| HS Code | 519478 |
| Product Name | Optical Film Coloring Dye Toyobo Electronic/EL Grade |
| Chemical Class | Organic dye mixture for optical film coloration |
| Physical Form | Powder or fine particles |
| Color Range | Suitable for EL display and optical film coloring |
| Maximum Absorption Wavelength | Specific absorption peak optimized for electronic/EL applications |
| Transmittance | High optical transmittance in the desired visible range |
| Purity | High purity with minimal ionic impurities |
| Solubility | Soluble in organic solvents suitable for coating processes |
| Heat Resistance | Stable under typical EL device processing temperatures |
| Lightfastness | Excellent resistance to photodegradation under display operating conditions |
| Compatibility | Compatible with binder resins used in optical films |
| Application | Coloring of optical films and EL display components |
As an accredited Optical Film Coloring Dye Toyobo Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Sealed aluminum foil pouch under nitrogen, containing 1 kg of Optical Film Coloring Dye Toyobo Electronic/EL Grade, with moisture-barrier protection. |
| Container Loading (20′ FCL) | Container loading: 20' FCL of Optical Film Coloring Dye, Toyobo Electronic/EL Grade, packed securely in drums/pails per export regulations. |
| Shipping | This chemical ships in sealed, light-resistant containers with proper hazardous material labeling. Transport requires temperature-controlled, dry environments away from direct sunlight or moisture. Standard courier or freight options are available, with expedited shipping for time-sensitive orders. Ensure compliance with local chemical transport regulations and provide safety documentation before dispatch. |
| Storage | Store Optical Film Coloring Dye (Toyobo Electronic/EL Grade) in a cool, dry, well-ventilated area away from direct sunlight, heat sources, and open flames. Keep the container tightly sealed to prevent moisture absorption and contamination. Avoid storage near oxidizers or incompatible materials. Maintain stable temperatures and ensure secondary containment for spill prevention. |
| Shelf Life | Shelf life is typically 12 months from manufacture date when stored sealed, cool, dry, and protected from light. |
In color filter photoresist production, a Toyobo Electronic/EL Grade dye is typically pre-dissolved in PGMEA or cyclohexanone at 5–15 wt% solids. The solution is filtered through a 0.1 µm PTFE membrane before a 1,200–1,800 mm wide slot-die coater applies a wet film designed to produce 1.0–2.5 µm dry thickness. Transverse thickness variation above ±2% translates into chromaticity drift of Δu′v′ > 0.005 against CIE D65, measured with an integrating-sphere spectrophotometer per ISO 11664-2:2007. Pre-bake at 90–110°C removes the bulk solvent, while post-bake at 230°C for 20 min is the critical thermal stress for dye survival. A post-bake absorbance loss below 1.5% at the primary absorption maximum is treated as acceptable; larger loss indicates dye degradation or interaction with photoacid generators in the resist. Alkali metal, halide, and transition metal impurities are measured by ICP-MS and combustion ion chromatography, because ionic residues reduce voltage holding ratio in the finished display cell. In a production environment, particle-size distribution must also be controlled, since oversized particles above 0.5 µm cause strikethrough defects during spin coating of 1.0 µm color filter layers.
| Parameter | Method | Control window |
|---|---|---|
| HPLC dye assay | HPLC-DAD at λmax | 98.0% area minimum |
| Total alkali metals | ICP-MS after closed-vessel digestion | 1.0 ppm maximum |
| Total halides | Combustion ion chromatography | 50 ppm maximum |
| Loss on drying | Halogen moisture analyzer at 105°C | 0.5 wt% maximum |
Residual casting solvent in triacetyl cellulose acts as a polarity modifier rather than a neutral residue. When the dye exhibits solvatochromism, a differential shift of 3–12 nm in λmax between PGMEA solution and fully dried TAC matrix can move output chromaticity outside a ±0.005 Δu′v′ acceptance box. Solvent retention is measured by headspace gas chromatography on production film samples, with a typical target below 0.4 wt% for methylene chloride/methanol mixtures. A production TAC casting line often operates drying zones at 60–120°C with exhaust dew point below -20°C. If dye is added before drying is complete, local polarity stabilizes the lower-wavelength ground-state absorption and reduces color purity in the final polarizer compensation stack. Laminators observe the defect as a green-to-bluish drift in the crossed polarizer state because short-wavelength leakage increases. The corrective action is not dye reformulation but reduction of residual solvent below the threshold; below 0.3 wt%, chromaticity change is usually smaller than the repeatability of the spectrophotometric method. TAC prototypes should be conditioned at 23°C ± 2°C and 50% ± 10% RH for 24 h per ISO 291:2008 before measurement, because moisture uptake alone can shift the transmission baseline by 0.2–0.4% absolute.
