Photopolymer formulation for production of holographic media comprising borates with low tg

A photopolymer formulation comprising a component reactive toward isocyanates, a polyisocyanate component, a writing monomer and a photoinitiator containing at least one dye and a coinitiator, wherein the coinitiator comprises at least one substance of the formula (Ia)

• in which
• R1 is an optionally branched C14- to C22-alkyl radical,
• R2 is an optionally branched and/or optionally substituted C8- to C22-alkyl radical, a cyclohexyl or cycloheptyl radical, a C7- to C10-aralkyl radical, or a phenyl radical substituted by nonionic radicals, and
• R3 and R4 are each independently an optionally branched and/or optionally substituted C1- to C8-alkyl radical or
• R1 is an optionally branched C14- to C22-alkyl radical,
• R2 is an optionally branched and/or optionally substituted C8- to C22-alkyl radical or a C7- to C10-aralkyl radical and
• R3 and R4 together form a —(CH2)4—, —(CH2)5— or —(CH2)2—O—(CH2)2— bridge or
• R1 is an optionally branched C14- to C22-alkyl radical,
• R2, R3 and R4 together with the N+ form an imidazole or pyridine ring substituted at least by one radical selected from C1- to C8-alkyl, C1- to C8-alkoxy, C5- to C7-cycloalkyl, benzyl or phenyl
• and in which
• R21 is an optionally substituted C1- to C22-alkyl, C3- to C22-alkenyl, C5- to C7-cycloalkyl or C7- to C13-aralkyl radical, and
• R22 to R24 are each independently a C6- to C10-aryl radical optionally substituted by at least one radical selected from halogen, C1- to C4-alkyl, trifluoromethyl, C1- to C4-alkoxy, trifluoromethoxy, phenyl and phenoxy.

A process for preparing coinitiators comprising a mixture of substances of the formula (Ia) and salts of the formula (II), and optionally containing substances of the formula (Ib) and/or of the formula (IIIa) and/or of the formula (IIIb),

• in which
• R1 is an optionally branched C14- to C22-alkyl radical,
• R2 is an optionally branched and/or optionally substituted C8- to C22-alkyl radical, a cyclohexyl or cycloheptyl radical, a C7- to C10-aralkyl radical, or a phenyl radical substituted by nonionic radicals, and
• R3 and R4 are each independently an optionally branched and/or optionally substituted C1- to C5-alkyl radical or
• R1 is an optionally branched C14- to C22-alkyl radical,
• R2 is an optionally branched and/or optionally substituted C8- to C22-alkyl radical or a C7- to C10-aralkyl radical and
• R3 and R4 together form a —(CH2)4—, —(CH2)5— or —(CH2)2—O—(CH2)2— bridge or
• R1 is an optionally branched C14- to C22-alkyl radical,
• R2, R3 and R4 together with the N+ form an imidazole or pyridine ring substituted at least by one radical selected from C1- to C8-alkyl, C1- to C8-alkoxy, C5- to C7-cycloalkyl, benzyl or phenyl,
• and in which
• R21 is an optionally substituted C1- to C22-alkyl, C3- to C22-alkenyl, C5- to C7-cycloalkyl or C7- to C13-aralkyl radical, and
• R22 to R24 are each independently a C6- to C10-aryl radical optionally substituted by at least one radical selected from halogen, C1- to C4-alkyl, trifluoromethyl, C1- to C4-alkoxy, trifluoromethoxy, phenyl and phenoxy.
• R11 to R14 are each independently C1- to C4-alkyl,
• R25 is a C6- to C10-aryl radical optionally substituted by at least one radical selected from halogen, C1- to C4-alkyl, trifluoromethyl, C1- to C4-alkoxy, trifluoromethoxy, phenyl and phenoxy. and
• An− is an anion having an AClogP in the range of 3-6 and,
• wherein borates of the formula (IIIa) or a mixture of borates of the formulae (IIIa) and (IIIb) are reacted with an ammonium salt of the formula (VI)
• in which
• R1 is an optionally branched C14- to C22-alkyl radical,
• R2 is an optionally branched and/or optionally substituted C8- to C22-alkyl radical, a cyclohexyl or cycloheptyl radical, a C7- to C10-aralkyl radical, or a phenyl radical substituted by nonionic radicals, and
• R3 and R4 are each independently an optionally branched and/or optionally substituted C1- to C5-alkyl radical or
• R1 is an optionally branched C14- to C22-alkyl radical,
• R2 is an optionally branched and/or optionally substituted C8- to C22-alkyl radical or a C7- to C10-aralkyl radical and
• R3 and R4 together form a —(CH2)4—, —(CH2)5— or —(CH2)2—O—(CH2)2— bridge or
• R1 is an optionally branched C14- to C22-alkyl radical,
• R2, R3 and R4 together with the N+ form an imidazole or pyridine ring substituted at least by one radical selected from C1- to C8-alkyl, C1- to C8-alkoxy, C5- to C7-cycloalkyl, benzyl or phenyl,
• and
• X− is an anion, preferably a halide ion,
• in the presence of a salt of the formula (VII)
• M+An− (VII)
• in which
• M+ is a cation, preferably an alkali metal ion or an ammonium ion, and
• An− is an anion having an AClogP in the range of 3-6 and,
• in a biphasic mixture of water and an ester.

