| 摘要 |
Compositions comprising as componentsA) at least one bisazo compound selected from the group consisting of the compounds of the general formula Ia and of the general formula Ib where R1 is C1-C8-alkyl, R2 is C2-C8-alkyl, R3 and R3' are each C2-C21-alkyl in which up to four CH2 groups of the carbon chain may be replaced by oxygen in ether function, R4 is hydrogen or is R3 (independently of R3), R4' is hydrogen or is R3' (independently of R3'),B) at least one solvent in which said component A) is soluble, and optionallyC) at least one surface-active substance,are useful as dye penetrants for detecting surface cracks or other defects in workpieces to be tested in this respect. |
