JPH116075A - Ink jet head and production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high reliability ink jet head by sticking a water-repellent film having high water repellency and not causing peeling. SOLUTION: A nickel coating film contg. uniformly dispersed fine fluororesin particles is stuck by electroless plating to the outer circumferential face of an orifice plate around an ink jetting hole. The electroless plating is carried out while keeping a plating blocking member in close contact with the inner circumferential face of the orifice plate so as to plate only the outer circumferential face of the orifice plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head used in an ink jet recording apparatus, and ejects a recording liquid, generally called ink, as fine droplets from fine discharge ports, and flies the droplets onto a recording surface. The present invention relates to an ink jet head for performing recording by adhesion, and more particularly to an ink jet head for improving the surface treatment of ink ejection ports and a manufacturing method.

[0002]

2. Description of the Related Art FIG. 4 shows an ink jet head generally used conventionally. In the drawing, FIG.
(B)-(e) are exploded perspective views of the inkjet head shown in FIG. (A). In these figures, reference numeral 1 denotes a base made of, for example, a plastic member, and a pressure chamber 2 made of, for example, a cone or a quadrangular pyramid (a hole inclined from the short side of the rectangle toward the back surface in the figure) is formed on the base 1. Has been
At the bottom of the pressure chamber 2, a fine hole 2a is formed.
Reference numeral 3 denotes an orifice plate, and the orifice plate 3 is also formed with a fine hole 3a at a position located at the aforementioned fine hole 2a.

[0003] Reference numeral 4 denotes a flow path plate which is air-tightly fixed on the base 1. The flow path plate 4 has a hole 4 a having a shape similar to the shape above the pressure chamber 2 at a position located in the pressure chamber 2. Have been. Reference numeral 5 denotes a diaphragm made of, for example, stainless steel, which is formed airtight on the flow path plate 4. A piezoelectric element 6 is mounted on the diaphragm 5 and at a position located above the pressure chamber 2. Reference numeral 7 denotes a cylindrical ink tank. An ink inlet 7a is formed above the tank, and an ink outlet 7b is formed below the tank.

A hole 4b formed at a position corresponding to the hole 7b below the ink tank 7 is formed in the flow path plate 4 and the diaphragm 5.
And 6a are formed. 4c is a flow path formed in the flow path plate 4, connecting the holes 4a and 4b. The outer periphery of the ink tank 7 is air-tightly fixed to the diaphragm 5.

In the above arrangement, when the ink is introduced from the ink inlet 7a, the ink reaches the pressure chamber 2 through the flow path 4c, but the surface tension of the ink and the water repellent member applied near the micro holes 3a are applied. Due to the effect (not shown), the ink does not ooze out of the fine holes 3a under atmospheric pressure. When a pulse voltage is applied to the upper surface of the piezoelectric element 6 and the stainless steel diaphragm 5 in a state where the ink is filled in the pressure chamber 2, an electric field is generated on both surfaces of the piezoelectric element 6, and the piezoelectric element 6 contracts in the plane direction. At this time, the piezoelectric element 6
Deflects the diaphragm 5, so that the volume of the pressure chamber 2 changes to generate pressure in the ink, and the ink is ejected from the micro holes 3a.

[0006]

The operation of discharging ink in the ink jet head having such a configuration is as shown in FIG. That is, when the piezoelectric element 1 bends in FIG. 5A, the ink 11 is pushed out as shown in FIG. 5B and flies as ink droplets as shown in FIG.

In such a conventional ink jet head, when the surface energy near the discharge port is high (that is, when the metal plate is used as the orifice plate) (that is, when the ink is easily wetted by the ink), the ink is discharged from the discharge port. As described later, there is often a problem that the ink adheres to the vicinity and makes the ink ejection unstable.

FIG. 6 shows a state in which the ink adheres substantially uniformly around the ink discharge port. In such a case, the surface tension of the ink acts greatly, and the ink is normally (in the vicinity of the discharge port). The amount of ink discharged is smaller than that of the discharge (with no ink attached) or the ink is not discharged.

Further, when the ink adheres to only one side as shown in FIGS. 7A to 7D, there is a problem that accurate printing cannot be performed since the ink flies obliquely, and there is a serious problem. Means that the ink near the ejection port dries and adheres,
It may cause ink clogging.

In order to solve such a problem, a film of a fluorine compound is coated around the discharge port (Japanese Patent Publication No. Hei 3-43065), or the vicinity of the discharge port is ionized, so that the ink is wetted with ions of opposite polarity. Including an inhibitor (Japanese Patent Publication No. 3-33110), the shape of the discharge port is devised so that ink does not adhere thereto (Japanese Patent Publication No. Sho 63-2).
No. 1620).

However, in the method described above, since the adhesion between the fluorine compound and the orifice plate is weak, the fluorine compound is partially peeled off due to friction with the ink due to ejection of the ink or cleaning of the vicinity of the ejection port during maintenance. In addition, there is a problem that the water-repellent effect is lost due to this, and there is a problem that the discharge port is blocked because a process such as coating is mainly performed when forming a film.

Further, the method described in (1) has a problem that a special chemical must be contained in the ink, and the method described in (1) has difficulty in processing the orifice. There was a problem. 8A and 8B show a case where plating is formed on both surfaces of the orifice plate 3. FIG. 8A shows a state in which no voltage is applied. FIG. 8B shows a state in which ink flies by applying a voltage.
Is a state in which the inside of the orifice plate 3 also has water repellency after the ink is ejected, so that the ink mechanics near the ejection port retreats inward, and the diameter of the portion in contact with the fine holes 2a and 3a of the bubbles is larger than the diameter of the fine holes. (D) shows a state in which bubbles remain on the inner surface. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and a highly reliable ink jet head having a high water repellent effect and a non-peeling water repellent film is attached to the outer peripheral surface of an orifice plate. The purpose is to provide.

