Epoxy-based UV-vis curable composition

Abstract

The present invention relates to a UV-VIS curable composition comprising: a) from about 20 to about 40 wt.% of at least one aromatic epoxide component wherein an epoxy functionality is between 2 and 3; b) from about 30 to about 50 wt.% of at least one cycloaliphatic epoxide component, b) being different from a); c) from about 2 to about 20 wt.% of at least one ester-containing component; d) from about 2 to about 12 wt.% of at least one fluorine-based component; e) from about 1 to about 15 wt.% of at least one cationic photoinitiator; f) greater 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 DEG C and a viscosity at 25 DEG C between about 1000 m-Pas and about 4000 m-Pas, wherein the weight percentages 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

TECHNICAL FIELD

[0001] The present invention relates to the technical field of UV-VIS curable compositions useful for manufacturing inkjet printheads, their use and the method of manufacturing inkjet printhead assemblies comprising the UV-VIS curable compositions. BACKGROUND

[0002] As described in patent EP 1896262 B1 (see therein the description of the Figure 1 ) or Figure 1 Typical inkjet printhead cartridges are made from a printhead firing assembly consisting of a printhead die bonded to a flexible printed circuit. The printhead silicon die, also called silicon jetor bank, incorporates electrical and hydraulic components to direct ink to each jetting site, energize it as needed to produce ink drops for printing. A nozzle plate is applied on the top surface of the die to provide nozzles for ink ejection. The whole firing assembly is then bonded to a cartridge containing an ink reservoir, closed by a lid. Suitable ink channels are present in the cartridge body to allow ink delivery to the printhead die and reach the microfluidic circuit either through channels machined in the die or from the die edge, depending on the printhead layout.

[0003] In the field of inkjet printing, using solvent-based and water-based ink formulations, the materials used for the protection of the electrical components and the definition of the micro-hydraulic components are generally epoxy or unsaturated resins. This material can be reacted by a UV-VIS curable process. The benefit of this process is the ability to control the degree of crosslinking of the composition.

[0004] One of the problems of the prior art is the defect in the manufacturing process of the silicon jetor bank. The jetor bank is composed of a CMOS part and a MEMS part. The CMOS unit is composed of a series of conductive and insulating layers used to manage electrical signals. The geometry of the resistors needed to generate the ink bubble is realized within the MEMS area. Different metal layers are needed to jet the ink, but the presence of layers of different thicknesses creates a topography that introduces different gaps between the silicon wafer and the nozzle plate. The crosslinking of the UV-VIS curable composition used to manufacture the inkjet printhead, in other words the shrinkage driven by the crosslinking and solvent evaporation process, does not exacerbate the gap problem, thereby impairing the protection and sealing of the interface once the orifice layer is thermally bonded to the micro-hydraulic components.

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

[0006] Furthermore, the UV-VIS curable composition should be compatible with various types of inks, i.e. water-based and solvent-based inks, since these are used. The UV-VIS curable composition should have a high resistance to chemicals and an appropriate mechanical flexibility for the application. Since the deposition of the UV curable composition on the silicon substrate is carried out by means of spin coating, the composition should have a normal viscosity value. SUMMARY

[0007] In a first aspect, the present invention relates to a UV-VIS curable composition comprising:

[0008] a) 20 to 40 wt.% of at least one aromatic epoxide component, wherein the epoxide functionality is between 2 and 3;

[0009] b) 30 to 50 wt.% of at least one cycloaliphatic epoxide component, b) being different from a);

[0010] c) 2 to 20 wt.% of at least one ester-containing component;

[0011] d) 2 to 12 wt.% of at least one fluorine-based component;

[0012] e) 1 to 15 wt.% of at least one cationic photoinitiator;

[0013] f) more than 3 wt.% of at least one additive selected from the group consisting of surfactants and adhesion promoters;

[0014] g) 0 to 5 wt.% of at least one photosensitizer; and

[0015] wherein the composition has a Tg value of less than 100 °C and a viscosity at 25 °C of between about 1000 m-Pas to about 4000 m-Pas, wherein the weight percentages are based on the total weight of the UV-VIS curable composition.

[0016] In a second aspect, the present invention relates to an inkjet printhead comprising the UV-VIS curable composition as described herein in an at least partially cured state.

[0017] In a third aspect, the present invention relates to a method of coating a silicon substrate, wherein the method comprises:

[0018] a) providing a silicon substrate, in particular a silicon wafer;

[0019] b) depositing the UV-VIS curable composition as described herein;

[0020] c) spin-wise spreading said composition, in particular by spin coating;

[0021] d) at least partially, preferably completely, evaporating the solvent from the composition;

[0022] e) applying a mask to the UV-VIS curable composition to produce a lithographic pattern;

[0023] f) at least completely removing any uncured UV-VIS curable composition;

[0024] g) at least partially curing the composition.

[0025] In a last aspect, the present application relates to the use of the UV-VIS curable composition described herein for the manufacture of the inkjet printhead described herein.

[0026] Surprisingly, it was found that the UV-VIS curable composition described herein provides at least the following advantages:

[0027] - after curing, a chemical resistance or stability to various inks, in particular to solvent-based inks;

[0028] - a good adhesion and wetting to various substrates of the inkjet printhead;

[0029] - a good thixotropy suitable for spin-coating application;

[0030] - a fast and efficient curing temperature and a compatibility with the performance of the manufacturing of high-speed printhead systems; and

[0031] - a lower amount of solvent required. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1A schematic view of an inkjet printhead cartridge (1) is shown. The cartridge (1) houses on its surface a printhead die (2) provided with a nozzle plate (3). The line B-B shown 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 means of electrical signals sent from the printer to the printhead die: for this purpose a flexible printed circuit (4) is used. Polyimide is commonly used for the flexible circuit substrate. A window is formed on the surface of the flexible printed circuit to allow the printhead die to protrude, whereby the flexible printed circuit surrounds the die. Conductive metal tracks of the flexible printed circuit protrude from the window edges to electrically contact the die as leads. Contact areas (5) are provided to electrically communicate with the printer on the other side of the flexible circuit. The electrical connection between the leads and the die is ensured by a suitable bonding process such as tape automated bonding (TAB). The die is provided with a plurality of bonding pads near the periphery to allow the bonding process, on its surface housing the leads: therefore, the pad surface must be freely accessible by the bonding tool without being covered by any layer until the bonding process is completed. Typically, although not in all cases, the pads are distributed near the short sides of the printhead die.

