Triarylsulfonium-based photoinitiators for led curing of cationic, radical and hybrid cationic / radical formulations

Abstract

The invention relates to compounds of formula (I): # imgabs0 # (I), to a method for the production thereof and to the use thereof as photoinitiators, preferably as photoinitiators that can be activated under light radiation of 350-460 nm, notably for curing formulations containing monomers that can be polymerized by cationic, free-radical and hybrid cationic / free-radical polymerizations.

Description

[0001] The present invention relates to photoinitiators for curing (e.g., LED curing) of epoxy and hybrid formulations with low energy light sources.

[0002] The increasing use of UV-visible curing technology in fields such as high-speed printing, surface coating, and additive manufacturing places high demands on the parameters of the polymer networks formed in these processes. In particular, reactive photoinitiators are needed that are thermally and chemically stable and, after activation by light or UV radiation, can act as catalysts for various acid-catalyzed and / or free radical-initiated polymerization reactions.

[0003] There is a need for photoinitiators that can be effectively activated by low energy light sources such as LEDs without the need for additional sensitizers, but that show high thermal stability in the formulation prior to exposure.

[0004] In addition, the photoinitiators and their photoproducts need to impart minimal coloring to the finished product and show low volatility and low toxicity.

[0005] Current cationic photoinitiators commonly used in the industry are typically aromatic sulfonium or iodonium salts.

[0006] Commercially available sulfonium salt photoinitiators include SpeedCure 992 and SpeedCure 976 (purchased from Sartomer), Omnicat 550 or Omnicat BL550 (purchased from IGM Resins). These triaryl sulfonium salts do not show sufficient UV absorption at longer wavelengths (385 - 405 nm) associated with LED light sources.

[0007] In addition, triaryl sulfonium salts do not respond to common sensitizers used to enhance UV absorption at LED wavelengths, such as thioxanthone. Sensitizers for sulfonium salts are available (e.g., 9,10-dialkoxyanthracene, e.g., ANTHRACURE UVs -1 331 and ANTHRACURE UVs -1 101), but these have significant costs.

[0008] Commercially available diaryl iodonium salt photoinitiators (e.g., Speedcure 938 purchased from Sartomer) can be effectively sensitized with thioxanthone, but generally have lower thermal stability and show higher toxicity compared to the corresponding sulfonium salts.

[0009] In addition, iodonium salts are generally more difficult to prepare than sulfonium salts.

[0010] In addition, iodonium salt photoinitiators and their photoproducts generally impart undesirable coloring to the finished product.

[0011] Therefore, there is a need for photoinitiators that have a high curing rate, good UV absorption, low yellowing, and good thermal stability at 385 - 405 nm and can be produced from readily available chemical structural units.

[0012] According to the first object, the present invention relates to a compound of formula (I):

[0013] (I)

[0014] Wherein:

[0015] - n is 1 or 2,

[0016] - Y is an anion with a valence of y,

[0017] - When n is 2, X is selected from a single bond, S, and O,

[0018] When n is 1, X is R 11 ,

[0019] Ar is an optionally substituted aromatic ring selected from benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, and phenyl,

[0020] Provided that:

[0021] - When Ar is selected from benzofuranyl, dibenzofuranyl, benzothiophenyl, and dibenzothiophenyl, n is 1,

[0022] - When Ar is phenyl and n is 1, the -Ar-X group has the following formula:

[0023] ,

[0024] Wherein:

[0025] - R 12 and R 13 are connected to each other such that the -Ar-X group represents

[0026] Wherein:

[0027] - R 16 、R 17 、R 18 and R 19 are independently selected from H, halogen, (C1 - C6) straight-chain or branched-chain alkyl, (C1 - C6) straight-chain or branched-chain alkoxy, -O-(CH2) i -COOR 28 or -(CH2) i -CH-(COOR 28 )2 group, where i is 1 or 2, and R 28is H or a (C1-C4) straight-chain or branched alkyl group, and

[0028] -R 11 、R 14 、R 15 are independently H, halogen, a (C1-C6) straight-chain or branched alkyl group, a (C1-C6) straight-chain or branched alkoxy group, and -S-Ph-C(=O)-Ph,

[0029] - or R 12 and R 13 are not connected to each other, and

[0030] R 11 、R 12 、R 13 、R 14 and R 15 are independently selected from H, halogen, a (C1-C6) straight-chain or branched alkyl group, a (C1-C6) straight-chain or branched alkoxy group, pyrrolidin-1-yl, -L-Ph 1 group, where L is a single bond, CH2 or O, and Ph 1 is a phenyl group optionally substituted with one or more substituents selected from halogen, a (C1-C6) straight-chain or branched alkyl group, and a (C1-C6) straight-chain or branched alkoxy group,

[0031] provided that at least one of the groups R 11 、R 12 and R 13 is selected from halogen, a (C1-C6) straight-chain or branched alkoxy group, pyrrolidin-1-yl, -L-Ph 1 group, where L is a single bond, CH2 or O, and Ph 1 is a phenyl group optionally substituted with one or more substituents selected from halogen, a (C1-C6) straight-chain or branched alkyl group, and a (C1-C6) straight-chain or branched alkoxy group,

[0032] - When Ar is a phenyl group and n is 2, the -Ar-X-Ar- group has the following formula:

[0033] or

[0034] where R 20 、R 21 、R 22 、R 23 、R 24 、R 25 、R 26 and R 27 are independently selected from H, a (C1-C6) straight-chain or branched alkyl group, a (C1-C6) straight-chain or branched alkoxy group, and -O-(CH2) j -COOR29 or -(CH2) j -CH-(COOR 29 )2 group, where j is 1 or 2, and R 29 is H or a (C1-C4) straight-chain or branched alkyl group,

[0035] -R 1 and R 6 are independently selected from H, halogen, a (C1-C6) straight-chain or branched alkyl group, a (C1-C6) straight-chain or branched alkoxy group, and -O-(CH2) k -COOR 30 or -(CH2) k -CH-(COOR 30 )2 group, where k is 1 or 2 and R 30 is H or a (C1-C4) straight-chain or branched alkyl group,

[0036] -Ph 2 is a phenyl group optionally substituted with one or more substituents selected from halogen, a (C1-C6) straight-chain or branched alkyl group, and a (C1-C6) straight-chain or branched alkoxy group,

[0037] -R 2 , R 4 , R 5 , R 7 , R 8 , R 9 and R 10 are independently selected from H, halogen, a (C1-C6) straight-chain or branched alkyl group, a (C1-C6) straight-chain or branched alkoxy group, and -O-(CH2) m -COOR 32 or -(CH2) m -CH-(COOR 32 )2 group, where m is 1 or 2, and R 32 is H or a (C1-C4) straight-chain or branched alkyl group.

[0038] The compound of formula (I) is an aromatic sulfonium salt photoinitiator, which is advantageously active under light irradiation at 350 - 460 nm, and is thus particularly suitable for the UV curing of cationic, free radical, and hybrid cationic / free radical formulations.

[0039] When cured with a light source of 350 to 460 nm, the compound having formula (I) advantageously exhibits a high curing rate, especially in pure cationic (e.g., epoxy or oxetane), free radical (e.g., (meth)acrylic acid or (meth)acrylate), and hybrid (e.g., epoxy / acrylic) formulations.

[0040] In the hybrid formulation, high conversions of both types of monomers are achieved without phase separation. This results in high strength and reduced shrinkage.

[0041] Compounds of formula (I) advantageously exhibit acceptable yellowing and / or photobleaching properties. The low yellowing properties can be measured by the color index 'b' value on the cured film. These low yellowing properties are important for applications in printing inks and additive manufacturing.

[0042] Formulations containing the monomer and the compound of formula (I) advantageously exhibit high thermal stability. This is important for the long shelf life of the active formulation (to avoid premature polymerization in the dark).

[0043] When applicable, the preferred embodiments below can be considered individually or in combination with each other, and when applicable, can be applied to formula (I) and any one of the formulas described below, in particular any one of the following formulas:

[0044] - The (C1-C6) straight or branched alkyl is (C1-C3) straight or branched alkyl, preferably methyl (Me), ethyl (Et), isopropyl (iPr) or n-propyl (nPr),

[0045] - The (C1-C6) straight or branched alkoxy is (C1-C3) straight or branched alkoxy, preferably -OMe, OEt, OiPr, -OnPr,

[0046] - The halogen is Cl or F,

[0047] - When n is 2, X is selected from a single bond and O,

[0048] - When n is 2, R 12 and R 13 One of them is selected from phenoxy and phenyl, wherein the phenoxy and phenyl are optionally substituted with one or more substituents selected from halogen, (C1-C6) straight or branched alkyl and (C1-C6) straight or branched alkoxy,

[0049] - R 1 、R 2 、R 4 and R 5 represent H,

[0050] - When R 8 represents (C1-C6) straight or branched alkyl, R 6 、R 7 、R 9 and R 10 represent H,

[0051] - R 1 、R 2 、R4 and R 5 and R 6 and R 7 and R 9 and R 10 represent H and R 8 represents a (C1-C6) straight-chain or branched-chain alkyl group, preferably a (C1-C3) straight-chain or branched-chain alkyl group, and most preferably a methyl group.

[0052] - When n is 1, X is H or a (C1-C6) straight-chain or branched-chain alkoxy group, preferably X is H or a (C1-C3) straight-chain or branched-chain alkoxy group, and most preferably X is H or OMe.

[0053] - R 12 and R 13 are connected to each other such that the group represents

[0054] - R 11 and R 14 and R 15 are independently H, halogen, a (C1-C6) straight-chain or branched-chain alkyl group, a (C1-C6) straight-chain or branched-chain alkoxy group, and -S-Ph-C(=O)-Ph. When R 11 is -S-Ph-C(=O)-Ph, R 1 and R 2 and R 4 and R 5 and R 6 and R 7 and R 8 and R 9 and R 10 and R 12 and R 13 and R 14 and R 15 are independently selected from H and a (C1-C6) straight-chain or branched-chain alkyl group.

[0055] --S-Ph-C(=O)-Ph is preferably

[0056] - R 20 and R 21 and R 22 and R 23 and R 24 and R 25 and R 26 and R 27 are independently selected from H, a (C1-C3) straight-chain or branched-chain alkyl group, and a (C1-C3) straight-chain or branched-chain alkoxy group.

[0057] - R 8 and / or R 13 is not methyl.

[0058] -Ph 2 represents unsubstituted phenyl,

[0059] -R 6 、R 7 、R 9 and R 10 represents H,

[0060] -R 8 represents H, halogen, (C1-C6) linear or branched alkyl, and (C1-C6) linear or branched alkoxy, and is preferably (C1-C6) linear or branched alkyl, most preferably methyl, and / or

[0061] -When L is a single bond, then Ph 1 is phenyl substituted by at least one (C1-C6) linear or branched alkoxy.

[0062] In any of the formulas described in this application, the anion Y y- is preferably selected from halides (F - , Cl - , Br - , I - ), HSO4 - ,SO4 2- , ClO4 - , BF4 - , PF6 - , AsF6 - , SbF6 - , SbF5(OH) - , SbF4(OH)2 - , BPh4 - , B(C6F5)4 - , Al[OC(CF3)3]4 - , CH3COO - , CH3SO3 - , CH3C6H4SO3 - , CF3COO - , CF3SO3 - , N(CF3SO3)2 - , or B[C6H3(CF3)2]4 - and is most preferably selected from PF6 - 、SbF6 - and B(C6F5)4 - .

[0063] In a first alternative, in formula (I), n is 1 and X is R11 and R 12 and R 13 are connected to each other such that the group represents and the compound matches formula (III):

[0064] (III)

[0065] wherein R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 8 、R 9 、R 10 、R 11 、R 14 、R 15 、R 16 、R 17 、R 18 、R 19 、Ph 2 、Y and y are as defined above.

[0066] When applicable, the preferred embodiments of formula (III) below can be considered individually or in combination with each other:

[0067] - Ph 2 represents an unsubstituted phenyl group,

[0068] - R 1 、R 2 、R 4 and R 5 represent H,

[0069] - R 6 、R 7 、R 9 and R 10 represent H,

[0070] - R 8 represents a group selected from H, halogen, (C1-C6) straight or branched chain alkyl, and (C1-C6) straight or branched chain alkoxy, and is preferably (C1-C6) straight or branched chain alkyl, most preferably methyl,

[0071] - R 11 、R 14 and R 15 represent H,

[0072] - R 16 、R 17 、R 18 and R 19at least one of the groups, most preferably R 16 、R 17 、R 18 and R 19 one or two of the groups are selected from halogen, (C1-C6) straight-chain or branched-chain alkyl, (C1-C6) straight-chain or branched-chain alkoxy, -O-(CH2) i -COOR 28 or -(CH2) i -CH-(COOR 28 )2 group, where i is 1 or 2, and R 28 is H or (C1-C4) straight-chain or branched-chain alkyl, and preferably (C1-C6) straight-chain or branched-chain alkyl, and R 16 、R 17 、R 18 and R 19 the remaining other groups are H;

[0073] Notably, R 16 and R 18 are H, and at least one of R 17 and R 19 is selected from halogen, (C1-C6) straight-chain or branched-chain alkyl, (C1-C6) straight-chain or branched-chain alkoxy, -O-(CH2) i -COOR 28 or -(CH2) i -CH-(COOR 28 )2 group, where i is 1 or 2, and R 28 is H or (C1-C4) straight-chain or branched-chain alkyl, and preferably (C1-C6) straight-chain or branched-chain alkyl, and the remaining other group R 17 or R 19 is H, and / or

[0074] - When L is a single bond, then Ph 1 is a phenyl group substituted with at least one (C1-C6) straight-chain or branched-chain alkoxy group.

[0075] Preferred compounds are those having formula (2), (3), (4), (41), (42) or (43), most preferably formula (2) or (4):

[0076] (2),

[0077] (3),

[0078] (4),

[0079] (41),

[0080] (42),

[0081] (43),

[0082] wherein Y and y are as defined above.

[0083] In the second alternative of formula (I), n is 1 and X is R 11 and the -Ar-X group has the following formula:

[0084] ,

[0085] wherein R 12 and R 13 are not connected to each other, such that the compound has formula (VI), wherein:

[0086] (VI),

[0087] wherein R 1 , R 2 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , Ph 2 , Y and y are as defined above.

[0088] When applicable, the preferred embodiments of formula (VI) below can be considered individually or in combination with each other:

[0089] - Ph 2 represents an unsubstituted phenyl group,

[0090] - R 1 , R 2 , R 4 and R 5 represent H,

[0091] - R 6 , R 7 , R 9 and R 10 represent H,

[0092] - R 8is selected from H, halogen, (C1-C6) linear or branched alkyl, and (C1-C6) linear or branched alkoxy, and is preferably (C1-C6) linear or branched alkyl, most preferably methyl,

[0093] - R 13 is selected from halogen, (C1-C6) linear or branched alkoxy, pyrrolidin-1-yl, -L-Ph 1 group, where L is a single bond, CH2 or O, and Ph 1 is a phenyl optionally substituted with one or more substituents selected from halogen, (C1-C6) linear or branched alkyl, and (C1-C6) linear or branched alkoxy, R 13 is preferably selected from (C1-C6) linear or branched alkoxy (such as methoxy), pyrrolidin-1-yl, -L-Ph 1 group, where L is a single bond, CH2 or O, and Ph 1 is a phenyl optionally substituted with one or more substituents selected from halogen, (C1-C6) linear or branched alkyl, and (C1-C6) linear or branched alkoxy, preferably selected from (C1-C6) linear or branched alkyl and (C1-C6) linear or branched alkoxy, such as methoxy,

[0094] - R 11 and R 15 are independently selected from H and (C1-C6) linear or branched alkyl, (C1-C6) linear or branched alkoxy, preferably selected from H and methoxy,

[0095] - R 12 and R 14 is H,

[0096] - R 11 、R 14 and R 15 are H,

[0097] - R 12 and R 13 at least one of the groups is selected from halogen, (C1-C6) linear or branched alkoxy, pyrrolidin-1-yl, -L-Ph 1 group, where L is a single bond, CH2 or O, and Ph 1 is a phenyl optionally substituted with one or more substituents selected from halogen, (C1-C6) linear or branched alkyl, and (C1-C6) linear or branched alkoxy, preferably R 12 and R 13 at least one of the groups is selected from (C1-C6) linear or branched alkoxy and -L-Ph 1 group, and R 12 or R 13The remaining other groups therein are H

[0098] - R 12 and R 13 are independently selected from halogen, (C1-C6) straight-chain or branched alkoxy, pyrrolidin-1-yl, -L-Ph 1 group, where L is a single bond, CH2 or O, and Ph 1 is a phenyl optionally substituted with one or more substituents selected from halogen, (C1-C6) straight-chain or branched alkyl, and (C1-C6) straight-chain or branched alkoxy, preferably selected from (C1-C6) straight-chain or branched alkoxy, such as methoxy and -L-Ph 1 group, and / or

[0099] - Ph 1 is a phenyl optionally substituted with one or more substituents selected from (C1-C6) straight-chain or branched alkoxy, preferably methoxy, and / or

[0100] - When L is a single bond, then Ph 1 is a phenyl substituted with at least one (C1-C6) straight-chain or branched alkoxy.

