Epoxy-based uv-vis-curable compositions

Abstract

The invention relates to A UV-VIS-curable composition comprising: a) about 20 to about 40 wt.% of at least one aromatic epoxide component, wherein the epoxy functionality is between 2 to 3; b) about 30 to about 50 wt.% of at least one cycloaliphatic epoxide component, b) being different than a); c) about 2 to about 20 wt.% of at least one ester-containing component; d) about 2 to about 12 wt.% of at least one fluorine-based component; e) about 1 to about 15 wt.% of at least one cationic photoinitiator; f) more than about 3 wt.% of at least one additive selected from the group consisting of surfactants and adhesion promoters or mixtures thereof; g)0 to 5 wt.% of at least one photosensitizer; and wherein the composition has a Tg-value of less than 100 °C and a viscosity between about 1000 m-Pas to about 4000 m-Pas at 25 °C, wherein the weight percents are based on the total weight of the UV-VIS-curable composition. The invention further relates to an inkjet printhead comprising said composition and a method of coating a silicon substrate, preferably a silicon wafer, with said UV-VIS-curable composition.

Description

[0001] EPOXY-BASED UV-VIS-CURABLE COMPOSITIONS

[0002] FIELD OF THE INVENTION

[0003]

[0001] The present invention relates to the technical field of UV-VIS-curable compositions useful for manufacturing an inkjet printhead, its use and a method for manufacturing an inkjet printhead assembly comprising the UV-VIS-curable composition.

[0004] BACKGROUND OF THE INVENTION

[0005]

[0002] A typical inkjet printhead cartridge, as described in the patent EP 1896262 B1 (see figure 1 therein) or in figure 1 , is made of a printhead ejection assembly constituted by a printhead chip bonded to a flexible printed circuit. The printhead silicon chip, also known as silicon ejector group, houses the electrical and hydraulic components to address the ink towards the various ejecting sites, energizing it on demand, to produce ink droplets for printing. A nozzle plate is applied on the top surface of the chip, to provide the nozzles for ink ejection. The whole ejection assembly is in turn bonded to a cartridge that contains the ink reservoir, closed by a lid. Suitable ink slots are present in the cartridge body to allow the ink to get the printhead chip and to arrive to the microfluidic circuit, either through the slots machined into the chip or from the chip edge, depending on the printhead layout.

[0006]

[0003] In the field of inkjet printing used in the solvent-based ink and water-based ink formulations, the materials used for protecting electronic component and defining microhydraulics, are usually epoxy or unsaturated resins. This material can react through UV-VIS-curable process. The benefit of this method is the capability to control the degree of cross-linking of the composition.

[0007]

[0004] One of the state-of-the-art problems are the defects in the manufacturing process of the silicon ejector group. The ejector group consists of a CMOS part and a MEMS part. The CMOS unit consists of a series of conductive and insulating layers used in order to manage the electrical signals. Into the MEMS area is realized the geometry of the resistors required to generate the ink bubble. Different layers of metal(s) are needed to eject the ink, but the presence of layers at different thickness create topographies that introduce different gaps between silicon wafer and nozzle plate. The crosslinking of the UV-VIS-curable composition used to manufacture the inkjet printhead, in other term the contraction driven by the crosslinking and solvent evaporation process, does not exacerbates the gap issue, thereby compromising the protection and sealing of interfaces once the orifice layer is thermally bonded onto the microhydraulic.

[0008]

[0005] Thus, there is a need to develop a UV-VIS-curable composition in order to reduce the gap unevenness and provide a smooth surface between nozzle plate and silicon wafer bonded to UV-VIS composition, with the aim of optimizing the interface that influences the behavior of the ink in the printhead.

[0009]

[0006] Furthermore, due to various types of inks used i.e. water- and solvent-based, the UV-VIS- curable composition should be compatible with such inks. The UV-VIS-curable composition should possess high chemical resistance and the proper mechanical flexibility for the application. As the deposition of the UV-curable composition on the silicon substrate is performed by means of spin-coating, the composition should have the right viscosity value. SUMMARY OF THE INVENTION

[0010]

[0007] In a first aspect the present invention relates to to a UV-VIS-curable composition comprising: a) 20 to 40 wt.% of at least one aromatic epoxide component, wherein the epoxy functionality is between 2 to 3; b) 30 to 50 wt.% of at least one cycloaliphatic epoxide component, b) being different than a); c) 2 to 20 wt.% of at least one ester-containing component; d) 2 to 12 wt.% of at least one fluorine-based component; e) 1 to 15 wt.% of at least one cationic photoinitiator; f) more than 3 wt.% of at least one additive selected from the group consisting of surfactants and adhesion promoters; g) 0 to 5 wt.% of at least one photosensitizer; and wherein the composition has a Tg-value of less than 100 °C and a viscosity between about 1000 m Pas to about 4000 m Pas at 25 °C, wherein the weight percents are based on the total weight of the UV-VIS-curable composition.

[0011]

[0008] In a second aspect the invention relates to an inkjet printhead comprising the UV-VIS-curable composition as described herein, in at least partially cured state.

[0012]

[0009] In a third aspect, the invention relates to a method for coating a silicon substrate, wherein the method comprises: a) providing a silicon substrate, in particular silicon wafer; b) depositing the UV-VIS-curable composition, described herein; c) rotationally spreading out said composition, in particular by spin-coating; d) at least partially, preferably completely, evaporating the solvent from said composition; e) applying a mask to the UV-VIS-curable composition to generate a photolithographic pattern; f) at least completely removing any uncured UV-VIS-curable composition; g) at least partially curing said composition.

[0013]

[0010] In a final aspect the present invention relates to the use of a UV-VIS-curable composition, described herein, for manufacturing the inkjet printhead described herein.

[0014]

[0011] It has been surprisingly found that the UV-VIS-curable compositions described herein provide at least the following advantages: chemical resistance or stability to various inks, especially to solvent-based inks, after curing; good adhesion and wettability to various substrates of an inkjet printhead; good thixotropy to be suitable for spin coating applications; fast and efficient curing temperatures and performance compatibility to high speed; manufacturing of printhead systems; and lower amount of solvent required.

