JPH0789077A - Surface treating method for ink jet recording head - Google Patents

Abstract

PURPOSE:To improve durability of a film by coating an ink jet orifice surface with resin composition in which inorganic or organic fine particles are filled in amorphous thermoplastic resin having a perfluoro structure, and adding filler in liquid repellency agent. CONSTITUTION:An ink jet orifice surface is coated with resin composition in which inorganic or organic fine particles are filled in amorphous thermoplastic resin having perfluoro structure. As the polymer compound having the perfluoro structure, amorphous thermoplastic resin having a perfluoroheterocycle structure is used. As the inorganic filler to be filled therein, titanium oxide, aluminum oxide, etc., is used, and as the organic filler, polyacrylamide, etc., is used. Then, a surface treating method adds to disperse perfluoro compound soluble in specific solvent or fluorine-containing compound insoluble in solvent in perfluoro compound soluble in general organic solvent thereby to improve its mechanical strength without reducing water repellency continuity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head of an ink jet recording apparatus for ejecting and ejecting a recording liquid, which is generally called ink, as small droplets from an ejection port and adhering the droplets to a recording surface. The present invention relates to a surface treatment of the ink ejection port surface provided with the ink ejection port.

[0002]

2. Description of the Related Art Conventionally, an ink jet recording apparatus for recording recording information by ejecting a recording liquid (ink) from an orifice (ejection port) of a recording head has been used as a recording apparatus excellent in low noise and high speed recording. Are known.

FIG. 1 is a developed perspective view illustrating the configuration of a normal ink jet recording head.

In this recording head, a discharge pressure generating element 12 is installed on a substrate 11 formed of glass, ceramics or the like, and the discharge pressure generating element is formed by patterning the photosensitive resin cured film 13 by photolithography. A liquid passage 15 and an orifice 14 corresponding to 12 and a liquid chamber 16 are formed.

On the photosensitive resin cured film 13, for example, a top plate 1 made of glass, ceramics or metal.
7 is laminated and fixed by an adhesive 19.

A recording liquid supply port 18 is formed on the top plate 17.

In the recording head having such a configuration, the physical properties (physical characteristics) of the surfaces of the substrate 11, the photosensitive resin cured film 13, and the top plate 17 surrounding the orifice 14 make the recording liquid always stable from the orifice 14. It is extremely important for discharging.

That is, if the recording liquid is spilled into the outer peripheral surface of the orifice 14 (orifice peripheral portion) and a liquid pool is generated in a part thereof, when the recording liquid in the flow path 15 is discharged from the orifice 14. , The flight direction is separated from the regular predetermined direction, and further, due to the instability of the liquid pool state, the flight direction is disturbed every time it is ejected, and thus stable liquid ejection can be performed. Without this, good recording cannot be performed.

Furthermore, when the entire outer peripheral surface of the orifice 14 is covered with a film of the recording liquid, a so-called splash phenomenon occurs and the recording liquid is scattered, so that stable recording cannot be performed. Further, if the liquid pool covering the outer peripheral surface of the orifice becomes large, the liquid ejection of the recording head may even become impossible.

Further, in the ordinary recording head as shown in FIG. 1, different materials such as silicon (substrate 1), glass (top plate 17) and resin (photosensitive resin cured film 13) are used. There are many. Then, in the peripheral portion of the recording liquid and the orifice, leakage occurs from the portion of the most leaky material of these three kinds. With respect to ordinary ink (recording liquid), glass has the lowest interfacial tension with the ink among the above-mentioned three kinds of materials, and therefore ink leaks from that portion. The glass portion is a material that is usually used because it is preferable in manufacturing and performance of the head, and it is not preferable in manufacturing, performance, and cost to use another material for the purpose of preventing ink leakage.

As described above, in the conventional recording head, if the recording liquid remains in the peripheral portion of the orifice, stable ejection cannot be performed. Moreover, this tendency becomes extremely remarkable when high-definition recording is performed by increasing the nozzle density or when driving at a high frequency, that is, when high-speed recording is aimed at, in order to improve the performance of the recording head. It's a big problem.

Therefore, as shown in FIG. 1, a so-called liquid-repellent treatment is applied to at least the peripheral portion of the orifice 14 to form a liquid-repellent treated layer 20 that repels the ink, and there is a proposal to solve the above problem. , Has been published a lot from the past.

