JPH1086372A - Thermal ink jet print head having ink-resistant heat sink coat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a heat sink from the corrosive effect of ink by mounting a print head on the heat sink including a metallic base plate on which coats of a polymer material are built up in an electrophoretic manner and which has at least partly electrical conductivity. SOLUTION: A print head 10 includes a channel plate 11 which is aligned with and adheres to a heater plate 12 and which is anisotropically etched. This print head 10 is allowed to adhere to a heat sink 35 having a zinc base plate 32 coated with polymer coats 34 built up on both the surfaces thereof. In this case, polyether sulfone coats built up in an electrophoretic manner are formed on the zinc base plate 32. Further, the polymer coats 34 are formed after a dicing step of dividing the individual print head 10. Accordingly, insulating layers 18 of a thick film made of a photosensitive polyimide, which are inserted between the heater plate 12 and the channel plate 11, are protected by the polymer coats 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printing apparatus that uses energy to eject ink droplets contained in a channel formed inside a print head from an orifice onto a recording material. In particular, the present invention relates to an ink jet print head having an improved function of protecting the corrosive action of high pH ink on the heat sink portion of the print head.

[0002]

BACKGROUND OF THE INVENTION In ink jet printing technology, a printhead includes one or more ink-filled channels in communication with an ink supply chamber, the channels having one end formed as a nozzle orifice. The ink forms a meniscus at the nozzle before being ejected. Energy is applied to the ink channel in the form of heat generated by the pulsed driving of a heating resistor or by the force applied piezoelectrically to the walls of the channel, causing the ink droplets from the nozzles onto the recording material. Discharged. After the droplet has been ejected, ink is replenished to the channel, reforming the meniscus.

[0003] Ink, whether a resistor heater element in a thermal ink jet printer or a piezoelectric plate in a piezo printer, must flow in sufficient contact so that the energy generator can transfer energy to the ink. The ink used (typically pH 8
Due to the corrosive nature of the above, the ink-sensitive parts of the printhead must be protected with a protective coating.

[0004] Another area of the printhead that is susceptible to the corrosive effects of high pH inks is the heat sink used to attach the die of the thermal ink jet printer. The heat sink is typically made of a thermally conductive metal, such as zinc, coated with another metal that readily adheres to the printhead die, with nickel being the typical heat sink coating. A problem with coated metals is that they are complexed with any substance that has a free electron pair.
Water, ammonia, amino groups, imino groups, hydroxyl groups, or thiol groups are examples of complexing agents with free electron pairs.
Thus, inks having one or more components containing such groups can easily attack the nickel layer in contact with the heat sink. This always occurs during normal printing operations.
As a result, the heat sink corrodes over time.
Apart from impairing the appearance of the heat sink, a more serious aspect of such corrosion is the potential for detachment of the die from the substrate.

Another potential source of corrosion is the electrolytic reaction between nickel and zinc in the presence of moisture.

US Pat. No. 4,391,933 (Scala et al.) Discloses about 8 to about 20 percent of a solvent and about 0.5 to 5 percent of an epoxy resin dissolved in the solvent to form a discontinuous phase. About 75 to about 90% of a precipitant as a continuous phase, and an emulsifier in an amount sufficient to cause a stoichiometric excess of about 900% to react stoichiometrically with the epoxy and hydroxyl groups on the epoxy resin. An emulsion comprising: The conductive working piece is placed in the emulsion about 1/2 to 2 inches from the electrode immersed in the emulsion. A direct current potential is applied between the working piece and the electrode with the working piece as the anode. Until the desired thickness of coating is deposited on the working piece
At about 50 to about 400 volts, about 2 to about 50 milliamps are used. The solvent and the precipitant are preferably cyclohexanone and a ketone such as methyl ethyl ketone or isobutyl ketone, respectively. The epoxy resin is preferably a bisphenol A epoxy resin having an average molecular weight of about 2,000 to about 15,000. The emulsifier is preferably an amine.