[0013]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an electroless plating of a nickel film in which fine particles of a fluororesin are uniformly dispersed on an outer peripheral surface of an orifice plate around a discharge port for discharging ink. The plating process is performed with the plating prevention member in close contact with the inner peripheral surface of the orifice plate so that plating is performed only on the outer peripheral surface of the orifice plate. It is characterized by having made it.

[0014]

FIG. 1 shows an ink jet head according to an embodiment of the present invention, which has the same shape as that of the conventional example shown in FIG. In the present invention, the electroless plating 10 is applied only to the outer peripheral surface (one surface of the orifice plate) of the orifice plate 3 of the conventional example. For this electroless plating treatment, Kaniflon (trade name, manufactured by Nihon Kanigen Co., Ltd.) was used. The components and properties of the resulting film are as follows. Nickel (Ni) 83 to 86 wt% Phosphorus (p) 7.5 to 9 wt% Fluororesin 6 to 8.5 wt% (20 to 25 vol%) Fluororesin particle size <1 μm Density 6.4 to 6.8 g / cm ³ Hardness 250-350Hv after plating 400-500Hv after heat treatment

FIGS. 2A and 2B show a plating jig for performing electroless plating on an orifice plate.
The figure shows four screw holes 12 formed at the four corners of the jig pedestal 12.
The orifice plate 3 is disposed at the center of the position a, and both ends thereof are pressed by a long plate-like pressing plate 13 and fixed by screws 14.
(B) The figure shows the assembled state. The plating is performed by dipping in the above-described electrolytic plating solution. By doing so, only the outside of the orifice plate is plated.

FIGS. 3A and 3B show an ink discharging operation according to the present invention in which plating is applied to only one side of the orifice plate 3. FIG. (A) As shown in the figure, the ink recedes after the ink is ejected, but there is no water repellency inside the orifice plate.
a) It does not spread more. Therefore, there is no water repellency on the inside as shown in FIG. 2B, so that bubbles do not adhere to the inner surface of the orifice plate.

As a method of plating only on one side (or a necessary portion), there is a method of applying a masking tape to a portion where it is not desired to deposit, or a method of applying a masking agent such as a polymer material. There is a possibility that the orifice plate may be deformed when peeling off, and the masking agent may fall off in the pretreatment step of plating (washing with an acid or an alkaline organic solvent) in the method described in (1).

Although FIGS. 1 and 3 show plating on portions other than the ink discharge ports, plating may be performed only near the discharge ports. Further, the electroless plating is not limited to the above-described embodiment, and can be changed as needed, as long as a film in which a fluororesin is uniformly dispersed can be obtained.

[0019]

As described above, according to the present invention,
A nickel coating in which fine particles of fluororesin were uniformly dispersed was applied to the outer peripheral surface of the orifice plate around the discharge port for discharging ink by an electroless plating method, and a plating prevention member was adhered to the inner peripheral surface of the orifice plate. The plating process was performed in the state. Therefore, the outer peripheral surface of the nozzle can have a water-repellent effect. As a result, the ink ejection direction is stabilized, and the ejection amount is also stabilized. Since ink does not adhere to the vicinity of the discharge port, clogging is less likely to occur. At the time of ink ejection, the force (surface tension) for pulling the ink toward the head decreases, so that smaller ink droplets can be ejected and ejection at a lower driving voltage is possible.

Also, since electroless plating is used,
The thickness of the plating is easy to control, and the surface layer can be plated without closing the fine holes. The plating process is easy (low cost). Since the adhesion of the plating film is good and it is hard to peel off, the water repellent effect lasts a long time. And so on.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of an ink jet head showing an example of an embodiment of the present invention.

FIG. 2 is a perspective view showing an example of a method of attaching an orifice plate during plating.

FIG. 3 is a diagram showing an ink ejection operation when plating is applied to both surfaces of an orifice plate.

FIG. 4 is a diagram illustrating an ink discharging operation when plating is performed only on one surface of an orifice plate.

FIG. 5 is a sectional view of a main part of a conventional inkjet head.

FIG. 6 is a cross-sectional view of a main part showing an ink discharging operation of the ink jet head.

FIG. 7 is a cross-sectional view of a main part showing an ink discharging operation when ink adheres to the entire periphery of the discharge port of the orifice plate.

FIG. 8 is a cross-sectional view of a main part showing an ink discharging operation when ink adheres to a part of a discharge port of an orifice plate.

[Explanation of symbols]

 Reference Signs List 1 base 2 pressure chamber 3 orifice plate 4 flow path plate 4c, 10a flow path 5 diaphragm 6 piezoelectric element 7 ink tank 7a ink inlet 10 plating

Claims (2)

[Claims] 1. An ink jet head comprising a nickel film in which fine particles of a fluororesin are uniformly dispersed adhered to an outer peripheral surface of an orifice plate around a discharge port for discharging ink by an electroless plating method. 2. An ink jet printing method, wherein plating is performed in a state where a plating prevention member is in close contact with an inner peripheral surface of an orifice plate, whereby plating is performed only on an outer peripheral surface of the orifice plate. Head manufacturing method.