Section
| HS Code | 301016 |
| Productname | Solvent Blue 4 |
| Colorindexname | C.I. Solvent Blue 4 |
| Casnumber | 6786-83-0 |
| Molecularformula | C16H14N2O2 |
| Molecularweight | 266.30 g/mol |
| Chemicalclass | Anthraquinone solvent dye |
| Appearance | Blue powder |
| Color | Blue |
| Form | Powder |
| Meltingpoint | Approximately 220-222 °C |
| Solubility | Insoluble in water; soluble in organic solvents |
| Primaryuse | Coloring plastics, inks, waxes, coatings, gasoline, and oils |
| Storageconditions | Store in a cool, dry, well-ventilated place with container tightly closed and away from light |
| Stability | Stable under normal handling and storage conditions |
As an accredited Solvent Blue 4 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Solvent Blue 4 is packaged in 25 kg fiber drums with polyethylene liners, securely sealed and GHS-labeled. |
| Container Loading (20′ FCL) | Solvent Blue 4 loaded in a 20′ FCL container, palletized, labeled, sealed, and secured for safe ocean transport. |
| Shipping | Ship Solvent Blue 4 in tightly closed, properly labeled containers, protected from moisture, light, and contamination. It is generally not classified as dangerous goods for transport; confirm with the current SDS and applicable DOT/IATA/IMDG rules. Keep away from oxidizers and include the SDS with shipment. |
| Storage | Store Solvent Blue 4 in a cool, dry, well-ventilated area away from direct sunlight, heat, ignition sources, and strong oxidizers. Keep containers tightly closed and protect from moisture. Avoid dust generation, use appropriate PPE, and do not store near food, drink, or animal feed. Follow local regulations and good housekeeping practices. |
| Shelf Life | Shelf life is generally 24–36 months when stored sealed in a cool, dry, dark place, away from heat and moisture. |
Solvent Blue 4 (C.I. 44040, CAS 6786-83-0) is handled in solvent-borne liquid ink manufacture as a molecularly dispersible triarylmethane dye, not as a pigment dispersion. In non-food flexible packaging gravure and flexographic line work the dye is first dissolved at 5–15 wt% in an ethyl acetate–ethanol–n-propyl acetate co-solvent or in a ketone-containing blend, then filtered through 10 µm bag media before letdown into nitrocellulose-polyurethane or PVB binder systems. The final liquid ink is maintained at 22–28 s flow time on a 4 mm ISO cup at 23 °C per ISO 2431:2019; readings above 30 s on a conventional flexographic deck typically indicate incomplete redissolution and produce pinholing on corona-treated polyethylene at 38–40 mN/m. Unlike copper phthalocyanine pigment dispersions, the dye does not deposit on gravure blade edges, but its low molecular mass requires migration testing when the printed substrate is subsequently extrusion-laminated to LDPE sealant webs. A 10-day 40 °C Tenax® exposure under EN 1186-14 is used to screen for migration into dry food simulant; without a validated barrier, the dye is limited to surface-print structures, non-food laminations, or applications where an aluminium foil or metallised PET layer provides a functional barrier under EU Regulation 10/2011.
In ABS and SAN masterbatch production on a 40:1 L/D twin-screw extruder, Solvent Blue 4 is pre-blended with a styrenic carrier resin at 0.2–0.5 wt% of the masterbatch and let down to 0.02–0.1 wt% in the final injection-moulded or extruded article. The melt temperature at the die is held below 220 °C; vent vacuum of -0.06 MPa is applied to strip residual solvent introduced with the dye. When residence time extends beyond 12 min or melt temperature surges past 240 °C, the blue shifts green by partial dealkylation at the triarylmethane central carbon; the resulting ΔE*ab against a retained standard plaque is quantified per ISO 11664-4 and should remain below 2.5. Melt flow rate after letdown is verified per ISO 1133-1:2022 at 220 °C/10 kg for ABS and compared with the unfilled control; deviation beyond ±15% normally signals dye-induced plasticization or early degradation. At final loadings below 0.05 wt%, surface migration to the pelletizing die face can increase contact angle to above 85° on injection-moulded test plaques. Published thermal stability data for Solvent Blue 4 in polypropylene and other high-temperature polyolefins are limited; processing above 220 °C requires masterbatch heat-resistance validation by controlled extrusion retention before production approval.