[0101] Preferred compounds are those of formula (7), (9), (11), (18), (25) and (27), most preferably formula (25) or (27):

[0102] (7),

[0103] (9),

[0104] (11),

[0105] (18),

[0106] (25),

[0107] (27),

[0108] where Y and y are as defined above.

[0109] In one embodiment, in formula (VI), R 11 is -S-Ph-C(=O)-Ph, and the compound has formula (VIII):

[0110] (VIII),

[0111] where R 1 、R 2 、R4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 12 , R 13 , R 14 , R 15 , Ph 2 , Y and y are as defined above.

[0112] According to the third alternative of formula (I), Ar is phenyl and n is 2, and the compound matches formula (IX):

[0113] (IX),

[0114] wherein:

[0115] -R 1 , R 2 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , Ph 2 , Y and y are as defined above,

[0116] --The -Ar-X-Ar- group has the following formula:

[0117] or ,

[0118] where R 20 , R 21 , R 22 , R 23 , R 24 , R 25 , R 26 and R 27 are as defined above.

[0119] In one embodiment, in formula (IX), the -Ar-X-Ar- group has the following formula:

[0120] ,

[0121] such that the compound matches formula (X):

[0122] (X),

[0123] wherein:

[0124] -R 1 , R 2 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 20 , R 21 , R 22 , R 23 , Ph 2 , X, Y and y are as defined above.

[0125] Where applicable, the preferred embodiments of formula (X) below can be considered individually or in combination with one another:

[0126] -Ph 2 represents an unsubstituted phenyl group,

[0127] -R 1 , R 2 , R 4 and R 5 Indicates H,

[0128] -R 6 , R 7 , R 9 and R 10 Indicates H,

[0129] -R 8 represents a group selected from H, halogen, (C1-C6) straight chain or branched alkyl and (C1-C6) straight chain or branched alkoxy, and is preferably (C1-C6) straight chain or branched alkyl, most preferably methyl,

[0130] -R 20 , R 22 and R 23 represents H, and R 21 Selected from H, (C1-C6) straight chain or branched alkyl, (C1-C6) straight chain or branched alkoxy and -O-(CH2) j -COOR 29 or -(CH2) j -CH-(COOR 29 )2 group, wherein j is 1 or 2, and R 29 is H or (C1-C4) straight or branched chain alkyl, preferably R 21 Selected from H, (C1-C6) straight chain or branched alkyl, most preferably R 21 It is methyl.

[0131] Preferred compounds have formula (29):

[0132] (29),

[0133] wherein Y and y are as defined above.

[0134] In a fourth alternative, in formula (I), n is 1 and Ar is selected from benzofuranyl, dibenzofuranyl, benzothiophenyl and dibenzothiophenyl, such that the compound matches formula (XIV):

[0135] (XIV),

[0136] wherein:

[0137] -R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 6 、R 8 、R 9 、R 10 、R 11 、Ph 2 、Y and y are as defined above, and

[0138] -Ar is selected from benzofuranyl, dibenzofuranyl, benzothiophenyl and dibenzothiophenyl.

[0139] When applicable, the preferred embodiments of formula (XIV) below can be considered individually or in combination with each other:

[0140] --Ar-R 11 is selected from:

[0141] ,

[0142] ,

[0143] , ,

[0144] and ,

[0145] - Ph 2 represents an unsubstituted phenyl group,

[0146] - R 1 、R 2 、R 4 and R 5 represent H,

[0147] - R 6 、R7 , R 9 and R 10 represent H, and / or

[0148] -R 8 represents a group selected from H, halogen, (C1-C6) linear or branched alkyl, and (C1-C6) linear or branched alkoxy, and is preferably (C1-C6) linear or branched alkyl, most preferably methyl.

[0149] Preferred compounds are those of formulae (10), (19), (20) and (21):

[0150] (19),

[0151] (20),

[0152] (10),

[0153] (21),

[0154] wherein Y and y are as defined above.

[0155] According to a second object, the present invention relates to a process for preparing a compound of formula (I) as defined above, comprising the steps of:

[0156] b) reacting a compound of formula (XXI):

[0157] (XXI),

[0158] wherein R 1 , R 2 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 and Ph 2 are as defined above,

[0159] - with a compound of formula (XXII):

[0160] H-Ar-R 11 (XXII)

[0161] wherein R 11 is as defined above, and

[0162] Ar is an optionally substituted aromatic ring selected from benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl and phenyl of the following formula:

[0163]

[0164] wherein R 11 、R 12 、R 13 、R 14 and R 15 are as defined above,

[0165] to form a compound of formula (I) wherein n is 1 and X is R 11 of formula (I),

[0166] - or react with a compound of formula (XXV):

[0167] (XXV)

[0168] wherein

[0169] -R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 8 、R 9 、R 10 and Ph 2 are as defined above,

[0170] -- the Ar-X-Ar-H group has the formula:

[0171] or

[0172] wherein:

[0173] -R 20 、R 21 、R 22 、R 23 、R 24 、R 25 、R 26 and R 27 are as defined above,

[0174] - X is selected from a single bond, S and O,

[0175] to form a compound of formula (I) wherein n is 2 and X is selected from a single bond, S and O,

[0176] in the presence of an activator,

[0177] whereby a compound of formula (I) is obtained,

[0178] c) when it is desired that Y y- is different from the Y y-When the compound of formula (I) is used, it is subjected to an ion exchange reaction with a salt containing Y' y- as the anion or an acid having Y' y- as the base to obtain the compound of formula (I) as follows: wherein Y' y- has the same definition as Y defined above y- , but is different from the Y obtained in step b) y- .

[0179] In step b), the activator is typically selected from trifluoromethanesulfonic anhydride ((CF3SO2)2O, Tf2O), methanesulfonic anhydride ((CH3SO2)2O), trifluoroacetic anhydride ((CF3CO)2O), acetic anhydride ((CH3CO)2O), aluminum chloride (AlCl3) and phosphorus pentoxide (P2O5). The activator is optionally used in combination with a strong Brønsted ) acid such as trifluoromethanesulfonic acid, methanesulfonic acid, trifluoroacetic acid or sulfuric acid. Preferably, the activator is trifluoromethanesulfonic anhydride ((CF3SO2)2O, Tf2O).

[0180] Typically, step b) is carried out at a temperature of -60 °C to -50 °C.

[0181] The method may include, after step b), a step of purifying the compound of formula (I) obtained at the end of step b), for example, by column chromatography.

[0182] When step b) produces a compound of formula (I) in which Y y- is the desired anion, the method does not include step c). For example, when the activator is trifluoromethanesulfonic anhydride ((CF3SO2)2O, Tf2O), a compound of formula (I) is obtained in which the anion Y y- is CF3SO3 - . If CF3SO3 - is the desired anion Y y- in formula (I), then step c) is not carried out.

[0183] When step b) produces a compound of formula (I) in which Y y- is not the desired anion, the method includes the ion exchange step c). In the above example, if the desired anion Y y- in formula (I) is different from CF3SO3 - , for example, if PF6 - is the desired Y' y- , then step c) is usually carried out with sodium hexafluorophosphate or hexafluorophosphoric acid.

[0184] In step c), the salt containing Y y- as the anion can be an alkali metal salt, such as a sodium salt or a potassium salt.

[0185] Step c) is generally carried out in the presence of an organic solvent. Suitable organic solvents include chloroform, dichloromethane and acetic acid.

[0186] Scheme 1 below shows a method for preparing a compound of formula (I), where n is 1.

[0187]

[0188] Scheme 1

[0189] When preparing a compound of formula (I) where n is 2, the method may include step b0) of preparing a compound of formula (XXV), which comprises reacting a compound of formula (XXI):

[0190] (XXI),

[0191] where R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 8 、R 9 、R 10 and Ph 2 are as defined above,

[0192] with a compound of formula (XXIVa) or (XXIVb):

[0193] or

[0194] where:

[0195] -R 20 、R 21 、R 22 、R 23 、R 24 、R 25 、R 26 and R 27 are as defined above,

[0196] -X is selected from a single bond, S and O

[0197] in the presence of an activator.

[0198] Scheme 2 below illustrates a method for preparing a compound of formula (I), where n is 2.

[0199]

[0200] Scheme 2

[0201] Scheme 3 below illustrates a method for preparing a compound of formula (I), where n is 2 and -Ar-X-Ar- is

[0202]

[0203] Scheme 4 below illustrates a method for preparing a compound of formula (I), where n is 2 and -Ar-X-Ar- is

[0204]

[0205] Scheme 4

[0206] The method may include, before step b), step a) of preparing a compound of formula (XXI) by oxidizing a compound of formula (XX):

[0207] (XX),

[0208] wherein R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 8 、R 9 、R 10 and Ph 2 are as defined above. The oxidation is the selective oxidation of the compound of formula (XX) to the corresponding sulfoxide.

[0209] Step a) is generally carried out in the presence of an oxidizing agent, which is generally selected from peroxides (such as m-chloroperbenzoic acid (m-CPBA), peracetic acid, performic acid and hydrogen peroxide), transition metal salts (such as ammonium cerium nitrate) and higher valent halogen compounds (such as sodium hypochlorite), and the oxidizing agent is preferably m-CPBA.

[0210] Step a) can be carried out in the absence or presence of an organic solvent. Suitable organic solvents include chloroform, dichloromethane, acetonitrile or acetic acid.

[0211] Scheme 5 below illustrates a method for preparing a compound of formula (XXI).

[0212]

[0213] The method may include, after step a), a step of purifying the compound of formula (XXI) by, for example, column chromatography.

[0214] According to a third object, the present invention relates to the use of the above compounds as photoinitiators, preferably as photoinitiators activatable under light irradiation at 350 - 460 nm. The photoinitiators of the present invention have potential applications in UV-curable printing inks, electronic devices, and additive manufacturing (3D printing).

[0215] The present invention also relates to the use of the compounds as photoinitiators for the UV curing of formulations comprising monomers which can be polymerized by cationic, radical, and hybrid cationic / radical polymerization. The present invention also relates to a method for curing a formulation comprising monomers which can be polymerized by cationic polymerization, radical polymerization, and hybrid cationic / radical polymerization, the method comprising adding a compound of formula (I) as defined above as a photoinitiator to the formulation and UV curing.

[0216] Epoxy or oxetane formulations are examples of cationic formulations. (Meth)acrylic acid or (meth)acrylate formulations are examples of radical formulations. Hybrid formulations contain monomers capable of being polymerized by cationic polymerization and monomers capable of being polymerized by radical polymerization. Epoxy / (meth)acrylic formulations are examples of hybrid cationic / radical formulations.

[0217] The compounds having formula (I) advantageously exhibit high curing rates, low yellowing and / or photo-bleaching properties, and high thermal stability in formulations. The yellowing property can be measured by the color index 'b' value on the cured film.

[0218] According to a fourth object, the present invention relates to a photoinitiator composition comprising a mixture of compounds of formula (I).

[0219] According to a fifth object, the present invention relates to a curable composition comprising:

[0220] - a compound of formula (I) as defined above or a photoinitiator composition as defined above; and

[0221] - a cationically polymerizable compound.

[0222] Based on the total weight of the curable composition, the curable composition may comprise from 0.05 wt% to 10 wt%, particularly from 0.1 wt% to 5 wt%, more particularly from 0.5 wt% to 2 wt% of the compound of formula (I). If the curable composition comprises a mixture of compounds of formula (I), the above weight percentages can be calculated using the weight of the mixture of compounds of formula (I).

[0223] The term "cationically polymerizable compound" refers to a compound containing a polymerizable functional group that polymerizes by a cationic mechanism, such as a heterocyclic group or a carbon-carbon double bond substituted with an electron-donating group. In the cationic polymerization mechanism, a cationic initiator forms a Bronsted acid or Lewis acid species that binds to the cationically polymerizable compound, which then becomes reactive and causes chain growth by reacting with another cationically polymerizable compound.

[0224] The cationically polymerizable compound may be selected from epoxy-functionalized compounds, oxetanes, oxolanes, cyclic acetals, cyclic lactones, thiiranes, thietanes, spiro orthoesters, ethylenically unsaturated compounds other than (meth)acrylates, derivatives thereof, and mixtures thereof, and is preferably selected from epoxy-functionalized compounds, oxetanes, polyols, and mixtures thereof.

[0225] Based on the total weight of the curable composition, the curable composition may include 5% to 99% by weight, preferably 10% to 98% by weight, more preferably 20% to 97% by weight of one or more cationically polymerizable compounds. If the composition contains a mixture of cationically polymerizable compounds, the above weight percentages may be calculated using the weight of the mixture of cationically polymerizable compounds.

[0226] In a preferred embodiment, the cationically polymerizable compound contains at least one compound selected from epoxides, oxetanes, oxolanes, cyclic acetals, cyclic lactones, thiiranes, thietanes, spiro orthoesters, vinyl ethers, and mixtures thereof.

[0227] In the most preferred embodiment, the cationically polymerizable compound contains an alicyclic epoxide and optionally an oxetane.

[0228] Epoxide

[0229] Epoxide is also referred to as epoxide or epoxy-functional compound in the present invention.

[0230] The epoxy-functional compound may be a monomer and / or an oligomer.

[0231] Exemplary epoxy-functional compounds suitable for use include monoxides, dioxides, and polyoxides (compounds containing three or more epoxy groups per molecule). Alicyclic polyglycidyl compounds and cycloaliphatic polyoxides are two classes of suitable epoxy-functional compounds. Such compounds contain two or more epoxy groups per molecule and may have a cycloaliphatic ring structure with epoxy groups as side groups (side-attached to the cycloaliphatic ring), or may have a structure in which the epoxy groups are part of the cycloaliphatic ring structure.

[0232] The epoxy-functional compound may comprise, consist essentially of, or consist of at least one epoxy ether. As used herein, the term "epoxy ether" refers to a compound containing at least two epoxy groups and at least one ether bond (the ether bond being different from the cyclic ether bond in the epoxy group). In particular, the epoxy ether may contain at least two epoxy groups and at least two ether bonds (the ether bond being different from the cyclic ether bond in the epoxy group).

[0233] The epoxy-functional compound may comprise, consist essentially of, or consist of at least one glycidyl ether. As used herein, the term "glycidyl ether" refers to a compound containing at least two glycidyl ether groups. As used herein, the term "glycidyl ether group" means a group of the following formula (A): (A).

[0234] In one embodiment, the epoxy compound may comprise, consist essentially of, or consist of at least one compound having two glycidyl ether groups, also referred to as a diglycidyl ether. In another embodiment, the epoxy may comprise, consist essentially of, or consist of at least one compound having three glycidyl ether groups.

[0235] The epoxy may comprise, consist essentially of, or consist of at least one compound selected from aromatic epoxies, aliphatic epoxies, and mixtures thereof.

[0236] The epoxy may comprise, consist essentially of, or consist of at least one aromatic epoxy. As used herein, the term "aromatic epoxy" refers to a compound containing at least two epoxy groups connected to each other through an aromatic linking group.

[0237] As used herein, the term "aromatic linking group" refers to a linking group containing at least one aromatic ring, preferably at least two aromatic rings, more preferably 2 or 3 aromatic rings. An araliphatic linking group, i.e., a linking group containing both an aromatic moiety and a non-aromatic moiety, is encompassed by the term aromatic linking group.

[0238] The aromatic epoxy may be an aromatic glycidyl ether. As used herein, the term "aromatic glycidyl ether" refers to a compound containing at least two glycidyl ether groups connected to each other through an aromatic linking group. Such a compound may be represented by the following formula (B):

[0239] (B)

[0240] where Ar is an aromatic linking group;

[0241] a is at least 2, preferably 2 to 10, more preferably 2 to 6.

[0242] The aromatic glycidyl ether can be a bisphenol-based glycidyl ether. As used herein, the term "bisphenol-based glycidyl ether" refers to a compound containing at least two glycidyl ether groups, which are connected to each other through an aromatic linking group containing a moiety derived from bisphenol. Such a compound can be represented by the above formula (B), where a is 2 and Ar is represented by the following formula (C):

[0243] (C)

[0244] where L is a linking group;

[0245] R 1 and R 2 are independently selected from alkyl, cycloalkyl, aryl, and halogen atoms;

[0246] b and c are independently 0 to 4.

[0247] In particular, L can be a linking group selected from a bond, -CR3R4 - 、-C(=O)-、-SO-、-SO2-、-C(=CCl2)-, and -CR5R6-Ph-CR7R 8- ; where

[0248] R3 and R4 are independently selected from H, alkyl, cycloalkyl, aryl, haloalkyl, and perfluoroalkyl, or R3 and R4 together with the carbon atom to which they are attached can form a ring; R5, R6, R7, and R8 are independently selected from H, alkyl, cycloalkyl, aryl, haloalkyl, and perfluoroalkyl;

[0249] Ph is a phenylene group optionally substituted with one or more groups selected from alkyl, cycloalkyl, aryl, and halogen atoms.

