JP3772613B2 - Method for manufacturing nozzle plate for inkjet head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in processing accuracy of a nozzle plate for an inkjet head.
[0002]
[Prior art]
If ink droplets or dust adhere to the vicinity of the ejection nozzle of an inkjet head for an inkjet recording apparatus, the nozzle mouth becomes dirty, the direction of the ejected ink droplet bends, the ejection amount decreases, or it becomes impossible to eject, etc. Significantly reduce image resolution. Further, it is known that ink droplets cannot be ejected when the adhered ink covers the entire nozzle opening. In addition, when the nozzle surface is wet with ink, a medium, for example, fine fibers of paper or cloth, may adhere, and if it touches the nozzle opening, ejection may be hindered. The reason why the nozzle opening is soiled is that the pressure applied to the ink remains after ejection, causing the ink in the nozzle to vibrate, causing the ink to overflow from the nozzle opening, and the ink that collides with the medium to splatter into fine droplets. Bounces off, adheres to the nozzle surface, the tail of the ejected ink drop breaks, the generated satellite adheres, and the head suddenly accelerates or decelerates at the end of the operating range of the carriage on which the head is mounted For this reason, it is considered that a large change in acceleration occurs and ink overflows from the nozzle opening due to inertial force.
[0003]
In particular, if ink that overflows from the nozzle orifice due to residual vibration or inertia force adheres unevenly on the circumference of the nozzle orifice, the ink droplets are bent and the image is severely deteriorated. Ink repellent treatment prevents the ink from overflowing from the nozzle opening, or the overflowed ink is repelled on the ink repellent surface to form fine droplets. It is desirable that ink droplet ejection is not hindered.
[0004]
Ink and dust adhering to the nozzle mouth surface gradually accumulate and grow into large ink droplets, and then come into contact with the nozzle mouth, so sometimes the ejection is stopped, the head is moved to the service station, the sponge and A cleaning process is performed in which the head surface is wiped with a porous material such as a rubber blade to remove the adhered ink and dust. At this time, if the nozzle opening is damaged by wiping, dust adhesion and the like are further promoted.
[0005]
For this reason, ink repellent treatment has been performed so that ink does not adhere to the vicinity of the nozzle opening.
[0006]
Various methods have been proposed so far for applying an ink repellent treatment to the surface of the nozzle opening of an inkjet head. For example, JP-B-52-24821 and JP-A-56-21862 have coatings of materials having an ink-repelling property such as fluororesin and silicone resin. JP-A-57-72866, JP-A-60-255441, etc. Describes the use of tetrafluoroethylene / hexafluoropropylene copolymer (FEP) as the ink repellent film. This FEP has low surface energy (ink repellency) equivalent to that of polytetrafluoroethylene (PTFE), but its viscosity at the time of heating and melting is lower than that of PTFE. When forming a film, a uniform film can be obtained in a short time at a lower temperature than PTFE, and the film forming processability is excellent.
[0007]
On the other hand, as a nozzle hole processing method, for example, as disclosed in JP-A-6-87216, when a nozzle plate substrate is ablated by irradiation with an excimer laser, drilling using an excimer laser has been proposed. . This is relatively free from heat generation during laser processing, has features such as small damage other than the processed portion, and is excellent as a highly accurate processing method.
[0008]
[Problems to be solved by the invention]
Since FEP having excellent ink repellency does not absorb much in the vicinity of the wavelength of the excimer laser, ablation does not occur and workability by the excimer laser is not good. Therefore, when the FEP resin dispersion is applied to the nozzle plate base material and heat treatment is performed to form an ink repellent film and then nozzle processing is performed with an excimer laser, the base material is excellent in excimer laser processability. The processing accuracy deteriorates at the stage of processing the ink repellent film, and the vicinity of the discharge port that affects the discharge angle is affected by this, and the discharge characteristics cannot be obtained.
[0009]
The present invention has been made in view of the above circumstances, and an object of the present invention is to produce a nozzle plate having an FEP ink repellent film and having a high print quality in which nozzle holes are precisely processed using an excimer laser. It is to provide a method .
[0010]
[Means for Solving the Problems]
The above object of the present invention is to
A method of manufacturing a nozzle plate for an ink jet head having an ink-repellent film, the step of applying a dispersion of tetrafluoroethylene / hexafluoropropylene copolymer (FEP) to a nozzle plate substrate made of polyimide, and tetrafluoro a step of drilling the nozzle holes by the irradiation of an excimer laser pasted an adhesive sheet to an ethylene-hexafluoropropylene copolymer dispersion coating film, tetrafluoroethylene-hexafluoropropylene by heating after which the adhesive sheet peeled off by A method of manufacturing a nozzle plate for an ink jet head having a step of forming an ink-repellent film by melt-forming a propylene copolymer and the pressure-sensitive adhesive sheet is selected from natural rubber, polyisoprene rubber, styrene-butadiene rubber, and polyisobutylene Having an adhesive Excimer laser irradiation is performed from the side opposite to the surface coated with the dispersion liquid, and an adhesive sheet is bonded to the formed ink repellent film surface, and vacuum plasma treatment or from the side opposite to the surface is performed. Having a step of performing a cleaning process by a cleaning device equipped with an ultraviolet light source;
Achieved by:
[0011]
The present invention will be described in detail below.
The present invention employs, as a nozzle plate substrate, a FEP resin ink-repellent film having low excimer laser processability, which can be heat-treated at 300 to 400 ° C. at which the FEP resin melts, and has good processability by excimer laser. Nozzle holes are drilled before the melt film formation to solve the problem of workability.
