| HS Code | 671690 |
| Product Name | Electronic Ink Curing Agent (Taiyo Ink Curing Agent) Electronic/EL Grade |
| Appearance | Clear to pale yellow liquid |
| Viscosity 25 C | 300–600 mPa·s |
| Specific Gravity 25 C | 1.02–1.06 |
| Acid Value | ≤5 mg KOH/g |
| Amine Value | 200–250 mg KOH/g |
| Color Gardner | ≤2 |
| Flash Point | >100°C |
| Water Content | ≤0.5% |
| Curing Speed Thermal | 30 minutes at 150°C |
| Shelf Life 25 C Sealed | 6 months |
As an accredited Electronic Ink Curing Agent (Taiyo Ink Curing Agent) Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Available in 1 kg amber glass bottle with secure lid, protective label, and tamper-evident seal for safe handling. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with Electronic Ink Curing Agent (Taiyo, Electronic/EL Grade), securely packed and sealed for safe transport. |
| Shipping | This chemical is shipped in sealed, inert HDPE drums with nitrogen padding to prevent contamination and moisture absorption. Transport must avoid high heat, open flames, and incompatible materials. It should be secured upright, with hazard labels and SDS documentation, under cool, dry conditions. International shipments require proper chemical declarations and compliance with IATA/IMDG regulations. |
| Storage | Store in a tightly sealed container in a cool, dry, well-ventilated area, away from direct sunlight, heat, sparks, and incompatible oxidizers. Keep temperature stable between 5–30°C, protected from moisture and contamination. Avoid prolonged exposure to air. Ensure proper labeling and segregation from acids and alkaline materials. |
| Shelf Life | Shelf life is typically six months from manufacture date when stored sealed, cool, dry, and away from direct light. |
Rigid PCB solder mask formulations require a curing agent that maintains crosslink density at the copper interface without generating ionic residues that depress surface insulation resistance after reflow. The Electronic/EL grade curing agent is incorporated at 2.0–4.0 wt% of total wet solder mask mass; for high-contrast white legend inks the additive window is reduced to 1.5–2.5 wt% to limit yellowing during 150 °C forced-air post-cure. A typical production route disperses the material on a ceramic three-roll mill to a Hegman fineness of 5–7 (40–60 µm), then screen prints with 120 T polyester mesh to a wet film thickness of 18–25 µm. Boards are pre-cleaned by microetching to 0.5–1.0 µm copper roughness using sodium persulfate/cupric chloride. UV fixation at 365 nm/385 nm LED requires 800–1,400 mJ/cm²; subsequent thermal cure is 150 °C for 60 min. The cured film is qualified under IPC-SM-840E Class T/H, with adhesion measured by IPC-TM-650 2.4.28.1, surface insulation resistance by IPC-TM-650 2.6.3.3, and chemical resistance under IPC-TM-650 2.3.2. RoHS Directive 2011/65/EU Annex II and REACH Article 33 obligations apply. When ambient relative humidity exceeds 60%, the substrate should be pre-dried at 105 °C for 2 h to avoid microvoiding at the copper interface. Terminal finished product categories include multilayer rigid PCBs, HDI server boards, automotive ECU modules, LED lighting boards, and industrial power supply substrates.
In electroluminescent lamp dielectric pastes printed onto indium-tin-oxide-coated polyethylene terephthalate, the curing agent must maintain high dielectric withstand voltage while limiting acid-catalyzed degradation of barium titanate filler. The addition ratio is 1.2–2.8 wt% of wet dielectric paste; the phosphor encapsulation layer receives a lower dosage of 0.8–1.5 wt% to preserve luminance homogeneity. Screen printing on 125–175 µm ITO-PET uses 200–305 mesh stainless steel or 77 T polyester for the dielectric layer; dry film thickness is controlled at 25–35 µm. UV cure uses 395 nm LED at 400–700 mJ/cm², followed by 120 °C thermal post-cure for 30 min. Dielectric withstand is verified at 300 V AC, 60 Hz according to IEC 60664-1; wet adhesion is tested by ASTM D3359-23; UV resistance is screened under ASTM G154 cycle 1. The material is incompatible with epoxy-amine systems in the same print line; residual amine contamination can initiate premature crosslinking in the storage tank and raise viscosity by more than 15% within 8 h. Finished products include automotive dashboard EL backlights, safety signage, wearable illuminated safety apparel, and keypad backlights for appliances.
