Epoxy-based UV-VIS curable sealant composition

Abstract

% of at least one cationic photoinitiator; e) 0-30 wt. % of at least one cationically curable cyclic compound different from a and b; f) 0-30 wt. % of at least one further additive different from a-e selected from the group consisting of photosensitizers, surfactants, adhesion promoters, and mixtures thereof; the UV-VIS curable sealant composition has a viscosity of about 60,000 mPas to about 120,000 mPas at 25° C.; the weight percentages are based on the total weight of the UV-VIS curable sealant composition.

Description

Detailed Description of the Invention

[0001] [Field of the Invention] This invention relates to the technical field of UV-VIS curable sealant compositions useful for protecting exposed electrical contacts in inkjet printheads, their uses, and methods for manufacturing inkjet printhead assemblies containing the UV-VIS curable sealant compositions.

[0002] [Background of the invention] A typical inkjet printhead cartridge, as described in EP 1896262 (see Figure 1) or Figure 1, is made up of a printhead ejection assembly consisting of a printhead chip bonded to a flexible printed circuit. The printhead silicon chip, also known as a silicon ejector group, houses the electrical and hydraulic components to direct ink to various ejection sites and apply electrical current as needed to generate ink droplets for printing. A nozzle plate is attached to the top of the chip and provides the ink ejection nozzles. The entire ejection assembly is in turn bonded to a cartridge containing an ink reservoir sealed by a lid. A suitable ink slot is located in the cartridge body, allowing ink to reach the printhead chip and the microfluidic circuitry either through slots machined into the chip or from the end of the chip, depending on the printhead layout.

[0003] Silicon chips and flexible circuits are connected to each other through electrical contacts or leads. UV-VIS curable sealant compositions can be used to cover these exposed areas (see Figure 2). The sealant must accurately surround all uncovered areas near the bonding area, i.e., chip pads and leads. To be effective, the sealant must ensure good contact with the various materials used in printhead assembly, such as conductors made of various metals, silicon and silicon compounds, polymers, and adhesives. It must surround all uncovered areas and completely fill any gaps or depressions in the surface features. At the same time, the sealant shape must remain stable, and its surface should remain confined to the dispensed area without spreading to surrounding areas. In other words, the sealant should retain its shape after dispensing, and to achieve this, it must have the appropriate rheology. In this way, the UV-VIS curable sealant composition does not cover critical areas near the nozzle, maintains substantial thickness and rigidity, and allows for rapid movement of the assembly between the dispensing station and the UV-VIS curing station without substantially losing its dispensed pre-cured shape (see Figure 3).

[0004] During normal operation of the printhead in an ink jet printer, the sealant comes into contact with the ink dispensed from the nozzles, and therefore there is a constant risk that this routine exposure will compromise the sealant composition and cause it to lose its integrity over time.

[0005]

[0005] If the ink is solvent-based, the sealant will be subjected to strong chemical exposure in the solvent environment over the life of the printhead, which can lead to the phenomenon of "swelling" of the sealant and the loss of integrity of the sealant material.

[0006] Furthermore, the long-term presence or buildup of ink on the front end of a printhead, not only for solvent-based inks but also for water-based inks, can be detrimental to the electrical integrity of the printhead. Ink accumulated on the front end of a printhead due to printing operations can remain on the front end of the printhead for weeks to months without being cleaned. This residue can induce delamination of the UV-VIS curable sealant composition and / or corrosion of electrical contacts, ultimately resulting in failure of the printhead assembly. Periodic replacement will therefore be required, resulting in additional costs to the user.

[0007]

[0007] Therefore, there is a need to provide a UV-VIS curable sealant composition suitable for protecting exposed electrical contacts on inkjet printheads, which ensures high adhesion to a variety of surfaces, provides good protection for ink-exposed electrical components, and overcomes the various problems discussed herein. In particular, the sealant composition should have good thixotropy and suitable viscosity to exhibit the desired dispensability and form stability with air pressure or vortex tube systems. The composition should be compatible with manufacturing processes and exhibit high chemical resistance, adhesion, and good flexibility to provide a durable sealing means for electrical components, especially after the ink has been on the front end of the printhead for an extended period of time.

[0008] [Summary of the Invention] In a first aspect, the present invention relates to a UV-VIS curable sealant composition, the composition comprising: a) 25 to 40 wt. % of at least one aromatic epoxide monomer or aromatic epoxide oligomer or a mixture thereof; b) 4 to 20 wt % of at least one epoxidized polyene; c) 20-35 wt% of at least one organic or inorganic filler or mixture thereof; d) 0.1 to 10 wt % of at least one cationic photoinitiator; e) 0 to 30 wt. % of at least one cationically curable cyclic compound different from a) and b); f) 0.05-3 wt% nonionic surfactant; g) 0 to 30 wt. % of at least one further additive different from components a) to f) selected from the group consisting of photosensitizers, adhesion promoters and mixtures thereof Including, The UV-VIS curable sealant composition has a viscosity of about 60,000 mPas to about 120,000 mPas at 25°C; The weight percentages are based on the total weight of the UV-VIS curable sealant composition.

[0009] In a second aspect, the present invention relates to an inkjet printhead comprising, in an at least partially cured state, the UV-VIS curable sealant composition described herein.

[0010] In a second aspect, the present invention relates to a method for sealing electrical contacts on an inkjet printhead, the method comprising: a) providing a UV-VIS curable sealant composition described herein; b) providing an assembly including a flexible circuit and a silicon chip; c) dispensing a UV-VIS curable sealant composition onto the electrical contacts connecting the silicon chip to the flexible circuit; d) curing or at least partially curing the UV-VIS curable sealant composition using a UV-VIS light source; Includes.

[0011] In a final aspect, the present invention relates to the use of the UV-VIS curable sealant composition described herein for manufacturing an inkjet printhead as described herein.

[0012] Surprisingly, it has been discovered that the UV-VIS curable sealant compositions described herein provide at least the following advantages: Chemical resistance or stability to various inks, especially solvent-based inks, after curing; Good adhesion and wetting to various substrates of inkjet printheads such as Kapton, gold, silicon (carbide) or nickel; Good distribution by air pressure or vortex system; Good thixotropy and visibility after dispensing with optical detector systems; Fast and efficient curing temperatures and performance compatible with high speed manufacturing of printhead systems.

[0013] [Brief description of drawing / diagram]

[0013] Figure 1 is a schematic diagram of an inkjet printhead cartridge (1). The cartridge (1) houses a printhead chip (2) with a nozzle plate (3) on its surface. Line BB in the figure corresponds to the direction of relative movement between the print medium and the printhead during printing. Ink droplets are ejected from the nozzles by electrical signals sent from the printer to the printhead chip; a flexible printed circuit (4) is used for this purpose. Polyimide is often used for flexible circuit substrates. A window is created in the surface of the flexible printed circuit to allow the printhead chip to protrude, so that the flexible printed circuit surrounds the chip. Conductive metal traces on the flexible printed circuit protrude from the edge of the window and make electrical contact with the chip as leads. Contact areas (5) are provided on the other side of the flexible circuit for electrical communication with the printer. The electrical connection between the leads and the chip is secured by a suitable bonding process, such as tape automated bonding (TAB). To enable the bonding process, a number of bonding pads are provided near the periphery of the chip, with the leads housed on their surfaces, so that the pad surfaces must be freely accessible by the bonding tool without being covered by any layer until the bonding process is complete. Typically, though not in all cases, the pads are located near the short sides of the printhead chip.

