Fast light curing cyanoacrylate compositions

A light curable adhesive composition comprising:

• 1) a photoinitiator system selected from
• a) a combination of ferrocene compound of formula (I)
• wherein
• R1 is hydrogen or C1-C4 alkyl;
• one or more R1 groups are present in one or both cyclopentadienyl rings, and
• acylgermane compounds selected from compounds of formula (II) or (III):
• wherein
• R2 is methyl or phenyl, and
• R3 is hydrogen or methoxy, and
• b) acylgermane compound of formula (IV)
• wherein
• R2 is as defined above, optionally combined with a radical photoinitiator,
• 2) at least one compound of formula (V)
• wherein
• A is selected from the group consisting of CN, CO2Me and CO2Et, and
• when A is CO2Me, D is CO2Me;
• when A is CO2Et, D is CO2CH2CO2Et;
• when A is CO2Et, D is CO2Et;
• and
• when A is CN, D is a carboxylic ester moiety CO2R4,
• wherein
• R4 is selected from the group consisting of:
• C1-C18 linear or branched alkyl chain, terminally trimethylsilylated C1-C3 alkyl chain, partially fluorinated —CH2CF3, —CH2CF2CF3, —CH2(CF2)2H, —CH2(CF2)4H, —CH(CF3)CH3, allyl, propargyl, cyclohexyl, cyclohexenyl, methylcyclohexyl, methylcyclohexenyl, ethylcyclohexyl, ethylcyclohexenyl, furfuryl, phenylethyl, phenoxyethyl, and an acrylic ester moiety of formula (VI):
• wherein
• T is:
• (CH2)z, wherein the value of z is between 2 and 12 inclusive, or C3-C12 branched alkyl chain, bisphenyl, bisphenol, and R5 is H, Me, CN or CO2R6, wherein R6 is a methyl or ethyl group;
• a group of formula (VII)
• wherein
• R7 is selected from the group consisting of H and Me, R8 is selected from the group consisting of Si(Me3)3, and a C1-C6 linear or branched alkyl chain, and the value of n is between 1 and 3 inclusive, and
• 3) at least one acid stabilizer compound selected from the group of Lewis acids.