JP2012081601A - Inkjet head and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet head having an outlet with high shape accuracy, which can accurately impact finer liquid droplets than before.SOLUTION: There is provided the inkjet head having the outlet of ink on which a nozzle layer and a liquid-repellent layer are formed. The liquid-repellent layer is a layer with a liquid-repellent layer material hardened, which contains a thermal cationic initiator having an anionic part in which diffusion of cation is small. Consequently, the outlet with high shape accuracy can be achieved.

Description

  The present invention relates to an inkjet head in which the surface of an ejection port for ejecting ink is subjected to liquid repellent treatment and a method for manufacturing the same.

  As a manufacturing method of an ink jet head in which a liquid repellent layer is formed on a nozzle layer in which discharge ports are formed, Patent Document 1 discloses the following method. First, a nozzle layer containing a cationic polymerizable resin is formed on a substrate. Thereafter, a liquid repellent layer which is a condensation product formed from a hydrolyzable silane compound having a fluorine-containing group and a hydrolyzable silane compound having a cationic polymerizable group is formed on the nozzle layer. At this time, heat treatment is performed to remove the coating solvent in the liquid repellent layer. Next, in order to form an ejection port for ejecting ink, pattern exposure is performed in a desired shape using a mask. Thereafter, an unexposed portion is removed by development processing to form an ejection port. It is also disclosed that a photocationic initiator may be added to the liquid repellent layer.

JP-T-2007-518587

  According to Patent Document 1, even when no photocationic initiator is added to the liquid repellent layer, the liquid repellent layer can be cured by the action of the photocationic initiator added to the cationic polymerizable resin that is the nozzle layer. Is possible. Furthermore, by adding a photocationic initiator to the liquid repellent layer, the exposure margin of light irradiation necessary for curing the liquid repellent layer can be increased. These are sufficient to satisfy the image quality of an image output by an inkjet head currently in a general home or office.

  However, in the future, in order to realize further higher image quality of the output image, when the droplet size of the flying droplet is made smaller than the current size, the shape of the discharge port is required to be higher than ever. As the droplets become smaller, the kinetic energy of the flying droplets becomes smaller and is more susceptible to external influences. If the ejection openings are non-uniform, the ejection direction may not be determined due to the influence. In the method described in Patent Document 1, when the exposure amount of pattern exposure is large, a minute discharge port deformation occurs due to reflection of irradiation light generated by a step on the substrate surface, and the perfect circle pattern becomes slightly elliptical There is. However, this minute deformation of the discharge port has not been a problem as long as the size of the discharge port up to the present state, but can be a problem in a small discharge port for landing a further small droplet with high accuracy. In the formation of the micro discharge port, it is necessary to suppress the influence of the reflection of the irradiation light from the substrate by significantly reducing the exposure amount from the current method in the conventional method. However, when the sensitivity of the liquid repellent layer is lower than the sensitivity of the nozzle layer, it is difficult to cure the liquid repellent layer if the exposure amount is significantly reduced. Further, even when a photocationic initiator is added to the liquid repellent layer, if the exposure amount is significantly reduced from the current level, the amount of cations generated is very small, and similarly, the liquid repellent layer is difficult to cure.

  On the other hand, it is conceivable to add a thermal cation initiator to the liquid repellent layer. In this case, it is possible to cure the liquid repellent layer to some extent in advance by applying a heat treatment after applying the liquid repellent layer raw material, and the liquid repellent layer can be formed even if the exposure amount is significantly reduced from the current level. Can be cured sufficiently. However, when a thermal cation initiator having a large cation diffusion distance is used, the cation diffuses from the liquid repellent layer to the nozzle layer due to the heat treatment, so that the cation reaches the pattern portion of the discharge port to be originally removed. Spread. As a result, the nozzle layer portion to be removed is hardened near the edge of the discharge port due to the synergistic effect with the diffusion of cations emitted from the nozzle layer, resulting in a problem that the discharge port is greatly deformed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet head having a discharge port with high shape accuracy and capable of landing fine droplets with high accuracy, and a method for manufacturing the same.

