to obtain sufficient contrast, but if the amount exceeds toii or s, nozzle clogging is likely to occur, so it is desirable to add less than 100 g of dye.

In the ink manufacturing method of the present invention, a liquid fatty acid or the like as a wetting agent is charged at a constant rate into a container equipped with a stirrer and a reflux device, and an oil-soluble dye is gradually added while stirring. The container is gradually heated, and when the dye is sufficiently dissolved, the main solvent, such as an aliphatic hydrocarbon, is added, and stirring is continued for 6 hours while keeping the temperature inside the container constant at (100° C.). After cooling to room temperature, the mixture is allowed to stand for about an hour and then filtered through a 1 μm millibore Teflon filter to obtain the desired ink.

Examples will be explained below.

Example 1 (Composition) The ink obtained based on the above composition was of course fzl
nte, viscosity 4.3CP, surface tension 80.1 dye
/cm. At 70C high temperature, so? /c
When polysulfone resin, polyethersulfone resin, and ABS resin, which have residual stress at the m'' level, were brought into contact with this ink, the solubility of the resin and the occurrence of cracks were investigated, and it was found that the ink was stable over a long period of time. Furthermore, when we filled our prototype multi-nozzle polysulfone head with this ink and printed, we were able to obtain clear black and high-quality print records.
It was. The drying time of the ink on the recording paper after printing was within 5 seconds, indicating good quick-drying properties.

Further, the ink having the above composition was placed in a container made of porcelain glass, and the container was sealed tightly and allowed to stand at a high temperature of 700℃ for 8 months, but no insoluble matter was observed in the ink.

Furthermore, its low vapor pressure makes it possible to suppress the generation of air bubbles in the flow path when subjected to extremely busy and high temperatures compared to conventional water-based inks. It has become possible to eliminate them with a simple removal operation.

Example 2 (Composition) The ink prepared with the above composition had a viscosity of B,
6 cp, surface tension 29.8 dyψ, Example 1
It had almost the same characteristics.

Example 8 (Composition) The ink prepared with the above composition has a viscosity of 4.
8CP, surface silver crab dO, 9dyu/α, and Example 1 and l tusk have similar characteristics and bfc.

Example 4 (Composition) The obtained ink had a viscosity of 3.7 cp at elevated temperature.
The surface tension was 81.4 dyψ.

〔effect〕

As described above, the inks shown in Examples 1 to 4 were filled into a multi-nozzle polysulfone head manufactured by our company as a prototype, and after additional jet printing was performed, the nozzles were left open to the atmosphere for about 100 hours. When the ink of this Example was ejected again, good ejection printing was performed without any clogging. The ink also has good storage stability at high temperatures; after being left in an environment of 70°C for 8 months, the ink remained stable.
No generation of insoluble matter was observed.

Furthermore, the ink of this Example was inert to polysulfone resin, polyethersulfone resin, and ABS resin, and was stable without dissolving the resin or causing cracks.

This has made it possible to use oil-based inks in heads made of polysulfone resin, polyethersulfone, resin, and ABS resin in the same way as water-based inks.

In addition, the use of oil-based ink can improve the problems that occur with water-based ink, such as the tendency for air bubbles to form in the ink and the difficulty in removing air bubbles that exist in the flow path, and greatly improve reliability as an inkjet ink. did.

In addition, the drying time after printing is within 5 seconds.
Epson Corporation

Claims (1)

[Claims] Oil-soluble dyes, liquid fatty acids that are inert to amorphous thermoplastic resins, and aliphatic hydrocarbons (8 to 13 carbon atoms)
) An oil-based ink for inkjet printers, characterized in that it has a uniform composition and a viscosity of 11) CP or less.