Silicone tape having improved adhesive properties

Abstract

To provide a removable tape configured for sealing the nozzle plate of an ejection head and a method for making the removable tape.SOLUTION: A removable tape includes: a polymeric backing film; a first platinum-cured silicone adhesive layer having a first adhesive strength applied to the polymeric backing film; and a second platinum-cured silicone adhesive layer having a second adhesive strength applied to the first adhesive layer. The second platinum-cured silicone adhesive layer is configured to adhere to the nozzle plate of a fluid ejection cartridge.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to the field of fluid ejection cartridges. More specifically, the present invention relates to an improved sealing tape for use on fluid ejection cartridges. [Background technology]

[0002] Thermal inkjet printing has been around for decades as a method of ejecting fluids onto a substrate. Traditionally, inkjet printers have typically been used to print water-based inks onto paper in home or office facilities. However, the inkjet printing market is now shifting to commercial and industrial applications due to a decline in home printing. Commercial inkjet printing consumers use aggressive solvent and ink formulations to print on a variety of materials, including steel, glass, and cardboard. Thus, this shift creates a demand for fluid ejection heads and cartridges that are durable for use with non-traditional fluid formulations.

[0003] In some examples, the majority of a fluid ejection cartridge's life is spent in shipping from the manufacturer and / or in storage prior to installation or use. Therefore, even if the cartridge remains in storage for an extended period of time, it is important that the operability of the cartridge is not compromised during shipping and storage. Typically, to maintain the cartridge in operability, a plastic cover including a protective sealing tape or an elastomeric seal covers the ejection head and the ejection nozzles on the ejection head. Both the plastic cover and the sealing tape are designed to prevent tampering of the ejection head during shipping and storage, to prevent fluid leaching from the ejection head, and to reduce the amount of solvent that evaporates from the fluid within the cartridge. The plastic cover or sealing tape is removed from the fluid ejection cartridge prior to use, exposing the ejection nozzles. Although the plastic cover is effective in maintaining operability, it is significantly more expensive than the protective sealing tape. Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional pressure sensitive adhesive (PSA) sealing tapes used to seal the nozzle holes of the ejection head typically include an acrylic adhesive with a polyvinyl chloride or polyethylene terephthalate backing film. Although these conventional acrylic adhesives are suitable for use with water-based inks, they can be dissolved by the more aggressive solvents and fluid formulations used in commercial and industrial applications, causing fluid leakage from the fluid ejection cartridge and / or premature peeling of the tape from the ejection head. Therefore, to ensure that the protective sealing tape does not peel prematurely from the ejection head, a suitable tape and adhesive system must be found that is not easily dissolved by these aggressive solvents and ink formulations. The sealing tape must also be stable when exposed to heat during shipping and storage, and must be completely removable from the ejection head while remaining attached to the backing film and without leaving adhesive residue or damaging the nozzle plate of the underlying printhead. Thus, there is a need for an improved adhesive tape sealing system that can be used with fluid ejection cartridges containing a variety of fluids and solvents.

[0005] In view of the above, one embodiment of the present invention provides an improved removable tape for fluid ejection cartridges and a method for manufacturing the improved removable tape. An advantage of the disclosed embodiment is that the removable adhesive tape material can be tailored for fluid ejection cartridges containing a variety of fluids and solutions by using a backing material having two layers of platinum-cured adhesive material with different peel strengths. The removable adhesive tape material can also be tailored to have improved chemical resistance to fluids used in fluid ejection cartridges by having a larger thickness of the adhesive layer with a relatively high adhesive strength applied directly to the backing material. [Means for solving the problem]

[0006] In one aspect of the invention, a removable adhesive tape is configured to seal a nozzle plate attached to an ejection head and a portion of a fluid ejection cartridge body housing the ejection head. The removable tape includes a polymer backing film, a first platinum-cured silicone adhesive layer having a first adhesive strength applied to the polymer backing film, and a second platinum-cured silicone adhesive layer having a second adhesive strength applied to the first adhesive layer. The second platinum-cured adhesive layer is configured to adhere to a nozzle plate on the ejection head of the fluid ejection cartridge.

[0007] In some embodiments, the polymeric backing film may be selected from polyethylene terephthalate (PET), polypropylene, polyamide, and polyimide.

[0008] In some embodiments, the polymeric backing film has a thickness in the range of about 20 to about 30 microns, the first platinum cured silicone adhesive layer has a thickness in the range of about 7 to about 20 microns on the polymeric backing film, and the second platinum cured silicone adhesive layer has a thickness in the range of about 7 to about 20 microns on the first platinum cured silicone adhesive layer.

[0009] In some embodiments, the polymeric backing film may include a corona-treated polymeric backing film.

[0010] In some embodiments, the first adhesive strength is greater than the second adhesive strength.

[0011] In some embodiments, the first platinum-cured silicone adhesive layer and the second platinum-cured silicone adhesive layer may comprise different platinum-cured silicone adhesive substrates.

[0012] In some embodiments, the first platinum cured silicone adhesive substrate and the second platinum cured silicone adhesive substrate are different, and the first adhesive strength may have a peel strength on a dry silicon wafer in the range of about 150 to about 500 Newtons per meter (N / m) and the second adhesive strength has a peel strength on a dry silicon wafer in the range of about 25 to about 65 N / m.

