موردو جملة الأصباغ والصبغات

Pigments are insoluble colouring particles dispersed in a medium (ink vehicle, plastic resin, paint binder) — they provide opacity and light fastness, and retain their particle structure. Dyes are soluble colouring substances that chemically bond to or dissolve in the substrate — used in textiles, leather, food, and pharmaceuticals. Key implications: pigments require grinding/dispersion to achieve colour development; dyes require fixation to the substrate for washfastness. In textiles: reactive dyes form covalent bonds with cotton OH groups (wash fastness ISO 4A–5); disperse dyes dissolve into polyester fibre at high temperature (washing fastness 3–4); acid dyes bond to nylon and wool via ionic interaction.

Inorganic pigments: Titanium dioxide (TiO₂, Rutile or Anatase) — world's largest volume pigment, whiteness, opacity; Iron oxide pigments (red, yellow, black, brown — Fe₂O₃, FeOOH) — natural and synthetic grades, excellent light fastness, used in coatings and concrete; Carbon black (tinting strength, conductivity in rubber); Ultramarine blue and violet (silicate-based, heat stable to 400°C). Organic pigments: Phthalocyanine Blue (PB15 — bright cyan, high tinting strength, transparent); Phthalocyanine Green (PG7 — strong green, halogenated); Azo pigments — Hansa Yellows, Diarylide Yellows, Monoazo Reds, Naphthol Reds; Quinacridone pigments (PV19 — violet, PR122 — magenta; high transparency and light fastness); Perylene pigments (high heat stability >300°C, for automotive OEM coatings).

Several azo dyes are restricted under REACH Regulation due to reductive cleavage producing carcinogenic aromatic amines (listed in Annex XVII, Entry 43). Restricted azo dyes: those cleaving to 4-aminoazobenzene, benzidine, 3,3'-dichlorobenzidine, and 21 other listed amines are prohibited in textile/leather articles sold to consumers at concentrations >30 mg/kg. Testing: ISO 14362-1 (aqueous extraction of amines from azo dyes). Chromate pigments (lead chromate, PY34) face restrictions (SVHC) — substitute with organic azo yellows or nickel azo yellow (check SVHC separately). Cadmium pigments face EU marketing restrictions. Buyers targeting EU/US markets should always confirm azo dye testing compliance and SVHC absence declarations.

Textile dye fastness is critical for product quality and certification. ISO 105 series governs colour fastness testing: ISO 105-C06 (washing fastness — scale 1–5, 5 = excellent); ISO 105-E04 (perspiration fastness); ISO 105-B02 (light fastness, xenon arc, scale 1–8); ISO 105-X12 (rubbing/crocking, scale 1–5). OEKO-TEX Standard 100 includes colour fastness minimum requirements (wet rub ≥3, wash ≥4, perspiration ≥3/4 depending on product class). GOTS Annex 6 sets minimum fastness values for organic textile certification. Reactive dyes for cotton typically achieve wash fastness 4–5; disperse dyes for polyester 4–5; acid dyes for nylon 3–4.