JPS60204372A - Surface-cleaning method for nozzle - Google Patents

Abstract

PURPOSE:To enhance reliability of nozzles, a head or the like through an excellent cleaning effect and clean the surfaces of nozzles speedily, efficiently and inexpensively, by subjecting the nozzles for ejecting liquid droplets to a plasma treatment. CONSTITUTION:The nozzles for ejecting liquid droplets are subjected to a plasma treatment by, e.g., a plasma treating device, to clean the nozzles. To preferably perform the treatment, for example, a multiplicity of nozzles 1 are set in a plasma-generating chamber 3 through holding jigs 2, a vacuum pump 4 is operated to draw a vacuum in the chamber 3, an inorganic gas is introduced into the chamber 3 through a gas inflow port 5, and an RF oscillator 6 connected to electrodes 7 is operated to impress an HF current on the electodes 7, thereby bringing the gas in the chamber 3 into a plasma state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for cleaning the surface of a nozzle, and particularly to a method for cleaning the surface of a nozzle that discharges droplets and is used in a liquid jet recording head or the like.

[Prior Art] In the manufacturing process of the nozzle used in the above-mentioned so-called inkjet head to eject recording liquid ink as droplets, the nozzle is first formed from a material such as glass or ceramics, and the method is as follows. something is known.

(a) A method in which a nozzle wall is formed by cutting fine grooves in a plate made of glass or ceramics, and then another flat plate made of the above-mentioned material is bonded to this plate to form a nozzle.

(b) A method in which a nozzle wall is formed using photosensitive glass or photosensitive resin, and then another flat plate material is joined to form a nozzle in the same manner as in (a).

(C) A method in which a part of the glass tube is softened by heating and a tapered part is formed at both ends by pulling both ends of the heating part, and then cut at a desired part to form a nozzle.

After the nozzle is formed by the various methods described above, the surface of the nozzle is purified.

The reason for cleaning here is to remove foreign matter such as dirt that originally adhered to the nozzle forming material and dust that adhered to the nozzle during nozzle formation to ensure an ink flow path, and to clean the inside of the nozzle. This is to improve the smoldering property of the nozzle against the ink, prevent the adhesion of air bubbles, and stabilize the ink ejection characteristics.

Conventionally, this cleaning method has been carried out by cleaning the nozzle. Specifically, for example, the nozzle is immersed in a cleaning liquid such as a surfactant or an organic solvent, shaken, and then rinsed with water to remove the above-mentioned cleaning liquid. A common method is to wash away the water, then heat the nozzle to dry the water. This cleaning completes the nozzle.

However, according to this cleaning method,
Since the inner diameter of the nozzle for an inkjet head is extremely small, ranging from several pLm to several hundred p.m, the following problems occur.

(a) The cleaning effect is not sufficient because it is difficult for the cleaning liquid to enter the nozzle.

(b) Similarly, when rinsing with water after cleaning with a cleaning liquid, it is difficult for water to enter the nozzle, so the cleaning liquid remains in the nozzle without being completely washed away, impairing the wettability of the inner surface of the nozzle.

(c) In order to overcome the problems in (a) and (b) above and perform sufficient purification, a long cleaning time is required, resulting in poor nozzle production efficiency.

The following problems are not limited to nozzles of inkjet heads, but are common to surface cleaning methods for nozzles that eject similar types of droplets.

[Purpose] The present invention has been made in view of the problems of the conventional methods as described below.It is an object of the present invention to provide a method for purifying the surface of a nozzle, which can be purified efficiently and inexpensively in a short time, and which has an excellent purifying effect. The purpose is

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. In the embodiment, the nozzle for the above-mentioned inkjet head is targeted.

In the present invention, the nozzle surface is cleaned by subjecting the nozzle to plasma treatment.

As a specific plasma processing method, a commercially available plasma processing apparatus shown in FIG. 1 is used.

First, as shown in the figure, a large number of nozzles 1 are installed in a chamber 3 for plasma generation of the device via a holding jig 2, and then a vacuum pump 4 connected to the chamber 3 is installed.
is activated to generate air and make the inside of the chamber 3 into a vacuum state.

Next, an inorganic gas that forms plasma is allowed to flow into the chamber 3 from the gas inlet 5 . This inflow is such that the gas pressure in chamber 3 is at the desired low pressure, preferably 0.1
Continue until it becomes ~ several mm 1 (.