[0033] Figure 2 A cross-sectional view of the printhead die (2) and the flexible circuit is shown. The view is along a direction perpendicular to the line B-B. The die (2) is a silicon substrate having on its surface a conductive layer, a resistive layer, a dielectric layer and a protective layer, the die (2) being covered with a patterned barrier layer (6) on the basis of which the hydraulic printhead circuit with ejection chambers (7) is built. The barrier layer, typically a polymer, is covered by a nozzle plate (3) whose nozzles allow the ejection of ink droplets (8). Bonding pads (9) are placed near the die side housing the leads (10) protruding from the flexible printed circuit (4), the leads (10) being bonded to the pad surface. The leads are extensions of the conductive tracks (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 serves as an insulating protectant, preventing the conductive tracks (11) from being in mechanical or electrical contact with any part or material that could cause damage or short-circuit. A UV-VIS curable composition (not shown) is disposed between the silicon die (2) and the nozzle plate (3). DETAILED DESCRIPTION

[0034] DEFINITIONS

[0035] The following definitions are used to clarify the meaning of terms discussed in the specification and defined in the claims.

[0036] As used herein, the indefinite article "a" means one as well as more than one, and thus does not necessarily limit its specified noun to a single one.

[0037] As used herein, the term "about" means that the amount or value discussed can be the specified value or some other value in the vicinity of the specified value. The phrase is intended to convey that similar values to the recited value, within ±5% of the recited value, result in an equivalent outcome or effect according to the application.

[0038] As used herein, the term "UV-VIS" is intended to mean radiation having a wavelength component in the UV-VIS part of the electromagnetic spectrum; typically 200 nm to 420 nm.

[0039] As used herein, the term "at least one" means one or more than one, e.g. one or two or three.

[0040] As used herein, the term "and / or" means that either or both of the elements so conjoined can be present. As used herein, the term "and / or" means that either or both of the elements so conjoined can be present. For example, "A and / or B" shall mean either or both A and B can be present. In the instances of "only A", the term also encompasses the possibility that B is not present, i.e. "only A, but not B".

[0041] As used herein, the term "comprising" is intended to be non-exclusive and open-ended. Thus, for example, a UV-VIS curable composition comprising compound A can comprise other compounds than A. However, as a specific embodiment thereof, the term "comprising" also encompasses the more limiting meanings of "consisting essentially of and "consisting of, such that, for example, a UV-VIS curable composition "comprising A, B and optionally C" can also consist (essentially) of A and B, or (essentially) of A, B and C.

[0042] Where the specification refers to "preferred" embodiments / features, combinations of those "preferred" embodiments / features are also contemplated as being disclosed, as long as such combinations of "preferred" embodiments / features are technically meaningful.

[0043] The term "wt.%" means the amount of the component mentioned, based on the total weight of the UV-VIS curable composition.

[0044] When more than one component a) - g) is comprised in the UV-VIS curable composition described herein, the weight percentage refers to the total amount of the more than one component a) - g).

[0045] The present application relates to a UV-VIS curable composition comprising:

[0046] a) 20 to 40 wt.% of at least one aromatic epoxide component, wherein the epoxide functionality is between 2 and 3;

[0047] b) 30 to 50 wt.% of at least one cycloaliphatic epoxide component, b) being different from a);

[0048] c) 2 to 20 wt.% of at least one ester-containing component;

[0049] d) 2 to 12 wt.% of at least one fluorine-based component;

[0050] e) 1 to 15 wt.% of at least one cationic photoinitiator;

[0051] d) greater than 3 wt.% of at least one additive selected from the group consisting of surfactants and adhesion promoters or mixtures thereof;

[0052] g) 0 to 5 wt.% of at least one photosensitizer; and

[0053] wherein the composition has a Tg value of less than 100 °C and a viscosity at 25 °C between about 1000 m-Pas to about 4000 m-Pas,

[0054] wherein the weight percentages are based on the total weight of the UV-VIS curable composition.

[0055] The UV-VIS curable composition presents a Tg value of less than 100 °C. In a preferred embodiment, the Tg value is less than 90 °C, more preferably less than 80 °C. The Tg value plays an important role in the flexibility or deformability in the final step of the curing process applying high temperature (200 °C) as described herein. Without being bound by any particular theory, the optimal Tg value allows the cured composition to change conformation, thus the chains of the polymer to move freely. The reported Tg value is for the last hard bake stage of the curing process as described herein.

[0056] The UV-VIS curable composition presents a viscosity value at 25 °C between about 1000 m-Pas to about 4000 m-Pas, preferably between 2000 m-Pas to about 3500 m-Pas, the viscosity value being measured with a rotational viscometer Reologica with plate C40. Compositions with viscosity in these ranges provide the benefits as previously mentioned, particularly regarding their suitability for application by spin coating techniques in the manufacture of inkjet printheads.

[0057] The UV-VIS curable composition comprises at least one aromatic epoxide component (a) described herein, which is an aromatic epoxide monomer or an aromatic epoxide oligomer component or a mixture thereof. As used herein, aromatic epoxide monomer or aromatic epoxide oligomer means a component containing reactive or curable epoxy groups as well as aromatic moieties. The at least one aromatic epoxide monomer and aromatic epoxide oligomer can independently have an epoxy functionality (number of epoxy groups per molecule) of 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 of 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.%.

[0058] The aromatic epoxide monomer or aromatic epoxide oligomer can be derived from a mononuclear phenol, such as resorcinol or hydroquinone, or can be based on a polynuclear phenol, such as bis-(4-hydroxyphenyl)methane (bisphenol F), 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), or based on condensation products of phenol or cresol with formaldehyde under acidic conditions, commonly known as novolacs, in particular phenol novolacs and cresol novolacs.

