The disclosure relates to micro-fluid ejection heads and in particular to protection devices for orifice plates of the ejection heads.
Micro-fluid ejection devices have continued to find application in a variety of fields including, but not limited to, ink jet printing, micro-fluid heat transfer, micro-biological preparations, pharmaceutical delivery and the like. As higher quality ejection devices are produced, it becomes increasingly important to protect the orifice plates on the ejection heads during handling, storage, and shipping of the devices so that contamination of fluids or plugging of orifices does not occur. Conventionally, cover tapes are applied to the orifice plates and are removed prior to use of the devices. The cover tapes should be sufficient to adequately seal the orifices to prevent evaporation and intermixing of fluids and should be constructed of materials that are resistant to and do not contaminate the fluids. Removal of the cover tapes should also not leave undesirable residue on the orifice plate.
Pressure sensitive adhesive (PSA) tapes have been used as cover tapes. The PSA tapes are generally constructed of a base film with an acrylate based PSA layer used to seal the orifices on the orifice plate. The base film is typically made of polyethylene terephthalate commonly referred to as polyester (PET) or polyvinyl chloride (PVC).
The acrylic PSA layer is a polymer that can swell (absorb liquids). Accordingly, the PSA layer may be viewed as a polymeric sponge above its glass transition temperature. Typically, the glass transition temperature of acrylic PSA's is at or below about 0° C. Therefore, at any temperature above the glass transition temperature, the adhesive has a high propensity to swell and to flow. During micro-fluid ejection head manufacturing, the ejection head is at or above room temperature. Hence, the PSA layer attached to the orifice plate is constantly absorbing fluid components until an equilibrium point is reached and the adhesive is saturated. Once saturated at the elevated temperature, the acrylic PSA material can flow into the nozzle holes and plug or clog the nozzle holes.
Another disadvantage of an acrylic based PSA cover tape is that a cohesive strength of the PSA is weak with respect to the base film. When the tape is removed from the nozzle plate, the adhesive may be left in the nozzle holes causing a clogged nozzle and/or misdirected fluid. As the nozzle holes get smaller, it is harder to remove PSA material that has swelled in the nozzle holes.
Accordingly, there is a need for improved orifice plate protection devices containing improved adhesives that reduce fluid leakage, fluid evaporation, contamination, and fluid intermixing, and that are easily removable from the orifice plate while minimizing the amount of unwanted residue left on the orifice plate. There is also a need for improved methods for sealing the nozzle holes of an orifice plate for a micro-fluid ejection head.
With regard to the foregoing, the disclosure provides an orifice plate sealing tape for an orifice plate of a micro-fluid ejection device. The sealing tape includes a radiation curable adhesive for application adjacent to a surface of the orifice plate and a flexible polymeric backing film in adhesive contact with the adhesive. The adhesive is curable in a pattern sufficient to seal adjacent to nozzle holes in the orifice plate and to enhance removal of the backing film and adhesive from the orifice plate prior to use of the micro-fluid ejection device.
In another embodiment, there is provided a method of sealing an orifice plate for a micro-fluid ejection device to prevent leakage and evaporation of fluid from the device during handling and shipping. The method includes applying a radiation curable adhesive and backing film to a surface of the orifice plate. The adhesive is cured in a pattern sufficient to seal adjacent to nozzle holes in the orifice plate and to enhance removal of the backing film and adhesive from the orifice plate prior to use of the micro-fluid ejection device.
In yet another embodiment, there is provided a method for enhancing sealing tape and adhesive removal from an orifice plate for a micro-fluid ejection device. The method includes applying a patterned adhesive and backing film to a surface of the orifice plate. The adhesive and film are exposed to radiation sufficient to at least partially cure the adhesive.
Another exemplary embodiment provides a micro-fluid ejection head attached to a fluid cartridge body. The micro-fluid ejection head has an orifice plate with a backing film and radiation curable adhesive applied to a surface of the office plate for sealing nozzle holes in the orifice plate. The adhesive is curable in a pattern sufficient to seal adjacent to nozzle holes in the orifice plate and to enhance removal of the backing film and adhesive from the orifice plate prior to use of the micro-fluid ejection head.
Advantages of exemplary embodiments described herein include, but are not limited to, an ability to adjust the amount of adhesion between a nozzle plate sealing tape and a nozzle plate of a fluid ejection device. Another advantage is that the tape may be removed from the nozzle plate with a minimum of residue left on the nozzle plate and in nozzle holes of the nozzle plate. Yet another advantage is that the cured adhesive may have less affinity for the fluids ejected through the nozzle holes and thus may exhibit less deterioration over time thereby improving the sealing capabilities of the tape.
