JPH08230195A - Manufacture of ink jet head - Google Patents

Abstract

PURPOSE: To manufacture an ink jet head at low cost, which jets ink with a high precision. CONSTITUTION: A plurality of nozzle holes 6 are provided in the direction of a thickness of a passage substrate 3. The passage substrate is molded into two colors in such a manner that an inlet side 31 is made of a plastic material which can not be plated and a jetting side 32 is made of a plastic material which can be plated. The passage substrate 3 is treated with degreasing, etching, catalizer, accelerator, and treated with electroless plating and a plating layer 9 is formed only on a jetting section 6b. At this time, the inner face of the nozzle hole at an inlet section 6a is activated by the series of treatments and hydrophilic property is heightened, so that induction of an ink at the time of ink drop jetting is accelerated. It is cleaned after completion of plating and a water-repellent material layer 10 is formed on the surface of the plating layer 9 by fluoro-electrodeposition coating. Thus, the water-repellent property of the nozzle hole at the jetting side 32 is heightened, so that the ink can be easily dissociated at the time of ink drop jetting and straight-ahead property of ink drops is heightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an ink jet head.

[0002]

2. Description of the Related Art There are various types of ink jet heads including on-demand type ink jet heads.
Ink droplets are ejected toward a recording medium from nozzle holes provided in a nozzle plate or a flow path substrate.

By the way, in order to improve the print quality,
It is desired that the ink droplets ejected from the nozzle holes have the same size and have a straight-ahead traveling property (trajectory), and that there are few so-called satellites composed of small droplets scattered around the ink droplets. For this purpose, firstly, the shape and diameter of the nozzle hole are formed uniformly and with high accuracy, and secondly, as a condition that the ink droplet is smoothly separated from the ink in the nozzle hole, It is required that the inner surface has high water repellency.

As an example of the structure of the nozzle portion of an ink jet head, there is one in which a nozzle hole is provided in a nozzle plate on the opening end side of an ink channel provided in a channel substrate so as to face the opening portion. (JP-A-4-358
841).

The ink droplets ejected from the nozzle holes are often accompanied by a decrease in straightness due to adhesion to the nozzle portion, which is one of the causes of deterioration in print quality. The inner surface of the nozzle hole is made highly water repellent. For example, the flow path substrate is a plastic molded product, and a stainless steel plate having nozzle holes is used as the nozzle plate. The nozzle holes are subjected to dispersion plating of ceramic or the like to improve water repellency.

[0006]

In the above-mentioned conventional ink jet head, since stainless steel is used as the nozzle plate, there is a problem that cost is increased because joining and processing are troublesome. Further, by forming a plating layer having water repellency in the nozzle hole,
The generation of satellites can be prevented. However, in this case, since the diameter of the nozzle hole is as small as a few microns, it becomes difficult for ink to enter the inside from the nozzle inlet side (decrease in priming property), and there is a problem that ink droplet ejection is impeded. In particular, it causes inconvenience when replacing the ink cartridge.

Further, when the nozzle plate is made of stainless steel, there is a problem that the manufacturing cost becomes high because the machining of the nozzle hole is troublesome. For example, when nozzle holes are formed in a stainless steel plate by laser processing or the like, there arises a problem that it is difficult to obtain high print quality because it is difficult to perform uniform and accurate drilling.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent the deterioration of the straight running performance of ink droplets and to improve the priming property, thereby making it possible to manufacture an ink jet head capable of high quality printing at low cost. .

[0009]

In order to achieve the above object, the present invention is a method for manufacturing an ink jet head formed by two-color molding of a flow path substrate having a plurality of nozzle holes penetrating in the plate thickness direction. The two-color molding is performed by a combination of a plastic material that can be plated on the injection port side of the nozzle hole and a non-platable plastic material on the inlet side, and the inner surface of the nozzle hole is subjected to hydrophilic treatment. It is characterized by including a step of forming a water-repellent substance layer only on the inner surface of the nozzle hole on the injection port side later.

