JPH0764061B2 - INKJET HEAD AND METHOD OF MANUFACTURING THE SAME - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet head, and more particularly to an inkjet head capable of preventing wetting of nozzles by phase change ink and a method for manufacturing the same.

[Conventional technology]

BACKGROUND OF THE INVENTION Purifying images or documents onto paper or other print media with inkjet printers having one or more nozzles with one or more nozzles is becoming increasingly popular. An inkjet printer with multiple inkjet nozzles is used to form color images,
Each nozzle is supplied with a different color of ink.
These color inks are supplied onto the recording medium alone or in the form of a mixture to form a completed color print. Typically, all of the colors needed for printing are produced from cyan, magenta and yellow inks. In some cases, black ink may be added to the above mixed inks to print the material of the fabric and to perform faithful four-color printing.

In a normal arrangement, the recording medium is provided on a rotating drum, or goes through a mechanism such as a typewriter, and a printer head with an inkjet head placed on a moving table is moved in the axial direction of the drum. Do you exercise
Or, exercises that alternate with each other on the typewriter mechanism. As the head scans on the recording medium while drawing a spiral locus or moves alternately, the ink droplets are ejected from the minute external nozzles toward the printing medium, and the recording medium is ejected. An image is formed above. The ejection of the ink drops is synchronized with the rotating drum or typewriter mechanism by a suitable controller.

[Problems to be Solved by the Invention]

Various devices or methods are known for printing an image on a recording material with an ink based on an aqueous material. A significant problem when printing inkjet images with aqueous inks is the wetting of the ink ejection surface. Ink deposits on the ink ejection surface surrounding the nozzles ejecting the ink droplets result in non-uniform ink droplet size exiting the device, resulting in poor image quality. Therefore, methods have been provided to treat the ejection surface of an inkjet device with a non-wetting material to prevent the spread of ink deposits from the ink drop ejection nozzles of the inkjet device across the ejection surface. In U.S. Pat. No. 4,533,569, the inside surface of the glass nozzle is cleaned with hydrofluoric acid and covered with a protective material such as ethylene glycol, glycerin. After pretreatment with anions,
An anti-wetting agent, such as a long chain of anionic non-wetting materials, is applied to the fluid nozzle to enhance ink drop quality. U.S. Pat. No. 4,623,906 discloses a three-layer coating for glass or silicon inkjet nozzles containing silicon nitride or aluminum nitride. In U.S. Pat. No. 4343013, the nozzle plate of an inkjet printer is covered with a material made of glass and having non-wetting properties with respect to the aqueous properties of the ink components. Tetrafluoroethylene and certain silicon-based materials are useful for this purpose because they have the non-wetting properties already mentioned. In U.S. Pat. No. 4,368,476, a water repellent layer of silicon fluoride non-wetting material is provided on the surface surrounding the jet nozzle. In U.S. Pat. No. 4,643,948, the ink jetting nozzle plate is covered with a non-wetting coating containing partially fluorinated alkylsilanes and perfluorinated alkanes, respectively. In U.S. Pat. No. 4,728,393, the nozzle plate of an electrostatic deflection type inkjet printer is mirror-finished and completely covered with a thin film of Teflon resin. However, in this case, the Teflon coating is used for electrostatic control and not for ink drop formation. Ink drop formation is facilitated by the aid of air and mesa-shaped mechanism. For this reason, inkjet works without a Teflon coating. Other articles related to the wettability of fluorocarbon polymeric layers include IBM's Technical Disclosure Bulletin Vol. 26 by BD Washow entitled "Highly non-wettable surfaces from plasma polymer deposition of tetrafluoroethylene". No. 4, p. 2074, and AJ entitled "Wetting of Perfluorinated Carbon Polymer Layers: Effect of Roughness"
Includes the paper on page 1 of Volume 39 of the Journal of Polymer Science by G. Alan et al.

