| HS Code | 303711 |
| Product Name | Polarizer Special Dye (Electronic/EL Grade) |
| Manufacturer | Nippon Kayaku Co., Ltd. |
| Product Type | Dichroic dye for polarizer applications |
| Grade | Electronic/EL Grade |
| Color Type | Neutral and dichroic color variants tailored for polarizer performance |
| Dye Class | Organic dichroic dye (typically azo/chromophore-based) |
| Main Function | Provides anisotropic visible-light absorption for polarizing films |
| Purity Level | Electronic grade with ultra-low metal ion and particle contamination |
| Dichroic Property | High dichroic ratio for efficient polarized light absorption |
| Polarization Performance | Capable of high polarization efficiency and suitable transmittance |
| Heat Resistance | Stable under typical LCD/EL manufacturing process temperatures |
| Lightfastness | High resistance to UV/visible light degradation |
| Moisture Resistance | Stable under high-temperature and high-humidity conditions |
| Solubility | Soluble in selected polar organic or aqueous coating systems |
| Physical Form | Powder or granules |
| Storage Condition | Store sealed in a cool, dry, dark place |
As an accredited Polarizer Special Dye Nippon Kayaku Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 1 kg sealed aluminum foil bag under nitrogen, placed inside a labeled cardboard carton with hazard information. |
| Container Loading (20′ FCL) | One 20′ FCL container loaded with Polarizer Special Dye (Nippon Kayaku Electronic/EL Grade), securely packed and protected for shipment. |
| Shipping | This EL-grade polarizer special dye from Nippon Kayaku must be shipped in sealed, light-protected packaging to preserve purity. Maintain controlled temperature and humidity, avoiding extreme heat or moisture. Use expedited, secure freight with proper handling labels and documentation for sensitive electronic-grade chemicals, ensuring safe, contamination-free delivery. |
| Storage | Store in original tightly sealed container in a cool, dry, well-ventilated area away from direct sunlight, heat sources, and open flames. Maintain consistent moderate temperature, ideally 15–25°C, and protect from moisture and humidity. Avoid prolonged exposure to air and incompatible materials. Keep container clearly labeled and inaccessible to unauthorized personnel. Follow manufacturer’s instructions for shelf-life stability. |
| Shelf Life | Shelf life is typically 12 months from manufacture when stored sealed, cool, and away from light. |
In TFT-LCD front polarizer production, Nippon Kayaku electronic/EL grade polarizer special dye is introduced into an aqueous polyvinyl alcohol film line before or during uniaxial stretching, depending on whether the line uses pre-dyed PVA resin or post-stretch exhaustion dyeing. The dyestuff is typically supplied as a low-dust granular material with controlled residual metal ions, and the dye bath is maintained under continuous recirculation with in-line spectrophotometric ratio control. Production-scale PVA film lines draw the film at 3.5:1 to 6.0:1 in the machine direction, with the dye bath held at 30 °C to 55 °C. In the subsequent boric acid crosslinking bath, concentration is commonly controlled between 2.0 wt% and 4.0 wt% at 55 °C to 75 °C, which locks dye orientation and raises film durability. After aqueous rinsing to remove free dye and residual boric acid, the dyed PVA layer is laminated on both sides with triacetyl cellulose or cycloolefin polymer protective film, followed by pressure-sensitive adhesive coating and release liner application. The resulting polarizing film is converted into roll or sheet formats for liquid crystal module producers. Final laminates are tested for luminous transmittance and haze under ASTM D1003-21 and ISO 14782:2021. RoHS compliance is documented under Directive 2011/65/EU Annex II, and REACH SVHC declarations are made under Regulation (EC) No 1907/2006. Because dye-based polarizing film exhibits lower iodine migration and less polarizer bleaching than iodine-PVA systems, it is specified in LCD modules that must survive 60 °C / 90% RH damp-heat cycling. The operational boundary is the washing line: residual anionic dye can plate out on downstream rollers if rinse water conductivity rises above 50 μS/cm and pH drifts above 8.0, so closed-loop conductivity control is required. Published data for the exact Nippon Kayaku dye grade in this wet-stretching equipment configuration is limited, and line qualification is normally performed by measuring single-piece transmittance, dichroic ratio, and crossline color uniformity on a laboratory polarizing film sample. Terminal products include 15.6-inch notebook displays and 23.8-inch desktop monitors using thin-film-transistor active-matrix panels.