Solvent Blue 4 is incorporated into dye-based interior wood stains by dissolving it in methoxypropanol or 2-butanone containing a ketone–aldehyde resin; the working solution is filtered through 5 µm depth media and adjusted to 80–120 mPa·s at 23 °C on a Brookfield RV viscometer, spindle 2 at 50 rpm. For oak veneer curtain coating, higher viscosity closes grain definition and produces blotchy absorption. During forced drying at 35–45 °C, residual 2-butanone above 3 wt% promotes fine-capillary dye migration into latewood; residual solvent is checked by infrared moisture balance per ASTM D7232 and kept below 1.5 wt% before two-pack polyurethane sealing. The stained substrate is assessed for light fastness under xenon-arc exposure by ISO 105-B02; at 100 h, the blue wool reference rating decreases in the absence of a hydroxyphenyl-triazine UV absorber in the topcoat. Terminal components include interior furniture, decorative millwork and interior veneer panels where the coating system qualifies under applicable architectural VOC limits.
Where Solvent Blue 4 is evaluated for visible blue marking of hydrocarbon streams, the dye is not charged as dry powder into the finished fuel tank; it is prepared as a 10–20 wt% stock solution in aromatic or high-boiling ester solvent and metered by a plunger pump at the product quill downstream of final filtration. Homogeneity after inline recirculation is confirmed by ASTM D1500 colour scale; stratification after 24 h at 4 °C must be absent before release. Because triarylmethane dye backbones are sensitive to oxidative fading, peroxide numbers above 10 mmol/kg per ASTM D3703 or dissolved copper above trace concentrations require a metal chelator and antioxidant top-treat. Quantitative low-ppm marker loadings for tax-enforcement programmes are proprietary to the service provider; published data for this specific configuration is limited. The product is excluded from aviation turbine fuel handling unless water separation per ASTM D3948 and thermal oxidative stability per ASTM D1403 are revalidated with the marked fuel blend.
In paraffin candle manufacture Solvent Blue 4 is pre-dissolved in stearic acid or an ester-based solubilizer at 60–70 °C before addition to the wax melt at 75–85 °C. Direct powder addition at melt temperatures below 70 °C leaves undissolved dye particles that nucleate paraffin crystal growth and visible specking. Final dye concentration is typically 0.02–0.2 wt%; higher loadings produce surface exudation on the finished candle after 72 h at 30 °C, detected as ΔE*ab increase on a white tissue rub test. Soy wax blends require a two-stage high-shear premix at 80 °C because polarity differences reduce dye solubility; a 5 wt% aromatic hydrocarbon co-solvent is used in paraffin systems where the dye does not fully redissolve. Combustibility and wick performance are assessed by candle fire-safety testing per ASTM F2417-17; organic dye loading must not alter melt pool diameter beyond the specified container opening.
Solvent Blue 4 is used in PVB-based foil lidding inks at 1.0–2.5 wt% of the liquid ink, applied by roto-gravure at 80–120 m/min with drying tunnel outlet web temperature maintained below 60 °C to avoid activating slip additives in the heat-seal coating. Anilox specifications of 600–800 lines per inch and 8–10 cm³/m² are used for fine highlight text, because the dye solution fills gravure cells without pigment particle settling. Heat-seal adhesion after lidding is tested by 180° peel per ASTM F88; minimum seal strength for medium-barrier lidding is typically 6 N/25 mm. The dye must not migrate into the sealant layer during a 200 °C/1.5 s dwell; if migration is measured by isopropanol wipe removal beyond 30 strokes on the printed side, an overprint lacquer is required. This application is restricted to printed foil structures where the heat-seal layer is not in direct contact with food surfaces unless a migration study under EU Regulation 10/2011 demonstrates compliance.
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Solvent Blue 4 is a triarylmethane solvent dye identified by Colour Index designation C.I. 44040, assigned CAS 6786-83-0, and supplied commercially as dark blue powder or as a liquid dispersion in plasticizer or solvent. The chromophore corresponds to the free base of Victoria Blue B, with formula C33H33N3 and molecular weight 471.64 g/mol. A dilute ethanol solution shows an absorption maximum near 615 nm when scanned by UV-Vis spectrophotometry, and the shade is typically measured against a retained reference lot under D65/10° illumination using colour difference equations from ASTM D2244. Typical commercial specifications list assay by spectrophotometry not less than 98%, moisture by Karl Fischer below 0.5%, and ash after ignition below 0.2%. Commercial models vary by manufacturer; available forms include high-strength powder, granular, and 30–45 wt% liquid dispersion in DINP or aromatic solvent. Liquid dispersions reduce dust generation in ink plants, while powder grades offer lower freight cost per unit of chromophore. The product is used for tinting of hydrocarbon solvents, oils, waxes, printing inks, wood coatings, leather finishes, and limited transparent thermoplastics. Batch-to-batch variation in shade, expressed as CIELAB ΔE*ab, is commonly controlled below 0.8 units for high-purity grades, while published data for technical grades is limited.