As one of the methods for solving these problems, silicone oil is conventionally used on the outer surface surrounding the discharge port,
Water repellency or oil repellency (liquid repellency) by treating with arabic rubber etc.
The method described in JP-B-48-36188 is disclosed.

However, these methods have poor durability because of poor adhesion to the base material such as glass, metal and resin forming the recording head, and the curing is only insufficient.
In addition, the liquid repellency is not sufficient. For example, even if a silicone-based substance exhibits liquid repellency with respect to water-based ink, it has almost no liquid repellency with respect to organic solvent-based inks such as alcohol-based, ketone-based, and ester-based inks. It was not liquid.

Further, there is an example in which the peripheral portion of the ejection port of the ink jet recording head is treated with fluoroalkylalkoxysilane to make it liquid repellent (Japanese Patent Laid-Open No. 8956969/56). It was necessary to perform a treatment such as heating at a temperature of 150 ° C. or higher for a long time or heating in a high pH solution (for example, an amine solution) that might destroy the material forming the ejection port. In addition, in the conventionally known ink jet recording head that has been subjected to a liquid repellent treatment, the adhesion between the orifice material and the water repellent resin is not sufficient, and the surface of the orifice material is chemically modified or the silane coupling agent treatment layer is used. Since it had to be provided between the orifice material and the water repellent resin, the processing was very complicated.

Further, when the ink is removed by the wiper, the mechanical durability of the liquid-repellent treatment layer is insufficient, so that the liquid-repellent layer may be scraped or peeled off by the wiper.

[0017]

The liquid-repellent treatment layer 20 formed on the ink jet recording head is not only good in water repellency, but is not the only liquid-repellent treatment layer that is used for recording with an ordinary ink jet recording apparatus. If it is not sufficient in terms of durability, it is not practical. The durability will be described below.

When the ink jet recording method is carried out, the peripheral edge of the orifice is always in contact with the recording liquid even if the peripheral edge of the orifice is subjected to the liquid repellent treatment.
It is usual to perform a recovery operation of wiping the orifice surface with an absorber such as polyurethane foam and absorbing the adhered ink. Therefore, the liquid-repellent treatment layer is required to have such adhesiveness that it is not peeled off even if it is rubbed by the absorber and abrasion resistance that is not broken. If the durability is insufficient, the liquid-repellent treatment layer gradually peels off or falls off while the head is in use, so that the liquid-repellent effect is not exhibited and stable ejection printing is achieved. I can not do it.

With respect to the durability required for such an ink jet recording head, a liquid repellent treatment layer formed of a conventional liquid repellent treatment agent may not be sufficient.

Further, when the member surrounding the orifice is made of a plurality of different materials like the ink jet head shown in FIG. 1, it is formed of a liquid repellent treatment agent having good adhesion to any of the materials. A liquid repellent treatment layer must be formed. The liquid-repellent layer formed of the conventional liquid-repellent agent may be insufficient in this respect.

The present applicant first applied for a liquid repellent treatment agent that solves such a problem. The specification of the application describes an inkjet recording head in which an amorphous thermoplastic fluororesin liquid-repellent layer is coated on a resin via a silane coupling agent or an organic titanate compound.

For example, the head (the substrate 11 is silicon,
When the top plate 17 is formed of glass, a liquid-repellent treatment layer of the resin cured film 13), and the above composition, the liquid-repellent durability and abrasion resistance are improved as compared with the conventional liquid-repellent water-treating agent. A treated layer is obtained.

However, the above composition has sufficient liquid repellency persistence and durability against blade wiping, but has many pretreatment steps for the orifice plate, which requires improvement in quality control and cost. An effective water repellent method is required.

The present invention has been made to solve such a problem, and its purpose is to improve the durability of the film by adding a filler to the liquid repellent treatment agent.

[0025]

The present invention is intended to solve the above problems, and its gist is a resin composition obtained by filling inorganic or organic fine particles in an amorphous thermoplastic resin having a perfluoro structure. In another aspect of the present invention, there is provided a surface treatment method for an ink jet recording head, characterized in that an object is applied to an ink jet orifice surface.

The present invention will be described in more detail below.

