Acid Dye Acid Red 3R Acid Red 18
Product Characteristics
Acid Red 3R is a water-soluble anionic acid dye of the monoazo trisulfonate type.
Basic Physicochemical Properties
1.Water Solubility: Acid Red 3R exhibits excellent solubility—120–150 g/L at room temperature and up to 250 g/L in boiling water. It dissolves rapidly in cold water, making it suitable for preparing high-concentration stock solutions.
2.Organic Solvents: Slightly soluble in ethanol and cuprammonium solution; insoluble in acetone, benzene, esters, and most other organic solvents.
3.Reaction with Concentrated Sulfuric Acid: Turns purple-red; when diluted with water, Acid Red 18 changes to red-orange and precipitates.
4.Reaction with Concentrated Nitric Acid: Forms a golden-yellow solution.
5.Reaction with Concentrated Hydrochloric Acid: When concentrated HCl is added to aqueous solution, a red precipitate forms.
6.Reaction with Sodium Hydroxide: Gradual addition of caustic soda turns the solution brownish-brown.
Water Quality Note: Preferably use soft water for preparation. In hard water, calcium and magnesium ions reduce solubility, leading to flocculation and color spots.
Dyeing Performance and Fastness Parameters (Wool Substrate)
Dyeing Mechanism: As an anionic azo dye, it fixes onto wool, silk, and nylon via ionic bonding. Acid Red 3R has no affinity for cotton or linen cellulose fibers and cannot directly dye cotton.
Recommended Dyeing Conditions
Optimal pH: 3.5–5.0, using acetic acid–sulfuric acid bath
Dyeing Temperature: 90–98°C
Leveling Grade: 2–3 (moderate leveling); Acid Red 3R requires leveling agents for even dyeing and offers good discharge performance.
Standard Fastness Ratings (at standard depth)
Lightfastness: 3–4
Washfastness: 3–4
Perspiration Fastness: 3
Dry Rubbing Fastness: 4; Wet Rubbing Fastness: 3
Metal Ion Effects (Key Considerations)
Copper ions: Darken and deepen the hue
Iron ions: Cause grayish turbidity
Use 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, then slowly raise temperature to 95–98°C and hold for 40–50 minutes. Due to moderate leveling, always add an acid leveling agent. Suitable for yarn, roving, and lightweight wool fabrics.
2.Silk Dyeing: Use acetic acid bath at pH 4.0–4.8, temperature 85–90°C; slow heating rate to prevent uneven coloring.
3.Nylon Dyeing: Excellent color yield under acidic conditions; Acid Red 18 can be used for direct printing and discharge printing on nylon.
4.Printing: Acid Red 18 is suitable for discharge printing on wool and silk; after steaming, thorough washing is required to remove unfixed dye.
Application Areas
1.Textile Dyeing and Printing
Used for dyeing and discharge printing on wool, cashmere, silk, and nylon. Acts as a primary yellowish-red shade; Acid Red 3R is ideal for blending orange-red and chestnut-red series.
2.Industrial Coloring
Leather: Water dyeing of shoe uppers and apparel leather
Paper: Coloring of specialty paper, decorative paper, and packaging paper
Water-based Inks: Fountain pen inks and water-based marker dyes; high solubility makes Acid Red 3R suitable for high-concentration ink formulations. Strict control of metal ions and water quality is essential to minimize gelation and precipitation risks.
Incense, crafts, and water-based pigment pastes
Detailed Advantages and Disadvantages
Advantages
1.Acid Red 18 features bright, saturated color with a typical yellowish-red hue. Among three major red shades, it has the best water solubility and dissolves easily in cold water, ideal for high-concentration liquid formulations.
2.Excellent color compatibility; readily available supply and high cost-effectiveness.
3.Superior discharge performance, well-suited for printing processes.
Disadvantages
1.Moderate leveling ability; requires leveling agents during dyeing; deep shades are prone to color irregularities.
2.Medium lightfastness; not recommended for outdoor applications exposed to sunlight.
3.Sensitive to copper and iron ions; strict requirements for water quality and equipment materials.
4.Color change and precipitation occur under strong alkaline conditions.
Packaging, Storage & Transportation
Standard package: 25kg woven bag / fibre drum. Store hermetically, keep dry. Do not store together with strong oxidants.
