| HS Code | 738478 |
| Product Name | Thermosensitive Dye (Non-Electronic/EL Grade) Domestic General Grade |
| Product Type | Thermochromic dye |
| Grade Classification | Domestic general grade (non-electronic/EL) |
| Physical Form | Fine microencapsulated powder |
| Appearance | Light-colored or near-white powder at room temperature |
| Activation Temperature | Typically 30°C to 70°C depending on formulation |
| Transition Type | Reversible thermochromic color change |
| Cold State Color | Visible colored state below activation temperature |
| Hot State Color | Transparent or colorless above activation temperature |
| Solubility | Insoluble in water; dispersible in organic resins and solvents |
| Particle Size Range | Approximately 1 to 10 micrometers |
| Thermal Stability | Stable for short periods up to about 200°C when encapsulated |
| Lightfastness | Moderate; prolonged ultraviolet exposure may reduce performance |
| Cycle Life | Capable of repeated heating and cooling cycles with gradual fatigue |
| Moisture Sensitivity | Sensitive to humidity in unencapsulated form |
| Toxicity | Low toxicity for general domestic handling; avoid ingestion and inhalation |
| Storage Conditions | Store in a cool, dry, dark environment below 25°C |
| Shelf Life | Approximately 12 months under recommended storage conditions |
| Intended Use Level | Domestic general-purpose color-changing applications |
As an accredited Thermosensitive Dye (Non-Electronic/EL Grade) Domestic General Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in sealed, moisture-proof 25 kg fiber drums with inner lining, labeled for domestic general-grade thermosensitive dye use. |
| Container Loading (20′ FCL) | Loading a 20′ FCL container with domestic general grade thermosensitive dye (non-electronic/EL grade), securely packed and stowed for safe transit. |
| Shipping | Shipped via domestic ground freight in sealed, light-resistant containers to avoid contamination and moisture. Temperature-sensitive, so avoid prolonged heat exposure during transit. Includes Safety Data Sheet and proper labeling. Non-hazardous for standard handling under general domestic transport regulations. Ensure upright positioning and dry storage upon delivery. |
| Storage | Store in a tightly sealed, opaque container in a cool, dry, well-ventilated area, away from direct sunlight, heat sources, and moisture. Ideal temperature: 5–25°C (41–77°F). Avoid freezing and prolonged exposure to high temperatures, which degrade thermosensitive properties. Keep separate from food, oxidizers, and incompatible materials. Use within manufacturer’s stated shelf life. |
| Shelf Life | Shelf life is typically 24 months when stored unopened in a cool, dry, dark place at room temperature, away from heat sources. |
In thermal registering paper production, the domestic general grade leuco dye is wet-milled as an aqueous dispersion before incorporation into a PVA/styrene-butadiene binder system. The dye addition occupies 3.5–6.5 wt% of total dry coating solids, while the developer-to-dye mass ratio is maintained between 1.5:1 and 3.0:1. A sensitizer selected for a differential scanning calorimetry endotherm between 60 °C and 90 °C is added at 0.5–3.0 wt%. Dispersion proceeds in a horizontal bead mill filled with 0.4–0.8 mm zirconia beads at a tip speed of 8–12 m/s until the millbase particle diameter D90 falls below 1.5 µm. The coating color viscosity is adjusted to 800–1500 mPa·s as measured by Brookfield RVT spindle 4 at 50 rpm; viscosity drift greater than 10% during a production run has been associated with microcapsule agglomeration and non-uniform static image density. Compliance for indirect food-contact uses relies on FDA 21 CFR 176.170, while REACH Regulation (EC) No 1907/2006 governs the EU market. EU 2016/2235 applies when bisphenol A-based developers are present, with a residual BPA concentration below 0.02% by weight in the finished paper.
The coating is applied on blade or curtain coaters at a line speed of 300–900 m/min to a dry coat weight of 4.5–8.0 g/m² per side. Dryer zones are set at 90–120 °C so that the web surface remains below the thermal response onset of the dye matrix; residual moisture is controlled between 4.5% and 6.5%. Static image density is evaluated using a MacBeth RD-918 densitometer after conditioning for 24 h at 23 °C and 50% RH. The domestic general grade may exhibit lower static sensitivity than electronic-grade material, so developer-to-dye ratio adjustments within the stated range are made based on incoming dye absorption spectra and thermal response curves. Published data for this specific configuration is limited for ultra-high-speed thermal printers, and qualification on target printer hardware remains necessary. Terminal finished product types include point-of-sale receipt rolls, parcel logistics labels, parking tickets, medical chart paper, and lottery ticket stock.