[0059] Suitable commercially available aromatic epoxide monomers or aromatic epoxide oligomers are, but not limited to: ARALDITE ® GY series, which are bisphenol A epoxy liquid resins; ARALDITE ® CT and GT series, which are bisphenol A epoxy solid resins; ARALDITE ® GY and PY series, which are bisphenol F epoxy liquids; ARALDITE ® ECN series of epoxy cresol novolacs; ARALDITE ® EPN series of epoxy phenol novolacs; DEN series of epoxy novolac resins available from Palmer Holland.

[0060] In one embodiment, the UV-curable composition comprises at least one component described herein having ester functionality (i.e., ester-containing component) c). The ester- containing component can be used as a (reactive) solvent in addition to any other solvent that can be added to the UV-VIS curable composition. The ester-containing component can be any suitable ester, such as acyclic esters or even preferably cyclic esters. The component having ester functionality can have additional functional groups so long as the additional functional groups do not interfere with the UV-VIS curable composition in an adverse manner. The component having ester functionality can be present in an amount of about 2 to about 20 wt.%, preferably about 15 to about 20 wt.%. Without being bound by any particular theory, it is believed that the solvent having ester functionality participates in a transesterification reaction with the aromatic epoxide oligomer or monomer component a) and during this reaction, the solvent bonds with component a).

[0061] Suitable ester-containing components include, but are not limited to, benzyl benzoate, bis(2-ethylhexyl) adipate, bis(2-ethylhexyl) phthalate, bis(2-ethylhexyl) terephthalate, 2-butoxyethanol acetate, butyl acetate, sec-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, 6-hydroxyhexanoic acid ethyl ester.

[0062] Suitable cyclic esters include, but are not limited to, ε-caprolactone, such as β-methyl-δ-valerolactone, δ-valerolactone, ε-caprolactone, 2-methyl-ε-caprolactone, 3-methyl-ε- caprolactone, 4-methyl-ε-caprolactone, 5-tert-butyl-ε-caprolactone, 7-methyl-ε- caprolactone, 4,4,6-ε-caprolactone, trimethyl-ε-caprolactone, 4,6,6-trimethyl-ε- caprolactone, or mixtures thereof.

[0063] In one embodiment, the UV-curable composition comprises at least one component described herein having at least one fluorine atom (i.e., fluorine-based component) d). The fluorine- based component is present in an amount of about 2 to about 12 wt.%, preferably about 5 to about 11 wt.%. The fluorine-based component is different from the other components included in the UV-VIS curable composition.

[0064] In preferred embodiments, the fluorine-based component contains multiple, i.e. more than one, fluorine atoms as well as other functional groups, preferably hydroxyl groups (-OH). 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, 1H,1H,3H-hexafluorobutanol, 2H-hexafluoro-2-propanol, 1H,1H,7H-dodecafluorohexanol, 1H,1H,3H-tetrafluoropropanol, 6-(perfluoro-1-methoxyethyl)hexanol, 1H,1H-2,5-bis(trifluoromethyl)-3,6-dioxadodecafluorononanol, 6-(perfluorohexyl)hexanol, 3-(perfluorohexyl)propanol, 2-(perfluorohexyl)ethanol, 2-perfluoropropoxy-2,3,3,3-tetrafluoropropanol, 6-(perfluorobutyl)hexanol, 3-(perfluorobutyl)propanol, 2-(perfluorobutyl)ethanol, 1H,1H-heptafluorobutanol, 6-(perfluoroethyl)hexanol, 1H,1H-pentafluoropropanol, 1H,1H-trifluoroethanol.

[0065] Even more preferred examples of fluorine-based components 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.

[0066] The UV-VIS curable composition comprises at least one cationic photoinitiator e) described herein in an amount of 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 preferably is selected from the group consisting of (di)nitrogen onium salts, oxygen onium salts, (diaryl)iodonium salts, sulfonium salts and mixtures thereof, more preferably selected from the group consisting of oxygen onium salts, iodonium salts, sulfonium salts and mixtures thereof, still more preferably selected from the group consisting of iodonium salts, sulfonium salts and mixtures thereof.

[0067] The iodonium salts described herein have a cationic part and an anionic part, wherein the anionic part is preferably BF4 - , B(C6F5)4 - , PF6 - , AsF6 - , SbF6 - or CF3SO3 -more preferably SbF6 - or PF6 - and wherein the cationic moiety is preferably an aromatic iodonium ion, more preferably an iodonium ion comprising two aryl groups, wherein the two aryl groups can independently be substituted with one or more alkyl groups (e.g. methyl, ethyl, isobutyl, tert-butyl, etc.), one or more alkoxy groups, one or more nitro groups, one or more halogen containing groups, one or more hydroxyl groups, or a combination thereof. Particularly suitable examples of iodonium salts for use in the present application are commercially available from IGM Resins under the names Omnicat 250 and 440 and from Lambson under the name SpeedCure 938.

[0068] The sulfonium salts described herein have a cationic moiety and an anionic moiety, wherein the anionic moiety is preferably BF4 - , B(C6F5)4 - , PF6 - , (PF 6-m (C n F2n-1) m ) - (wherein m is an integer from 1 to 5 and n is an integer from 1 to 4), AsF6 - , SbF6 - , CF3SO3 - , a perfluoroalkylsulfonate or pentafluorohydroxyantimonate, more preferably SbF6 - or PF6 - 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 can independently be substituted with one or more alkyl groups (e.g. methyl, ethyl, isobutyl, tert-butyl, etc.), one or more alkoxy groups, one or more aryloxy groups, one or more halogen containing groups, one or more hydroxyl groups, or a combination thereof.

[0069] Suitable examples of sulfonium ions comprising two or more aryl groups include, but are not limited to, triaryl sulfonium ions, diphenyl [4-(phenylthio)phenyl] sulfonium ions, bis[4-(diphenylsulfonio)phenyl] sulfonium ions, triphenyl sulfonium ions, and tris[4-(4-acetylphenyl) sulfanylphenyl] sulfonium ions.

[0070] In a preferred embodiment, the at least one cationic photoinitiator e) is selected from the group consisting of triphenyl sulfonium salts, diazonium salts, diaryliodonium salts, ferrocenium salts, metallocene compounds, and mixtures thereof.