Preferably, as a pre-process for forming the water repellent material layer, electroless plating is applied only to the inner surface of the nozzle hole on the injection port side to form a plating layer, and the water repellent material is formed on the plating layer. A layer is formed.

More preferably, in the step of forming the water-repellent substance, a substance in which a fluororesin is mixed with a substance which can be electrodeposited is used.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, an outline of the configuration of an inkjet head manufactured according to the present invention will be described. Figure 2
As shown in FIG. 3, the inkjet head assembly is formed by laminating and assembling plastic molded products including the ink pool substrate 1, the intermediate plate 2, and the flow path substrate 3. The ink pool substrate 1 has a concave portion 1a for the ink pool formed on the front surface of the disk, and the ink supply portion 1 on the center portion of the back surface.
b is projected. The middle plate 2 is composed of a circular plate having the same plane shape as the ink pool substrate 1, and the ink pool 4 is defined between the two by being superposed on the front surface of the ink pool substrate. The intermediate plate 2 is provided with a restrictor 5 for ink supply at a position facing an outer end portion of an ink flow path described later.
Has been drilled. The flow path substrate 3 is an entrance side 3 having a large disc shape.
1 and a small disc-shaped injection port side 32 are integrally molded. At the center of the ejection port side 32, ejection port portions 6b of the plurality of nozzle holes 6 are arranged. The material of the flow path substrate 3 is
The inlet side 31 is a non-platable plastic material such as PSF (polysulfone) material, and the outlet side 32 is ABS.
It is made of a plateable plastic material such as (acrylonitrile butadiene styrene), and both are integrally molded by two-color molding.

As shown in FIG. 4, a predetermined number of ink channel grooves 3a are radially formed on the rear surface of the channel substrate 3, and the ink channel grooves 3a are formed at positions near the outer ends of the respective ink channel grooves. The pressure chamber 3b is formed in each case. The inner ends of the ink flow channel grooves 3a are dead ends in the vicinity of the central portion, and at these dead ends, the nozzle holes 6 which have already been described toward the front are provided.
Is provided.

A vibrating plate 7 and a piezoelectric element 8 are mounted on the front surface (upper surface in FIG. 3) of the flow path substrate 3 facing the ink flow path. The piezoelectric element 8 can apply vibrational energy to the ink in the pressure chamber by applying a signal output from a circuit board (not shown) to eject the ink from the nozzle hole 6. Actually, the same number of vibrating plates 7 and piezoelectric elements 8 as the ink flow path grooves 3a are provided, but they are omitted in FIGS.

As shown in FIG. 1, each nozzle 6 has a straight tubular shape at the entrance 6a located at the entrance side 31 and a tapered hole at the injection opening 6b located at the injection opening 32 side. A plating layer 9 is formed on the injection port portion 6b by electroless plating with nickel or the like, and a water-repellent substance layer 10 is further formed thereon, and the entrance portion 6a is used as a pretreatment for the electroless plating treatment. The hydrophilicity is increased by the etching treatment. Therefore, the ink sent out into the ink flow path 3b is easily introduced into the nozzle hole 6 at the inlet portion 6a, and when ejecting the ink droplet, the ink droplet is easily ejected from the ink inside the nozzle at the ejection outlet portion 6b. Since it is separated into two, the deterioration of the straight running performance due to ink adhesion is prevented, and high quality printing is possible.

Next, a method of manufacturing the above ink jet head will be described. In this embodiment, since the ink pool substrate 1 and the intermediate plate 2 are injection-molded products such as PSF resin as in the prior art, the manufacturing method of the flow path substrate 3 will be mainly described here.

As described above, the flow path substrate 3 is formed by two-color molding in which the inlet side 31 is made of non-platable plastic material PSF resin and the injection side 32 is made of plateable plastic material ABS resin. Mold into a predetermined shape. In this molding, the nozzle hole 6 has an inlet portion 6a formed in a straight tube shape and an injection opening portion 6b formed in a tapered shape.