[0013] In some embodiments, the first platinum-cured silicone adhesive layer and the second platinum-cured silicone adhesive layer may comprise the same platinum-cured adhesive substrate.

[0014] In some embodiments, the first platinum cured silicone adhesive substrate and the second platinum cured silicone adhesive substrate are identical, and the first adhesive strength has a peel strength on a dry silicon wafer in the range of about 150 to about 500 Newtons per meter (N / m), and the second adhesive strength has a peel strength on a dry silicon wafer in the range of about 25 to about 65 N / m.

[0015] In another embodiment, the present invention provides a method for making a removable tape configured to seal a nozzle plate. The method includes providing a polymeric backing film and mixing a crosslinker mixture including a platinum siloxane complex catalyst, polydimethylsiloxane (PDMS) and polymethylhydrosiloxane (PMHS) with a first platinum-cured silicone adhesive substrate to provide a first platinum-cured silicone adhesive and with a second platinum-cured silicone adhesive substrate to provide a second platinum-cured silicone adhesive. The method further includes applying a first layer of the first platinum-cured silicone adhesive having a first adhesive strength to the polymeric backing film and applying a second layer of the second platinum-cured silicone adhesive having a second adhesive strength to the first layer. The method further includes curing the first adhesive layer and the second adhesive layer.

[0016] In certain embodiments, the method includes sequentially curing a first layer and a second layer of platinum-cured silicone adhesive. In one variation of this embodiment, the curing step includes first partially curing the first layer of platinum-cured silicone adhesive at a temperature of at least about 90° C. for about 1 minute, and then co-curing the first and second layers of platinum-cured silicone adhesive at a temperature ranging from about 120° C. to about 150° C. for about 2 minutes to about 3 minutes.

[0017] In certain embodiments, the method includes simultaneously curing the first and second layers of platinum cured silicone adhesive. In one variation of the invention, the first and second adhesive layers are simultaneously cured at a temperature ranging from about 120° C. to about 150° C. for about 2 minutes to about 3 minutes.

[0018] In certain embodiments, the first platinum-cured silicone adhesive layer and the second platinum-cured silicone adhesive layer comprise different platinum-cured adhesive substrates.

[0019] In certain embodiments, the first platinum-cured silicone adhesive layer and the second platinum-cured silicone adhesive layer comprise the same platinum-cured adhesive substrate.

[0020] In a variation of this embodiment where the first adhesive substrate and the second adhesive substrate are the same, the method may further include combining a first amount of the crosslinker mixture with the first platinum-cured silicone adhesive substrate and combining a second amount of the crosslinker mixture with the second platinum-cured silicone adhesive substrate, wherein the second amount of the crosslinker mixture is greater than the first amount of the crosslinker mixture.

[0021] In another embodiment, the present invention provides a method for improving sealing of a nozzle plate of a discharge head attached to a fluid discharge cartridge containing a fluid. The method includes providing a cartridge body having a cover closing a first end, a discharge head on a second end opposite the first end, and a sidewall attached to the first end and the second end between the first end and the second end. The sidewall includes a first sidewall, a second sidewall opposite the first sidewall, a first end wall attached to the first sidewall and the second sidewall, and a second end wall opposite the first end wall attached to the first sidewall and the second sidewall. The method further includes attaching a removable tape to the nozzle plate of the discharge head and a portion of the cartridge body. The removable tape includes a polymeric backing film and a modified platinum-cured silicone adhesive layer, the adhesive layer having a first adhesive strength adjacent to the backing film and a second adhesive strength adjacent to the nozzle plate that is less than the first adhesive strength.

[0022] In some embodiments, the first adhesive strength has a peel strength on a dry silicon wafer in the range of about 150 to about 500 Newtons per meter (N / m), and the second adhesive strength has a peel strength on a dry silicon wafer in the range of about 25 to about 65 N / m.

[0023] In some embodiments, the modified platinum cured silicone adhesive layer has a thickness in the range of about 20 to about 30 microns on the polymeric backing film.

[0024] The disclosed embodiments provide a unique adhesive tape having two adhesive layers configured to provide a removable protective tape for the ejection head of a fluid cartridge suitable for use with a variety of ejection fluids. [Brief description of the drawings]