Further features and advantages of exemplary embodiments disclosed herein may become apparent by reference to the detailed description when considered in conjunction with the figures, which are not to scale, wherein like reference numbers indicate like elements through the several views, and wherein:
With reference to
The protective tape 16 is used to protect the contacts 18 on the flexible circuit 20 from contamination and damage, and to seal nozzle holes 24 in the nozzle plate 22 so that the fluid in the cartridge 10 does not leak out or dry and plug the nozzle holes 24. Before the cartridge 10 is installed in a device, such as a printer, for causing fluid to be ejected through the nozzle holes 24, the tape 16 is pealed away from the cartridge body 12 by grasping a tab 26 on one end 28 of the tape 16 and pulling the tape 16 away from the cartridge body 12 as shown schematically by
As shown in more detail in
The second component of the tape 16 shown in
In another exemplary embodiment, irradiation of the adhesive may be effective to reduce adhesion between the surface 34 of the nozzle plate 22 and the adhesive layer 32.
In yet another exemplary embodiment, described in more detail below, an adhesive layer may be applied to a surface of the nozzle plate 34 rather than to the backing film 30.
The pressure sensitive adhesive layer 32 may be made from various radiation curable polymers such as epoxy, diolefin, urethane, polyimide, acrylic, silicone and vinyl ester polymers including a polymerization initiator. Examples of acrylic polymers which may be used include homopolymers or copolymers of an alkyl(meth)acrylate, and copolymers of (meth)acrylate and another copolymerizable monomer such as a hydroxyalkyl(meth)acrylate, glycidyl(meth)acrylate, (meth)acrylic acid, itaconic acid, maleic anhydride, (meth)acrylic amide, (meth)acrylic N-hydroxymethylamide, an alkylaminoalkyl(meth)acrylate, silicone adducted acrylate, vinyl acetate, styrene or acrylonitrile.
Acrylic polymers useful as the adhesive typically have a weight-average molecular weight of at least about 200,000 to about 2,000,000. The glass transition point of such an acrylic polymer is about 0° C. or less, and may be from about −100° C. to about −20° C., so that it exhibits tackiness at room temperature (about 25° C.). Pressure-sensitive adhesive polymers may be used either singly or in combination. An acrylic polymer may be converted into a reactive polymer that may be cured by exposure to ultraviolet rays, by introducing a carbon-to-carbon double bond in its main chain or side chain.
Carbon-to-carbon double bonds that may be introduced into the acrylic polymer include, but are not limited to, a monomer or oligomer having, in a molecule thereof, a carbon-to-carbon double bond and being curable by radical polymerization. Specific examples of such monomers or oligomers include esters of (meth)acrylic acid and a polyhydric alcohol such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tetraethyleneglycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentylglycol di(meth)acrylate and dipentaerythritol hexa(meth)acrylate, ester acrylate oligomers, isocyanurate, isocyanurate compounds such as 2-propenyldi-3-butenyl cyanurate, 2-hydroxyetrhylbis(2-acryloxyethyl)isocyanurate and tris(2-methacryloxyethyl)isocyanurate and various urethane oligomers. The above-exemplified materials are usually included in an adhesive formulation in an amount ranging from about 5 to about 200 parts by weight based on 100 parts by weight of the adhesive formulation.
Epoxy polymers may also be used as the base or as an additive to the adhesive layer 32. The epoxy polymers may be converted into reactive polymers by exposure to UV radiation and/or heat thereby opening the epoxy ring to provide reactive sites. Specific examples of epoxy monomers that may be used adhesive layers 32 include diglycidyl ether bisphenol-A (DGEBA) epoxy monomers available from Resolution Performance Products, LLC of Houston, Tex. under the trade names EPON 1001, EPON 1007 and EPON SU-8. Plasticizers may be added to the base epoxy polymers to increase the flexibility of the adhesive layer 32. Such plasticizers include, but are not limited to, low molecular weight DGEBA epoxy resins, polyols, polyacrylates, phenoxy compounds, polybutenes, and mineral oil. An exemplary epoxy adhesive formulation that may be used includes from about 10 to about 50 percent by weight difunctional epoxy compound, from about 5 to about 30 percent by weight plasticizer, from about 1 to about 10 percent by weight photoinitiator, and from about 20 to about 80 percent by weight of non reactive solvent.