[0015] BRIEF DESCRIPTION OF DRAWINGS / FIGURES

[0016]

[0012] Figure 1 shows a schematic representation of an inkjet printhead cartridge (1). Said cartridge (1) houses on its surface a printhead chip (2), provided with a nozzle plate (3). The line B-B shown in the figure is corresponding to the direction of the relative movement between the printing medium and the printhead, during printing. Ink drops are ejected from the nozzles by means of electrical signals sent from the printer to the printhead chip: a flexible printed circuit (4) is used to this purpose. Polyimide is often used for the flexible circuit substrate. A window is made on the surface of the flexible printed circuit, to allow the printhead chip to protrude, thereby the flexible printed circuit surrounds the chip. Conductive metal traces of the flexible printed circuit jut out from the window edges, to electrically contact the chip as lead wires. Contact regions (5) are provided to electrically communicate with the printer on another side of the flexible circuit. The electrical connections between the lead wires and the chip are ensured by a suitable bonding process such as tape automated bonding (TAB). The chip is provided near the perimeter with a plurality of bonding pads to allow the bonding process, housing the lead wires on their surface: therefore, the pad surface must be freely accessible by the bonding tool without being covered by any layer, until the bonding process is completed. Generally, although not in all cases, the pads are distributed near the short sides of the printhead chip.

[0017]

[0013] Figure 2 shows a cross-sectional view of the printhead chip (2) and flexible circuit. The view is along a direction perpendicular to the line B-B. The chip (2), which is a silicon substrate having conductive, resistive, dielectric and protective layers on its surface, is covered with a patterned barrier layer (6), in which the hydraulic printhead circuit with the ejection chambers (7) is based. The barrier layer, which is commonly a polymer, is covered by the nozzle plate (3), whose nozzles allow the ejection of the ink droplets (8). The bonding pads (9) are placed near the chip side housing the lead wires (10) protruding from the flexible printed circuit (4), which are bonded to the pad surface. The lead wires are the extension of the conductive traces (11) of the flexible printed circuit. A suitable adhesive layer (12) allows the fastening of the flexible printed circuit to the cartridge body. It additionally functions as an insulating protectant, preventing the conductive traces (11) from coming into contact mechanically or electrically with any part or material that could cause a damage or short-circuit. The UV-VIS-curable composition (not shown) is disposed between the silicon chip (2) and the nozzle plate (3).

[0018] DETAILED DESCRIPTION

[0019] Definitions

[0020]

[0014] The following definitions are to be used to interpret the meaning of the terms discussed in the description and recited in the claims.

[0021]

[0015] As used herein, the article "a" indicates one as well as more than one and does not necessarily limit its referent noun to the singular.

[0022]

[0016] As used herein, the term “about” means that the amount or value in question may be the value designated or some other value about the same. The phrases are intended to convey that similar values within a range of ± 5% of the indicated value promote equivalent results or effects according to the invention.

[0023]

[0017] The term “UV-VIS” as used herein is intended to mean irradiation having a wavelength component in the UV-VIS part of the electromagnetic spectrum; typically from 200 nm to 420 nm.

[0024]

[0018] As used herein, the term “at least one” is meant to define one or more than one, for example one or two or three.

[0019] As used herein, the term “and / or” means that either all or only one of the elements of said group may be present. For example, “A and / or B” shall mean “only A, or only B, or both A and B”. In the case of “only A”, the term also covers the possibility that B is absent, i.e. “only A, but not B”.

[0025]

[0020] The term “comprising” as used herein is intended to be non-exclusive and open-ended. Thus, for instance a UV-VIS-curable composition comprising a compound A may include other compounds besides A. However, the term “comprising” also covers, as a particular embodiment thereof, the more restrictive meanings of “consisting essentially of’ and “consisting of’, so that for instance “a UV-VIS- curable composition comprising A, B and optionally C” may also (essentially) consist of A and B, or (essentially) consist of A, B and C.

[0026]

[0021] Where the present description refers to “preferred” embodiments / features, combinations of these “preferred” embodiments / features shall also be deemed as disclosed as long as this combination of “preferred” embodiments / features is technically meaningful.

[0027]

[0022] The term “wt.%” denotes the amount of the referred component based on the entire / total weight of the UV-VIS-curable composition.

[0028]

[0023] When more than one component a) - g) is comprised in the UV-VIS-curable composition described herein, the described weight percentages refer to the total amount of said more than one components a) - g).

[0029]

[0024] The present invention relates to a UV-VIS-curable composition comprising: a) 20 to 40 wt.% of at least one aromatic epoxide component, wherein the epoxy functionality is between 2 to 3; b) 30 to 50 wt.% of at least one cycloaliphatic epoxide component, b) being different than a); c) 2 to 20 wt.% of at least one ester-containing component; d) 2 to 12 wt.% of at least one fluorine-based component; e) 1 to 15 wt.% of at least one cationic photoinitiator; f) more than 3 wt.% of at least one additive selected from the group consisting of surfactants and adhesion promoters or mixtures thereof; g) 0 to 5 wt.% of at least one photosensitizer; and wherein the composition has a Tg-value of less than 100 °C and a viscosity between about 1000 m Pas to about 4000 m Pas at 25 °C, wherein the weight percents are based on the total weight of the UV-VIS-curable composition.

[0030]

[0025] The UV-VIS-curable composition presents a Tg-value of less than 100 °C. In preferred embodiments, the Tg-value is less than 90 °C, more preferably less than 80 °C. The Tg-value plays an important role for the flexibility or deformability in the final step of the curing process, as described herein, where a high temperature (200 °C) is applied. Without being bound to any particular theory, the optimum Tg-value allows the curing composition to change conformations and thus the chains of the polymer are free to move. The reported Tg-value is for the last hard bake stage of the curing process, as described herein.

[0031]

[0026] The UV-VIS-curable composition presents a viscosity value between about 1000 m Pas to about 4000 m Pas at 25 °C, preferably between 2000 m Pas to about 3500 m Pas, the viscosity values being measured with rotational viscometer Reologica with a plate C40. The compositions having viscosity within these ranges provide the benefits as mentioned before, especially with regards to their suitablity to being applied by spin-coating technique in the manufacture of an inkjet printhead.

