A
phthalocyanine dye of formula (I) is provided: wherein: M is a
metal group or is absent; n is 1 or 2; X is selected from —CHR3—, —NR3—, —O— or —S—; R1, R2 and R3 are independently selected from
hydrogen, C1-8
alkyl, C1-8 alkoxy, carboxy, carboxy-C1-8
alkyl, hydroxyl, hydroxy-C1-8
alkyl; or R1 and R2, or R2 and R3 together are joined to form a C4-12
aryl or C3-12 heteroaryl group, optionally substituted with 1, 2, 3 or 4
substituent groups, the or each
substituent group being independently selected from C1-12 alkyl, C1-12 alkoxy, phenyl-C1-8 alkyl, phenyl-C1-8 alkoxy, —(OCH2CH2)dORd, cyano,
halogen, amino, hydroxyl,
thiol, —SRv, —NRuRv, nitro, phenyl, phenoxy, —CO2Rv, —C(O)Rv, —OCORv, —SO2Rv, —OSO2Rv, —NHC(O)Rv, —CONRuRv, —CONRuRv,
sulfonic acid,
sulfonic acid salt and sulfonamide; d is an integer from 2 to 5000; Rd is H, C1-8 alkyl or C(O)C1-8 alkyl and Ru and Rv are independently selected from
hydrogen, C1-12 alkyl, phenyl or phenyl-C1-8 alkyl. Dyes of this type are especially suitable for use in netpage and Hyperlabel™ systems.