The polymer compound having a perfluoro structure used in the surface treatment method of the present invention is CTX-805X (manufactured by Asahi Glass Co., Ltd.), which is an amorphous thermoplastic resin having a perfluoroheterocyclic structure. CTX-80
5A (manufactured by Asahi Glass Co., Ltd.), Teflon AF (manufactured by DuPont), and the like. Further, as the inorganic fine particles to be filled in the amorphous thermoplastic resin of perfluoroheterocyclic structure, titanium oxide, aluminum oxide, tungsten, tungsten carbide, tungsten oxide, aluminum nitride, cerium polishing powder, cadmium oxide, iron oxide,
Examples thereof include silicon nitride, magnesium oxide, silicon dioxide, barium sulfate, kaolin clay, and spinel. Organic fine particles include polyacrylamide, nylon powder, polymethyl methacrylate, polyvinyl chloride, polystyrene, methyl methacrylate-styrene copolymer. , Acrylic acid-styrene copolymer and the like, and as other Teflon-based materials, Lubron L-2 (manufactured by Daikin Co., Ltd.), Lubron L-5F (manufactured by Daikin Co., Ltd.), TF9202 (manufactured by Hoechst Co., Ltd.), AD-1 (manufactured by Asahi Glass Co., Ltd.), Teflon 30J (manufactured by Mitsui DuPont), Microbar (manufactured by Sekisui Plastics Co., Ltd.), polyvinylbenzene, styrene-divinylbenzene copolymer, benzoguanamine resin eposter S (manufactured by Nippon Shokubai Co., Ltd.) Also, as a silicon type, Tospearl 1 3 (manufactured by Toshiba Silicone Co.), Tospearl 108 (Toshiba Silicone Co.), Trefil -925 (Toray Industries Co., Ltd.).

The particle size range of the fine particles is preferably 0.01 to 2 microns. If the particle size of the fine particles exceeds 2 μm, the liquid repellent effect deteriorates, and if it is less than 0.01 μm, durability such as abrasion resistance deteriorates, which is not preferable, and the above range is preferable.

By treating the surface of the filled fine particles with an organic titanate or a silane coupling agent to control the surface wettability, the dispersion stability of the polymer solution and the adhesion to the orifice material can be improved. Further, the silane coupling agent preferably contains at least one perfluoro group in its structure.

In the surface treatment method of the present invention, the water-repellent durability is reduced by adding and dispersing a solvent-insoluble fluorine-containing compound in a perfluoro compound soluble in a specific solvent or a perfluoro compound soluble in a general organic solvent. The mechanical strength can be improved.

As a method for coating the orifice surface with the resin filled with the fine particles, a casting method, a dipping method or a transfer method can be adopted.

Further, the present invention is not limited to the recording head as shown in FIG. 1, and any type of recording head can be applied to the present invention as long as the liquid is ejected from the ejection orifice.

[0033]

EXAMPLES The present invention will be described in more detail based on the following examples.

[Example 1] A bell eater (made by Kanebo) of an absorber was cut into a predetermined size, the absorber was dipped in a water repellent, and the pulled up product was pressed against the orifice surface of the grooved top plate. The coating was performed by moving it while moving.
As the liquid repellent treatment agent, a 5% solution of CYTOP CTX-805A (manufactured by Asahi Glass Co., Ltd.) was used as CT-solv. 100
(Boiling point 100 ° C., manufactured by Asahi Glass Co., Ltd.) diluted to 0.5% was used. As the filler, titanium oxide (Titanium Oxide P25 manufactured by Nippon Aerosil Co., Ltd.) surface-treated with 0.5% KP-801M and MF6 solution was added in an amount of 0.1% based on the amount of the CTX-805A solution.

Put the grooved top plate on the tray,
It was put in an oven at 150 ° C. for 2 and a half hours and dried by heat. At this time, since the temperature of the grooved top plate and the tray is raised to a predetermined temperature of 150 ° C. for 30 minutes after charging, the actual heat drying time is 2 hours.

After 2 and a half hours, it was gradually cooled, and when the temperature reached 80 ° C. or lower, it was taken out of the oven. A discharge orifice was formed by an excimer laser or the like on the grooved top plate that had been subjected to the liquid repellent treatment, and the discharge orifice was bonded to a substrate having a discharge pressure generating element.