[0032]

[0027] The UV-VIS-curable composition comprises the at least one aromatic epoxide component (a) which is an aromatic epoxide monomer or aromatic epoxide oligomer component or a mixture thereof, described herein. Aromatic epoxide monomers or aromatic epoxide oligomers as used herein denote a component which contain reactive or curable epoxy group(s) as well as aromatic moieties. The at least one aromatic epoxide monomer and aromatic epoxide oligomer independently can have an epoxide functionality (number of epoxide groups per molecule) greater than 2, from about 2 to about 4; preferably from about 2 to about 3. The at least one aromatic epoxide component is present in an amount from about 20 to about 40 wt.%, preferably from about 20 to about 30 wt.%, even more preferably from about 20 to about 25 wt.% or from about 25 to about 35 wt.%.

[0033]

[0028] The aromatic epoxide monomer or aromatic epoxide oligomer may be derived from mononuclear phenols, such as for example, from resorcinol or hydroquinone, or may be based on polynuclear phenols, such as, for example, bis-(4-hydroxyphenyl)methane (bisphenol F), 2,2-bis(4- hydroxyphenyl)propane (bisphenol A), or on condensation products obtained under acidic conditions of phenols or cresols with formaldehyde, generally known as novolacs, especially phenol novolaks and cresol novolacs.

[0034]

[0029] Suitable commercially available aromatic epoxide monomers or aromatic epoxide oligomers are, but not limited to, the ARALDITE® GY series that is Bisphenol A epoxy liquid resins, the ARALDITE® CT and GT series that is Bisphenol A epoxy solid resins, the ARALDITE® GY and PY series that is Bisphenol F epoxy liquids, the ARALDITE® ECN series of epoxy cresol novolacs, the ARALDITE® EPN series of epoxy phenol novolacs, DEN series of epoxy Novolac resins from PalmerHolland.

[0035]

[0030] In an embodiment, the UV-curable composition comprises at least one component having an ester-containing functionality (i.e. an ester-containing component) c), described herein. The ester- containing component may serve as a (reactive) solvent in addition to any other solvent that may be added to the UV-VIS-curable composition. The ester-containing component can be any suitable ester, like a non-cyclic ester or even preferably a cyclic ester. The component with ester-functionality may have an additional functional group, as long as the additional functional group does not interfere in a disadvantageous manner to the UV-VIS-curable composition. The component with ester-functionality may be present from about 2 to about 20 wt.%, preferably from about 15 to about 20 wt.%. Without being bound to any particular theory, it is assumed that the solvent with ester-functionality engages in a transesterification reaction with the aromatic epoxide oligomer or monomer component a) and during this reaction the solvent creates a bonding with the component a).

[0036]

[0031] Suitable ester-containing components include without limitation benzyl benzoate, bis(2- ethylhexyl) adipate, bis(2-ethylhexyl) phthalate, bis(2-ethylhexyl) terephthalate, 2-butoxyethanol acetate, butyl acetate, s-butyl acetate, t-butyl acetate, diethyl carbonate, dimethyl adipate, ethyl acetate, ethyl acetoacetate, ethyl butyrate, ethyl lactate, ethylene carbonate, hexyl acetate, isoamyl acetate, isobutyl acetate, isopropyl acetate, methyl acetate, methyl lactate, methyl phenylacetate, methyl propionate, propyl acetate, propylene carbonate, triacetin, ethyl 6-hydroxy hexanoate.

[0032] Suitable cyclic esters include without limitation e-caprolactone such as p-methyl-6- valerolactone, 6-valerolactone, e-caprolactone, 2-methyl-e-caprolactone, 3-methyl-e-caprolactone, 4- methyl-e-caprolactone, 5-tert-butyl-e-caprolactone, 7-methyl-e-caprolactone, 4,4,6-e- caprolactone trimethyl-e-caprolactone 4,6,6-trimethyl-e-caprolactone, or mixtures thereof.

[0037]

[0033] In an embodiment, the UV-curable composition comprises at least one component having at least one fluorine atom (i.e., fluorine-based component) d), described herein. The fluorine-based component is present in an amount from about 2 to about 12 wt.%, preferably from about 5 to about 11 wt.%. The fluorine-based component is different than the other components included in the UV-VIS- curable composition.

[0038]

[0034] In a preferred embodiment, the fluorine-based component contains multiple, i.e. more than one, fluorine atom as well as another functional group, preferably a hydroxy (-OH) group. Suitable examples include but are not limited to 1 ,1 ,1 ,3,3,3-hexafluoro-2-propanol, 2,2,2-trifluoroethanol, 4,4,4-trifluoro-1 - butanol, 4, 4, 5, 5, 5 -pentafluoro-1 -pentanol, 2- (perfluorohexyl) ethanol, 3- (2-perfluorohexylethoxy) -1 ,2- dihydroxypropane, 2, 2, 3, 3, 4, 4, 5, 5 , 6,6,7,7,8,8,8-pentadecafluoro-1-octanol, 2,2-bis (trifluoromethyl) propanol, 1 H, 1 H, 3H-hexafluorobutanol, 2H-hexafluoro- 2-propanol, 1 H, 1 H, 7H-dodecafluorohexanol, 1 H, 1 H, 3H-tetrafluoropropanol, 6- (perfluoro-1 -methoxyethyl) hexano 1 H, 1 H-2,5-di (trifluoromethyl) - 3,6-dioxaundecafluorononanol, 6- (perfluorohexyl) hexanol, 3- (perfluoro hexyl) propanol, 2- (perfluorohexyl) ethanol, 2-perfluoropropoxy-2,3,3,3-tetrafluoropropanol, 6- (perfluorobutyl) hexanol, 3- (perfluorobutyl) propanol, 2- (perfluorobutyl) ethanol 1 H, 1 H-heptafluorobutanol, 6- (perfluoroethyl) hexanol, 1 H, 1 H-pentafluoropropanol, 1 H, 1 H-trifluoroethanol.

[0039]

[0035] Even more preferred examples of fluorine-based component include but are not limited to 2- hydroxy-2-phenyl-hexafluoropropane, 1 ,3-bis (hexafluoro-2-hydroxy-2-propyl) benzene, 1 ,4-bis (hexafluoro-2-hydroxy-2-propyl) benzene, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-1 ,8-octanediol, 2, 2, 3, 3, 4, 4, 5, 5- octafluoro-1 ,6-hexanediol.

