Section
| HS Code | 355357 |
| Product Name | Solvent Green 7 |
| Synonyms | Pyranine; HPTS; 8-Hydroxypyrene-1,3,6-trisulfonic acid trisodium salt |
| Color Index Number | CI 59040 |
| Cas Number | 6358-69-6 |
| Molecular Formula | C16H7Na3O10S3 |
| Molecular Weight | 524.37 g/mol |
| Appearance | Yellow-green to green powder |
| Solubility | Soluble in water; slightly soluble in polar organic solvents; insoluble in nonpolar solvents |
| Fluorescence Color | Green |
| Excitation Maximum | Approximately 450 nm (pH-dependent) |
| Emission Maximum | Approximately 510 nm in water |
| Ph Sensitivity | pH-sensitive fluorescent dye with pKa approximately 7.3 |
| Chemical Class | Pyrene trisulfonate sodium salt |
| Charge | Anionic trisulfonate |
As an accredited Solvent Green 7 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Solvent Green 7 is supplied in 25 kg net fiber drums with polyethylene liners, securely sealed for transport and storage. |
| Container Loading (20′ FCL) | Solvent Green 7 is loaded into a 20-foot FCL container in sealed, labeled packages, securely stowed for ocean transport. |
| Shipping | Solvent Green 7 is typically shipped as a non-hazardous, moisture-sensitive powder in sealed, labeled containers at ambient temperature, protected from light and humidity. Avoid dust generation and use appropriate PPE. It is generally not regulated for transport under DOT, IMDG, or IATA unless local requirements apply. |
| Storage | Store Solvent Green 7 in a tightly closed, labeled container in a cool, dry, well-ventilated area away from direct sunlight, heat, moisture, and incompatible oxidizers. Protect from dust and physical damage; keep containers upright and segregated from foodstuffs. Use secondary containment where appropriate; avoid dust inhalation and eye/skin contact. Follow local regulations and SDS requirements. |
| Shelf Life | Shelf Life: Stable for several years when kept sealed in a cool, dry, dark place, protected from moisture and light. |
At melt temperatures of 220 °C to 250 °C, Solvent Green 7 is incorporated into general-purpose polystyrene (GPPS) or polymethyl methacrylate (PMMA) by let-down from a 2% active masterbatch. The final dye concentration in fully transparent injection-moulded sections is maintained between 0.005 wt% and 0.1 wt%; for a 2 mm thick part, higher concentrations are avoided because edge-stress birefringence and visible hue shift become measurable under polarised light inspection. On a 40:1 L/D co-rotating twin-screw extruder, direct powder addition at the hopper has been observed to generate die-lip streaking and increased screen-pack differential pressure, whereas masterbatch let-down at 1–2% final carrier content yields acceptable dispersion as verified by 25 µm screen packs and subsequent optical inspection at 20× magnification. The injection moulding window for PMMA uses a barrel profile of 210–240 °C, back pressure of 50–80 bar, and a screw cushion of 3–5 mm to avoid excessive residence time in the compression zone. Melt-flow rate is verified according to ISO 1133-1:2022, and transmission haze is assessed according to ISO 13468-1:2019. For food-contact packaging in the European Union, the compound is supported by a declaration of compliance under Regulation (EU) No 10/2011 only if migration testing of the finished article in the appropriate simulants demonstrates conformity with the specific migration limit applicable to the dye; analogously, United States food-contact status requires confirmation against FDA 21 CFR § 178.3297. For children’s articles falling under the scope of Directive 2009/48/EC, extractable elements are tested according to EN 71-3:2019+A1:2021. Terminal finished product types in this scenario include edge-lit light guide plates for automotive interior displays, transparent indicator lenses, cosmetic closures, and control-panel windows for household appliances.