[Example 2] Similar to Example 1, the same absorber was used and the grooved top plate was coated in the same manner. As the liquid repellent treatment agent, a 5 wt% solution of Cytop CTX-805A (manufactured by Asahi Glass) was used as CT-solv. 180 (boiling point 1
The product diluted to 0.5 wt% with 80 ° C., manufactured by Asahi Glass Co., Ltd. was used.

Titanium oxide (Tita) is used as the filler.
What was surface-treated with titanium polymer B-4 (made by Nippon Soda Co., Ltd.) was added 0.1% with respect to CTX-805A solution amount.

Put the grooved top plate on the tray,
It was put in an oven at 150 ° C. for 2 and a half hours and dried by heat. At this time, since the temperature of the grooved top plate and the tray is raised to a predetermined temperature of 150 ° C. for 30 minutes after charging, the actual heat drying time is 2 hours.

After two and a half hours, it was gradually cooled, and when it reached 80 ° C or lower, it was taken out of the oven. A discharge orifice was formed by an excimer laser or the like on the grooved top plate that had been subjected to the liquid repellent treatment, and the discharge orifice was bonded to a substrate having a discharge pressure generating element.

[Comparative Example 1] The same grooved top plate as in Example 1 was molded and subjected to UV / O ₃ treatment for 10 minutes, and then an amine silane coupling agent or an epoxy silane coupling agent, preferably an amine silane cup. After dipping the ring agent in water or a solution diluted with water / ethanol aqueous solution of 5 to 0.05 wt% for 1 minute, the ring agent was washed twice in a large volume of pure water. Then, it was air-dried, and then, as in Example 1, the same absorber was used and applied to the grooved top plate in the same manner. As the liquid repellent treatment agent, Cytop CTX-805A (manufactured by Asahi Glass) or CTX-805E (manufactured by Asahi Glass) is used as CT-solv.
What was diluted with 100 (boiling point 100 degreeC Asahi Glass Co., Ltd.) to 0.5 wt% was used. The grooved top plate on which the coating was completed was placed in a tray and placed in an oven at 150 ° C. for 2 hours and a half, and was dried by heat. At this time, since the temperature of the grooved top plate and the tray is raised to a predetermined temperature of 150 ° C. for 30 minutes after charging, the actual heat drying time is 2 hours.

After 2 and a half hours, it was slowly cooled, and when it reached 80 ° C. or lower, it was taken out of the oven. A discharge orifice was formed by an excimer laser or the like on the grooved top plate that had been subjected to the liquid repellent treatment, and the discharge orifice was bonded to a substrate having a discharge pressure generating element.

Next, in order to investigate the liquid repellency performance of the ink jet recording head treated with the specific polymer of the present invention, the applicability to the substrate, the initial characteristics, the liquid repellency persistence, etc. were evaluated. The contents are shown below. [Evaluation content] (1) Coating performance on base material Applicability → Presence or absence of coating unevenness Adhesion with base material → Solvent cracking, peeling (groove or discharge element 60 ° C Stored in ink Check pressure cooker test (Check after 20 hours) (2) Initial characteristics Initial contact angle → contact angle (forward and backward) (3) Liquid repellency persistence Liquid repellency → Change in contact angle before and after test (receding contact angle is θ _R2 ) (60) ℃ ink immersion) Abrasion resistance → Change in contact angle before and after the test (receding contact angle is θ
_R2 ) (using a rubbing endurance tester, 150,000 times) PCT → Change in contact angle before and after the test (receding contact angle is θ _R2 ) (120 ° C, 2 atm, 20 hours after ink immersion check) Show.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

[0048]

[Table 5] As shown in Table 1, in Example 2, slight peeling occurred at the edge portion after 20 hours of PCT after one month immersion in 60 ° C. ink. The ink resistance was almost the same as the treatment in Examples 1 and 2 and Comparative Example 1.

Next, the measurement results of the contact angle of the initial characteristics in Table 2 are shown. The method of measuring the contact angle here will be described. The contact angle normally described in catalogs and the like is called the advancing contact angle. For measurement, after dropping ink as shown in FIG. 2, the stage is lowered and the angle of the separated droplet is read.