[0040]

[0036] The UV-VIS-curable composition comprises the at least one cationic photoinitiator e), described herein, in an amount from about 1 to about 15 wt.%, preferably from about 3 to about 12 wt.%, more preferably from about 4 to about 10 wt.%. According to one embodiment, the at least one cationic photoinitiator is an onium salt and 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 still more preferably selected from the group consisting of iodonium salts, sulfonium salts and mixtures thereof.

[0041]

[0037] The iodonium salts described herein have a cationic moiety and an anionic moiety, wherein the anionic moiety is preferably BFr, B(C6F5)4“, PFe“, AsFe-, SbFe- or CF3SO3-, more preferably SbFe- or PF6- and wherein the cationic moiety is preferably an aromatic iodonium ion, more preferably a iodonium ion comprising two aryl groups, wherein the two aryl groups may be independently substituted by one or more alkyls groups (such as for example methyl, ethyl, isobutyl, tertbutyl, etc.) one or more alkoxy groups, one or more nitro groups, one or more halogen containing groups, one or more hydroxy groups or a combination thereof. Particularly suitable examples of iodonium salts for the present invention are commercially available under the name Omnicat 250 and 440 from IGM Resins and SpeedCure 938 from Lambson.

[0042]

[0038] The sulfonium salts described herein have a cationic moiety and an anionic moiety, wherein the anionic moiety is preferably, BFr, B(CeF5)4-, PFe-, (PFe-m(CnF2n-i)m)- (where m is an integer from 1 to 5, and n is an integer from 1 to 4), AsFe-, SbFe-, CF3SO3-, perfluoroalkyl sulfonate or pentafluorohydroxyantimonate, more preferably SbFe- or PFe- and wherein the cationic moiety is preferably an aromatic sulfonium ion, more preferably a sulfonium ion comprising two or more aryl groups, wherein the two or more aryl groups may be independently substituted by one or more alkyls groups (such as for example methyl, ethyl, isobutyl, tertbutyl, etc.) one or more alkoxy groups, one or more aryloxyl groups, one or more halogen containing groups, one or more hydroxy groups or a combination thereof.

[0043]

[0039] Suitable examples of sulfonium ions comprising two or more aryl groups include without limitation triarylsulfonium ions, diphenyl[4-(phenylthio)phenyl] sulfonium ion, bis[4- (diphenylsulfonio)phenyl] sulfonium ion, triphenylsulfonium ions and tris[4-(4- acetylphenyl)sulfanylphenyl] sulfonium ion.

[0044]

[0040] In a preferred embodiment, the at least one cationic photoinitiator e) is selected from the group consisting of triphenylsulfonium salts, diazonium salts, diaryliodonium salts, ferrocenium salts, metallocene compounds and mixtures thereof.

[0045]

[0041] Suitable commercially available cationic photoinitiators e) are, but not limited to, Irgacure PAG 290 (BASF), diphenyliodonium hexafluorophosphate (Sigma-Aldrich), diphenyliodonium hexafluoroantimonate (Sigma-Aldrich), triarylsulfonium hexafluorophosphate salts (Sigma Aldrich) and / or triphenylsulfonium tritiate (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 arylsulphonium hexafluorophosphate (ESACURE 1064, Lamberti). Arylsulphonium hexafluorophosphate (ESACURE 1064, Lamberti), bis-(4-dodecylphenyl)iodonium hexafluroantimonate 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) from Arkema, diphenyl[(phenylthio)phenyl]sulphonium (PAG-20001), mixed type triarylsulfonium hexafluoroantimonate salts PAG-20002 or PAG-21608 from Aalchem.

[0046]

[0042] Other examples of useful photo initiators can be found in standard textbooks such as "Chemistry & Technology of UV & EB Formulation for Coatings, Inks & Paints", Volume III, "Photoinitiators for Free Radical Cationic and Anionic Polymerization", 2nd edition, by J. V. Crivello & K. Dietliker, edited by G. Bradley and published in 1998 by John Wiley & Sons in association with SITA Technology Limited.

[0047]

[0043] The UV-VIS-curable composition comprises at least one cycloaliphatic epoxide component b) , wherein said at least one cycloaliphatic epoxide component b) is different than the component a) as well as other components added to the UV-VIS-curable composition.

[0048]

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

[0049]

[0045] According to one embodiment, X is a divalent hydrocarbon group being a straight- or branched- chain alkylene group comprising from one to eighteen carbon atoms, wherein examples of said straight- or branched-chain alkylene group include without limitation methylene group, methylmethylene group, dimethylmethylene group, ethylene group, propylene group, and trimethylene group.

[0050]

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

[0051]

[0047] According to one embodiment, X is a divalent group comprising one or more oxygen-containing linkage groups being -CO-, -O-CO-O-, -COO- and -O-. According to one embodiment, preferred epoxy derivatives comprising more than one cyclohexane oxide groups and having the structural formula (I), wherein X is a divalent group comprising one or more oxygen-containing linkage groups being -CO-, - O-CO-O-, -COO-, -O-, have the structural formula (II), (III) or (IV): which corresponds to 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylates wherein Ri - R9independently are hydrogen or linear or branched alkyl radicals containing from one to ten carbon atoms and preferably containing from one to three carbon atoms (such as methyl, ethyl, n-propyl, i-propyl, n- butyl, i-butyl, s-butyl, t-butyl, hexyl, octyl, and decyl), preferably cycloaliphatic epoxides having the 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; which corresponds to cycloaliphatic diepoxide esters of dicarboxylic acids, wherein Ri - R9independently are hydrogen or linear or branched alkyl radicals containing from one to ten carbon atoms and preferably containing from one to three carbon atoms (such as methyl, ethyl, n-propyl, isopropyl, butyl, hexyl, octyl, and decyl) and A is a valence bond or a linear or branched divalent hydrocarbon radical generally containing from one to ten carbon atoms and preferably containing from 3 to 8 carbon atoms, such as alkylene radicals (such as for example trimethylene, tetramethylene, hexamethylene and 2-ethylhexylene) and cycloaliphatic radicals (such as 1 ,4-cyclohexane, 1 ,3-cyclohexane and 1 ,2- cyclohexane); preferably cycloaliphatic diepoxide esters of dicarboxylic acids having the structural formula (III) are 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; wherein Ri - Rg independently are hydrogen or linear or branched hydrocarbon radicals containing one to three carbon atoms; a preferred example of cycloaliphatic diepoxides having the structural formula (IV) is 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meta-dioxane.

