| HS Code | 167558 |
| Product Name | Sensitizer J&K Scientific ITX |
| Chemical Name | 2-Isopropylthioxanthone |
| Cas Number | 5495-84-1 |
| Molecular Formula | C16H14OS |
| Molecular Weight | 254.35 g/mol |
| Appearance | Light yellow to yellow crystalline solid |
| Purity | ≥98% (HPLC) |
| Melting Point | 66-72 °C |
| Boiling Point | 406.6 °C at 760 mmHg |
| Density | 1.11 g/cm³ at 25 °C |
| Solubility | Soluble in acetone, ethyl acetate, toluene, ethanol; insoluble in water |
| Storage Conditions | Store in a cool, dry, dark place; keep container tightly sealed |
As an accredited Sensitizer J&K Scientific ITX factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Sensitizer J&K Scientific ITX is supplied in a sealed amber glass bottle containing 25 g, with tamper-evident cap and label. |
| Container Loading (20′ FCL) | One 20-foot FCL containing Sensitizer J&K Scientific ITX, securely packed, properly labeled, and documented for safe chemical transport. |
| Shipping | Shipping description: UN 3077, Environmentally Hazardous Substance, Solid, N.O.S. (containing 2-isopropylthioxanthone / ITX), Class 9, Packing Group III. Must be in strong, sealed containers with environmental hazard labelling; for sea transport, add Marine Pollutant mark. Keep away from heat, sunlight, and sources of ignition during shipment. |
| Storage | Store Sensitizer J&K Scientific ITX in a cool, dry, well-ventilated area, away from heat, sparks, and open flames. Keep the container tightly closed and protected from light. Avoid contact with strong oxidizers and moisture. Use appropriate personal protective equipment when handling, and prevent dust accumulation. |
| Shelf Life | Shelf life is typically 2–3 years from manufacture if stored unopened in a cool, dry, dark place. |
In sheetfed offset lithographic UV ink systems formulated for commercial folding carton and publication cover stocks, Sensitizer J&K Scientific ITX (isopropylthioxanthone, CAS 5495-84-1 for 2-isopropylthioxanthone and 83846-86-0 for 4-isopropylthioxanthone) functions as a Type II photoinitiator that abstracts hydrogen from a tertiary amine co-synergist under irradiation, generating radicals for acrylate polymerization. The standard addition bracket is 1.0–2.5 wt% of total varnish weight after solid resin content has been fixed, with the ITX first dissolved into propoxylated glyceryl triacrylate at 45–55 °C before addition of the amine synergist at a 1:1 to 1:2 molar ratio. The premix is dispersed on a high-speed disperser with tip speed of 15–20 m/s, then ground through a three-roll mill or horizontal bead mill until the Hegman gauge reading reaches 7–8 μm. At press viscosity of 12–18 Pa·s measured at 25 °C and Inkometer tack of 8–12, the ink is run on multicolor sheetfed offset presses with interdeck UV lamps rated at 120–200 W/cm and production speeds of 8,000–12,000 sheets/h. Compliance is anchored to ISO 12647-2:2013 clause 4 for tone value and gray balance, REACH Regulation (EC) No 1907/2006 for substance registration, and the EuPIA Guideline on Printing Inks for non-food packaging. Terminal finished products are commercial folding cartons, hardcover book covers, and non-food pressure-sensitive labels where the cured ink film must resist blocking, rub, and high-speed converting.