In another inkjet printing technology, instead of an ink based on an aqueous material of an inkjet device, a non-aqueous phase change ink (Phase Change Ink, for example, an ink that changes phase from solid to liquid by heating. Changeable ink) has been used. The phase change ink is solid at room temperature, but becomes liquid at the operating temperature of the inkjet so that the phase change ink can be ejected onto the recording medium to draw a predetermined pattern. The ejected ink forms a pattern on the recording medium. For water-based ink,
As described above, due to the wetting of the surface, there is a problem of nonuniformity of ejected ink drops, and the same problem occurs in the case of phase change ink. This problem can be solved both conceptually and in terms of implementation by making particular improvements to the structure of the inkjet nozzle. Some examples are mesas, ink lumps, squeezing tubes, and dissimilar lumps of liquid. However, with these configurations,
The cost required to make it can be higher than desired. This is especially the case when the spouts are in rows.

Therefore, with the ink component including the phase change ink component, a reproducible and uniform ink droplet is generated, and therefore, an image can be printed on a recording medium with desired characteristics without costing a large amount of ink jet nozzles. There is a demand for an inkjet head that can do so.

Therefore, an object of the present invention is to provide an inkjet head that can reduce the wettability of the ink in the vicinity of the nozzle and can generate ink droplets having a uniform shape with high frequency, and a manufacturing method thereof.

Another object of the present invention is to enhance ink drop addressing performance,
It is to improve image quality and image positioning accuracy.

Still another object of the present invention is to provide an inkjet head capable of reducing the number of inkjet heads mounted in a printer or improving a printing speed, and a manufacturing method thereof.

[Means for Solving the Problems]

The present invention meets the need for inkjet printer heads by using the phase change ink components to exhibit the desired properties of ink drop formation described above. By employing the method and apparatus of the present invention, important image printing characteristics can be achieved on the print medium without the costly reconfiguration of the inkjet nozzle design for phase change inks. More specifically, by using the method of the present invention and the ink jet print head of the present invention, the printed image produced by the phase change ink has a good quality because the ink droplets are well formed and the positions of deposition are accurate. Further, an excellent and clear image can be provided without dropping.

In an ink jet device based on a water-based material,
By reducing the wettability of the ejection surface of the inkjet head, the properties of the ink droplets can be improved. This is accomplished by coating these surfaces with a material that inherently exhibits a much lower surface energy than aqueous inks. If the surface energy of the coating material is low, the contact angle of the ink will be a relatively high value, well above the minimum angle required to suppress wettability at the ink ejection surface near the nozzle. Therefore, for inks based on water-based materials, the conditions for producing high quality ink drops can be easily achieved.

Applicants have found that there is a large surface energy difference between various coating materials and water-based inks, i.e. at least about
We recognize that the 20 dynes / cm difference was not originally present between these coating materials and phase change inks. Therefore, in the case of water-based inks, even coating materials that were able to significantly reduce the wetting of the ejection surface would not work as well in the case of phase change inks.

It has been found by the present application that the image described above can also be formed with a phase change ink component by using an inkjet head having some type of nozzle plate. The nozzle plate forms at least one discharge nozzle, which need not be specially devised. This is accomplished by raising the contact angle of the ink in the area surrounding the ejection nozzle to a predetermined level, thereby preventing wetting of the previously surrounding surface area by the phase change ink component. It The contact angle of the ink is increased by providing a film of a specific coating material on the emission surface of the inkjet head. According to the teachings of the present invention, when the ejection surface is coated, the droplets of each liquefied phase change ink component are of substantially uniform size and shape and can be ejected according to a predetermined pattern, and thus, It is possible to form a printed image whose position is accurately determined on the recording medium with substantially no deterioration in quality.