| Matrix | Let-down ratio (wt% of compound) | Melt-flow verification | Optical verification |
|---|---|---|---|
| GPPS | 0.005–0.08 | ISO 1133-1:2022 | ISO 13468-1:2019 |
| PMMA | 0.01–0.10 | ISO 1133-1:2022 | ISO 13468-1:2019 |
Bead-mill dwell time controls solvent dye dissolution in ethyl acetate/propanol systems. In a typical nitrocellulose-polyurethane gravure ink, Solvent Green 7 is added at 0.5–2.0 wt% of the total formulated ink; the let-down is delayed until the grind phase reaches a Hegman gauge reading of 5–6 µm because early addition raises mill viscosity and reduces bead impact energy. Production-scale horizontal bead mills with 0.6–1.0 mm zirconium oxide beads are operated at jacket temperatures below 40 °C to prevent solvent evaporation and dye precipitation on the mill screen. The formulated ink is reduced to 15–18 seconds in a DIN 4 cup according to DIN 53211 at 23 °C for gravure application; cylinder cell depths of 30–40 µm transfer dried film weights of approximately 2–4 g/m². Compliance for printed food packaging requires that the finished print meet the relevant positive-list and migration requirements of Regulation (EU) No 1935/2004, including any specific measure applicable to printing inks where harmonised national legislation applies; prints for toys are assessed under EN 71-3:2019+A1:2021 for extractable colourants, and Swiss Ordinance SR 817.023.21 is referenced for packaging ink formulations where branded food-contact assurance is required. Solventborne inks based on ethyl acetate and isopropanol show poor solubility of Solvent Green 7 at ketone concentrations below 20%; undissolved dye deposits on gravure cylinder lands and produces specking defects on metallized substrates. Terminal finished products include aluminium foil lidding, vacuum-metallized paper labels, polyester film overwrap, and gift-wrap gravure prints.
Polyester dope dyeing with Solvent Green 7 is performed in a 32:1 L/D co-rotating twin-screw extruder at melt temperatures of 280–295 °C. The dye is pre-dispersed in a polyester carrier or added as a 10–20% solid masterbatch into dried PET chip at a final dye loading of 0.05–0.30 wt%. Pre-drying of the PET to 50 ppm moisture or lower is mandatory because hydrolytic chain scission above 280 °C causes molecular weight loss, shade drift, and spinneret pressure instability. Vacuum degassing is maintained below 100 mbar absolute to remove low-molecular-weight volatiles; vent-port fouling is an observed failure mode when the vacuum line temperature falls below the sublimation deposit zone. Spin packs with 0.2–0.4 mm spinneret holes and 20–50 µm filtration media are used; a rapid filter differential-pressure increase above the normalised baseline indicates dye aggregation and requires a reduction in let-down ratio or a switch to a fully compounded chip. Fibre draw ratios of 3.0–3.5:1 and spin finish application of 0.3–0.7% by mass are set to stabilise winding and subsequent weaving. Compliance for automotive interior textiles is generally assessed against ISO 105-B02:2014 for light fastness with a minimum rating of 6 for instrument panel fabrics, ISO 105-C06:2010 for domestic and industrial washing, and OEM-specific VOC emission protocols such as VDA 278:2021. REACH Annex XVII entries for restricted substances in articles remain applicable to the finished textile regardless of fibre type. Published mechanical property data for dope-dyed PET at the upper 0.30 wt% loading is limited; yarn tenacity verification according to ISO 2062:2009 is therefore required on the exact spun yarn before production release. Terminal finished products include automotive seat belts, interior upholstery fabric, webbing, outdoor strapping, and high-tenacity sewing thread.
When calendered flexible PVC containing 35 phr diisononyl phthalate (DINP) is coloured with Solvent Green 7, the dye is pre-dispersed in a plasticizer slurry using a high-shear dissolver and then added at 0.01–0.2 phr based on PVC resin. Two-roll mill compounding at 160–180 °C is maintained for 5–8 minutes after complete plastification; insufficient mixing at lower roll friction ratios has been linked to visible green streaks in subsequent calendered sheet. Calendering is conducted at gap settings of 0.2–0.8 mm, with embossing roll temperatures of 70–110 °C to replicate grain without causing dye migration to the embossing roll surface. For flexible PVC films marketed in the European Union, the phthalate restrictions set out in REACH Annex XVII entries 51 and 52 apply, and the colourant formulation must not introduce lead, cadmium, mercury, or hexavalent chromium above limits set by Directive 2011/65/EU Annex II; total heavy-metal content is verified by ICP-OES following EN 71-3:2019+A1:2021 preparation for toy-contact films. Because Solvent Green 7 in high-plasticizer PVC exhibits measurable migration to white ABS under 70 °C contact load, press-out tests at 70 °C under 50 kPa for 24 h are conducted before specifying the dye for two-colour co-extruded profiles. Terminal finished products include automotive interior decorative film, edge banding, advertising films, and stationery covers.