[0014]

[0014] Figure 2 shows a cross-sectional view of a printhead chip (2) and flexible circuit with a cured or at least partially cured UV-VIS curable sealant composition (16). The view is taken perpendicular to line BB. The chip (2) is a silicon substrate having conductive, resistive, dielectric, and protective layers on its surface. It is covered with a patterned barrier layer (6) on which a hydraulic printhead circuit with ejection chambers (7) is mounted. The barrier layer, typically a polymer, is covered by a nozzle plate (3), the nozzles of which can eject ink droplets (8). Bonding pads (9) are located near the chip side and bonded to the pad surface, housing leads (10) protruding from the flexible printed circuit (4). The leads are extensions of the conductive traces (11) on the flexible printed circuit. A suitable adhesive layer (12) secures the flexible printed circuit to the cartridge body. The adhesive layer also functions as a protective insulating agent, preventing the conductive traces (11) from mechanically or electrically contacting any part or material that could cause damage or shorts. To allow contact between the conductors during the bonding process, the pad surfaces must be uncovered. For this reason, during patterning, the barrier layer in the pad area is removed, leaving only the backside of the pad (13), preventing mechanical contact between the substrate and the leads. During printing, the front end of the chip is exposed to ink contact and sometimes even wiping with a suitable blade. Therefore, after the bonding step is complete, the pad area and leads must be covered with an encapsulating UV-VIS curable sealant material (16) to protect the electrical connection, avoid mechanical damage, shorts, and provide chemical resistance or electrical insulation.

[0015] 3 illustrates the process steps of dispensing a UV-VIS curable sealant composition using a dispensing station (18) (left) and curing or at least partially curing the composition using a curing station (20) (right). After bonding, the chip and flexible printed circuit assembly (17) is transferred to the dispensing station (18), where a quantity of still-uncured UV-VIS curable sealant composition (19) is delivered to each area to be protected. The assembly (17) with the dispensed UV-VIS curable sealant is quickly moved to the curing station (20), where UV-VIS lamps (21) cure the UV-VIS curable sealant composition. [Brief explanation of the drawings]

[0016] [Figure 1]Figure 1 is a schematic diagram of an inkjet printhead cartridge (1). The cartridge (1) houses a printhead chip (2) with a nozzle plate (3) on its surface. Line BB in the diagram corresponds to the direction of relative motion between the print medium and the printhead during printing. Ink droplets are ejected from the nozzles by electrical signals sent from the printer to the printhead chip; a flexible printed circuit (4) is used for this purpose. Polyimide is often used for flexible circuit substrates. A window is created in the surface of the flexible printed circuit to allow the printhead chip to protrude, so that the flexible printed circuit surrounds the chip. Conductive metal traces on the flexible printed circuit protrude from the edge of the window and make electrical contact with the chip as leads. Contact areas (5) are provided on the other side of the flexible circuit for electrical communication with the printer. The electrical connection between the leads and the chip is secured by a suitable bonding process, such as tape automated bonding (TAB). To enable the bonding process, a number of bonding pads are provided near the periphery of the chip, with the leads housed on their surfaces, so that the pad surfaces must be freely accessible by the bonding tool without being covered by any layer until the bonding process is complete. Typically, though not in all cases, the pads are located near the short sides of the printhead chip. [Figure 2]Figure 2 shows a cross-sectional view of a printhead chip (2) and flexible circuit with a cured or at least partially cured UV-VIS curable sealant composition (16). The view is perpendicular to line BB. The chip (2) is a silicon substrate having conductive, resistive, dielectric, and protective layers on its surface. It is covered with a patterned barrier layer (6) on which a hydraulic printhead circuit with ejection chambers (7) is mounted. The barrier layer, typically a polymer, is covered by a nozzle plate (3), the nozzles of which can eject ink droplets (8). Bonding pads (9) are located near the chip side and bonded to the pad surface, housing leads (10) protruding from the flexible printed circuit (4). The leads are extensions of the conductive traces (11) on the flexible printed circuit. A suitable adhesive layer (12) secures the flexible printed circuit to the cartridge body. The adhesive layer also functions as an insulating protectant, preventing mechanical or electrical contact between the conductive traces (11) and parts or materials that could cause damage or short circuits. To allow contact between the conductors during the bonding process, the pad surfaces must be uncovered. For this reason, during patterning, the barrier layer in the pad area is removed, leaving only the backside of the pad (13) to prevent mechanical contact between the substrate and the leads. During printing, the front end of the chip is exposed to ink contact and sometimes even wiping action with a suitable blade. Therefore, once the bonding step is complete, the pad area and leads must be covered with an encapsulating UV-VIS curable sealant material (16) to protect the electrical connection, avoid mechanical damage, short circuits, and provide chemical resistance or electrical insulation. [Figure 3]3 illustrates the process steps of dispensing a UV-VIS curable sealant composition using a dispensing station (18) (left) and curing or at least partially curing the composition using a curing station (20) (right). After bonding, the chip and flexible printed circuit assembly (17) is transferred to the dispensing station (18), where a quantity of still-uncured UV-VIS curable sealant composition (19) is delivered to each area to be protected. The assembly (17) with the dispensed UV-VIS curable sealant is quickly moved to the curing station (20), where UV-VIS lamps (21) cure the UV-VIS curable sealant composition.

[0017] [Detailed description] definition The following definitions are used to interpret the meaning of terms discussed herein and recited in the claims.

[0018] As used herein, the article "a" denotes one and more than one and does not necessarily limit the referenced noun to the singular.

[0019]

[0018] As used herein, the term "about" means that the amount or value in question may be the indicated value or another similar value. These expressions are intended to convey that a similar value within ±5% of the indicated value will promote the same results or effects according to the present disclosure.

[0020]

[0019] As used herein, the term "UV-VIS" is intended to mean radiation having wavelength components in the UV-VIS portion of the electromagnetic spectrum, typically between 200 nm and 420 nm.

[0021] As used herein, the term "at least one" is meant to define one or more, for example, 1 or 2 or 3.

[0022] As used herein, the term "and / or" means that all or just one of the elements of the group may be present. For example, "A and / or B" means "just A, just B, or both A and B." In the case of "just A," the term also encompasses the possibility that B is absent, i.e., "only A and no B."

[0023]

[0022] As used herein, the term "comprising" is intended to be non-exclusive and non-limiting. Thus, for example, a UV-VIS-curable sealant composition comprising compound A may contain other compounds in addition to A. However, the term "comprising" also encompasses the more restrictive meanings of "consisting essentially of" and "consisting of," as specific embodiments thereof. For example, a "UV-VIS-curable sealant composition comprising A, B, and optionally C" may consist (essentially) of A and B, or consist (essentially) of A, B, and C.

[0024]

[0023] When this specification refers to "preferred" embodiments / features, combinations of these "preferred" embodiments / features are also deemed to be disclosed, as long as this combination of "preferred" embodiments / features makes technical sense.

[0025] The term "wt %" refers to the amount of the stated component relative to the total weight of the UV-VIS curable sealant composition.

[0026] The UV-VIS curable sealant compositions described herein comprise: a) 20 to 50 wt % of at least one aromatic epoxide monomer or aromatic epoxide oligomer or a mixture thereof; b) 4 to 20 wt % of at least one epoxidized polyene; c) 15 to 35 wt. % of at least one organic or inorganic filler or mixture thereof; d) 0.1 to 10 wt % of at least one cationic photoinitiator; e) 0 to 30 wt. % of at least one cationically curable cyclic compound different from a) and b); f) 0 to 30 wt. % of at least one further additive different from components a) to e) selected from the group consisting of photosensitizers, surfactants, adhesion promoters and mixtures thereof Including, The UV-VIS curable sealant composition has a viscosity of 60,000 mPas to about 120,000 mPas at 25°C, The weight percentages are based on the total weight of the UV-VIS curable sealant composition.