Flexible silver conductor overcoat inks for roll-to-roll printed circuits encounter a process conflict between solvent resistance after cure and mechanical flexibility. The Electronic/EL grade curing agent is dosed at 1.0–2.2 wt% of wet formulation. Below 1.0 wt%, incomplete acrylate conversion leaves the surface tacky and sensitive to methyl ethyl ketone rub; above 2.2 wt%, embrittlement appears as microcracking at 10% elongation under ASTM D522 mandrel bend. Production equipment includes roll-to-roll gravure or flexographic lines running at 30–60 m/min, or screen printing with 250–350 mesh stainless steel and 180–250 µm emulsion stencil thickness. Curing on 385 nm UV LED arrays uses 600–1,000 mJ/cm², with optional thermal post-cure at 80–100 °C for 20 min. Adhesion to silver trace and PET/PEN substrate is measured by ASTM D3359-23 crosshatch after 10 cycles of 180° bend at 1 mm radius. Compliance references IPC-FC-234 for flexible circuits, IEC 61249-3-1 for flexible substrates, and RoHS 2011/65/EU. Avoid combination with amine-based additives; even 0.2 wt% of a tertiary amine can reduce pot life from 24 h to 6 h at 25 °C. Finished product categories include membrane switch circuits, smart label antennas, printed battery current collectors, and wearable biometric electrode arrays.
For in-mold electronics processing, the dual-cure balance between partial UV network formation and thermoforming elongation is the primary film-level constraint. The Electronic/EL grade material is dosed at 1.5–3.0 wt% in dielectric pastes and 1.0–2.0 wt% in protective overcoats for screen-printed silver traces. A typical manufacturing sequence prints silver conductors on polycarbonate film using 230 mesh stainless steel, UV pins at 200–350 mJ/cm² with 395 nm LED, overprints the dielectric with 61–120 mesh screen depending on required isolation thickness, then thermoforms at 120–150 °C with 15–25 mm draw depth. After trimming, the formed sheet is insert injection molded with PC/ABS at 260–280 °C melt temperature and 300–500 bar cavity pressure. The cured stack is tested for crosshatch adhesion under ISO 2409, scratch resistance under ISO 1518, and heat-humidity stability at 85 °C / 85% RH for 240 h before functional testing. Compliance includes RoHS 2011/65/EU, REACH SVHC confirmation, and automotive OEM surface performance specifications where applicable. If acrylate conversion before thermoforming exceeds 70% as measured by ATR-FTIR at 810 cm⁻¹, microcracking occurs at draw radii below 5 mm; if conversion is below 50%, the dielectric layer smears during mold closure. Terminal finished parts include overhead console touch panels, steering wheel switch surfaces, home appliance capacitive controls, and seat adjustment modules.
Table 1. Comparative addition windows and key process thresholds for the Electronic/EL grade curing agent.
| Downstream sector | Addition ratio of wet formulation | Critical process window | Primary verification method |
|---|---|---|---|
| Rigid PCB solder mask | 2.0–4.0 wt% | 800–1,400 mJ/cm² at 365/385 nm; 150 °C for 60 min | IPC-TM-650 2.4.28.1 |
| EL lamp dielectric | 1.2–2.8 wt% | 400–700 mJ/cm² at 395 nm; 300 V AC withstand | IEC 60664-1 |
| Flexible silver overcoat | 1.0–2.2 wt% | 600–1,000 mJ/cm² at 385 nm; mandrel bend 1 mm radius | ASTM D522 |
| In-mold electronics dielectric | 1.5–3.0 wt% | Thermoform 120–150 °C; draw depth 15–25 mm | ISO 1518 |
| HMI dielectric spacer | 0.8–2.0 wt% | 500–800 mJ/cm² at 365/395 nm; pencil hardness ≥2H | ASTM D3363-22 |
| E-paper edge seal | 3.0–5.0 wt% | 1,000–2,000 mJ/cm² at 365 nm; 85 °C / 85% RH for 500 h | IEC 62679-3-1 |
Dielectric layer thickness in high-wear human-machine interface stacks controls capacitive response and mechanical durability simultaneously. The curing agent addition is 0.8–2.0 wt% of total wet UV-curable dielectric ink. Screen printing with 200–305 mesh stainless steel delivers a wet film of 20–35 µm, which after 80 °C infrared pre-dry for 5–8 min and UV cure at 365/395 nm with 500–800 mJ/cm² yields a dry spacer of 10–20 µm. Cured film hardness is tested by ASTM D3363-22 pencil hardness to ≥2H; chemical resistance is verified by ASTM D5402-19 methyl ethyl ketone double-rub at ≥50 double rubs; dielectric withstand of the spacer is measured at 500 V DC according to ASTM D257-21. The material should not be processed below 18 °C because rheological recovery after screen shearing becomes irregular and can produce pinholes in the dried film. Compliance includes IEC 61340-5-1 ESD control for control panel assembly and RoHS 2011/65/EU. Terminal products include industrial HMI panels, medical device keypads, point-of-sale terminals, and white goods control membranes.