An inkjet head according to the present invention is an inkjet head having a nozzle layer in which an ejection port for ejecting ink is formed, and a liquid repellent layer formed on the nozzle layer. The following formula (1)
_{R f -Si (R 1) b} X (3-b) (1)
(R _f is a non-hydrolyzable substituent having 1 to 30 fluorine atoms bonded to a carbon atom, R ₁ is a non-hydrolyzable substituent, X is a hydrolyzable substituent, b is 0 to 2 A hydrolyzable silane compound having a fluorine-containing group represented by the following formula (2):
_{R c -Si (R 1) b} X (3-b) (2)
(R _c represents a non-hydrolyzable substituent having a cationic polymerizable group, and R ₁ , X and b are as defined in the above formula (1)), and a hydrolyzable silane having a cationic polymerizable group A siloxane compound obtained by condensing a compound with the following formula (3)
^{_{(R 2 -Y-) m -Z -}} - (- F) n (3)
(Z is one atom selected from the group consisting of carbon, nitrogen atom, phosphorus atom and a boron atom, Y is _{-S (= O) 2 -,} - CF 2 -O -, - CF 2 -C (= O ) —, —CF ₂ —C (═O) —O—, —CF ₂ —O—C (═O) — and one group selected from the group consisting of a single bond, R ₂ may be substituted with fluorine. M and n are integers of m + n = 3 and n = 0 to 2 when Z is a carbon atom, m + n = 2 and n = 0 or 1, when Z is a nitrogen atom, When Z is a phosphorus atom, m + n = 6 and n = 0 to 6 and when Z is a boron atom, m + n = 4 and n = 0 to 3) It is a layer obtained by curing a liquid repellent layer material containing a thermal cation initiator.

  According to the present invention, it is possible to provide an inkjet head having a discharge port with high shape accuracy capable of landing fine droplets with high accuracy and a manufacturing method capable of stably producing the same.

It is a cross-sectional schematic diagram which shows an example of the inkjet head which concerns on this invention. It is a cross-sectional schematic diagram which shows an example of the manufacturing method of the inkjet head which concerns on this invention.

[Inkjet head]
FIG. 1 is a schematic cross-sectional view of an inkjet head that is an embodiment of the present invention. The ink jet head shown in FIG. 1 includes an element substrate 1 having a plurality of heating elements 2 that generate energy for discharging ink, and a nozzle layer 3 formed on the element substrate 1 by a photolithography process. Further, the nozzle layer 3 is formed with a foaming chamber 5 which is a region where ink is foamed by the energy provided by the ejection port 4 and the heating element 2 for ejecting ink. A liquid repellent layer 6 is formed on the nozzle layer 3. In addition, the element substrate 1 is formed with an ink flow path 7 for sending ink to the foaming chamber 5.

(Liquid repellent layer)
The liquid repellent layer according to the present invention has the following formula (1):
_{R f -Si (R 1) b} X (3-b) (1)
A hydrolyzable silane compound having a fluorine-containing group represented by formula (2):
_{R c -Si (R 1) b} X (3-b) (2)
A siloxane compound obtained by condensing a hydrolyzable silane compound having a cationically polymerizable group represented by formula (3):
^{_{(R 2 -Y-) m -Z -}} - (- F) n (3)
And a thermal cation initiator having an anion moiety represented by the formula:

In the hydrolyzable silane compound having a fluorine-containing group represented by the formula (1), R _f is a non-hydrolyzable substituent having 1 to 30 fluorine atoms bonded to a carbon atom. R _f is preferably CF ₃ (CF ₂ ) ₁ -A-. l is an integer, preferably 0 to 20, more preferably 3 to 15, and still more preferably 5 to 10. A preferably contains no more than 10 carbon atoms, such as methylene, ethylene, propylene, butylene, methyleneoxy, ethyleneoxy, propyleneoxy and butyleneoxy, etc., divalent alkylene having no more than 6 carbon atoms More preferably, it is a group or an alkyleneoxy group. Most preferred is ethylene. R ₁ is a non-hydrolyzable substituent. Examples of R ₁ include a methyl group. X is a hydrolyzable substituent. Examples of X include an alkoxy group. X is preferably an alkoxy group, more preferably methoxy or ethoxy. b is an integer of 0 to 2. b is preferably 0 or 1, particularly preferably 0.

