Disazo acid dyes

A compound of the general formula (I)

• wherein
• R1, R2, R9 and R10 are independently selected from the group consisting of:
• unsubstituted unbranched C1-6alkyl, unsubstituted branched C3-6alkyl, substituted unbranched C1-6alkyl, substituted branched C3-6alkyl, aryl, and —(CH2)p-aryl wherein p=1, 2, 3 or 4,
• R3 and R8 is selected from the group consisting of:
• hydrogen, unsubstituted unbranched C1-6alkyl, unsubstituted branched C3-6alkyl, substituted unbranched C1-6alkyl, substituted branched C3-6alkyl, unsubstituted unbranched C1-6alkoxy, unsubstituted branched C3-6alkoxy, substituted unbranched C1-6alkoxy, substituted branched C3-6alkoxy, halogen, —NHCO—(C1-6alkyl) with an unbranched C1-6alkyl group, which is substituted or unsubstituted, —NHCO—(C3-6alkyl) with a branched C3-6alkyl group, which is substituted or unsubstituted, and —NHCONH2,
• BR is a bridge of the formula -A-B-A- wherein
• A is selected from the group consisting of:
• substituted phenyl, substituted naphthyl, unsubstituted phenyl, and unsubstituted naphthyl, and
• B is a bridging sulphon,
• the compound of the formula (I) contains 1, 2 or 3 sulpho groups and wherein there are no anionic groups in the bridging member BR.