[0025] Further advantages of the present invention will become apparent from the detailed description taken in conjunction with the drawings, which are not to scale to more clearly show detail and in which like reference numerals refer to like elements throughout the several views. [Figure 1]FIG. 1 is a side perspective view of a fluid ejection cartridge according to one embodiment of the present invention. [Diagram 2] 2 is an end perspective view of the fluid ejection cartridge of FIG. 1. [Diagram 3] 2 is a top perspective view of the fluid ejection cartridge of FIG. 1. [Figure 4] FIG. 2 is an exploded view, not to scale, of the fluid ejection cartridge of FIG. [Diagram 5] 2 is a perspective, not to scale, view of a protective sealing tape and pull tape for protecting the ejection head of the fluid ejection cartridge of FIG. 1. FIG. [Figure 6] 1 is a cross-sectional view, not to scale, of a protective closure tape according to a first embodiment of the present invention. [Figure 7] FIG. 2 is a cross-sectional view, not to scale, of a protective closure tape according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] 1, there is shown a fluid ejection cartridge 10 including a protective sealing tape 12 and a pull tape 14 overlapping a portion 16 of the protective sealing tape 12. The protective sealing tape 12 is used to cover a nozzle plate 18 of an ejection head 20 attached to the fluid ejection cartridge 10. The protective sealing tape 12 prevents the ejection head 20 from being contaminated with foreign matter and being damaged, and seals the nozzle holes of the nozzle plate 18 to prevent fluid within the fluid ejection cartridge 10 from leaking out or drying out and clogging the nozzle holes during transportation and storage of the fluid ejection cartridge 10.

[0027] As shown in FIG. 2, a flexible circuit 22 is electrically connected to the ejection head 20 for controlling ejection of fluid from the fluid ejection cartridge 10 during use of the fluid ejection cartridge 10. The flexible circuit has electrical contacts 24 provided on a first end wall 26 of the fluid ejection cartridge 10 for electrical connection to a fluid ejection device, such as a printer, an inhaler, an e-cigarette, a digital dispensing system, or the like (not shown). A cover 28 is attached to a first end 30 of the fluid ejection cartridge 10 opposite a second end 32 that houses the ejection head 20 of the fluid ejection cartridge. The pull tape 14 and protective sealing tape 12 are removably attached to a fluid ejection cartridge body, such as a first side wall 34 (FIG. 1) of the fluid ejection cartridge 10. The fluid ejection cartridge 10 also includes a second side wall 38 opposite the first side wall 34 and a second end wall 40 opposite the first end wall 26.

[0028] Before cartridge 10 is attached to a fluid ejection device and used, pull tape 14 is peeled from the body of fluid ejection cartridge 10 by grasping a tab at one end of pull tape 14 and pulling pull tape 14 away from the body of fluid ejection cartridge 10. When pull tape 14 is removed from fluid ejection cartridge 10, protective sealing tape 12 attached to pull tape 14 at overlap region 16 is also removed from fluid ejection cartridge 10, allowing fluid to be ejected from ejection head 20.

[0029] Further details of the fluid ejection cartridge 10 can be seen in the exploded view of the fluid ejection cartridge 10, which is depicted generally in Figure 4. The ejection head 20 includes a semiconductor substrate 42 to which the flexible circuit 22 is electrically connected, and the nozzle plate 18 is attached to the semiconductor substrate 42 at a window (not shown) in the flexible circuit 22. In some embodiments, the fluid ejection cartridge 10 is filled with an open cell foam 46 that holds the fluid to be ejected from the ejection head 20 and provides back pressure to the fluid to reduce drooling of the fluid from the ejection head 20. In other embodiments, the body of the fluid ejection cartridge 10 may not have a back pressure device.

[0030] In the embodiment described herein, the protective sealing tape 12 is used to cover and protect the nozzle holes of the nozzle plate 18 as described above. The protective sealing tape 12 has a polymeric base film layer or "backing film" 50 (shown in FIG. 6) in addition to one or more adhesive layers 51 (FIG. 6). The backing film 50 comprises polyethylene terephthalate, polypropylene, polyethylene, polybutene, polybutadiene, polymethylpentene, polybutylene terephthalate, polyurethane, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-(meth)acrylic acid copolymer, ethylene-alkyl meth(acrylate) copolymer, polystyrene, polyimide, polyamide, or polycarbonate and has a thickness in the range of about 10 to about 40 microns, preferably about 20 to about 30 microns. A particularly preferred polymeric backing film material is polyimide.

[0031] It should be appreciated that the ejection head 20, together with its semiconductor substrate 42 and nozzle plate 18, are precision-manufactured devices capable of high-resolution fluid ejection. Thus, protection of the ejection head 20 is important for the proper operation of a fluid ejection device using the cartridge 10. As shown in FIG. 1, a protective sealing tape 12 is affixed to the ejection head 20 and the body of the fluid ejection cartridge 10, and a pull tape 14 is affixed to the body of the fluid ejection cartridge 10 adjacent one end of the protective sealing tape 12. In some embodiments, the protective sealing tape 12 is configured to be peeled from the ejection head 20 in a direction perpendicular to the longitudinal direction of the nozzle plate 18 and substrate 42. Such a peeling direction is effective to reduce possible stresses on the ejection head 20 when the protective sealing tape 12 is peeled off, and to reduce the possibility of the nozzle plate 18 peeling off from the substrate 42. Thus, it is preferred that the protective sealing tape 12 be peeled off in a direction perpendicular to the ejection head, rather than in a longitudinal direction. Furthermore, the adhesive layer 51 or 52 of the protective sealing tape 12, such as the protective sealing tape 12a or 12b (Figures 6 to 7), is in close contact with the nozzle plate 18, and if any residue remains on the nozzle plate 18, it may cause foreign matter to get into the nozzle holes of the nozzle plate 18, preventing the nozzle holes from functioning normally. Therefore, it is important that the protective sealing tape 12 contains almost no residue.