OLED cell construction uses a low-reflectance circular polarizer to suppress ambient light reflection from metal cathode layers. The polarizer is fabricated by laminating a dyed PVA polarizing film to a quarter-wave retardation film at an optical axis offset of 45°. The polarizer must maintain a neutral gray appearance across the visible range, because color shift in off-axis viewing is amplified by the emission spectrum of organic light-emitting materials. Electronic/EL grade dye is selected for low residual chloride and low alkali metal content, as mobile ions can contribute to dark spot growth in OLED devices. In roll-to-roll lamination, the dye-based polarizer film is usually 25 μm to 40 μm thick and is handled in an ISO Class 5 cleanroom environment under ISO 14644-1:2015. Polarized light performance is verified with a spectrophotometer using ASTM D1003-21 for transmittance and haze, while reflection color shift is assessed with IEC 62341-5:2018 ambient contrast methods. Terminal products include smartphone OLED displays and wearable devices. A critical boundary is UV-curable pressure-sensitive adhesive processing: the dyed PVA layer requires protection from direct high-energy UV exposure above the dose threshold of the adhesive curing unit, typically below 2 J/cm² in the UVA band, to avoid dichroic ratio loss. Published data for this specific Nippon Kayaku grade in OLED circular polarizer stacks is limited, and qualification is performed by measuring dark spot density, luminance retention, and b* shift after 60 °C / 90% RH storage.
Automotive display polarizer qualification differs from consumer LCD production in that the laminated polarizing film must withstand direct sunload, thermal shock, and low-temperature startup without delamination or color shift. The dye-based polarizer is fabricated with a high-durability PVA formulation and laminated to low-birefringence cycloolefin polymer protective film, which improves heat resistance compared with triacetyl cellulose. In production, the stretched PVA-dye film is dried to a residual moisture content below 1.0 wt% before adhesive lamination; excess moisture can cause bubble formation during autoclave processing. The dye-to-PVA mass ratio is generally held between 0.2 wt% and 0.9 wt% in the final polarizing film to balance transmittance and heat resistance, though published data for this specific electronic/EL grade is limited. The pressure-sensitive adhesive layer is selected from acrylic formulations with a glass transition temperature below −20 °C to maintain bonding at cold start. Center information display polarizers are qualified under ISO 4892-2:2013 xenon-arc exposure, IEC 60068-2-30 damp heat cyclic testing, and IEC 60068-2-14 thermal shock. Typical acceptance criteria include a luminous transmittance loss below 5% and a dichroic ratio reduction below 10% after accelerated aging. The terminal product is a 12.3-inch or 14.5-inch CID polarizer integrated into the dashboard LCD module. The main process conflict is thermal expansion mismatch during hot-press lamination at 80 °C to 100 °C; line operators adjust roll tension and nip pressure to avoid optical mura. Dye migration out of the PVA matrix is controlled by ensuring the protective film has a water-vapor transmission rate below 3 g/m²/day at 40 °C / 90% RH, as measured under ASTM F1249-20.