Thus, an improved inkjet printhead is provided by providing the above method of providing a layer of coating material in the surface area of the print jet head surrounding each of the above discharge nozzles. In this coated (nozzle) surrounding surface area, the contact angle with the phase change ink increases to at least about 50 ° at operating temperatures of at least about 70 ° C. The coating material has been treated in the surrounding area being coated and maintains a high contact angle with the ink in the area surrounding the nozzle. Thus, at operating temperature, upon prolonged exposure of the enclosed area to the ink components, the contact angle will be at least about 20% greater than the contact angle on the area enclosed by the untreated coating material. Grows. This substantially prevents wetting of the surrounding surface area by the ink components. By this method, the inkjet printhead can eject a plurality of the above-mentioned individual ink droplets by using the phase change ink to form a print image on the print medium, the position of which is accurately determined without deterioration. it can.

The above-mentioned or other objects, features and advantages of the present invention will become more apparent by the detailed description of the preferred embodiments with reference to the drawings.

〔Example〕

FIG. 1 shows a sectional view of an inkjet head of the present invention for printing with a phase change ink component on a print medium. The inkjet head (10) includes a body portion (12) having a single compartment ink chamber (14) disposed therein. The ink chamber (14) is closed by a plate (16) which is a wall of the ink chamber. The outer surface of the nozzle plate (16) serves as a discharge surface (18).
The outside of the nozzle (20) for ejecting ink droplets formed by the nozzle plate (16) forms an area surrounding the nozzle (20), and the nozzle passes from the ink chamber (14) to the outside of the inkjet head (10). ing. Even if the nozzle plate (16) can be provided with a single nozzle (20), a plurality of nozzles and associated ink chambers may be provided as appropriate. The ink chamber (14) is composed of a portion (22) and a portion (24), and although it is not necessary to do so, the cross section is generally circular. The part (24) is adjacent to the wall (16) and the outer nozzle (20) and is partitioned by the inner wall (26) of the main body part (12). The part (22) has a larger diameter than the part (24) and is partitioned by the inner wall (28). Portions (22) and (24) are symmetrical about axis (30) as shown, but this is not necessary.

The melted phase change ink has an inlet (3
It is introduced from 2), flows through the ink passage (34), and is filled in the ink (14) in the inkjet head (10). The end of the ink chamber opposite the outer nozzle (20) is closed by a flexible membrane (38) such as stainless steel. The piezoceramic disk (36) is covered with metal on both sides and is attached to the film (38) to form a form of a pressure pulse generating element. However, other forms using piezoelectric ceramics may be used. A pressure pulse is generated in the ink chamber (14) in response to the electric pulse applied to the piezoelectric disk. As a result, ink droplets are ejected from the nozzle (20). The ink drops travel toward the print medium, where they create the desired printed image.

The emission surface (18) of the nozzle plate (16) has a layer of coating material (50), which is also selectively applied to the area surrounding the nozzle (20) of the inkjet head, as in the nozzle. The ink of the phase change ink component released from (20) substantially prevents wetting the surface of the entrapped area.

By providing a surface coating layer (50), surface wetting is substantially reduced and the contact angle of the ink on the coating layer is substantially increased. Typically,
The contact angle is based on ASTM (American Society of Testing Materi
al: American Society for Testing and Materials) standard D72445. Further, the contact angle is typically at least about 70 ° C. operating temperature, preferably at least 100 ° C., most preferably at least 150 ° C. operating temperature of the phase change ink, relative to the phase change ink, the ambient area. Is substantially maintained on the extended and exposed portion. Thus, in relation to the coating layer (50), the contact angle of the ink component generated by employing the present invention is maintained at least 50 °, preferably at least 55 °, more preferably 60 °. Maintained. Coating material, this material, for a period of at least 24 hours
The coating material is evaluated by measuring the contact angle of the phase change ink after soaking (ie aging) in the phase change ink at a temperature of 150 ° C. The angle between a given phase change ink and the coating material is
It is measured with a bearing model No. 100-00-115 goniometer manufactured by Rame-Hart Inc.