In fully refined paraffin, the solubility boundary of Solvent Green 7 is controlled by n-alkane crystallinity rather than by heat stability. The dye is introduced as a 1% dispersion in a compatible liquid paraffin or oxygenated wax ester and let down to a final wax concentration of 0.001–0.02 wt%; concentrations above 0.02 wt% in pure paraffin frequently produce colour streaking on cooling because the dye partitions into the shrinking amorphous phase. Molten wax is held at 80–100 °C and stirred at low shear for 15–20 minutes to avoid entrained air; cooling is controlled at 0.5–2 °C/min through the paraffin crystallization range of 50–70 °C to prevent surface bloom. For candle formulations, the finished assembly is evaluated for flame behaviour under ASTM F2417-17, although that standard does not quantify colourant migration; migration to polypropylene packaging is assessed by a contact-stain test at 40 °C for 72 h. In the United States, the use of Solvent Green 7 in candles intended for food-contact ambience applications requires confirmation that the dye is listed or otherwise acceptable under FDA 21 CFR § 178.3297 or the relevant household product enforcement discretion; EU REACH registration and CLP classification remain applicable regardless of end use. Terminal products include votive candles, paraffin container candles, wax melts, and decorative novelty candles.
Before spray application to buffed bovine hides, Solvent Green 7 is dissolved in a polyurethane topcoat lacquer at 2–5 wt% of non-volatile lacquer solids; higher loading can create bronzing on high-gloss finishes because the dye migrates to the surface during forced-air drying at 50–70 °C. The lacquer is reduced to 20–22 seconds in a DIN 4 cup according to DIN 53211 and applied in 2–4 cross-spray coats with a dry film thickness of 10–25 µm per coat. Spray booths operate at 20–25 °C and 50–65% relative humidity; at relative humidity above 70%, isocyanate-containing topcoats become susceptible to bubble formation and reduced crosslink density. Compliance for leather supplied to footwear and garment markets requires that the finished leather meet chemical restrictions under the ZDHC Manufacturing Restricted Substances List, including colourant-related limits for chlorinated phenols and certain arylamines; extractable heavy metals are tested by DIN EN ISO 17072-1:2019. EU REACH Annex XVII restrictions apply to the finished leather article independently of the dye formulation. Terminal finished products include automotive leather interior components, shoe uppers, handbag leather, and garment leather.
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Solvent Green 7 is an anthraquinone colorant indexed under C.I. 61570 and identified by CAS 128-87-0; the molecular formula is C28H22N2O4, and the molecular weight is 450.49 g/mol. Commercial models are supplied as dry powder, low-dust granular, or pre-dissolved liquid concentrate at 20–40 wt% dye in carriers such as dioctyl phthalate, triacetin, or proprietary alkyl ester blends; model designations differ among manufacturers, but the color index and CAS number remain the primary identity codes. The product provides transparent green coloration in amorphous thermoplastics, acrylics, styrenics, polycarbonate, and selected polyester preforms where particulate pigments would generate unacceptable haze or light loss. A solvent dye dissolves into the melt or liquid carrier and does not require the high-shear grinding and deagglomeration step associated with copper phthalocyanine Pigment Green 7 (C.I. 74260). Consequently, optical clarity can be retained in 2 mm plaques measured under ASTM D1003, but migration and extraction resistance are polymer-dependent and must be verified against end-use standards before specifying the colorant.