[0071] Suitable commercially available cationic photoinitiators e) are, but not limited to, Irgacure PAG 290 (BASF), diphenyl iodonium hexafluorophosphate (Sigma-Aldrich), diphenyl iodonium hexafluoroantimonate (Sigma-Aldrich), triarylsulfonium hexafluorophosphate (Sigma Aldrich) and / or triphenylsulfonium triflate (Sigma-Aldrich), aromatic iodonium and sulfonium salts, such as triarylsulfonium hexafluorophosphate (CYRACURE UVI-6992, Dow Chemical Company), triarylsulfonium hexafluoroantimonate (CYRACURE UVI-6976, Dow Chemical Company) and arylsulfonium hexafluorophosphate (ESACURE 1064, Lamberti). Triphenylsulfonium hexafluorophosphate (ESACURE 1064, Lamberti), glycidyl ether solution of bis-(4-dodecylphenyl) iodonium hexafluoroantimonate (SpeedCure 937), bis-(4-tert-butylphenyl)- iodonium hexafluorophosphate (SpeedCure 938), bis-(4-tert-butylphenyl)-iodonium hexafluorophosphate (SpeedCure 939), propylene carbonate solution of (sulfanediyl diphen-4,1-diyl) bis(diphenylsulfonium) bis(hexafluoroantimonate) (SpeedCure 976), propylene carbonate solution of (sulfanediyl diphen-4,1-diyl) bis(diphenylsulfonium) bis(hexafluoroantimonate) (SpeedCure 992) available from Arkema, diphenyl [(phenylthio)phenyl] sulfonium (PAG-20001), mixed triarylsulfonium hexafluoroantimonate PAG-20002 or PAG-21608 available from Aalchem. TM UVI-6992, Dow Chemical Company), triarylsulfonium hexafluoroantimonate (CYRACURE TM UVI-6976, Dow Chemical Company) and arylsulfonium hexafluorophosphate (ESACURE 1064, Lamberti). Triphenylsulfonium hexafluorophosphate (ESACURE 1064, Lamberti), glycidyl ether solution of bis-(4-dodecylphenyl) iodonium hexafluoroantimonate (SpeedCure 937), bis-(4-tert-butylphenyl)- iodonium hexafluorophosphate (SpeedCure 938), bis-(4-tert-butylphenyl)-iodonium hexafluorophosphate (SpeedCure 939), propylene carbonate solution of (sulfanediyl diphen-4,1-diyl) bis(diphenylsulfonium) bis(hexafluoroantimonate) (SpeedCure 976), propylene carbonate solution of (sulfanediyl diphen-4,1-diyl) bis(diphenylsulfonium) bis(hexafluoroantimonate) (SpeedCure 992) available from Arkema, diphenyl [(phenylthio)phenyl] sulfonium (PAG-20001), mixed triarylsulfonium hexafluoroantimonate PAG-20002 or PAG-21608 available from Aalchem.

[0072] Further examples of useful photoinitiators 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”, 2ndEdition, J. V. Crivello & K. Dietliker, Edited by G. Bradley, jointly published by John Wiley & Sons and SITA Technology Limited in 1998.

[0073] The UV-VIS curable composition comprises at least one cycloaliphatic epoxide component b), wherein the at least one cycloaliphatic epoxide component b) is different from component a) and other components added to the UV-VIS curable composition.

[0074] The cycloaliphatic epoxide components described herein can be di- or multifunctional. Preferably, the cycloaliphatic epoxide components independently comprise at least one cyclohexane group and at least two epoxide groups. Preferred cycloaliphatic epoxides comprise more than one cyclohexane epoxide group and have structural formula (I):

[0075]

[0076] (I)

[0077] wherein X is selected from the group consisting of a single bond and a divalent radical comprising more than one atom.

[0078] According to one embodiment, X is a divalent hydrocarbon radical which is a straight chain or branched alkylene radical comprising 1 to 18 carbon atoms, wherein examples of the straight chain or branched alkylene radical include, but are not limited to, methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene.

[0079] According to one embodiment, X is a divalent cycloaliphatic hydrocarbon radical or cycloalkylene radical, such as 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, and cyclohexylene.

[0080] According to one embodiment, X is a divalent radical comprising more than one oxygen-containing linking group, which oxygen-containing linking group is -CO-, -O-CO-O-, -COO-, and -O-. According to one embodiment, preferred epoxide derivatives having structural formula (I) wherein X is a divalent radical comprising more than one oxygen-containing linking group, which oxygen-containing linking group is -CO-, -O-CO-O-, -COO-, -O-, comprise structural formula (II), (III), or (IV):

[0081]

[0082] (II)

[0083] cyclohexylmethyl-3,4-epoxycyclohexane carboxylate, 3,4-epoxy-6-methyl- cyclohexylmethyl-3,4-epoxy-6-methylcyclohexane carboxylate, 3,4-epoxy-2- methyl-cyclohexylmethyl-3,4-epoxy-2-methylcyclohexane carboxylate, and 3,4- epoxy-4-methyl-cyclohexylmethyl-3,4-epoxy-4-methylcyclohexane carboxylate;

[0084]

[0085] (III)

[0086] cyclohexylmethyl-3,4-epoxycyclohexane carboxylate, 3,4-epoxy-6-methyl- cyclohexylmethyl-3,4-epoxy-6-methylcyclohexane carboxylate, 3,4-epoxy-2- methyl-cyclohexylmethyl-3,4-epoxy-2-methylcyclohexane carboxylate, and 3,4- epoxy-4-methyl-cyclohexylmethyl-3,4-epoxy-4-methylcyclohexane carboxylate;

[0087]

[0088] (IV)

[0089] wherein R1-R9 are independently hydrogen or a linear or branched hydrocarbon residue containing 1 to 3 carbon atoms; preferred examples of cycloaliphatic diepoxides having structural formula (IV) are 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4- epoxy) cyclohexane-m-dioxane.

[0090] According to one embodiment, the cycloaliphatic epoxide component described herein has structural formula (V) or (VI):

[0091]

[0092] (V)

[0093]

[0094] (VI)

[0095] The alicyclic epoxide components described herein may be hydroxyl-modified or (meth)acrylate-modified. Examples are from Daicel Corp. under the names Cyclomer A400 (CAS: 64630-63-3) and Cyclomer M100 (CAS: 82428-30-6), from TetraChem / Jiangsu under the names TTA 15 and TTA 16, from Daicel under the name Celloxide 2021P, and from Dow Chemical under the name CYRACURE. TM 6110 UVR, CYRACURE TM It is commercially available from Sigma Aldrich under the name 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexane carboxylate, or from PHLEXTEK as ACHWL CER 4221, or from Arkema under the name 7-oxabicyclo[4.1.0]hept-3-ylmethyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate (UviCure S105).