[0032] The protective closure tape 12 includes a front side 58 of the protective closure tape 12 and a back side 54 of the protective closure tape 12. As shown in Figures 1 and 5, it is important that the pull tape 14 overlaps the back side 54 of the protective closure tape 12 to enhance removal of the protective closure tape 12 from the cartridge 10. In the disclosed embodiment, the adhesive material used on the underside 56 of the pull tape 14 is not critical. Thus, the pull tape adhesive may be a pressure sensitive adhesive selected from a variety of radiation curable polymers such as epoxies, diolefins, urethanes, polyimides, acrylics, and silicones, and vinyl ester polymers containing polymerization initiators. Examples of usable acrylic polymers include homopolymers or copolymers of alkyl (meth)acrylates and copolymers of (meth)acrylates with another copolymerizable monomer, such as hydroxyalkyl (meth)acrylate, glycidyl (meth)acrylate, (meth)acrylic acid, itaconic acid, maleic anhydride, (meth)acrylamide, (meth)acrylic N-hydroxymethylamide, alkylaminoalkyl (meth)acrylate, silicone-added acrylate, vinyl acetate, styrene, or acrylonitrile. In addition to acrylic and epoxy adhesive materials, polyimide and silicone materials may also be used as substrates for the pressure-sensitive adhesive layer on the lower side 56 of the pull tape 14. The adhesive used on the lower side 56 of the pull tape 14 has a peel strength of about two times, and preferably at least about three times, the peel strength of the portion in contact with the nozzle plate.

[0033] Platinum-cured silicone adhesives are a suitable adhesive substrate for forming the adhesive layer of the protective closure tape 12 which contacts and seals the nozzle holes in the nozzle plate 18. Platinum-cured silicone adhesives have been found to be particularly chemically resistant to organic solvent-based fluids, thereby maintaining adequate peel strength over extended periods of time while exposed to the organic solvent-based fluids within the cartridge 10. Conventional adhesives, such as acrylic adhesives, peroxide-catalyzed silicone adhesives, natural and synthetic rubber-based adhesives, and hot melt adhesives, are unable to maintain adequate peel strength and / or are unable to remain on the nozzle plate despite relatively high initial peel strength.

[0034] A platinum cured silicone adhesive according to the present invention is prepared by crosslinking the silane groups of a polydimethylsiloxane (Formula I) with a high molecular weight vinyl terminated polydimethylsiloxane (Formula II) in the presence of a platinum catalyst and heating to provide a platinum cured silicone adhesive according to the following reaction:

[0035] [ka]

[0036] The crosslinked platinum-cured silicone adhesives described above are highly resistant to organic solvents and provide a significantly improved adhesive tape for sealing fluid ejection ejection heads. The platinum-cured silicone adhesives described above have been found to withstand harsh environments better than acrylic, rubber, synthetic rubber, acrylic / rubber hybrid, or hot melt adhesives.

[0037] However, one problem that arises with the use of platinum cured silicone adhesives is that the adhesive layer requires adequate adhesion strength at two interfaces: between the adhesive layer and the nozzle plate 18 of the ejection head 20, and between the adhesive layer and the backing film 50. An adhesive layer consisting of a single platinum cured silicone adhesive layer provides a single adhesion strength at both interfaces and presents the possibility of failure within the protective seal tape 12. For example, if the adhesion strength between the adhesive layer and the nozzle plate 18 is too high, removal of the protective seal tape 12 from the ejection head 20 may damage the delicate photoresist layers of the ejection head 20, such as damaging the channels formed between the nozzle plate 18 layer and the fluid flow layer of the ejection head 20, rendering the cartridge non-functional. Similarly, if the adhesion strength between the adhesive layer and the backing film is too low, removal of the protective seal tape 12 from the ejection head 20 may result in the adhesive layer remaining stuck to the ejection head 20, impeding fluid flow from the cartridge 10 and also rendering the cartridge non-functional.

[0038] The conventional method to achieve the necessary balance and prevent failures at the nozzle plate is to add adhesion "suppressors" to the tape formulation to reduce the tape adhesion to an ideal level for both interfaces. For example, acrylic adhesives used to seal printheads containing water-based ink formulations contain plasticizers to reduce adhesion to an acceptable level. However, adhesion suppressors tend to interfere with the chemical resistance of silicone adhesive formulations. Thus, a pure, unmodified silicone adhesive layer is preferred to maintain chemical resistance.

[0039] Furthermore, to increase the adhesive strength between the adhesive layer and the polymeric backing film, a corona treatment of the backing film may be performed before applying the adhesive material onto the backing film. In addition, an adhesion promoter may be added to the highly crosslinked adhesive formulation to improve adhesion between the adhesive and the polymeric backing film. A suitable adhesion promoter is 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, available under the trade name SYL-OFF 9176 from The Dow Chemical Company. The amount of adhesion promoter in the adhesive formulation may range from about 0.2 to about 0.4 weight percent based on the total weight of the adhesive formulation.