Examples of the hydrolyzable silane compound having a fluorine-containing group represented by the formula (1) include the following compounds. _{CF 3 -C 2 H 4 -SiX 3} ; C 2 F 5 -C 2 H 4 -SiX 3; C 4 F 9 -C 2 H 4 -SiX 3; C 6 F 13 -C 2 H 4 -SiX 3; _{C 8 F 17 -C 2 H 4} -SiX 3; C 10 F 21 -C 2 H 4 -SiX 3. X is a methoxy group or an ethoxy group. The hydrolyzable silane compound having a fluorine-containing group represented by the formula (1) is not limited to these compounds. Moreover, the hydrolyzable silane compound which has a fluorine-containing group represented by the said Formula (1) may use only 1 type, and may use 2 or more types together.

In the hydrolyzable silane compound having a cationically polymerizable group represented by the formula (2), R _c represents a non-hydrolyzable substituent having a cationically polymerizable group. As the cationic polymerizable organic group, a cyclic ether group represented by a vinyl ether group, an epoxy group, an oxetane group, or the like can be used. An epoxy group is preferable from the viewpoint of availability and reaction control. Examples of R _c include a glycidoxypropyl group and an epoxycyclohexylethyl group. In the formula (2), R ₁ , X and b have the same meanings as the formula (1), and the preferred ranges are also the same.

  Examples of the hydrolyzable silane compound having a cationically polymerizable group represented by the formula (2) include glycidoxypropyltrimethoxysilane, glycidoxypropyltriethoxysilane, epoxycyclohexylethyltrimethoxysilane, and epoxycyclohexyl. Examples thereof include ethyltriethoxysilane. The hydrolyzable silane compound having a cationically polymerizable group represented by the formula (2) is not limited to these compounds. Moreover, only 1 type may be used for the hydrolysable silane compound which has a cationically polymerizable group represented by the said Formula (2), and it may use 2 or more types together.

  The liquid repellent layer raw material according to the present invention includes a hydrolyzable silane compound having a fluorine-containing group represented by the formula (1) and a hydrolyzable silane compound having a cationic polymerizable group represented by the formula (2). And a siloxane compound obtained by condensation. The siloxane compound is prepared by hydrolysis reaction of the compound represented by the formula (1) and the compound represented by the formula (2) in the presence of water. The degree of condensation of the siloxane compound can be appropriately controlled by the reaction temperature, pH and the like. Furthermore, it is possible to control the degree of condensation as a result of the hydrolysis reaction using a metal alkoxide as a catalyst for the hydrolysis reaction. As the metal alkoxide, aluminum alkoxide, titanium alkoxide, zirconium alkoxide, and complexes thereof (acetylacetone complex and the like) are preferable. In the present invention, the hydrolyzable silane compound having a fluorine-containing group represented by the formula (1) and the hydrolyzable silane compound having a cationic polymerizable group represented by the formula (2) Different compounds are used.

  The liquid repellent layer raw material according to the present invention includes a thermal cation initiator having an anion moiety represented by the formula (3). Since the thermal cation initiator has a specific anion portion, the cation diffusion is small, and the cation diffusion from the liquid repellent layer to the nozzle layer can be suppressed in the heating step described later. Thereby, unnecessary hardening of the nozzle layer portion removed for forming the discharge port can be suppressed, and a discharge port having a desired shape can be formed.

