JP2007001242A - Inkjet recording head and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an inkjet recording head which performs stable discharge for a long time even if a highly alkaline ink is used, or a fine orifice is prepared. <P>SOLUTION: The method of manufacturing the inkjet recording head includes steps of: forming an ink flow passage pattern on a substrate where ink discharge pressure generating elements are formed with a soluble resin layer; forming a coated resin layer being an ink passage wall in the soluble resin layer; forming ink discharge ports above the ink discharge pressure generating elements by photolithography; and forming an ink flow passage by solving out the soluble resin layer. The method is characterized in that the coated resin layer as the wall of the ink flow passage has an organic filler. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording head for generating recording liquid droplets used in an ink jet recording system and a method for manufacturing the same.

  An ink jet recording head applied to an ink jet recording method (liquid jet recording method) is generally a fine ink discharge port (hereinafter referred to as “orifice”), a liquid flow path, and a liquid discharge provided in a part of the liquid flow path. It has multiple energy generators. Conventionally, as a method for producing such an ink jet recording head, for example, the following steps described in Patent Document 1 are known.

  First, an ink flow path pattern is formed of a resin that can be dissolved on a substrate on which an ink discharge pressure generating element is formed, and an epoxy resin and a photocationic polymerization initiator that serve as an ink flow wall are formed on the ink flow path pattern. A covering resin layer is formed, an orifice is formed on the ink discharge pressure generating element by photolithography, and then the soluble resin is eluted to cure the covering resin layer serving as the ink flow path wall.

  Examples of the epoxy resin contained in the coating resin serving as the ink flow path wall include an epoxy resin having a bisphenol A, F, S skeleton and an O-cresol novolac type epoxy resin described in Patent Document 2. Moreover, the epoxy resin etc. which have the oxycyclohexane frame | skeleton of patent documents 3-6 are known.

  By the way, with the progress of recent recording technology, higher-definition recording is required for the inkjet recording technology. One method that satisfies this requirement is minimization of ink droplets ejected by the ink jet recording head, that is, miniaturization of the ink jet recording head.

  However, when an ink jet recording head having an extremely small orifice is manufactured by a conventional manufacturing method, the influence of volume swelling due to ink absorption on the ink flow path wall cannot be ignored, and there is a possibility that the orifice is deformed (orifice area is reduced, etc.). . As a result, when the ejection direction of the ejected ink droplets varies or the ejected ink droplets are small, there is a possibility that the output image will be uneven.

  In addition, with the high demand for image recording by the ink jet recording technique, the performance required for the ink is also high, and urea is contained in the ink as a humectant. Furthermore, in order to improve the water resistance of the recorded matter, a poorly water-soluble dye is used as a coloring material, and the ink is configured to contain an alkali salt in order to dissolve this dye.

  As described above, when urea or an alkali salt is contained in the ink, the ink exhibits a relatively high alkalinity. However, the high alkali ink has an ink flow path wall that is a cured product of an epoxy resin like a polar solvent. Easy to swell. Therefore, in the conventional ink jet recording head manufactured by the above-described manufacturing method using a highly alkaline ink, the ink flow path wall may be deformed by volume swelling due to the ink absorption, and a desired discharge state may not be obtained. The flow path wall may be peeled off from the substrate, which is not necessarily sufficient from the viewpoint of the reliability of the ink jet recording head.

In response to the above-described problem, Patent Document 7 discloses that the amount of ink absorbed on the ink flow dew wall can be reduced by adding a compound having a fluorocarbon to the resin composition serving as the ink flow path wall. .
JP-A-6-286149 JP-A-3-184868 Japanese Patent Laid-Open No. 60-161973 Japanese Unexamined Patent Publication No. 63-221121 JP-A 64-009216 JP-A-2-140219 JP-A-8-290572

  However, along with the development of recording technology using inkjet recording heads, it is essential to further increase the alkali of the ink and form a tiny orifice. The addition of a compound having a fluorocarbon alone cures the resin composition that becomes the ink flow path wall. There is a possibility that the influence of volume swelling due to ink absorption of objects may be at a level that cannot be ignored.

  As described above, the above-described ink jet recording head manufacturing method has a technical problem of further reducing the amount of swelling of the ink flow path wall when a very small orifice is produced or when a highly alkaline ink is used.

  The present invention solves the above-described problems in the prior art, and provides an ink jet recording head that can stably discharge for a long time even when a high alkali ink is used or a tiny orifice is produced, and a method for manufacturing the same. Objective.

  To achieve the above object, the present invention provides an ejection port for ejecting ink, an ink channel wall that communicates with the ejection port and forms an ink channel including an ink ejection pressure generating element, and an ink ejection As an ink jet recording head having a substrate on which a pressure generating element is formed, the constituent member of the ink flow path wall is made of a cured product of a resin constituent including at least an organic filler.