[0040] To explore further additional solutions, initial testing of potential suitable adhesive layer materials was performed using a variety of pure and unmodified platinum-cured silicone adhesive substrates offering different adhesion strengths, including materials from The Dow Chemical Company. Some of the materials tested included platinum-cured silicone adhesive substrates under the trade names DOWSIL 7646, DOWSIL 7652, DOWSIL 7667, and DOWSIL 7657. In testing, DOWSIL 7667 was determined to provide an approximately acceptable level of adhesion. DOWSIL 7652 had too little adhesion to the backing film, resulting in residue on the nozzle plate 18, and DOWSIL 7657 had too much adhesion and damaged the photoresist layer of the ejection head 20. DOWSIL 7667 provided somewhat satisfactory adhesion results, but the frequency of adhesion failure at both interfaces was unsatisfactory.

[0041] To solve the interfacial adhesion problem, it was determined whether an adhesive could be formed from multiple layers of a platinum-cured silicone adhesive substrate. By utilizing similar chemistry and the same crosslinking mechanism as the platinum-cured silicone adhesive substrate, an adhesive layer with a rigid high adhesion structure on the side facing the backing film and a soft low adhesion structure on the side facing the nozzle plate can be created.

[0042] In the exemplary embodiment shown in Figure 6, the adhesive layer 51 of the closure tape 12a can include two different layers. The first adhesive layer 60, which contacts the backing film 50, can include an adhesive base that exhibits excellent crosslinking and high adhesion in the cured form at the expense of reduced wettability, such as DOWSIL 7657. The second adhesive layer 62 is applied to the first adhesive layer. The second adhesive layer 62 configured to contact the nozzle plate 18 may include one or more adhesive substrates that exhibit relatively low crosslinking and relatively low adhesion in a cured form, such as DOWSIL 7652, or alternative compositions of adhesive substrates that combine relatively low adhesion substrates, such as DOWSIL 7652 or DOWSIL 7646, with substrates having relatively high adhesion and chemical resistance, such as DOWSIL 7667, in various ratios to provide acceptable bond strength, such as, but not limited to, 90% DOWSIL 7667 and 10% DOWSIL 7652 or DOWSIL 7646, or other platinum cured silicone adhesive substrates.

[0043] In another embodiment, the first adhesive layer 60 and the second adhesive layer 62 may comprise the same adhesive substrate, but the adhesive strength may be effectively "constrained" to an acceptable level based on the molar ratio of crosslinker (I) added to the adhesive substrate containing PDMS (II). This single adhesive substrate method may reduce the manufacturing cost of the tape by eliminating the use of two different silicone adhesive substrates to make the adhesive layer 51, and may trade some chemical resistance of the modified material for adhesive strength properties that can be easily modified and optimized for various other applications while maintaining purity. In applications that optimize adhesive substrate adhesive strength, the ideal molar ratio of crosslinker (I) to PDMS (II) in the adhesive substrate is 2:1, which provides a 1:1 ratio of hydrogen to vinyl functional groups in the mixture of crosslinker (I) and PDMS (II). According to product literature for crosslinking by hydrosilylation (addition), excess crosslinker reduces crosslink density and reduces the performance of the cured adhesive substrate in the form of reduced adhesive strength, crosslink density, adhesion, chemical resistance, and other performance properties. Any amount of crosslinker above the optimum has been found to lead to some degradation of crosslink density and performance.

[0044] In one exemplary embodiment, the first adhesive layer 60 of the adhesive layer 51 that contacts the backing film 50 may comprise a relatively high adhesive strength adhesive base, such as DOWSIL 7657, formulated with an optimized molar ratio of crosslinker (I) to PDMS (II) of 2:1 to maintain sufficient chemical resistance, backing adhesion, and strength. The second adhesive layer 62 of the adhesive layer 51 that is configured to contact the nozzle plate 18 may comprise the same high adhesive strength adhesive base, such as DOWSIL 7657, formulated with a higher molar ratio of crosslinker to PDMS, for example, but not limited to, a molar ratio of 3:1, to reduce the adhesive strength of the second adhesive layer 62 to the nozzle plate 18.

[0045] In another embodiment, the first adhesive layer 60 and the second adhesive layer 62 may comprise different adhesive substrates, and the adhesive strength may be effectively "suppressed" to an acceptable level based on the molar ratio of crosslinker (I) to PDMS (II). In one exemplary embodiment, the first adhesive layer may comprise an adhesive substrate with relatively high adhesive strength, such as DOWSIL 7657, formulated with an optimized molar ratio of crosslinker to PDMS of 2:1, to maintain sufficient chemical resistance. backing adhesion, strength. The second adhesive layer 62 of the adhesive layer 51 configured to contact the nozzle plate 18 may comprise an adhesive substrate with high chemical resistance and relatively high adhesive strength, such as DOWSIL 7667, formulated with a higher molar ratio of crosslinker to PDMS, for example but not limited to a molar ratio of 3:1, to reduce the adhesive strength of the second adhesive layer 62 to the nozzle plate 18 while maintaining some increased chemical resistance.