Liquid photoimageable solder mask formulations for rigid FR-4 and flexible polyimide printed wiring boards use ITX at 0.8–2.5 wt% of total resin solids, typically in combination with ethyl 4-dimethylaminobenzoate or a polymer-bound amine synergist. The production sequence begins with screen printing or curtain coating onto circuitized panels to a dry film thickness of 15–25 μm, followed by pre-bake in a convection oven at 75–80 °C for 20–30 min. UV imaging is carried out through a negative phototool on a LED exposure unit with a 365 nm array delivering 300–600 mJ/cm² to the coating surface; the oxygen-sensitive top layer demands a nitrogen-purged exposure chamber or reduced-oxygen environment below 5% O₂ when maximum resolution below 50 μm line/space is required. Developing is performed in a 1 wt% Na₂CO₃ solution at 30 °C, after which the panel receives a post-cure thermal ramp to 150 °C for 60 min. Compliance requirements include IPC-SM-840E for permanent solder mask qualification, IPC-TM-650 method 2.4.28.1 for adhesion testing, UL 94V-0 flammability classification, and RoHS Directive 2011/65/EU for restricted substances. Terminal products are solder mask defined copper patterns on multilayer PCBs, consumer electronics boards, and flexible circuits where the photocured film must withstand HASL, ENIG, or immersion tin surface finishes.
Processing conflicts arise when the solder mask contains high levels of talc, silica, or barium sulfate fillers because these pigments scatter UV light and reduce photon penetration, making surface tack more likely at the lower addition end of the ITX range. On production lines, under-curing manifests as white residues around via sidewalls after aqueous developing, while overexposure leads to undercutting and reduced sidewall straightness. The kinetic window is therefore controlled by maintaining the photoinitiator-to-co-initiator ratio near 1:2 and by using dual LED heads or a supplementary 385 nm cure step for thick-film variants. Published data for this specific configuration is limited; dedicated line qualification is therefore required. The operational boundary usually necessitates an ITX addition above 0.5 wt% when LED conveyor speed exceeds 3 m/min to avoid residual surface tack.
Flat-panel wood and engineered flooring lines running UV-curable clear or lightly pigmented topcoats incorporate ITX at 0.5–1.5 wt% of total coating formulation, dissolved in the oligomer phase before reactive diluents are added. The coating is applied by roller coater or vacuum coater at 10–20 g/m², then cured under mercury or gallium-doped lamps emitting 400–800 mJ/cm² at conveyor speeds of 8–15 m/min. ITX contributes mainly to surface cure by offsetting oxygen inhibition, which is especially severe on visible-porous wood surfaces because dissolved oxygen is released during irradiation and competes for amine-derived radicals. Through-cure in pigmented white or pastel coatings is reduced because titanium dioxide absorbs strongly in the 365–395 nm region; formulators respond by shifting the ITX ratio toward 1.5 wt% and adding an acylphosphine oxide to generate radicals at greater depth. Adhesion is verified by ASTM D3359-23 tape pull, abrasion resistance by ASTM D4060-19 Taber abraser with CS-17 wheels at 1,000 g load, and household-chemical resistance by DIN 68861-1:2011 classification. The finished product classes are kitchen cabinet fronts, laminate flooring, interior door skins, and flat-pack furniture panels.
Radiation-curable free-radical structural adhesives for display assembly and camera module bonding use ITX at 0.2–1.0 wt% of total resin, generally as a secondary photoinitiator to a phosphine oxide primary initiator, to extend cure response at 365 nm and 385 nm LED wavelengths. The production process is automated precision dispensing of 10–100 μm bond lines onto glass, polycarbonate, or anodized aluminum substrates, followed by pinning with a UV LED spot or line lamp at 2–5 W/cm² for 1–10 s and secondary ambient moisture cure in shadow areas. Mechanical performance is controlled under ISO 4587:2003 or ASTM D1002-10 lap-shear testing, with absolute strength values determined by substrate and primer chemistry rather than photoinitiator level alone. Compliance for electronic device assembly commonly requires IEC 62368-1:2018 as the product safety standard and a flammability rating of UL 94 V-0 or UL 94 V-1 for the cured adhesive film. The finished component types include liquid crystal display frames, smartphone camera modules, and optoelectronic sensor housings.
