Acid Dye Acid Red GR Acid Red 73
Product Characteristics
Acid Red GR is a water-soluble anionic disazo acid dye.
Basic Physicochemical Properties
1.Water Solubility: Solubility at room temperature is approximately 90–110 g/L; dissolves more rapidly in hot water, forming a red aqueous solution. Acid Red GR is suitable for preparing masterbatch solutions in aqueous systems.
2.Organic Solvents: Acid Red 73 is soluble in ethanol and cuprammonium liquor; slightly soluble in acetone; insoluble in benzene, esters, and most other organic solvents.
3.Reaction with Concentrated Sulfuric Acid: The solution turns red-purple; upon dilution with water, a reddish-brown precipitate forms.
4.Reaction with Concentrated Nitric Acid: Initially shows blue color, gradually turning olive-green, then transitioning to orange.
5.Reaction with Concentrated Hydrochloric Acid: When concentrated HCl is added to the aqueous solution, a dark reddish-brown precipitate forms.
6.Reaction with Sodium Hydroxide: Gradual addition of caustic soda to Acid Red 73 produces a deep brown precipitate.
Water Quality Note: Soft water is recommended. In hard water, calcium and magnesium ions may cause dye flocculation and color spots, affecting dyeing uniformity.
Dyeing Performance and Fastness Parameters (on Wool Substrate)
Dyeing Mechanism: As an anionic disazo acid dye, Acid Red GR bonds to wool, silk, and nylon via ionic interactions. It has no affinity for cotton or linen cellulose fibers and cannot directly dye cotton.
Recommended Dyeing Conditions
Optimal pH: 3.0–4.5, using acetic acid–sulfuric acid bath
Dyeing Temperature: 90–98°C
Leveling Grade: Level 4, excellent discharge performance, ideal for discharge printing processes
Standard Fastness Ratings (on wool at standard depth):
Lightfastness: 4–5
Washfastness: 3–4
Perspiration Fastness: 4
Dry Rubbing: 4–4.5; Wet Rubbing: 3–4
Heat Press Fastness: 4–5
Metal Ion Effects (Key Considerations)
Copper ions:darken and deepen the hue
Iron ions: Cause dull, turbid coloration
Prefer stainless steel for dye vats and piping; avoid cast iron and copper equipment.
Textile Dyeing Guidelines
1.Wool Dyeing: Start dyeing at 40°C, use sodium sulfate as a leveling agent, adjust pH with sulfuric acid, slowly raise temperature to 95–98°C, hold for 40–60 minutes, then cool and wash thoroughly. Suitable for worsted fabrics, yarns, and wool tops.
2.Silk Dyeing: Reduce acidity; use acetic acid bath at pH 3.8–4.2, temperature 85–90°C, avoiding strong acids that damage silk fibers.
3.Nylon: Excellent color yield under acidic conditions; Acid Red 73 can be used for direct and discharge printing on nylon fabrics.
5.Printing: Outstanding performance in discharge printing on wool, silk, and nylon fabrics; after steaming and fixation, thorough washing is required to remove unfixed dye.
Application Areas
1.Textile Dyeing and Printing
Dyeing and discharge printing on wool, cashmere, silk, and nylon; primary shade is yellowish-red, suitable for blending into chestnut red, orange-red, and brown-red series.
2.Industrial Coloring
Leather: Water dyeing of shoe uppers and apparel leathers
Paper: Coloration of specialty paper, decorative paper, and packaging paper
Water-based inks: Fountain pen inks and water-based marker dyes; strict control of water quality and metal ions required to prevent precipitation
Incense, crafts, and water-based color pastes; heavy metal salts can be used to prepare organic lake pigments
3.Other Applications
Coloring of aluminum foil, cement, and wood; small amounts of Acid Red 73 used in biological staining.
Advantages and Disadvantages
Product Advantages
1.Bright and vivid color, typical yellowish-red hue; complementary to Acid Red GR and Acid Red G (bluish-red); excellent discharge performance, suitable for printing processes.
2.Acid Red GR has good water solubility, making mother liquor preparation convenient; strong color compatibility and excellent stability in blending.
3.Moderate leveling, rich color uptake, good overall fastness properties, ample supply, and high cost-effectiveness.
Disadvantages
1.Acid Red 73 is sensitive to copper and iron ions, requiring high standards for water quality and equipment materials.
2.It precipitates and changes color under strong alkaline conditions, making it unsuitable for high pH formulations.
3.Wet rubbing fastness is moderate; post-treatment for color fixation is necessary for dark-colored products.
Packaging, Storage & Transportation
Standard package: 25kg woven bag / fibre drum. Store hermetically, keep dry. Do not store together with strong oxidants.