For coating-type polarizer manufacturing, the dye is dissolved in an aqueous PVA solution and applied by slot-die coating onto a temporary carrier film; the dried layer is peeled, uniaxially stretched, and then laminated to protective films. This route is distinct from wet-stretched PVA film dyeing and allows thinner polarizer layers with lower overall stack thickness. The coating solution viscosity is typically maintained between 2,000 mPa·s and 8,000 mPa·s at 25 °C using PVA with a degree of saponification above 98 mol% and degree of polymerization between 2,400 and 4,000. Slot-die lip gap is set from 50 μm to 150 μm depending on wet thickness target; after drying, the PVA-dye layer is controlled to 20 μm to 30 μm. Uniaxial stretching is performed at 90 °C to 120 °C with draw ratios of 3.0:1 to 5.0:1. Dichroic ratio is measured at 550 nm with polarized UV-visible spectrophotometry, and production targets generally fall between 10:1 and 20:1 for coating-type polarizer film; published data for this specific Nippon Kayaku grade in slot-die coating is limited. Compliance is documented under Directive 2011/65/EU Annex II and IEC 62474 declarable substance reporting. Terminal products include thin polarizer stacks for foldable OLED displays and compact optical sensor assemblies.
| Parameter | Typical Range | Measurement Method |
|---|---|---|
| PVA-dye solution viscosity at 25 °C | 2,000–8,000 mPa·s | rotational viscometer |
| Slot-die lip gap | 50–150 μm | gap gauge |
| Dry PVA-dye layer thickness | 20–30 μm | contact thickness gauge |
| Uniaxial draw ratio | 3.0:1–5.0:1 | line speed ratio |
| Stretch temperature | 90–120 °C | IR pyrometer |
| Dichroic ratio at 550 nm | 10:1–20:1 | polarized UV-visible spectrophotometer |
In machine vision and outdoor instrumentation polarizers, the dye-based film is specified where iodine-based polarizing films fail under prolonged ultraviolet and heat load. The polarizer is produced as a neutral gray sheet with high extinction ratio, often laminated between glass or polycarbonate windows to protect the PVA-dye layer from humidity. Terminal products include polarizing filters for CMOS image sensors, barcode scanners, and outdoor LCD instrumentation. Compliance is typically verified with IEC 62321 methods for restricted substances and ASTM G154-16 for accelerated UV exposure. A known incompatibility is direct bonding to amine-cured silicone or epoxy optical adhesives; free amine groups can deprotonate sulfonic acid dye sites and cause spectral shift. Processing windows are narrow in terms of residual solvent: before lamination, the polarizer must be dried to a solvent content below 0.5 wt% to avoid outgassing during thermal bonding at 120 °C. Published data for this specific outdoor sensor configuration is limited; therefore each stack must be tested for extinction ratio at 550 nm and 630 nm after 1,000 h of UVA-340 exposure.
In active-matrix LCD manufacturing, voltage holding ratio is the proportion of pixel voltage retained between frame refresh cycles. Ionic impurities introduced by the polarizing film can migrate into the liquid crystal cell and reduce VHR, causing image sticking and grayscale nonuniformity. Electronic/EL grade polarizer special dye is therefore specified with low residual sodium, potassium, chloride, and sulfate content; typical production control limits for dyestuff are below 1 ppm for each alkali metal and below 5 ppm for total sulfate, though published data for this specific grade is limited. The dye-to-PVA ratio in the final polarizing film is usually 0.3 wt% to 1.0 wt% for high-VHR LCD polarizers. The dyed PVA polarizer is tested for ion migration by placing a 50 mm × 50 mm sample in contact with deionized water at 80 °C for 24 h and measuring the extract conductivity. Final cells are tested for VHR at 60 °C under a 1 V square wave and 60 Hz using a liquid crystal cell gap of 4.5 μm, with acceptance limits above 99% for high-end LCD modules. The table below lists the typical compliance and test matrix.