[0027] In some embodiments, the UV-VIS curable sealant compositions described herein comprise: a) 25 to 40 wt. % of at least one aromatic epoxide monomer or aromatic epoxide oligomer or a mixture thereof; b) 5 to 15 wt % of at least one epoxidized polyene; c) 20-35 wt% of at least one organic or inorganic filler or mixture thereof; d) 1 to 5 wt % of at least one cationic photoinitiator; e) 0 to 30 wt. % of at least one cationically curable cyclic compound different from a) and b); f) 0 to 30 wt. % of at least one further additive different from components a) to e) selected from the group consisting of photosensitizers, surfactants, adhesion promoters and mixtures thereof; Includes.

[0028] The UV-VIS curable sealant compositions described herein comprise at least one aromatic epoxide monomer or aromatic epoxide oligomer or mixtures thereof (a). As used herein, aromatic epoxide monomer or aromatic epoxide oligomer refers to a component containing reactive or curable epoxide group(s) and an aromatic moiety. The at least one aromatic epoxide monomer and aromatic epoxide oligomer can independently have an epoxide functionality (number of epoxide groups per molecule) of greater than 2 to about 8; about 2.1 to about 5; about 2.3 to about 4; about 2.5 to about 3.5; or about 2. The aromatic epoxide monomer or oligomer can be present in the composition in an amount of about 20 to about 50 wt%, preferably about 30 to about 40 wt%, even more preferably about 35 to about 40 wt%, or even about 25 to about 40 wt%.

[0029]

[0028] The aromatic epoxide monomers or oligomers may be derived from mononuclear phenols such as, for example, resorcinol or hydroquinone, or may be based on polycyclic phenols such as, for example, bis-(4-hydroxyphenyl)methane (bisphenol F), 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), or may be based on condensations obtained under acidic conditions between phenol or cresol and formaldehyde, commonly known as novolaks, especially phenol novolaks and cresol novolaks.

[0030] Suitable commercially available aromatic epoxide monomers or oligomers include, but are not limited to, the ARALDITE® GY series of bisphenol A type epoxy liquid resins, the ARALDITE® CT and GT series of bisphenol A type epoxy solid resins, the ARALDITE® GY and PY series of bisphenol F type epoxy liquids, the ARALDITE® ECN series of epoxy cresol novolacs, the ARALDITE® EPN series of epoxy phenol novolacs, and the DEN series of epoxy novolac resins from PalmerHolland.

[0031] In a preferred embodiment, the aromatic epoxide monomer or aromatic epoxide oligomer is an epoxy novolac resin.

[0032] The UV-VIS curable sealant composition comprises at least one cationic photoinitiator (d) described herein in an amount of about 0.1 to about 10 wt %, preferably about 3 to about 12 wt %, more preferably about 4 to about 10 wt %, and even more preferably about 1 to about 5 wt %, wherein the at least one cationic photoinitiator (d) is an onium salt described herein. The onium salt described herein is preferably selected from the group consisting of (di)azonium salts, oxonium salts, (diaryl)iodonium salts, sulfonium salts, and mixtures thereof, more preferably selected from the group consisting of oxonium salts, iodonium salts, sulfonium salts, and mixtures thereof, and even more preferably selected from the group consisting of iodonium salts, sulfonium salts, and mixtures thereof.

[0033] The iodonium salts described herein have a cationic portion and an anionic portion, the anionic portion preferably being BF4 - , B(C6F5)4 - , PF6 - , AsF6 - , SbF6 - or CF3SO3 - , more preferably SbF6- or PF6 - wherein the cationic moiety is preferably an aromatic iodonium ion, more preferably an iodonium ion containing two aryl groups, which may be independently substituted with one or more alkyl groups (e.g., methyl, ethyl, isobutyl, tertiary butyl, etc.), one or more alkoxy groups, one or more nitro groups, one or more halogen-containing groups, one or more hydroxy groups, or combinations thereof. Examples of iodonium salts particularly suitable for the present disclosure are commercially available from IGM Resins under the names Omnicat 250 and 440 and from Lambson under the name SpeedCure 938.

[0034] The sulfonium salts described herein have a cationic portion and an anionic portion, the anionic portion preferably being BF4 - , B(C6F5)4 - , PF6 - (PF 6-m (C n F 2n-1 ) m ) - [wherein m is an integer of 1 to 5, and n is an integer of 1 to 4], AsF6 - , SbF6 - , CF3SO3 - , perfluoroalkyl sulfonates or pentafluorohydroxyantimonates, more preferably SbF6 - or PF6 - wherein the cationic moiety is preferably an aromatic sulfonium ion, more preferably a sulfonium ion containing two or more aryl groups, wherein the two or more aryl groups are optionally independently substituted with one or more alkyl groups (e.g., methyl, ethyl, isobutyl, tertiary butyl, etc.), one or more alkoxy groups, one or more aryloxy groups, one or more halogen-containing groups, one or more hydroxy groups, or a combination thereof.

[0035] Suitable examples of sulfonium ions containing two or more aryl groups include, but are not limited to, triarylsulfonium ion, diphenyl[4-(phenylthio)phenyl]sulfonium ion, bis[4-(diphenylsulfonio)phenyl]sulfonium ion, triphenylsulfonium ion, and tris[4-(4-acetylphenyl)sulfanylphenyl]sulfonium ion.

[0036] In a preferred embodiment, the at least one cationic photoinitiator d) is selected from the group consisting of triphenylsulfonium salts, diazonium salts, diaryliodonium salts, ferrocenium salts, metallocene compounds and mixtures thereof.

[0037] Suitable commercially available cationic photoinitiators d) include, but are not limited to, Irgacure PAG290 (BASF), diphenyliodonium hexafluorophosphate (Sigma-Aldrich), diphenyliodonium hexafluoroantimonate (Sigma-Aldrich), triarylsulfonium hexafluorophosphate salts (Sigma Aldrich) and / or triphenylsulfonium triflate (Sigma-Aldrich), aromatic iodonium salts and aromatic sulfonium salts such as, for example, triarylsulfonium hexafluorophosphate (CYRACURE® UVI-6992, Dow Chemical Company), triarylsulfonium hexafluoroantimonate (CYRACURE® UVI-6976, Dow Chemical Company) and arylsulfonium hexafluorophosphate (ESACURE 1064, Lamberti). Arylsulfonium hexafluorophosphate (ESACURE 1064, Lamberti), bis-(4-dodecylphenyl)iodonium hexafluoroantimonate in glycidyl ether (SpeedCure 937), bis-(4-t-butylphenyl)-iodonium hexafluorophosphate (SpeedCure 938), bis-(4-t-butylphenyl)-iodonium hexafluorophosphate (SpeedCure 939), (sulfanediyldibenzene-4,1-diyl)bis(diphenylsulfonium) bis(hexafluoroantimonate) in propylene carbonate (SpeedCure 976), (sulfanediyldibenzene-4,1-diyl)bis(diphenylsulfonium) bis(hexafluoroantimonate) in propylene carbonate (SpeedCure 992) Arkema, diphenyl[(phenylthio)phenyl]sulfonium (PAG-20001), mixed triarylsulfonium hexafluoroantimonate salts PAG-20002 or PAG-21608 Aalchem.