In PVA-based polarizer production, a neutral-gray tint is obtained by combining iodine with a small amount of non-dichroic optical film dye in a swelling bath held at 30–45°C. The draw bath contains 2.0–3.5 wt% boric acid and 0.02–0.5 wt% dye relative to bath mass, with uniaxial stretching ratio between 4:1 and 6:1. The dye must remain soluble in the aqueous boric acid medium and must not crystallize during subsequent drying at 50–80°C. Migration is tested after lamination with pressure-sensitive adhesive and release liner in a 60°C / 90% RH chamber for 1000 h; acceptance is typically ΔE 2000 < 2.0 against the unstressed sample, measured per ISO 11664-4:2008. Batch-to-batch tinctorial strength in the PVA draw bath is checked by visible spectroscopy at the dye λmax after a fixed draw ratio; a deviation above ±2% can shift single-piece polarizer transmittance by 0.3–0.7%. The operational limitation is not thermal stability but migration in humid conditions: if dye molecular weight is too low or the dye lacks sufficient hydrogen-bonding sites, it migrates to the PSA interface and creates mura-like local color streaks visible under crossed polarizers.
Near-infrared cut filter films for CMOS image sensors are processed from a dye-doped acrylate or cyclo-olefin polymer coating with dry thickness between 5 µm and 20 µm. In a slot-die coated PET or COP web, the Toyobo Electronic/EL Grade dye is dissolved in a 15–25 wt% solids methyl ethyl ketone/cyclohexanone solvent system. The spectral target is defined by the sensor module rather than by the dye supplier: visible luminance transmission above 85% and optical density at 850 nm exceeding 3.0 are common for automotive LiDAR rejection filters, though the exact ratio depends on the photodiode spectral response. Measurement is performed with a UV-Vis-NIR spectrophotometer with 5 nm slit width and integrating sphere in transmission mode per ISO 13468-2:2021. Coating thickness uniformity must remain within ±1.5% across the web, because NIR absorbance scales exponentially with path length, and a thickness error of 3% can create a visible edge tint. Dye aggregation at high loading causes haze and scattering; the upper loading limit is determined by turbidimetric titration. After coating, films are baked at 100–130°C for 2–5 min in forced air. Residual solvent is checked by headspace GC and must remain below 500 ppm for vacuum-stable sensor assembly. The film is then die-cut and evaluated for outgassing under 85°C / 85% RH storage, because volatile species can fog the sensor cover glass.
A laminated automotive solar-control stack using a PVB or EVA interlayer is exposed to three separate heat histories: extrusion at 160–190°C, autoclave lamination at 135°C / 1.3 MPa for 90 min, and long-term solar exposure. The dye must survive the first two without sublimation or color shift and remain immobile in the plasticized interlayer during service. Migration is quantified by storing the laminate at 80°C for 500 h and measuring color change at the glass edge; uncontrolled migration appears as a colored halo with ΔE 2000 > 3.0. Weathering is evaluated with xenon-arc exposure per ASTM G154-23 or ISO 105-B02:2014; for automotive side glazing, the dye tint should retain more than 90% of initial absorbance after 1500 kJ/m² UV. The preferred incorporation route is a PVB sheet extruder with 40:1 L/D twin-screw compounding and gravimetric liquid dye injection. Predispersing in plasticizer reduces agglomerates but introduces a boiling-point constraint. A formulation containing 0.05–0.3 wt% dye in the interlayer can achieve a neutral gray or gray-green transmitted color, provided visible transmission does not fall below the regulatory boundary of 70% for the front side glazing zone. If the stack is exposed to amine-based adhesion promoters, the dye may protonate and bleach; such additives must therefore be separated from the tinted interlayer.