US Pat. No. 4,642,170 discloses a method for electrophoretically depositing a coating of polysulfone or polyethersulfone on a conductive substrate. A solution containing no amine is formed in an organic solvent of polysulfone or polyethersulfone. An emulsion is formed by combining the solution with an organic insoluble in a polymer containing up to about 0.6 parts by weight of organic nitrogen per part by weight of polymer. A direct current is applied between the conductive substrate and the emulsion that results in the deposition of the polymer on the substrate. The disclosure of this patent is incorporated herein by reference.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet printing apparatus for forming an ink resistant coating on a printhead heat sink to protect the heat sink from the corrosive effects of the ink.

[0009] Another object of the invention is to provide a protective layer that is inert to chemical attack by ionic and molecular components in the ink.

A further object is to form an ink resistant coating having good adhesion properties on a metal heat sink.

Another object is to extend the pH range usable for thermal ink jet printheads.

[0012]

SUMMARY OF THE INVENTION These and other objects are to provide:
This is achieved by forming an electrophoretically deposited organic layer on a metal heat sink. In one example, a colloidal emulsion containing polyethersulfone was formed. Soak the zinc heat sink surface in the solution,
With an electric field applied, a thin layer of polyethersulfone is electrodeposited on the zinc surface to form a highly ink resistant adherent coating. In another example, a colloidal emulsion of epoxy resin is formed, and a thin layer of epoxy resin is electrophoretically coated on a zinc heat sink surface to form a high ink resistant adhesive coating. In another embodiment, a thermally conductive filler is added to the colloidal emulsion to form a coating with increased thermal conductivity.

[0013] In a further embodiment, a coating of polyarylene ether ketone is formed.

In a further embodiment, a coating of cross-linked polyarylene ether ketone and cross-linked polyether sulfone is formed to make the device more resistant to ink.

More particularly, the present invention relates to a thermal ink jet printer for discharging a recording liquid onto a recording medium, comprising: a print head including at least one channel for holding the recording liquid; The printing method, comprising: at least one nozzle for discharging the recording liquid onto a medium; and heater means for selectively heating the ink in the channel to discharge the ink in the channel from the nozzle. A head is mounted on a heat sink that includes an at least partially conductive metal substrate having a coating of a polymeric material electrophoretically deposited thereon.

The present invention also relates to a printing system in which a thermal ink jet print head discharges a recording liquid onto a recording medium, the print head comprising at least one chamber for holding the recording liquid, and a recording medium. At least one nozzle for discharging liquid onto a medium, channel means for providing a liquid flow path between the chamber and the nozzle, and energy generation for introducing energy to the liquid contained in the channel Means,
Means for selectively energizing the energy generating means for periodically discharging the liquid through the nozzles on the recording medium, wherein the printing system comprises: At least partially conductive heat sink substrate for transferring heat away from the print head, wherein the substrate has a thin polymeric material coated on the deposited surface.