In the formula (3), Z represents one atom selected from the group consisting of a carbon atom, a nitrogen atom, a phosphorus atom and a boron atom. Y represents —S (═O) ₂ —, —CF ₂ —O—, —CF ₂ —C (═O) —, —CF ₂ —C (═O) —O—, —CF ₂ —O—C ( One group selected from the group consisting of ═O) — and a single bond is shown. R ₂ represents a hydrocarbon group which may be substituted with fluorine. Examples of R ₂ include CF ₃ — and C ₂ F ₅ —. When m is 2 or more, R ₂ may be bonded to each other. m and n are each an integer of m + n = 3 and n = 0 to 2 when Z is a carbon atom, m + n = 2 and n = 0 or 1, when Z is a nitrogen atom, and when Z is a phosphorus atom, When m + n = 6 and n = 0 to 6 and Z is a boron atom, m + n = 4 and n = 0 to 3 are shown.

  Examples of the thermal cation initiator having an anion moiety represented by the formula (3) include compounds represented by the following formulas (3-a) to (3-h).

  Among these, (3-a) and (3-b) are preferable. The thermal cation initiator is not limited to these compounds. Moreover, the said thermal cation initiator may use only 1 type, and may use 2 or more types together. In addition to the siloxane compound and the thermal cation initiator, ethanol or the like may be included in the liquid repellent layer raw material as a coating solvent.

(Nozzle layer)
Although it does not specifically limit as a nozzle layer raw material, It is preferable to use a photopolymerizable material from a viewpoint of hardening an exposure part by pattern exposure so that it may mention later. For example, a material containing an epoxy resin, a silane coupling agent, and a photocation initiator can be used.

[Inkjet head manufacturing method]
Hereinafter, an example of a method for manufacturing an inkjet head according to the present invention will be described with reference to FIG. An element substrate 1 having a plurality of heating elements 2 that generate energy for ejecting ink is prepared (FIG. 2A). A mold material 8 to be the foaming chamber 5 is formed on the element substrate 1 (FIG. 2B). As the mold material 8, in order to prevent the collapse of the nozzle layer 3 when the nozzle layer 3 is formed on the mold material 8, it is preferable to use a positive resist, particularly a photodegradable positive resist having a relatively large molecular weight. Next, the nozzle layer material is applied onto the mold material 8 and the element substrate 1 to form the nozzle layer material layer 3 (FIG. 2C). The nozzle layer material layer 3 can be produced by applying the nozzle layer material by a spin coating method or a direct coating method. Next, the liquid repellent layer raw material layer 6 is formed by applying the liquid repellent layer raw material on the nozzle layer raw material layer 3 (FIG. 3D). The liquid repellent layer raw material layer 6 can be produced by the same method as the nozzle layer raw material layer 3. Thereafter, heat treatment is performed. By the heat treatment, the coating solvent in the liquid repellent layer raw material layer 6 is removed, and cations are generated by the action of the thermal cation initiator, and the liquid repellent layer raw material layer 6 starts to be cured. The heating temperature in the heat treatment is preferably 50 to 100 ° C. Moreover, it is preferable that the thickness of the liquid repellent layer raw material layer 6 after heat processing is 0.05-1.0 micrometer.

  Next, ultraviolet rays 10 are irradiated onto the cured regions of the nozzle layer raw material layer 3 and the liquid repellent layer raw material layer 6 using a mask 9 to perform pattern exposure (FIG. 3E). Thereby, the exposed portions of the nozzle layer raw material layer 3 and the liquid repellent layer raw material layer 6 can be cured to form the nozzle layer 3 and the liquid repellent layer 6. Although it does not specifically limit as a wavelength of the ultraviolet-ray 10, For example, i line | wire can be used. The exposure amount can sufficiently cure the nozzle layer raw material layer 3 and the liquid repellent layer raw material layer 6 and can sufficiently reduce the influence of the reflected light from the element substrate 1 generated by the level difference on the surface of the element substrate 1. Can be appropriately selected. Thereby, deformation of the discharge port can be suppressed even in the formation of a small discharge port. Thereafter, heat treatment is performed as necessary to promote the curing reaction of the exposed portion. Next, the discharge port 4 is formed in the nozzle layer 3 and the liquid repellent layer 6 by removing an unexposed portion by development processing (FIG. 3F). Since the thermal cation initiator according to the present invention has an anion portion in which cation diffusion is very small, the unexposed portion of the nozzle layer raw material layer 3 is not cured, and only the liquid repellent layer raw material layer 6 is cured. The unexposed portion of the nozzle layer raw material layer 3 is developed and at the same time the unexposed portion of the liquid repellent layer raw material layer 6 is removed, so that the smooth edge portion without unevenness and the mask 9 shape are very beautiful. A discharge port 4 having a similar shape can be formed. Next, the ink flow path 7 is formed on the element substrate 1 by a known method (FIG. 3G), and the mold material 8 is dissolved and removed (FIG. 3H). The ink jet head is completed through the above steps.

