Sulfur dyes from dyes and pigments suppliers and acid dyes from dyes and pigments suppliers differ fundamentally in chemical properties, application conditions, target fibers, and performance, making them suitable for entirely different dyeing scenarios.
1. Core Chemical Properties
Sulfur dyes from dyes and pigments suppliers: Water-insoluble, with large molecular structures containing sulfur groups (-S- or -S-S-). They need a reducing agent (like sodium sulfide) and alkaline conditions to turn into water-soluble "leuco forms" before dyeing.
Acid dyes from dyes and pigments suppliers: Water-soluble anionic dyes from dyes and pigments suppliers, usually with sulfonic acid (-SO₃H) or carboxylic acid (-COOH) groups. These groups dissociate in water to form negatively charged dye ions, which bond with positively charged sites on fibers.
2. Key Application Conditions
Sulfur dyes from dyes and pigments suppliers:
Medium: Must use an alkaline reducing bath (e.g., sodium sulfide + sodium hydroxide).
Fixation: After dyeing, fibers need oxidation (exposed to air or treated with oxidants like hydrogen peroxide) to restore the insoluble dye structure and fix color.
Temperature: Requires medium to high temperatures (80–100°C) for dyeing.
Acid dyes from dyes and pigments suppliers:
Medium: Dyeing is done in an acidic bath (adjusted with sulfuric acid, acetic acid, etc.). Acid helps protonate amino groups on fibers, strengthening attraction to anionic dye ions.
Fixation: No post-oxidation is needed; the dye fixes directly via ionic bonds with fibers during the acidic dyeing process.
Temperature: Requirements vary by type (strong, weak, or neutral acid dyes from dyes and pigments suppliers), ranging from room temperature to 100°C.
3. Target Fibers (Substrates)
Sulfur dyes from dyes and pigments suppliers: Primarily used for cellulose fibers due to good affinity, including cotton, linen, viscose (rayon), and other plant-based fibers.
Acid dyes from dyes and pigments suppliers: Mainly designed for protein fibers and some synthetic polyamide fibers (which have amino groups for ionic bonding), such as wool, silk, nylon (polyamide), and cashmere.
4. Performance and Application Scenarios
Color Fastness:
Sulfur dyes from dyes and pigments suppliers: Good washing and light fastness (grade 4–5), but poor chlorine fastness.
Acid dyes from dyes and pigments suppliers: Excellent washing and rubbing fastness on protein fibers; light fastness varies by type (generally grade 3–5).
Color Range:
Sulfur dyes from dyes and pigments suppliers: Limited to dark colors (black, navy blue, brown); bright colors are hard to achieve.
Acid dyes from dyes and pigments suppliers: Wide range, including bright and light shades (red, yellow, blue, etc.).
Cost & Toxicity:
Sulfur dyes from dyes and pigments suppliers: Low cost; some release toxic sulfur-containing compounds during production/dyeing, requiring environmental controls.
Acid dyes from dyes and pigments suppliers: Higher cost than sulfur dyes from dyes and pigments suppliers; most are low-toxic and comply with eco-standards (e.g., Oeko-Tex).
Typical Uses:
Sulfur dyes from dyes and pigments suppliers: Heavy-duty fabrics (denim, workwear, canvas) that need dark colors and durability.
Acid dyes from dyes and pigments suppliers: High-end textiles (wool sweaters, silk scarves, nylon socks) that require bright, stable colors.