[0250] More particularly, Ar can be the residue of a bisphenol without an OH group. The compound according to formula (C) (where Ar is the residue of a bisphenol without an OH group) can be referred to as a bisphenol-based epoxy ether, preferably a bisphenol-based glycidyl ether. Examples of suitable bisphenols are bisphenol A, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol C2, bisphenol F, bisphenol G, bisphenol M, bisphenol S, bisphenol P, bisphenol PH, bisphenol TMC, bisphenol-Z, dinitrobisphenol A, tetrabromobisphenol A, and combinations thereof.

[0251] The epoxy-functional compound can comprise, consist of, or consist essentially of at least one aliphatic epoxy. As used herein, the term "aliphatic epoxy" refers to a compound containing at least two epoxy groups connected to each other through an aliphatic linking group.

[0252] As used herein, the term "aliphatic linking group" means a linking group that does not contain any aromatic rings. It can be a straight-chain or branched-chain, cyclic or acyclic, saturated or unsaturated hydrocarbon linking group. It can be substituted by one or more groups, such as selected from hydroxyl, halogen (Br, Cl, I, F), carbonyl, amine, carboxylic acid, -C(=O)-OR', -C(=O)-O-C(=O)-R', where each R' is independently a C1-C6 alkyl group. It can be interrupted by one or more bonds selected from ether (-O-), ester (-C(=O)-O- or -O-C(=O)-), amide (-C(=O)-NH- or -NH-C(=O)-), carbamate (-NH-C(=O)-O- or -O-C(=O)-NH-), urea (-NH-C(=O)-NH-), carbonate (-O-C(=O)-O-) and mixtures thereof.

[0253] The at least one aliphatic epoxy can be selected from aliphatic glycidyl ethers, epoxidized vegetable oils, and combinations thereof.

[0254] The aliphatic epoxy can be an aliphatic glycidyl ether. As used herein, the term "aliphatic glycidyl ether" refers to a compound containing at least two glycidyl ether groups linked to each other through an aliphatic linking group. Such a compound can be represented by the following formula (D):

[0255] (D)

[0256] where Al is an aliphatic linking group;

[0257] d is at least 2, preferably 2 to 10, more preferably 2 to 6.

[0258] In particular, Al can be an alkylene group optionally interrupted by one or more ether or ester bonds or Al can correspond to a partially or fully hydrogenated derivative of the linking group of formula (C).

[0259] More particularly, Al can be the residue of a polyol P OH without an OH group. Suitable polyols P OHExamples include ethylene glycol, 1,2- or 1,3-propanediol, 1,2-, 1,3- or 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 2-methyl-1,3-propanediol, 2,2-diethyl-1,3-pentanediol, 3-dimethyl-1,5-pentanediol, 3,3-dimethyl-1,5-pentanediol, neopentyl glycol, 2,4-diethyl-1,5-pentanediol, cyclohexanediol, cyclohexane-1,4-dimethanol, norbornene dimethanol, norbornane dimethanol, tricyclodecane diol, tricyclodecane dimethanol, hydrogenated bisphenol A / B / F / S, trimethylolmethane, trimethylolethane, trimethylolpropane, di(trimethylolpropane), triethylolpropane, pentaerythritol, di(pentaerythritol), glycerol, diglycerol / triglycerol / tetraglycerol, polyglycerol, di-, tri- or tetraethylene glycol, di-, tri- or tetrapropylene glycol, di-, tri- or tetrabutylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly(ethylene-co-propylene) glycol, sugar alcohols (i.e., erythritol, threitol, arabitol, xylitol, ribitol, mannitol, sorbitol, galactitol, fucitol, iditol), dianhydrosugar alcohols (i.e., isosorbide, isomannide, isoiditol), hydroxylated vegetable oils, tris(2-hydroxyethyl) isocyanurate, polybutadiene polyol, polyester polyol, polyether polyol, polysiloxane polyol, polycarbonate polyol, and alkoxylated (e.g., ethoxylated and / or propoxylated) derivatives thereof, and derivatives obtained by ring-opening polymerization of ε-caprolactone initiated by one of the foregoing polyols.

[0260] The epoxide may be an alkoxylated alicyclic epoxide conforming to the following formula (E):

[0261] (E)

[0262] where each R 1 and R 2 are independently selected from H and Me;

[0263] L is the residue of a polyol, preferably (HO-CH2-)3C-CH2)2O;

[0264] each a is independently 2 to 4, preferably 2 or 4;

[0265] each b is independently 0 to 20, provided that at least one b is not 0;

[0266] c is at least 3, preferably 3 to 10, especially 3 to 8, more especially 4 to 6.

[0267] The aliphatic epoxide may be an epoxidized vegetable oil.

[0268] As used herein, the term "epoxidized vegetable oil" refers to an unsaturated vegetable oil in which at least some of the carbon-carbon double bonds have been converted to epoxides. Unsaturated vegetable oils typically contain one or more unsaturated diglycerides and / or triglycerides. The unsaturated diglycerides and triglycerides can correspond to diesters and triesters of glycerol with one or more fatty acids, where at least some of the fatty acids are unsaturated fatty acids. Fatty acids can be defined as monocarboxylic acids containing from 4 to 32 carbon atoms, particularly from 8 to 30 carbon atoms, more particularly from 10 to 28 carbon atoms. Unsaturated fatty acids correspond to fatty acids containing one or more carbon-carbon double bonds. Examples of unsaturated fatty acids are myristoleic acid, palmitoleic acid, petroselinic acid, oleic acid, ricinoleic acid, elaidic acid, isolenic acid, linoleic acid, elaidolinoleic acid, α-linolenic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, docosahexaenoic acid, and combinations thereof. Unsaturated vegetable oils can be extracted from plants or trees, such as from the seeds, fruits, flowers, bark, wood, stems or leaves of plants or trees. Examples of suitable epoxidized vegetable oils include epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, epoxidized corn oil, epoxidized cottonseed oil, epoxidized perilla oil, epoxidized safflower oil, epoxidized palm oil, epoxidized coconut oil, epoxidized rapeseed oil, epoxidized jatropha oil, epoxidized rubber seed oil, epoxidized tung oil, epoxidized tall oil, and combinations thereof.

[0269] Also suitable are straight-chain or branched epoxidized polyenes, such as epoxidized polybutadiene and its copolymers, polyisoprene and its copolymers.

[0270] Examples of compounds in which the epoxy group forms part of an alicyclic ring system include bis(2,3-epoxycyclopentyl) ether; 2,3-epoxycyclopentyl glycidyl ether, 1,2-bis(2,3-epoxycyclopentyloxy)ethane; bis(4-hydroxycyclohexyl)methane diglycidyl ether, 2,2-bis(4-hydroxycyclohexyl)propane diglycidyl ether; 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate; 3,4-epoxy-6-methyl-cyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate; di(3,4-epoxycyclohexylmethyl) adipate; di(3,4-epoxy-6-methylcyclohexylmethyl) adipate; ethylenebis(3,4-epoxycyclohexane-carboxylate, ethylene glycol bis(3,4-epoxycyclohexylmethyl) ether, vinylcyclohexene dioxide, dicyclopentadiene diepoxide and 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy-)cyclohexane-1,3-dioxane.

[0271] Suitable exemplary monoxides include: glycidyl (meth)acrylate and (3,4-epoxycyclohexyl)methyl (meth)acrylate and other monoepoxide compounds containing an epoxy group and a (meth)acrylate group.

[0272] Suitable exemplary diepoxides include diglycidyl ethers of diols and diglycidyl esters of diacids, such as: ethylene glycol diglycidyl ether, oligo- and polyethylene glycol diglycidyl ethers, propylene glycol diglycidyl ether, oligo- and polypropylene glycol diglycidyl ethers, butanediol diglycidyl ether, alkoxylated (e.g., ethoxylated, propoxylated) butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, alkoxylated (e.g., ethoxylated, propoxylated) neopentyl glycol diglycidyl ether, hexanediol diglycidyl ether, alkoxylated (e.g., ethoxylated, propoxylated) hexanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, alkoxylated (e.g., ethoxylated, propoxylated) cyclohexanedimethanol diglycidyl ether, hydrogenated or non-hydrogenated bisphenol A diglycidyl ether (BADGE), hydrogenated or non-hydrogenated bisphenol F diglycidyl ether (BFDGE), alkoxylated (e.g., ethoxylated, propoxylated) diglycidyl ethers of bisphenols (e.g., bisphenol A or bisphenol F or their hydrogenated derivatives), diglycidyl ethers of o-, m- or p-phthalic acid, diglycidyl ether of tetrahydrophthalic acid and diglycidyl ether of hexahydrophthalic acid.

[0273] Suitable exemplary polyepoxides include glycidyl ethers of compounds having three or more hydroxyl groups, such as hexane-2,4,6-triol; glycerol; 1,1,1-trimethylolpropane; ditrimethylolpropane; pentaerythritol; sorbitol; and their alkoxylated (e.g., ethoxylated, propoxylated) derivatives, novolac resins, etc.

[0274] In certain embodiments, the curable composition may comprise one or more polymerizable heterocyclic moiety-containing compounds that contain one or more polymerizable sites that are ethylenically unsaturated in addition to one or more epoxy groups, such as may be provided by (meth)acrylate groups, (meth)acrylamide groups, vinyl groups, allyl groups, etc. Glycidyl methacrylate and glycidyl acrylate are specific examples of such polymerizable heterocyclic moiety-containing compounds. These compounds are considered to be epoxy groups when calculating the relative amounts of oxetane and epoxy groups in the cationically curable compounds in the composition. Examples of suitable epoxy (meth)acrylates include the reaction products of acrylic acid or methacrylic acid or mixtures thereof with glycidyl ethers or esters.

[0275] Oxetane compounds

[0276] Oxetane compounds are also referred to as oxetanes or oxetane-functional compounds in the present invention.

[0277] Oxetanes can be monomers and / or oligomers.

[0278] Suitable exemplary oxetanes include oxetane itself and its substituted derivatives, provided that the substituents do not interfere with the desired reactions / polymerizations / curing of the oxetane. Substituents can be, for example, alkyl, hydroxyalkyl, halogen, haloalkyl, aryl, aralkyl, etc. The oxetane can be a mono-oxetane (a compound containing a single oxetane ring), a di-oxetane (a compound containing two oxetane rings), a tri-oxetane (a compound containing three oxetane rings), or an oxetane compound containing four or more oxetane rings. Examples of suitable oxetanes include, but are not limited to, oxetane, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 3-ethyl-3-phenoxymethyloxetane, 3-ethyl-3-{[(3-ethyloxetanyl)methoxy]methyl}oxetane, 3,3-bis(chloromethyl)oxetane, 3-ethyl-3-[(benzyloxy)methyl]oxetane, 4,4'-bis(3-ethyl-3-oxetanylmethoxymethyl)biphenyl, 3,3-bis(iodomethyl)oxetane, 3,3-bis(methoxymethyl)oxetane, 3,3-bis(phenoxymethyl)oxetane, 3-methyl-3-chloromethyloxetane, 3,3-bis(acetoxymethyl)oxetane, 3,3-bis(fluoromethyl)oxetane, 3,3-bis(bromomethyl)oxetane, 3,3-dimethyloxetane, 3-ethyl-3-[[(2-ethylhexyl)oxy]methyl]oxetane, bis(3-ethyloxetanyl)methoxysilane, trimethylolpropane tris(3-ethyl-3-oxetanylmethyl)ether, and the like, and their compositions.

[0279] Examples of compounds that can be used and that have two or more oxetane rings in the compound include: 3,7-bis(3-oxetanyl)-5-oxanonane, 3,3′-(1,3-(2-methylene)propylidenedioxybis(methylene))bis-(3-ethyloxetane), 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane, 1,3-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, ethylene glycol bis(3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyl bis(3-ethyl-3-oxetanylmethyl) ether, triethylene glycol bis(3-ethyl-3-oxetanylmethyl) ether, tetraethylene glycol bis(3-ethyl-3-oxetanylmethyl) ether, tricyclodecane diyl dimethylene(3-ethyl-3-oxetanylmethyl) ether, trimethylolpropane tris(3-ethyl-3-oxetanylmethyl) ether, 1,4-bis(3-ethyl-3-oxetanylmethoxy)butane, 1,6-bis(3-ethyl-3-oxetanylmethoxy)hexane, pentaerythritol tris(3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tetra(3-ethyl-3-oxetanylmethyl) ether, polyethylene glycol bis(3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol hexa(3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol penta(3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol tetra(3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol hexa(3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol penta(3-ethyl-3-oxetanylmethyl) ether, bis-trimethylolpropane tetra(3-ethyl-3-oxetanylmethyl) ether, EO-modified bisphenol A bis(3-ethyl-3-oxetanylmethyl) ether, PO-modified bisphenol A bis(3-ethyl-3-oxetanylmethyl) ether, EO-modified hydrogenated bisphenol A bis(3-ethyl-3-oxetanylmethyl) ether, PO-modified hydrogenated bisphenol A bis(3-ethyl-3-oxetanylmethyl) ether, EO-modified bisphenol F(3-ethyl-3-oxetanylmethyl) ether, and the like and their combinations.

[0280] Additional examples of suitable oxetanes are described in the following patent documents, the disclosures of each of which are incorporated herein by reference in their entirety for all purposes: U.S. Patent Publication No. 2010 / 0222512 A1, U.S. Patent No. 3,835,003, U.S. Patent No. 5,750,590, U.S. Patent No. 5,674,922, U.S. Patent No. 5,981,616, U.S. Patent No. 6,469,108, U.S. Patent No. 6,015,914, and U.S. Patent No. 8377623. Suitable oxetanes are commercially available, such as oxetanes sold by Toagosei Corporation under the trade names OXT-221, OXT-121, OXT-101, OXT-212, OXT-211, CHOX, OX-SC, and PNOX-1009.

[0281] Also suitable are oxetanes that further comprise one or more ethylenically unsaturated polymerizable sites, such as may be provided by (meth)acrylate groups, (meth)acrylamide groups, vinyl groups, allyl groups, etc. 3-Ethyl-3-(methacryloyloxy)methyloxetane or (3-ethyloxetan-3-yl)methyl acrylate are specific examples of such compounds. These compounds are included in the calculation of the amount of oxetane in the curable composition.

[0282] The curable composition may further include a compound containing two or more different types of polymerizable heterocycles. For example, the compound may contain one or more oxetane rings and one or more epoxy rings (3-[(oxiranylmethoxy)methyl]oxetane is an example of such a compound). These compounds are included as compounds containing both epoxy and oxetane when calculating the relative amount of oxetane based on the total amount of oxetane and epoxy functional compounds in the curable composition.

[0283] Other cationically curable compounds

[0284] In addition to the oxetane functional compound and the epoxy functional compound, other cationically curable compounds may be included in the curable composition. Non-limiting examples of such compounds include compounds having free hydroxyl groups. The total weight of the cationically curable compounds including the epoxide, oxetane, and free hydroxyl components (such as the hydroxyl groups from SpeedCure S130, the OH from alcohols, polyols, and the OH from (meth)acrylates) should account for 100% of the weight of the cationic system of the curable composition.

[0285] Accordingly, the polyol may optionally be included in the curable composition. As used herein, the term "polymeric polyol" refers to a polymer having two or more primary, secondary or tertiary alcohol groups per molecule. As used herein, the term "non-polymeric polyol" refers to a non-polymeric compound having two or more hydroxyl groups per molecule. In the context of the present invention, the term "polymer" means a compound having five or more repeating units per molecule, and the term "non-polymeric compound" means a compound having at most four repeating units per molecule (and thus includes both monomeric compounds and oligomeric compounds having 2 to 4 repeating units per molecule). For example, ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol are all examples of non-polymeric polyols, while polyethylene glycols containing five or more alkylene oxide repeating units are examples of polymeric polyols.

[0286] Preferably, the hydroxyl group is a primary hydroxyl group and / or a secondary hydroxyl group. In the case where the polyol is a polymeric polyol, according to certain embodiments, the hydroxyl group may be located at the end of the polymer. However, the hydroxyl group may also be present along the main chain of the polymer or on a side chain or a group pendant to the main chain of the polymer. The polymer portion of the polymeric polyol may be composed of a plurality of repeating units, such as alkylene oxide units, ester units, carbonate units, acrylic units, alkylene units, etc. or combinations thereof.

[0287] According to certain embodiments, the polymeric polyol may be represented by the following structure:

[0288] HO-R9-OH

[0289] wherein R9 is a polyether (e.g., polyalkylene oxide), polycarbonate, polybutadiene, polyorganosiloxane or polyester chain or linker.

[0290] Particularly preferred polymeric polyols include polyether diols and polyester diols. Suitable polyether diols include, for example, polytetramethylene glycol (a hydroxyl-functionalized polymer of tetrahydrofuran) and polyethylene glycol (a hydroxyl-functionalized polymer of ethylene oxide). Suitable polyester diols include, for example, poly(ε-caprolactone), poly(lactide), poly(alkylene glycol adipate) and poly(alkylene glycol succinate).

[0291] Other types of polymeric polyols useful in the present invention include polycarbonate polyols, polyorganosiloxane polyols (e.g., polydimethylsiloxane diol or polyol) and polybutadiene polyols (e.g., polybutadiene diol or polyol, including fully or partially hydrogenated polybutadiene polyols).

