Section
| HS Code | 341703 |
| Product Name | Acid Green 27 |
| Color Index Name | C.I. Acid Green 27 |
| Color Index Number | 61580 |
| Cas Registry Number | 6408-57-7 |
| Ec Number | 223-943-5 |
| Molecular Formula | C34H32N2Na2O8S2 |
| Molecular Weight | 706.74 g/mol |
| Chemical Class | Anthraquinone dye |
| Dye Class | Acid dye |
| Ionic Nature | Anionic |
| Color Shade | Green |
| Appearance | Dark green powder or granules |
| Solubility | Soluble in water |
| Main Applications | Dyeing of wool, silk, nylon, leather, and paper |
As an accredited Acid Green 27 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Acid Green 27 is supplied in 25 kg double-lined fiber drums with sealed polyethylene inner bags for safe industrial storage and transport. |
| Container Loading (20′ FCL) | Acid Green 27 is packed and loaded into a 20′ FCL container, properly palletized, secured, and labeled for safe transport. |
| Shipping | Acid Green 27 is generally shipped as a non-hazardous chemical dye. Use sealed, labeled containers, keep dry, and protect from direct sunlight. No UN number or transport class is normally assigned. Follow local regulations and standard spill precautions during handling and transport. |
| Storage | Store Acid Green 27 in a cool, dry, well-ventilated area in tightly closed, clearly labeled containers. Keep away from strong oxidizers and incompatible materials, and protect from moisture, direct sunlight, and dust generation. Use secondary containment and follow the manufacturer’s SDS for specific handling and storage requirements. |
| Shelf Life | When stored sealed, dry, and protected from light, Acid Green 27 typically has a shelf life of about 2–5 years. |
Controlled exhaust uptake on wool top and hank yarn accounts for the main textile volume of C.I. Acid Green 27. In package dyeing machines operating at a liquor ratio of 1:8 to 1:12, the dyestuff is pre-dissolved at 80 °C and strained through a 100-mesh stainless steel filter, because undispersed granules produce specking on merino top. The exhaust bath is buffered with acetic acid–sodium acetate to pH 3.8–5.2; formic acid at 0.5–1.0 mL/L is delayed until the bath reaches 85 °C to avoid unlevel strike on fine wool qualities. A fatty amine ethoxylate leveling agent at 0.5–1.5 g/L is used for medium shades of 1.0–3.0% o.w.f. because Acid Green 27 has limited migration below 85 °C. The temperature is raised at 1.0–1.5 °C/min to 98 °C and held for 45–60 min. After cooling to 70 °C, the goods are overflow-rinsed and soaped with a nonionic detergent at 0.5 g/L for 20 min at 80 °C; omission of this soaping step reduces wet-fastness ratings by at least one grey scale step under ISO 105-C06:2010 C1S.
On wool, shade depth controls lightfastness. At 2.0% o.w.f., Acid Green 27 typically returns a blue wool rating of 5–6 under ISO 105-B02:2014, while 0.5% o.w.f. pale shades fall to 4–5. For machine-washable wool, ammonium sulfate is preferred over acetic acid because the gradual pH drop during the hold phase improves levelness. Terminal products include worsted suiting, wool felt, and upholstery yarn. Compliance for these textiles is normally verified against Oeko-Tex Standard 100 Annex 4 limits for extractable heavy metals and chlorophenols; C.I. Acid Green 27 itself is handled under the dyehouse’s REACH exposure scenario for textile auxiliaries, with dust control at charging stations.
On PA6 filament yarn for sock and seamless knitting, Acid Green 27 exhaustion is governed by the concentration of protonated amino end groups and the ionic strength of the dyebath, not by the total volume of acetic acid dosed. For nylon 6 with amino end group content of 35–50 meq/kg, an addition of 1.0–2.0 g/L ammonium sulfate plus 0.3–0.8 mL/L acetic acid to pH 4.5–5.5 limits initial strike to 30% or less at 60 °C. The bath is then raised at 1.5 °C/min to 95 °C, where dye–fibre bonds become reversible and migration levels the shade over 40 min. On PA66, the same pH window is used but the hold time is extended to 60 min because the lower moisture regain and higher glass transition temperature slow dye diffusion into the fibre. In continuous tufted-carpet dyeing, Acid Green 27 is applied at 0.5–2.0% o.w.f. through a low-volume applicator; fixation takes place in a horizontal steamer at 100 °C for 5–8 min. Shade consistency requires monitoring wet pick-up at 300–350% because excess liquor under the doctor blade causes frostiness on cut-pile tips.