Next, a pretreatment for performing the electrodeposition coating treatment is performed. The following processing is performed as an example of the preprocessing. First,
The flow path substrate 3 is degreased by immersing it in an aqueous solution of sodium hydroxide (NaOH) with a surfactant added. Then, this is immersed in an aqueous solution of sulfuric acid (H ₂ SO ₄ ) and chromic anhydride (CrO ₃ ) to perform etching treatment. By this etching, the butadiene component in the ABS, which is the injection port side 32, is dissolved and a concave mark is formed on the surface. Next, a catalyst application (catalyzer) treatment of tin (Sn) and palladium (Pd) is performed. As a result, molecules of Sn and Pd are attached to the surface of the ABS material and the dents, and a state in which plating is easily performed is created. Subsequently, an accelerator (activation) treatment is performed with hydrochloric acid (HCl) or sulfuric acid (H ₂ SO ₄ ). Finally, electroless plating is performed to form a Ni-P alloy plating layer on the surface of the ABS material.

As described above, when the flow path substrate 3 made of the ABS material and the PSF material is treated in the plating process for the ABS resin, the inlet side 31 is exposed by the chromic acid-sulfuric acid bath which is an etching solution. The hydrophilicity of the constituent PSF resin is improved. However, unlike the butadiene component of ABS, the etching action does not work specifically. The electroless plating layer will not be deposited and formed on the PSF material even if the subsequent catalyst application (catalyzer) made of Sn-Pd colloid and the activation treatment (for example, dilute hydrochloric acid) of the catalyst are performed. . In this way, the electroless plating layer is made of ABS material on the injection port side 3
The plating layer 9 is formed by selectively depositing only on 2.

The plating layer 9 may be electroless nickel or electroless copper plating, and may be composed of a plurality of plating layers of the same kind or different compositions if necessary. By the way, when the plating layer is formed to a thickness of about 3 to 10 μm by electroless plating, the thickness of the deposited film is within ± 1 μm and a film with high dimensional accuracy is formed.

Further, after the plating treatment, after sufficient washing with water, anion type fluorine resin coating treatment is continuously performed in the wet state. Since the film formed by this is non-conductive, when a voltage is applied to the film, the electric resistance increases as the film is formed, and after a certain processing time, a uniform fluorine film is formed. A water repellent material layer 10 made of is formed. As the film thickness,
When it is applied to about 10 μm, a film having a highly accurate film thickness within ± 1 μm is obtained, and excellent water repellency is imparted. In this way,
In electrodeposition coating, accurate finishing accuracy can be obtained by adjusting the voltage and the processing time. Therefore, by adjusting the thickness of the water repellent material layer 10, a nozzle hole having a desired size can be obtained.

In the prior art, after the electrodeposition coating, in order to improve the priming property, as a hydrophilicity-imparting treatment, it is general to treat with chromic acid-sulfuric acid or sulfuric acid or an organic solvent such as dimethylformamide (DMF). there were. However, in this example, the PSF resin was already subjected to the chromic acid-sulfuric acid treatment at the same time when the ABS resin was subjected to the etching treatment, and the hydrophilicity was sufficiently improved. It is possible to omit. Assuming that this is not enough hydrophilicity,
Even when the treatment liquid is treated again as described above, the fluororesin coating has sufficient resistance to these treatment liquids, so that the injection port side 32 does not have hydrophilicity, and only the inlet portion 31 made of the PSF material is used. Can be imparted with hydrophilicity.

Thereafter, the flow path substrate 3 is dried, the intermediate plate 2 and the intermediate plate 2 are joined together by a film adhesive (not shown), and the peripheral parts such as the piezoelectric element described above are mounted to form an ink jet. Head assembly.