[0017]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to U.S. Pat. No. Re. 32,572 to Hawkins et al., U.S. Pat. No. 5,010,355 to Hawkins et al., And U.S. Pat. 371 and a thermal ink jet printer of the type disclosed in U.S. Pat. No. 5,297,336 to Barolla, the disclosures of which are incorporated herein by reference in their entirety. It will be appreciated that the invention is useful in other types of printhead configurations, as will be shown below. As disclosed in these patents, thermal inkjet printheads align and bond anisotropically etched channel wafers to heater wafers and then apply the attached wafers to individual printheads. It is manufactured through a dicing process for separating. The printhead is then glued to a heatsink, which is likewise glued to a daughter board that makes electrical connections to the printhead. FIG. 1 shows a cross-sectional view of a printhead having a heat sink protected by an ink-resistant coating according to the principles of the present invention. The print head 10 includes a heater plate 12
Anisotropically etched channel plate 11 aligned and attached to the substrate. The print head is attached to a heat sink 35 having a zinc substrate 32 coated with a polymer coating 34 deposited on both surfaces in the manner described in the following examples. Further, a daughter board 20 having electrode wire bonds 13 for connection to a drive circuit and a power supply (not shown)
Is mounted on the heat sink 35. The channel plate 11 has a through-etched reservoir 14 with an open end serving as an inlet 15 and a plurality of anisotropically etched channels 16. The end of the channel 16 opens through the nozzle face 29 and ends at the inclined end 21. The open end of the channel is
Act as The heater plate comprises an array of heating elements 25 and a heater plate 1 facing the channel plate.
2 has an address electrode 22 formed on the surface thereof. The heating elements and electrodes are formed on the insulating layer 27 and are passivated by another insulating layer 28. In the preferred embodiment, the thick film insulation layer 18 is a 10 micron thick photosensitive polyimide interposed between the heater plate and the channel plate. Layer 18 is patterned and cured to expose the heating elements, thereby placing them in separate pits 26 and providing ink flow bypass pit 2 between reservoir 14 and ink channel 16.
4 is formed. Layer 18 is also patterned to expose electrode attachment terminals 31. Following the patterning step, layer 18 is cured. Thus, ink flows from the reservoir 14 toward the channel 16 around the closed end of the channel 21, as indicated by the arrow 23. The terminal 31 is connected to the daughter board electrode 13 by a wire bond 30. The anisotropically etched channel 16 has a triangular cross-sectional area, and the material surrounding the nozzle at the nozzle face 29 comprises silicon on the two sides of the triangular nozzle and a thick film layer on the third side. Material layer.

In the normal printing mode, the ink contacts the heat sink 32, but without protection, the heat sink 32 is subject to the corrosive action of the ink. However, in accordance with the present invention, layer 18 has an ink resistant coating 34
Protected. The coating 34 is formed after a dicing step that separates the individual print heads. The ink contacts the heat sink in several ways. (1) Since the heat sink and the front surface of the print head are so close, during printing, the ink flows continuously on the heat sink by capillary action. (2) In the maintenance mode, the wiper blade passes over the front of the print head and removes excess ink, so that the removed ink spreads over the front of the heat sink and becomes a hydrophilic liquid pool. (3)
It contacts the heat sink via an ink passage through the heat sink used for channel ink replenishment.

A specific embodiment of the present invention will now be described in detail. These examples are for illustration, and the invention is not limited to the materials, conditions, or processing parameters set forth in these examples.

[0020]

【Example】

Example I After dicing the deposited channels and heater wafers into individual printheads, the printheads are deposited on a heat sink with the inventive ink protective coating. In a first embodiment, an electrophoretically deposited 8 micron thick polyethersulfone coating 34 was formed on a 0.25 inch thick zinc substrate 32. For this particular embodiment, see Polyethersulfone (Amoco, Boundbrook, NJ, Victrex 30).
0P, 5.68 grams) was dissolved in 120 mL of N-methylpyrrolidone (NMP). This non-conductive solution was then rapidly added to about 706 mL of acetone in a stainless steel beaker acting as a cathode and magnetically stirred. Victrex 300P with NMP is only slightly soluble in acetone. The result was a cloudy colloidal emulsion consisting of negatively charged micelles. The colloidal particles had a diameter of about 1270 ° and each particle had a charge of about 39 esu. The average electrophoretic mobility of these particles is 8.2 × 10 −5 cm /
And the zeta potential of the particles is -2.
It was of the order of 1.3 mV. These emulsions contain 7
It was stable for about a day. The micelles in the colloidal dispersion described above contained a very large proportion (often as much as 50%) of NMP as part of the structure.