In this case, the gases include oxygen, nitrogen, helium,
Although argon or a mixed gas of these gases can be used, it is preferable to use oxygen in view of the strength of the purifying action, price, etc.

After that, the R F (Radio Frequency) connected to the electrode 7.7 provided in the chamber 3 is
) Activate the transmitter 6 to apply a high frequency current to the electrodes 7, 7 to bring the gas in the chamber 3 into a plasma state. In this case, the output of the RF oscillator 6 is preferably about 50 to 500W.

As the nozzle 1 is exposed to the plasma generated in the chamber 3 as described above, minute dust and dirt adhere to the surface of the nozzle 1.

Foreign matter and the like are decomposed and removed by chemical phenomena such as oxidation, and the surface of the nozzle l is purified. In addition, due to the high temperature generated in the chamber 3 due to the generation of plasma, the above oxidation 1
Decomposition is promoted, and the purification effect of the plasma described above is further enhanced.

Note that the time required for this plasma treatment is about 5 minutes to 20 minutes.

According to the above-described method of this embodiment, the plasma treatment time is 5 to 20 minutes as described above, and a large number of nozzles 1 can be treated at the same time, making it possible to perform extremely efficient purification. .

Incidentally, the surfaces of sample nozzles were actually cleaned using the above method and the conventional cleaning method, and a nozzle inner surface wettability test was conducted on the cleaned nozzles.

The specific processing conditions, Wl resistance test results, and data on the time required for purification are shown in the table below.
, which was formed into a cylindrical shape with a total length of 25 III m was used.

As shown in this table, in the conventional method, samples of 50 nozzles were subjected to ultrasonic washing for 25 minutes at room temperature using a detergent, and then ultrasonic washing was further performed for 25 minutes under running water. That is, the time required for purification was 50 minutes, excluding the subsequent drying. In this case, the detergent is MERCK as a surfactant.
Extran MA・Ol made by Reisu was used.

In addition, in the method according to the example, the plasma processing apparatus described above is used to treat samples of 50 trees each with the 5
It was subjected to regular plasma treatment. That is, under the common conditions that the gas used was oxygen and the pressure was 1 mm 1 g, five treatments were performed with the output of the RF oscillator 6 and the processing time set to different silks as shown in the table.

Connect the rear end of the purified nozzle l to the ink container 8.
The nozzle 1 was immersed in the liquid level of the ink 9 filled therein, and the nozzle 1 was stood upright on the ink liquid level, and the time required for the ink to rise from the rear end of the nozzle 1 to the tip by capillary action was measured.

When such a wettability test was conducted on 50 samples each whose surface was purified by the conventional method and the method of this embodiment, the results were obtained in the range shown in the table above.

As is clear from the table, according to the method of this example, the time required for purification was 10 minutes in Examples 1 to 3, 9 5 minutes in Example 4, 9 20 minutes in Example 5.
This is an extremely short time compared to 50 minutes of the conventional method. In addition, in all of Examples 1 to 5, the ink rise time in the wettability test was significantly shorter than that of the conventional method, confirming that the method of this example has a purification effect superior to that of the conventional method. It was done.

Note that the method of the present invention is of course applicable not only to the nozzles of inkjet heads, but also to surface cleaning of nozzles that eject similar droplets.

[Effects] As is clear from the above explanation, according to the nozzle surface purification method of the present invention, the nozzle is purified by plasma treatment, so that the nozzle can be purified efficiently in an extremely short time. This makes it possible to reduce the cost of the nozzle, and improve the reliability of the nozzle due to its excellent purification effect. In the case of nozzles for inkjet heads, the reliability of the head can be improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of plasma treatment in the nozzle surface purification method according to the present invention, and FIG. 2 is an explanatory diagram showing a wettability test by the capillary rise method. 1... Nozzle 2... Jig 3... Chamber 4... Vacuum pump 6... RF
Oscillator 7... Electrode 8... Ink container 9... Ink 0 19th () 2 Sense 2 Tomi

Claims (1)

[Claims] A method for purifying the surface of a nozzle that discharges liquid droplets, the method comprising performing the aforementioned purification by subjecting the nozzle to plasma treatment.