To maximize the contact angle, the difference between the surface energy of the coating material and the surface tension energy of the phase change ink components must be minimized. To be more specific,
The surface energy of the coating material is at least about 4 dynes / c compared to the surface energy of the phase change ink component.
It is desirable that m, more preferably 6 dynes / cm lower.
The surface energy of the coating material and the surface tension energy of the phase change ink are preferably measured by a goniometer as described above.

The material commonly employed as the coating material (50) is a polymeric material, preferably a fluorocarbon polymer having the required ink contact angle and surface energy level as previously described. The fluorocarbon polymer selected is a polymer under the DuPont Teflon trademark, especially Teflon PTFE (polytetrafluoroethylene), and Teflon PFA (polyperfluoroalkoxy butadiene), or Teflon PTFE.
Or fluorocarbon dispersion, which is a dispersion of either Teflon PFA. A suitable dispersion is the Teflon PT described above in the product "Dynaplate" of Richardson Industry Co., Model 75-A and Model 75-R.
It is a colloidal fluorocarbon polymer dispersed in electroless nickel, such as one in which FE is dispersed.

Inkjet head (10) coating material (50)
There are various ways to apply. These methods include thermal vapor deposition, dipping of fluorocarbon polymers, followed by spin coating or spin coating of an aqueous fluorocarbon dispersion with subsequent thermosetting treatment.
g), deposition of fluoropolymer on the substrate by plasma polymerization of precursor monomers, and deposition with colloidal fluorocarbon in electroless nickel. Preferred methods are thermal vapor deposition of fluorocarbon resins and deposition of colloidal fluorocarbons in electroless nickel.

The coating layer (5
To keep the surface energy of 0) even better, the polymeric material is annealed by heating following deposition. This controlled heating often takes the form of a thermal cycle, where the coating layer (50) undergoes individual heat treatment steps at individual annealing temperatures to complete this step. The preferred annealing temperature in each heat treatment step is about 150 ° C to 500 ° C, more preferably 200 ° C to 400 ° C.

Most phase change ink components can be employed as part of the essence of the invention, however, suitable phase change ink components are those that are effective at the elevated operating temperatures described above. By way of example, the phase change ink component includes a phase change ink carrier component, preferably a resin material containing a fatty amide with a tackifier, a plasticizer and a colorant. A preferred fatty amide resin material is a combination of a tetraamide mixture and stearyl stearamide.

<Regarding Head Configuration> Here, a phase change inkjet printer head of the present invention is shown that includes a nozzle plate covered with a layer of coating material. This also provides the method of the present invention for producing an accurate printed image at locations with substantially no degradation with the phase change ink component. The subject coated device is compared to a similar printer head with an uncoated nozzle plate.

As described above, the experiment was performed with the jet printer head as shown in FIG. 1 in the case where the coating layer (50) of Teflon PFA (polyperfluoroalkoxy butadiene) was used as described in <Method of forming coating layer>. In some cases, ink drops of phase change ink have been made. The jet heads are both of the same construction and have a chemically corroded stainless steel layer structure integrally attached to the monolithic unit.

Jetting is characterized by the point in the ink drop formation process and the maximum number of ink droplets ejected per second when jetting failure occurs. This characteristic is that the image pickup device extends from the ink opening to a position on the axis about 1 mm downstream from this opening.
Observed using electrical delay circuits and strobe lights. This image pickup device is composed of a microscope provided perpendicularly to the trajectory of the ink droplet. The microscope is connected to a video camera, which is connected to a monitor. The magnification of the device was about 250 times. Strobe lights illuminate ink drops. The device is controlled by a delay circuit which is triggered by a drive signal leading to the injection. This delay circuit made it possible to measure the temporary ink drop formation process.

As the ink component of the fatty amide, the following components were used. Union Camp Tetraamide 39.2%, Steryl Stearamide 49.0%, Herculs Inc. Tackifier Foral 105 9.8%, and Monsanto Campani (Monsa).
2% plasticizer sanity sizer 278 manufactured by Nto Company. The operating temperature during each injection was set to 160 ° C. Union Camp Tetraamide is made by combining 1 mole of diacid, 2 moles of ethylene diamine, 2 moles of stearic acid. Because the surface is coated and annealed, the contact angle should be at least 60 when the ink and surface are heated to 150 ° C.
℃. When the surface is uncoated, the contact angle is at most 20 ° at 150 ° C.