The negatively charged micelles migrate and deposit on the anode (substrate 32) under the influence of an applied electric field of about 50 volts. The thickness of the coating was controlled by measuring the amount of Coulomb passing under the applied electric field, resulting in a strictly uniform coating having a thickness of 8 to 9 microns. The substrate was then pulled out of the bath and air-dried for a time sufficient for the acetone to evaporate. Thereafter, the substrate was gradually heated in a 150 ° C. oven for 16 hours to fully cure the coating. Thereafter, the heat sink was immersed in the ink and left in a furnace at 50 ° C. for a long time. The heater was then pulled out of the ink reservoir periodically, washed with running deionized water to remove the ink from the parts, and then carefully examined under a microscope for evidence of erosion on the coating by the ink. Polyethersulfone coating 34 (Victrex
300P) with 7.5 weight percent of BASF B
Asacid Black X-34 dye, tested at 50 ° C for 10 days in an alkaline ink containing 10.5 weight percent sulfolane, 15 weight percent imidazole, 1 weight percent imidazole hydrochloride, and 66 weight percent water. did. After this firing period, the coating was not affected by the ink at all.
The print head 10 was then adhered to the heat sink 30 with an epoxy resin doped with silicone rubber, and the daughter board was mounted on the heat sink surface in a conventional manner.

Example II In another embodiment, the dispersion was formed with a thermally conductive filler, in particular, 1 to 50% by weight of carbon black and 10% by weight of Regal 330 were used. A 3 to 10 micron thick polyethersulfone layer
Formed on layer 34. This layer was more completely conductive than the layer formed in Example I, increasing the efficiency of the heat sink. A thermally conductive filler such as diamond powder or mica powder may be used instead of carbon black. The use of metal oxides, such as iron and copper oxides, was excluded because they were eroded by alkaline inks.

The advantage of covering the heat sink with an ink-resistant coating is not limited to the above-described structure.
It is equally useful in any printhead that utilizes a heat sink that is at least partially made of metal to protect the heat sink from the effects of ink corrosion.

EXAMPLE III After dicing the deposited channels and heater wafers into individual printheads, the printheads are applied to a heat sink having the ink protective coating of the present invention. Electrodeposited electrophoretically on 32 of a 0.25 inch thick zinc substrate. A 0.5 mil thick polyamide-imide coating 34 was formed. For example, U.S. Patent Nos. 4,533,448 and 4,425, the contents of which are incorporated herein by reference.
It is generally known to electrophoretically deposit a polymer coating on a conductive substrate, as disclosed in U.S. Pat. No. 4,467,467 and 4,425,474. In this particular embodiment, N-methylpyrrolidinone (Amoco,
A1-830, 11.24 grams) of a 33% solids polyamide-imide solution in 76.43 grams of N-methylpyrrolidinone, then acetonitrile (286) in a stainless steel beaker acting as a cathode.
G) and magnetically stirred. A colloidal emulsion formed. The zinc heat sink was immersed in the emulsion and then positively charged (as an anode) by applying an electric field of 25 volts for 10 seconds, resulting in coating of the resin film. After air drying, the heat sink coated with polyamide-imide was placed in a furnace at 50 ° C. for 15 minutes, at 100 ° C. for 15 minutes,
15 minutes at 0 ° C., 15 minutes at 200 ° C., 15 minutes at 250 ° C.
Heated for 0.5 minutes to cure the 0.5 mil thick film. Then, immerse the heat sink in the ink for 50 hours.
It was left in a furnace at ℃. The heater was then periodically withdrawn from the ink reservoir and washed in a free stream of deionized water to remove the ink from the parts, and then carefully examined under a microscope for evidence of erosion on the coating by the ink. The polyamide-imide coating 34 was thus tested in an ink of the type described in Example I at 50 ° C. for 10 days. After this period, the coating had not been affected by the ink at all. The print head 10 was then attached to the heat sink 30 using silicone rubber-doped epoxy and the daughter board was mounted on the heat sink surface in a conventional manner.