[0096] The UV-VIS curable composition may contain at least one filler. The filler may 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 in an amount of about 20 to about 25 wt.%. In a preferred embodiment, the filler has a refractive index of about 1.2 to about 1.8 at 400 nm, 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.

[0097] The refractive index of at least one filler can be measured using ISO 489:2022, while the particle size can be determined using laser diffraction methods according to ISO 13320:2020. Furthermore, the refractive indices of various materials can also be obtained from refractiveindex.info.

[0098] The inorganic filler can preferably be selected from the group consisting of carbon fibers, talc, mica (muscovite), wollastonite, calcinated 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 can be selected from the group consisting of glass, carbonates, talc and mixtures thereof. A particularly preferred inorganic filler is talc.

[0099] Preferably, the filler is an organic filler. The organic filler can be selected from the group consisting of acrylic resins produced at least from acrylate or methacrylate, copolymers thereof with styrene (i.e. styrene-acrylic resins), modified rosin resins, terpene resins, modified terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral, polyol polyacrylate, polyvinyl alcohol, polyurethane, hydrogenated petroleum resins and mixtures thereof. Advantageously, polymeric acrylic resins based on PMMA (poly(methyl methacrylate)), PMMA-DEGDA (poly(methyl methacrylate)-diethylene glycol dimethacrylate), PBMA (poly(butyl methacrylate)) and PiBMA (poly(isobutyl methacrylate)) are preferred. Other suitable resins are crosslinked poly(styrene-co-divinylbenzene) or poly(4-vinylpyridine-co-ethylvinylbenzene). In preferred embodiments, the organic polymeric filler has a particle size of < 10 pm. When the filler has a particle size as described herein, its compatibility in the UV-VIS curable composition is improved and the composition maintains high uniformity upon dispensing as well as form or shape stability. From the point of view of chemical robustness and / or stability over time, the acrylic resins impart the desired rheological properties without inducing any weaknesses in the composition.

[0100] According to preferred embodiments, the UV-VIS curable composition can comprise one or more oxetane compounds or compounds having oxetane functionality as described herein. For embodiments wherein the UV-VIS curable composition described herein comprises one or more oxetanes, the one or more oxetanes are present in an amount less than or equal to about 30 wt.%, preferably greater than or equal to about 5 wt.% and less than or equal to about 25 wt.%.

[0101] Preferred examples of oxetanes include trimethylene oxide, 3,3-dimethyloxetane, trimethylolpropaneoxetane, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-[(2- ethylhexyloxy)methyl]oxetane, 3,3-dicyclohexyloxetane, 3-ethyl-3- phenoxymethyloxetane, bis([l-ethyl(3-oxetanylyl)]methyl)ether, 1,4- bis[3-ethyl-3-oxetanylmethoxy)methyl]benzene, 3,3-dimethyl-2(p- methoxy-phenyl)-oxetane, 3-ethyl-[(tri-ethoxysilylpropyloxy)methyl]oxetane, 4,4-bis(3-ethyl-3-oxetanylyl)methoxymethyl]biphenyl, and 3,3-dimethyl-2(p- methoxy-phenyl)oxetane. One or more of the oxetanes described herein can be hydroxyl-modified or (meth)acrylate-modified.

[0102] Suitable commercially available examples of oxetanes are, but are 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).

[0103] The UV-VIS curable composition can comprise at least one photosensitizer g) described herein. The photosensitizer is activated by one or more wavelengths emitted by the UV-VIS light source and reaches an excited state. The excited photosensitizer then transfers energy to the at least one cationic photoinitiator, which in turn initiates the polymerization process. The at least one photosensitizer is preferably present in an amount of about 0 to about 5 wt.%, more preferably about 0.2 to about 1 wt.%.

[0104] Commercially available photosensitizers are, but are not limited to, thioxanthone derivatives, anthracene derivatives (such as 9,10-dimethylanthracene sold as ® UVS-1101, 9,10-diethoxyanthracene, and as ANTHRACURE®UVS-1331, 9,10- dibutoxyanthracene, both sold by Kawasaki Kasei Chemicals Ltd) and titanocene derivatives (such as Irgacure®819, Irgacure®907, and Irgacure®784, all sold by BASF). ® UVS-1101, 9,10-diethoxyanthracene, and as ANTHRACURE®UVS-1331, 9,10- dibutoxyanthracene, both sold by Kawasaki Kasei Chemicals Ltd) and titanocene derivatives (such as Irgacure®819, Irgacure®907, and Irgacure®784, all sold by BASF). ®784). 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, the thioxanthone-based photosensitizer can be used in oligomeric or polymeric form (such as OMNIPOL TX sold by IGM Resins, Genopol TX-2 sold by Rahn, or SpeedCure 7010 sold by Lambson). *® TX-2 or SpeedCure 7010 sold by Lambson).

[0105] The UV-VIS curable composition can 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 components a) to g), and wherein the amount of the 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.%.

[0106] In one embodiment, the at least one additive is a non-ionic surfactant, and the UV-VIS curable composition can comprise one or more of the non-ionic surfactants in an amount of 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.%, other additional additives, such as adhesion promoters, are added at least in an amount required to make the total amount of additives greater than 3 wt.%.

[0107] As well known to those skilled in the art, non-ionic surfactants contain both hydrophilic and hydrophobic parts and are not charged. Preferably, 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 epoxy groups. More preferably, one or more non-ionic surfactants are selected from non-ionic fluorinated surfactants and non-ionic silicone surfactants.

[0108] As used herein, the term "non-ionic fluorinated surfactant" includes non-ionic perfluoropolyether surfactants and non-ionic fluorosurfactants.