The voltage of each jet is set so that when each jet produces 1000 drops per second, each drop reaches 1 mm downstream of the nozzle in 350 microseconds. A distance of 1 mm was chosen because it gives a good indication of how far the printer device is from the jet nozzle to the print medium. As the injection frequency increases,
The time required for the ink droplet to travel 1 mm, and the change in each ink droplet size and shape are recorded.

FIG. 3 compares the performance of the two injectors. This graph shows that an ejector with uncoated nozzles cannot generate as many drops per second as an ejector with a nozzle with such a coating. There is. When trying to produce 2000 drops per second, for uncoated jetting devices,
It becomes impossible to drive due to meniscus wetting around the nozzle. 10% per second for coated sprayers
It can be driven even when ejecting 000 or more ink drops. In either case, a single ink drop is formed at each generation frequency to the point where the ejection device cannot be driven.

The maximum drop generation frequency that the ejector can drive directly impacts the print engine architecture. The time required for a printer to produce a printed image is directly related to the number of ejectors available for printing, as well as the maximum number of drops produced per second from each ejector. The data can be said that, given a given copy time, an uncoated jetting device printer requires five times as many jetting devices as a coated jetting device printer. Otherwise, the former printer will take about five times as long as the latter printer.

The difference between the absolute maximum and absolute minimum (which defines the range) of the time required for a drop to travel 1 mm, as a function of repetition rate, also affects the print engine architecture. This range as a function of repetition rate has a direct bound on the positioning error of some drops. This error is the maximum addressability that an ejector can apply to printing (which is defined as the number of dots placed per inch, which is a more theoretical bitmap on the medium than physical dot placement. Related to placement.) The maximum addressability in the printing direction can be expressed as follows from the relationship with the change in the time until the ink droplet reaches the medium.

nD = 1 / (VΔt) Here, n is a positive number that determines the allowable range of the position of the ink droplet, D is the number of dots per inch, and V is the medium when the ink droplet is ejected. And the relative velocity of the ejector, and Δt, is the range of time to reach the print medium at its repetition rate as the ejector is printing. A typical value for n is 3, where 1/3 of the dot placement is the maximum amount of placement error that can be tolerated.
If, for example, the error is larger than this value, the information carried by these dots will not make sense on the medium, even if the same number of dots could be placed in one inch. Therefore, the maximum addressability that can make sense is low. From this equation, given n and V, the addressability decreases as Δt increases. If the addressability is constant, the relative speed can be reduced to compensate for the increase in Δt. A lower V will increase the printing time unless more jets are added to keep the printing level constant.

As can be seen from FIG. 3, the time required for the ink droplet to travel 1 mm increases rapidly in the case of the uncoated ejector until the ejector cannot be driven. The range of Δt for this uncoated injector was about 120 microseconds. For coated injectors, the Δt range was only 25 microseconds. Therefore, the presence of the coating improves Δt to about 1/5. From this discussion, this 1/5 difference in Δt means that, given n and V, the addressability of a coated injector is five times that of an uninjected injector. I understand that Otherwise, it can be said that the printing time of a coated jet is 1/5 of the printing time of an uncoated jet. Similarly, to achieve similar print times and addressability as for uncoated jetting devices,
It can be said that the number of coated injectors is 1/5.