[0038]

[0037] Other examples of useful photoinitiators can be found in standard textbooks such as "Chemistry & Technology of UV & EB Formulation for Coatings, Inks & Paints", Vol. 3, "Photoinitiators for Free Radical Cationic and Anionic Polymerization", 2nd Edition, by JV Crivello & K. Dietliker, edited by G. Bradley, 1998, published by John Wiley & Sons in association with SITA Technology Limited.

[0039] The UV-VIS curable sealant composition comprises at least one epoxidized polyene described herein in an amount of about 4 to about 20 wt %, preferably about 5 to about 15 wt %. As used herein, the expression epoxidized polyene b) refers to epoxidized poly-1,3-dienes such as polybutadiene and polyisoprene, or epoxidized copolymers having butadiene or isoprene moieties. Examples of epoxidized polyenes include epoxidized polybutadiene, epoxidized polyisoprene, epoxidized co-polyenes having butadiene moieties, and epoxidized co-polyenes having isoprene moieties. The number average molecular weight (M n ) is preferably 500 to 50,000, more preferably 1,000 to 5,000. If the molecular weight exceeds 50,000, the epoxidized product may not be liquefied, resulting in reduced work efficiency, while if it is less than 500, the epoxidized product may not function as a flexibilizer as desired. The number average molecular weight can be determined by a suitable gel permeation chromatography (GPC) method known to those skilled in the art.

[0040] In a preferred embodiment, the epoxidized polyene is an epoxidized polybutadiene.

[0041]

[0040] The epoxidized polyenes b) described herein have epoxy groups in the molecule and may also have hydroxyl groups. The hydroxyl groups may be derived from the polyene or may be formed during the epoxidation of the polyene. Among the epoxidized polyenes disclosed herein, hydroxyl-terminated epoxidized polybutadiene has superior compatibility with other epoxy resins compared to hydrogen-terminated epoxidized polybutadiene when they have the same oxirane oxygen content.

[0042] Suitable commercially available epoxidized polyenes include, but are not limited to, EPOLEAD PB3600 (Daicel), an epoxy-functionalized and hydroxy-terminated polybutadiene (CAS: 129288-65-9, Sigma Aldrich).

[0043] The UV-VIS curable sealant composition may also include an epoxy-containing component, which may be an aliphatic or cycloaliphatic epoxide or a mixture thereof. If present, the epoxy-containing compound is different from components a) and b).

[0044] The cycloaliphatic epoxides described herein can be difunctional or polyfunctional. Preferably, the cycloaliphatic epoxides described may independently contain at least one cyclohexane group and at least two epoxide groups. Preferred cycloaliphatic epoxides contain two or more cyclohexane epoxide groups and have the structural formula (I): [ka] wherein X is selected from a single bond and a divalent group containing one or more atoms.

[0045] According to one embodiment, X is a divalent hydrocarbon group that is a straight or branched chain alkylene group containing 1 to 18 carbon atoms, examples of which include, but are not limited to, methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene.

[0046] According to one embodiment, X is a divalent alicyclic hydrocarbon group or a cycloalkydene group, such as 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, and cyclohexylidene.

[0047] According to one embodiment, X is a divalent group containing one or more oxygen-containing linking groups, which are -CO-, -O-CO-O-, -COO-, and -O-. According to one embodiment, preferred epoxy derivatives containing two or more cyclohexane oxide groups and having structural formula (I) [wherein X is a divalent group containing one or more oxygen-containing linking groups, which are -CO-, -O-CO-O-, -COO-, and -O-] have structural formula (II), (III), or (IV). [ka] This corresponds to 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, where R1-R9 are independently hydrogen or a straight-chain or branched alkyl group containing 1 to 10 carbon atoms, preferably 1 to 3 carbon atoms (such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, hexyl, octyl, and decyl). Preferred cycloaliphatic epoxides having structural formula (II) are 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methyl-cyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, 3,4-epoxy-2-methyl-cyclohexylmethyl-3,4-epoxy-2-methyl-cyclohexanecarboxylate, and 3,4-epoxy-4-methyl-cyclohexylmethyl-3,4-epoxy-4-methylcyclohexanecarboxylate. [ka] It corresponds to a cycloaliphatic diepoxide ester of a dicarboxylic acid, wherein R1-R9 are independently hydrogen or a straight or branched alkyl group containing from 1 to 10 carbon atoms (such as methyl, ethyl, n-propyl, isopropyl, butyl, hexyl, octyl, and decyl), preferably containing from 1 to 3 carbon atoms, and wherein A is a valence bond or an alkylene group (such as, for example, trimethylene, tetramethylene, hexamethylene, and 2-ethylhexylene), and an alkylene group (such as, for example, 1,4-cyclohexane, 1,3-cyclohexane, and 1,2-cyclohexane). cycloaliphatic diepoxide esters of dicarboxylic acids having structural formula (III) are preferably bis(3,4-epoxycyclohexylmethyl) adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, bis(3,4-epoxycyclohexylmethyl) oxalate, bis(3,4-epoxycyclohexylmethyl) pimelate, and bis(3,4-epoxycyclohexylmethyl) sebacate. [ka] wherein R1 to R9 are independently hydrogen or a linear or branched hydrocarbon group containing 1 to 3 carbon atoms; a preferred example of an alicyclic diepoxide having structural formula (IV) is 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meta-dioxane.

[0048] According to one embodiment, the cycloaliphatic epoxides described herein have structural formula (V) or (VI): [ka]

[0049] The cycloaliphatic epoxides described herein may be hydroxy-modified or (meth)acrylate-modified. Examples are commercially available under the names Cyclomer A400 (CAS: 64630-63-3) and Cyclomer M100 (CAS: 82428-30-6) from Daicel Corporation, or TTA15 and TTA16 from TetraChem / Jiangsu, Celloxide 2021P from Daicel Corporation, CYRACURE™ 6110UVR, CYRACURE™ 6105UVR from Dow Chemical, 3,4 epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate from Sigma Aldrich, or ACHWL CER4221 from PHLEX TEK, 7-oxabicyclo[4.1.0]hept-3-ylmethyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate (UviCure S105) from Arkema.

[0050] The UV-VIS curable sealant composition includes at least one filler c). The filler can be an organic filler, an inorganic filler, or a mixture thereof. The at least one filler is preferably present in an amount of about 15 to about 35 wt %, more preferably about 20 to about 25 wt %. In a preferred embodiment, the filler has a refractive index at 400 nm of about 1.2 to about 1.8, preferably about 1.3 to about 1.6, and / or a particle size of about 5 to about 15 μm, preferably about 5 to about 9 μm. When the refractive index of the filler is within the range specified above, the UV-VIS curable sealant composition has suitable transparency properties to the UV-VIS radiation used in the curing process.

[0051]

[0050] The refractive index of the at least one filler c) can be measured using ISO 489:2022 and the particle size can be determined by laser diffraction using ISO 13320:2020. Further refractive indices of various materials are also available from Refractive Index Information (refractiveindex.info).