  The present invention also includes a step of forming an ink flow path pattern with a soluble resin on a substrate on which an ink discharge pressure generating element is formed, and a covering resin layer serving as an ink flow path wall on the soluble resin layer An ink jet recording head comprising: a step of forming an ink discharge port by photolithography above an ink discharge pressure generating element; and a step of eluting the dissolvable resin layer to form an ink flow path In this manufacturing method, the coating resin layer serving as the ink flow path wall has an organic filler.

  According to the present invention, when an organic filler is added to the resin composition that is a constituent material of the ink flow path wall, the ink absorption amount can be reduced due to the effect of improving the resin density. In addition to organic fillers, similar effects can be expected with inorganic fillers, but due to the difference in specific gravity between organic fillers and inorganic fillers, the stability of the resin (filler sedimentation in the resin solution) is better when organic fillers are added. . Therefore, by adding the organic filler to the resin composition that is a constituent material of the ink flow path wall, the volume swelling amount due to the ink absorption of the ink flow path wall is reduced. A highly reliable ink jet recording head in which the flow path wall is not dissolved in the ink can be obtained.

  The material of the organic filler in the present invention is not particularly limited, but polyimide, polyamide, and the like are suitable from the viewpoint of solvent resistance (ink resistance), heat resistance, and the like.

  The organic filler in the present invention preferably has a particle size of 250 nm or less. This is because it is essential that the particle size of the organic filler be smaller than the exposure wavelength when photolithography is used to form the orifice. If an organic filler having a particle diameter larger than the exposure wavelength is used, a high-definition pattern of the resin composition cannot be obtained when photolithography is performed, and an orifice having a uniform shape cannot be formed. Moreover, when adding the said organic filler to the resin composition used as an ink flow path wall, it is desirable that the content is 1 to 10%. That is, if the content of the organic filler is less than 1%, desired performance cannot be exhibited, and if the content of the organic filler exceeds 10%, the resin composition that becomes the ink flow path wall is cured. This is because there is a risk of obstruction.

  In addition, additives and the like can be appropriately added to the resin composition serving as the ink flow path wall as necessary. For example, a silane coupling agent may be added in order to obtain further adhesion with the substrate.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1>
In the present embodiment, a photocurable resin composition containing an organic filler was placed on a substrate, and the volume swelling amount of the resin cured product by ink absorption was measured by an acceleration test.

First, a 6-inch Si wafer was prepared as a substrate, and a 1.0 μm SiO ₂ layer was formed by thermal oxidation. Next, a resin composition described in Table 1 dissolved in an appropriate solvent was formed into a film by spin coating, and the coating solvent was evaporated by baking at 90 ° C. for 5 minutes to form a film having a thickness of 20 μm.

Next, using Canon mask aligner MPA600, the resin composition on the substrate was patterned at an exposure amount of 3000 mJ / m ^2. After exposure, the resin composition was heated on a hot plate at 90 ° C. for 4 minutes and then developed with a methyl isobutyl ketone / xylene mixed solvent. Then, the main curing was performed by heating at 200 ° C./1 hour. Thus, a line & space pattern having a length of 5 cm and a width of 20 μm and an orifice pattern of φ10 μm were formed.

  Next, these samples were immersed in an ink composed of ethylene glycol / urea / isopropyl alcohol / black dye / water = 5/3/2/3/87 (60 ° C./1 week), and the dimensional change of the line pattern width and orifice area was measured. Observed.

  After completion of ink immersion, the sample was washed with water and blow-dried, and then the line pattern width and orifice area were measured. As shown in Table 2, the resin composition lines of Experimental Examples 1 and 2 having the constitution of the present invention were measured. For the sample having the & space pattern and the orifice pattern on the Si wafer, the line pattern width change rate was + 3% and the orifice area change rate was -3%. On the other hand, in Comparative Example 1, the change rates were +8 and −8%, respectively.

  From this result, it was confirmed that the cured product of the resin composition containing the organic filler of the present invention is an excellent material having a small volume swelling amount due to ink absorption and having no problem in adhesion to the substrate.

<Embodiment 2>
In Embodiment 1, an ink jet recording head having a minimal orifice was produced by using the resin composition shown in Table 1 as an ink flow path wall constituting member by the following production method, and the image change when ink was absorbed was evaluated. . Hereinafter, description will be given with reference to the drawings.

As shown in FIG. 1, an electrothermal conversion element (TaN) ₂ is arranged as an ink pressure generating element on an Si wafer substrate 1 having a crystal axis (100) provided with an ink supply port forming mask 3 and a SiN layer as a protective film. 4. A Ta layer 5 was formed. The electrothermal conversion element 2 is connected to a control signal input electrode for operating the element (not shown). FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG.