<Method of forming coating layer> In this example, a suitable method of applying the coating material of the present invention is shown. There are several electron beam evaporation devices on the market for applying coating layers that are similar to ours. One such device is the CHA Industry Electron Beam Evaporator, Model # SE600. FIG. 2 is a perspective view of the electron beam evaporation apparatus, but as shown in FIG. 2, the coating material is applied to the cutting test piece (70). This sample is made of stainless steel of the type used when making inkjet heads. The electron beam evaporator (60) has a bell-shaped lid (62) and a base plate (64).
A vacuum deposition chamber (66) supported by and sealed by these is formed. The source of this polymeric coating material is Teflon PF in a metal retention cup (72).
It is polyperfluoroalkoxy butadiene which is the rod (68) of A. The vapor deposition chamber (66) is evacuated by a pump (not shown) communicating with the vapor deposition chamber (66). Sample holder (74)
Is attached to the top of the bell-shaped lid (62). The coupon (70) is placed on the sample holder (74) just above the rod (68). The electron beam source (76) is located directly below the holding cup (72).

The vacuum deposition chamber (66) is evacuated to an initial pressure of about 5X10 ^-6 Torr and has a pressure of about 5X10 ^-4 Torr during evaporation. The power of the electron beam is maintained at about 300 watts during driving. The coupon is heated to approximately 120 ° C. by an infrared lamp (78) located above the coupon in a bell-shaped lid. Even though the electron beam source is below the pedestal, the beam is generated at an angle, is deflected by the magnetic field, is directed into the pedestal, and is focused. Polymeric rod (68) is 300 ℃ -600 ℃ by electron beam source (76)
To be heated during. The electron beam vaporizes the polytetrafluoroethylene material, the vapor of which is concentrated on it to coat the coupon.
A coating layer with a thickness of about 400 nm to 600 nm is produced by the method.

The coated sample was annealed under a nitrogen atmosphere in a belt furnace for about 1.75 hours during the entire process.
Perform sequentially. This belt-type furnace is divided into five temperature regions having substantially the same dimensions. In this, the belt moves at a constant speed, and the sample passes through each temperature region sequentially for the same time. The temperature of each area may be the same as or different from that of the adjacent area. In this example, the processing cycle is in the order of temperature of 200 ° C. → 400 ° C. → 400 ° C. → 400 ° C. → 200 ° C.

The effect of surface coating on the ink ejection surface surrounding the phase change inkjet nozzle is the effect of the coated and uncoated coupons made of stainless steel of the type used to make inkjet heads. It can be known by comparing the wettability with and. One was PFA coated and the other two uncoated samples had the following wettability:

a. The contact angle of the phase change ink on the annealed coating surface, measured at 150 ° C, before aging,
It was measured at about 68 °.

The surface tension of the phase change ink at 150 ° C was about 24.5 dynes / cm. The energy of the unaged coated surface was measured to be 16 dynes / cm. The contact angle of the phase change ink of the uncoated sample was only about 20 ° when measured under similar conditions.

b. After aging the samples by soaking them in ink at 150 ° C for 72 hours, the contact angle of the coated and annealed surface was measured to be about 60 ° at a temperature of 150 ° C. . The surface tension of the phase change ink at 150 ° C was also measured to be about 24.5 dynes / cm.
The energy of the aged coating surface was measured to be about 20 dynes / cm. The contact angle of the uncoated sample after aging was measured under the same conditions and was about 15 °.

c. As described in <Coating layer formation method>, the sample coated with Teflon PFA was tested at 150 ℃.
Aging was done by soaking in ink for 72 hours. These coated samples have not been annealed prior to aging. The contact angle of the phase change ink on these samples was measured to be about 72 ° before aging and 40 ° to 43 ° after aging.

Thus, the treated (annealed) and aged fluorocarbon polymer maintains a high contact angle with prolonged exposure to phase change inks at operating temperatures, and has a higher quality than untreated ones. It has been found that it is possible to position a printed image of the type already mentioned more accurately, without the loss of power.

<Others><Method of forming coating layer> was repeated using a coating layer by dispersion of an ofluorocarbon polymer, in this case a mixture by dispersion of polymer in nickel.