[0052]

[0048] According to one embodiment, the cycloaliphatic epoxide components described herein have the structural formula

[0049] The cycloaliphatic epoxide components described herein may be hydroxy modified or (meth)acrylate modified. Examples are commercially available under the name Cyclomer A400 (CAS: 64630-63-3) and Cyclomer M100 (CAS: 82428-30-6) by Daicel Corp., or TTA 15 and TTA16 by TetraChem / Jiangsu, Celloxide 2021 P by Daicel, CYRACURE™ 6110 UVR, CYRACURE™ 6105 UVR by Dow Chemical, 3,4 epoxycyclohexylmethyl 3’, 4’- epoxycyclohexanecarboxylate from Sigma Aldrich or as ACHWL CER 4221 from PHLEX TEK, 7-oxabicyclo[4.1 ,0]hept-3-ylmethyl 7- oxabicyclo[4.1 .0]heptane-3-carboxylate (UviCure S105) from Arkema.

[0053]

[0050] The UV-VIS-curable composition may comprise at least one filler. The filler may either be an organic filler or an inorganic filler or a mixture thereof. The at least one filler is preferably present in an amount from about 15 to about 35 wt.%, more preferably in an amount from about 20 to about 25 wt.%. In a preferred embodiment, the filler has a refractive index from about 1 .2 to about 1 .8, preferably from about 1.3 to about 1.6 at 400 nm and / or a particle size from about 5 to about 15 pm, preferably from about 5 to about 9 pm.

[0054]

[0051] The refractive index of the at least one filler maybe measured using ISO 489:2022, while the particle size may be determined by laser diffraction method using ISO 13320:2020. Furthermore, refractive indices of various materials are also available from refractiveindex.info.

[0055]

[0052] Inorganic fillers may be preferably selected from the group consisting of carbon fibers, talcs, micas (muscovites), wollastonites, calcinated clays, china clays, kaolins, 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 hydrates, silica, fumed silica, montmorillonites, graphites, anatases, rutiles, bentonites, vermiculites, zinc whites, zinc sulfides, wood flours, quartz flours, natural fibers, synthetic fibers, glass and mixtures thereof. Preferred inorganic fillers may be selected from the group consisting of glasses, carbonates, talcs and mixtures thereof. A particularly preferred inorganic filler is talc.

[0056]

[0053] Preferably, the filler is an organic filler. The organic filler may be selected from the group consisting of acrylic resins produced from at least either acrylic ester or methacrylic ester, copolymers thereof 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 butyrals, polyacrylic polyols, polyvinyl alcohols, polyurethanes, hydrogenated petroleum resins, and mixtures thereof. Advantageously, polymeric acrylic resins based on PMMA (polymethylmethacrylate), PMMA-DEGDA ((polymethylmethacrylate diethylene glycol diacrylate), PBMA (polybutylmethacrylate), and PiBMA (polyisobutylmethacrylate) are preferred. Other suitable resins are crosslinked poly(styrene-co-divinylbenzene) or poly(4-vinylpyridine-co- ethylvinylbenzene). In a preferred embodiment, the organic polymeric fillers have a particle size of < 10 pm. When the filler has a particle size described herein, its compatibility in the UV-VIS-curable composition is improved and said composition maintains high homogeneity as well as form or shape stability after dispensing. The acrylic resins impart desired rheological properties without inducing any weakness in the composition from the point of chemical robustness and / or stability over time.

[0057]

[0054] According to a preferred embodiment, the UV-VIS-curable composition may comprise one or more oxetane compounds or compounds having oxetane functional group, as described herein. For embodiments wherein the UV-VIS-curable composition described herein comprises the one or more oxetanes, said one or more oxetanes being present in an amount less than or equal to about 30 wt.%, preferably larger than or equal to about 5 wt.% and less than or equal to about 25 wt.%.

[0058]

[0055] Preferred examples of oxetanes include trimethylene oxide, 3,3-dimethyloxetane, trimethylolpropane oxetane, 3-ethyl-3-hydroxymethyl oxetane, 3-ethyl-3-[(2-ethylhexyloxy) methyl]oxetane, 3,3-dicyclomethyl oxetane, 3-ethyl-3-phenoxymethyl oxetane, bis ([1-ethyl(3- oxetany I)] methyl) ether, 1 ,4-bis [3-ethyl-3-oxetanyl methoxy)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. The one or more oxetanes described herein may be hydroxy modified or (meth)acrylate modified.

[0059]

[0056] Suitable commercially available examples of oxetanes are, but not limited to, OXT221 (Toagosei Chemical), 3-ethyl-3-oxetanemethanol (Sigma-Aldrich), 3,3-dimethyloxetane (Sigma-Aldrich) and / or 3- ethyl-3-[(2-ethylhexyloxy)methyl]oxetane (OXT 212)(Toagosei chemical).

[0060]

[0057] The UV-VIS-curable composition may comprise at least one photosensitizer g), described herein. Photosensitizers are activated by one or more of the wavelengths emitted by the UV-VIS light source and reach an excited state. The excited photosensitizer then transfer energy to the at least one cationic photoinitiators, which in turn initiates the polymerization process. The at least one photosensitizer is preferably present in an amount from about 0 to about 5 wt.%, more preferably about preferably from about 0.2 to about 1 wt.%.

[0061]

[0058] Commercially available photosensitizers are, but 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 Kasei Chemicals Ltd) and titanocene derivatives (such as Irgacure® 784 sold by BASF). Other suitable photosensitizers include without limitation 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 an oligomeric or polymeric form (such as OMNIPOL TX sold by IGM Resins, Genopol*® TX-2 sold by Rahn, or SpeedCure 7010 sold by Lambson).