EXAMPLE IV After dicing the deposited channels and heater wafers into individual printheads, the printheads are deposited on a heat sink having the ink protective coating of the present invention. 0.25
A 10 micron thick coating 34 of an electrophoretically deposited epoxy resin was formed on an inch thick zinc substrate 32. In this particular embodiment, an epoxy resin (Shell Chemical, Houston, Tex., Epon 1009, 2 grams), triethylenetetramine (Milwaukee, Wis., A
ldrich Chemical Co. And 2 g) and cyclohexanone (40 mL) were heated at 85 ° C. for 4 hours and the solution turned red. Further 40
mL of cyclohexanone was added and the solution was allowed to cool to 25 ° C. The resulting solution was then added to methyl isobutyl ketone (280 mL) in a stainless steel beaker acting as a cathode and magnetically stirred. Thus, a colloidal emulsion was formed. 56 more
0 mL of cyclohexanone was added. The zinc heat sink was immersed in the emulsion and then positively charged (as an anode) by applying an electric field of 25 volts for 10 seconds, resulting in coating of the resin film. After air drying, the heat sink coated with the epoxy resin was heated in a furnace at 50 ° C. for 15 minutes, at 100 ° C. for 15 minutes, and at 150 ° C. for 15 minutes to cure a 10-micron thick film. Thereafter, the heat sink was immersed in the ink and left in a furnace at 50 ° C. for a long time. The heater was then withdrawn from the ink reservoir periodically, washed with a free stream of deionized water to remove the ink from the parts, and then carefully examined under a microscope for evidence of erosion on the coating by the ink. Epoxy resin coating 34 was thus tested in an ink of the type described in Example I at 50 ° C. for 10 days. After this period, the coating had not been affected by the ink at all. The print head 10 is then mounted on a heat sink 30 using epoxy doped with silicone rubber.
And the daughter board was mounted on the heat sink surface in a conventional manner.

Example V Victorex® poly (ether sulfone)
(ICI America, Willington, Del.)
s Inc. Grade 300P) was used as a generally accepted product and chloromethylated, with one chloromethyl group per 4.5 repeating units.
A polymer having the following structure was produced.

[0027]

Embedded image A 500 mL, 3-neck round bottom flask equipped with a condenser, mechanical stirrer, and argon inlet was placed in a silicone oil bath. Dimethoxymethane (45m
L) and methanol (1.25 mL) were added to acetyl chloride (35.3 grams) to produce a solution of chloromethyl ether in methyl acetate. The solution is diluted with 150 mL of 1,1,2,2-tetrachloroethane and then tin tetrachloride (0.3 mL)
Was added using a syringe. After heating the solution to an oil bath temperature of 50 ° C., a solution of poly (ether sulfone) (10 grams) in 125 mL of 1,1,2,2-tetrachloroethane was added rapidly. The reaction mixture was heated to reflux at an oil bath temperature set at 110 ° C.
Heating is continued for 16 hours, then the reaction mixture is
Allowed to cool to ° C. The reaction mixture was then added to methanol (1 gallon) and the polymer was precipitated using a Waring blender. The polymer was then filtered and dried under vacuum. The resulting polymer (10 grams)
3. Identified using 1H NMR spectroscopy technique;
Every 5 repeating units had one chloromethyl group.