In this experiment, a commercially available electroless nickel mixture was utilized in the Richardson Industries Dynaplate formulation. Despite the fact that most of these formulations are nickel phosphate based, a boron nickel mixture is used therein. Richardson
A coating material containing 150 ml / liter of Industriz 752A, 50 ml / liter of Richardson Industriz 752A, and 800 ml of distilled water mixed with 30 submicro PTFE emulsion of DuPont. Used as.

A stainless steel coupon is soaked in the coating mixture described above at a temperature of 85 ° C to 90 ° C for 10 minutes to 30 minutes to form 0.00254 mm (0.0001 inch) to 0.0102 mm (0.001 mm).
004 inches) thick coating layer is formed. The sample is then annealed at a temperature of 300 ° C. for 1 hour in a nitrogen atmosphere.

The contact angle of the ink on the sample is 60 before aging.
After aging it was 58 °. This aging was performed by the same method as in <Method of forming coating layer>.

Thus, the inkjet heads coated with other treatments, the aged or unaged fluorocarbon polymers, and especially the fluorocarbon polymeric dispersions described above, can produce the required contact angle. Furthermore, it has therefore been found that even with phase change inks, it is possible in the previously described formats to print with precisely positioned images without quality degradation.

〔The invention's effect〕

In the present invention, the coating layer formed of the wetting reducing material and subjected to the annealing treatment is provided around the nozzle on the surface of the inkjet head. The surface energy of the coating layer is at least 4 dynes / cm less than the surface tension of the phase change ink even at an operating temperature of the inkjet head of at least about 70 degrees Celsius. This allows the phase change ink to form a contact angle with the coating layer of at least about 50 degrees even after the coating layer has been exposed to the phase change ink for a long period of time, as can be seen from the results of the aging experiment described above. Therefore, it is possible to generate ink droplets having a uniform shape with high frequency, and the addressability of the ink droplets is increased. Therefore, the image positioning is accurate without deteriorating the print quality. Further, it is possible to reduce the number of inkjet heads mounted on the printer and to improve the printing speed.

[Brief description of drawings]

1 is a sectional view of an ink jet head of the present invention, FIG. 2 is a perspective view of an apparatus for applying a coating layer to the material of the head of FIG. 1, and FIG. 3 is provided with a coating layer. 6 is a graph for comparing the ink jetting states of an inkjet head and an inkjet head not provided with a coating layer. In these figures, (10) is an inkjet head,
(20) is a nozzle and (50) is a coating layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ted E. Deua U.S.A. Oregon 97229 Portland Northwest Saltsman Road No. 77 670 (72) Inventor Donald Earl Citterington United States Oregon 97062 Chuarachin Southwest Siletz Do Live 10185 (72) Inventor Curtis F. Shelley Oregon, USA 97330 Coballis Northwest Roosevelt Drive 3415 (56) Reference JP 63-122559 (JP, A) JP 61-74849 (JP, A) ) JP-A-63-126757 (JP, A) JP-A-60-183161 (JP, A)

Claims (2)

[Claims] 1. An ink jet head for forming an accurate image on a print medium substantially without deterioration by ejecting ink droplets of a phase change ink from a nozzle, the ink jet head having a surface around the nozzle. With a coating layer formed of a wetting reducing material and annealed, the surface energy of the coating layer is at least 4 dynes above the surface tension of the phase change ink, even at operating temperatures of the inkjet head of at least about 70 ° C. / c
An inkjet head characterized in that the phase change ink has a small contact angle with the coating layer of at least about 50 degrees even after being exposed to the phase change ink for a long time. 2. A method of manufacturing an ink jet head, wherein an accurate image is formed on a print medium without substantially deteriorating by ejecting ink droplets of phase change ink from the nozzle, wherein the nozzle on the surface of the ink jet head. A coating layer formed of a wetting reducing material on the periphery of the coating layer, the coating layer is annealed, and the surface energy of the coating layer is controlled by the annealing treatment even at an operating temperature of the inkjet head of at least about 70 ° C. A method for manufacturing an inkjet head, characterized in that it can be kept at least 4 dyne / cm smaller than the surface tension of the changing ink.