[0292] The molecular weight of the polymeric polyol can vary as desired or expected in order to achieve specific properties in the cured composition obtained by curing the curable composition. For example, the number average molecular weight of the polymeric polyol can be at least 300 g / mol, at least 350 g / mol, or at least 400 g / mol. In other embodiments, the polymeric polyol can have a number average molecular weight of 5000 g / mol or less, 4500 g / mol or less, or 4000 g / mol or less. For example, the polymeric polyol can have a number average molecular weight of from 250 to 5000 g / mol, from 300 to 4500 g / mol, or from 350 to 4000 g / mol.

[0293] According to certain embodiments of the present invention, the polyol can be represented by the following structure:

[0294] HO-R9-OH

[0295] wherein R9 is a divalent non-polymeric aliphatic moiety that optionally further comprises one or more heteroatoms (such as O, N, S, and / or halogen).

[0296] In certain aspects of the present invention, the diol is or comprises a non-polymeric polyol that is a hydrogenated dimer fatty acid (sometimes also referred to as "dimer diol"), for example, a diol obtained by dimerizing one or more unsaturated fatty acids such as oleic acid or linoleic acid and then hydrogenating to convert the carboxylic acid groups to hydroxyl groups. Pripol 2033 (a product sold by Croda) is an example of a suitable commercially available hydrogenated dimer fatty acid.

[0297] Other types of suitable non-polymeric polyols include, but are not limited to, C2-C12 aliphatic polyols, diols, and their oligomers (containing up to four oxyalkylene repeat units). The aliphatic polyol or diol can be linear, branched, or cyclic in structure, wherein the hydroxyl groups are all primary hydroxyl groups or all secondary hydroxyl groups or one or more of each type (e.g., one primary hydroxyl group and one secondary hydroxyl group).

[0298] Examples of suitable C2-C12 aliphatic diols include, but are not limited to, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2,2,4-trimethyl-1,5-pentanediol, and 2-methyl-2-ethyl-1,3-propanediol, and oligomers thereof containing up to four oxyalkylene repeat units.

[0299] If present, the optional at least one polyol may be selected from ethylene glycol, propylene glycol, 1,3 - propanediol, 1,2 -, 1,3 - or 1,4 - butanediol, 2 - methyl - 1,3 - propanediol (MPDiol), neopentyl glycol, alkoxylated derivatives of the foregoing, polyether diols, polyester diols, polycarbonate diols, and combinations thereof.

[0300] Aliphatic diols (linear, branched or containing a ring structure) may be ethylene glycol, 1,2 - propylene glycol, 1,3 - propylene glycol, 1,4 - butanediol, neopentyl glycol, 2 - ethyl - 1,3 - hexanediol, 1,3 - butanediol, 2 - butyl - 2 - ethyl - 1,3 - propanediol, 2,4 - diethyl - 1,5 - pentanediol, and the like and short - chain oligomers thereof (containing up to four oxyalkylene repeating units). Generally, the hydroxyl groups in such aliphatic diols are primary or secondary hydroxyl groups which will readily react with the diisocyanates used to prepare inherently reactive urethane acrylate oligomers.

[0301] The polyol may be selected from ethylene glycol, propylene glycol, 1,3 - propanediol, 1,2, 1,3 or 1,4 - butanediol, 2 - methyl - 1,3 - propanediol (MPDiol), neopentyl glycol, alkoxylated derivatives thereof, polyether diols, polyester diols or polysiloxane diols, and combinations thereof.

[0302] The cation - curable compound may also be, for example, a cyclic ether compound, a cyclic lactone compound, a cyclic acetal compound, a cyclic thioether compound, a spiroorthoester compound or a vinyl ether compound.

[0303] Hybrid free - radical / cationic composition

[0304] The composition may be a hybrid free - radical / cation - curable composition, i.e., a composition curable by both free - radical polymerization and cationic polymerization.

[0305] Thus, the curable composition may further comprise a free - radically polymerizable compound and an optional free - radical photoinitiator.

[0306] Preferably, the free - radically polymerizable compound comprises at least one ethylenically unsaturated compound, preferably a (meth)acrylate - functionalized compound.

[0307] As used herein, the term “(meth)acrylate-functionalized compound” refers to a monomer containing a (meth)acrylate group, particularly an acrylate group. The term “(meth)acrylate-functionalized compound” herein encompasses compounds containing more than one (meth)acrylate group, such as 2, 3, 4, 5 or 6 (meth)acrylate groups, which are commonly referred to as “oligomers” containing (meth)acrylate groups. The term “(meth)acrylate group” encompasses acrylate groups (-O-CO-CH=CH2) and methacrylate groups (-O-CO-C(CH3)=CH2). Preferably, the (meth)acrylate-functionalized compound does not contain any amino groups. As used herein, the term “amino group” refers to a primary, secondary or tertiary amine group, but does not include any other type of nitrogen-containing group (such as amide, carbamate, urea or sulfonamide groups).

[0308] (Meth)acrylate-functionalized compounds may have a molecular weight of less than 600 g / mol, particularly 100 - 550 g / mol, more particularly 200 - 500 g / mol.

[0309] Based on the total weight of the curable composition, the curable composition may contain 5 wt% to 95 wt%, preferably 8 wt% to 90 wt%, more preferably 10 wt% to 80 wt%, and most preferably 15 wt% to 75 wt% of one or more ethylenically unsaturated compounds. If the composition contains a mixture of ethylenically unsaturated compounds, the above weight percentages may be calculated using the weight of the mixture of ethylenically unsaturated compounds.

[0310] In one embodiment, based on the total weight of the curable composition, the curable composition may contain 40 wt% to 90 wt%, 45 wt% to 85 wt%, 50 wt% to 80 wt% or 50 wt% to 75 wt% of (meth)acrylate-functionalized compounds.

[0311] Alternatively, based on the total weight of the curable composition, the curable composition may contain 5 wt% to 50 wt%, 10 wt% to 45 wt%, 15 wt% to 40 wt% or 15 wt% to 30 wt% of (meth)acrylate-functionalized compounds.

[0312] In addition to compounds containing epoxy groups and oxetanes, suitable ethylenically unsaturated compounds include compounds containing at least one carbon-carbon double bond, especially a carbon-carbon double bond capable of participating in a free radical reaction, where at least one carbon of the carbon-carbon double bond is covalently bonded to an atom, especially a carbon atom, in a second molecule. Such reactions can lead to polymerization or curing, whereby the ethylenically unsaturated compound becomes part of a polymeric matrix or polymeric chain. In various embodiments of the present invention, the additional ethylenically unsaturated compound may contain one, two, three, four, five or more carbon-carbon double bonds per molecule. Combinations of multiple ethylenically unsaturated compounds containing different numbers of carbon-carbon double bonds can be used in the curable composition. The carbon-carbon double bond may be present as part of an α,β-unsaturated carbonyl moiety, such as an α,β-unsaturated ester moiety like an acrylate functional group or a methacrylate functional group, or an α,β-unsaturated amide moiety like an acrylamide functional group or a methacrylamide functional group. The carbon-carbon double bond may also be present in the additional ethylenically unsaturated compound in the form of vinyl -CH=CH2 (e.g., allyl -CH2-CH=CH2). Two or more different types of functional groups containing carbon-carbon double bonds may be present in the additional ethylenically unsaturated compound. For example, the ethylenically unsaturated compound may contain two or more functional groups selected from vinyl (including allyl), acrylate group, methacrylate group, acrylamide group, methacrylamide group, and combinations thereof.

[0313] Ethylenically unsaturated compounds that are suitable as compounds for use in the present invention include compounds of the following types (where "functional" refers to the number of (meth)acrylate functional groups per molecule, e.g., monofunctional = one (meth)acrylate group per molecule, difunctional = two (meth)acrylate groups per molecule):

[0314] i) Cyclic monofunctional (meth)acrylate compounds, such as isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, and their alkoxylated analogs;

[0315] ii) Linear or branched monofunctional (meth)acrylate compounds, such as isodecyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, polyethylene mono(meth)acrylate, neopentyl glycol mono(meth)acrylate, and their alkoxylated analogs, and caprolactone-based monofunctional (meth)acrylate prepared by adding 1, 2, 3 or more moles of caprolactone to a hydroxyalkyl (meth)acrylate such as hydroxyethyl (meth)acrylate ("caprolactone adduct of hydroxyalkyl (meth)acrylate");

[0316] iii) Cyclic difunctional (meth)acrylate compounds, such as tricyclodecane dimethanol di(meth)acrylate, cyclohexane dimethanol di(meth)acrylate, and their alkoxylated analogs;

[0317] iv) linear or branched bifunctional (meth)acrylate compounds, such as polyethylene di(meth)acrylate, neopentyl glycol di(meth)acrylate and their alkoxylated analogues; and

[0318] v) trifunctional (meth)acrylate compounds, such as tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate, trimethylolpropane tri(meth)acrylate and their alkoxylated analogues.

[0319] Illustrative examples of suitable ethylenically unsaturated compounds containing (meth)acrylate functional groups include 1,2-, 1,3- or 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, alkoxylated 1,6-hexanediol di(meth)acrylate, alkoxylated aliphatic di(meth)acrylate, alkoxylated neopentyl glycol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, n-alkyl (meth)acrylate, polyether di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, ethylene glycol di(meth)acrylate, 1,2- or 1,3-propanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyester di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, propoxylated neopentyl glycol diacrylate, tricyclodecane dimethanol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, bis-trimethylolpropane tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol penta / hexa(meth)acrylate, penta(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, alkoxylated trimethylolpropane tri(meth)acrylate, propoxylated glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propoxylated glycerol tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate (also known as tris((meth)acryloyloxyethyl) isocyanurate), 2(2-ethoxyethoxy)ethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, 3,3,5 - Trimethylcyclohexyl (meth)acrylate, alkoxylated lauryl (meth)acrylate, alkoxylated phenol (meth)acrylate, alkoxylated tetrahydrofurfuryl (meth)acrylate, caprolactone (meth)acrylate, (meth)acryloyloxyethyl di(caprolactone), cyclic trimethylolpropane formal (meth)acrylate, alicyclic acrylate compound, dicyclopentadienyl (meth)acrylate, diethylene glycol methyl ether (meth)acrylate, ethoxylated (4) nonylphenol (meth)acrylate, ethoxylated nonylphenol (meth)acrylate, isobornyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, octyldecyl (meth)acrylate, stearyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, tridecyl (meth)acrylate, and / or triethylene glycol ethyl ether (meth)acrylate, tert - butylcyclohexyl (meth)acrylate, alkyl (meth)acrylate, dicyclopentadiene di(meth)acrylate, alkoxylated nonylphenol (meth)acrylate, phenoxyethanol (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, tridecyl (meth)acrylate, cetyl (meth)acrylate, hexadecyl (meth)acrylate, behenyl (meth)acrylate, diethylene glycol ethyl ether (meth)acrylate, diethylene glycol butyl ether (meth)acrylate, triethylene glycol methyl ether (meth)acrylate, 1,12 - dodecanediol di(meth)acrylate, tricyclodecane methanol mono(meth)acrylate, glycerol carbonate (meth)acrylate and their compositions.,

[0320] Suitable polyether (meth)acrylates include, but are not limited to, the condensation reaction products of acrylic acid or methacrylic acid or mixtures thereof with polyether alcohols, where the polyether alcohols are polyether polyols. Suitable polyether alcohols can be straight - chain or branched - chain substances containing ether bonds and terminal hydroxyl groups. Polyether alcohols can be prepared by the ring - opening polymerization of cyclic ethers such as tetrahydrofuran or alkylene oxides with initiator molecules. Suitable initiator molecules include water, hydroxyl - functional materials, polyester polyols, and amines.,

[0321] In certain embodiments, one or more urethane diacrylates may be employed. For example, the curable composition may comprise one or more urethane diacrylates, which include bifunctional aromatic urethane acrylate oligomers, bifunctional aliphatic urethane acrylate oligomers, and combinations thereof. In certain embodiments, bifunctional aromatic urethane acrylate oligomers, such as those commercially available under the trade name CN9782 from Sartomer USA, LLC (Exton, Pennsylvania), may be used as one or more of the urethane diacrylates. In other embodiments, bifunctional aliphatic urethane acrylate oligomers, such as the oligomers commercially available under the trade name CN9023 from Sartomer USA, LLC, may be used as one or more of the urethane diacrylates. CN9782, CN9023, CN978, CN965, CN9031, CN8881, and CN8886 may all be advantageously used as urethane diacrylates in the composition and are all commercially available from Sartomer USA, LLC.

[0322] Suitable acrylic (meth)acrylate oligomers (sometimes also referred to in the art as "acrylic oligomers") include oligomers of materials that can be described as having a polyacrylic backbone functionalized with one or more (meth)acrylate groups, which may be at the termini of the oligomer or as side groups on the acrylic backbone. The acrylic backbone may be a homopolymer, random copolymer, or block copolymer composed of repeating units of acrylic compounds. The acrylic compounds may be any (meth)acrylate, such as C1-C6 alkyl (meth)acrylates and functionalized (meth)acrylates, such as (meth)acrylates bearing hydroxyl, carboxylic acid, and / or epoxy groups. The acrylic (meth)acrylate oligomers may be prepared using any procedure known in the art, such as oligomerizing a compound that is at least partially functionalized with hydroxyl, carboxylic acid, and / or epoxy groups (e.g., hydroxyalkyl (meth)acrylate, (meth)acrylic acid, glycidyl (meth)acrylate) to obtain a functionalized oligomer intermediate, and then reacting it with one or more (meth)acrylate-containing reactants to introduce the desired (meth)acrylate functional groups. Suitable acrylic (meth)acrylate oligomers are commercially available, for example, from Sartomer USA, LLC under the product names CN820, CN821, CN822, and CN823.

[0323] Suitable free (meth)acrylate oligomers include, for example, polyester (meth)acrylates, epoxy (meth)acrylates, polyether (meth)acrylates, polyurethane (meth)acrylates, acrylic (meth)acrylate oligomers, epoxy-functional (meth)acrylate oligomers, and combinations thereof.

[0324] According to certain embodiments, the curable composition comprises one or more ethylenically unsaturated compounds having one or more hydroxyl groups per molecule. Examples of such hydroxyl-containing ethylenically unsaturated compounds include, but are not limited to, caprolactone adducts of (meth)acrylic hydroxyalkyl esters (corresponding to the general formula H2C=C(R)-C(=O)-O-R 1 -(OC(=O)-[(CH2)5] n OH compounds, where R = H, CH3, R 1 = C2-C4 alkylene, such as ethylene, propylene, butylene, and n = 1-10, for example acryloyloxyethyl di(caprolactone)), (meth)acrylic hydroxyalkyl esters, alkoxylated (e.g., ethoxylated and / or propoxylated) (meth)acrylic hydroxyalkyl esters (including mono-(meth)acrylates of ethylene glycol and propylene glycol oligomers and polymers), etc.

[0325] In addition to the above free-radically polymerizable compounds, in this embodiment, the curable composition comprises a free-radical photoinitiator, particularly a free-radical photoinitiator having Norrish type I activity and / or Norrish type II activity, more particularly a free-radical photoinitiator having Norrish type I activity. The free-radical photoinitiator does not match formula (I).

[0326] Non-limiting types of free radical photoinitiators suitable for use in curable compositions include, for example, benzoin, benzoin ethers, acetophenones, α-hydroxyacetophenones, benzil, benzil ketals, phosphine oxides, acylphosphine oxides, α-hydroxy ketones, phenylglyoxylates, α-aminoketones, benzoylformates, acylgermanium compounds, their polymeric derivatives, and mixtures thereof, including but not limited to: benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, α-methylbenzoin, α-phenylbenzoin, Michler’s ketone, 1-hydroxy phenyl ketone, acetophenone, 2,2-diethoxyacetophenone, benzil, α-hydroxy ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,2-dimethoxy-1,2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropanone, 2-hydroxy-2-methyl-1-phenylpropanone, oligo-α-hydroxy ketone, benzoylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate, p-methoxybenzoin, benzoin isobutyl ether, 4-benzoylbiphenyl, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, 4,4'-dimethyldibenzil, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide / 2-hydroxy-2-methylpropiophenone 50 / 50 mixture, 4'-ethoxyacetophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 3'-hydroxyacetophenone, 4'-hydroxyacetophenone, methyl benzoylformate, 4'-phenoxyacetophenone, their polymeric derivatives, and their compositions.

[0327] Preferred free radical photoinitiators are acetophenones, α-hydroxyacetophenones, phosphine oxides, and acylphosphine oxides, more preferably acetophenones and acylphosphine oxides.

[0328] In particular, the free radical photoinitiator can be selected from acetophenones, such as SpeedCure BKL (2,2-dimethoxy-1,2-phenylacetophenone); acylphosphine oxides, such as Speed Cure XKM (ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate), SpeedCure BPO (phenylbis(2,4,6-trimethylbenzoyl)-phosphine oxide), SpeedCure TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide) or SpeedCure TPO-L ((2,4,6-trimethylbenzoyl)phenylphosphinate); and mixtures thereof.