[0062]

[0059] The UV-VIS-curable composition may comprise at least one additive component f), described herein, selected from the group consisting of surfactants, adhesion promoters and mixtures thereof wherein the additive f) is different from the components a) to g), and wherein the amount of said at least one additive is greater than 3 wt.% or preferably from about 5 to about 20 wt.%, even more preferably from about 5 to about 15 wt.%.

[0063]

[0060] In an embodiment, said at least one additive is a non-ionic surfactant and the UV-VIS-curable composition may comprise one or more of said non-ionic surfactants in an amount from about 3 to about 10 wt.%, preferably from about 3.5 to about 5 wt.%. In case the amount of surfactant is less than or equal to 3 wt.%, another additional additive, like adhesion promoter, is added in at least the amount needed to bring the total amount of the additves to more than 3 wt.%.

[0064]

[0061] As well known to a skilled person, non-ionic surfactants contain a hydrophilic moiety and a hydrophobic moiety and carry no charge. Preferably, the one or more non-ionic surfactants used have a molecular weight of between about 200 g / mol and about 3000 g / mol, and / or contain one or more functional groups selected from hydroxyl and epoxide groups. More preferably, the one or more nonionic surfactants is selected from non-ionic fluorinated surfactants and a non-ionic silicone surfactants.

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

[0065]

[0063] As used herein, the term “non-ionic perfluoropolyether surfactant” denotes a non-ionic 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 non- ionic perfluoropolyether surfactant is characterized by an average molecular weight (Mn) below about 2000 [g / mol]. As used herein, a perfluoropolyether backbone denotes a residue of a perfluoropolyether polymer comprising randomly distributed recurring units selected from perfluoromethyleneoxy (-CF2O-) and perfluoroethyleneoxy (-CF2-CF2O-). The perfluoropolyether residue is connected to the terminal functional group directly 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 a linear or branched hydrocarbon group, optionally fluorinated at the carbon atom connecting the spacer to the perfluoropolyether residue, 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 non- ionic perfluoropolyether surfactant is functionalized with one or more hydroxyl and / or epoxide functional groups.

[0066]

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

[0067]

[0065] As used herein the term “non-ionic fluorosurfactant” refers to a non-ionic surfactant containing a perfluoroalkyl chain CF3(CF2)x, wherein x is an integer from 2 to 18. Preferably, the non-ionic fluorosurfactant is characterized by an average molecular weight (Mn) from about 200 [g / mol] to about 2000 [g / mol]. Preferably, the non-ionic fluorosurfactant is a compound of general formula (VII)

[0068] CF3(CF2)x(CH2)yE

[0069] (VII) wherein x is an integer from 2 to 18; y is an integer from 0 to 8; and

[0070] E is selected from

[0071] -(CR2CR2O)ZH, and -OSi(OR20)3, wherein z is an integer from 0 to 15;

[0072] R can be the same, or different in each occurrence, and is selected from hydrogen and methyl; and R20is a C1-C4 alkyl group.

[0073]

[0066] Said non-ionic fluorosurfactant may be selected from fluorurated epoxy monomer, preferably selected from the group 3-perfluorooctyl-1 ,2-propenoxide (Fluorochem), 3-perfluorohexyl-1 ,2- epoxypropane (Sigma-Aldrich) (Chemical Co., Ltd) and / or 3-[2-(perfluorohexyl)ethoxy]-1 ,2- epoxypropane (TCI American).

[0074]

[0067] A non-ionic fluorosurfactant of general formula (Vlll-a)

[0075] CF3(CF2)x(CH2)y(CR2CR2O)zH

[0076] (Vlll-a) wherein x is an integer from 2 to 18; y is an integer from 0 to 8; z is an integer from 0 to 15; and

[0077] R can be the same, or different in each occurrence, and is selected from hydrogen and methyl, preferably hydrogen is especially preferred. Non-ionic fluorosurfactants of general formula (Vlll-a) are commercially available under the name 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.

[0078] A non-ionic fluorosurfactant of general formula (Vlll-b)

[0079] CF3(CF2)x(CH2)yOSi(OR20)

[0080] (Vlll-b), wherein x is an integer from 2 to 18; y is an integer from 0 to 8; and

[0081] R20is a Ci-C4alkyl group, is also preferred. Non-ionic fluorosurfactants of general formula (Vlll-b) are commercially available under the name Dynasylan F8261 and Dynasylan F8263 commercialized by Evonik.

[0082]

[0068] A non-ionic fluorosurfactant of general formula (Vlll-c) wherein x is an integer from 2 to 18; y is an integer from 0 to 8; and

[0083] R21is selected from hydrogen and a methyl group, is also preferred. Examples of non-ionic fluorosurfactants of general formula (Vlll-c) include, but are not limited to: 1 H, 1 / 7,2 / 7,2 / 7-perfluorooctyl acrylate (Sigma-Aldrich), 1 H, 1 / 7,2 / 7,2 / 7-perfluorooctyl methacrylate (Sigma-Aldrich), 1 / 7, 1 / 7- perfluorooctyl acrylate (Sigma-Aldrich), 1 / 7,1 / 7-perfluorooctyl methacrylate (Sigma-Aldrich), 1 / 7, 1 / 7- perfluoroheptyl acrylate (Sigma-Aldrich) and 1 / 7,1 / 7-perfluoroheptyl methacrylate (Sigma-Aldrich).

[0084]

[0069] As used herein a non-ionic silicone surfactant refers to a non-ionic surfactant comprising a silicone backbone containing randomly distributed recurring units selected from di(methyl)siloxane (- (CH3)2SiO-) and / or methyl-(C2-Cio-alkyl)-siloxane (-(CH3)(C2-Cio-alkyl)SiO-), wherein one or more methyl groups and / or C2-Cio-alkyl groups may be independently of each other substituted by an aryl group, a polyester, optionally presenting a terminal functional group selected from hydroxyl, epoxide, and (meth)acrylate, a polyether, such as polyalkylene glycol, including polyethylene glycol and polypropylene glycol, optionally presenting a terminal functional group selected from hydroxyl, epoxide and (meth)acrylate, a hydroxyl group, an epoxide group, or a (meth)acrylate group, and / or wherein the silicone backbone may be connected directly or via a spacer to a terminal functional group selected from a hydroxyl group, an epoxide group, and a (meth)acrylate group. The silicone backbone described herein may be connected to an aliphatic urethane acrylate or to a fluorine-containing aliphatic urethane acrylate. Preferably, the non-ionic silicone surfactant is characterized by an average molecular weight lower than about 3000 g / mol.