[0109] As used herein, the term "non-ionic perfluoropolyether surfactant" means 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 groups, preferably from the group consisting of hydroxyl and epoxide. Preferably, the non-ionic perfluoropolyether surfactant is characterized by an average molecular weight (M n) below about 2000 [g / mol]. As used herein, perfluoropolyether backbone denotes the residue of a perfluoropolyether polymer comprising a random distribution of repeating units selected from perfluoromethyleneoxy (-CF2O-) and perfluoroethyl enoxy (-CF2-CF2O-). The perfluoropolyether residue is attached to the terminal functional group directly or via a spacer selected from methylene(oxy ethylene), 1,1 -difluoro ethylene-(oxy ethylene), methylene-di(oxy ethylene), 1,1 -difluoro ethylene-di(oxy ethylene), methylene-tri(oxy ethylene), 1,1 -difluoro ethylene-tri(oxy ethylene), methylene-tetra(oxy ethylene), 1,1 -difluoro ethylene-tetra(oxy ethylene), methylene-penta(oxy ethylene), 1,1 -difluoro ethylene-penta(oxy ethylene), 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.

[0110] Particularly suitable examples of non-ionic perfluoropolyether surfactants are the Fluorolink® E-series and Fluorolink® MD-series available from Solvay. ® Fluorolink® E10H, Fluorolink® MD700, Fluorolink® MD500, Fluorolink® AD1700, Fluorolink® S10, and Fluorolink® S20 are commercially available from Solvay. ® Fluorolink® E-series and Fluorolink® MD-series available from Solvay. ® Fluorolink® E-series and Fluorolink® MD-series available from Solvay. ® Fluorolink® E-series and Fluorolink® MD-series available from Solvay. ® Fluorolink® E-series and Fluorolink® MD-series available from Solvay. ® Fluorolink® E-series and Fluorolink® MD-series available from Solvay.

[0111] 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 (M n ) of from about 200 [g / mol] to about 2000 [g / mol]. Preferably, the non-ionic fluorosurfactant is a compound of general formula (VII):

[0112] CF3(CF2) x (CH2) y E

[0113] (VII)

[0114] wherein,

[0115] x is an integer from 2 to 18;

[0116] y is an integer from 0 to 8; and

[0117] E is selected from

[0118] , , , -(CR2CR2O) z H,

[0119] and -OSi(OR 20 )3,

[0120] wherein z is an integer from 0 to 15;

[0121] R can be the same or different at each occurrence and is selected from the group consisting of hydrogen and methyl; and

[0122] R 20 is C1-C4 alkyl.

[0123] The non-ionic fluorosurfactant can be selected from the group of fluorinated epoxy monomers, preferably selected from the group of 3-perfluorooctyl-1,2-epoxypropane (Fluorochem), 3-perfluorohexyl-1,2-epoxypropane (Sigma-Aldrich) (Chemical Co., Ltd) and / or 3-[2-(perfluorohexyl)ethoxy]-1,2-epoxypropane (TCI American).

[0124] Particularly preferred is a non-ionic fluorosurfactant of general formula (VIII-a):

[0125] CF3(CF2) x (CH2) y (CR2CR2O) z H

[0126] (VIII-a)

[0127] wherein,

[0128] x is an integer from 2 to 18;

[0129] y is an integer from 0 to 8; and

[0130] z is an integer from 0 to 15; and

[0131] R may be the same or different each time it appears, and is selected from hydrogen and methyl, preferably hydrogen. The nonionic fluorinated surfactant of general formula (VIII-a) is commercially available under the names CHEMGUARD S550-100 or CHEMGUARD S550, CHEMGUARD S222N, CHEMGUARD S559-100 or CHEMGUARD S559, all purchased from CHEMGUARD; under the name Capstone TM FS-31, Capstone TM FS-35, Capstone TM FS-34, Capstone TM FS-30, Capstone TM The FS-3100 is commercially available, and all of it was purchased from Chemours.

[0132] Nonionic fluorinated surfactants of general formula (VIII-b) are also preferred:

[0133] CF3 (CF2) x (CH2) y OSi(OR 20 )

[0134] (VIII-b),

[0135] in,

[0136] x is an integer from 2 to 18;

[0137] y is an integer from 0 to 8; and

[0138] R 20 It is a C1-C4 alkyl group. Nonionic fluorinated surfactants of general formula (VIII-b) are commercially available from Evonik under the names Dynasylan F8261 and Dynasylan F8263.

[0139] Nonionic fluorinated surfactants of general formula (VIII-c) are also preferred:

[0140]

[0141] (VIII-c),

[0142] in,

[0143] x is an integer from 2 to 18;

[0144] y is an integer from 0 to 8; and

[0145] R 21selected from the group consisting of hydrogen and methyl. Examples of non-ionic 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).

[0146] As used herein, non-ionic silicone surfactant refers to a non-ionic surfactant comprising a silicone backbone comprising randomly distributed repeating units selected from the group consisting of di(methyl)siloxane (— (CH3)2SiO— ) and / or methyl-(C2-C10-alkyl)-siloxane (— (CH3)(C2-C10-alkyl)SiO— ), wherein one or more methyl and / or C2-C10-alkyl groups can independently of each other be substituted with aryl; a polyester, optionally bearing a terminal functional group selected from the group consisting of hydroxyl, epoxide, and (meth)acrylate; a polyether, such as a polyalkylene glycol, including polyethylene glycol and polypropylene glycol, optionally bearing a terminal functional group selected from the group consisting of hydroxyl, epoxide, and (meth)acrylate; a hydroxyl group; an epoxy group; or a (meth)acrylate group; and / or wherein the silicone backbone can be attached to a terminal functional group selected from the group consisting of hydroxyl, epoxy, and (meth)acrylate groups, directly or via a spacer. The silicone backbone described herein can be attached to a urethane acrylate or fluoro-urethane acrylate. Preferably, the non-ionic silicone surfactant is characterized by an average molecular weight of below about 3000 g / mol. 10 — (CH3)(C2-C10-alkyl)SiO— ), wherein one or more methyl and / or C2-C10-alkyl groups can independently of each other be substituted with aryl; a polyester, optionally bearing a terminal functional group selected from the group consisting of hydroxyl, epoxide, and (meth)acrylate; a polyether, such as a polyalkylene glycol, including polyethylene glycol and polypropylene glycol, optionally bearing a terminal functional group selected from the group consisting of hydroxyl, epoxide, and (meth)acrylate; a hydroxyl group; an epoxy group; or a (meth)acrylate group; and / or wherein the silicone backbone can be attached to a terminal functional group selected from the group consisting of hydroxyl, epoxy, and (meth)acrylate groups, directly or via a spacer. The silicone backbone described herein can be attached to a urethane acrylate or fluoro-urethane acrylate. Preferably, the non-ionic silicone surfactant is characterized by an average molecular weight of below about 3000 g / mol. 10 — (CH3)(C2-C10-alkyl)SiO— ), wherein one or more methyl and / or C2-C10-alkyl groups can independently of each other be substituted with aryl; a polyester, optionally bearing a terminal functional group selected from the group consisting of hydroxyl, epoxide, and (meth)acrylate; a polyether, such as a polyalkylene glycol, including polyethylene glycol and polypropylene glycol, optionally bearing a terminal functional group selected from the group consisting of hydroxyl, epoxide, and (meth)acrylate; a hydroxyl group; an epoxy group; or a (meth)acrylate group; and / or wherein the silicone backbone can be attached to a terminal functional group selected from the group consisting of hydroxyl, epoxy, and (meth)acrylate groups, directly or via a spacer. The silicone backbone described herein can be attached to a urethane acrylate or fluoro-urethane acrylate. Preferably, the non-ionic silicone surfactant is characterized by an average molecular weight of below about 3000 g / mol.

