Polycyclic photoinitiators

A photopolymerizable composition comprising:

• (A) at least one ethylenically unsaturated photopolymerizable compound and
• (B) at least one photoinitiator compound of formula (I):
• wherein
• X is O, S, a direct bond or CR16R17;
• Y is O or S;
• R1, R2, R3, R4, R5, R6, R7 and R8 independently of each other are hydrogen, halogen, C1-C4alkyl, C5-C7cycloalkyl, phenyl, C1-C4alkoxy, C5-C7cycloalkoxy, phenoxy, C1-C4alkylthio, C5-C7cycloalkylthio, phenylthio, di(C1-C4alkyl)amino, di(C5-C7cycloalkyl)amino, N-morpholinyl, N-piperidinyl or a group of formula (II) or (III):
• provided that
• one of R1, R2, R3 or R4 is a group of formula (II) or (III) and one of R5, R6, R7 or R8 is a group of formula (II) or (III);
• R9 and R10 independently of each other are C1-C4alkyl or together with the C atom to which they are attached form a 5-membered, 6-membered or 7-membered carbocyclic ring;
• R11 is hydrogen, C1-C4alkyl, C5-C7cycloalkyl, 2-tetrahydropyranyl or Si(C1-C4alkyl)3;
• R12 and R13 independently of each other are C1-C4alkyl, C2-C12alkenyl, phenyl-C1-C4alkyl, phenyl-C1-C4alkyl which is substituted by C1-C4alkyl, or R12 and R13 together with the C atom to which they are attached form a 5-membered, 6-membered or 7-membered carbocyclic ring;
• R14 and R15 independently of each other are C1-C4alkyl, C5-C7cycloalkyl, or together with the N atom to which they are attached form a 5-membered, 6-membered or 7-membered ring, which may contain additional heteroatoms O, S or N;
• R16 and R17 independently of each other are hydrogen, C1-C8alkyl, C5-C7cycloalkyl, phenyl-C1-C4alkyl, phenyl or together with the C atom to which they are attached form a 5-membered, 6-membered or 7-membered ring;
• provided that;
• (1) compounds wherein R2 is a group of formula (III) and R14 and R15 together with the N atom to which they are attached form a 6-membered ring, which contains an additional heteroatom O, X is a direct bond and Y is O;
• and
• (2) compounds wherein R2 is a group of formula (III) and R14 and R15 together with the N atom to which they are attached form a 6-membered ring, which contains an additional heteroatom O and X and Y are S;
• and
• (3) compounds wherein R7 is a group of formula (III) and R14 and R15 together with the N atom to which they are attached form a 6-membered ring, which contains an additional heteroatom O and X and Y are S;
• are excluded.