Solvent-free UV flexographic inks formulated for corona-treated BOPP, PE, and shrink-sleeve films incorporate ITX at 1.0–3.0 wt% of total ink weight, with the higher end used for low-stretch polyolefin substrates that offer fewer bonding sites. The production press is typically a central-impression flexographic line with anilox rolls of 600–1,000 lpi, ceramic doctor chambers, and UV curing at 300–500 mJ/cm², running at 100–200 m/min. The printed ink film remains 1.5–3.0 μm thick, so oxygen inhibition at the ink surface is controlled by elevated ITX loading and an amine synergist at a 1:1 to 1:2 ratio. Standards governing process control are ISO 12647-6:2020 for flexographic printing, while EU product safety for printed packaging follows REACH Regulation (EC) No 1907/2006 and the EuPIA exclusion policy. ITX is not listed in Regulation (EU) No 10/2011 as an authorized plastic monomer or additive, so primary food-contact applications require migration testing below current detection limits and evaluation under national legislation. The 2005 ITX migration incident involving dairy beverage cartons demonstrated why this grade is not automatically suited to direct food-contact printed materials; EU and national authorities issued guidance that pushed formulators toward non-food or indirect-contact applications unless comprehensive migration testing is performed. The finished goods are pressure-sensitive labels, shrink sleeves, and corrugated preprint used in non-food or indirect-contact packaging.
UV-curable powder coatings for MDF profiles and heat-sensitive assembled metal parts use ITX at 0.5–1.5 wt% of the total solid formulation. The coating is compounded in a co-rotating twin-screw extruder with a melt temperature of 90–110 °C and a screw speed of 400–600 rpm, then chill-rolled, flaked, and ground in an ACM mill to a particle size distribution centered near 30–45 μm. Electrostatic application is performed at 60–80 kV, after which the powder enters an infrared or medium-wave IR oven to form a continuous melt film at 100–120 °C over 2–5 min before UV curing at 1,000–2,000 mJ/cm². The main process conflict is melt-flow control: ITX can crystallize from the amorphous melt during cooling, creating haze and reducing intercoat adhesion if the melt temperature drops below 100 °C before the UV lamp. Compliance testing typically references Qualicoat Specification for architectural powder coatings, ASTM D3359-23 for adhesion, ASTM D4060-19 for abrasion, and EN 12206-1:2011 for coated metal substrates used in interior applications. Finished components are pre-assembled office furniture frames, MDF cabinet profiles, and automotive interior trim parts that cannot tolerate high oven temperatures.
Piezo inkjet inks designed for industrial coding, wide-format graphics, and corrugated display printing incorporate ITX at 0.5–1.5 wt% of total ink mass, dissolved in high-boiling monofunctional monomers to maintain viscosity at 8–12 mPa·s at 40–45 °C. Printheads with 10–40 pL drop volume and recirculating ink lines deposit the fluid onto coated paper, polycarbonate, or PET, followed by a first pinning lamp at 385 nm with 100–200 mJ/cm² and a full-cure unit at 500–1,000 mJ/cm². The main limitation is that rutile TiO₂ in white inks absorbs strongly in the 365–395 nm window, reducing through-cure in films thicker than 10 μm; this is addressed by nitrogen inerting at oxygen levels below 3% or by using ITX with a long-wavelength synergist that generates radicals at 405 nm. Compliance for wide-format graphics is assessed through ISO 2409:2020 cross-cut adhesion on the specified substrate, ASTM D3359-23 tape pull, and lightfastness testing under ISO 12040:1997 for printed matter. Terminal printed products are exhibition display panels, point-of-purchase boards, and transport vehicle graphics.