On the other hand, the receding contact angle was used in the water repellency evaluation of ink jet. In this method, the ink is dropped once as shown in FIG. 2, the ink is sucked after the ink is wetted, and the angle of the droplet left at that time is measured. Here, the receding contact angle θ _R1 and the receding contact angle θ _R2 were separately measured according to the amount of ink initially ejected. Conventional contact angle is θ
_This is indicated by _R1 . When θ _R1 and θ _R2 are compared, of course, θ _R2 is a stricter condition, so that a difference in water repellency is likely to occur, which is effective for evaluation.

As far as Table 2 is seen, there is almost no difference in the initial water repellency from each of the Examples and Comparative Examples. It also clears the uniform standard of θ _R2 ≧ 70 degrees on the surface of the inkjet head orifice.

Table 3 shows the change in contact angle before and after the 60 ° C. ink immersion test. In all cases, there is little decrease in θ _{R2 within} 1 month of immersion. Table 4 shows the change in contact angle before and after the rubbing test, and here also in both Examples 1 and 2 and Comparative Example 1, θ _R2
It satisfies ≧ 70 degrees. Particularly, in Examples 1 and 2, there is almost no decrease from the initial value. In the comparative example, minute scratches that cannot be confirmed by microscopic observation are generated and the contact angle is reduced. Table 5 shows the change in contact angle before and after PCT, but the test condition is the most severe, and the decrease in contact angle after 20 hours is the largest. Examples 1 and 2 and Comparative Example 1 are θ _R2
I was able to maintain ≧ 70 degrees. In summary, it was found that Examples 1 and 2 and Comparative Example 1 were excellent in water repellency persistence and mechanical durability. Particularly in Examples 1 and 2, it was possible to improve the mechanical durability and maintain the adhesiveness with the base material without subjecting the base material to a specific surface treatment.

The number of steps in Example 1 is simplified as compared with the comparative example, and is the most practical. When an ejection observation printing test was performed on the ink jet recording head that was subjected to the liquid repellent treatment of the present invention, ejection signals were applied at a frequency of 2 to 10 KHz, and stable ejection was always possible in a predetermined direction even when all nozzles were driven simultaneously. In addition, the printed matter was good without causing problems such as vertical line deviation and solid printing margins.

[Example 3] A bell eater (made by Kanebo) as an absorber was cut into a predetermined size, the absorber was dipped in a water repellent, and the pulled up product was pressed against the orifice surface of the grooved top plate. The coating was performed by moving it while moving. As the liquid repellent (thickness: 2 μm), a 5% solution of CYTOP CTX-805A (manufactured by Asahi Glass Co., Ltd.) was used. As a filler, Cefbon-CMA ((CF) _n , average particle size 2 μm) was added in an amount of 1.0 wt% with respect to the main resin. This was ultrasonically cleaned for 10 minutes to completely disperse it.

Put the grooved top plate on the tray,
It was put in an oven at 150 ° C. for 2 and a half hours and dried by heat. At this time, since the temperature of the grooved top plate and the tray is raised to a predetermined temperature of 150 ° C. for 30 minutes after charging, the actual heat drying time is 2 hours.

After two and a half hours, it was gradually cooled, and when it reached 80 ° C or lower, it was taken out of the oven. A discharge orifice was formed by an excimer laser or the like on the grooved top plate that had been subjected to the liquid repellent treatment, and the discharge orifice was bonded to a substrate having a discharge pressure generating element.

[Example 4] As in Example 3, the same absorber was used and the grooved top plate was coated in the same manner. (Film thickness 2 micron) As a liquid repellent treatment agent, Cytop CTX
A 5 wt% solution of -805A (manufactured by Asahi Glass Co., Ltd.) was used. As the insoluble resin, Cefbon-CMF ((CF)
_n , average particle size 0.1 micron) to the base resin 1.
0 wt% was added and dispersed in the same manner as in Example 3.

Put the grooved top plate on the tray,
It was put in an oven at 150 ° C. for 2 and a half hours and dried by heat. At this time, since the temperature of the grooved top plate and the tray is raised to a predetermined temperature of 150 ° C. for 30 minutes after charging, the actual heat drying time is 2 hours.

After two and a half hours, it was gradually cooled, and when it reached 80 ° C or lower, it was taken out of the oven. A discharge orifice was formed by an excimer laser or the like on the grooved top plate that had been subjected to the liquid repellent treatment, and the discharge orifice was bonded to a substrate having a discharge pressure generating element.