Example VI Chloromethylated polysulfone (prepared as described in Example V) was added to a solution of 4 grams of polymer in 86 grams of N-methylpyrrolidinone in 504 mL of acetone with magnetic stirring. To produce an electrodeposition bath consisting of a colloidal emulsion of 400 mL of the emulsion to be the cathode
Transferred to a stainless steel beaker. A zinc heat sink was immersed in the coating bath and used as the anode (working piece). When the electrodes were charged with 100 volts DC, the current dropped from an initial value of 8 mA to 1 mA in 30 seconds.
Remove the polymer-coated heat sink from the bath,
Heated at 150 ° C. for 30 minutes. When the heat sink was immersed in the tank again and charged with 100 VDC for 30 seconds,
The current dropped from 1 mA to 0.01 mA. The coated heat sink was then heated to 150 ° C.
For 30 minutes. The coated heat sink was immersed again in the electrophoresis bath and energized for 30 seconds to 100 VDC. The coated piece was taken out of the bath and heated at 150 ° C. for 16 hours. The heat sink had a 10 micron pin-hole free cross-linked poly (ether sulfone) pinhole covering the entangled shapes and fissures required for ink jet design. When a zinc heat sink was repeatedly electrodeposited using an electrodeposition emulsion of poly (ether sulfone) without chloromethyl groups, the electrodeposited film cracked due to burning and was difficult to repair. The electrodeposited poly (ether sulfone) with chloromethyl groups was cured by the formation of methylene bridges and the loss of hydrochloric acid upon heating at 150 ° C. Crosslinking of the poly (ether sulfone) film prevents cracking and allows for repeated electrodeposition.

Example VII A 1 liter, 3-neck, 1 liter round bottom flask equipped with a Barrett trap, condenser, mechanical stirrer, argon inlet, and stopper was placed in a silicone oil bath. . 4,4′-dichlorobenzophenone (manufactured by Aldrich, 50 grams), bisphenol A (manufactured by Aldrich, 48.
96 grams), potassium carbonate (65.56 grams),
Anhydrous N, N-dimethylacetamide (300 mL) and toluene (55 mL) were added to the flask and heated to 175 ° C. (oil bath set temperature) with constant stirring. After 48 hours, the reaction mixture was filtered and methanol (2 gallons)
And washed with water (1 gallon) followed by methanol (1 gallon). The polymer was filtered and dried under vacuum to recover 77.4 grams of polymer. Capacitors,
500- with mechanical stirrer and argon inlet
An mL 3-neck round bottom flask was placed in the silicone oil bath. A solution of methyl acetate and chloromethyl ether was diluted with dimethoxymethane (45 mL) and methanol (1.
(25 mL) mixture was added by adding acetyl chloride (35.3 grams). 15
Dilute with 0 mL of 1,1,2,2-tetrachloroethane, then add tin tetrachloride (0.3 mL) via syringe. After heating the solution to an oil bath temperature of 50 ° C.,
A solution of poly (arylene ether ketone) (10 grams) in 25 mL of 1,1,2,2-tetrachloroethane was added rapidly. The reaction mixture was heated to reflux at an oil bath temperature setting of 110 ° C. Heating was continued for 16 hours, then the reaction mixture was allowed to cool to 25 ° C. The reaction mixture was then added to methanol (1 gallon) using a Waring blender to precipitate the polymer, then filtered and dried under vacuum. The resulting polymer (10 grams) was measured using 1H NMR spectroscopy, and was measured for 1 unit per repeat unit.
It had 5 chloromethyl groups. The polymer was found to have Mn 1 as determined using gel permeation chromatography.
2,000, Mpeak 26,000, Mw 41,
000 and Mz 97,000. The polymer had the following structure.

[0030]

Embedded image Example VIII An electrodeposition bath consisting of a colloidal emulsion of chloromethylated poly (arylene ether ketone) (prepared as described in Example VII) contains 4 grams of polymer in 86 grams of N-methylpyrrolidinone. Was prepared by adding to 504 mL acetone with magnetic stirring. This emulsion was transferred to a 400 mL stainless steel beaker that served as the anode. A zinc heat sink was immersed in the coating bath and used as a cathode (working piece). When 100 VDC is applied to the electrodes, the current is 4
It dropped from an initial value of 0 mA to 10 mA. Remove the polymer-coated heat sink from the bath,
Heated at 150 ° C. for 30 minutes. The heat sink was immersed again in the bath, and 100 VDC was applied for 60 seconds. in the meantime,
The current dropped from 10 mA to 1 mA. The coated heat sink was then heated at 150 ° C. for 30 minutes.
Heated for minutes. Again, the coated heat sink was immersed in the electrophoresis bath and energized to 100 VDC for 60 seconds. The coated piece was taken out of the bath and heated at 150 ° C. for 16 hours.
The heat sink had an 8 micron coating of pinhole-free crosslinked poly (arylene ether ketone) covering the entangled features and cracks required by the ink jet design. Electrodeposited poly (arylene ether ketone) with chloromethyl groups was cured by the formation of methylene bridges and loss of hydrochloric acid upon heating at 150 ° C. Crosslinking of the poly (arylene ether ketone) film prevents cracking and allows repeated electrodeposition.