Solubility at 25 °C in aromatic hydrocarbons is typically above 100 g/L; in methyl ethyl ketone and ethyl acetate the dye also dissolves readily, but water solubility remains below 0.1 mg/L. The hydrophobic free-base structure allows direct dissolution in toluene, xylene, and plasticizers such as DINP without milling. In waterborne binders, a co-solvent such as propylene glycol monopropyl ether is required to prevent precipitation during let-down. The exact solubility in mixed solvents is not fully described by single-solvent data; supplier certificates should be used to adjust blends for alcohols, glycol ethers, and aliphatic hydrocarbons.
Compared with aminoanthraquinone solvent blues, Solvent Blue 4 has a higher molar extinction coefficient at equal mass concentration, but the central carbon atom in the triarylmethane structure is vulnerable to oxidative cleavage. Accelerated xenon-arc exposure under ISO 105-B02 places Solvent Blue 4 below Solvent Blue 35 and Solvent Blue 36 in Blue Wool ratings; exact published numeric ratings vary among dye manufacturers and depend on binder chemistry. Consequently, exterior coatings, automotive interior parts, and acrylic glazing exposed to continuous UV should not rely on Solvent Blue 4 as the primary colourant. Acceptable use areas include gravure and flexographic printing inks, marker inks, wood stains, leather base coats, shoe polish, fuel dyes, and industrial oil identification. In such systems, dye loadings of 0.5–5 wt% are used without the milling step required for phthalocyanine pigments. The resin system influences retention: nitrocellulose and vinyl chloride-vinyl acetate binders offer better short-term solvent resistance but do not improve photostability.
Direct addition of neat powder at the feed throat of a single-screw extruder is not recommended because localized dye concentration can cause visual streaks and agglomerates. Supplier processing guides recommend preparing a 10–20 wt% predispersion of Solvent Blue 4 in mineral oil, DINP, or a low-molecular-weight polyethylene wax at 80–90 °C under low-shear mixing. The premix is then metered into a co-rotating twin-screw extruder with L/D ratio above 40:1 and melt temperature controlled within 180–220 °C for general-purpose polystyrene. Residence time above 2 min at melt temperature can shift the shade toward a duller, greener blue and reduce tinctorial strength. Published degradation kinetics for Solvent Blue 4 in specific polymer melts are limited; therefore, production-scale validation should include thermogravimetric analysis at 10 °C/min under nitrogen, and the addition level should be adjusted from 0.01 wt% downward when thin-wall moulded parts show colour drift. The same approach applies to rigid PVC, although tin stabilizers can interact with the dye and should be checked by laboratory drawdown.
The molecular weight of Solvent Blue 4 is low relative to anthraquinone blue dyes, and this increases diffusion through plasticized matrices. Contact migration testing following ISO 15701 conditions, involving a coloured PVC or PU sheet pressed against a white plasticized PVC receptor at 50 °C for 24 h, typically reveals visible staining when Solvent Blue 4 is used above 0.02 wt%. Formulators seeking non-bleeding blue shades in artificial leather, coated textiles, and soft-touch overmoulding often select Solvent Blue 36 or Solvent Blue 104 instead. Where Solvent Blue 4 is retained in flexible PVC, addition levels are kept between 0.005 wt% and 0.015 wt%, and a sealing topcoat is applied to reduce contact transfer. The same mobility is advantageous in marker inks and fuels, where uniform distribution and low resistance to transfer are desired. Ionic salts or polar additives can increase bloom if the dye is not fully compatible with the plasticizer, so compatibility testing in the actual formulation is required.
In surface-printing gravure inks for coated paper, aluminium foil, and polyester film, Solvent Blue 4 is commonly dissolved in a blend of ethanol, ethyl acetate, and propylene glycol monomethyl ether. Viscosity is adjusted to 15–25 s by a 3 mm ISO flow cup at 25 °C, and the dye concentration in liquid ink is held near 5 wt% to produce acceptable optical density at 615 nm. Press speeds of 120–150 m/min are typical for solvent-based surface printing, but slow solvents such as cyclohexanone may cause highlight dot bridging on heat-sensitive substrates if drying capacity is insufficient. Solvent Blue 4 dissolves without pigment settling, which reduces nozzle and cell blockage during extended press runs. The printed shade is strongly dependent on the solvent-release rate of the binder; rapid solvent evaporation can cause bronze-like surface effects on coated papers.