[0052]

[0051] The inorganic filler is preferably selected from the group consisting of carbon fiber, talc, mica (muscovite), wollastonite, calcined clay, china clay, kaolin, carbonates (e.g., calcium carbonate, sodium aluminum carbonate), silicates (e.g., magnesium silicate, aluminum silicate), sulfates (e.g., magnesium sulfate, barium sulfate), titanates (e.g., potassium titanate), alumina hydrate, silica, fumed silica, montmorillonite, graphite, anatase, rutile, bentonite, vermiculite, zinc white, zinc sulfide, wood flour, quartz flour, natural fibers, synthetic fibers, glass, and mixtures thereof. Preferred inorganic fillers are selected from the group consisting of glass, carbonates, talc, and mixtures thereof. A particularly preferred inorganic filler is talc.

[0053] Preferably, filler c) is an organic filler. The organic filler can be selected from the group consisting of acrylic resins made from at least acrylic or methacrylic esters, their copolymers with styrene (i.e., styrene-acrylic resins), modified rosin resins, terpene-based resins, modified terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral, polyacrylic polyols, polyvinyl alcohol, polyurethanes, hydrogenated petroleum resins, and mixtures thereof. Advantageously, polymeric acrylic resins based on PMMA (polymethyl methacrylate), PMMA-DEGDA (polymethyl methacrylate diethylene glycol diacrylate), PBMA (polybutyl methacrylate), and PiBMA (polyisobutyl methacrylate) are preferred. Other suitable resins include crosslinked poly(styrene-co-divinylbenzene) or poly(4-vinylpyridine-co-ethylvinylbenzene). In a preferred embodiment, the organic polymeric filler has a particle size of ≦10 μm. When the filler has a particle size as described herein, the compatibility of the filler in the UV-VIS curable sealant composition is improved, and after dispensing, the composition maintains high homogeneity and shape or form stability. The acrylic resin provides the desired rheological properties over time in terms of chemical robustness and / or chemical stability without inducing weaknesses in the composition.

[0054]

[0053] Unlike a) and b), the at least one cationically curable cyclic compound e) that can be used in the UV-VIS curable sealant composition described herein includes oxetanes, oxolanes, cyclic acetals, anhydrides, cyclic lactones, thiiranes, and thiotanes. Typical oxolane compounds include tetrahydrofuran and 2,3-dimethyl-tetrahydrofuran. Typical cyclic acetal compounds include trioxane, 1,3-dioxalane, and 1,3,6-trioxanecyclooctane. Typical cyclic lactone compounds include β-propiolactone and ε-caprolactone. Typical anhydrides include phthalic anhydride and terephthalic anhydride and their hydroxy-containing derivatives. Typical thiirane compounds include ethylene sulfide, 1,2-propylene sulfide, and thioepichlorohydrin. Typical thiotane compounds include 1,3-propylene sulfide and 3,3-dimethylthiotane. The cationically curable cyclic compound e) may be present in the UV-VIS curable sealant composition in an amount of from about 0 to about 30 wt %, preferably from about 15 to about 30 wt %, and even more preferably from about 20 to about 25 wt %.

[0055] According to preferred embodiments, the UV-VIS curable sealant compositions described herein may include one or more oxetane compounds or compounds having oxetane functionality. In embodiments where the UV-VIS curable sealant compositions described herein include one or more oxetanes, the one or more oxetanes are present in an amount of about 30 wt % or less, preferably about 5 wt % or more and about 25 wt % or less.

[0056]

[0055] Preferred examples of oxetanes include trimethylene oxide, 3,3-dimethyloxetane, trimethylolpropaneoxetane, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane, 3,3-dicyclomethyloxetane, 3-ethyl-3-phenoxymethyloxetane, bis([1-ethyl(3-oxetanyl)]methyl)ether, 1,4-bis[3-ethyl(3-oxetanylmethoxy)methyl]benzene, 3,3-dimethyl-2(p-methoxy-phenyl)-oxetane, 3-ethyl-[(tri-ethoxysilylpropoxy)methyl]oxetane, 4,4-bis(3-ethyl-3-oxetanyl)methoxymethyl]biphenyl and 3,3-dimethyl-2(p-methoxy-phenyl)oxetane. One or more of the oxetanes described herein may be hydroxy-modified or (meth)acrylate-modified.

[0057] Suitable examples of commercially available oxetanes include, but are not limited to, OXT221 (Toa Gosei Chemical), 3-ethyl-3-oxetanemethanol (Sigma-Aldrich), 3,3-dimethyloxetane (Sigma-Aldrich), and / or 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane (OXT212) (Toa Gosei Chemical).

[0058] The UV-VIS curable sealant composition may comprise at least one further additive selected from the group consisting of photosensitizers, surfactants, adhesion promoters, and mixtures thereof; Additive f) is different from components a) to e), and the amount of said at least one further additive can be from about 0 to about 30 wt %, preferably from about 2 to about 20 wt %, and even more preferably from about 5 to about 15 wt %.

[0059] In one embodiment, the at least one additional additive is a photosensitizer, and the UV-VIS curable sealant composition may include one or more of the photosensitizers. The photosensitizer is activated by one or more of the wavelengths emitted by the UV-VIS light source to reach an excited state. The excited photosensitizer then transfers energy to at least one cationic photoinitiator, which in turn initiates the polymerization process. When present, the one or more photosensitizers are preferably present in an amount of about 0.1 to about 10 wt %, more preferably about 0.1 to about 5 wt %, and even more preferably about 0.2 to about 1 wt %.

[0060] Commercially available photosensitizers include, but are not limited to, thioxanthone derivatives, anthracene derivatives (such as 9,10-diethoxyanthracene sold as ANTHRACURE® UVS-1101 and 9,10-dibutyloxyanthracene sold as ANTHRACURE® UVS-1331, both sold by Kawasaki Chemical Industries, Ltd.), and titanocene derivatives (such as Irgacure® 784 sold by BASF). Other suitable photosensitizers include, but are not limited to, isopropyl-thioxanthone (ITX), 1-chloro-2-propoxy-thioxanthone (CPTX), 2-chloro-thioxanthone (CTX), and 2,4-diethyl-thioxanthone (DETX), and mixtures thereof. Alternatively, thioxanthone photosensitizers may be used in the form of oligomers or polymers (such as OMNIPOL TX sold by IGM Resins, Genopol® TX-2 sold by Rahn, or SpeedCure 7010 sold by Lambson).

[0061] In one embodiment, the at least one further additive is a nonionic surfactant, and the UV-VIS curable sealant composition may contain one or more of the nonionic surfactants in an amount of about 0.01 to about 5 wt %, preferably about 0.05 to about 3 wt %, more preferably about 0.1 to about 2 wt %, and even more preferably about 0.2 to about 1 wt %.

[0062] As is well known to those skilled in the art, nonionic surfactants contain a hydrophilic portion and a hydrophobic portion and are uncharged. Preferably, the one or more nonionic surfactants used have a molecular weight of about 200 g / mol to about 3000 g / mol and / or contain one or more functional groups selected from hydroxyl groups and epoxide groups. More preferably, the one or more nonionic surfactants are selected from nonionic fluorinated surfactants and nonionic silicone surfactants.

[0063]

[0062] As used herein, the term "non-ionic fluorinated surfactant" includes non-ionic perfluoropolyether surfactants and non-ionic fluorosurfactants.

