White crystalline powder, no obvious toxicity; slightly soluble in cold water, soluble in hot water, ethanol, alkali solution; an important azo dye intermediate, mainly used in the synthesis of acid dyes and direct dyes, suitable for the synthesis of dyes for wool and silk dyeing. Hazard Class: General chemicals; skin irritation
Chinese alias：4,4-二氨基-2,2'-二磺酸（PP酸）
English alias：4,4-Diaminostilbene-2,2'-disulfonic acid
Special intermediate for azo dyes; core used in the synthesis of acid dyes and direct dyes, suitable for dyeing protein fibers such as wool and silk, improve the binding force between dye and fiber, ensure dyeing uniformity and color fastness
| No. | Test Item | Index |
| 1 | Appearance | Dark gray to blue-black uniform powder, no caking |
| 2 | Purity (mass fraction)/% | ≥90.0 |
| 3 | pH value | 4.0-6.0 |
| 4 | Moisture (mass fraction)/% | ≤8.0 |
| 5 | Iron content (mass fraction)/% | ≤0.02 |
| 6 | Sulfate (as SO₄²⁻)/% | ≤0.5 |
Address: Block B, Interstellar Center, Yuhua District, Shijiazhuang City, Hebei Province