[0046] As mentioned above, the peel strengths of the first adhesive layer 60 and the second adhesive layer 62 are selected to avoid failures at both the interface between the backing film 50 and the first adhesive layer 60, and the interface between the second adhesive layer 62 and the nozzle plate 18. Thus, the first adhesive layer 60 of the adhesive layer 51 has a peel strength in the range of about 150 N / m to about 500 N / m on a silicon wafer, determined using a 200 millimeter wide sample at a peel speed of 300 mm / min and a 90 degree angle. This range corresponds to an acceptable adhesion strength to avoid failures at the interface between the backing film 50 and the first adhesive layer 60. The second adhesive layer 62 of the adhesive layer 51 has a peel strength in the range of about 25 N / m to about 65 N / m on a silicon wafer, determined using a 200 millimeter wide sample at a peel speed of 300 mm / min and a 90 degree angle. This range corresponds to an acceptable adhesion strength to avoid failure at the interface between the second adhesive layer 62 and the nozzle plate 18. Because the adhesion strength of the first adhesive layer 60 is higher than the adhesion strength of the second adhesive layer 62, the second adhesive layer 62 is unlikely to peel off from the first adhesive layer 60.

[0047] The protective closure tape 12 may be provided via a method using conventional closure tape manufacturing equipment such as a slot die. In one embodiment, the method includes providing a polymeric backing film and preparing two different platinum-cured silicone pressure sensitive adhesive compositions by mixing two main components: (1) a platinum-cured silicone base material and (2) a crosslinker mixture. (1) The platinum-cured silicone base material can be supplied premixed in various Dow Chemical Company DOWSIL products such as DOWSIL 7652, 7657, 7646, 7667, which include an MQ silicone resin, a vinyl-terminated linear siloxane-based polymer such as polydimethylsiloxane or methylphenylsiloxane, diphenylsiloxane or similar compounds, and one or more solvents such as toluene, xylene, or ethylbenzene. (2) The crosslinker mixture includes (a) a platinum siloxane complex catalyst, such as 1,3-diethenyl-1,1,3,3-tetramethyldisiloxane complex (platinum), which is supplied premixed in various Dow Chemical Company products, such as SYL-OFF 4000 catalyst, and (b) a crosslinker including polydimethylsiloxane and polymethylhydrosiloxane, such as crosslinkers supplied premixed in various Dow Chemical Company products, such as SYL-OFF 7678, 7215, and 7660. The components are mixed according to the technical data sheet provided by the manufacturer for each adhesive substrate to produce two different platinum cured silicone adhesive substrate compositions (except where control is desired, where excess crosslinker is used over the optimized molar ratio of crosslinker to PDMS).

[0048] The method then includes coating the backing film 50 with a first adhesive layer 60 of a platinum-cured silicone adhesive substrate composition that has relatively high adhesive strength when cured, such as a composition containing DOWSIL 7657 or 7667. The slot die coater can distribute the adhesive substrate onto the backing film 50 at a desired wet film thickness that corresponds to the amount of solvent present in the adhesive substrate (i.e., the thickness of the layer when the platinum-cured silicone adhesive substrate composition still contains solvent). The thickness of the cured layer can be approximated by multiplying the wet film thickness by the percentage of solids in the substrate composition. For example, a layer containing a substrate composition that is 50% solvent and 50% solids by volume has a dry / cured thickness of 50 microns when applied at a wet film thickness of 100 microns.

[0049] The method further includes coating a second adhesive layer 62 of a platinum cured silicone adhesive substrate composition having relatively low adhesive strength in a cured form onto the first adhesive layer 60, such as a composition including a mixture of DOWSIL 7667 and DOWSIL 7647. The slot die coater can disperse the second adhesive layer 62 onto the first adhesive layer 60 at a desired wet film thickness that corresponds to the amount of solvent present in the adhesive substrate when the composition still contains solvent.

[0050] The desired cured thickness T1 of the first adhesive layer 60 and the desired cured thickness T3 of the second adhesive layer 62 may depend on several factors. In theory, regardless of thickness, the first adhesive layer 60 will increase the adhesion between the adhesive layer 51 and the backing film 50 to a desired degree. If the only objective is a desired adhesion at this interface, a first adhesive layer 60 of about 7 microns thick is acceptable. The lower thickness limit of 7 microns is driven by practical considerations. This is because, among other things, the relatively high adhesion platinum-cured silicone adhesive substrate has a high viscosity, making it difficult to produce an acceptable and uniform coating less than 7 microns thick. In some embodiments, the difficulty due to the high viscosity can be ameliorated by the addition of an additional solvent, such as methyl ethyl ketone, into the substrate composition due to its low boiling point compared to toluene or xylene. However, the platinum-cured silicone substrates that provide relatively high adhesion in the cured form also exhibit relatively high chemical resistance, so if chemical resistance is a goal, first adhesive layer 60 should be relatively thick and should comprise a majority of the total thickness of adhesive layer 51, preferably about 20 microns thick. Additionally, a relatively thick first adhesive layer 60 also minimizes the "squeeze-out" phenomenon in which adhesive layer 51 leaks out from under backing film 50, which is common when using low adhesion, low viscosity platinum-cured silicone adhesive substrates and when closure tape 12 is stored in rolls. If chemical resistance is a priority, second adhesive layer 62 preferably comprises about ⅕ to about ⅓ of the total thickness of adhesive layer 51. In one preferred embodiment which prioritizes chemical resistance and backing film 50 adhesion, the total thickness of adhesive layers 51 is 25 microns, first adhesive layer 60 comprises DOWSIL 7667 adhesive backing and has a thickness of 18 microns, and second adhesive layer 62 comprises DOWSIL 7652 adhesive backing and has a thickness of 7 microns. In the same preferred embodiment, the backing film comprises polyimide and has a thickness T2 of 25 microns.