[0064] As used herein, the term "nonionic perfluoropolyether surfactant" means a nonionic surfactant comprising a perfluoropolyether backbone and one or more, preferably two or more, terminal functional groups selected from the group consisting of hydroxyl, epoxide, acrylate, methacrylate and trialkoxysilyl, preferably selected from the group consisting of hydroxyl and epoxide. Preferably, the nonionic perfluoropolyether surfactant has an average molecular weight (M) of less than about 2000 [g / mol]. nAs used herein, perfluoropolyether backbone means the residue of a perfluoropolyether polymer comprising randomly distributed repeat units selected from perfluoromethyleneoxy (-CF2O-) and perfluoroethyleneoxy (-CF2-CF2O-). The perfluoropolyether residue is connected directly to the terminal functional group or via a spacer selected from methylene(oxyethylene), 1,1-difluoroethylene-(oxyethylene), methylene-di(oxyethylene), 1,1-difluoroethylene-di(oxyethylene), methylene-tri(oxyethylene), 1,1-difluoroethylene-tri(oxyethylene), methylene-tetra(oxyethylene), 1,1-difluoroethylene-tetra(oxyethylene), methylene-penta(oxyethylene), 1,1-difluoroethylene-penta(oxyethylene), and linear or branched hydrocarbon groups, optionally fluorinated, and containing one or more urethane groups or one or more amide groups, and optionally one or more cyclic moieties, including saturated cyclic moieties (such as cyclohexylene) and aromatic cyclic moieties (such as phenylene). Preferably, the nonionic perfluoropolyether surfactant is functionalized with one or more hydroxyl and / or epoxide functional groups.

[0065]

[0064] Particularly suitable examples of non-ionic perfluoropolyether surfactants are commercially available from Solvay under the names Fluorolink® E10H, Fluorolink® MD700, Fluorolink® MD500, Fluorolink® AD1700, Fluorolink® E-series, and Fluorolink® S10.

[0066] As used herein, the term "nonionic fluorosurfactant" refers to a compound having a perfluoroalkyl chain CF3(CF2) xwhere x is an integer from 2 to 18. Preferably, the nonionic fluorosurfactant has an average molecular weight (M n Preferably, the non-ionic fluorosurfactant is a compound of general formula (VII): CF3(CF2) x (CH2) y E (VII) [In the formula, x is an integer from 2 to 18; y is an integer from 0 to 8; E is [ka] , -(CR2CR2O) z H, and -OSi(OR 20 )3 are selected wherein z is an integer from 0 to 15; R, which may be the same or different in each occurrence, is selected from hydrogen and methyl; R 20 is a C1-C4 alkyl group).

[0067]

[0066] The nonionic fluorosurfactant is selected from fluorinated epoxy monomers, preferably from the group of 3-perfluorooctyl-1,2-propene oxide (Fluorochem), 3-perfluorohexyl-1,2-epoxypropane (Sigma-Aldrich) (Chemical Co., Ltd) and / or 3-[2-(perfluorohexyl)ethoxy]-1,2-epoxypropane (TCI American).

[0068]

[0067] General formula (VIII-a) CF3(CF2) x (CH2) y (CR2CR2O) z H (VIII-a) [In the formula, x is an integer between 2 and 18; y is an integer between 0 and 8; z is an integer from 0 to 15; and and R, which may be the same or different in each occurrence, is selected from hydrogen and methyl, with hydrogen being particularly preferred. Nonionic fluorosurfactants of general formula (VIII-a) are commercially available under the names CHEMGUARD S550-100 or CHEMGUARD S550, CHEMGUARD S222N, CHEMGUARD S559-100 or CHEMGUARD S559, all commercialized by CHEMGUARD; Capstone™ FS-31, Capstone™ FS-35, Capstone™ FS-34, Capstone™ FS-30, Capstone™ FS-3100, all commercialized by Chemours. Nonionic fluorosurfactants of general formula (VIII-b) CF3(CF2) x (CH2) y OSi(OR 20 ) (VIII-b) [In the formula, x is an integer between 2 and 18; y is an integer from 0 to 8; and R 20 is a C1-C4 alkyl group. Nonionic fluorosurfactants of general formula (VIII-b) are commercially available under the names Dynasylan F8261 and Dynasylan F8263, commercialized by Evonik.

[0069] Nonionic fluorosurfactants of general formula (VIII-c) [ka] [In the formula, x is an integer from 2 to 18; y is an integer from 0 to 8; R 21is selected from hydrogen and a methyl group. Examples of nonionic fluorosurfactants of general formula (VIII-c) include, but are not limited to, 1H,1H,2H,2H-perfluorooctyl acrylate (Sigma-Aldrich), 1H,1H,2H,2H-perfluorooctyl methacrylate (Sigma-Aldrich), 1H,1H-perfluorooctyl acrylate (Sigma-Aldrich), 1H,1H-perfluorooctyl methacrylate (Sigma-Aldrich), 1H,1H-perfluoroheptyl acrylate (Sigma-Aldrich), and 1H,1H-perfluoroheptyl methacrylate (Sigma-Aldrich).

[0070] As used herein, nonionic silicone surfactants include di(methyl)siloxane (-(CH3)2SiO-) and / or methyl (C2-C 10 -Alkyl)siloxane (-(CH3)(C2-C 10 -alkyl)SiO-), wherein the silicone backbone contains randomly distributed repeating units selected from one or more methyl groups and / or C2-C 10 The alkyl groups may be independently substituted with aryl groups, polyesters optionally presenting terminal functional groups selected from hydroxyl, epoxide, and (meth)acrylate, polyethers such as polyalkylene glycols, including polyethylene glycol and polypropylene glycol, optionally presenting terminal functional groups selected from hydroxyl, epoxide, and (meth)acrylate, hydroxyl, epoxide, or (meth)acrylate groups, and / or wherein the silicone backbone may be connected directly or via a spacer to the terminal functional groups selected from hydroxyl, epoxide, and (meth)acrylate. The silicone backbone described herein may be connected to an aliphatic urethane acrylate or a fluorine-containing aliphatic urethane acrylate. Preferably, the nonionic silicone surfactant is characterized by an average molecular weight of less than about 3000 g / mol.

[0071]

[0070] Nonionic silicone surfactants include, but are not limited to, polymethylalkylsiloxanes such as BYK-077 and BYK-085 commercialized by BYK, polyester-modified polydimethylsiloxanes such as BYK-310 commercialized by BYK, polyether-modified polydimethylsiloxanes such as BYK-377, BYK-333, BYK-345, BYK-346 and BYK-348 commercialized by BYK, polyesters such as BYK-315 commercialized by BYK, Modified polymethylalkylsiloxanes, polyether-modified polymethylalkylsiloxanes such as BYK-341, BYK-320 and BYK-325 commercialized by BYK, hydroxy-functional polydimethylsiloxanes such as TEGOMER® HSI-2311 commercialized by Evonik, polyester-modified hydroxy-functional polydimethylsiloxanes such as BYK-370 and BYK-373 commercialized by BYK, polyether-modified hydroxy-functional polydimethylsiloxanes such as BYK-308 commercialized by BYK, Examples of suitable acryloxy-functional polydimethylsiloxanes include polyether polyester-modified hydroxy-functional polydimethylsiloxanes such as BYK-375 commercialized by BYK, epoxy-functional polydimethylsiloxanes such as TEGOMER® E-Si2330 commercialized by Evonik, acryloxy-functional polydimethylsiloxanes such as TEGOMER® V-SI2250 and TEGO® Rad2700 commercialized by Evonik, polyester-modified acryl-functional polydimethylsiloxanes such as BYK-371 commercialized by BYK, polyether-modified acryl-functional polydimethylsiloxanes such as TEGO® Rad2100 and TEGO® Rad2500 commercialized by Evonik, silicone-modified aliphatic urethane acrylates such as SUO-S3000 and SUO-S600NM commercialized by Polygon, and silicone- and fluorine-modified aliphatic urethane acrylates such as SUO-FS500 commercialized by Polygon.