[Example 5] As in Example 3, the same absorber was used and the grooved top plate was coated by the same method. (Film thickness 2 micron) As a liquid repellent treatment agent, Cytop CTX
A 5 wt% solution of -805A (manufactured by Asahi Glass Co., Ltd.) was used. As the insoluble resin, Cefbon-CMF ((CF)
_n , average particle size 0.1 micron) to the base resin 1.
0 wt% was added and dispersed in the same manner as in Example 3.

The grooved top plate which has been applied is put in a tray,
It was put in an oven at 150 ° C. for 2 and a half hours and dried by heat. At this time, since the temperature of the grooved top plate and the tray is raised to a predetermined temperature of 180 ° C. for 30 minutes after charging, the actual heat drying time is 5 hours. After 5 and a half hours, it was slowly cooled, and when it became 80 degrees or less, it was taken out from the oven. A discharge orifice was formed by an excimer laser or the like on the grooved top plate that had been subjected to the liquid repellent treatment, and the discharge orifice was bonded to a substrate having a discharge pressure generating element.

[Comparative Example 2] The same grooved top plate as in Example 3 was molded and subjected to UV / O ₃ treatment for 10 minutes, and then an amine silane coupling agent or an epoxy silane coupling agent, preferably an amine silane cup. After dipping the ring agent in water or a solution diluted with water / ethanol aqueous solution of 5 to 0.05 wt% for 1 minute, the ring agent was washed twice in a large volume of pure water. Then, it was air-dried, and then, as in Example 3, the same absorber was used and applied to the grooved top plate by the same method. (Film thickness 2 microns) As a liquid repellent treatment agent, Cytop CTX-80
5A (made by Asahi Glass) was used. The grooved top plate on which the coating was completed was placed in a tray and placed in an oven at 150 ° C. for 2 hours and a half, and was dried by heat. At this time, since the temperature of the grooved top plate and the tray is raised to a predetermined temperature of 150 ° C. for 30 minutes after charging, the actual heat drying time is 2 hours.

After 2 and a half hours, the product was gradually cooled, and when it reached 80 ° C or lower, it was taken out of the oven. A discharge orifice was formed by an excimer laser or the like on the grooved top plate that had been subjected to the liquid repellent treatment, and the discharge orifice was bonded to a substrate having a discharge pressure generating element. Next, in order to investigate the liquid repellency performance of the inkjet recording head treated with the specific polymer of the present invention, applicability to a substrate, initial characteristics, liquid repellency persistence, etc. were evaluated. The evaluation contents are the same as those in Examples 1 and 2 and Comparative Example 1. The evaluation results are shown below.

[0064]

[Table 6]

[0065]

[Table 7]

[0066]

[Table 8]

[0067]

[Table 9]

[0068]

[Table 10] As shown in Table 6, in Example 3, slight peeling occurred after 20 hours of PCT after 1 month immersion in 60 ° C. ink. The ink resistance was almost the same as that of the treatment in Examples 4 and 5 and Comparative Example 2.

Next, the measurement results of the contact angle of the initial characteristics in Table 7 are shown. The method of measuring the contact angle here will be described. The contact angle normally described in catalogs and the like is called the advancing contact angle. For measurement, after dropping ink as shown in FIG. 2, the stage is lowered and the angle of the separated droplet is read.

On the other hand, the receding contact angle was used in the water repellency evaluation of ink jet. In this method, the ink is dropped once as shown in FIG. 2, the ink is sucked after the ink is wetted, and the angle of the droplet left at that time is measured. Here, the receding contact angle θ _R1 and the receding contact angle θ _R2 were separately measured according to the amount of ink initially ejected. Conventional contact angle is θ
_This is indicated by _R1 . When θ _R1 and θ _R2 are compared, of course, θ _R2 is a stricter condition, so that a difference in water repellency is likely to occur, which is effective for evaluation.

As far as Table 7 is concerned, regarding the initial water repellency, the advancing contact angle exceeds 100 ° C. in each Example and the water repellency is good. The receding contact angle is also θ on the orifice surface
_It exceeds the standard of _R2 ≧ 70 degrees.