EXAMPLE IX The present invention can also be used to prevent ink corrosion of other types of metal substrates. As an example, a nickel-copper (alloy 42) substrate is made of chloromethylated poly (arylene ether ketone) and chloromethylated poly (ether sulfone).
And electrophoretically coated. Alloy 60 parts were prepared at 0.1 weight percent solids, Z6020, Z6030,
Z6040 or Z6076 (Dow Corni
ng is commercially available) and then heated at 100 ° C. for 10 minutes. Example VI Using Chloromethylated Poly (arylene ether ketone)
Two aluminum electrodes were placed 1 to 3 cm away from the alloy 42 part immersed in the electrodeposition bath prepared as described in II. For cathodic electrodeposition of Alloy 42 parts, a constant voltage of 50-100 volts was sufficient. Application of 80 volts DC for 90 seconds resulted in an electrodeposited film, which after curing at 250 ° C. for 2 hours, had a thickness of 10 microns. The current is
During the electrodeposition process, it was reduced from 60 mA to 20 mA. The electrodeposited film without the use of the co-catalyst was obtained by heat aging at 260 ° C. for 2 hours.
2 could not be glued. Alloy 42 parts
Electrodeposition was similarly performed in a chloromethylated poly (ether sulfone) bath prepared as described in Example VI. Alloy 42
The anodic electrodeposition of the component was performed using a parallel electrode (cathode) 1 to 3 cm away from the working piece. DC 10
A 20 micron thick film was obtained within 90 seconds at 0 volts. After the film is pulled out of the coating tank,
Heated at 150 ° C. for 1 hour. The electrodeposited film
No cracks and corrosion resistance to pH 10 ink.

EXAMPLE X N-methylpyrrolidone (71 mL) containing poly (arylene ether ketone) having 1.5 chloromethyl groups per repeat unit (10 grams made as described in Example VIII) was converted to acrylic acid Stirred with sodium (5.71 grams) for one week. The reaction mixture is centrifuged, the supernatant is added to methanol (3 liters) using a Waring blender to precipitate the polymer, the polymer is filtered and the polymer is washed with water (1 liter). ) And then washed with methanol (1 liter). The vacuum dried polymer having 0.75 acrylate groups and 0.75 chloromethyl groups per repeat unit had the following structure:

[0033]

Embedded image Example XI An electrodeposition bath consisting of a colloidal emulsion of acryloylated-chloromethylated poly (arylene ether ketone) (prepared as described in Example X) was prepared using 86 grams of 4 grams of polymer. A solution in N-methylpyrrolidinone was added to 504 mL of acetone with magnetic stirring to form. The emulsion was transferred to a 400 mL stainless steel beaker that served as the anode. A zinc heat sink was immersed in the coating bath and used as a cathode (working piece). 100 DC electrodes
Upon charging the volts, the current dropped from an initial value of about 40 mA to about 10 mA over one minute.
The polymer coated heat sink was removed from the bath and
Heat at 0 ° C. for 30 minutes. When the heat sink is immersed in the bath again and charged with 100 VDC for 60 seconds, the current becomes 1
It dropped from 0 mA to 1 mA. The coated heat sink was then heated at 150 ° C. for 30 minutes. Again, the coated heat sink was immersed in the electrophoresis bath, energized with 100 VDC for 60 seconds, removed from the bath, and heated at 150 ° C. for 30 minutes. The electrodeposition process at 100 VDC was performed once more for another minute and the coated working piece was heated at 150 ° C. for 30 minutes. A fifth and final electrodeposition at 100 VDC was performed for 60 seconds. The coated pieces were removed from the bath and heated at 150 ° C. for 16 hours. The heat sink is a pinhole-free, cross-linked poly (arylene ether ketone) 8 that covers the entangled shapes and fissures required by the inkjet design.
It had a micron coating. A total of five electrodepositions were required to remove all pinhole defects in the coating on the zinc substrate. Crosslinking of the polymer, which may have resulted from the electrical polymerization of the acrylate groups, occurred during the electrodeposition. Further crosslinking of the resin occurred during the thermosetting period.