[0072] In another embodiment, the at least one additional additive is an adhesion promoter, and the UV-VIS curable sealant composition may include one or more of such adhesion promoters. The one or more adhesion promoters useful for further improving the adhesion of the resulting photopolymer layer may include transition metal chelates, mercaptans, thiol-containing compounds, carboxylic acids, organophosphates, diols, alkoxysilanes, combinations of alkoxysilanes and hydroxy-functional polyorganosiloxanes, or combinations thereof. The one or more adhesion promoters may be unsaturated or epoxy-functional compounds. Suitable epoxy-functional compounds are known in the art and commercially available; see, for example, U.S. Pat. Nos. 4,087,585; 5,194,649; 5,248,715; and 5,744,507, column 45.

[0073]

[0072] The one or more adhesion promoters may preferably comprise an unsaturated or epoxy-functional alkoxysilane. Examples of suitable epoxy-functional alkoxysilanes include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, (epoxycyclohexyl)ethyldimethoxysilane, (epoxycyclohexyl)ethyldiethoxysilane, and combinations thereof. Examples of suitable unsaturated alkoxysilanes include vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hexenyltrimethoxysilane, undecylenyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltriethoxysilane, and combinations thereof.

[0074]

[0073] Preferred adhesion promoters are preferably selected from the group comprising Silquest A187 (Momentive), (3-glycidyloxypropyl)triethoxysilane (Sigma-Aldrich), (3-glycidyloxypropyl)trimethoxysilane (Sigma-Aldrich) and / or trimethoxy[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane (Sigma-Aldrich).

[0075] The UV-VIS curable sealant composition may contain one or more organic solvents. The one or more organic solvents are not particularly limited, but are preferably polar organic solvents. Examples of polar organic solvents include, but are not limited to, alcohols (e.g., methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, and fluorinated alcohols), ketones (e.g., acetone, methyl ethyl ketone, and cyclohexanone), carboxylic acid esters (e.g., methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, and ethyl propionate), and ethers (e.g., diethyl ether, dipropyl ether, tetrahydrofuran, and dioxane). These organic solvents may be used alone or in combination. The UV-VIS curable sealant composition may contain up to about 10 wt % of one or more organic solvents. Preferably, when present, the organic solvent is present in an amount of about 1 to about 7.5 wt %, more preferably about 2 to about 5 wt %. Alternatively, in another embodiment, the UV-VIS curable sealant composition does not contain any solvent, i.e., is solvent-free.

[0076] In one embodiment, the present invention relates to a method of sealing electrical contacts on an inkjet printhead, comprising: a) providing a UV-VIS curable sealant composition described herein; b) providing an assembly including a flexible circuit and a silicon chip; c) dispensing a UV-VIS curable sealant composition onto the electrical contacts connecting the silicon chip to the flexible circuit; d) curing or at least partially curing the UV-VIS curable sealant composition using a UV-VIS light source; Includes.

[0077]

[0076] Figure 3 illustrates, but is not limited to, one embodiment of an encapsulation method. After bonding, the assembly (17) of the silicon chip (2) and flexible printed circuit (3) is transferred to a dispensing station (18), where a quantity of uncured UV-VIS-curable sealant composition (19) is delivered to each area to be protected. The assembly (17) with the dispensed UV-VIS-curable sealant is then quickly moved to a curing station (20), where a UV-VIS lamp (21) cures the UV-VIS-curable sealant composition. Typically, UV-VIS curing is performed at wavelengths between 200 and 420 nm. Within this range, the UV-VIS-curable sealant composition achieves a high degree of conversion of its reactive functional groups. Post-exposure heat treatment is not required, simplifying the manufacturing process. After the curing process of the UV-VIS curable sealant composition, a high level of adhesion is achieved to the various materials that make up the assembly (17), namely, silicon and silicon compounds, gold or other metals, polyimides, protective coatings, etc., among others.

[0078] The methods described herein also include step d) of curing or at least partially curing the UV-VIS curable sealant composition from step c), wherein the curing step is carried out using a curing unit that is a UV-VIS light source. A suitable curing unit comprises a UV-VIS curing unit device that includes, as a source of actinic radiation, a light-emitting diode (LED) lamp or an arc discharge lamp, such as a medium-pressure mercury arc (MPMA) or metal vapor arc lamp, preferably providing radiation in the UV-A, UV-B, and UV-C regions of the electromagnetic spectrum. In contrast to medium-pressure mercury lamps, which have emission bands in the UV-A, UV-B, and UV-C regions of the electromagnetic spectrum, UV-LED lamps emit radiation in the UV-A region, for example, in the range of about 380 nm to about 410 nm. Furthermore, current UV-LED lamps emit quasi-monochromatic radiation, i.e., they emit only a single wavelength, such as 365 nm, 385 nm, 395 nm, or 405 nm. In a preferred embodiment, curing is carried out by means of a mercury lamp, in particular a medium pressure mercury lamp (MPMA).

[0079] The UV-VIS curable sealant composition preferably has a curing rate of at least 150 mJ / cm 2 a dose of at least 200 mJ / cm 2 and even more preferably at least 500 mJ / cm 2 to cure the UV-VIS curable sealant composition, wherein the irradiation dose can be measured using a UV Power Puck® II radiometer from EIT, Inc., USA.

[0080]

[0079] An epoxy-based coating is often placed on the bottom surface of the flexible circuit, which electrically insulates the copper tracks. A set of metal fingers or electrical contacts connects the flexible circuit to the silicon chip. In a preferred embodiment, the placement area may be subjected to a surface treatment before dispensing the UV-VIS curable sealant composition onto the metal fingers or electrical contacts. A preferred method of surface treatment is plasma treatment.

[0081] The plasma treatment serves to enhance the bonding of the UV-VIS curable sealant composition to the reservoir and / or epoxy-based coated surface, which can prevent ink penetration, particularly at the interface of various additional adhesives used in inkjet printhead assembly.

[0082] Plasma treatment can be performed by inducing polarization of the surface to which a gas such as oxygen, nitrogen, or carbon dioxide is attached. This polarization is facilitated by dipole and polar moieties activated by the plasma treatment on the surface. In a preferred embodiment, the plasma treatment is performed using nitrogen.

[0083]

[0082] To have a high throughput in the manufacturing process and the possibility of performing plasma treatment without the need for a vacuum for safety reasons, the Acxys atmospheric nitrogen plasma treatment device may be used. Treatment may be performed on both sides of the flexible circuit. It is preferable to perform the plasma treatment before bonding the silicon chip to avoid conditioning the front end of the ejector group, which should not be wetted for proper printing behavior. In another embodiment, it is also possible to perform the plasma treatment on only one of the two surfaces of the flexible circuit, for example to modify and particularly polarize the epoxy-coated surface.

[0084] To achieve good results in terms of wetting, the device should be set to a power of at least 1500 W with a nitrogen flow rate of at least 120 sccm. In a preferred embodiment, the device should be set to a power of at least 2000 W with a nitrogen flow rate of at least 120 sccm and a conveyor speed of at least 10 seconds per piece. The effectiveness of the plasma treatment can be monitored by contact angle as a function of time while the device is placed at room temperature.

[0085] One embodiment is directed to the use of the UV-VIS curable sealant composition described herein to manufacture an inkjet printhead, particularly to protect the electrical contacts between a flexible circuit and a silicon chip disposed in the inkjet printhead.