| Processing parameter | PA6 package yarn | PA66 carpet filament |
|---|---|---|
| Amino end group range | 35–50 meq/kg | 30–45 meq/kg |
| Exhaustion pH window | 4.5–5.5 | 4.5–5.5 |
| Top temperature | 95 °C | 95–98 °C |
| Hold time after exhaustion | 40 min | 60 min |
| Wet fastness test | ISO 105-C06:2010 A2S | ISO 105-C06:2010 C1S |
Following exhaust dyeing, residual unfixed dye is cleared with a nonionic wetting agent at 0.5 g/L and 60 °C. For medium and heavy shades, a synthetic tanning agent at 2–3 g/L and pH 3.5 improves water fastness by at least one grey scale step under ISO 105-E01:2013. Acid Green 27 must not be combined with cationic fixing agents in the same bath because co-precipitation at the fibre surface produces crocking failure under ISO 105-X12:2016. Terminal products include dyed nylon 6 socks, automotive floor mats, and tufted bedroom carpet.
Chrome-tanned wet-blue leather is dyed with C.I. Acid Green 27 in stainless steel or wooden drums at a float ratio of 200–300% on shaved weight. The anionic sulfonate group binds to cationic chromium–collagen sites, but penetration is restricted if the wet-blue pH after neutralization remains below 4.0. A standard addition sequence neutralises with 0.5–1.5% sodium formate and 0.3–0.8% sodium bicarbonate to pH 4.5–5.0, then adds Acid Green 27 at 0.5–2.0% on wet-blue weight. Drum rotation of 12–16 rpm and a float temperature of 45–55 °C promote diffusion through the grain and corium. Increasing the drum temperature above 60 °C shifts the dye take-up to the grain layer and produces a thinner surface colour; the quantitative depth loss is formulation-dependent and published data for this specific configuration is limited.
After 30 min of dye circulation, 85% formic acid diluted 1:5 with water is added in two feeds of 0.5% each to lower the float to pH 3.6–3.8 and fix the dye. The leather is rinsed at 35 °C and fatliquored with anionic sulfated oils at 4–8%. If fatliquor is introduced before dye fixation, the anionic fatliquor competes for available cationic sites and the colour yield loss can be detected by reflectance at 620–630 nm. For upholstery leather dyed at 2.0% o.w.e., ISO 11640:2018 dry-rub ratings of 4–5 and wet-rub ratings of 3–4 are achievable after correct acid fixation; over-fixation below pH 3.4 risks grain looseness during staking. Vegetable-tanned leather shows lower uptake because the vegetable tannins occupy cationic sites, so shade matching requires incremental dye additions of 0.5% rather than a single large charge. Terminal products include split suede, full-grain shoe upper leather, and bookbinding leather.
Architectural and decorative aluminium after Type II anodizing is coloured with Acid Green 27 by adsorption into the hexagonal pores of the oxide layer. The oxide film thickness is normally 10–15 µm for interior fittings and 20–25 µm for exterior components; after phosphoric acid widening, the pore diameter is 15–25 nm, which is sufficient for the dissolved acid dye molecule. The dye bath is prepared at 1–5 g/L Acid Green 27 in deionized water, adjusted to pH 5.0–5.5 with sodium acetate and acetic acid, and held at 50–65 °C. Immersion for 5–15 min produces progressive build-up of optical density; beyond 20 min the adsorption rate declines because the pore mouths become saturated. Dyed components are rinsed in cold deionized water for 60–90 s and sealed in 5 g/L nickel acetate at pH 5.5–6.0 and 96–100 °C for 20–30 min. Incomplete sealing leaves the oxide pores open and allows dye migration during UV exposure, which lowers the rating under ISO 2135:2017 relative to a fully sealed control; published data for Acid Green 27 under partial sealing is limited, so exterior use requires end-use validation.
Above 70 °C, the dye bath desorbs Colour Index Acid Green 27 from the pore wall and pastel shades become uneven on large extrusions. The working pH must not fall below 4.0 because the positively charged oxide surface precipitates the anionic dye at the pore entrance, creating a green sludge that cannot be levelled without stripping the oxide layer. Batch-to-batch dye concentration is checked by absorbance at 620–630 nm against a calibration curve prepared from the same dyestuff lot. Terminal products include coloured aluminium nameplates, interior trim profiles, and decorative housings covered by RoHS Recast 2011/65/EU when incorporated into electrical and electronic equipment.
