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EP-3902878-B1 - PHOTOINITIATORS

EP3902878B1EP 3902878 B1EP3902878 B1EP 3902878B1EP-3902878-B1

Inventors

  • MORONE, Marika
  • NORCINI, GABRIELE
  • CASALUCE, Gianni
  • BERNINI FREDDI, Andrea
  • POSTLE, STEPHEN

Dates

Publication Date
20260506
Application Date
20191220

Claims (11)

  1. A photoinitiator of formula (Ia) and (II): wherein: - n is 1 or 2; - when n is 1, Ar' is selected from one of the following groups: C6-C12 aryl, tetrahydronaphthyl; carbazolyl; and N-alkylcarbazolyl, all said groups being possibly substituted by one or more electrodonating groups selected from OH, C1-C18 alkyl, -Oalkyl, - Oalkoxy, - Ophenyl, -SH, -Salkyl, -Salkoxy, -Sphenyl, -SO2alkyl, -SO2alkoxy, - SO2phenyl, -COOalkyl, SO2NH2, -SO2NHalkyl, -SO2N(alkyl)2, - NHalkyl, -NHalkoxy, - N(alkyl)2, morfolino, piperidino, piperazino, - N(alkoxy)2, -NHCOalkyl or -NHCOphenyl; provided that when C6-C12 aryl is a phenyl group then said phenyl group is always substituted by one or more electrodonating groups as above defined; - when n is 2, Ar' is selected from an -arylene-T-arylene- group such as a -phenylene-T-phenylene- group and a trimethyl-phenyl-indane group such as the one of formula - Y is selected from a direct bond, -CH 2 - and -CH 2 -CH 2 -; - Z is -CH 2 ; - T is selected from a direct bond, -O-, -S-, and -CH 2 -,; - R 1 is C1-C8 alkyl; - R 2 is selected from R 1 ; or R 1 nd R 2 , together with the carbon atom to which they are bound, represent C5-C12cycloalkyl; - R 3 , R 4 , R 5 , R 6 and R 7 , each independently, are selected from C1-C8alkyl; - R 8 and R 9 , each indipendetly, are selected from C1-C18alkyl which is unsubstituted or substituted by -OH, -Oalkyl, or -CN; - R 10 is selected from -CONH 2 , -CONHalkyl, -CON(alkyl) 2 and - P(O)(Oalkyl) 2 ; - R 11 is selected from hydrogen, -OH, C1-C18 alkyl, -Oalkyl, -SH and -Salkyl; - R 12 has one of the meanings assigned to R 11 ; and wherein: - when R 1 and R 2 , together with the carbon atom to which they are bound represent C5-C12cycloalkyl, then Ar' can also be unsubsituted.
  2. The photoinitiator of claim 1 wherein in formula (Ia) Ar' is selected from a substituted phenyl and a group selected from tetrahydronaphthyl, carbazolyl and N-alkylcarbazolyl.
  3. The photoinitiator of claim 1, wherein in formula (Ia) Ar' is selected from a substituted phenyl and C5-C12cycloalkyl is a C6-C10cycloalkyl, more preferably a cyclohexyl group.
  4. The photoinitiator of claim 1 to 3 wherein in formula (Ia) n is 1.
  5. The photoinitiator of any one of claims 1 to 4 wherein formula (Ia) and (II) R 3 , R 4 , R 5 , R 6 , R 7 are, each independently one to one other, methyl or ethyl.
  6. The photoinitiator of any one of claims 1 to 5 wherein in formula (II) R 11 and R 12 are hydrogen.
  7. A phorocurable composition comprising ethylenically unsaturated compounds and a α-disilyloxyketones photoinitiator of formula (I) or (II) wherein: - n is 1 or 2; - when n is 1, Ar is selected from one of the following groups: C6-C12 aryl, tetrahydronaphthyl; carbazolyl; and N-alkylcarbazolyl, all said groups being possibly substituted by one or more electrodonating groups selected from OH, C1-C18 alkyl, -Oalkyl, - Oalkoxy, - Ophenyl, -SH, -Salkyl, -Salkoxy, -Sphenyl, -SO2alkyl, -SO2alkoxy, - SO2phenyl, -COOalkyl, SO2NH2, -SO2NHalkyl, -SO2N(alkyl)2, - NHalkyl, -NHalkoxy, - N(alkyl)2, morfolino, piperidino, piperazino, - N(alkoxy)2, -NHCOalkyl or -NHCOphenyl; - when n is 2, Ar is selected from an -arylene-T-arylene- group such as a -phenylene-T-phenylene- group and a trimethyl-phenyl-indane group such as the one of formula - Y is selected from a direct bond, -CH 2 - and -CH 2 -CH 2 -; - Z is -CH 2 ; - T is selected from a direct bond, -O-, -S- and -CH 2 -; - R 1 is C1-C8 alkyl; - R 2 is selected from R 1 ; or R 1 and R 2 , together with the carbon atom to which they are bound, represent C5-C12cycloalkyl; - R 3 , R 4 , R 5 , R 6 and R 7 , each independently, are selected from C1-C8alkyl; - R 8 and R 9 , each indipendetly, are selected from C1-C18alkyl which is unsubstituted or substituted by -OH, -Oalkyl or -CN; - R 10 is selected from -CONH 2 , -CONHalkyl, -CON(alkyl) 2 and - P(O)(Oalkyl) 2 ; - R 11 is selected from hydrogen, -OH, C1-C18 alkyl, -Oalkyl, SH and Salkyl; - R 12 has one of the meanings assigned to R 11 ; - or R 11 and R 12 , together with the carbon atoms to which they are bound, represent C5-C12cycloalkyl or C6-C12 aryl; and wherein: - when R 1 and R 2 , together with the carbon atom to which they are bound represent C5-C12cycloalkyl, then Ar' can also be unsubsituted.
  8. A process for photocuring photopolymerizable compositions and inks, which process comprises: I) preparing a photopolymerizable composition as defined in claim 7 II) coating or printing said photopolymerizable composition III) photopolymerizing said coated or printed composition with a light source on said substrate.
  9. The process of claim 8, wherein the photopolymerization is carried out with a LED light source emitting a wavelengths comprised between 365 nm to 600 nm.
  10. A method for broadening the spectral working wavelength of α-disilylarylketone photoinitiators of formulas (I), (Ia) or (II) as defined in any one of claims 1 to 7, which comprising adding a sensitizer to said α-disilylarylketones, wherein said sensitizer is selected from the group of aromatic carbonyl compounds having triplet energy of 225-310 kJ/mol.
  11. Use of disilylarylketone of formulas (I), (Ia) or (II) as defined in any one of claims 1 to 7, as photoinitiators.