The nozzle hole 6 of the ink jet head obtained by the above-described steps has two contradictory properties, that is, the inlet portion 6a has high hydrophilicity and the ejection outlet portion 6b has high water repellency. Therefore, the ink supplied from the ink flow path to the nozzle hole is easily introduced into the nozzle hole from the inlet portion 6a. When the ink is ejected from the nozzle hole 6 by applying energy from the piezoelectric element to the pressure chamber, the ink in the nozzle hole and the ink droplet can be easily separated at the ejection port 6b. ,
Ink drop straightness is high.

In the above-mentioned embodiment, the inner surface of the nozzle hole is metal-plated and then electro-deposition coating is applied. However, the surface of the ABS is activated by the catalyzer and accelerator treatments to enable electro-deposition coating. Since it is in a state, the plating process is omitted, and the AB process is performed directly after the etching, catalyzer, and accelerator processes.
It is also possible to perform an electrodeposition coating process on S. Alternatively, it is possible to directly form a water-repellent plating layer on the ABS surface after the accelerator treatment and omit the electrodeposition coating.

In this embodiment, the two-color molding in the flow path substrate 3 is described as a combination of PSF resin and ABS resin, but in addition to this, the following combination of resins may be used. . For example, as the non-platable plastic material, either PS (polycarbonate) or PES (polyether sulfone) may be used in addition to PSF. In addition to ABS, POM (polyoxymethylene) and PB are also available as platable plastic materials.
Either T (polybutylene terephthalate) or PA (polyamide) may be used. Similar effects can be obtained by appropriately combining plastic materials having these contradictory properties.

[0027]

According to the present invention, since it is possible to provide the nozzle hole with two different properties, that is, hydrophilicity and water repellency, it is easy to introduce the ink into the nozzle hole and the ejected ink. The straight-ahead performance of the drops can be improved. Further, since the flow path substrate having the nozzle holes having the above properties can be obtained by the two-color molding of plastic, it contributes to the reduction of the manufacturing cost. Further, since the hydrophilic property is simultaneously imparted to the inlet side portion by etching treatment on the ejection port side of the nozzle hole, a hydrophilic substance can be obtained without particularly treating the inlet side to impart hydrophilicity. There is an effect that can be. Also, when the water repellent material layer is formed by electrodeposition coating, it is possible to finish with high dimensional accuracy, so that the nozzle hole diameter is accurate and an inkjet head with high printing quality is manufactured at a low manufacturing cost. It will be possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a state in which a plating layer is formed in a nozzle hole and a water-repellent substance layer is further formed thereon.

FIG. 2 is a cross-sectional view of a main part of an inkjet head.

FIG. 3 is a perspective view of an inkjet head.

FIG. 4 is a rear view of the flow path substrate.

[Explanation of symbols]

 3 Flow path substrate 31 Entrance side 32 Injection port side 6 Nozzle hole 9 Plating layer 10 Water repellent substance layer (Electrodeposition coating layer)

Claims (3)

[Claims] 1. A method of manufacturing an ink jet head, comprising forming a flow path substrate having a plurality of nozzle holes penetrating in a plate thickness direction by two-color molding, wherein the two-color molding is performed on the injection port side of the nozzle hole. Is used as a plastic material that can be plated, and the inlet side is made of a non-platable plastic material. After the hydrophilic treatment is applied to the inner surface of the nozzle hole, only the inner surface of the nozzle hole on the injection port side is processed. A method for manufacturing an inkjet head, comprising a step of forming a water repellent material layer. 2. The plating process according to claim 1, wherein as a pre-process for forming the water-repellent substance layer, electroless plating is applied only to the inner surface of the nozzle hole on the injection port side to form a plating layer. A method for manufacturing an inkjet head, comprising forming the water-repellent substance layer on a layer. 3. The inkjet head manufacturing method according to claim 1 or 2, wherein the water repellent material forming step is electrodeposition coating of a mixture of fluororesin into a material capable of electrodeposition coating. Method.