In paper stock dyeing, Acid Green 27 is added to bleached kraft or sulfite pulp at the machine chest, where the anionic dye has poor intrinsic retention on cellulosic fibres. Retention is obtained by dosing aluminium sulfate at 1–3 kg/t dry furnish to reduce stock pH to 4.5–5.5 and generate cationic aluminium species. Dye addition at 0.05–0.3% on oven-dry fibre is made before alum addition to avoid localised precipitation in the stock line. When rosin size is present, the sequence dye–alum–rosin is used because simultaneous addition of rosin and dye causes competition for the same cationic sites and reduces colour yield. A cationic polyacrylamide retention aid at 0.02–0.05 kg/t is added after the fan pump to attach dye–alum flocs to fines; this controls coloured white water and limits shade variation on the papermachine. Machine chest temperature is 20–40 °C, and a dwell time of 15–30 min is sufficient for equilibrium adsorption on bleached kraft.
Terminal products for Acid Green 27 in paper include coloured kraft wrapping, tinted tissue grades, and decorative cardstock. When dyed stock is surface-sized, unreacted dye migrates to the paper surface during drying and can bleed on wet contact. Fastness to wet contact is improved by applying a cationic poly-DADMAC fixative at 0.1–0.3 g/L in the size press or by an alum post-dip at pH 4.0. Shade change after wet contact is evaluated by grey scale assessment under ISO 105-A02:1993; published data for Acid Green 27 in paper is limited, so mill-specific fastness trials are required before production runs.
Water-based stamp-pad inks and fibre-tip pen inks use Acid Green 27 as a soluble anionic colourant where glycol humectants and pH buffers prevent drying-induced crystallisation. The dye is dissolved at 5–12% by weight in a vehicle containing 10–20% glycerine or diethylene glycol, 0.1–0.3% sodium benzoate or a phenoxyethanol-based biocide, and a pH buffer at 7.0–8.5. Stamp-pad inks are compounded at 10–15% dye because the open-cell foam pad requires high tinctorial strength to compensate for low fluid release. Viscosity is adjusted to 50–200 mPa·s at 25 °C with a nonionic thickener or low-viscosity cellulose derivative to prevent strike-through on paper. Acid Green 27 is selected over solvent dye when the stamp housing is styrene-acrylonitrile copolymer, because the high-polarity vehicle avoids the stress cracking produced by ketone or glycol-ether solvent systems in solvent-based inks.
Below pH 6.0, protonation of the sulfonate groups reduces solubility and causes precipitation on the nib or pad surface. The dried ink film on paper remains water-sensitive; water-fastness after drying is evaluated by droplet contact and grey scale assessment under ISO 105-A02:1993. In the United States, marker and stamp-pad inks supplied for art or school use require chronic health labelling under ASTM D4236-89; the final ink formulator retains responsibility for mixture-level classification. Terminal products include coloured stamp pads, quick-dry rollerball ink, and fibre-tip marker ink.
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The product designated C.I. Acid Green 27, Colour Index C.I. 61580, is an anionic anthraquinone dyestuff supplied as a dark green water-soluble sodium salt. Commercial model designations include Acid Green 27 and supplier-specific suffix grades; the suffix system is not harmonized across manufacturers and must be read against the supplier technical data sheet. The chromophore is based on a 1,4-bis(arylamino)anthraquinone structure bearing sulfonate functionality; this substitution pattern determines acid-bath exhaustion, migration, and compatibility with levelling agents. Unlike non-sulfonated solvent-soluble anthraquinone greens, the product requires electrolyte-mediated substantivity in aqueous dyebaths and exhibits pH-dependent uptake on polyamide and protein fibres. Its principal industrial uses are exhaustion dyeing of polyamide 6 and 6.6 fibre, wool and silk, with secondary use in leather and anodized aluminium colouring where anionic dye adsorption is controlled by sealed-layer porosity. The product is differentiated from Acid Green 25 by the presence of 5,8-dihydroxy substitution on the anthraquinone ring, which shifts shade and alters photostability and metal sensitivity in hard-water dyebaths.
Commercial lots are standardized against a supplier master reference by spectrophotometric absorbance at the visible absorption maximum after dissolution in deionized water. Because no single ISO product specification covers Acid Green 27, acceptance criteria are established between dyehouse and supplier and generally include dye strength, insolubles, moisture, and pH of aqueous extract. Test methods are adapted from dyestuff procedures; moisture is often determined by ISO 787-2, pH of a 1 % aqueous extract by ISO 787-9, and tamped bulk density by ISO 787-11. The following table lists representative commercial tolerance bands rather than a universal specification; published data for a formal Acid Green 27 monograph is limited.