A borate of the formula (VIII)

• in which
• R31 is an optionally branched C14- to C22-alkyl radical,
• R32 is a C7- to C10-aralkyl radical,
• R33 and R34 are each independently an optionally branched and/or optionally substituted C1- to C5-alkyl radical,
• R41 is a C2- to C22-alkyl, C3- to C22-alkenyl, C5- to C7-cycloalkyl or C7- to C13-aralkyl radical and
• R42 to R44 are each independently a C6- to C10-aryl radical substituted by at least one radical selected from halogen, C1- to C4-alkyl, trifluoromethyl, C1- to C4-alkoxy, trifluoromethoxy, phenyl and phenoxy,
• excluding the combination of R31=tetradecyl, R32=benzyl, R33 and R34=methyl, R41=butyl and R42 to R44=phenyl,
• or in which
• R31 is an optionally branched C14- to C22-alkyl radical,
• R32 is a C7- to C10-aralkyl radical,
• R33 and R34 are each independently an optionally branched and/or optionally substituted C1- to C5-alkyl radical,
• R41 is a C2- to C22-alkyl, C3- to C22-alkenyl, C5- to C7-cycloalkyl or C7- to C13-aralkyl radical and
• R42 to R44 are each independently a C6- to C10-aryl radical substituted by at least one radical selected from halogen, C1- to C4-alkyl, trifluoromethyl, C1- to C4-alkoxy, trifluoromethoxy, phenyl and phenoxy,
• or in which
• R31 is an optionally branched C14- to C22-alkyl radical,
• R32 is an optionally branched C8- to C22-alkyl radical or a C7- to C10-aralkyl radical,
• R33 and R34 together form a —(CH2)4—, —(CH2)5— or —(CH2)2—O—(CH2)2— bridge,
• R41 is a C2- to C22-alkyl, C3- to C22-alkenyl, C5- to C7-cycloalkyl or C7- to C13-aralkyl radical and
• R42 to R44 are each independently a C6- to C10-aryl radical substituted by at least one radical selected from halogen, C1- to C4-alkyl, trifluoromethyl, C1- to C4-alkoxy, trifluoromethoxy, phenyl and phenoxy,
• or in which
• R31 is an optionally branched C14- to C22-alkyl radical,
• R32 is a phenyl radical substituted by one to three radicals from the group of optionally branched C3- to C8-alkyl radical, optionally branched C3- to C8-alkoxy radical, trifluoromethyl, trifluoromethoxy, cyclopentyl, cyclohexyl, cycloheptyl, phenyl and phenoxy,
• R33 and R34 are each independently an optionally branched and/or optionally substituted C1- to C5-alkyl radical,
• R41 is a C2- to C22-alkyl, C3- to C22-alkenyl, C5- to C7-cycloalkyl or C7- to C13-aralkyl radical and
• R42 to R44 are each independently a C6- to C10-aryl radical substituted by at least one radical selected from halogen, C1- to C4-alkyl, trifluoromethyl, C1- to C4-alkoxy, trifluoromethoxy, phenyl and phenoxy,
• or in which
• R31 is an optionally branched C14- to C22-alkyl radical and
• R32, R33 and R34 together with the N+ atom form an imidazole or pyridine ring substituted at least by one radical selected from C1- to C8-alkyl, C1- to C8-alkoxy, C5- to C7-cycloalkyl, benzyl or phenyl,
• R41 is a C2- to C22-alkyl, C3- to C22-alkenyl, C5- to C7-cycloalkyl or C7- to C13-aralkyl radical and
• R42 to R44 are each independently a C6- to C10-aryl radical substituted by at least one radical selected from halogen, C1- to C4-alkyl, trifluoromethyl, C1- to C4-alkoxy, trifluoromethoxy, phenyl and phenoxy.