  Examples of the present invention will be described below, but the present invention is not limited thereto. “Part” means “part by mass”.

[Example 1]
In this example, a photopolymerizable material having the composition shown in Table 1 was used as the nozzle layer material.

In this example, the liquid repellent layer material includes a condensation product of C ₁₀ F ₂₁ —C ₂ H ₄ —SiX ₃ (X is an ethoxy group) and γ-glycidoxypropyltriethoxysilane represented by the following formula ( The material mixed with the thermal cation initiator shown in 4) was used. Further, ethanol was used as a coating solvent for the liquid repellent layer 6 raw material.

In this example, the nozzle layer 3 and the liquid repellent layer 6 were formed by the method shown in FIG. 2 to produce an ink jet head. First, a mold material 8 to be a foaming chamber 5 was formed on an element substrate 1 having a plurality of heating elements 2 (FIGS. 2A and 2B). Next, the nozzle layer material was applied to form a nozzle layer material layer 3 (FIG. 2C). Thereafter, the liquid repellent layer raw material was applied to form the liquid repellent layer raw material layer 6 (FIG. 2D). Thereafter, a heat treatment was performed at 70 ° C. for 3 minutes in order to remove the coating solvent in the liquid repellent layer raw material layer 6 and to start curing of the liquid repellent layer raw material layer 6. Next, the ultraviolet rays 10 were irradiated using the mask 9 with respect to the hardening area | region of the nozzle layer raw material layer 3 and the liquid repellent layer raw material layer 6 (FIG.2 (e)). In this embodiment, the ultraviolet ray 10 is an exposure with a single wavelength by i-line. Thereafter, heat treatment was performed at 90 ° C. for 4 minutes. Next, the unexposed portion was removed by dissolution to form a circular discharge port 4 (FIG. 2 (f)). Thereafter, an ink flow path 7 was formed on the element substrate 1 (FIG. 2G). Next, the mold material 8 was dissolved and removed to form the foaming chamber 5 (FIG. 2 (h)). Thereby, an ink jet head was obtained. In this example, four types of ink jet heads having an area of the circular discharge port 4 of 490 μm ² , 210 μm ² , 70 μm ² , and 35 μm ² were manufactured.

(Evaluation of shape of discharge port 4)
As the shape evaluation of the circular discharge port 4, an evaluation was performed based on the roundness of the circular discharge port 4. Even when the ejection port 4 is formed using the perfect circle mask 9, the ejection port 4 that is actually produced may be distorted due to the reflection from the unevenness of the base, and may not become a perfect circle. Therefore, the longest diameter and the shortest diameter of the formed discharge port 4 were measured and numerically expressed as roundness. Roundness is expressed by the longest diameter / shortest diameter, and was evaluated according to the following criteria.
A: 1 or more, less than 1.05 ○: 1.05 or more, less than 1.1 Δ: 1.1 or more, less than 1.2 x: 1.2 or more.

(Water repellency evaluation)
As an evaluation of the water repellency of the liquid repellent layer 6, an evaluation was performed based on a dynamic receding contact angle of pure water on the surface of the liquid repellent layer 6. Evaluation was performed according to the following criteria.
A: 90 ° or more ○: 75 ° or more, less than 90 ° Δ: 65 ° or more, less than 75 ° x: less than 65 °

Table 2 shows the evaluation results of the four types of ink jet heads. The discharge port area in Table 2 is large: 490 μm ² , medium: 210 μm ² , small: 70 μm ² , and minute: 35 μm ² .