| Parameter | Typical commercial tolerance | Test basis |
|---|---|---|
| Appearance | Dark green powder or granules | Visual |
| Dye strength | 95–105 % relative to master | Spectrophotometric |
| Moisture | ≤5.0 % | ISO 787-2 |
| Water-insoluble matter | ≤0.5 % | ISO 787-4 |
| pH of 1 % aqueous extract | 7.0–9.5 | ISO 787-9 |
| Tamped bulk density | 0.35–0.65 g/cm³ | ISO 787-11 |
Dye strength is not an absolute purity measurement but a relative colouristic strength against the master, which is why the acceptable band is wider than analytical purity specifications. Moisture above 5.0 % can alter dispenser gravimetric accuracy and promotes clumping in high-humidity storage; therefore, storage in sealed containers below 60 % relative humidity is required. The spectrophotometric dye strength is calculated as the ratio of absorbance of sample to master at the maximum absorption wavelength after correction for moisture; a strength below 95 % requires re-standardization through addition of diluent or increased dyestuff mass in recipes.
Incoming dyehouse quality control typically includes absorbance ratio measurement at the visible absorption maximum against the supplier master and a visual drawdown on polyamide tricot at 1.0 % owf. The drawdown is prepared with acetic acid at pH 5.0 and sodium sulfate at 10 % owf, then rinsed, dried, and assessed under D65 illumination according to ISO 3668 for visual colour comparison. A deviation beyond half a grey scale step from the master drawdown triggers re-standardization. This procedure is not an official product specification but is used to detect lot-to-lot shifts before bulk production.
For automated dye kitchens handling Acid Green 27 as a non-dusting granular solid, dissolution is conducted in a side tank at 70–80 °C under mechanical agitation for 15–20 min before transfer to the main dyebath. Filtration through 50–100 µm stainless steel mesh is recommended to remove low-solubility agglomerates that otherwise deposit on package-dyeing flow restrictors. Operating experience on package dyeing machines with liquor circulation rates of 30–40 L/kg/min indicates that insufficient dissolution produces pressure-drop excursions across the yarn package and unlevel edges. Because solubility is negatively affected by hard-water cations, chelating agents such as EDTA or polyphosphate are added at 0.5–1.0 g/L when total hardness exceeds 150 mg/L CaCO₃. Published solubility limits for Acid Green 27 in hard water are not standardized; the stated addition is an operational starting point rather than an equilibrium solubility correction.
In package dyeing of polyamide 6.6 yarn on vertical spindle machines, Acid Green 27 exhausts rapidly between 70 °C and 95 °C when pH falls below 5.0. The resulting strike is controlled by a two-step pH buffer: ammonium sulfate at 2–3 % on weight of fibre maintains bath pH between 5.0 and 5.5, and acetic acid is added only after 20–30 min of circulation. Levelling performance is assessed by measuring package-to-package shade variation under D65 illumination using ISO 105-A05 grey scale for colour change; acceptance for plain shade is typically grade 4 or better. Where barrel yarn from different spinnerets is processed in the same batch, residual drawing oil and differential crystallinity produce dye-uptake differences that cannot be fully corrected by extended migration time alone.
Dyehouse records from high-temperature package machines with 120 kg batch capacity show that adding Acid Green 27 as a pre-dissolved stream over 15 min at 50 °C reduces package core-to-edge unlevelness compared with single-shot powder addition. Migration at 95 °C is moderate; therefore, a hold time of 30–45 min after reaching top temperature is used for heavy depths of 2.0–3.0 % owf. Suppliers generally recommend a top temperature of 95–100 °C for polyamide 6.6; published data for high-temperature stability above 110 °C is limited, and high-temperature dyeing is not required for this product. Bath exhaustion is determined by transmission spectrophotometry at the visible absorption maximum; final exhaustion below 90 % indicates pH or electrolyte imbalance.
On wool loose stock and top, Acid Green 27 is applied with acetic acid at 1–2 % owf and sodium sulfate at 5–10 % owf. The bath is set at 40 °C, raised at 1 °C/min to 95–98 °C, and held for 45–60 min. Wet fastness on wool is moderate and requires after-treatment with a cationic fixing agent or formic acid rinse. The risk of tippy dyeing on wool is increased when the dyebath pH falls below 4.0 or when the temperature rise exceeds 1 °C/min; damaged fibre tips adsorb disproportionately and produce a skittery appearance. In silk dyeing, the top temperature is limited to 85–90 °C to reduce fibre fibrillation; a level pH of 4.5–5.0 is maintained with acetic acid/sodium acetate buffer. Light fastness on wool at 1/1 standard depth is evaluated according to ISO 105-B02; supplier documentation commonly indicates ratings between 5 and 6 on the blue wool scale, but independent verification on the specific substrate lot is required before production release.