Because electrophoretic display edge seal materials operate as both a moisture barrier and an ion-migration barrier, the curing agent loading is higher than in conventional solder mask overcoats. The edge seal paste receives 3.0–5.0 wt% of the Electronic/EL grade material; pixel wall inks receive 1.0–2.5 wt% to limit lateral migration of charged pigment particles. Precision dispensing through 27 gauge needles deposits a bead of 0.5–1.0 mm width; pixel wall layers are coated by photolithographic patterning or slot-die coating to 10–30 µm dry thickness. UV cure at 365 nm with 1,000–2,000 mJ/cm² is followed by 80 °C for 30 min dark reaction. Adhesion to ITO/glass and PET is measured by ASTM D3359-23; damp heat exposure at 85 °C / 85% RH for 500 h is accepted when edge seal width change is ≤5% and display contrast shows no visible fade. RoHS 2011/65/EU and REACH Article 33 declarations apply. Published WVTR data for this specific edge seal configuration is limited; production qualification should include cup testing under ASTM F1249 on the actual laminated stack rather than on free films. Do not combine with strong Lewis acid initiators during dispensing because uncontrolled cationic polymerization can raise viscosity above 50 Pa·s within 2 h at 25 °C. Terminal product types are e-readers, electronic shelf labels, smart cards, and ruggedized e-paper signage.
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The Electronic Ink Curing Agent (Taiyo Ink Curing Agent) Electronic/EL Grade is supplied as a liquid reactive hardener for thermal curing of electronic ink binder systems, specifically those used in screen-printed electroluminescent (EL) lamps, membrane switch dielectric layers, and flexible printed circuits. The manufacturer identifies the product by the full designation “Electronic Ink Curing Agent (Taiyo Ink Curing Agent) Electronic/EL Grade”; no shorter alphanumeric code is consistently published in channel-controlled technical documentation. The grade designation is a controlled-category identifier rather than a generic industrial hardener label, indicating that the formulation is maintained for low ionic contamination, reduced cured-film outgassing, and compatibility with indium tin oxide (ITO)-coated polyethylene terephthalate (PET) and high-purity silver flake conductors. In production use, the material is metered as the stoichiometric or catalytic counterpart to Taiyo electronic ink resins; addition levels, cure profiles, and viscosity adjustments are governed by the lot-specific certificate of analysis and safety data sheet. Because the manufacturer releases this grade through channel-controlled technical data sheets, the numerical bands presented below are class-typical electronic/EL hardener values and should be verified against the actual lot documentation before scale-up.