[Comparative Example 1]
Four types of inkjet heads were prepared and evaluated in the same manner as in Example 1 except that the thermal cation initiator was not mixed with the liquid repellent layer raw material. The results are shown in Table 2.

[Comparative Example 2]
Four types of inkjet heads were prepared and evaluated in the same manner as in Example 1 except that a photocationic initiator having antimony hexafluoride as an anion portion was used instead of the thermal cation initiator represented by the formula (4). did. The results are shown in Table 2.

[Comparative Example 3]
Four types of inkjet heads were prepared and evaluated in the same manner as in Example 1 except that a thermal cation initiator having antimony hexafluoride as an anion portion was used instead of the thermal cation initiator represented by the formula (4). did. The results are shown in Table 2.

  Compared with Comparative Examples 1, 2, and 3, Example 1 was in a good state in both shape and water repellency even when the area of the discharge port 4 was small, and the effects of the present invention could be confirmed.

1 element substrate 2 heating element 3 nozzle layer (nozzle layer raw material layer)
4 Discharge port 5 Foaming chamber 6 Liquid repellent layer (liquid repellent layer raw material layer)
7 Ink supply port 8 Mold material 9 Mask 10 UV

Claims (4)

An ink jet head having a nozzle layer in which a discharge port for discharging ink is formed, and a liquid repellent layer formed on the nozzle layer,
The liquid repellent layer has the following formula (1)
_{R f -Si (R 1) b} X (3-b) (1)
(R _f is a non-hydrolyzable substituent having 1 to 30 fluorine atoms bonded to a carbon atom, R ₁ is a non-hydrolyzable substituent, X is a hydrolyzable substituent, b is 0 to 2 A hydrolyzable silane compound having a fluorine-containing group represented by the following formula (2):
_{R c -Si (R 1) b} X (3-b) (2)
(R _c represents a non-hydrolyzable substituent having a cationic polymerizable group, and R ₁ , X and b are as defined in the above formula (1)), and a hydrolyzable silane having a cationic polymerizable group A siloxane compound obtained by condensing a compound with the following formula (3)
^{_{(R 2 -Y-) m -Z -}} - (- F) n (3)
(Z is one atom selected from the group consisting of carbon, nitrogen atom, phosphorus atom and a boron atom, Y is _{-S (= O) 2 -,} - CF 2 -O -, - CF 2 -C (= O ) —, —CF ₂ —C (═O) —O—, —CF ₂ —O—C (═O) — and one group selected from the group consisting of a single bond, R ₂ may be substituted with fluorine. M and n are integers of m + n = 3 and n = 0 to 2 when Z is a carbon atom, m + n = 2 and n = 0 or 1, when Z is a nitrogen atom, When Z is a phosphorus atom, m + n = 6 and n = 0 to 6 and when Z is a boron atom, m + n = 4 and n = 0 to 3) An inkjet head, which is a layer obtained by curing a liquid repellent layer material containing a thermal cation initiator. The anion part of the thermal cation initiator is represented by the following formula (3-a)

The inkjet head of Claim 1 represented by these. The anion part of the thermal cation initiator is represented by the following formula (3-b)

The inkjet head of Claim 1 represented by these. It is a manufacturing method of the ink-jet head according to any one of claims 1 to 3,
A step of applying the liquid repellent layer raw material on the nozzle layer raw material layer including the photopolymerizable nozzle layer raw material to form the liquid repellent layer raw material layer, and heating the nozzle layer raw material layer and the liquid repellent layer raw material layer A process step, pattern exposure of the nozzle layer raw material layer and the liquid repellent layer raw material layer to cure an exposed portion, and a nozzle layer and a liquid repellent layer; Forming a discharge port in the nozzle layer and the liquid repellent layer.

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