[0085]

[0070] Non-ionic silicone surfactants include, but are not limited to poly-methyl-alkyl-siloxane, such as BYK-077 and BYK-085 commercialized by BYK, polyester-modified poly-dimethyl-siloxane, such as BYK 310 commercialized by BYK, polyether-modified poly-dimethyl-siloxane, such as BYK-377, BYK- 333, BYK-345, BYK-346 and BYK-348 commercialized by BYK, polyester-modified poly-methyl-alkyl- siloxane, such as BYK-315 commercialized by BYK, polyether-modified poly-methyl-alkyl-siloxane, such as BYK-341 , BYK-320 and BYK-325 commercialized by BYK, hydroxy-functional poly-dimethyl- siloxane, such as TEGOMER® HSI-2311 commercialized by Evonik, polyester-modified hydroxyfunctional poly-dimethyl-siloxane, such as BYK-370 and BYK-373 commercialized by BYK, polyether- modified hydroxy-functional polydimethylsiloxane, such as BYK-308 commercialized by BYK, polyetherpolyester modified hydroxy-functional polydimethylsiloxane, such as BYK-375 commercialized by BYK, epoxy-functional poly-dimethyl-siloxane, such as TEGOMER® E-Si 2330 commercialized by Evonik, acryloxy-functional poly-dimethyl-siloxane, such as TEGOMER® V-SI 2250 and TEGO® Rad 2700 commercialized by Evonik, polyester-modified acrylic functional poly-dimethyl-siloxane, such as BYK- 371 commercialized by BYK, polyether-modified acrylic functional poly-dimethyl-siloxane, such as TEGO® Rad 2100 and TEGO® Rad 2500 commercialized by Evonik, silicone-modified aliphatic urethane acrylate, such as SUO-S3000 and SUO-S600NM commercialized by Polygon, silicone- and fluorinemodified aliphatic urethane acrylate, such as SUO-FS500 commercialized by Polygon.

[0086]

[0071] In another embodiment, said at least one additive is an adhesion promoter and the UV-VIS- curable composition may comprise one or more of said adhesion promoters. The adhesion promoter may be present from about 0.01 to about 0.1 wt.%, preferably from about 0.02 to about 0.05 wt.%. The one or more adhesion promoters, useful to further improve the adhesion of the resulting photopolymer layer, can comprise a transition metal chelate, a mercaptan, a thiol-containing compound, a carboxylic acid, an organic phosphoric acid, a diol, an alkoxysilane, a combination of an alkoxysilane and a hydroxy-functional polyorganosiloxane, or a combination thereof. The one or more adhesion promoters can be unsaturated or epoxy-functional compound. 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 col. 45.

[0087]

[0072] The one or more adhesion promoters may preferably comprise an unsaturated or epoxyfunctional alkoxysilane. Examples of suitable epoxy-functional alkoxysilanes include 3- glycidoxypropyltrimethoxysilane, 3-glycidoxypropyl- triethoxysilane, (epoxycyclohexyl) ethyldimethoxysilane, (epoxycyclohexyl)- ethyldiethoxysilane and combinations thereof. Examples of suitable unsaturated alkoxysilanes include vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hexenyl-trimethoxysilane, undecylenyltrimethoxysilane, 3- methacryloyloxypropyl trimethoxysilane, 3-methacryloyloxypropyl triethoxy-silane, 3-acryloyloxypropyl trimethoxysilane, 3- acryloyloxypropyl triethoxy- silane, and combinations thereof.

[0088]

[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).

[0089]

[0074] The UV-VIS-curable composition may comprise one or more other organic solvents, in addition to the component with ester functionality mentioned before. The one or more organic solvents are not particularly limited but are preferably apolar organic solvent. Examples of the polar organic solvent 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 composition may contain up to about 10 wt.% of the one or more organic solvents. Preferably and when present, the one or more organic solvents are present in a total amount from about 1 to about 7.5 wt.%, more preferably from about 2 to about 5 wt.%. Alternatively, in another embodiment, the UV-VIS-curable composition does not contain any solvent i.e. it is solvent-free.

[0090]

[0075] In another embodiment, the invention relates to a method for coating a silicon substrate, wherein the method comprises: a) providing a silicon substrate, in particular silicon wafer; b) depositing the UV-VIS-curable composition according to claims 1 to 7; c) rotationally spreading out said composition, in particular by spin-coating; d) at least partially, preferably completely, evaporating the solvent from said composition; e) applying a mask to the UV-VIS-curable composition to generate a photolithographic pattern; f) at least completely removing any uncured UV-VIS-curable composition; g) at least partially curing said composition.

[0091]

[0076] The masking step may be performed by any commercially available high precision mask aligner for (photo)lithography applications. An example of one such mask aligner is from Karl Suss KG Gmbh & Co, type: 170542 (Nr: 712). In this system the mask and the silicon substrate, preferably silicon wafer, are in contact for about 30 seconds. The material of the mask is quartz with a chrome pattern. The UV- radiation reflects on the chrome pattern but traverses the quartz thereby generating a photolithographic pattern. An alternative contactless method, wherein contact with the silicon substrate is avoided may be performed by a device like Ultratech Saturn Spectrum III stepper.

[0092]

[0077] The removing of any uncured or uncrosslinked UV-VIS-curable composition may be performed by means of spray coating using a suitable solvent. In case spray coating is performed, the solvent may then be removed using a suitable vacuum system.

[0093]

[0078] One embodiment is directed to the use of an UV-VIS-curable composition described herein for manufacturing an inkjet printhead.

[0094]

[0079] Another embodiment relates to an inkjet printhead comprising the UV-VIS-curable composition as described herein, in at least partially cured state.

[0095]

[0080] The skilled person can envisage several modifications to the specific embodiments described above without departing from the spirit of the present invention. Such modifications are encompassed within the present invention.

[0096]

[0081] Further, all documents referred to throughout this specification are hereby incorporated by reference in their entirety as set forth in full herein.