While the embodiments disclosed herein are preferred, it will be understood from this teaching that various alternatives, modifications, variations and improvements may be made by those skilled in the art. Suitable polymers include polysulfone, polyamide,
Polyimide, polyamide-imide, epoxy resin, polyterimide, polyarylene ether ketone, chloromethylated polyarylene ether ketone, acryloylated polyarylene ether ketone, and chlorometholated polyethersulfone, and acryloylated polyethersulfone, polystyrene And other polymers selected from the group consisting of these mixtures.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view of a thermal ink jet printer showing a heat sink having an ink resistant polymer coating layer electrophoretically formed on the heat sink surface.

[Explanation of symbols]

 8 Nozzle 10 Print Head 11 Channel Plate 12 Heater Plate 13 Electrode Wire Bond 14 Reservoir 15 Inlet 16 Channel 18 Insulating Layer 20 Daughter Board 21 Inclined End 22 Address Electrode 23 Arrow 24 Ink Flow Bypass Pit 25 Heating Element 26 Pit 27 Insulating Layer 28 Insulation layer 29 Nozzle surface 30 Wire bond 31 Electrode attachment terminal 32 Zinc substrate 34 Polymer coating 35 Heat sink

Continued on the front page (72) Inventor Timothy Jay Fuller New York, USA 14534-4023 Pittsford Railroad Mills Road 67

Claims (3)

[Claims] 1. A thermal inkjet printer for discharging a recording liquid onto a recording medium, comprising: a print head including at least one channel for holding the recording liquid; and discharging the recording liquid onto the recording medium. At least one nozzle for heating the ink in the channel to cause the ink in the channel to be ejected from the nozzle, the printhead having a polymer thereon. A thermal ink jet printer wherein a coating of material is mounted on a heat sink comprising an at least partially conductive metal substrate electrophoretically deposited. 2. A printing system in which a thermal inkjet printhead discharges a recording liquid onto a recording medium, comprising:
A print head comprising: at least one chamber for holding the recording liquid; at least one nozzle for discharging the liquid onto a recording medium; and a channel for providing a liquid flow path between the chamber and the nozzle. Means for introducing energy into the liquid contained in the channel; and selectively energizing the energy generating means for periodically discharging the liquid through the nozzle onto the recording medium. Means for attaching the printhead to the surface of an at least partially conductive heat sink substrate for transferring heat away from the printhead, the substrate comprising: A printing system having a thin polymeric material coated thereon. 3. A method of depositing an ink jet print head on a heat sink substrate, comprising: (a) providing an at least partially conductive heat sink substrate; and (b) electroplating comprising charged micelles of a polymeric material. Providing a bath, (c) a heat sink substrate acting as a first electrode;
Placing a second electrode in the bath; and (d) applying an electric field across the electrode for a time sufficient to electrophoretically deposit the polymer coating on the surface of the heat sink substrate to a desired thickness; (E) removing the substrate from the emulsion, drying the coated heat sink substrate, and (f) adhering the printhead to the coated substrate surface.