In anodized aluminium colouring, Acid Green 27 is introduced into the dye bath at 55–65 °C and pH 5.5–6.0, where the anionic dye adsorbs onto the hydrated aluminium oxide layer formed by sulfuric acid anodizing. The pore diameter and oxide thickness from the anodizing step control uptake: for architectural profiles anodized to 10–15 µm oxide thickness, exposure to 1–2 g/L dye for 10–20 min yields medium green shades, but saturation occurs when surface dye sites are occupied. The sealing step after dyeing, usually in boiling deionized water at 96–100 °C for 30–45 min, hydrolyses the pore walls and locks the dye within the oxide structure. Acidic sealing below pH 5.0 may strip weakly adsorbed dye; nickel acetate sealing at 0.5–1.0 g/L nickel is used where improved corrosion resistance is specified, but the dye bath is maintained separately to avoid precipitation with anionic auxiliaries. Colour fastness of the sealed anodic layer is assessed under accelerated light exposure according to ISO 2135; acceptance criteria are set by the architectural specification rather than by the dye supplier.
In chrome-tanned leather drum dyeing, Acid Green 27 is added after neutralization at pH 4.0–5.5 and 55–60 °C, with formic acid used as the final exhaustion agent. Penetration is evaluated by cut-edge examination; through-colour acceptance is typical for garment leather at 1.0–2.0 % offered mass. Hard water above 150 mg/L CaCO₃ requires polyphosphate or EDTA addition to avoid metal-dye complexes that reduce brilliance and produce surface bronzing. Published data for Acid Green 27 in leather applications is limited; processing parameters are transferred from general acid dye ranges and must be confirmed by pilot drum trials.
Differentiation from Acid Green 25 arises primarily from the 5,8-dihydroxy substitution on the anthraquinone ring. Acid Green 25 is an arylamino-substituted anthraquinone acid dye that lacks the additional hydroxyl donor groups; as a result, Acid Green 27 typically shifts toward a yellower, slightly duller green on polyamide and shows different sensitivity to copper and iron ions in hard water. Acid Green 27 is also distinguished from pre-metallized green acid dyes by migration behaviour: Acid Green 27 possesses moderate to good migration under acid conditions, whereas many pre-metallized greens exhibit higher wet fastness but lower migration and require longer levelling phases. The table below summarizes the structural and application differentiation for Acid Green 27 and Acid Green 25.
| Criterion | C.I. Acid Green 27 | C.I. Acid Green 25 |
|---|---|---|
| Colour Index number | C.I. 61580 | C.I. 61570 |
| Molecular substitution | 5,8-dihydroxy on anthraquinone | No 5,8-dihydroxy substitution |
| Shade direction on polyamide | Yellower, slightly duller green | Bluer, brighter green |
| Hard-water metal sensitivity | Higher; chelating agent required above 150 mg/L CaCO₃ | Lower; still sensitive to iron |
| Migration behaviour in acid bath | Moderate to good | Moderate |
| Fastness development | Requires cationic after-fixation on wool for wet fastness | Similar after-fixation requirement |
Published fastness data for direct comparative testing of Acid Green 27 and Acid Green 25 on all substrates is limited; shade direction and migration statements are based on structural differences and mill-level observations. In hard water, Acid Green 27 may exhibit weaker colour yield if copper or iron ions complex with the hydroxyl groups; addition of an iron sequestrant at 0.2–0.5 g/L is required before dye addition.
Before production use, the supplier safety data sheet and current REACH registration status must be checked for the specific commercial formulation, because Acid Green 27 is supplied as a preparation that may contain sodium sulfate or sodium chloride as standardizing diluents. For textile articles intended for skin contact, the dyed fabric must meet the fastness requirements of Oeko-Tex Standard 100 Annex 4 or equivalent ISO 105 test protocols; the dye itself has no independent certification. Acid Green 27 is not recommended for indirect food-contact applications unless migration testing is conducted in accordance with EU Regulation 10/2011 or FDA 21 CFR parts 170–199 as applicable.
In the dyebath, Acid Green 27 must not be combined with cationic fixing agents, cationic levelling agents, or quaternary ammonium softeners because coacervate precipitation occurs at ambient pH. Pre-dissolved Acid Green 27 should not be mixed with concentrated mineral acid before dilution; localized pH below 1.0 can protonate sulfonate groups and reduce solubility. In powder handling areas, dust extraction is required to keep respirable dust below the national occupational exposure limit; although Acid Green 27 is not flammable, accumulated dust on horizontal surfaces can form an explosive dust cloud when dispersed, so housekeeping follows the general requirements of ATEX Directive 1999/92/EC for non-metallic combustible dusts.