  Next, a layer 6 made of polyetheramide as an adhesion layer was formed on the substrate 1 with a thickness of 2.0 μm by the following method. For the polyetheramide layer, HIMAL1200 manufactured by Hitachi Chemical Co., Ltd. was used and applied onto the substrate 1 with a spinner and baked at 100 ° C./30 minutes + 250 ° C./1 hour.

Next, patterning is performed on the HIMAL using a positive resist OFPR800 manufactured by Tokyo Ohka Kogyo Co., Ltd., the HIMAL layer is patterned by O ₂ plasma ashing using the OFPR pattern as a mask, and finally the OFPR used as the mask. The adhesion layer shown in FIG. 3 was formed by peeling the pattern.

  Next, as shown in FIG. 4, an ink flow path pattern made of a positive resist ODUR1010 manufactured by Tokyo Ohka Kogyo Co., Ltd. was formed on the substrate 1.

  Further, a solution 8 prepared by dissolving the resin composition shown in Table 1 in an appropriate solvent was formed on the substrate 1 by a solvent coat, and a minimum orifice 9 (φ8 μm) was formed by photolithography (see FIG. 5).

  Next, the substrate 1 was subjected to Si anisotropic etching to form an ink supply port 10 (see FIG. 6).

  Next, the ink flow path pattern 7 composed of the Si film and the ODUR on the ink supply port is removed, and in addition, in order to completely cure the epoxy resin 8 which is a nozzle constituent member, heating is performed at 200 ° C./1 hour to perform ink jet recording. A head was obtained (see FIG. 7).

  Next, when the above-described highly alkaline ink was used for the test printing of 50000 sheets with the ink jet recording head produced, the volume swelled by the ink-absorbing ink was obtained using the resin composition of Comparative Example 1 as a constituent member of the ink flow path wall. Due to the large orifice deformation, slight image distortion occurred. On the other hand, when the resin composition of Experimental Examples 1 and 2 was used as the ink flow path wall constituting member, the image was not disturbed.

  As described above, in any of the embodiments according to the present invention, it is possible to obtain a highly reliable ink jet recording head in which volume swelling due to ink absorption on the ink flow path wall is small and stable ink ejection is possible for a long time.

It is explanatory drawing which shows the manufacturing method of the inkjet recording head of this invention. It is explanatory drawing which shows the manufacturing method of the inkjet recording head of this invention. It is explanatory drawing which shows the manufacturing method of the inkjet recording head of this invention. It is explanatory drawing which shows the manufacturing method of the inkjet recording head of this invention. It is explanatory drawing which shows the manufacturing method of the inkjet recording head of this invention. It is explanatory drawing which shows the manufacturing method of the inkjet recording head of this invention. It is explanatory drawing which shows the manufacturing method of the inkjet recording head of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Si substrate 2 Ink discharge pressure generating element 3 Ink supply port 4 SiN film 5 Ta film 6 Adhesion film 7 Ink flow path pattern 8 Nozzle component 9 Ejection port 10 Ink supply port

Claims (10)

An ejection port for ejecting ink, an ink channel wall that communicates with the ejection port and forms an ink channel including an ink ejection pressure generating element, and a substrate on which the ink ejection pressure generating element is formed An inkjet recording head,
An ink jet recording head, wherein the constituent member of the ink flow path wall is made of a cured product of a resin constituent containing at least an organic filler.   2. The ink jet recording head according to claim 1, wherein the organic filler has a particle size of 250 nm or less.   3. The ink jet recording head according to claim 1, wherein the organic filler is polyimide fine particles or polyamide fine particles.   The inkjet recording head according to claim 1, wherein the content of the organic filler contained in the nozzle forming member is 1 to 10 wt% with respect to the solid content of the nozzle forming member.   The ink jet recording head according to claim 1, wherein the coating resin layer serving as the ink flow path wall contains a cationic photopolymerization initiator and an epoxy resin. Forming an ink flow path pattern with a soluble resin on a substrate on which an ink discharge pressure generating element is formed; forming a covering resin layer serving as an ink flow path wall on the soluble resin layer; In a method of manufacturing an ink jet recording head, comprising: a step of forming an ink discharge port by photolithography above an ink discharge pressure generating element; and a step of eluting the dissolvable resin layer to form an ink flow path.
A method for manufacturing an ink jet recording head, wherein the coating resin layer serving as the ink flow path wall has an organic filler.   The method of manufacturing an ink jet recording head according to claim 6, wherein a particle size of the organic filler is 250 nm or less.   8. The method of manufacturing an ink jet recording head according to claim 6, wherein the organic filler is polyimide fine particles or polyamide fine particles.   The method of manufacturing an ink jet recording head according to claim 6, wherein the content of the organic filler contained in the nozzle forming member is 1 to 10 wt% with respect to the solid content of the nozzle forming member. .   10. The method of manufacturing an ink jet recording head according to claim 6, wherein the coating resin layer serving as the ink flow path wall contains a cationic photopolymerization initiator and an epoxy resin.

Images