The distinction is not limited to solvent selection or reactive diluent content. The electronic/EL grade is differentiated by controlled hydrolyzable chloride, low alkali-metal catalyst residue, and tighter limits on volatile condensable material. Ionic extractables are checked under IPC-TM-650 2.3.25; electronic/EL procurement specifications commonly reject lots above 1.0 µg NaCl equivalent/cm², whereas general-purpose graphic-arts ink hardeners can exceed 5.0 µg NaCl equivalent/cm² without being out of specification. Surface insulation resistance after cure is evaluated according to IPC-TM-650 2.6.3.3; electronic/EL films on silver interdigitated electrodes are expected to remain above 10⁸ Ω under 85 °C and 85 % RH. Adhesion to ITO-coated PET is assessed by ASTM D3359-17 tape pull after thermal cycling; a minimum class 4B is typical, whereas general-purpose hardeners often fail at 2B because of inadequate wetting of sputtered oxide surfaces. Outgassing is measured by ASTM E595-15 for applications in which EL lamps are sealed inside display housings; total mass loss of the cured film is usually controlled below 0.10 %, and collected volatile condensable material below 0.01 %, while general-purpose hardeners may not carry a condensable volatile specification. The electronic/EL grade also avoids amine-based additives that cause yellowing in phosphor-loaded layers, and it is not interchangeable with Taiyo solder mask curing agents, which may contain fillers and colorants that reduce insulation resistance and increase outgassing.
For the Taiyo Ink Electronic/EL Grade Curing Agent, the supplier’s lot certificate commonly reports the following class-typical control bands. These values are not lot-specific and must be confirmed against the actual certificate of analysis before production. Where the manufacturer’s published data for this specific configuration is limited, the table should be read as procurement acceptance criteria used by printed-electronics converters for this product category.
| Property | Test method | Class-typical control band |
|---|---|---|
| Viscosity at 25 °C | Brookfield LVT, spindle 3, 12 rpm | 0.8–2.0 Pa·s |
| Nonvolatile content | ASTM D2369-20 | 60–80 % |
| Pot life after catalyzation | 20–25 °C, 100 g mass | 4–8 h |
| Recommended cure | Forced-air convection oven | 120–150 °C for 20–30 min |
| Adhesion to ITO/PET | ASTM D3359-17 | ≥4B |
| Surface insulation resistance | IPC-TM-650 2.6.3.3 | ≥10⁸ Ω |
| Ionic extractables | IPC-TM-650 2.3.25 | ≤1.0 µg NaCl eq./cm² |
| Outgassing after cure | ASTM E595-15 | TML ≤0.10 %, CVCM ≤0.01 % |
When the electronic/EL grade hardener is introduced to a cleanroom screen-printing line operating above 60 % relative humidity, the uncured ink film absorbs atmospheric moisture at the surface, leading to amine blush and reduced adhesion after thermal cure. Production-scale systems using flatbed screen printers with 230-mesh stainless steel screens and 65 Shore A squeegees exhibit viscosity drift if open reservoirs are left exposed for more than 30 min. In such conditions the mixed ink should be pre-dried at 40–50 °C for 10–15 min after screen deposition but before final cure, and the printer environment should be maintained below 50 % RH or supplemented with desiccant rotor dehumidification. Failure to control moisture uptake produces microvoids at the dielectric–phosphor interface that are detected as localized luminance dropout in EL lamps after 500 h of cyclic testing. Avoid combination with amine-based additives outside the supplier formulation because premature crosslinking in the open reservoir can raise viscosity above 5 Pa·s within 30 min and make the batch unusable.
In electroluminescent lamp fabrication, the curing agent is first conditioned to 20–25 °C and mixed with the dielectric or phosphor binder at the manufacturer’s specified ratio, typically in the 3–10 phr range for this product class. Mixing should be performed with a planetary mixer or high-shear disperser at 800–1,500 rpm under vacuum to remove entrapped air; vacuum deaeration at -0.08 MPa for 10 min reduces print voids. After screen printing, the wet film is allowed to level for 5–10 min at 23 °C before entering a forced-air convection oven. A class-typical cure profile is 130 °C for 20 min, but the actual cure window may narrow to ±5 °C when the substrate is heat-sensitive PET. Over-cure causes yellowing and embrittlement of dielectric layers; under-cure leaves residual solvent and unreacted amine sites that increase water uptake and reduce surface insulation resistance. For roll-to-roll processing, the oven residence time must be validated with a thermochromic film or in-line thermocouple because PET web temperature lags the setpoint by 10–15 °C at 2 m/min line speed.
