Common Trichromatic Reactive Dye: 3BS Red

Introduction Reactive Red 3BS (C.I. Reactive Red 195) is a commonly used trichromatic color in reactive dyes. Reactive 3RS Yellow (C.I. Reactive Yellow 145) and 2GLN Blue (C.I. Reactive Blue 194) are often combined as a trichromatic set. For medium to deep shades, it can also be paired with 3RS Yellow (C.I. Reactive Yellow 145) and Navy Blue B (C.I. Reactive Black 5).

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1. Basic Information Commercial Names: Reactive Red 3BS, Reactive Red M-3BE, Reactive Red M-3BF, Reactive Red SP-3B, Reactive Brilliant Red ME-3BS, etc. Molecular Formula: C31H19ClN7Na5O19S6 Molecular Weight: 1136.32 CAS Number: 93050-79-4 Structural Formula: Reactive Red 3BS has two isomers: typically referring to the meta-ester C.I. Reactive Red 195, while the other is the para-ester C.I. Reactive Red 241.

2. C.I. Reactive Red 195 vs. C.I. Reactive Red 241

3. Basic Application Properties??????

(1) Solubility:????????

Due to the presence of four SO3Na water-soluble groups on the dye molecule, Reactive Red 3BS exhibits excellent solubility, exceeding 100 g/L at 50°C. During application, color spots rarely occur.

(2). Reactivity:??????

Reactive Red 3BS contains two reactive groups: monochlorotriazine and vinyl sulfone. Since the reactivity of the vinyl sulfone group is significantly higher than that of monochlorotriazine, under normal dyeing conditions, approximately 80% of the reactive groups in C.I. Reactive Red 195 that bond with cellulose fibers are vinyl sulfone, while 20% are monochlorotriazine. The bond between the dye and cotton fiber exhibits stable acid resistance but relatively weaker alkali resistance. However, for C.I. Reactive Red 241, since the vinyl sulfone group is in the para position, its reactivity is lower, and the difference in reactivity between vinyl sulfone and monochlorotriazine is smaller. Consequently, the acid and alkali resistance of the bond between the dye and cotton fiber is more balanced. Generally, dyes with para-ester structures are less expensive than those with meta-ester structures.

(3) Printing Performance:????

When used for printing, Reactive Red 3BS achieves optimal results with a steaming time of 6 minutes. As a dual-reactive-group dye, the color yield remains stable with steaming times between 5 and 10 minutes, showing no significant variation. Due to the high number of water-soluble groups in the dye structure, unfixed dye is easily washed off, and the staining of white grounds is minimal, indicating good performance in this regard.

(4). Effect of Liquor Ratio on Dyeing Performance

Since Reactive Red 3BS has good solubility but low affinity for cotton fibers, its exhaustion and fixation rates on cotton fibers are significantly influenced by the liquor ratio. A smaller liquor ratio results in a higher exhaustion rate, while a larger liquor ratio leads to a lower exhaustion rate and a correspondingly lower final color yield.

The impact of the liquor ratio on dyeing performance also varies across different types of cellulose fibers. Generally, the influence of the liquor ratio, ranked from greatest to least, is as follows: unm Mercerized cotton > mercerized cotton > regenerated cellulose fibers.

5. Comparison of Color Yield at Different Dyeing Temperatures in Cotton-Nylon One-Bath Dyeing When dyeing cotton and nylon in the same bath, Reactive Red 3BS also colors nylon. As the dyeing temperature increases, the color depth on nylon becomes more pronounced.

6. Fastness Properties Reactive Red 3BS exhibits good fastness to washing and rubbing. Its chlorine fastness is also considered good among reactive dyes, though its light fastness is slightly weaker, particularly failing to meet requirements for very light shades. When the dye concentration is below 0.1%, achieving a light fastness of 3–4 levels is challenging. Therefore, for products requiring high light fastness, consider substituting with reactive dyes that offer superior light fastness. During the dyeing or printing reaction process, since the vinyl sulfone reactive group dominates the reaction, the final product’s fastness to alkaline perspiration is lower than its fastness to acidic perspiration. For very deep shades, there is a risk of failing alkaline perspiration fastness tests, which requires attention. The pH of finished fabrics from dyeing and printing mills is typically controlled to be slightly acidic, and the covalent bond formed between vinyl sulfone and cotton fibers remains stable under weakly acidic conditions. As a result, even after prolonged storage, the color fastness of the fabric does not show a significant decline.

7. Build-Up Property Reactive Red 3BS offers good leveling properties and decent build-up. However, when used in exhaust dyeing at concentrations exceeding 4%, its build-up is not as strong as some other reactive dyes, such as C.I. Reactive Red 264 or C.I. Reactive Red 111.

8. Blending Performance: Due to its excellent leveling properties and vibrant color, Reactive Red 3BS is frequently blended with other dyes in commercial products. For example, Reactive Red RGB is a blend of C.I. Reactive Red 195 and C.I. Reactive Red 198, Reactive Red RML is a blend of C.I. Reactive Red 195 and C.I. Reactive Red 23, and Reactive Deep Red C-B is a blend of C.I. Reactive Red 195 and C.I. Reactive Red 278.