Description

PRIOR ART AND TECHNICAL BACKGROUND The dynamic growth of UV curing is dependent on continued innovation to support this technology in the overcaming of always new challenges and this is reflected by rapid development of new materials needed for the formulations. In particular one key component is the photoinitiator, its role is that to convert light to chemical energy in the form of reactive intermediates. These intermediates are radicals able to initiate radical polymerization of the double bonds present in the formulation to be cured. The development in the field of photoinitiators are stimulated by various factors. Firstly, there is a continuous improvement of photoinitiators for existing applications such as coatings, inks, adhesives or electronics because there is no single photoinitiator that is able to meet all the requirements of each application, like for instance line speed, surface curing, discoloration after curing or solubility. Secondly, the introduction of new lamps, such as LED lamps, stimulated the development of photoinitiators tuned at that wavelength. Thirdly, the inscreasing number of photoinitiators banned as toxic or reprotoxic. In the last years, various attempts were made to develop new photoinitiators able to mimic standard photoinitiators or to overcome problems such as yellowing, higher line speed, curing under LED lamps, deep curing, some examples are 3-ketocoumarins (US9951034, WO/2017/216699), acylgermanium photoinitiators (EP3150641, EP2649981), benzoyl phenyltelluride PIs (Macromolecules, 2014, 47(16), 5526-5531), silicon based PIs (JP2010229169, Macromolecules, 2009, 42(16), 6031-6037, Macromolecules 2007, 40(24), 8527-8530, Macromol. Rapid Commun. 2017, 38, 1600470, Macromolecules, 2017, 50(17), 6911-6923). In particular, the class of silicon based PIs was widely explored but unfortunately none of known PIs was able to significantly improve at least one of the characteristic cited before. One of the first class of silicon based PIs explored in recent years, was that of the α-disilyloxyketones, which comes from the α-hydroxyketones class but the reactivity compared to that of the parent compound was poorer or comparable and neither the absorption wavelength was positively affected by the disilyloxy substitution. J. Lalevée et al. "Silyl Radical Chemistry and Conventional Photoinitiators: A Route for the Desigh of Efficient Systems"; MACROMOLECULES (2009) and J. Lalevée et al. "Radical photopolymerization reactions under air upon lamp and diode laser exposure: The Chemisty" PROGRESS IN ORGANIC COATINGS (2011) disclose some bi-silylated photoinitiators, referred to as PI-1 and PI-3, but do not mention a photo-crosslinkable composition. AIMS OF THE INVENTION It is a first aim of the invention to provide for novel photocurable compositions comprising α-disilyloxyketones which are higher performing with respect to known α-disilyloxyarylketones containing compositions. It is a further aim of the invention to provide for novel α-disilyloxyarylketones, their use as photoinitiators and photocurable compositions comprising them. Is a further aim of the invention to provide for a process for photocuring ethylenically unsaturated compounds as well as articles of manufacture made by said process. SUMMARY OF THE INVENTION Now, we surprisiling found that an electron donating aromatic group conjugated to the α-disilyloxyketone gives rise to new PIs which are highly reactive compared to the α-disilyloxyarylketones described in the prior art (PI-1 Macromolecules, 2009, 42(16), 6031-6037). Indeed, it was unexpectedly found that the substitution by an electrondonating group on the aryl moiety of the α-disilyloxyarylketones, such as diphenylsulfide or p-morpholinophenyl, results in better perfoming photoinitiators, with a reactivity double to the reference compound above (PI-1). Moreover, we have surprisingly found that all the compounds belonging to the α-disilyloxyarylketone class can be sensitized thus improving the spectral working wavelength and allowing all said compounds working at LED wavelengths (e.g. 400 nm) (which effect was not known), while this result cannot be achieved with other PIs such as α-hydroxyketones. Therefore the addition of a sensitizer in a photocurable composition comprising α-disilyloxyarylketone as the PIs, allows to obtain an unexpected technical improvement, as it will be apparent from the following experimental Examples. DESCRIPTION OF THE INVENTION According to one of its aspects, the present invention relates to a photoinitiator of formula (Ia) and (II): wherein: n is 1 or 2;when n is 1, Ar' is selected form one of the following groups: C6-C12 aryl, tetrahydronaphthyl; carbazolyl; and N-alkylcarbazolyl, all said groups being possibly substituted by one or more electrodonating groups selected from OH, C1-C18 alkyl, -Oalkyl, -Oalkoxy, -Ophenyl, -SH, -Salkyl, -Salkoxy, -Sphenyl, -SO2alkyl, -SO2alkoxy, - SO2phenyl, -COOalkyl, SO2NH2, -SO2NHalkyl, -SO2N(alkyl)2,