[0051] However, if the objective is acceptable adhesion between the adhesive layer 51 and the nozzle plate 18 without causing damage, it may be preferable for the second adhesive layer 62 to be thicker than the first adhesive layer 60. Some migration of the low adhesion adhesive substrate to the interface between the first adhesive layer 60 and the backing film 50 can still provide an acceptably strong adhesion between the adhesive layer 51 and the backing film 50. Furthermore, migration and mixing can be controlled and minimized by partially drying or curing the first adhesive layer 60 before coating it with the second adhesive layer 62, or the first adhesive layer 60 can be initially loaded with less solvent. Thus, if acceptable adhesion is the objective, the second adhesive layer 62 should be relatively thick and should constitute a majority of the total thickness of the adhesive layer 51, preferably about 20 microns thick. It is preferred that the first adhesive layer 60 constitutes about 7 microns or more of the total cured thickness of the adhesive layer 51.

[0052] The method further includes one or more curing steps using a multi-zone oven or other suitable equipment. In one variation, the first adhesive layer 60 and the second adhesive layer 62 may be coated on a backing film and cured simultaneously at about 120° C. to 150° C. for about 2 to about 3 minutes. In another variation, the method may include sequentially curing the first adhesive layer 60 and the second adhesive layer 62 in two steps. In the first step, the first adhesive layer 60 may be partially cured at 90° C. for 1 minute, after which the first adhesive layer 60 is coated with the second adhesive layer 62. In the second step, the partially cured first adhesive layer 60 and the second adhesive layer 62 are cured simultaneously at about 120° C. to about 150° C. for about 2 to 3 minutes. Curing evaporates the solvent present in the adhesive substrate and forms the cured thickness described herein.

[0053] Without being bound by theoretical considerations, it is believed that the long, flexible siloxane chains of the second adhesive layer 62 gradually intermingle with the first adhesive layer 60 such that there is no distinct interface between the first adhesive layer 60 and the second adhesive layer 62, but rather there is a gradual transition 64 from the first adhesive layer 60 to the second adhesive layer 62, as shown in Figure 7. In Figure 7, the combined adhesive layer 52 is formed from adhesive layers 62 and 60 of identical thicknesses T3 and T1, respectively, and the intermingling of the two layers 60 and 62 provides a gradual transition 64 between the two layers. As a result, the adhesive layer 52 remains firmly adhered to the backing film 50, but without sacrificing the desired properties (e.g., chemical resistance) of the portion of the adhesive layer 52 that contacts the nozzle plate 18, and without separation of the second adhesive layer 62 from the first adhesive layer 60, the adhesive layer 52 is peeled off cleanly and without damage from the nozzle plate 18 of the ejection head 20.

[0054] The following non-limiting examples represent embodiments of the present invention. Based on the manufacturer's information in the tables below, these formulations can be adjusted to provide adhesives with the strengths indicated.

[0055] [Table 1]

[0056] Adhesive 3 was formulated according to Table 1 and tested for peel strength on bare silicon wafers as described above. The peel strength was 43 N / m. Adhesive 4 was formulated according to Table 1 and tested for peel strength on bare silicon wafers as described above. The peel strength was 24.5 N / m.

[0057] In some embodiments, the protective tape described herein may be preheated prior to filling the cartridge with fluid. It is believed that preheating the protective tape significantly improves the conformability of the protective tape to the cartridge, thereby preventing fluid leakage when exposed to heat during shipping and storage.

[0058] The fluid ejection cartridge 10 described above can be used in a variety of applications, such as inkjet printing applications. The fluid ejection cartridge can also be used in other non-printing applications, particularly applications requiring accurate metering of small amounts of liquid and vapor materials. For example, the ejection cartridges described herein can be used in electronic dispensing devices used in the preparation of cosmetics, paints, or lubricants, medical liquid and vapor ejection, and analytical purposes.

[0059] The foregoing description of the preferred embodiments of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications and variations are possible in light of the above teachings. The embodiments have been chosen and described to best illustrate the principles of the invention and its practical application, thereby enabling those skilled in the art to employ the invention in various embodiments and in various modifications suited to the particular uses contemplated. All such modifications and variations are within the scope of the invention, as determined by the appended claims, when interpreted in accordance with the extent to which they are fairly, legally, and equitably entitled. [Explanation of symbols]

[0060] 10: Fluid ejection cartridge 12, 12a, 12b: protective sealing tape 14: Pull tape 16: Part of protective sealing tape 18: Nozzle plate 20: Discharge head 22: Flexible circuit 24: Electrical contacts 26: First end wall 28: Cover 30: 1st end 32: 2nd end 34: First side wall 38: Second side wall 40: Second end wall 42: Semiconductor substrate 46: Open cell foam 50: Backing film 51, 52: adhesive layer 54: Back side of protective sealing tape 56: Underside of pull tape 58: Front side of protective sealing tape 60: First adhesive layer 62: Second adhesive layer 64: Gradual migration of adhesive layer T1, T2, T3: Thickness