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J&K Scientific ITX is a purified isopropylthioxanthone sensitizer used as a Type II photoinitiator in acrylate and methacrylate ultraviolet-cure formulations. The active compound is identified by CAS 5495-84-1; the molecular formula is C16H14OS and the relative molecular mass is 254.35 g mol-1. The product is supplied as a yellow to pale yellow crystalline powder. The product code does not follow a dimensional model-number convention; batch identity is defined by the lot-specific certificate of analysis and by the supplier article designation. Its absorption maximum in the near-UV occurs between 380 nm and 390 nm, which places it within the emission envelope of medium-pressure mercury arc lamps and 365 nm/385 nm light-emitting diode arrays. Unlike acylphosphine oxide or α-hydroxy ketone initiators, ITX does not undergo unimolecular bond cleavage; it requires a labile hydrogen donor, typically an amine-modified acrylate or ethyl 4-dimethylaminobenzoate, to generate initiating radicals.
Because the sensitizer is used at low concentration and is neutral in the dark, it can be pre-dissolved in the monomer phase without significant thermal polymerization during storage at ambient temperature. This behavior is exploited in ink and coating formulation, where the powder is dissolved in a low-viscosity acrylate before addition to the grinding paste. The dissolution rate is strongly temperature dependent; a rotor-stator mixer at 1,500 rpm and 45 °C jacket temperature typically produces a clear solution, while cold addition to a high-viscosity epoxy acrylate at 25 °C can leave visible crystals that remain undetected until they appear on the doctor blade.
On absorption of a UVA photon, ITX undergoes singlet-to-triplet intersystem crossing with high quantum yield. The triplet thioxanthone abstracts a hydrogen atom from the α-carbon of an amine co-synergist, generating a ketyl radical and an α-aminoalkyl radical. The α-aminoalkyl radical initiates chain growth across acrylate double bonds; the ketyl radical participates in termination and back hydrogen transfer rather than initiation. Consequently, cure speed is not controlled solely by photoinitiator concentration. The amine donor concentration, viscosity, film thickness, and oxygen diffusion rate at the coating surface are equally important. At a wet-film thickness below 10 µm, atmospheric oxygen replenishment is rapid enough to inhibit surface cure unless an amine synergist is present at a concentration of at least 2.0 wt% based on film-forming solids. Formulations using ITX without an amine show persistent surface tack and low crosslink density as measured by solvent rub resistance under ASTM D5402-19 conditions.
LED-curable systems operating at 365 nm, 385 nm, or 395 nm can activate ITX, but the absorbed photon count depends on the exact emitter wavelength and the overlap with the sensitizer’s absorption envelope. At 385 nm, ITX shows useful absorption; at 395 nm, the absorption is lower and cure may become dose-limited. In contrast, acylphosphine oxide photoinitiators have long-wavelength absorption extending beyond 400 nm, making them more efficient in 395 nm LED systems. ITX is therefore co-formulated with an acylphosphine oxide or used at the shorter LED wavelengths. A radiometric dose measured in the 380–400 nm band is not interchangeable with dose measured at 365 nm; the spectral irradiance of the lamp array must be recorded and matched to the sensitizer absorption envelope.
In UV offset inks and overprint varnishes, ITX is commonly introduced at 0.5–2.0 wt% relative to the total curable vehicle, with the lower end used for clear coatings and the upper end for titanium dioxide-pigmented whites and dark pigmented inks. The powder is added during the grind phase rather than the letdown because the high shear of a bead mill or triple-roll mill assists dissolution and prevents recrystallization. Production batches can be made by preparing a 10–20 wt% ITX solution in tripropylene glycol diacrylate at 50–60 °C; the solution remains clear on cooling but may recrystallize if stored below 15 °C. The use of an amine acrylate synergist at 5–10 wt% in the ink vehicle is standard. Curing is normally carried out on sheet-fed or web presses fitted with medium-pressure mercury lamps; line speed and dose are set by a calibrated radiometer in the UVA band. A clear overprint varnish exposed to 150–300 mJ cm⁻² UVA typically reaches full cure when the ratio of ITX to amine is balanced; pigmented ink may require 400–800 mJ cm⁻² depending on pigment absorption and film weight. Full cure is assessed by solvent double-rub resistance under ASTM D5402-19 or by pendulum hardness gain under ISO 1522:2022.