[0329] The amount of the radical photoinitiator can be appropriately varied depending on factors such as the selected radical photoinitiator, the amount and type of polymerizable substances present in the curable composition, the radiation source used, and the radiation conditions. However, generally, based on the total weight of the curable composition, the amount of the radical photoinitiator can be from 0 wt% to 10 wt%, such as from 0.05 wt% to 10 wt%, particularly from 0.1 wt% to 5 wt%, and more particularly from 0.5 wt% to 2 wt% of the radical photoinitiator. For example, based on the total weight of the curable composition, the amount of the radical photoinitiator can be from 0.01 wt% to 5 wt%, from 0.02 wt% to 3 wt%, from 0.05 wt% to 2 wt%, from 0.1 wt% to 1.5 wt% or from 0.2 wt% to 1 wt%. In another example, based on the total weight of the curable composition, the amount of the radical photoinitiator can be from 1 wt% to 5 wt%, from 1.5 wt% to 5 wt%, from 2 wt% to 5 wt%, from 2.5 wt% to 5 wt% or from 3 wt% to 5 wt%.

[0330] Filler

[0331] The curable composition can include at least one filler, such as at least one opaque filler that is insoluble in the other components of the photocurable composition. In particular, such a filler is not dissolved in the curable composition. Further, it is preferred that at least one filler is insoluble in the solid resin matrix formed by curing the curable resin composition. The use of one or more fillers that are insoluble in the cured resin matrix makes it possible to produce composite materials from the curable composition of the present invention.

[0332] The one or more fillers can be in any suitable shape or form. For example, the filler can be in the form of powder, beads, microspheres, granules, pellets, wires, fibers or combinations thereof. If in particulate form, the particles can be spherical, flattened, irregular or elongated in shape. For example, highly aspected particulate fillers can be used. Both hollow and solid fillers can be used in the present invention. According to various embodiments of the present invention, the filler can have an aspect ratio of 1:1 or higher, such as greater than 1:1, at least 2:1, at least 3:1, at least 5:1, at least 10:1, at least 100:1, at least 1000:1; at least 10,000:1, at least 100,000:1, at least 500,000:1, at least 1,000,000:1 or even higher (i.e., effectively infinite aspect ratio). According to other embodiments, the filler can have an aspect ratio of no greater than 2:1, no greater than 3:1, no greater than 5:1, no greater than 10:1, no greater than 100:1, no greater than 1000:1; no greater than 10,000:1, no greater than 100,000:1, no greater than 500,000:1 or no greater than 1,000,000:1.

[0333] The surface of the filler can be modified according to any method or technique known in the art. Such surface treatment methods include, but are not limited to, sizing (e.g., coating with one or more organic substances), silylation, oxidation, functionalization, neutralization, acidification, other chemical modifications, etc. and combinations thereof.

[0334] The chemical nature of the filler can be varied and selected as needed to impart certain properties or characteristics to the product obtained upon curing the photocurable composition. For example, the filler can be inorganic or organic. Mixed organic / inorganic fillers can also be used. Carbon-based fillers (e.g., carbon fibers, carbon black, carbon nanotubes) as well as mineral fillers can be used. One or more fibrous fillers (i.e., fillers in the form of fibers) can be used in particularly preferred embodiments of the present invention. Suitable exemplary fibrous fillers include carbon fibers (sometimes referred to as graphite fibers), glass fibers, silicon carbide fillers, boron fibers, alumina fibers, polymer fibers (e.g., aramid fibers), metal fibers, natural fibers (e.g., fibers derived from plant sources), and combinations thereof. The fibers can be of natural or synthetic origin. Any of the following types of fibers can be used: short fibers (length < 10 mm), chopped fibers, long fibers (length at least 10 mm), continuous fibers, woven continuous fibers, non-woven continuous fibers, woven fiber mats, non-woven fiber mats (e.g., random fiber mats), biaxial mats, unidirectional mats, continuous strands, unidirectional fibers, fiber tows, fiber fabrics, braided fibers, knitted fibers, etc. and combinations thereof. Generally, suitable fibers will have a diameter of about 2 to about 20 microns, e.g., about 5 to about 10 microns. Hollow as well as solid fibers can be used; the cross-section of the fiber can be circular or irregular.

[0335] Examples of other types of fillers that can be used in the curable composition include clays (including organically modified clays and nanoclays), bentonites, silicates (e.g., magnesium silicate, talc, calcium silicate, wollastonite), metal oxides (e.g., zinc oxide, titanium dioxide, alumina), carbonates (e.g., calcium carbonate), mica, zeolites, talc, sulfates (e.g., calcium sulfate), etc. and combinations thereof.

[0336] In one embodiment, the curable composition comprises a relatively high loading of one or more fillers that are not opaque but are capable of scattering the light to which the photocurable composition is exposed. For example, light scattering can occur when the refractive index of the filler is different from the refractive index of the portion of the curable composition that does not include the filler (which is typically a liquid composed of photocurable compounds, a photoinitiator system, and possibly other non-filler additives before curing). Such fillers can include, for example, glass fillers (e.g., glass fibers) and fillers composed of transparent polymers. In such an embodiment, the curable composition can comprise at least 20 wt%, at least 30 wt% or at least 40 wt% of such light-scattering fillers based on the total weight of the curable composition.

[0337] Solvent

[0338] Advantageously, the curable composition can be formulated to be solvent-free, i.e., free of any non-reactive volatile substances. However, in certain other embodiments of the present invention, the curable composition may comprise one or more solvents, particularly one or more organic solvents, which may be non-reactive organic solvents. In various embodiments, the solvent may be relatively volatile, e.g., a solvent having a boiling point of no more than 150 °C at atmospheric pressure. In other embodiments, the solvent may have a boiling point of at least 40 °C at atmospheric pressure.

[0339] One or more solvents can be selected so as to be able to dissolve one or more components of the curable composition and / or to adjust the viscosity or other rheological properties of the curable composition.

[0340] However, the curable composition can alternatively be formulated to contain little or no non-reactive solvent, e.g., less than 10% or less than 5% or even 0% non-reactive solvent, based on the total weight of the curable composition. Such solvent-free or low-solvent compositions can be formulated using various components, including, for example, low-viscosity reactive diluents selected such that the curable composition has a low enough viscosity even in the absence of solvent so that the curable composition can be easily applied to the surface of a substrate at a suitable application temperature to form a relatively thin, uniform layer.

[0341] Suitable solvents can include, for example, organic solvents such as: ketones; esters; carbonates; alcohols; aromatic solvents such as xylene, benzene, toluene, and ethylbenzene; alkanes; ethylene glycol ethers; ethers; amides; and combinations thereof.

[0342] In various embodiments of the present invention, the curable composition described herein is formulated to have a viscosity of less than 10,000 mPa·s (cP), or less than 5,000 mPa·s (cP), or less than 4,000 mPa·s (cP), or less than 3,000 mPa·s (cP), or less than 2,500 mPa·s (cP), or less than 2,000 mPa·s (cP), or less than 1,500 mPa·s (cP), or less than 1,000 mPa·s (cP), or even less than 500 mPa·s (cP), as measured at 25 °C using a Brookfield viscometer, model DV-II, using a #27 spindle (where the spindle speed typically varies between 20 rpm and 200 rpm, depending on the viscosity). In advantageous embodiments of the present invention, the curable composition has a viscosity of 200 cps to 1000 cps at 25 °C.

[0343] Additive

[0344] The curable composition may optionally contain one or more additives in place of or in addition to the above components. Such additives include, but are not limited to, free radical chain transfer agents, antioxidants, ultraviolet absorbers, light blockers, light stabilizers, foam suppression formulations, flow or leveling agents, colorants, pigments, dispersants (wetting agents), slip promoting additives, plasticizers, thixotropic agents, matting agents, impact modifiers, thermoplastics such as acrylic resins without any free radical polymerizable functional groups, waxes or various other additives, including any additives commonly used in the fields of coatings, sealants, adhesives, molding, 3D printing or inks.

[0345] According to a sixth object, the present invention relates to a method for preparing a cured product, comprising curing a curable composition as defined above, preferably by irradiating the composition with at least one light source having a maximum output wavelength in the range of 350 to 460 nm, preferably 365 to 450 nm, particularly 380 to 430 nm, even more preferably 385 nm or 395 nm or 405 nm or 420 nm.

[0346] The light source is typically a light emitting diode (LED), or a broadband lamp with a filter that restricts the emission to wavelengths in the range of 350 to 460 nm.

[0347] The cured product can be a 3D printed article, a coating, an ink, an adhesive, a molding composition and a sealant.

[0348] According to a seventh object, the present invention relates to a 3D printing method, which comprises printing a 3D article with a curable composition as defined above, particularly layer by layer or continuously, preferably by irradiating the composition with at least one light source having a maximum output wavelength of 350 to 460 nm, particularly 380 to 430 nm, even more preferably 385 nm or 395 nm or 405 nm or 420 nm.

[0349] Non-limiting examples of suitable 3D printing processes include stereolithography (SLA); digital light processing (DLP); liquid crystal device (LCD); inkjet head (or multi-jet) printing; continuous liquid interface production (CLIP); extrusion-based processes such as continuous fiber 3D printing and moving cast 3D printing; and volumetric 3D printing. The building method can be "layer by layer" or continuous. The liquid can be in a vat or deposited, for example, by inkjet or gel deposition.

[0350] When stereolithography is performed above an oxygen-permeable build window, the production of articles using a curable composition can be achieved in a CLIP process by creating an oxygen-containing "dead zone", which is a thin uncured layer of the curable composition between the window and the surface at which the cured article is produced. In such a method, a curable composition is used in which curing (polymerization) is inhibited by the presence of molecular oxygen; such inhibition is typically observed, for example, in curable compositions capable of curing by a free-radical mechanism. The desired dead zone thickness can be maintained by selecting various control parameters such as photon flux and the optical and curing properties of the curable composition. The CLIP process proceeds by projecting a continuous sequence of images of actinic radiation (e.g., LED), which can be generated, for example, by a digital light processing imaging unit, through an oxygen-permeable actinic radiation (e.g., LED) transparent window located below a bath of the curable composition maintained in liquid form. The liquid interface below the advancing (growing) article is maintained by the dead zone created above the window. The cured article is continuously withdrawn from the bath of the curable composition above the dead zone, which can be replenished by feeding an additional amount of the curable composition into the bath to compensate for the amount of curable composition cured and incorporated into the growing article.

[0351] In another embodiment, the curable composition will be supplied by jetting it from a printhead rather than from a bucket. This type of process is commonly referred to as inkjet or multi-jet 3D printing. One or more LED curing sources mounted immediately behind the inkjet printhead cure the curable composition immediately after it is applied to the build surface substrate or a previously applied layer. Two or more printheads can be used in this method, which allows different compositions to be applied to different regions of each layer. For example, compositions of different colors or different physical properties can be applied simultaneously to create 3D printed parts of different compositions. In common use, a support material (which is removed during post-processing later) is deposited simultaneously with the composition used to produce the desired 3D printed part. The printhead can be operated at a temperature of about 25 °C to about 100 °C. The viscosity of the curable composition is less than 30 mPa·s at the operating temperature of the printhead.

[0352] In one embodiment, a method for preparing a 3D printed article comprises the steps of:

[0353] a) depositing a first layer of the curable composition as defined above onto a surface;

[0354] b) at least partially curing the first layer according to the method as defined above to provide a cured layer;

[0355] c) depositing a second layer of the curable composition onto the cured first layer;

[0356] d) Cure the second layer at least in part according to the method defined above to provide a cured second layer adhered to the cured first layer; and

[0357] e) Repeat steps c) and d) a desired number of times to build a 3D printed article.

[0358] Before curing, the curable composition can be applied to the surface of the substrate in any known conventional manner, such as by spraying, scraping, roll coating, casting, drum coating, dipping, jetting, extrusion, gel deposition, etc. and combinations thereof. Indirect application using a transfer process can also be used. The substrate can be any commercially relevant substrate, such as a high surface energy substrate or a low surface energy substrate, such as a metal substrate or a plastic substrate, respectively. The substrate can include metals, paper, cardboard, glass, thermoplastics such as polyolefins, polycarbonates, acrylonitrile butadiene styrene (ABS) and blends thereof, composites, wood, leather, and combinations thereof.

[0359] The method can include an additional step f), which includes heating the three-dimensional article to a temperature effective to thermally cure the curable composition.

[0360] After printing the 3D article, it can be subjected to one or more post-treatment steps. The post-treatment steps can be selected from one or more of the following steps: removing any printed support structures, washing with water and / or an organic solvent to remove residual resin, and post-curing using heat treatment and / or actinic radiation, either simultaneously or sequentially. The post-treatment steps can be used to transform the newly printed article into a finished functional article ready for its intended application.

[0361] In one embodiment, a method for preparing a 3D printed article includes the following steps:

[0362] a) Provide a carrier and an optically transparent member having a build surface, the carrier and the build surface defining a build region therebetween;

[0363] b) Fill the build region with the curable composition defined above;

[0364] c) Continuously or intermittently cure a portion of the curable composition in the build region according to the method defined above to form a cured composition; and

[0365] d) Continuously or intermittently advance the carrier away from the build surface to form the 3D printed article from the cured composition.

[0366] The method can further include a post-curing step of heating or microwave irradiating the 3D printed article.

[0367] The above post-treatment steps can also be applied.

[0368] The following examples and drawings illustrate the present invention.

[0369] Figure 1 Figure 1 The acrylate cure conversion of 0.5% Speedcure TPO-L in a hybrid formulation at 405 nm is provided.

[0370] Figure 2 Figure 2 The epoxide cure conversion of 0.5% Speedcure TPO-L in a hybrid formulation at 405 nm is provided.

[0371] Figure 3 Figure 3 The acrylate cure conversion at 405 nm in a hybrid formulation with different radical photoinitiators or without a radical photoinitiator is provided.

[0372] Figure 4 Figure 4 The epoxide cure conversion at 405 nm in a hybrid formulation with different radical photoinitiators or without a radical photoinitiator is provided.

[0373] Figure 5 Figure 5 The total cationic cure conversion at 405 nm in a hybrid formulation with different radical photoinitiators or without a radical photoinitiator is provided.

[0374] Figure 6 Figure 6 The epoxide cure conversion of a cationic formulation at 405 nm is provided.

[0375] Figure 7 Figure 7 The oxetane cure conversion of a cationic formulation at 405 nm is provided.

[0376] Figure 8 Figure 8 The total cationic cure conversion in a cationic formulation is provided.

[0377] Figure 9 Figure 9 The UV spectra of four new sulfonium salts of Omnicat 550, Speedcure 992S (>99% active ingredient), and Speedcure 938 are provided

[0378] Figure 10 Figure 10 ​​​​​​​​​​​​​​​​​​​​The relationship between the curing conversion rate of acrylate or epoxide and the exposure time at 10 mW of a 405 nm LED is provided.

[0379] Example 1: Preparation of the compound of formula (I)

[0380] 1.1. Preparation of the intermediate compound of formula (XXI) (step a))

[0381] The compound of formula (XXI) was prepared following the general procedure 1 below.

[0382] At 0 °C, m-CPBA (1.804 mmol) was slowly added to a solution of the diaryl sulfide of formula (XX) (1.64 mmol) in dichloromethane (10 mL). The mixture was stirred at 0 °C for 4 h, then gradually warmed to room temperature and stirred for 16 h. A saturated aqueous sodium bicarbonate solution was added, and the aqueous layer was then extracted with dichloromethane (3 × 3 mL). The combined organic layers were washed with brine, dried over magnesium sulfate, filtered under reduced pressure, and concentrated. The resulting residue was purified by silica gel column chromatography (PE / AcOEt) to give the diaryl sulfoxide compound of formula (XXI).

[0383]

[0384] [4-(4-Methylphenyl-1-sulfinyl)phenyl](phenyl)methanone

[0385] Prepared from {4-[(4-methylphenyl)thio]phenyl}(phenyl)methanone using general procedure 1. Yield 73%, white solid. Melting point 143 - 144 °C.

[0386] 1 1H-NMR (400 MHz, CDCl3): 7.86 (d, J = 8.2 Hz, 2 H), 7.78 - 7.74 (m, 4H), 7.60 (tt, J = 7.3, 1.4 Hz, 1H), 7.58 (d, J = 8.2 Hz, 2H), 7.50 - 7.46 (m,2H), 7.29 (d, J = 8.2 Hz, 2H), 2.38 (s, 3H).

[0387]

[0388] 2-(Propan-2-yl)-10λ 4 -thioxanthene-9,10-dione

[0389] Prepared from 2-(propan-2-yl)-9H-thioxanthen-9-one using general procedure 1. Yield 54%, pale yellow solid. Melting point: 68 - 70 °C.

[0390] 1 H-NMR (400 MHz, CDCl3): 8.37 (dd, J = 7.8, 1.4 Hz, 1 H), 8.24 (d, J =1.8 Hz, 1 H), 8.16 (dd, J = 8.0, 1.1 Hz, 1 H), 8.09 (d, J = 8.2 Hz, 1 H),7.85 (td, J = 7.6, 1.4 Hz, 1 H), 7.74 - 7.70 (m, 2 H), 3.09 (septet, J = 6.9Hz, 1 H), 1.33 (d, J = 6.9 Hz, 6 H).

