Preparation of reactive phthalocyanine dyes

A process for preparing reactive phthalocyanine dyes of the formula I

• where
• Pc is the radical of a metal-free or metal-containing phthalocyanine system which may be substituted by chlorine or phenyl,
• R.sup.1 is hydrogen or C.sub.1 -C.sub.6 -alkyl,
• R.sup.2 and R.sup.3 singly are independently of each other hydrogen, C.sub.1 -C.sub.6 -alkyl, which may be interrupted by 1 or 2 oxygen atoms in ether function, or phenyl, or together are combined with the nitrogen atom joining them together to form a five- or six-membered saturated heterocyclic radical which may contain further hetero atoms,
• L is C.sub.2 -C.sub.4 -alkylene which may be interrupted by an oxygen atom in ether function, naphthylene or a radical of the formula ##STR18## where U is hydrogen, hydroxysulfonylmethyl or hydroxysulfonyl and n is 1 or 2,
• Y is vinyl or a radical of the formula C.sub.2 H.sub.4 --Q, wherein Q is an alkali-detachable group,
• M.sup..cndot. is the equivalent of a cation,
• m is 0 or 1,
• p is from 1 to 3,
• q is from 0 to 3,
• r is from 1 to 3, and
• t is 0 or 1,
• with the proviso that the sum of p, q and r is not more than 4, by reacting a phthalocyaninesulfonyl chloride of the formula II ##STR19## where Pc and M.sup..cndot. are each as defined above, a is from 1 to 4 and b is from 0 to 3, with the proviso that the sum of a and b is not more than 4, or a mixture of phthalocyaninesulfonyl chlorides of the formula II in any order with an amine of the formula III ##STR20## where R.sup.1, L, Y, m and t are each as defined above, and optionally with an amine of the formula IV ##STR21## where R.sup.2 and R.sup.3 are each as defined above, in an aqueous medium in the presence or absence of a nitrogen-containing heterocycle, which comprises, after the reaction has ended, subjecting the reaction mixture to a membrane treatment to separate it into an aqueous retentate comprising the dyes of the formula I in concentrated form and an aqueous permeate comprising the salts, the amine of the formula III and optionally the amine of the formula IV.