Incoming dye lot variance is screened by preparing a standard solution in cyclohexanone at 0.10 g/L and measuring absorbance at λmax with a double-beam spectrophotometer against a reference lot. A deviation above ±2% in absorptivity triggers dilution adjustment; a deviation above ±5% requires reformulation of the optical coating. The dyed film is drawn down on a smooth glass substrate using a 50 µm Bird applicator, dried at 120°C for 2 min, and measured for CIE L*a*b* under D65. Acceptance is ΔE 2000 < 0.35 between production lots. High-speed slot-die runs also expose dispersibility issues: rising filter pressure at 0.5 µm after 4 h of circulation indicates microgel or crystallization, not simple viscosity drift. For product environments requiring low ionic content, an additional sodium and potassium ICP-MS limit of 0.5 ppm each is often requested, because alkali metal ions migrate under electrical stress and increase leakage current in display and sensor stacks.
| Qualification area | Reference standard or method | Typical acceptance basis |
|---|---|---|
| Visible haze and luminous transmittance | ASTM D1003-21 | Haze < 1.0% for clear dyed film |
| Total luminous transmittance | ISO 13468-2:2021 | Report visible transmittance at D65 |
| Xenon light fastness | ISO 105-B02:2014 | Blue wool scale > 6 for indoor display use |
| UV weathering in laminates | ASTM G154-23 | < 2.0 ΔE 2000 after specified kJ/m² |
| RoHS restricted substances | IEC 62321-5:2013 | Below MCV for Pb, Hg, Cd |
| REACH SVHC | EU 1907/2006 Annex XVII and candidate list | No SVHC above 0.1 wt% per article |
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Toyobo Electronic/EL Grade optical film coloring dye is supplied as a purified organic colorant for solvent-borne and polymer-dope coloration of optical films. The EL designation identifies an electronic-grade refinement sequence intended to reduce ionic extractables, control particulate size, and narrow spectrophotometric batch variance relative to technical-grade solvent dyes. The product is incorporated into triacetyl cellulose, acrylic, and cycloolefin polymer casting solutions where spectral transmission, haze, and long-term lightfastness are specified by ASTM D1003-21, ASTM E313-20, and ISO 4892-2:2013. Toyobo technical documentation lists the grade as Electronic/EL Grade; no separate sub-model identifier is assigned in public product literature. Handling occurs in cleanroom environments classified under ISO 14644-1:2015 as Class 7 or tighter when dope is prepared for display film.
Solubility in production solvents must be confirmed per batch because dissolution is not equal across ketone and ester systems. Solvent systems commonly evaluated include cyclohexanone, cyclopentanone, methyl ethyl ketone, and propylene glycol monomethyl ether acetate. A production dispersion sequence wets the colorant in a low-water solvent fraction at 25–40 °C using a rotor-stator high-shear mixer, followed by dilution and polishing filtration through a 1 µm absolute media filter. Moisture ingress in methyl ethyl ketone above 0.2 mass% has been associated on coating lines with slower dissolution and the formation of insoluble dye associates. Powder storage at 25 °C and below 40% relative humidity is typical for hygroscopic electronic dyes; if a container is opened outside a dry-room with a dew point above −20 °C, pre-drying at 60–70 °C for 4 h should be validated before weighing.
Electronic-grade refinement is not a universal solubility guarantee. Residual alkali metal, alkaline earth, transition metal, and halide values are batch-reported on the certificate of analysis. Downstream users set incoming inspection limits for sodium, potassium, and chloride because these ionic species can migrate from dyed film into adjacent liquid-crystal layers and depress voltage holding ratio. Published data for this specific configuration is limited; end users compare extracted ionic content after accelerated water contact at 80 °C for 24 h using ion chromatography per ISO 10304-1:2007 and ICP optical emission per ISO 11885:2007.
Solution preparation for dyed optical film generally follows a two-stage train. The first stage is a high-shear premix vessel with jacket temperature set at 25–40 °C; the second stage is a low-shear maturation vessel where vacuum deaeration removes microfoam before slot-die coating. Dope filtration is performed through a depth filter followed by a membrane filter. Undissolved dye agglomerates trapped on the depth filter produce a differential pressure rise; a change of 0.05 MPa within 4 h is used on some production lines as an early warning for dispersion instability.