| Requirement | Standard or Method | Typical Acceptance |
|---|---|---|
| Restriction of hazardous substances | Directive 2011/65/EU Annex II | Below maximum concentration values |
| REACH SVHC declaration | Regulation (EC) No 1907/2006 | No SVHC above 0.1 wt% |
| Optical haze and transmittance | ASTM D1003-21, ISO 14782:2021 | Luminous transmittance and haze per drawing |
| Voltage holding ratio | IEC 61747-5 or vendor cell test | 99% at 60 °C |
| Damp heat durability | IEC 60068-2-30 | 240 h at 60 °C / 90% RH |
| UV durability | ASTM G154-16 | 1,000 h UVA-340 |
Automotive head-up display polarizers are manufactured with high-polarization-efficiency dye-based PVA film to maintain image visibility when the projected image is reflected off the windshield. The polarizer is cut into small-format rolls and laminated with a high-transmittance pressure-sensitive adhesive and a polycarbonate retardation film. Dye loading in the PVA matrix is controlled between 0.3 wt% and 0.8 wt% to balance extinction ratio and total light transmittance. The critical process step is continuous roll-to-roll lamination at 23 °C to 25 °C and 50% RH to 55% RH to maintain optical axis accuracy within ±0.5°. Terminal products include augmented reality HUD modules in passenger vehicles. Durability is validated by IEC 60068-2-5 solar radiation testing and ISO 4892-2:2013 xenon-arc exposure. The dye-based polarizer must be isolated from direct contact with acidic outgassing from polyurethane foam; otherwise the dichroic dye can protonate and lose absorption. Published data for this specific HUD configuration is limited, and qualification is based on luminance contrast retention and b* shift after 1,000 h at 85 °C / 85% RH.
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Polarizer Special Dye Nippon Kayaku Electronic/EL Grade is introduced as a high-purity dichroic organic colorant for stretched polyvinyl alcohol polarizing films used in liquid crystal display and electroluminescent devices. The model designation is the Electronic/EL Grade qualifier; no separate numerical series code appears in the available public documentation. The designation separates the product from general-purpose dye classes through lower ionic residue, reduced insoluble particle burden, and tightened batch-to-batch optical consistency after PVA alignment. Incoming material is typically screened by solution spectrophotometry, combustion ion chromatography, and inductively coupled plasma mass spectrometry because trace contaminants alter the voltage holding ratio and dark-state leakage of the final polarizer.
Commodity dyes may contain sodium chloride or sodium sulfate at levels above 0.5% by mass because inorganic salts are used as precipitation or grinding aids. For an electronic-grade polarizer dye, residual sodium, chloride, and sulfate are specified at substantially lower limits because mobile ions migrate in the PVA-boric acid crosslinked film under bias and moisture, increasing leakage current and degrading display voltage holding ratio. Nippon Kayaku's Electronic/EL Grade is positioned as a low-ionic-residue product; published data for the exact product is limited, but equivalent high-purity dichroic dye grades are reported with residual metal levels below 100 mg/kg total and total halide below 200 mg/kg after combustion-ion chromatography. Insoluble matter is controlled through liquid particle counting; specifications often require fewer than 100 particles per 10 mL at sizes ≥ 1.0 μm in a 1% aqueous or water-miscible solvent solution. The difference from commodity dyes is therefore measured at the trace-component level rather than by chromophore class alone.
In a sheet polarizer line, the dye is introduced into an aqueous PVA dope or into the swelling/dyeing bath before uniaxial stretching. The dichroic ratio is the primary optical response variable and is defined as parallel absorbance divided by perpendicular absorbance on a drawn film. Production-worthy electronic-grade polarizer dyes generally produce a dichroic ratio above 10 in PVA at a 4× to 6× draw ratio, but the exact value is a function of draw ratio, boric acid concentration, and dye loading. The wet-stretching sequence operates with a swelling bath at 30 °C to 45 °C, a dye bath at 40 °C to 60 °C, and a crosslinking/stretching bath at 50 °C to 65 °C. The dye bath is typically filtered through 0.5 μm absolute polypropylene or polyethersulfone cartridges to remove aggregated dye particles that cause point defects. Published data for this specific Nippon Kayaku configuration is limited; the stated temperature and filtration windows are established for PVA-dye polarizer manufacturing rather than a product-specific optimized recipe.