[0391]

[0392] 1-chloro-4-propoxy-10λ 4 -thioxanthene-9,10-dione

[0393] Prepared from 1-chloro-4-propoxy-9H-thioxanthen-9-one using General Procedure 1. Yield 61%, yellow solid. Melting point 165 - 166 °C.

[0394] 1 H-NMR (400 MHz, CDCl3): 8.20 - 8.15 (m, 1 H), 7.96 - 7.91 (m, 1 H),7.77 - 7.70 (m, 2 H), 7.62 (d, J = 9.2 Hz, 1 H), 7.18 (d, J = 8.7 Hz, 1 H),4.21 - 4.10 (m, 2 H), 2.02 – 1.93 (m, 2 H), 1.15 (t, J = 7.6 Hz, 3 H).

[0395]

[0396] Methyl [(9,10-dioxo-9,10-dihydro-10λ 4 -thioxanthen-2-yl)oxy]acetate

[0397] Prepared from methyl [(9-oxo-9H-thioxanthen-2-yl)oxy]acetate using General Procedure 1. Yield 81%, light yellow solid.

[0398] 1H-NMR (400 MHz, CDCl3): 8.35 (d, J = 7.8 Hz, 1 H), 8.14 (d, J = 7.8Hz, 1 H), 8.07 (d, J = 8.7 Hz, 1 H), 7.85 (t, J = 7.6 Hz, 1 H), 7.78 (d, J =2.3 Hz, 1 H), 7.71 (t, J = 7.8 Hz, 1H), 7.42 (dd, J = 8.7, 2.3 Hz, 1 H), 4.80(s, 2 H), 3.82 (s, 3 H).

[0399]

[0400] 2,4 - Diethyl - 10λ 4 - thioxanthene - 9,10 - dione

[0401] Prepared from 2,4-diethyl-9H-thioxanthen-9-one using General Procedure 1. Yield 62%, yellow solid. Melting point 99 - 100 °C.

[0402] 1 H-NMR (400 MHz, CDCl3): 8.38 (dd, J = 7.8, 1.4 Hz, 1H), 8.13 (d, J =1.8 Hz, 1H), 8.05 (dd, J = 7.8, 1.4 Hz, 1H), 7.82 (td, J = 7.3, 1.4 Hz, 1H),7.74 (td, J = 7.3, 1.4 Hz, 1H), 7.48 (d, J = 1.8 Hz, 1H), 3.35 - 3.18 (m, 2H),2.78 (q, J = 7.8 Hz, 2H), 1.30 (t, J = 7.6 Hz, 3H), 1.44 (t, J = 7.6 Hz, 3H).

[0403] 1.2. Preparation of the intermediate compound of formula (I) wherein Y y- is PF6 - (Steps b) and c))

[0404] Step b):

[0405] Prepare the compound of formula (I) following General Procedure 2 below.

[0406] Dissolve the appropriate aromatic sulfoxide of formula (XXI) (0.312 mmol) in anhydrous dichloromethane (2.8 mL), and cool the resulting solution to about -60 °C to -50 °C. Then add trifluoromethanesulfonic anhydride (0.3432 mmol), which serves as an activator, to the solution, and stir the mixture at a temperature of -60 °C to -50 °C for 20 min. Add the appropriate aromatic compound of formula (XXII) or (XXV) (0.312 mmol), and gradually warm the mixture to room temperature over 15 hours. Remove the solvent under reduced pressure, and wash the residue with diethyl ether (2 3 mL) to obtain the crude sulfonium trifluoromethanesulfonate intermediate of formula (I), where Y y- is CF3SO3 - .

[0407] Further purification is achieved by silica gel column chromatography (eluting with dichloromethane / methanol).

[0408] Step c):

[0409] In the example, the anion Y in the desired compound of formula (I) y- is PF6 - .

[0410] Remove the solvent under vacuum, and dissolve the residue in water (10 mL) at room temperature. Add a solution of sodium hexafluorophosphate (1.2 moleq.) in water (1 mL), then add chloroform (10 mL), and stir the mixture at room temperature overnight. Separate the organic layer, and extract the aqueous phase with chloroform (2 × 5 mL). Evaporate the solvent to obtain the sulfonium hexafluorophosphate compound of formula (I), where Y y- is PF6 - .

[0411]

[0412] 9-oxo-10-[9-oxo-7-(propan-2-yl)-9H-thioxanthen-2-yl]-2-(propan-2-yl)-9H-thioxanthen- 10-ium hexafluorophosphate(1) (Comparative Example)

[0413] Prepared from 2-(propan-2-yl)-10λ 4 -thioxanthene-9,10-dione and 2-(propan-2-yl)-9H-thioxanthene-9-one using General Procedure 2; yield 28%; orange solid.

[0414] 1H-NMR (400 MHz, CDCl3): 8.68 - 8.65 (m, 1H), 8.55 - 8.50 (m, 2H), 8.25 - 8.20 (m, 3H), 8.14 (d, J = 8.2 Hz, 1H), 8.01 - 7.99 (m, 2H), 7.86 - 7.83 (m, 2H), 7.55 (dd, J = 8.2, 1.8 Hz, 1H), 7.48 (d, J = 8.2 Hz, 1H), 3.15 (septet, J = 6.9 Hz, 1H), 2.99 (septet, J = 6.9 Hz, 1H), 1.36 - 1.33 (m, 6H), 1.25 (d, J = 6.9 Hz, 6H).

[0415] FT-IR (ATR; cm -1 ): 505 (w), 531 (m), 556 (s), 631 (w), 640 (w), 688 (w), 713 (w), 741 (m), 752 (m), 782 (m), 834 (vs), 875 (w), 1061 (w), 1126 (w), 1206 (w), 1239 (w), 1265 (w), 1286 (w), 1300 (w), 1390 (w), 1416 (w), 1442 (w), 1472 (w), 1575 (w), 1590 (w), 1640 (w), 1671 (w), 2962 (w).

[0416] TOF MS ES+ m / z 507.1 Da (exact mass 557.1444 Da).

[0417]

[0418] (4-benzoylphenyl)(4-methylphenyl)[9-oxo-7-(propan-2-yl)-9H-thioxanthen-2-yl]sulfonium hexafluorophosphate (2)

[0419] Prepared from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and 2-(propan-2-yl)-9H-thioxanthen-9-one using General Procedure 2; yield 39%; orange solid.

[0420] 11H-NMR (400 MHz, CDCl3): δ 8.82 (d, J = 2.3 Hz, 1H), 8.34 (d, J = 2.3 Hz, 1H), 8.06 - 7.96 (m, 4H), 7.81 - 7.79 (m, 3H), 7.74 - 7.72 (m, 2H), 7.62 - 7.47 (m, 8H), 3.04 (septet, J = 6.9 Hz, 1H), 2.48 (s, 3H), 1.30 (d, J = 6.9 Hz, 6H).

[0421] FT-IR (ATR; cm -1 -1): 532 (m), 556 (s), 580 (w), 610 (w), 633 (w), 643 (w), 661 (w), 698 (w), 731 (w), 747 (w), 782 (m), 830 (vs), 876 (w), 926 (w), 1012 (w), 1061 (w), 1075 (w), 1126 (w), 1189 (w), 1205 (w), 1274 (m), 1310 (w), 1317 (w), 1397 (w), 1416 (w), 1448 (w), 1472 (w), 1579 (w), 1640 (w), 1660 (w), 2870 (vw), 2961 (vw).

[0422] TOF MS ES+ m / z 557.2 Da (Exact mass 557.1597 Da).

[0423]

[0424] (4-benzoylphenyl)(8-chloro-9-oxo-5-propoxy-9H-thioxanthen-2-yl)(4-methylphenyl)sulfonium hexafluoro phosphate(3)

[0425] Prepared from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and 1-chloro-4-propoxythioxanthen-9-one; yield 54%; yellow solid.

[0426] 11H-NMR (400 MHz, CDCl3): δ 8.64 (J = 2.3 Hz, 1H), 8.07 (dd, J = 8.7, 2.3 Hz, 1H), 8.02 (d, J = 8.2 Hz, 2H), 7.94 (d, J = 8.7 Hz, 1H), 7.81 - 7.79 (m, 4H), 7.72 (d, J = 8.3 Hz, 2H), 7.60 - 7.55 (m, 3H), 7.51 - 7.48 (m, 2H), 7.42 (d, J = 8.7 Hz, 1H), 7.05 (d, J = 8.7 Hz, 1H), 4.10 (t, J = 6.4 Hz, 2H), 2.49 (s, 3H), 1.91 (sextet, J = 7.3 Hz, 2H), 1.11 (t, J = 7.8 Hz, 3H).

[0427] FT-IR (ATR; cm -1 -1): 508 (w), 528 (w), 556 (s), 633 (w), 652 (w), 662 (m), 698 (m), 732 (w), 748 (w), 788 (m), 809 (s), 835 (vs), 876 (w), 926 (w), 958 (w), 1012 (w), 1063 (w), 1178 (w), 1189 (w), 1255 (m), 1275 (m), 1308 (w), 1397 (w), 1433 (w), 1448 (w), 1457 (w), 1546 (w), 1577 (w), 1653 (w), 2877 (w), 2967 (w), 3068 (w).

[0428] TOF MS ES+ m / z 607.1 Da (exact mass 607.1163 Da).

[0429]

[0430] (4-benzoylphenyl)(5,7-diethyl-9-oxo-9H-thioxanthen-2-yl)(4-methylphenyl)sulfonium hexafluorophos phate(4)

[0431] Prepared from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and 2,4-diethyl-9H-thioxanthen-9-one using General Procedure 2; yield 41%; orange solid.

[0432] 1 H-NMR (400 MHz, CDCl3): δ 8.81 (d, J = 2.8 Hz, 1H), 8.20 (d, J = 1.8 Hz, 1H), 8.03 - 8.01 (m, 3H), 7.82 - 7.79 (m, 3H), 7.75 - 7.73 (m, 2H), 7.61 - 7.55 (m, 4H), 7.50 - 7.43 (m, 4H), 2.86 (q, J = 7.3 Hz, 2H), 2.75 (q, J = 7.3 Hz, 2H), 2.48 (s, 3H), 1.35 (t, J = 7.3 Hz, 3H), 1.28 (t, J = 7.3 Hz, 3H).

[0433] FT-IR (ATR; cm -1 ): 476 (w), 516 (w), 556 (s), 633 (w), 661 (m), 699 (m), 731 (m), 748 (w), 782 (m), 833 (vs), 876 (w), 926 (w), 1059 (w), 1190 (w), 1275 (w), 1310 (w), 1397 (w), 1426 (w), 1447 (w), 1579 (w), 1639 (w), 1660 (w), 2967 (vw).

[0434] TOF MS ES+ m / z 571.2 Da (exact mass 571.1760 Da).

[0435]

[0436] 1-chloro-10-(8-chloro-9-oxo-5-propoxy-9H-thioxanthen-2-yl)-9-oxo-4-propoxy-9H-thioxanthen- 10-ium hexafluorophosphate(5) (Comparative Example)

[0437] Prepared from 1-chloro-4-propoxy-10λ 4 -thioxanthene-9,10-dione and 1-chloro-4-propoxy-9H-thioxanthene-9-one using General Procedure 2; yield 30%; yellow solid.

[0438] 1H-NMR (400 MHz, DMSO-d6): 9.15 (d, J = 2.3 Hz, 1 H), 8.49 - 8.44 (m,1 H), 8.22 - 8.17 (m, 1 H), 8.09 (d, J = 9.2 Hz, 1 H), 8.06 (d, J = 9.2 Hz, 1H), 8.02-7.94 (m, 3H), 7.71 (d, J = 9.2 Hz, 1 H), 7.62 (d, J = 9.2 Hz, 1 H),7.43 (d, J = 8.7 Hz, 1 H), 4.23-4.08 (m, 4H), 1.79 (sextet, J = 7.3 Hz, 2H),1.68 (sextet, J = 6.9 Hz, 2H), 1.02 (t, J = 7.8 Hz, 3H), 0.93 (t, J = 7.3 Hz,3H).

[0439] FT-IR (ATR; cm -1 ): 495 (w), 534 (w), 546 (w), 557 (s), 644 (w), 651(w), 687 (w), 694 (w), 718 (w), 742 (w), 761 (m), 773 (w), 799 (m), 808 (s),820 (s), 836 (vs), 882 (w), 935 (w), 975 (w), 1058 (m), 1176 (w), 1238 m),1254 (m), 1265 (m), 1276 (m), 1289 (w), 1303 (m), 1394 (w), 1435 (w), 1443(w), 1549 (w), 1558 (w), 1571 (w), 1663 (w), 1683 (w), 2877 (w), 2959 (w),3082 (w).

[0440] TOF MS ES+m / z 607.1 Da (Exact mass 607.0566 Da).

[0441]

[0442] (4-benzoylphenyl)(4-methylphenyl)(2,4,6-trimethoxyphenyl)sulfonium hexafluorophosphate(7)

[0443] Prepared using General Procedure 2 from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and 1,3,5-trimethoxybenzene; yield 48%; brown semi-solid.

[0444] 1 1H-NMR (300 MHz, CDCl3): 7.97 - 7.94 (m, 2H), 7.82 - 7.79 (m, 2H), 7.66 - 7.48 (m, 9H), 6.32 (s, 2H), 3.95 (s, 3H), 3.83 (s, 6H), 2.48 (s, 3H).

[0445] 19 19F-NMR (282 MHz, CDCl3): -73.35 ppm (J (P-F) = 712.4 Hz).

[0446]

[0447] 9-oxo-2-(propan-2-yl)-10-(2,4,6-trimethoxyphenyl)-9H-thioxanthen-10-ium hexafluorophosphate (8) (Comparative Example)

[0448] Prepared using General Procedure 2 from 2-(propan-2-yl)-10λ 4 -thioxanthene-9,10-dione and 1,3,5-trimethoxybenzene; yield 72%; brown semi-solid.

[0449] 1 1H-NMR (300 MHz, CDCl3): 8.56 - 8.53 (m, 1H), 8.39 (d, J = 1.9 Hz, 1H), 7.95 - 7.86 (m, 2H), 7.82 - 7.72 (m, 3H), 6.20 (s, 2H), 3.88 (s, 3H), 3.74 (br s, 6H), 3.12 (septet, J = 6.9 Hz, 1H), 1.33 (d, J = 6.9 Hz, 6H).

[0450] 19 19F-NMR (282 MHz, CDCl3): -73.40 ppm (J (P-F) = 712.4 Hz).

[0451]

[0452] (4-benzoylphenyl)(4-methylphenyl)(4-phenoxyphenyl)sulfonium hexafluorophosphate(9)

[0453] Prepared using General Procedure 2 from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and diphenyl ether; yield 26%; pale yellow semi-solid.

[0454] Note: The product is a mixture of para- and ortho-isomers (ca. 10:1).

[0455] Major isomer: 1 1H-NMR (300 MHz, CDCl3): 8.02 - 7.99 (m, 2 H), 7.85 - 7.82 (m, 2H), 7.72 - 7.69 (m, 4H), 7.65 - 7.62 (m, 4H), 7.55 - 7.52 (m, 4H), 7.44 - 7.42 (m, 2H), 7.23 - 7.20 (m, 2H), 7.12 - 7.08 (m, 2H), 2.49 (s, 3H).

[0456] 19 19F-NMR (282 MHz, CDCl3): -72.44 ppm (J (P-F) = 713.4 Hz).

[0457] TOF MS ES+ m / z 473.2 Da (exact mass 473.1570 Da).

[0458]

[0459] (1-benzofuran-2-yl)(4-benzoylphenyl)(4-methylphenyl)sulfonium hexafluorophosphate(10)

[0460] Prepared using General Procedure 2 from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and benzofuran; yield 14%; orange semi-solid.

[0461] Note: The product is a mixture of 2- and 3-regioisomers.

[0462] Major isomer: 1 1H-NMR (300 MHz, CDCl3): 8.24 - 6.86 (m, 18H), 2.39 (s, 3H).

[0463] TOF MS ES+ m / z 421.1 Da (exact mass 421.1257 Da).

[0464]

[0465] (4-benzoylphenyl)(4-methylphenyl)[4-(pyrrolidin-1-yl)phenyl]sulfonium hexafluorophosphate(11)

[0466] Prepared using General Procedure 2 from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and 1-phenylpyrrolidine; yield 8%; dark pink solid. Note: The product is a mixture of regioisomers.

[0467] Major isomer: 1 1H-NMR (300 MHz, CDCl3): 7.96 (d, J = 8.1 Hz, 2H), 7.80 (d, J = 7.5 Hz, 2H), 7.68 (d, J = 8.1 Hz, 2H), 7.65 - 7.45 (m, 5H), 7.29 - 7.27 (m, 2H), 7.18 - 7.11 (m, 2H), 6.74 (d, J = 9.3 Hz, 2H), 3.39 - 3.35 (m, 4H), 2.46 (s, 3H), 2.07 - 2.03 (m, 4H).

[0468] TOF MS ES+ m / z 450.2 Da (Exact mass 450.1885 Da).

[0469]

[0470] (4-benzoylphenyl)(4-benzylphenyl)(4-methylphenyl)sulfonium hexafluorophosphate(18)

[0471] Prepared using General Procedure 2 from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and diphenylmethane; yield 19%; yellow semi-solid.