Differential scanning calorimetry of the mixed electronic ink reveals an onset of cure at 80–110 °C and a peak exotherm between 130 °C and 150 °C for class-typical epoxy-amine systems. The enthalpy of cure is usually 150–250 J/g when the ratio is adjusted to stoichiometric equivalence; values below 100 J/g after the oven cycle indicate incomplete conversion. The cured film should be checked for residual outgassing by ASTM E595-15; for sealed EL lamp assemblies, total mass loss above 0.10 % and collected volatile condensable material above 0.01 % are common rejection thresholds because condensed monomers degrade luminance and haze. The exothermic peak is sensitive to film thickness; at 50 µm wet thickness the peak shifts to a lower temperature by 5–8 °C due to thermal lag in the PET web. This shift creates a processing conflict on high-speed roll-to-roll lines where the oven residence time is fixed at 15 min or less. In that situation the cure profile must be re-established using a gradient oven rather than a single setpoint; otherwise the center of the film reaches full conversion while the edges remain under-cured.
Rheological response of the mixed ink is designed for screen-printing shear rates between 10 s-1 and 1,000 s-1. At 25 °C the viscosity under 10 s-1 is typically in the 1.0–2.0 Pa·s range, dropping to 0.3–0.6 Pa·s at 1,000 s-1. This shear-thinning behavior permits the ink to pass through 230-mesh apertures without stringing, while the recovery of viscosity after shear prevents slump after the squeegee stroke. The thixotropic index, measured as the ratio of viscosity at 5 s-1 to viscosity at 50 s-1, is normally controlled between 1.5 and 2.5; values above 3.0 correlate with poor leveling and trapped air in the printed film. During production, rotary viscometer checks are made after 15 min of shear to detect batch-to-batch drift. If viscosity after shear exceeds the control band by more than 10 %, the lot is adjusted with an approved thixotropic diluent rather than raw solvent, because solvent dilution lowers the flash point and increases the dry-film shrinkage associated with edge curling on PET substrates.
The cured film is generally compatible with silver flake, phosphor, and barium titanate dielectric layers; however, the hardener should not be used with substrates containing unreacted isocyanate or acid-modified PET films because the amine functionality can react at the interface and lower peel strength. In flip-chip or membrane touch switch assemblies, the cured dielectric must pass ASTM D257-20 volume resistivity of at least 10¹² Ω·cm and surface resistivity of at least 10¹⁰ Ω/sq after damp heat. Use with carbon-conductive inks can be problematic; carbon black surface acidity can adsorb amine species and retard cure at the interface, reducing adhesion and causing voiding.
Regulatory documentation for the electronic/EL grade is maintained through the supplier’s safety data sheet, certificate of compliance, and RoHS/REACH statements. The grade is evaluated for RoHS recast 2011/65/EU and REACH SVHC obligations; halogen content is often tested by EN 14582 against IEC 61249-2-21 limits of 900 ppm chlorine and 900 ppm bromine, with total halogen below 1,500 ppm. Published data for this specific configuration is limited, and lot-level confirmation is required for any customer-specific compliance matrix.
| Compliance domain | Standard or directive | Electronic/EL grade expectation |
|---|---|---|
| Restricted substances | 2011/65/EU, Annex II | Lot-level pass |
| REACH SVHC | Regulation (EC) No 1907/2006 | Declaration by supplier |
| Halogen content | EN 14582, IEC 61249-2-21 | Cl ≤900 ppm, Br ≤900 ppm, total ≤1,500 ppm |
| Surface insulation resistance | IPC-TM-650 2.6.3.3 | ≥10⁸ Ω at 85 °C/85 % RH |
| Ionic contamination | IPC-TM-650 2.3.25 | ≤1.0 µg NaCl eq./cm² |
On a production-scale flatbed screen-printing line, batch-to-batch variance in the curing agent is controlled by lot-specific viscosity adjustment with a thixotropic diluent. If the as-received viscosity falls below 0.6 Pa·s, the ink may slump through 230-mesh screens and short the dielectric layer; if it exceeds 1.8 Pa·s, mesh clogging occurs and edge definition degrades. Therefore the product is not interchangeable with general-purpose hardeners or with Taiyo solder mask curing agents without re-qualification of the full print and cure process. The material should be stored in tightly sealed containers at 5–30 °C and consumed within the manufacturer’s shelf life; repeated freeze-thaw cycling is not recommended because crystallization of the reactive fraction can shift the stoichiometric balance and alter the cured film’s insulation resistance.