Because the manufacturer does not publish a complete lot-specific datasheet for the Electronic/EL Grade in open literature, the following framework is used as a qualification guide for electronic-grade polarizer dyes. Exact values must be taken from the vendor certificate of analysis. The framework is presented as representative of the class, not as a certified lot-specific guarantee.
| Parameter | Typical acceptance criterion | Test method |
|---|---|---|
| Purity by HPLC area normalization | ≥ 98.0% | JIS K 0124 or equivalent |
| λmax in methanol | report CoA; compare to vendor reference | JIS K 0115 |
| Dichroic ratio in drawn PVA film | ≥ 10 at 5× draw | Polarized UV-visible spectrophotometry; internal optical bench |
| Moisture content | ≤ 1.0% | Karl Fischer titration; JIS K 0068 |
| Total sodium | ≤ 100 mg/kg | ICP-MS after acid digestion |
| Iron | ≤ 10 mg/kg | ICP-MS after acid digestion |
| Chloride and sulfate | ≤ 200 mg/kg combined | Combustion ion chromatography; JIS K 0127 |
| Insoluble particles ≥ 1.0 μm | ≤ 100 per 10 mL of 1% solution | Light obscuration particle counting |
The framework values above are not substitutes for lot-specific CoA data. The product should be baselined against reference films made on the same stretching equipment to account for machine-specific residence time and shear. Published data for this specific configuration is limited; qualification programs normally include film drawing on a laboratory tensile apparatus with a thermostatic bath and polarized UV-visible measurement at 3 to 5 wavelengths.
Where the Electronic/EL Grade is selected over iodine-based polarizers, the decision is generally driven by thermal and photostability rather than peak polarization efficiency. Iodine-PVA polarizers offer high transmission and polarization degree but degrade at temperatures above 80 °C and high humidity; dye-based polarizers can be specified for automotive display and outdoor-readable instruments where the polarizer must survive 500 h at 85 °C/85% RH without significant depolarization. The Nippon Kayaku Electronic/EL Grade is intended for such dye-type polarizers, although published data for this specific configuration is limited. Compared with commodity photochromic dyes, the grade imposes lower ionic residue and better batch-to-batch λmax stability, which affects color coordinate control in direct-view liquid crystal displays.
| Property | Iodine-PVA | Commodity dye | Nippon Kayaku Electronic/EL Grade |
|---|---|---|---|
| Typical polarization efficiency | ≥ 99.9% | ≤ 99.0% | high; reported values depend on draw ratio |
| Thermal endurance | limited above 80 °C | moderate; varies with chromophore | designed for high-temperature/humidity dye polarizer |
| Ionic impurity control | not applicable | loose | tight; trace metal and halide specifications |
| Moisture sensitivity | high | moderate | lower in final PVA matrix; dye migration controlled by boric acid crosslink |
| Color control | neutral gray | batch-dependent | λmax and batch-to-batch ΔE controlled for display color filtering |
Process differences are similarly concrete. Iodine-PVA polarizers require iodine vapor or aqueous iodine/potassium iodide uptake and are highly sensitive to boric acid concentration; dye-based systems can be processed from aqueous dye solutions with less free-iodine equipment corrosion. The Electronic/EL Grade is intended for aqueous dye-bath processing, but the exact dyeing rate and uptake are controlled by temperature, pH, and co-solvent content. Azo and anthraquinone chromophore classes used in polarizer dyes have different solubility coefficients; the manufacturer technical support specifies the solvent system for a given lot.
Dye uptake into PVA follows a free-volume-controlled diffusion mechanism. For PVA with degree of saponification greater than 99 mol%, the dyeing bath temperature is typically held at 40 °C to 60 °C; higher temperatures increase diffusivity but reduce equilibrium dye uptake due to lower dye-PVA association. The bath pH is usually maintained between 5.5 and 7.5; acidic conditions increase protonation of sulfonate or carboxylate groups on the dye and may reduce solubility, while alkaline conditions can hydrolyze residual acetate groups and shift film retardation. The dichroic ratio after stretching depends on the orientation factor of the PVA chain and the angle between the dye transition dipole and the polymer chain axis. A polarizer dye with a rod-like chromophore and sulfonic acid solubilizing groups aligns more efficiently than a bulky triphenylmethane dye; this is why Electronic/EL Grade products are selected for high dichroic ratio rather than simply high extinction coefficient.