[0472] Note: The product is a mixture of the desired product and (4-benzoylphenyl){2-[(4-benzoylphenyl)sulfanyl]-5-methylphenyl}(4-methylphenyl)sulfonium hexafluorophosphate.

[0473] Major component (56%): TOF MS ES+ m / z 471.2 Da (Exact mass 471.1773 Da).

[0474] Minor component (44%): TOF MS ES+ m / z 607.2 Da (Exact mass 607.1760 Da).

[0475]

[0476] (4-benzoylphenyl)(dibenzo[b,d]furan-2-yl)(4-methylphenyl)sulfonium hexafluorophosphate(19)

[0477] Prepared using General Procedure 2 from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and dibenzofuran; yield 52%; light yellow semi-solid.

[0478] 1 H-NMR (300 MHz, CDCl3): 8.30 (d, J = 8.1 Hz, 1H), 8.07 - 8.00 (m, 3H), 7.95 (d, J = 1.9 Hz, 1H), 7.89 - 7.81 (m, 5H), 7.77 - 7.74 (m, 2H), 7.64 - 7.62 (m, 3H), 7.56 - 7.52 (m, 4H), 7.49 - 7.45 (m, 1H), 2.50 (s, 3H).

[0479] TOF MS ES+ m / z 471.1 Da (exact mass 471.1414 Da).

[0480]

[0481] (4-benzoylphenyl)(dibenzo[b,d]thiophen-2-yl)(4-methylphenyl)sulfonium hexafluorophosphate(20)

[0482] Prepared from [4-(4-methylbenzene-1-sulfinyl)phenyl](phenyl)methanone and dibenzothiophene using General Procedure 2; yield 26%; pale yellow solid. Note: The product is a mixture of the desired product and (4-benzoylphenyl){2-[(4-benzoylphenyl)thio]-5-methylphenyl}(4-methylphenyl)sulfonium hexafluorophosphate.

[0483] Major component (72%): TOF MS ES+ m / z 487.1 Da (exact mass 487.1183 Da).

[0484] Minor component (28%): TOF MS ES+ m / z 607.2 Da (exact mass 607.1760 Da).

[0485]

[0486] (1-benzothiophen-2-yl)(4-benzoylphenyl)(4-methylphenyl)sulfonium hexafluorophosphate(21)

[0487] Prepared from [4-(4-methylbenzene-1-sulfinyl)phenyl](phenyl)methanone and benzothiophene using General Procedure 2; yield 47%; grey solid.

[0488] Note: The product is a mixture of regioisomers.

[0489] 1 H-NMR (300 MHz, CDCl3): 8.20 - 7.51 (m, 18H), 2.51 (s, 3H).

[0490]

[0491] (4-benzoylphenyl)(4'-methoxy[1,1'-biphenyl]-4-yl)(4-methylphenyl)sulfonium hexafluorophosphate (25)

[0492] Prepared using General Procedure 2 from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and 4-methoxybiphenyl; yield 37%; light yellow solid.

[0493] 1 H-NMR (300 MHz, CDCl3): 7.97 (d, J = 8.1 Hz, 2H), 7.86 - 7.73 (m, 9H), 7.59 - 7.43 (m, 8H), 6.94 (d, J = 8.7 Hz, 2H), 3.81 (s, 3H), 2.43 (s, 3H).

[0494] TOF MS ES+ m / z 487.2 Da (exact mass 487.1723 Da).

[0495]

[0496] (4-benzoylphenyl)(2',6-dimethoxy[1,1'-biphenyl]-3-yl)(4-methylphenyl)sulfonium hexafluorophosph ate(27)

[0497] Prepared using General Procedure 2 from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and 2,2'-dimethoxy-1,1'-biphenyl; yield 37%; light blue semi-solid.

[0498] 1 H-NMR (300 MHz, CDCl3): 7.98 (d, J = 8.7 Hz, 2H), 7.85 - 7.78 (m, 3H), 7.72 (d, J = 8.1 Hz, 2H), 7.64 (d, J = 8.1 Hz, 2H), 7.63 - 7.58 (m, 1H), 7.53 - 7.47 (m, 5H), 7.38 - 7.32 (m, 2H), 7.24 (dd, J = 7.5, 1.9 Hz, 1H), 7.01 - 6.96 (m, 2H), 3.87 (s, 3H), 3.73 (s, 3H), 2.46 (s, 3H).

[0499] TOF MS ES+ m / z 517.2 Da (exact mass 517.1829 Da).

[0500]

[0501] (6,6'-dimethoxy[1,1'-biphenyl]-3,3'-diyl)bis[(4-benzoylphenyl)(4-methylphenyl) sulfonium] bishexafluorophosphate(29)

[0502] Prepared using General Procedure 2 from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and (4-benzoylphenyl)(2',6-dimethoxy[1,1'-biphenyl]-3-yl)(4-methylphenyl)sulfonium trifluoromethanesulfonate; yield 44%; pale purple semi-solid.

[0503] 1 H-NMR (300 MHz, CDCl3): 7.97 (d, J = 8.1 Hz, 4H), 7.81 - 7.66 (m, 16H), 7.61 - 7.56 (m, 2H), 7.53 - 7.45 (m, 8H), 7.27 (d, J = 8.7 Hz, 2H), 3.79 (s, 6H), 2.44 (s, 6H).

[0504] TOF MS ES+ m / z 410.1 Da (exact mass 410.1335 Da).

[0505]

[0506] (4-benzoylphenyl)[7-(2-methoxy-2-oxoethoxy)-9-oxo-9H-thioxanthen-2-yl](4-meth ylphenyl)sulfonium hexafluorophosphate(41)

[0507] Prepared using General Procedure 2 from [4-(4-methylbenzenesulfinyl)phenyl](phenyl)methanone and methyl [(9-oxo-9H-thioxanthen-2-yl)oxy]acetate; yield 26%; yellow solid.

[0508] Note: The product is a mixture of the desired product and (4-benzoylphenyl){2-[(4-benzoylphenyl)thio]-5-methylphenyl}(4-methylphenyl)sulfonium hexafluorophosphate.

[0509] Major component: 1 H-NMR (300 MHz, CDCl3): 8.81 - 8.80 (m, 1H), 8.12 - 7.42 (m, 18H), 4.79 (s, 2H), 3.83 (s, 3H), 2.52 (s, 3H).

[0510] Major component (71%): TOF MS ES+ m / z 603.1 Da (exact mass 603.1294 Da).

[0511] Minor component (29%): TOF MS ES+ m / z 607.2 Da (exact mass 607.1760 Da).

[0512] Example 2: Curing Properties of the Compounds of Example 1

[0513] 2.1. Curing Performance at 365 and 385 nm

[0514] The curing performance of each of the above-prepared products was evaluated using real-time FT-IR measurements. The photoinitiator was dissolved in the alicyclic epoxy UViCure S105 (purchased from Sartomer) at the specified weight % loading, applied to an FT-IR measurement plate, and irradiated with the specified LED light source. The polymerization rate and the final reactive group conversion were determined by monitoring the change in the relevant infrared spectral band corresponding to the epoxy ring near 900 cm -1 The molar extinction coefficient (ε, expressed in M -3 M or 10 - 5 cm -1 cm -1 ) of the photoinitiator product was determined at a concentration of 10

[0515] [Table 1]

[0516]

[0517] Table 1: Curing Performance of Compounds Evaluated Using Real-Time FT-IR Measurements at 365 and 385 nm

[0518] 2.2. Curing Performance at 405 nm

[0519] The curing performance of each of the above-prepared products was evaluated using real-time FT-IR measurements. As shown, the photoinitiator was dissolved in pure trimethylolpropane triacrylate (TMPTA, purchased from Sartomer as SR351) or dissolved in a 1:1 (w / w) mixture of TMPTA and Uvicure S 105, applied to an FT-IR measurement plate, laminated to prevent oxygen inhibition, and irradiated with the indicated LED light source. For the epoxy component, the polymerization rate and the final reactive group conversion were determined by monitoring the change in the relevant infrared spectral band corresponding to the epoxy ring near 900 cm -1 The acrylate component used the C=C stretching band near 1625 cm -1 .

[0520] [Table 2]

[0521] Table 2: Curing Performance of Compounds Evaluated Using Real-Time FT-IR Measurements at 405 nm

[0522] 2.3. Belt curing performance at 365 nm and 395 nm

[0523] The photoinitiator was dissolved in pure Uvicure S 105E resin or a hybrid acrylate / epoxy (prepared by mixing 60 parts by weight of Uvicure S 105E, 15 parts by weight of Uvicure S 130, and 25 parts by weight of SR 492, all products were purchased from Sartomer). Formulations were prepared by combining all materials in a given ratio and then stirring at 30 - 40 °C until the sample was completely homogeneous; then the formulation was cooled to room temperature. For all experiments, the formulations were cured on Leneta Form 3N - 31 gloss finish paper at 6 μm and 24 μm film thicknesses using a belt curing instrument; K - bars were used to prepare the films. Then all the films were cured under an LED lamp at a given belt speed. A "thumb - twist" test (where no visible mark was formed when the thumb was firmly pressed down onto the coating in a twisting motion) and the "depth of cure" of each formulation were evaluated based on the belt speed; the calculated cure speed (in m / min) was given.

[0524] [Table 3]

[0525] Table 3: Belt curing performance at 365 nm

[0526] [Table 4]

[0527]

[0528] Table 4: Belt curing performance at 395 nm

[0529] From these results, it can be seen that the sulfonium salt photoinitiators according to the present invention are effective photoinitiators for epoxy, acrylic, and hybrid resin formulations under LED lamp conditions.

[0530] In particular, photoinitiators 2 and 4 showed higher cure speeds than photoinitiators known in the prior art such as Omnicat BL 550.

[0531] Photoinitiator 5 showed a higher cure speed than photoinitiators known in the prior art such as Omnicat BL 550.

[0532] Photoinitiators 26 and 32 showed higher cure speeds than photoinitiators known in the prior art such as Omnicat BL 550.

[0533] Photoinitiators 14 and 30 showed higher cure speeds than photoinitiators known in the prior art such as Omnicat BL 550.

[0534] Example 3: Other properties of the compound of Example 1

[0535] 3.1. Color measurement

[0536] Prepare a formulation containing a photoinitiator and neat UViCure S105E resin as described in Example 2.

[0537] [Table 5]

[0538] Table 5: Color index 'b' of formulations containing the compound and irradiated at 365 or 385 nm

[0539] 3.2. Solubility data

[0540] Determine the solubility of the selected sulfonium salts in propylene carbonate at ambient temperature (20 - 25 °C).

[0541] [Table 6]

[0542] Table 6: Solubility of the compound in propylene carbonate at 20 - 25 °C

[0543] 3.3. Thermal stability determined by DSC

[0544] Prepare a formulation containing a photoinitiator and neat UViCure S105E resin and / or TMPTA resin as described in Example 2.

[0545] [Table 7]

[0546] Table 7: Thermal stability of formulations containing UViCure S105E resin and the compound

[0547] [Table 8]

[0548] Table 8: Thermal stability of formulations containing TMPTA resin or TMPTA / UViCure S105E resin and the compound

[0549] 3.4. Transmittance data

[0550] Prepare samples at 0.01% w / v in propylene carbonate.

[0551] [Table 9]

[0552] Table 9: Transmittance of samples containing 0.01% w / v compound in propylene carbonate.

[0553] 3.5. 6-Month Stability Study and Reference

[0554] [Table 10]

[0555] *The hybrid resin used has the following composition: 60 wt% of UViCure S105E / 15 wt% of UViCure S130 / 25 wt% of Sartomer SR492

[0556] Table 10: 6 months Stability Study of the Formulation

[0557] Example 4: Curing Performance in Cationic and Hybrid Formulations and 3D Printability in Hybrid Systems

[0558] 4.1. Materials and Structure

[0559] [Table 11]

[0560]

[0561]

[0562]

[0563] Table 11: Materials Used and Their Suppliers

[0564] 4.2 Sample Preparation and Test Methods

[0565] [Table 12]

[0566] HEx: High Epoxide Matrix

[0567] LEx: Low Epoxide Matrix

[0568] CMx: Cationic Monomer Matrix

[0569] Table 12: Overview of the Matrix

[0570] [Table 13]

[0571] Table 13: 0.5% TPO-L in the Hybrid Formulation and Its Curing Performance

[0572] [Table 14]

[0573] Table 14: 0.5% XKm in the Hybrid Formulation and Its Curing Performance

[0574] [Table 15]

[0575] Table 15: 0.5% TPO in Hybrid Formulations and Its Curing Properties

[0576] [Table 16]

[0577] Table 16: 0.5% BPO in Hybrid Formulations and Its Curing Properties

[0578] [Table 17]

[0579] Table 17: 0.5% BKL in Hybrid Formulations and Its Curing Properties

[0580] [Table 18]

[0581]

[0582] Table 18: No Free Radical Photoinitiator in Hybrid Formulations and Its Curing Properties

[0583] [Table 19]

[0584] Table 19: No Free Radical Initiator in Cationic Formulations and Its Characteristics

[0585] [Table 20]

[0586] Table 20: 0.5% TPO-L in Cationic Formulations and Its Properties

[0587] [Table 21]

[0588] Table 21: 0.5% BKL in Cationic Formulations and Its Properties

[0589] Preparation of Matrices and Formulations in Tables 12 to 21

[0590] Matrix: In a 1000 mL metal can, load the formulation matrix according to the percentages in Table 12. Prepare a 1000 - 1005 g mixture of each matrix sample and mix it with a mechanical mixer at about 60 °C for about 1 hour until the solution becomes clear.

[0591] Formulation: In a white max 50 wide-mouth bottle from FlackTek Inc., first load the photoinitiator and propylene carbonate, manually mix with a stainless-steel spatula, place in a 60 °C oven for about 1 hour, and mix again until it becomes transparent. Then, load the formulation matrix according to one of the percentages in Tables 13 to 21. Prepare 51.25.5 - 52.60 g of the mixture for each sample and mix in a Speed Mixer from FleackTec Inc. at 3000 rpm for 3 minutes. Then, place all the wide-mouth bottles in a 60 °C oven for about 2 hours, take out and immediately remix for 2 minutes until the solution becomes clear.

[0592] FTIR Test

[0593] Use Fourier transform infrared (FTIR) with an attenuated total reflection (ATR) device. All polymerization rate measurements were carried out using a Nicolet iS50 FT-IR spectrometer from ThermoScientific equipped with a standard DLaTGS detector. The lamp holder of the ART platform of the FTIR unit can be customized and printed with Arkema N 3xtDimension engineering resin N3D-TOUGH784 to ensure an exact fit with the 365 nm lamp Accucure ULM-2-365 or 405 nm lamp Accucure ULM-2-405 from Digital Light Labs. On the bottom of this lamp holder, a dry air channel is built-in to allow air to blow evenly over the sample surface, and the gas flow rate can be controlled on a rotameter. The LED lamp is manually triggered by an ultraviolet illumination and measurement system. The LED light exposure can be programmed through AccuCure software. For measurement, place 25 μl of the liquid sample at the center of the ATR crystal. Prepare a 3 mil film using a customized coating applicator (3 mil WFM, G1046 from BYK). Place the LED lamp with the holder on top of the ART platform. Then start the FTIR scan to first collect the liquid IR spectrum. Collect each IR spectrum at a specific exposure time under 10 mW / cm 2 of the LED light. Measure the acrylate conversion at the peak height under the reference peak near 1727 cm -1 ; also measure the acrylate peak of SR 8 33S at about 1407 cm -1 , the epoxide peak of UviCure S105 at about 790 cm -1 and the peak of UviCure S130 at about 970 cm -1The oxetane peak at [location]. Since the ring-opening of both the epoxide and oxetane generates the C-O-C bond, the growth of the C-O-C IR peak height at ~1100 cm -1 is also monitored. The growth rate of the peak at 1100 cm -1 can be calculated to evaluate the total cationic curing rate. The peak height is determined using the same baseline, where the baseline is selected as the two lowest points between 600 cm -1 and 1800 cm -1 . Then the peak height below the peak and above the baseline is measured. The integration limits for the liquid and cured samples are not the same but are similar, especially for the reference peak.

[0594] The ratios of the acrylate peak height, epoxide peak height, ring-opening peak height of the epoxide and oxetane to the reference peak height for the liquid and cured samples are determined. The degree of cure or conversion or peak growth rate, expressed as the percentage of the acrylate or epoxide or ring-opening of both the epoxide and oxetane that has reacted, is calculated by the following equation:

[0595]

[0596]

[0597] where R liq is the peak height ratio of the liquid sample, and R c is the peak height ratio of the LED-cured sample. The resulting acrylate and epoxide conversions or C-O-C growth rates are collected and listed in Tables 13 to 21 and plotted in Figures 1 to 8 and Figure 10 .

[0598] UV-Visible Spectroscopy Measurement

[0599] Using a Shimadzu UV1800 spectrophotometer, according to ASTM E169-04, a quartz cell with a 1.0 cm path length cuvette is used, and the UV-Vis spectrum of each sample is obtained by scanning the spectrum in the wavelength range of 450 to 200 nm. The measuring cell is filled with an acetonitrile solution of 10 ppm photoinitiator to ensure that the absorbance observed within the spectral range of the desired absorbance value does not exceed 1.0.