Typical release values for commercial isopropylthioxanthone include an HPLC assay of ≥98.0%, a melting range of 72–78 °C, loss on drying ≤0.5 wt%, and a residual solvent level below the threshold given on the certificate of analysis. The melting range is sensitive to isomer ratio; material enriched in the 2-isopropyl isomer crystallizes at a slightly different point than the mixed 2- and 4-isopropyl grades. Because the product is hydrophobic and sparingly soluble in water, incoming quality control often checks solubility in a defined acrylate monomer at 20 °C rather than by aqueous titration. A common release criterion is that a 10 wt% solution in tripropylene glycol diacrylate is clear after filtration through a 5 µm membrane at 20–25 °C. The powder should be stored in sealed, light-tight containers at ≤30 °C and ≤50% relative humidity to prevent caking and photodegradation. Exposure to direct sunlight promotes yellowing and reduces the absorption envelope, especially at wavelengths below 300 nm.
ITX is often selected as a replacement for benzophenone in white inks because benzophenone’s main absorption lies below 340 nm, where titanium dioxide strongly attenuates light. The thioxanthone chromophore absorbs in the 380–390 nm window, where titania has lower extinction and the mercury lamp still emits useful UVA. This difference reduces the depth-cure penalty in thick white layers. Compared with 2-chlorothioxanthone, ITX has a slightly lower absorbance and lower yellowing in clear films, but it also requires careful attention to solubility because the isopropyl group alters crystal packing. The table below summarizes the principal comparative characteristics. Published data for direct comparisons in complex commercial ink vehicles is limited; the relative cure efficiency should be verified by ladder studies using a laboratory UV conveyor and a calibrated UVA radiometer.
| Characteristic | ITX | Benzophenone | 2-Chlorothioxanthone |
|---|---|---|---|
| Long-wavelength absorption maximum | 380–390 nm | 330–340 nm | 385–395 nm |
| Hydrogen donor requirement | Yes | Yes | Yes |
| Relative cure response in TiO2-pigmented film | Higher than benzophenone; lower than chlorothioxanthone at equal weight | Low | High |
| Yellowing in clear coat at equal use level | Moderate | Low to moderate | Higher |
| Recrystallization tendency in high-melting vehicles | Moderate | Low | Moderate |
Because the comparative data are system-dependent, the table is a relative guide rather than a specification. A statistically valid cure-response comparison requires identical film weight, lamp intensity, substrate, and oxygen level, with conversion measured by acrylate double-bond loss at 810 cm⁻¹ using Fourier-transform infrared spectroscopy. Differences in resin viscosity, pigment loading, and amine synergist concentration can shift the ranking between ITX and chlorothioxanthone, especially in high-solids overprint varnishes.
Residual ITX in poorly cured inks can migrate through paperboard and low-density polyolefin substrates. In the European Union, printed food-contact materials are subject to Regulation (EC) No 1935/2004; plastic-specific materials fall under Regulation (EU) No 10/2011 when applicable. ITX was not included in the Union list of authorised substances in Regulation (EU) No 10/2011 without restriction, and the neat sensitizer does not carry a universal food-contact approval. Converters must evaluate the printed article by migration testing, for example using EN 1186-15:2002 or subsequent equivalent methods, and demonstrate that the specific migration limit or detection limit applied to the packaged food is met. Low crosslink density, incomplete surface cure, and excessive photoinitiator addition above the recommended range increase the risk of extractable residues. In practice, the use of a barrier varnish, post-cure storage at controlled temperature, and removal of residual amine synergist are required to reduce migration below the analytical detection threshold. Analytical determination of residual ITX is usually performed by high-performance liquid chromatography with diode-array detection at 382 nm after extraction; the limit of quantification must be below the applicable migration limit. The user is responsible for verifying regulatory compliance for the final article; supplier data should not be treated as a migration clearance.
