Process for producing polycondensation product

A process for producing an oxyalkylene containing polycondensation product by polycondensing monomers including (A) an aromatic or heteroaromatic compound containing a polyoxyalkylene chain, which is represented by formula (I),

• wherein
• D is an unsubstituted or substituted aromatic or heteroaromatic group having from 5 to 10 ring members, optionally phenyl or naphthyl of which each is optionally substituted by one or more substituents selected from the group consisting of OH, —OR3, —NH2, —NHR3, C1-C10-alkyl, —SO3H, —COOH, —PO3H2, and —OPO3H2, where the C1-C10-alkyl are optionally substituted by phenyl or 4-hydroxyphenyl, R3 is a C1-C10-alkyl;
• R1 is a group selected from H, C3-C8-cycloalkyl, C6-C10-aryl and 5 to 10 membered heteroaryl;
• R2 is a group selected from H, C3-C8-cycloalkyl, C6-C10-aryl and 5 to 10 membered heteroaryl;
• X is a group selected from H, C1-C10-alkyl, C3-C8-cycloalkyl, C6-C10-aryl, 5 to 10 membered heteroaryl and C1-C10-alkyl carbonyl;
• E is —O—, —NH—, or —N—;
• n is 1, when E is —O— or —NH—;
• or n is 2, when E is —N—;
• and
• m is an integer from 1 to 300;
• and
• (B) an aromatic or heteroaromatic compound which is different from monomer (A) and is represented by formula (II),
• F is an unsubstituted or substituted aromatic or heteroaromatic group having from 5 to 10 ring members, optionally phenyl or naphthyl of which each is optionally substituted by one or more substituents selected from the group consisting of OH, —OR3, —NH2, —NHR3, —NR32, C1-C10-alkyl, —SO3H, —COOH, —PO3H2 and —OPO3H2, where the C1-C10-alkyl are optionally substituted by phenyl or 4-hydroxyphenyl, R3 is a C1-C4-alkyl;
• R4 is a group selected from H, C1-C10-alkyl, C3-C8-cycloalkyl, C6-C10-aryl and 5 to 10 membered heteroaryl;
• R5 is a group selected from H, C1-C10-alkyl, C3-C8-cycloalkyl, C6-C10-aryl and 5 to 10 membered heteroaryl;
• Y is a group selected from H, C1-C10-alkyl, —COOH, C1-C4-alkyl-COOH, —SO3H, C1-C4-alkyl-SO3H, —PO3H2 and C1-C4-alkyl-PO3H2;
• G is —O—, —NH— or —N—;
• q is 1, when G is —O— or —NH—;
• or q is 2, when G is —N—;
• and
• p is an integer from 0 to 300;
• and
• (C) an aldehyde, in the presence of a protonation catalyst, wherein the aldehyde is provided by a fast-releasing aldehyde source and a slow-releasing aldehyde source, wherein the molar ratio of the aldehyde from the fast-releasing aldehyde source and that from the slow-releasing aldehyde source is in the range of 5:1 to 1:1