[0600] Working Curve Measurement

[0601] At 405 nm ~ 3 mW / cm from B9Creation 2 Flashforge Hunter DLP printer or 405 nm ~ 12 mW / cm 2Print the working curve on a B9 Core 550 DLP printer. Irradiate various energy doses in the section of the build area (without the build platform installed), causing individual squares or films to be cured. Measure the thickness of each film using a low-force digital caliper + comparator stand from Mitutoyo to determine the cure depth. Use the curve of cure depth versus the logarithm of the energy dose to determine the critical exposure (Ec, mJ / cm 2 ) and the penetration depth (Dp, mils).

[0602] Fabrication of Tensile Test Specimens

[0603] Print the diagnostic part on a 405 nm B9 Core 550 DLP 3D printer at an irradiance of approximately 12 mW / cm 2 . Design a Type IV tensile dogbone according to ASTM D638-14 in CAD software and export it to an STL file to allow 3D printing of the diagnostic part. The part is printed directly on the build platform without support structures in the XY plane at a layer thickness of 50 microns. The energy dose used for each 50-micron layer printed is 50 mJ / cm for Example 17 2 and 25 mJ / cm for Example 18 2 . These energy doses are determined from the working curve data that allows a cure depth of 150 microns. Make minor adjustments based on iterative experiments to maximize printability and resolution.

[0604] Post-cure the part for 20 minutes on each side in a Sprintray ProCure UV post-curing device. The irradiance measurements of the post-curing unit at various wavelengths are shown below, which are collected using an Ophir Starbright power meter coupled with a PD300RM-UV radiometer.

[0605] [Table 22]

[0606] Table 22: Irradiance measurements of the post-curing unit at various wavelengths

[0607] After UV post-curing, condition the samples for seven days before testing according to ASTM D618-13 - Procedure A.

[0608] Mechanical Testing of 3D Printed Articles:

[0609] Test the samples using an Instron 5966 universal testing device equipped with 5 kN wedge grips according to ASTM D638-14. Use a draw rate of 5 mm / min, and use a static axial clip-on extensometer to determine the Young's modulus.

[0610] 4.3 Results and Discussion

[0611] 4.3.1. Curing Performance in Hybrid Systems

[0612] As listed in Table 13, acrylate and epoxide show at 405 nm in the following Figure 1 and Figure 2 in.

[0613] The results show that in the high-epoxide (HE) or low-epoxide (LE) of the hybrid system: 1) All novel cationic photoinitiators show better acrylate curing than Omnicat 550; 2) All novel cationic photoinitiators show better epoxide and total cation curing than Speedcure 992. The epoxide curing of photoinitiators 5, 1, and 4 is also better than that of Omnicat 550, which matches the control sample SC938 / CPTX.

[0614] As listed in Tables 13 to 18, the effects of different radical photoinitiators or no radical photoinitiator on the curing of acrylate, epoxide, and total cation at 405 nm are shown in the following Figure 3 , 4 and 5.

[0615] The results show that in the high-epoxide (HE) or low-epoxide (LE) of the hybrid system: 1) Both 5 and 4 show high acrylate curing with or without a radical photoinitiator. In the presence of the short-wavelength radical initiator BKL or XKm with low 405 nm absorption, even without any radical photoinitiator, both 4 and CPTX-CPT can cure acrylate as well as SC938 / CPTX. 2) Both 5 and 4 show better epoxide curing and total cation curing than Omnicat 550 and SC992 with or without a radical photoinitiator. Generally, both 5 and 4 perform well in the hybrid system and match SC938 / CPTX.

[0616] At the short wavelength (e.g., 365 nm) of LED exposure, the performance of those novel cationic photoinitiators is similar to that of SC938 / CPTX, Omnicat 550, and SC992, as listed in Tables 13 to 18.

[0617] 4.3.2. Curing Performance in Cationic Systems

[0618] As listed in Tables 19 to 21, the curing of epoxide, oxetane, and total cation at 405 nm is shown in the following Figure 6 , Figure 7 and Figure 8 in.

[0619] Results shown in the cationic system: 1) All four novel cationic photoinitiators 2, 4, 1, and 5 showed better epoxide curing, oxetane curing, and total cationic curing than Omnicat 550 and SC 992. Among them, 5 and 1 performed slightly better than 2 or 4. Neither the radical photoinitiators BKL and TPO-L could promote cationic photopolymerization. In fact, the radical photoinitiators slowed down the cationic curing, and TPO-L slowed it down the most.

[0620] At short wavelengths of LED exposure, such as 365 nm, those novel cationic photoinitiators were very similar to Omnicat 550 and SC938 / CPTX, and slightly better than SC992, as listed in Tables 19 to 21.

[0621] 4.3.3 3D Printability in Hybrid Systems

[0622] UV spectra: As Figure 9 shown, the UV spectra of the four novel sulfonium salts were compared with Omnicat 550, Speedcure 992S (>99% active ingredient), and Speedcure 938. At 405 nm, the UV absorption decreased in the order of 5 > 1 > 2 ≈ 4, and they were all much higher than Omnicat 550 and SC 992S. SC938 had no absorption at all at the wavelength of 310 nm.

[0623] Formulations for 3D printing at 405 nm: Typical hybrid systems were selected to evaluate the printability of both 5 and 4 compared with Omnicat 550 and SC992, as shown in Table 23. Working curve data were measured from a 3.1 mW and 405 nm Flashforge Hunter DLP printer or a ~10 mW and 405 nm B9 Core 550 DLP printer

[0624] [Table 23]

[0625] Table 23: Formulations for 405 nm DLP printers and their properties from printed parts

[0626] Working curve square films of each formulation were printed by a 3.1 mW and 405 nm Flashforge Hunter DLP printer or a ~10 mW and 405 nm B9 Core550 DLP printer and are listed in Table 23 along with the printing exposure conditions. As expected, neither SC992 (Ctr 10) nor Omnicat 550 (Ctr 11) was printable even at excessive exposure times. The two new sulfonium salts were well printed and generally lower concentrations of 5 could provide lower Dp and higher Ec than 4 due to its high absorption at Figure 9 405 nm.

[0627] In dry air at a flow rate of 10 LPM, both acrylate and epoxide curing of formulations Ex 17 and Ex 18 could be well cured under a 10 mW 405 nm LED as Figure 10 shown.

[0628] By using a ~10 mW and 405 nm B9 Core 550 DLP printer, a set of tensile parts were successfully printed from formulations Ex 17 and Ex 18 and the post-UV cured parts provided a set of desired tensile property data as listed in Table 23.

Claims

1. A compound of formula (I): (I)， Wherein: - n is 1 or 2, - Y is an anion with a valence of y, - When n is 2, X is selected from a single bond, S, and O, When n is 1, X is R 11 , - Ar is an optionally substituted aromatic ring selected from benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, and phenyl, Provided that: - When Ar is selected from benzofuranyl, dibenzofuranyl, benzothiophenyl, and dibenzothiophenyl, n is 1, - When Ar is phenyl and n is 1, the -Ar-X group has the following formula: ， Wherein: -R 12 and R 13 are connected to each other such that the -Ar-X group represents , Wherein: -R 16 , R 17 , R 18 and R 19 are independently selected from H, halogen, (C1-C6) straight-chain or branched-chain alkyl, (C1-C6) straight-chain or branched-chain alkoxy, -O-(CH2) i -COOR 28 or -(CH2) i -CH-(COOR 28 )2 groups, where i is 1 or 2, and R 28 is H or (C1-C4) straight-chain or branched-chain alkyl, and -R 11 、R 14 、R 15 independently is H, halogen, (C1-C6) straight-chain or branched alkyl, (C1-C6) straight-chain or branched alkoxy, and -S-Ph-C(=O)-Ph, - or R 12 and R 13 are not connected to each other, and R 11 、R 12 、R 13 、R 14 and R 15 are independently selected from H, halogen, (C1-C6) linear or branched alkyl, (C1-C6) linear or branched alkoxy, pyrrolidin-1-yl, -L-Ph 1 group, where L is a single bond, CH2 or O, and Ph 1 is a phenyl optionally substituted with one or more substituents selected from halogen, (C1-C6) linear or branched alkyl, and (C1-C6) linear or branched alkoxy, The condition is R 11 , R 12 and R 13 in which at least one group is selected from halogen, (C1-C6) linear or branched alkoxy, pyrrolidin-1-yl, -L-Ph 1 group, where L is a single bond, CH2 or O, and Ph 1 is a phenyl optionally substituted with one or more substituents selected from halogen, (C1-C6) linear or branched alkyl, and (C1-C6) linear or branched alkoxy, - When Ar is phenyl and n is 2, the -Ar-X-Ar- group has the following formula: or , wherein R 20 , R 21 , R 22 , R 23 , R 24 , R 25 , R 26 and R 27 are independently selected from H, (C1-C6) linear or branched alkyl, (C1-C6) linear or branched alkoxy, and -O-(CH2) j -COOR 29 or -(CH2) j -CH-(COOR 29 )2 groups, where j is 1 or 2, and R 29 is H or (C1-C4) linear or branched alkyl, -R 1 and R 6 are independently selected from H, halogen, (C1-C6) straight or branched chain alkyl, (C1-C6) straight or branched chain alkoxy, and -O-(CH2) k -COOR 30 or -(CH2) k -CH-(COOR 30 )2 groups, where k is 1 or 2 and R 30 is H or (C1-C4) straight or branched chain alkyl, -Ph 2 is a phenyl group optionally substituted by one or more substituents selected from halogen, (C1-C6) linear or branched alkyl, and (C1-C6) linear or branched alkoxy, -R 2 、R 4 、R 5 、R 7 、R 8 、R 9 and R 10 are independently selected from H, halogen, (C1-C6) straight-chain or branched alkyl, (C1-C6) straight-chain or branched alkoxy, and -O-(CH2) m -COOR 32 or -(CH2) m -CH-(COOR 32 )2 groups, where m is 1 or 2, and R 32 is H or (C1-C4) straight-chain or branched alkyl.

2. The compound according to claim 1, wherein: - n is 1, and -X is R 11 and - R 12 and R 13 are connected to each other such that the group represents , such that the compound has formula (III): (III), wherein R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 8 、R 9 、R 10 、R 11 、R 14 、R 15 、R 16 、R 17 、R 18 、R 19 、Ph 2 、Y and y are as defined in claim 1.

3. The compound according to claim 2, which has formula (2), (3), (4), (41), (42), or (43), preferably formula (2) or (4): (2), (3), (4), (41), (42), (43), Where Y and y are as defined in claim 1.

4. The compound according to claim 1, wherein: - n is 1, -X is R 11 and -- The -Ar-X group has the following formula: ， wherein R 12 and R 13 are not connected to each other, such that the compound has formula (VI): (VI), wherein R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 8 、R 9 、R 10 、R 11 、R 12 、R 13 、R 14 、R 15 、Ph 2 、Y and y are as defined in claim 1.

5. The compound according to claim 4, having formula (7), (9), (11), (18), (25), or (27), preferably having formula (25) or (27): (7), (9), (11), (18), (25), (27), Where Y and y are as defined in claim 1.

6. The compound according to claim 1, wherein: - Ar is phenyl, and - n is 2, -- The -Ar-X-Ar- group has the following formula: ， such that the compound has formula (X): (X)， wherein R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 8 、R 9 、R 10 、R 20 、R 21 、R 22 、R 23 、Ph 2 、X, Y and y are as defined in claim 1.

7. The compound according to claim 6, having formula (29): (29), Where Y and y are as defined in claim 1.

8. The compound according to claim 1, wherein: - n is 1, and - Ar is selected from benzofuranyl, dibenzofuranyl, benzothiophenyl, and dibenzothiophenyl, such that the compound has formula (XIV): (XIV), Wherein: -R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 6 、R 8 、R 9 、R 10 、R 11 、Ph 2 、Y and y are as defined in claim 1, and - Ar is selected from benzofuranyl, dibenzofuranyl, benzothiophenyl, and dibenzothiophenyl.

9. The compound according to claim 8, having formula (10), (19), (20), or (21): (19), (20), (10), (21), Where Y and y are as defined in claim 1.

10. The compound according to any one of claims 1 to 9, wherein the anion Y y- is selected from halide ions, HSO4 - , SO4 2- , ClO4 - , BF4 - , PF6 - , AsF6 - , SbF6 - , SbF5(OH) - , SbF4(OH)2 - , BPh4 - , B(C6F5)4 - , Al[OC(CF3)3]4 - , CH3COO - , CH3SO3 - , CH3C6H4SO3 - , CF3COO - , CF3SO3 - , N(CF3SO3)2 - , or B[C6H3(CF3)2]4 - , and is preferably selected from PF6 - , SbF6 - , and B(C6F5)4 - .

11. A method for preparing a compound of formula (I) as defined in claim 1, comprising the following steps: b) Reacting a compound of formula (XXI): (XXI), wherein R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 8 、R 9 、R 10 and Ph 2 are as defined in claim 1, - with a compound of formula (XXII): H-Ar-R 11 (XXII), Wherein: -R 11 as defined in claim 1, and - Ar is an optionally substituted aromatic ring selected from benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, and a phenyl of the following formula: ， wherein R 11 、R 12 、R 13 、R 14 and R 15 are as defined in claim 1, to form a compound of formula (I) wherein n is 1 and X is R 11 , - or reacting with a compound of formula (XXV): (XXV), Where -R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 8 、R 9 、R 10 and Ph 2 as defined in claim 1, -- The -Ar-X-Ar-H group has the following formula: or , Wherein: -R 20 、R 21 、R 22 、R 23 、R 24 、R 25 、R 26 and R 27 as defined in claim 1 - X is selected from a single bond, S, and O, to form a compound of formula (I), wherein n is 2 and X is selected from a single bond, S, and O, in the presence of an activator, thereby obtaining a compound of formula (I) as defined in claim 1, c) When a compound of formula (I) in which Y y- is different from the Y obtained in step b y- is required, an ion exchange reaction is carried out with a salt containing Y' y- as the anion or an acid having Y' y- as the base to obtain a compound of formula (I) as defined in claim 1 below: wherein Y' y- has the same definition as Y as defined above y- but is different from the Y obtained in step b y- .

12. A photoinitiator composition comprising a mixture of compounds of formula (I) according to any one of claims 1 to 10.

13. A curable composition comprising: - a compound of formula (I) according to any one of claims 1 to 10 or a photoinitiator composition according to claim 12; and - a cationically polymerizable compound.

14. The curable composition according to claim 13, wherein, based on the total weight of the curable composition, the curable composition comprises from 0.05% to 10% by weight, in particular from 0.1% to 5% by weight, more particularly from 0.5% to 2% by weight of the compound of formula (I).

15. The curable composition according to claim 13 or 14, wherein the cationically polymerizable compound comprises at least one compound selected from the group consisting of epoxides, oxetanes, oxolanes, cyclic acetals, cyclic lactones, thiiranes, thietanes, spiroorthoesters, vinyl ethers and mixtures thereof, preferably alicyclic epoxides and optionally oxetanes.

16. The curable composition according to any one of claims 13 to 15, wherein the curable composition further comprises a free-radically polymerizable compound, the free-radically polymerizable compound comprising at least one ethylenically unsaturated compound, preferably a (meth)acrylate-functionalized compound.

17. The curable composition according to claim 16, wherein, based on the total weight of the curable composition, the curable composition comprises from 5% to 95% by weight, preferably from 8% to 90% by weight, more preferably from 10% to 80% by weight, most preferably from 15% to 75% by weight of the ethylenically unsaturated compound.

18. The curable composition according to any one of claims 13 to 17, wherein the curable composition further comprises a free-radical photoinitiator, preferably the free-radical photoinitiator is selected from the group consisting of benzoin, benzoin ethers, acetophenones, α-hydroxyacetophenones, benzils, benzil ketals, phosphine oxides, acylphosphine oxides, α-hydroxyketones, benzoylacetates, α-aminoketones, benzoylformates, acylgermanium compounds, polymeric derivatives thereof and mixtures thereof, more preferably acetophenones, α-hydroxyacetophenones, phosphine oxides and acylphosphine oxides, even more preferably acetophenones and acylphosphine oxides.

19. The curable composition according to claim 18, wherein, based on the total weight of the curable composition, the curable composition comprises from 0.05% to 10% by weight, in particular from 0.1% to 5% by weight, more particularly from 0.5% to 2% by weight of the free-radical photoinitiator.

20. A method for preparing a cured product, comprising curing the curable composition according to any one of claims 13 to 19, preferably by irradiating the curable composition with at least one light source having a maximum output wavelength in the range of 350 to 460 nm.

21. A 3D printing method, comprising printing a 3D article with the curable composition according to any one of claims 13 to 19, in particular layer by layer or continuously, preferably by irradiating the curable composition with at least one light source having a maximum output wavelength in the range of 350 to 460 nm. Use of a compound as defined in any one of claims 1 to 10, said compound being a photoinitiator, preferably a photoinitiator activatable under irradiation with light at 350 - 460 nm, in particular for the UV curing of formulations comprising monomers which can be polymerized by cationic polymerization, radical polymerization and hybrid cationic / radical polymerization.

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