[0147] Non-ionic silicone surfactants include, but are not limited to, poly-methyl-alkyl-siloxanes such as BYK-077 and BYK-085 available from BYK; polyester-modified poly-dimethyl-siloxanes such as BYK 310 available from BYK; polyether-modified poly-dimethyl-siloxanes such as BYK-377, BYK-333, BYK-345, BYK-346, and BYK-348 available from BYK; polyester-modified poly-methyl-alkyl-siloxanes such as BYK-315 available from BYK; polyether-modified poly-methyl-alkyl-siloxanes such as BYK-341, BYK-320, and BYK-325 available from BYK; hydroxyl-functional poly-dimethyl-siloxanes such as TEGOMER H-40 available from Evonik; and mixtures thereof. ®HSI-2311; polyester-modified, hydroxy-functional poly-dimethyl-siloxanes such as BYK-370 and BYK-373 available from BYK; polyether-modified, hydroxy-functional polydimethylsiloxanes such as BYK-308 available from BYK; polyether polyester-modified, hydroxy-functional polydimethylsiloxanes such as BYK-375 available from BYK; epoxy-functional poly-dimethyl-siloxanes such as TEGOMER H-Si 2330 available from Evonik ® E-Si 2330; acryloyloxy-functional poly-dimethyl-siloxanes such as TEGOMER H-Si 2330 available from Evonik ® V-SI 2250 and TEGO ® Rad 2700; polyester-modified, acryl-functional polydimethyl-siloxanes such as BYK-371 available from BYK; polyether-modified, acryl-functional polydimethyl-siloxanes such as TEGO Rad 2100 and TEGO ® Rad 2700; polyester-modified, acryl-functional polydimethyl-siloxanes such as BYK-371 available from BYK; polyether-modified, acryl-functional polydimethyl-siloxanes such as TEGO Rad 2100 and TEGO ® Rad 2500; silicone-modified, aliphatic urethane acrylates such as SUO-S3000 and SUO-S600NM available from Polygon; silicone and fluorine-modified, aliphatic urethane acrylates such as SUO-FS500 available from Polygon.

[0148] In another embodiment, the at least one additive is an adhesion promoter, and the UV-VIS curable composition can include more than one of the adhesion promoter. The adhesion promoter can be present at about 0.01 to about 0.1 wt.%, preferably about 0.02 to about 0.05 wt.%. The more than one adhesion promoter that can be used to further improve the adhesion of the resulting photopolymer layer can include a transition metal chelate, a mercaptan, a thiol-containing compound, a carboxylic acid, an organic phosphoric acid, a glycol, an alkoxysilane, a combination of alkoxysilane and hydroxy-functional polyorganosiloxane, or combinations thereof. The more than one adhesion promoter can be an unsaturated or an epoxy-functional compound. Suitable epoxy-functional compounds are known in the art and are commercially available, see, for example, U.S. Patent Nos. 4,087,585; 5,194,649; 5,248,715; and 5,744,507 column 45.

[0149] More than one adhesion promoter can preferably comprise an unsaturated or epoxy functional alkoxysilane. Examples of suitable epoxy functional alkoxysilanes include 3- glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, (epoxycyclohexyl)ethyl dimethoxysilane, (epoxycyclohexyl)ethyl diethoxysilane, and combinations thereof. Examples of suitable unsaturated alkoxysilanes include vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hexenyltrimethoxysilane, undecenyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltriethoxysilane, and combinations thereof.

[0150] Preferred adhesion promoters are preferably selected from the group comprising Silquest A187 (Momentive), (3-glycidoxypropyl)triethoxysilane (Sigma-Aldrich), (3- glycidoxypropyl)trimethoxysilane (Sigma-Aldrich), and / or trimethoxy[2-(7-oxabicyclo[4.1.0]heptan-3-yl)ethyl]silane (Sigma-Aldrich).

[0151] In addition to the above-mentioned components having ester functionality, the UV-VIS curable composition can comprise one or more other organic solvents. The one or more organic solvents are not particularly limited, but are preferably non-polar organic solvents. Examples of polar organic solvents include, but are not limited to, alcohols (e.g., methanol, ethanol, propanol, butanol, isopropanol, and fluorinated alcohols), ketones (e.g., acetone, methyl ethyl ketone, and cyclohexanone), carboxylates (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 can be used individually or in combination. The UV-VIS curable composition can contain up to about 10 wt.% of one or more organic solvents. Preferably, and when present, the one or more organic solvents are present in a total 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 composition is free of any solvent, i.e., it is solvent-free.

[0152] In another embodiment, the present application relates to a method of coating a silicon substrate, wherein the method comprises:

[0153] a) providing a silicon substrate, in particular a silicon wafer;

[0154] b) depositing a UV-VIS curable composition according to claims 1 to 7;

[0155] c) spreading the composition rotationally, in particular by spin coating;

[0156] d) at least partially, preferably completely, evaporating the solvent from the composition;

[0157] e) applying a mask to the UV-VIS curable composition to create a lithographic pattern;

[0158] f) at least completely removing any uncured UV-VIS curable composition;

[0159] g) at least partially curing the composition.