[0086]

[0085] Those skilled in the art may devise several modifications to the specific embodiments described above without departing from the spirit of the present invention, and such modifications are encompassed within the scope of the present invention.

[0087]

[0086] Additionally, all documents referenced throughout this specification are incorporated herein by reference in their entirety as if fully set forth herein. [Example]

[0088] Examples E1-E9 were prepared as follows: Each component was sequentially introduced into a suitable reaction vessel as listed from top to bottom in Table 1. The materials were mixed in a Thinky planetary mixer for two 30-minute cycles. After mixing, the resulting composition was introduced into a dispensing syringe.

[0089] Viscosity measurement: Plate P20 (approximately 0.2 cm 3 The measurements were carried out using a rotational viscometer (Reologica) equipped with a sample.

[0090]

[0089] [Table 1] JPEG2026504413000010.jpg156149

[0091] To measure the ink stability of the cured UV-VIS curable sealant composition, an immersion test was devised. The UV-VIS curable sealant composition was exposed to at least 500 mJ / cm2 of ink using a UV exposure device (Exfor5000) with broadband exposure in the UVA range (315-400 nm).2 The adhesive was cured independently with a dose of UV light focused onto the adhesive surface by fiber optics.

[0092] Examples E2 and E4-E8 were evaluated by immersing the front end of the printhead containing the cured UV-VIS curable sealant composition in a solvent-based ink at 45°C for one week. The front end of the printhead, particularly the UV-VIS curable sealant composition, was then observed to determine whether any relevant defects existed in the material. Observation was performed, particularly by observing the shape and color of the UV-VIS curable sealant composition under an optical microscope, and an attempt was made to remove the material using a knife. If there was no permeation associated with the interface or no change in the structure or shape of the adhesive, the composition was considered to have passed the stability test. Otherwise, it was classified as a failure. The results of the immersion test were as follows: E2: Fail E4: Fail E5: Fail E6: Pass E7: Fail E8: Fail

[0093] To perform the immersion tests, the following solvent-based inks were used: [Table 2]

[0094] A test was devised to measure the electrical insulating properties of UV-VIS curable sealant compositions against ink. Printheads containing cured UV-VIS curable sealant compositions E2 and E4-E8 were maintained under electrical tension by constantly wetting their front ends with fresh water-based ink. Water-based inks were chosen because they are more aggressive toward the silicon and conductive sites of the chip. Water-based inks also have higher electrical conductivity than solvent-based inks, which can easily penetrate the sealant composition and cause electrical shorts. If the UV-VIS curable sealant effectively protects the printhead's electrical contacts from electrical failure, this is considered a positive result.

[0095] The water-based ink wets the printhead front end and electrical contacts as well as the UV-VIS curable sealant composition. This electrical check is a good simulation of what may occur in the field, especially for printers installed during downtime. With the exception of composition E6, the other test sealant compositions developed electrical shorts or leakage after a few hours to about one week. If the sample in contact with the water-based ink shows no noticeable electrical defects (e.g., shorts) after one week, the test result is considered positive and is rated as a pass; otherwise, it is rated as a fail. E2: Fail E4: Fail E5: Fail E6: Pass E7: Fail E8: Fail

[0096]

[0095] The following water-based inks were used to conduct the electrical insulation tests: [Table 3]

Claims

1. 1. A UV-VIS curable sealant composition comprising: a) 25 to 40 wt % of at least one aromatic epoxide monomer or aromatic epoxide oligomer or mixtures thereof; b) 4 to 20 wt % of at least one epoxidized polyene; c) 20 to 35 wt % of at least one organic or inorganic filler or mixture thereof; d) 0.1 to 10 wt % of at least one cationic photoinitiator; e) 0-30 wt. % of at least one cationically curable cyclic compound different from a) and b); f) 0.05 to 3 wt % of a nonionic surfactant; and g) 0-30 wt % of at least one further additive selected from the group consisting of a photosensitizer, an adhesion promoter, or any mixture thereof, different from components a) to f). Including, The UV-VIS curable sealant composition has a viscosity of about 60,000 mPas to about 120,000 mPas at 25°C; Weight percentages are based on the total weight of the UV-VIS curable sealant composition. UV-VIS curable sealant composition.

2. a) 35 to 40 wt % of at least one aromatic epoxide monomer or aromatic epoxide oligomer or mixtures thereof; b) 5 to 15 wt % of at least one epoxidized polyene; c) 20-25 wt % of at least one organic or inorganic filler or mixture thereof; d) 3 to 10 wt % of at least one cationic photoinitiator; e) 0-30 wt. % of at least one cationically curable cyclic compound different from a) and b); f) 0.1 to 2 wt % of a nonionic surfactant; and g) 0-30 wt % of at least one further additive selected from the group consisting of a photosensitizer, an adhesion promoter, or any mixture thereof, different from components a) to f).

2. The UV-VIS curable sealant composition of claim 1, comprising:

3. The nonionic surfactant is di(methyl)siloxane (-(CH ３ ) ２ SiO-) and / or methyl (C ２ ~C １０ -alkyl)siloxanes, and containing one or more methyl groups and / or C ２ ~C １０ 3. The UV-VIS curable sealant composition according to claim 1, wherein the alkyl groups may be substituted independently of one another by aryl groups, polyesters, polymethylalkylsiloxanes.

4. The nonionic surfactant silicone surfactant is polymethyl (C ２ ~C １０ 4. The UV-VIS curable sealant composition of claim 3, wherein the siloxane is a siloxane having a hydroxyl group and a hydroxyl group.

5. The UV-VIS curable sealant composition of any one of claims 1 to 4, comprising about 20 to about 30 wt% of said compound e).

6. The UV-VIS curable sealant composition of any one of claims 1 to 5, wherein component b) is at least one epoxidized polybutadiene.

7. The UV-VIS curable sealant composition of any one of claims 1 to 6, wherein component c) has a size of 5 μm to 15 μm.

8. The UV-VIS curable sealant composition of any one of claims 1 to 7, wherein component c) has a refractive index at 400 nm of 1.2 to 1.

8.

9. The UV-VIS curable sealant composition according to any one of claims 1 to 8, wherein said component c) is at least one polymeric filler, preferably at least one PMMA-based filler.

10. 10. The UV-VIS curable sealant composition according to any one of claims 1 to 9, wherein component c) is at least one inorganic filler, preferably selected from the group consisting of glass, carbonate, talc and mixtures thereof.

11. 11. The UV-VIS curable sealant composition of any one of claims 1 to 10, wherein component d) is selected from the group consisting of triphenylsulfonium salts, diazonium salts, diaryliodonium salts, ferrocenium salts, metallocene compounds, and mixtures thereof.

12. An inkjet printhead comprising the UV-VIS curable sealant composition of any one of claims 1 to 11.

13. 1. A method of sealing electrical contacts on an inkjet printhead, comprising: a) providing a UV-VIS curable sealant composition according to any one of claims 1 to 11; b) providing an assembly including a flexible circuit and a silicon chip; c) dispensing the UV-VIS curable sealant composition onto the electrical contacts connecting the silicon chip to the flexible circuit; d) curing or at least partially curing the UV-VIS curable sealant composition using a UV-VIS light source; A method comprising:

14. 14. The method of claim 13, wherein after step b), step b1) comprises exposing at least one surface of the flexible circuit to a plasma treatment, preferably to a nitrogen plasma atmosphere.

15. Use of the UV-VIS curable sealant composition according to any one of claims 1 to 11 for the manufacture of an inkjet printhead.

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