Claims

1. 1. A removable tape configured to seal a nozzle plate of an ejection head attached to a fluid ejection cartridge, comprising: A polymer backing film; a first platinum-cured silicone adhesive layer having a first adhesive strength applied to the polymeric backing film; a second platinum-cured silicone adhesive layer having a second adhesive strength applied to the first platinum-cured silicone adhesive layer; Including, the second platinum-cured silicone adhesive layer is configured to adhere to the nozzle plate on the ejection head of the fluid ejection cartridge; Removable tape.

2. The polymeric backing film is selected from polyethylene terephthalate (PET), polypropylene, polyamide, and polyimide; The removable tape according to claim 1.

3. the polymeric backing film has a thickness in the range of 20 to 30 microns, the first platinum cured silicone adhesive layer has a thickness in the range of 7 to 20 microns on the polymeric backing film, and the second platinum cured silicone adhesive layer has a thickness in the range of 7 to 20 microns on the first platinum cured silicone adhesive layer; The removable tape according to claim 1.

4. The polymeric backing film comprises a corona-treated polymeric backing film. The removable tape according to claim 1.

5. The first adhesive strength is greater than the second adhesive strength; The removable tape according to claim 1.

6. the first platinum-cured silicone adhesive layer and the second platinum-cured silicone adhesive layer comprise different platinum-cured silicone adhesive substrates; The removable tape according to claim 1.

7. The first adhesive strength has a peel strength in the range of 150 to 500 N / m on a dry silicon wafer, and the second adhesive strength has a peel strength in the range of 25 to 65 N / m on a dry silicon wafer. The removable tape according to claim 6.

8. the first platinum-cured silicone adhesive layer and the second platinum-cured silicone adhesive layer comprise the same platinum-cured adhesive substrate; The removable tape according to claim 1.

9. The first adhesive strength has a peel strength in the range of 150 to 500 N / m on a dry silicon wafer, and the second adhesive strength has a peel strength in the range of 25 to 65 N / m on a dry silicon wafer. The removable tape according to claim 8.

10. 1. A method for making an improved removable tape configured to seal a nozzle plate of an ejection head attached to a fluid ejection cartridge, comprising: Providing a polymeric backing film; combining a crosslinker mixture comprising polydimethylsiloxane and polymethylhydrosiloxane with a first platinum-cured silicone adhesive substrate to provide a first platinum-cured silicone adhesive, and combining the crosslinker mixture with a second platinum-cured silicone adhesive substrate to provide a second platinum-cured silicone adhesive; applying a first layer of the first platinum-cured silicone adhesive having a first adhesive strength to the polymeric backing film; applying a second layer of the second platinum-cured silicone adhesive having a second adhesive strength to the first layer; curing the first layer and the second layer; Including, method.

11. sequentially curing said first layer and said second layer. The method of claim 10.

12. said curing comprising partially curing said first layer at a temperature of at least 90° C. for 1 minute, and then curing said first layer and said second layer at a temperature of 120° C. to 150° C. for 2 to 3 minutes; The method of claim 11.

13. simultaneously curing said first layer and said second layer. The method of claim 10.

14. said curing comprising curing said first layer and said second layer at a temperature of 120° C. to 150° C. for 2 minutes to 3 minutes; The method of claim 13.

15. the first platinum-cured silicone adhesive and the second platinum-cured silicone adhesive comprise different platinum-cured adhesive substrates; The method of claim 10.

16. the first platinum-cured silicone adhesive and the second platinum-cured silicone adhesive comprise the same platinum-cured adhesive substrate; The method of claim 10.

17. mixing a first amount of the crosslinker mixture with the first platinum-cured silicone adhesive base material and mixing a second amount of the crosslinker mixture with the second platinum-cured silicone adhesive base material. Further comprising: further, said second amount of crosslinker mixture is greater than said first amount of crosslinker mixture; The method of claim 15.

18. 1. A method for improving sealing of a nozzle plate of an ejection head mounted in a fluid ejection cartridge, comprising: providing a cartridge body having a cover closing a first end, a dispensing head on a second end opposite said first end, and a sidewall attached to said first end and said second end between said first end and said second end; attaching a removable tape to the nozzle plate and one of the side walls of the ejection head; Including, The removable tape includes a backing film and a modified platinum-cured silicone adhesive layer having a first adhesive strength adjacent to the backing film and a second adhesive strength adjacent to the nozzle plate that is less than the first adhesive strength. method.

19. The first adhesive strength has a peel strength in the range of 150 to 500 N / m on a dry silicon wafer, and the second adhesive strength has a peel strength in the range of 25 to 65 N / m on a dry silicon wafer.

20. The method of claim 18.

20. said modified platinum cured silicone adhesive layer having a thickness on said backing film in the range of 20 to 30 microns; 20. The method of claim 18.

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