In injection-stretch blow molding of PET bottle preforms, barrel temperatures commonly span 270–295 °C and can exceed 300 °C for short residence times. Solvent Green 7 is an anthraquinone structure with higher thermal stability than many monoazo solvent dyes, but published thermogravimetric data for this specific configuration is limited and varies by carrier. Before production use, a thermal stress test on the compounded material under ISO 11358-1 or an actual preform injection trial with hot-runner residence times of 2–5 min should establish the onset temperature of absorbance shift. Pre-drying of PET resin to a residual moisture level below 30 ppm in a desiccant dryer at 160–170 °C for 4–6 h is required; hydrolytic degradation caused by moisture above this threshold produces acetaldehyde and intrinsic-viscosity loss, and the dye may shift oligomer solubility in the dryer and gate areas. A mold clamp force of 1,000–3,000 kN per 64-cavity preform tool is typical but does not influence dye thermal survival directly; the critical variable is residence-time distribution in the hot runner. If preform haze increases above 1.5 % under ASTM D1003, the formulation should be switched to a granular masterbatch rather than a liquid concentrate because the carrier may phase-separate in the melt stream.
At the analytical level, a double-beam UV-Vis spectrophotometer with 1 nm spectral bandwidth is used to measure the absorption maximum of Solvent Green 7 in toluene or polymer film; batch-to-batch tinctorial strength is typically controlled to ±2 % relative to a standard. CIELAB coordinates under D65/10° observer are used for release testing; a ΔE*ab of 0.5 units or less against the reference is a common internal limit, but buyer specifications must define the tolerance. Transmission haze of molded plaques is measured per ASTM D1003; the dye itself contributes no particulate haze if fully dissolved, while undissolved agglomerates above 0.5 µm can raise haze by light scattering. This is why pre-dissolved liquid grade or masterbatch is preferred for critical optical applications.
In co-rotating twin-screw extrusion of polyolefin or styrenic masterbatch, a 40:1 L/D machine with distributive mixing elements and barrel zones from 180 °C to 230 °C is commonly used for Solvent Green 7 at 0.5–2.0 wt% dye loading in a compatible carrier. The dye is pre-blended with resin powder or metered via side feeder; peak shear rate should not exceed 1,500 s⁻¹ if undissolved dye agglomerates are to be avoided, because excessive shear can generate local temperature spikes that degrade the anthraquinone chromophore and shift the transmission spectrum. In single-screw injection molding, a back pressure of 4–8 bar and screw rotation speed below 150 rpm are sufficient for homogeneous distribution after dissolution. A production-scale issue observed in ABS is viscosity reduction of 2–6 % when the dye is added as a 30 wt% DOP liquid at high letdown; this is not a plasticizing defect if the molder adjusts hold pressure accordingly, but it must be accounted for in the process window. No dispersion step is required, so the grinding and color-strength development problems associated with copper phthalocyanine pigments are absent.
Because solvent dyes dissolve at the molecular level, replacing Pigment Green 7 with Solvent Green 7 in polycarbonate optical components eliminates the 0.5–1.0 µm scattering centers associated with pigment agglomerates; residual haze under ASTM D1003 is then governed by polymer degradation, mold surface replication, and carrier compatibility rather than by dye particle size. Polycarbonate must be dried to 0.020 wt% moisture or less in a desiccant dryer at 120 °C for 3–4 h; melt temperature above 320 °C should be limited to short residence times, because anthraquinone chromophores can exhibit transmission loss in the 420–480 nm region when exposed to alkaline residues, free amines, or excessive thermal stress. Outdoor glazing applications require long-term weatherability testing under ISO 4892-2; published data for this specific configuration is limited, but copper phthalocyanine Pigment Green 7 normally retains a higher percentage of initial color strength after 2,000 h of accelerated weathering. The selection of Solvent Green 7 is therefore restricted to indoor or short-lifetime transparent components unless a UV-stabilized polycarbonate system is used and validated by xenon-arc test data.
Typically, commercial liquid concentrates are supplied at 20–40 wt% Solvent Green 7 dissolved in DOP, triacetin, or a proprietary alkyl ester blend, with Brookfield viscosity between 300 mPa·s and 1,200 mPa·s at 25 °C depending on carrier. Because anthraquinone dye solutions can crystallize during winter storage below 10 °C, controlled warehouse heating to 15–25 °C and gentle recirculation are required before pumping into a central color-dosing unit. For solvent-based coatings, the product dissolves in toluene, xylene, methyl ethyl ketone, and butyl acetate at ambient temperature; solubility in ethanol and water is insufficient for direct aqueous use, and the use of co-solvents must be verified by phase-separation testing before production dilution.