[0160] The masking step can be performed by any commercially available high precision mask aligner for (photo)lithography applications. An example of such a mask aligner is the model 170542 (Nr: 712) from Karl Suss KG Gmbh & Co. In this system, the mask and the silicon substrate, preferably a silicon wafer, are in contact for about 30 seconds. The material of the mask is quartz with a chromium pattern. The UV radiation is reflected on the chromium pattern, but passes through the quartz, thereby creating a lithographic pattern. An alternative non-contact method, in which contact with the silicon substrate is avoided, can be performed by means of a device such as an Ultratech Saturn Spectrum III stepper.

[0161] The removal of any uncured or uncrosslinked UV-VIS curable composition can be performed by means of spraying using a suitable solvent. In case spraying is performed, then a suitable vacuum system can be used to remove the solvent.

[0162] One embodiment relates to the use of the UV-VIS curable composition described herein for the manufacture of an inkjet print head.

[0163] Another embodiment relates to an inkjet print head comprising a UV-VIS curable composition as described herein in at least partially cured state.

[0164] The person skilled in the art can conceive several modifications to the above described specific embodiments without departing from the spirit of the present invention. These modifications are included in the present invention.

[0165] Furthermore, all documents mentioned throughout this specification are incorporated herein by reference in their entirety as if fully set forth.

[0166] Examples

[0167] Examples E1-E9 were prepared as follows. The individual ingredients were introduced into a suitable reaction vessel in the order listed in Table 1 from top to bottom. The materials were mixed in a Thinky planetary mixer for 5 cycles of 30 minutes each. After mixing, the resulting composition was introduced into a syringe for dispensing.

[0168] Viscosity measurements: were performed by means of a rotational viscometer Reologica with plate C40 (about 0.2 cm 3 The samples were performed.

[0169] Table 1

[0170]

[0171] Table 2

[0172]

[0173] - not tested

[0174] The spin coating process on silicon substrates, in particular silicon wafers, was performed by means of a Laurell-WS 400BZ-6NPP / LITE apparatus by the following steps:

[0175] 1. Set the spin coating conditions (usually the following were used: 20 s at 250 rpm, 20 s at 500 rpm or 60 s at 3900 rpm, depending on the viscosity of the UV-VIS curable composition);

[0176] 2. Place the silicon wafer on the instrument;

[0177] 3. Add about 12 mL of the UV-VIS curable composition onto the silicon substrate;

[0178] 4. Set the vacuum on the instrument to adhere the silicon substrate with the UV-VIS curable composition to the instrument;

[0179] 5. Press run;

[0180] 6. Soft bake on a hot plate (about 160 °C for 30 minutes).

[0181] After the soft bake step 6) of the spin coating process described herein, the curing process of the UV-VIS curable composition can be performed as follows:

[0182] - UV exposure (instrument) followed by post exposure bake on a hot plate (about 160 °C for 2 minutes);

[0183] - Solvent development (RER 500 solution for 2.5 minutes and RER 600 solution for 2.5 minutes) followed by vacuum treatment to remove the solvent (at a pressure of about 0.5 to about 0.8 mbar for about 1 to about 2 hours);

[0184] - Hard bake in an oven (between about 180 °C to about 200 °C).

[0185] The glass transition (Tg value) is measured by removing a part of the UV-VIS curable composition as described herein applied on a silicon substrate, in particular a silicon wafer, with a blade. The composition is removed and measured for each of the curing process steps described herein and for each of the soft baking steps 6) of the spin coating process described herein. The Tg value is measured by means of a DSC Perkin Elmer TAC 7 / DX by performing a temperature 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 the DSC software. The reported Tg value is that of the last hard baking stage of the curing process.

[0186] The optimal curing energy of the polymerization process is measured by monitoring the conversion of the epoxy moieties during the process by means of FTIR spectrophotometric equipment at the characteristic frequencies between 910 cm -1 and 920 cm -1 The FTIR conversion measurement is performed by processing the UV-VIS curable composition on a blind silicon wafer. As the substrate needs to be transparent to the infrared radiation, the substrate has to be made of silicon, preferably. The FTIR measurement is performed by means of a Nexus Nicolet AES 9900215 equipment for each of the curing process steps described herein and for each of the soft baking steps 6) of the spin coating process described herein.

[0187] For the ink resistance test, the compatibility of the printhead with the ink with the experimental configuration is performed by observing the shape of the micro-hydraulic components under an IR microscope after storage (3 weeks, 5 weeks and 7 weeks). The absence of swelling and deformation of the shape of the micro-hydraulic components ensures a good level of performance of the printhead. The composition of the application in this case, the UV-VIS curable composition, is classified as "good".

Claims

1. 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 and 3; b) about 30 to about 50 wt.% of at least one alicyclic epoxide component, b) being different from a); c) About 2 to about 20 wt.% of at least one ester-containing component; d) At least one fluorinated component, ranging from about 2 to about 12 wt.%; 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 The composition described herein has a Tg value of less than 100°C and a viscosity at 25°C between about 1000 mPas and about 4000 mPas. The weight percentages 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 claim 1 or 2, wherein the viscosity is between about 1000 mPas and about 3000 mPas.

4. The UV-VIS curable composition according to claims 1 to 3, wherein the component a) is present in an amount between about 20 and about 30 wt.%, preferably between about 20 and about 25 wt.%, the weight percentage 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 and about 35 wt.%, the weight percentage 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 component c) is a cyclic ester, preferably caprolactone.

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

8. A method for coating a silicon substrate, wherein the method comprises: a) Providing silicon substrates, particularly silicon wafers; b) Deposition of the UV-VIS curable composition according to claims 1 to 7; c) Spread the composition in a rotating manner, particularly by spin coating; d) Evaporate the solvent from the composition at least partially, preferably completely; e) Apply a mask to the UV-VIS curable composition to create a photolithographic pattern; f) Remove at least completely any uncured UV-VIS curable composition; g) The composition is at least partially cured.

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

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

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