In addition to the acrylic and epoxy adhesive materials described above, polyimide and silicone based materials may also be used as base materials for the pressure sensitive adhesive layer 32. In all cases, the adhesive materials may be staged on the backing film 30 to provide the pressure sensitive adhesive tape 16. The adhesive layer 32 may be coated onto the backing film 30 using either flexographic, gravure or screen printing techniques. After coating the backing film 30 with the adhesive layer 32, the backing film 30 is heated to remove the solvent and to “b stage” the adhesive layer 32 on the backing film 30. At this point, the adhesive layer 32 is still tacky, and not fully cured. Curing of the adhesive layer 32 takes place through an ultraviolet radiation exposure.
In order to provide a tape 16 that is radiation curable, a photoinitiator may also be included in the adhesive formulation. A suitable photoinitiator is a photoinitiator that is activated by exposure to ultraviolet radiation. Such photoinitiators include, but are not limited to, 1-hydroxycyclohexyl phenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyldiphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, beta-chloroanthraquinone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. The photoinitiator is preferably used in an amount ranging from about 0.4 to about 20 wt. % based on 100 parts by weight of the adhesive formulation. Other components of the adhesive formulation may include plasticizers, surfactants, tackifiers, fillers and/or colorants which are used in conventional amounts.
Typically, a pressure sensitive tape 16 as shown in
As mentioned above, a nozzle sealing tape constructed of a thermoplastic backer and a UV initiated adhesive are provided. Exemplary embodiments described herein relate to various useful sealing tape constructions and methods of sealing nozzle holes in the nozzle plate 22. In a first exemplary embodiment, a sealing tape is constructed ahead of time by coating an adhesive onto a thermoplastic backer film. The tape is then applied to the nozzle plate surface and then irradiated with UV radiation, for example. In a second exemplary embodiment, an adhesive is dispensed onto the nozzle plate surface and then a backer film is applied to the adhesive and the nozzle plate prior to irradiating the tape with UV radiation.
With reference to
Once initial contact is made between the adhesive layer 32 of the tape 16 and the nozzle plate surface 34, the adhesive would be exposed to UV light or another suitable source of radiation to initiate a crosslinking reaction in the adhesive layer 32 to selectively adjust an adhesive strength of the adhesive. The adhesive strength of the adhesive may be tailored to have a low amount of adhesion between 0.1 to 1 N/mm with the nozzle plate surface 34 in order to enhance complete removal of residual adhesive from the surface 34 of the nozzle plate 22. For example, the adhesive strength of the adhesive may be tailored by adjusting the amount of hydroxyl and epoxy groups in an epoxy resin monomer used as the adhesive. By reducing the available sites for bonding, the adhesion strength may be decreased. However, the adhesive strength should remain sufficient to seal adjacent to the nozzle holes 24 so as to prevent fluid leakage from the nozzle plate 22 and to prevent fluid from drying in the nozzle holes 24.
The tape 16 containing the adhesive layer 32 may be exposed to ultraviolet radiation in a pattern sufficient to seal adjacent to the nozzle holes 24. In
In
In
Other exemplary embodiments are illustrated in
In any of the patterned curing of the adhesive illustrated in
After attaching the tape 60 to the cartridge body 12, the tape 60 is exposed to radiation 62 from a radiation source 64 to lessen or decrease the adhesion of the tape to the nozzle plate surface 34, at least in the unshaded patterns 24, 46 and 48 illustrated in
In all of the embodiments described above, exposure of the ejection head to intense UV radiation may reduce or eliminate bacterial or fungi/mold contamination of the fluids contained in the cartridge body 12. Such benefit of UV radiation is particularly useful in the case of ink as the fluid in the cartridge body 12 as UV radiation may supplement or possibly eliminate the need for a biocide in the ink formulation.
In the above exemplary embodiments, the fluid cartridge 10 containing the ejection head 14 may be used in a fluid ejection device such as an ink jet printer, wherein the fluid ejected is ink. Other micro-fluid ejection devices that may use the ejection head 14 and fluid cartridge 10 may include, without limitation, lubrication ejection heads, cooling ejection heads, and pharmaceutical ejection heads.
Having described various aspects and exemplary embodiments of the disclosure and several advantages thereof, it will be recognized by those of ordinary skills that the exemplary embodiments are susceptible to various modifications, substitutions and revisions within the spirit and scope of the appended claims.
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Number | Date | Country | |
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20060221119 A1 | Oct 2006 | US |