The most direct difference between the EL grade and technical-grade solvent dyes is the population of sub-visible particulates and ionic contaminants. On a 600 mm-wide slot-die coating line running at 25–35 m/min, undissolved colorant agglomerates above 1 µm can create point optical defects in dyed triacetyl cellulose film. Technical-grade dyes commonly require additional recrystallization, ion exchange, or membrane filtration before use; the EL grade is supplied in a form intended to enter direct dope filtration without these extra unit operations. Laser diffraction verifies the particle size distribution after jet milling. Acceptance ranges are aligned to the coating line’s final filter; a filter series of 1 µm absolute followed by 0.5 µm absolute is common in optical film dope preparation.
Another difference is spectral batch-to-batch control. Where a technical dye may vary in the visible absorbance maximum by ±3 nm, electronic-grade colorants for display films are frequently qualified with an absorbance-maximum tolerance below ±1 nm. The certificate of analysis for the EL grade should be consulted for the locked specification. Color coordinate drift in display edge-lit backlights becomes visible at Δu′v′ below 0.003. The grade therefore requires less lot-to-lot reformulation of compensation films and polarizer tints when the supplier maintains the purified electronic specification.
Substitution of a technical dye without requalifying the final filter can shift the dope filtration pressure curve. A rapid differential pressure increase across a 0.5 µm cartridge from 0.03 MPa to 0.15 MPa within a single production shift is treated as a colorant dispersion failure, not ordinary filter loading. This failure mode has been observed when moisture ingress or an incompatible solvent ratio creates semi-colloidal dye associates that pass visual solution inspection but blind the downstream filter.
Migration of low-molecular-weight dye in stretched or annealed optical film creates edge color drift and light-leakage artifacts. The EL grade’s lower short-chain oligomer and ionic residual content reduces plasticization of the polymer matrix, but migration remains governed by dye molecular volume, polymer free volume, annealing temperature, and adjacent-layer polarity. Accelerated stack testing at 60–85 °C evaluates colorant transfer from dyed substrates to polyvinyl alcohol polarizer and pressure-sensitive adhesive layers. Published migration data for the EL grade under specific display stack conditions is limited; qualification is therefore film-stack-specific. Users should not substitute a generic solvent dye and rely solely on visual inspection; ionic transfer to the liquid-crystal alignment layer may appear later as voltage holding ratio loss even when visible dye migration is absent.
In cast triacetyl cellulose solutions, the dye is normally introduced as a concentrated masterbatch to avoid localized viscosity reduction near the die lips. A static mixer downstream of the dosing pump disperses the masterbatch into the main polymer stream. High-shear dispersion of dry colorant directly into the main dope is avoided because rotor-stator mixing can generate microfoam and reduce film surface quality. In-line filtration pressure is monitored as an indirect control for undissolved colorant. A pressure differential exceeding 0.15 MPa across the final 0.5 µm cartridge is a typical change-out criterion; a rapid pressure rise often indicates moisture ingress or an incompatible solvent ratio rather than normal filter loading.
Colorimetric acquisition on production film uses an integrating-sphere spectrophotometer with spectral component included. Data are reduced per ASTM E1164-12 and color differences per ASTM D2244-21. The dye is selected for selective absorbance maxima between 400–500 nm or 550–700 nm depending on correction tint; the exact chromophore is not specified here because the Electronic/EL Grade can be supplied in multiple color indices.
| Qualification property | Reference method | Reported output |
|---|---|---|
| Haze after dye incorporation in cast film | ASTM D1003-21 | Δ haze vs undyed control |
| Yellowness index | ASTM E313-20 | YI |
| Lightfastness under xenon arc | ISO 4892-2:2013 | ΔE* at specified radiant exposure |
| Residual chloride by ion chromatography | ISO 10304-1:2007 | mg/kg |
| Residual metals by ICP-OES | ISO 11885:2007 | mg/kg |
| Cleanroom handling environment | ISO 14644-1:2015 | Class 7 or tighter |
For coextruded surface-protective retardation film, the dye addition point is located downstream of the gear pump to avoid additional molecular orientation and die-lip shear. The EL grade is dry-blended with polymer pellets only when the screw geometry is configured for distributive mixing; otherwise a liquid masterbatch injection is preferred. Screw torque and melt pressure are recorded because colorant aggregates can increase shear heating at the screw tip by 2–5 °C, shifting film retardation and color coordinates. Published data for this specific configuration is limited; line trials are required to establish a stable processing window. Incompatibility with amine-based additives should be evaluated because basic residues can protonate dye chromophores and shift absorbance; cationic surfactants in antistatic coatings adjacent to the dyed layer may also extract anionic dye species under humid aging.