Table 8 shows the change in contact angle before and after the 60 ° C. ink immersion test. In all cases, there is little decrease in θ _{R2 within} 1 month of immersion. Table 9 shows the change in contact angle before and after the rubbing test, and here also in both Examples 4 and 5 and Comparative Example 2, θ _R2
It satisfies ≧ 70 degrees. Particularly, in Examples 4 and 5, there is almost no decrease from the initial value. In Comparative Example 2, minute scratches that cannot be confirmed by microscopic observation are generated and the contact angle is reduced. Table 10 shows the change in contact angle before and after PCT, but the test condition is the most severe, and the decrease in contact angle after 20 hours is the largest. The decrease in the contact angle in Example 3 is considered to be the decrease in the adhesion to the substrate because the diameter of the filling particles was about the same as the film thickness. In Examples 4 and 5 and Comparative Example 2, θ _R2 ≧ 70 degrees could be maintained. In summary, it was found that Examples 4 and 5 and Comparative Example 2 were excellent in water repellency persistence and mechanical durability. In particular, in Example 5, the wettability could be improved only by increasing the heat treatment time. It is considered that this is because the density of perfluoro groups on the film surface increased due to the effect of the bleeding of the filler on the surface or the molecular rotation of the main agent. The number of steps in Example 5 is simplified as compared with the comparative example, and is practically the best. When an ejection observation printing test was performed on the ink jet recording head that was subjected to the liquid repellent treatment of the present invention, ejection signals were applied at a frequency of 2 to 10 KHz, and stable ejection was always possible in a predetermined direction even when all nozzles were driven simultaneously. In addition, the printed matter was good without causing problems such as vertical line deviation and solid printing margins.

[0073]

As described above, the compound of the present invention can form a semi-permanent liquid repellent treatment layer on the surface of an orifice by a treatment much easier than in the past, and always have a substantially uniform liquid amount in a predetermined direction. It is possible to form a head that can perform stable ejection and can be sufficiently applied to high-speed recording.

[Brief description of drawings]

FIG. 1 is a developed perspective view illustrating the configuration of a normal inkjet recording head.

FIG. 2 is an explanatory diagram showing a method for measuring a contact angle.

[Explanation of symbols]

 11 Base 12 Discharge Pressure Generating Element 13 Photosensitive Resin Cured Film 14 Orifice 15 Flow Path 16 Liquid Chamber 17 Top Plate 19 Adhesive 20 Liquid Repellent Treatment Layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08K 3/04 KJF C08L 27/12 LGH C09D 127/12 PFH

Claims (8)

[Claims] 1. A method for surface treatment of an ink jet recording head, which comprises applying a resin composition obtained by filling inorganic or organic fine particles in an amorphous thermoplastic resin having a perfluoro structure to the ink jet orifice surface. 2. The amorphous thermoplastic resin having a perfluoro structure is an amorphous thermoplastic resin having a perfluoro structure soluble in a specific perfluoro solvent in at least its molecule, and the inorganic fine particles are insoluble in a solvent. 2. The method for surface treatment of an inkjet recording head according to claim 1, wherein the surface treatment method is a fluorine-containing compound. 3. The amorphous thermoplastic resin having a perfluoro structure is an amorphous thermoplastic resin having a perfluoro structure soluble in a general organic solvent in at least its molecule, and the inorganic fine particles are insoluble in a solvent. 3. The method for surface treatment of an ink jet recording head according to claim 2, wherein the surface treatment method is a fluorine-containing compound. 4. A surface treatment method for an ink jet recording head, which comprises coating the ink jet recording orifice surface with the resin composition according to claim 1 or 2 by a casting method, a dipping method or a transfer method. 5. The method for surface treatment of an ink jet recording head, wherein the polymer compound containing a perfluoro structure according to claim 1 or 2 is an amorphous thermoplastic resin having a perfluoro heterocyclic structure. 6. The surface of the filled fine particles according to claim 1 is treated with an organic titanate or a silane coupling agent to control surface wettability to improve dispersion stability in a polymer solution and adhesion to an orifice material. Method for surface treatment of ink jet recording head. 7. A method for surface treatment of an ink jet recording head, wherein the solvent-insoluble fluorine-containing compound according to claim 2 or 3 is graphite fluoride. 8. A method for surface treatment of an ink jet recording head, wherein the silane coupling agent according to claim 5 contains at least one perfluoro group in its structure.