[0097] EXAMPLES

[0098]

[0082] The examples E1 - E9 were prepared as follows. Each ingredient was successively introduced in a suitable reaction container as listed in table 1 , from top to bottom. The materials were mixed in a Thinky planetary mixture for 5 cycles of 30 min each. After mixing, the resulting composition was introduced into syringes for dispensing.

[0099]

[0083] Viscosity measurement: performed by means of a rotational viscometer Reologica with a plate C40 (about 0.2 cm3sample).

[0100] Table 1

[0101]

[0102] Table 2 not tested

[0103]

[0084] The spin coating process on a silicon substrate, particularly a silicon wafer, is performed by means of Laurell - WS 400BZ-6NPP / LITE equipment by the following steps:

[0104] 1. Setting the spin coating conditions (typically the following were used: 20s at 250 rpm, 20s at 500 rpm or 60s at 3900 rpm, depending on the viscosity of the UV-VIS-curable composition);

[0105] 2. Placing the silicon wafer on the instrument;

[0106] 3. Adding about 12 mL of the UV-VIS-curable composition onto the silicon substrate;

[0107] 4. Setting the vacuum on the instrument to adhere the silicon substrate with UV-VIS-curable composition to the instrument;

[0108] 5. Pressing run;

[0109] 6. Soft baking on a hot plate (about 160°C for 30 min).

[0110]

[0085] The curing process for the UV-VIS-curable composition may be performed as follows, after the soft baking step 6) of spin coating process, described herein:

[0111] UV-exposure (instrument) followed by post exposure bake on the hot plate (about 160°C for 2 min); Solvent development (RER 500 solution for 2.5 min and RER 600 solution for 2.5 min) followed by vacuum treatment for solvent removal (between about 1 to about 2 hours at pressure between about 0.5 to about 0.8 mbar);

[0112] Hard bake in oven (between about 180°C to about 200°C).

[0113]

[0086] The glass transition (Tg-value) is measured by removing with a blade a portion of the UV-VIS- curable composition applied, as described herein, on the silicon substrate, particularly a silicon wafer. The composition is removed and measured for each of the curing process steps, described herein, as well as the soft bake step 6) of the spin-coating process, described herein. The Tg-value is measured by means of DSC Perkin Elmer TAC 7 / DX By performing a ramp between 25°C and 190°C (rate 10°C / min). On the thermogram obtained for each measurement the Tg-value is determined by means of a DSC software. The reported Tg-value is for the last hard bake stage of the curing process.

[0114]

[0087] The optimum curing energy for the polymerization process is measured by means of FTIR spectrophotometric equipment, by monitoring conversion of epoxy moieties during the process at the characteristic frequency between 910cm-1and 920 cm-1. The FTIR conversion measurement is performed by processing the UV-VIS-curable composition on a blind silicon wafer. The substrate must be preferably made of silicon because the need of having transparency of the substrate towards the infrared radiation. The FTIR measurement is performed by means of Nexus Nicolet AES 9900215 equipment, for each of the curing process steps, described herein, as well as the soft bake step 6) of the spin-coating process, described herein.

[0115]

[0088] For ink resistance test, the compatibility of the print-heads with the experimental configurations with the inks is done by observing the shape of the microhydraulics under an IR microscope after storage (3 weeks, 5 weeks, and 7 weeks). The lack of swelling and deformation in the shape of the microhydraulics ensures good levels of print-head performance, inventive compositions In such a case, the UV-VIS-curable compositions were classified as ‘good’.

Claims

CLAIMS1 . A UV-VIS-curable composition comprising: a) about 20 to about 40 wt.% of at least one aromatic epoxide component, wherein the epoxy functionality is between 2 to 3; b) about 30 to about 50 wt.% of at least one cycloaliphatic epoxide component, b) being different than a); c) about 2 to about 20 wt.% of at least one ester-containing component; d) about 2 to about 12 wt.% of at least one fluorine-based component; e) about 1 to about 15 wt.% of at least one cationic photoinitiator; f) more than about 3 wt.% of at least one additive selected from the group consisting of surfactants and adhesion promoters or mixtures thereof; g) 0 to 5 wt.% of at least one photosensitizer; and wherein the composition has a Tg-value of less than 100 °C and a viscosity between about 1000 m Pas to about 4000 m Pas at 25 °C, wherein the weight percents are based on the total weight of the UV-VIS-curable composition.

2. The UV-VIS-curable composition according to claim 1 , wherein the Tg-value is less than 90 °C, preferably less than 80 °C.

3. The UV-VIS-curable composition according to claims 1 or 2 having a viscosity between about 1000 m Pas to about 3000 m Pas.

4. The UV-VIS-curable composition according to claims 1 to 3, wherein the component (a) is present in an amount between about 20 to about 30 wt.%, prerebaly between about 20 to about 25 wt.%, the weight percents being based on the total weight of the UV-VIS-curable composition.

5. The UV-VIS-curable composition according to claims 1 to 4, wherein the component (b) is present in an amount between about 30 to about 35 wt.%, the weight percents being based on the total weight of the UV-VIS-curable composition.

6. The UV-VIS-curable composition according to claims 1 to 5, wherein the component (c) is a cyclic ester, preferably caprolactone.

7. A UV-VIS-curable composition according to any one of the claims 1 to 6 wherein the component e) is selected from the group consisting of triphenylsulfonium salts, diazonium salts, diaryliodonium salts, ferrocenium salts, metallocene compounds and mixtures thereof.

8. A method for coating a silicon substrate, wherein the method comprises: a) providing a silicon substrate, in particular silicon wafer; b) depositing the UV-VIS-curable composition according to claims 1 to 7;c) rotationally spreading out said composition, in particular by spin-coating; d) at least partially, preferably completely, evaporating the solvent from said composition; e) applying a mask to the UV-VIS-curable composition to generate a photolithographic pattern; f) at least completely removing any uncured UV-VIS-curable composition; g) at least partially curing said composition.

9. An inkjet printhead comprising any of the UV-VIS-curable composition recited in any one of claims 1 to 7, in at least a partially cured state.

10. A method of manufacturing an inkjet printhead comprising the UV-VIS-curable compositions of any of the claims 1 to 7.

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