Solvent Blue 4 differs from pigmentary phthalocyanine blues in dispersion mechanics. Phthalocyanine pigments such as C.I. Pigment Blue 15:3 require high-energy grinding, whereas Solvent Blue 4 dissolves under low-shear agitation. This difference is observable in low-viscosity systems: a 40 wt% phthalocyanine paste may show thixotropic behaviour, while a 40 wt% solution of Solvent Blue 4 in a compatible solvent remains Newtonian within the shear-rate range used for inkjet and fibre-tip pen production. Because the dye is molecularly dispersed, continuous inkjet systems do not undergo the same particulate settling and orifice wear that can occur with dispersed pigments. However, the dye solution does not provide the same opacity or colour intensity under backlit conditions as a pigmented system. In transparent applications such as tinted acrylic or polystyrene, the dye is preferred because it imparts clarity and high transparency, whereas pigments scatter light and generate haze.
| Property | Solvent Blue 4 | Solvent Blue 35 | Solvent Blue 36 |
|---|---|---|---|
| Dye class | Triarylmethane | Anthraquinone | Anthraquinone |
| Colour Index | C.I. 44040 | C.I. 61554 | C.I. 61550 |
| CAS | 6786-83-0 | 17354-14-2 | 14233-37-5 |
| Lightfastness per ISO 105-B02 | Blue Wool 3–4 typical | Blue Wool 6–7 typical | Blue Wool 6–7 typical |
| Processing ceiling in polyolefins | Approx 220 °C | Up to 280 °C | Up to 280 °C |
| Migration tendency in plasticized PVC | High | Moderate | Low |
| Typical use | Short-run inks, markers, wood stains, fuel markers | Engineering plastics, acrylics, PET | Engineering plastics, PET, lubricants |
Solvent Blue 4 is not included among colourants authorized for food-contact polymers under FDA 21 CFR Part 178.3297 or EU 10/2011. Formulations intended for food packaging, toys, or medical applications should therefore be evaluated separately and should not rely on generic regulatory clearance. Under REACH, the substance is subject to industrial exposure scenario assessment; downstream users must verify the assigned use against the extended safety data sheet. RoHS compliance does not generally restrict organic solvent dyes, but metal content in technical dye preparations should be checked by ICP-OES against EN 71-3 migration limits when toy inks or other child-contact articles are under development. For non-food industrial coatings, the dye is normally specified through workplace exposure limits and dust-control measures rather than product-contact clearances. Analytical certificates for high-purity grades typically report heavy metal concentrations below the detection limits of the test method; if an end-use specification requires lower values, additional purification may be needed.
UV-Vis spectrophotometric assay of Solvent Blue 4 is performed by dissolving 0.01 g of dye in 100 mL of absolute ethanol and measuring absorbance at 615 nm in a 10 mm quartz cuvette. Because the triarylmethane chromophore responds to solvent polarity and pH, the ethanol solution should be maintained between pH 5 and 7 during measurement. Tinctorial strength relative to a reference lot is determined by preparing matched drawdowns in a clear binder at 1 wt% dye solids and applying ASTM D2244 colour difference analysis under D65/10°. This method is suitable for incoming inspection and release control, but it does not predict long-term lightfastness or migration in the final article; those properties require the corresponding ISO test methods described above. For resin-bound systems, transmission spectra of 2 mm plaques can be measured by ASTM D1003 haze and luminous transmittance equipment to confirm whether the dye remains fully dissolved or begins to aggregate.
Bulk handling of Solvent Blue 4 powder generates dust that can stain equipment, skin, and clothing. Local exhaust ventilation with capture velocity of 0.5 m/s is advised at bag-emptying, sieving, and weighing stations. Operators should use particulate respirators conforming to EN 140 and nitrile gloves tested against EN 374 when handling bulk powder. Spills should be wetted with ethanol and absorbed onto inert material to prevent dry dust dispersion. Storage in tightly closed containers at temperatures below 40 °C and away from direct sunlight minimizes moisture uptake and shade drift. The product should not be combined with strong oxidizing agents, acids, or reducing agents in concentrated form because the triarylmethane chromophore is susceptible to redox bleaching. In liquid dispersion form, drums should be homogenized before sampling because slow settling of any insoluble by-products can affect apparent strength.