Migration behavior of Solvent Green 7 is matrix-dependent and cannot be predicted from chemical class alone. In nonpolar polyolefins, low molecular weight solvent dyes migrate to the surface under thermal stress; in amorphous polar matrices, migration is slower but not zero. For food-contact or toy applications, compliance requires supplier-specific listing under 21 CFR 178.3297 or Commission Regulation (EU) No 10/2011, and extraction tests should follow EN 13130-1 with food simulants appropriate to the polymer. Heavy-metal migration for toy-use formulations is evaluated under EN 71-3; organic colorants without cadmium, lead, or chromium are often acceptable, but the final article must be tested because catalyst residues from the polymer can contribute. Comparative data are summarized in Tables 1 and 2.
| Parameter | Solvent Green 7 (C.I. 61570) | Pigment Green 7 (C.I. 74260) | Solvent Green 3 (C.I. 61565) |
|---|---|---|---|
| Chemical class | Anthraquinone, hydroxy-substituted | Copper phthalocyanine | Anthraquinone |
| Transparency in 2 mm polycarbonate under ASTM D1003 | Transparent, low haze when dissolved | Opacity or scattering unless nano-dispersed | Transparent, low haze |
| Dispersion requirement | None after dissolution; avoid undissolved agglomerates | High-shear milling; particle size below 0.5 µm for full development | None after dissolution |
| Migration risk | Matrix-dependent; test per EN 13130-1 | Low in polyolefins | Higher in nonpolar polyolefins than in polar matrices |
| Lightfastness under ISO 4892-2 | Moderate; matrix-dependent | High | Moderate |
| Heavy-metal content | No copper or chromium | Contains copper | No copper or chromium |
| Regulation/Standard | Scope | Required Data |
|---|---|---|
| 21 CFR 178.3297 | US FDA colorants for polymers | Supplier listing, use level, condition of use |
| Regulation (EU) No 10/2011 | Plastics intended for food contact | Overall migration 10 mg/dm²; specific migration limit if assigned |
| EN 13130-1 | Migration test method | Simulant selection, time/temperature protocol |
| EN 71-3 | Leachable heavy metals in toys | Sample extraction and ICP-OES quantification |
| Directive 2011/65/EU RoHS | Electrical/electronic equipment | Pb, Cd, Hg, CrVI, PBB, PBDE screening |
| REACH Annex XVII entry 43 | Aromatic amine restrictions | Confirm absence of restricted amines from dye synthesis or decomposition |
Defects attributed to Solvent Green 7 in production are usually not dye degradation but carrier-induced splay or plate-out. In polycarbonate, liquid carriers with boiling points below 200 °C can volatilize at melt temperatures of 290–310 °C, producing splay on part surfaces; a pre-dissolved granular masterbatch with a polycarbonate carrier eliminates this failure. In ABS, mold plate-out at vent pins has been observed when the dye is overdosed above 0.25 wt% and the mold temperature exceeds 70 °C; vent cleaning intervals must be reduced or a higher-molecular-weight carrier selected. These effects are not universal; they depend on the commercial model and the carrier system.
When the colorant is combined with unsaturated polyester or epoxy systems, peroxides and metal-soap accelerators can generate oxidative radicals that degrade the anthraquinone chromophore; compatibility trials under the end-use cure cycle are required. Avoid contact with strong reducing agents in high-temperature melt processing because leuco-form generation can produce a reversible color shift. Dissolved dyes lower melt viscosity in some styrenics by 2–6 % and may alter mold-shrinkage anisotropy; dimensional validation under ISO 294-4 is therefore necessary for tight-tolerance components. For transparent polyethylene terephthalate sheet used in thermoforming, edge-to-center color differences can result from nonuniform melt temperature if the dye is dosed as a powder at the feed throat instead of a masterbatch.