[0012]
There is no suitable solvent for dissolving the FEP resin, but the aqueous dispersion of FEP contains FEP fine particles, surfactant, water and other additives as ingredients, and is manufactured by Daikin Industries, Ltd. ND-1 and DuPont. 120-J and the like are commercially available, and a coating solution may be prepared based on this.
[0013]
Since the film formed by applying the FEP dispersion is easily peeled off, an adhesive sheet is bonded to protect the film. The adhesive is a rubber-based material selected from natural rubber, polyisoprene rubber, styrene-butadiene rubber, and polyisobutylene. For the workability by excimer laser, the FEP dispersion is applied when the adhesive sheet is peeled off. It is also preferable because the surface of the formed film is maintained in a uniform state.
[0014]
Nozzle holes are formed by excimer laser irradiation, and then the pressure-sensitive adhesive sheet is peeled off and heat treated to prevent contamination of the surface of the ink repellent film, and the FEP resin is melted to form an ink repellent film.
[0015]
Since an uncured FEP resin dispersion coating film is processed, it is preferable to perform excimer laser processing from the side opposite to the coating film surface.
[0016]
Further, it is preferable to clean the nozzle plate by bonding an adhesive sheet to the formed ink repellent film surface and performing etching by vacuum plasma treatment or ultraviolet irradiation treatment from the opposite side of the surface.
[0017]
The vacuum plasma treatment is a cleaning treatment by generating a plasma state with a high frequency power source at a vacuum degree of about 133 to 0.133 Pa (1 to 0.001 torr) in an atmosphere of oxygen, nitrogen, carbon dioxide, argon or a mixed gas thereof. Is to do. Some cleaning devices equipped with an ultraviolet light source directly perform a cleaning process using short-wavelength ultraviolet light and perform an indirect cleaning process using ozone generated by ultraviolet light.
[0018]
The effect of the above-described washing treatment is advantageous in that the ink meniscus surface is stabilized at the nozzle plate end surface (tip portion) by making the nozzle inner wall surface hydrophobized by the heat treatment into an inphilic ink, and stable ink discharge is performed. Good.
[0019]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples described below.
[0020]
Example 1
A 75 μm thick polyimide sheet (Ube Industries, Upilex S) is used as the nozzle plate base material, and FEP aqueous dispersion (manufactured by Daikin Industries, Ltd., NEOFRON ND-1) is dried to 3 μm with a wire bar. It was applied in such a way that it was allowed to stand at room temperature and dried.
[0021]
Next, a Nichiban cellophane tape was applied to the dispersion coating film surface, and then a nozzle hole with a diameter of 25 μm was applied from the opposite side of the coating film surface with an excimer laser (wavelength 248 nm KrF laser, energy density 2.0 J / cm ² ). Processing was performed.
[0022]
The cellophane tape was peeled off in a static eliminator and heat treatment was performed at 350 ° C. for 1 hour in a baking furnace.
[0023]
After completion of the heat treatment, a cellophane tape is applied as a masking tape to the formed ink-repellent surface, and UV light is irradiated from the opposite side of the surface with a UV cleaner (manufactured by Kanko International Laboratories, UV-660) for cleaning. A nozzle plate was prepared.
[0024]
On the other hand, a 75 μm-thick polyimide sheet (above) was used, and an aqueous FEP dispersion (same as above) was applied with a wire bar to a dry film thickness of 2 μm, left at room temperature, dried and then baked in a baking oven. Heat treatment was performed at 1 ° C. for 1 hour.
[0025]
Next, cellophane made by Nichiban Co., Ltd. was affixed to the dispersion coating film surface, and then nozzle holes were similarly processed with an excimer laser from the opposite side of the coating film surface to prepare a comparative nozzle plate.
[0026]
These nozzle plates were bonded to piezo-type actuators to produce inkjet heads, and the discharge angle variation was compared. That is, ten heads each having 64 nozzles were prepared, and the average of the standard deviation of the discharge angle variation was determined. The average value of the standard deviation of the discharge angle variation of the head according to the present invention was 0. .4 degrees, that of the comparative head was 1.3 degrees.
[0027]
The variation in the discharge angle is suppressed as the coating film thickness of the FEP dispersion is increased, but the present invention is effective even with a thin film of 0.1 to 1 μm.
[0028]
【The invention's effect】
According to the present invention, a nozzle plate for an inkjet head with high print quality can be easily produced with high processing accuracy.

Claims (4)

A method of manufacturing a nozzle plate for an ink jet head having an ink-repellent film, the step of applying a dispersion of a tetrafluoroethylene / hexafluoropropylene copolymer to a nozzle plate substrate made of polyimide, and a tetrafluoroethylene / hexa a step of drilling the nozzle holes by the irradiation of an excimer laser pasted an adhesive sheet hexafluoropropylene copolymer dispersion coating film, tetrafluoroethylene-hexafluoropropylene copolymerization by heating after which the adhesive sheet peeled off by method of manufacturing a nozzle plate for an inkjet head, characterized in that by melting deposited coalescing and forming an ink repellent layer. The method for producing a nozzle plate for an inkjet head according to claim 1, wherein the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive selected from natural rubber, polyisoprene rubber, styrene-butadiene rubber, and polyisobutylene. The method for producing a nozzle plate for an ink jet head according to claim 1 or 2, wherein the excimer laser irradiation is performed from the side opposite to the surface coated with the dispersion. Pasted an adhesive sheet formed ink repellent film surface, according to claim 1 which is the said surface characterized by having a step of carrying out cleaning with a cleaning apparatus provided with a vacuum plasma treatment or an ultraviolet light source from the opposite side 2. A method for producing a nozzle plate for an inkjet head according to 2 or 3.