On a manufacturing line with a 1,200 mm wide PVA film and a 20 m/min line speed, residence time in the dye bath may be only 60 s to 180 s. The dye bath concentration is therefore maintained at 0.05 wt% to 0.5 wt% solids, depending on the required single-piece transmittance. Higher dye loading increases the absorbance perpendicular to the draw direction and degrades transmission unless compensated by drawing. When the dye bath is reused, aggregates form by self-association of aromatic chromophores; these aggregates scatter light and appear as dark spot defects. Continuous filtration through 0.5 μm absolute filters and low-foam agitation are necessary. The Electronic/EL Grade is specified to reduce insoluble aggregates in comparison to commodity-grade dyes, but final bath stability must be determined on the specific line because shear history and water quality influence aggregation kinetics.
Optical performance is characterized by single-piece transmittance, degree of polarization, and color coordinates. Total luminous transmittance and haze are measured according to ASTM D1003; color coordinates are determined by JIS Z 8722 with CIE illuminant C and 2° observer. For a dye polarizer film with total luminous transmittance near 40% and polarization efficiency above 99%, the perpendicular transmittance must remain below 0.5% across the visible range. Dye polarizers rarely reach the neutral gray balance of iodine-PVA polarizers; the Electronic/EL Grade is therefore combined with one or more complementary dyes to flatten the wavelength-dependent polarizing efficiency. In multi-dye formulations, the shift of λmax from lot to lot must be below ±2 nm to avoid visible color shift. This lot-to-lot λmax control is one of the parameters that defines Electronic/EL Grade over general-purpose dye.
Electroluminescent displays and organic EL lighting may use circular polarizers that include a quarter-wave retardation layer; in these applications, the linear polarizer's spectral neutralness and high-temperature stability are significant because OLED emitters are broad-band and high current densities heat the display. The dye polarizer must maintain its dichroic alignment after lamination to the retardation film and cover glass. Published data for the specific performance of Nippon Kayaku Electronic/EL Grade in final OLED stacks is limited; qualification should include 500 h to 1,000 h damp-heat and thermal cycling tests at 85 °C/85% RH and −40 °C to 85 °C per individual display manufacturer protocols.
Prior to bath charging, solution preparation starts with cold deionized water or a water/methanol mixture, not by adding water to powder; the dye is dispersed under high shear, then heated to 40 °C to 50 °C to complete dissolution. If the solution is boiled or subjected to high shear above 1,000 s−1, dye aggregates may form. Filtration of the stock solution through a 0.2 μm nylon or PTFE membrane is recommended before dosing the dye bath. The product should not be combined with anionic surfactants at levels above 0.1% because surfactant micelles can solubilize dye aggregates and alter uptake kinetics.
For display component qualification, the product should be evaluated under EU RoHS Directive 2011/65/EU and the REACH SVHC candidate list. Because polarizer dyes are not intentionally added heavy metals, cadmium, lead, mercury, and hexavalent chromium are typically below the RoHS maximum concentration values of 100 mg/kg for cadmium and 1,000 mg/kg for the other substances. However, compliance must be confirmed on each lot because trace metal impurities can enter from raw-material intermediates. The grade should not be assumed to be halogen-free unless specifically declared; residual chloride and sulfate are measured by combustion ion chromatography and reported on the CoA.
Dust handling follows dye-powder precautions: local exhaust ventilation, dust respirator, and protective gloves. Organic dye powders can form combustible dust clouds; the minimum ignition energy and explosion severity should be assessed per EN 14034 or equivalent, but published data for this specific product is limited. Storage should be in sealed containers below 30 °C and below 60% RH. If the material is exposed to humidity above 60%, pre-drying is required to avoid moisture-induced agglomeration. Avoid combination with strong reducing agents or amine-based additives that can reduce the azo bond or alter the dye oxidation state before film drawing.