| Coating component | Mass fraction on dry solids | Process function | Relevant control standard |
|---|---|---|---|
| Leuco dye dispersion | 3.5–6.5 wt% | color former | In-house HPLC purity ≥ 98.0% |
| Developer | 8–15 wt% | proton donor | EU 2016/2235 BPA < 0.02% |
| Sensitizer | 0.5–3.0 wt% | lower thermal threshold | DSC endotherm 60–90 °C |
| Binder | 10–25 wt% | anchorage and gloss | ISO 3251 |
| Filler | 40–60 wt% | printability and blocking resistance | ISO 8791-4 |
The domestic general grade is compounded into solventborne or UV-curable clear screen bases at 5–15 wt% of total ink weight for screen-printed thermochromic packaging. Viscosity is adjusted to 1500–3500 mPa·s at 25 °C, and the ink is printed through polyester monofilament meshes from 90 threads/cm to 140 threads/cm with a stencil thickness of 20–40 µm. Curing uses long-wavelength infrared dryers with substrate surface temperatures held below 130 °C or UV units delivering 120–200 mJ/cm²; higher surface temperatures induce irreversible loss of the reversible color transition. The production process requires corona-pretreated polypropylene or polyethylene terephthalate surfaces at 38–42 mN/m dyne level. Addition levels below 5 wt% reduce color contrast to less than 2 ΔE*ab units on a CIELAB difference measured after cooling, while levels above 15 wt% cause screen mesh clogging and ink transfer defects. Compliance for printed substrates intended for children is assessed through EN 71-3 migration limits and ASTM F963-17, while the EU market requires REACH Regulation (EC) No 1907/2006 documentation. Lightfastness is measured by ISO 105-B02, with the general grade commonly showing visible fading after 50–100 h xenon arc exposure; UV absorber addition at 1–2 wt% is therefore specified for packages exposed to retail lighting. Terminal finished product types include thermochromic beverage can wrappers, promotional coasters, security box closures, and interactive packaging for cosmetics.
PVC plastisol compounding for color-change consumer goods uses the domestic general grade at 2–8 phr relative to paste resin. The pigment is pre-dispersed in a selected plasticizer before addition to the main plastisol to avoid high-shear agglomerates. Mixing occurs in planetary mixers at 500–1500 rpm for 10–20 min, followed by vacuum degassing at -0.095 MPa until air bubbles are removed. The plastisol viscosity is controlled at 1500–4500 mPa·s depending on dip molding or rotational slush molding requirements. Fusion in tunnel ovens is set at 180–200 °C for 2–6 min. The critical processing boundary is the microcapsule wall rupture limit; oven temperatures above 210 °C produce irreversible leakage of the leuco dye-developer-solvent system and permanent background staining on the finished part. When lower plasticizer solvation is required, a shorter high-temperature residence at 195 °C for 3 min is preferred over a longer low-temperature cure, because the thermal dose rather than peak temperature alone controls wall integrity. Compliance includes EN 71-3 for elemental migration, CPSIA Section 108 for phthalate restrictions, REACH Annex XVII entries 51 and 52, and FDA 21 CFR 177.1210 for gasket and closure uses where applicable. Terminal finished product types consist of reversible color-change baby feeding spoons, beverage cups, bath toys, stress-relief novelty items, and promotional toys.
On production lines, batch-to-batch variance in domestic general grade wall thickness has been observed as differences in onset of irreversible color loss during oven residence trials. Incoming QC therefore should include thermal shock testing of a pressed film at 210 °C for 10 min; a color shift remaining reversible after cooling indicates adequate wall integrity for plastisol processing. Since published data for this specific configuration is limited, process window mapping at 180 °C, 195 °C, and 210 °C is recommended before serial production.
Melt-processable thermochromic masterbatch prepared from the domestic general grade is let down into polypropylene or polyethylene at 2–5 wt%. The masterbatch is produced on a twin-screw extruder with an L/D ratio of 40:1, screw speed 300–500 rpm, temperature profile from 170 °C to 200 °C, and die pressure 6–12 MPa. The base resin should have a melt flow rate between 10–30 g/10 min as determined by ISO 1133-1:2022; higher-viscosity grades increase shear heating and threaten capsule rupture. Injection molding barrel settings are held at 190–215 °C, with mold temperature at 25–40 °C. The lower addition boundary is driven by color contrast: below 2 wt%, the chroma shift after activation is generally below acceptable threshold, especially in thin-walled parts. The upper practical boundary is 8 wt%, beyond which die swell and screw slippage may appear. Pre-drying is mandatory at 80 °C for 2–4 h when ambient relative humidity exceeds 60%, because residual moisture leads to capsule hydrolysis and premature failure during melt processing. Compliance is verified through EN 71-3 for toy safety, FDA 21 CFR 177.1520 for polyolefin food-contact articles, and REACH. Mechanical properties after masterbatch addition are tested by ASTM D638-14 tensile specimens and ISO 179-1/1eU impact bars; reductions not exceeding 10% relative to unfilled resin are typical when the addition is kept below 5 wt%. Terminal finished product types include reusable thermochromic cups, bottle closures, cutlery handles, and automotive interior trim inserts where color shift indicates temperature exposure.
Textile printing lines incorporate the domestic general grade into water-based acrylic binder systems at 3–10 wt% on paste weight. The pigment paste is printed through flatbed or rotary screens with mesh counts from 43 threads/cm to 80 threads/cm, using a stencil thickness of 100–200 µm. Curing is performed in forced-air dryers at 150–170 °C for 120–180 s; the fabric surface must reach the crosslinking temperature of the binder without exceeding 180 °C, because the microcapsules begin to lose thermal reversibility at higher temperatures. Addition below 3 wt% does not produce sufficient visual contrast on dark cotton substrates, whereas addition above 10 wt% increases paste tack and reduces crockfastness. Wash fastness is measured by ISO 105-C06, crockfastness by ISO 105-X12, and lightfastness by ISO 105-B02. For garments intended for children, EN 71-3 and REACH documentation are mandatory; textile formulations are additionally screened against ZDHC Manufacturing Restricted Substances List requirements in global supply chains. Terminal finished product types include athletic garment logos with thermal response, temperature-sensitive promotional T-shirts, and infant sleepwear indicators where a color transition identifies body surface temperature increase.
Anti-counterfeit lacquer systems for gravure and flexo printing use the domestic general grade at 4–15 wt% of total lacquer solids. The process uses gravure cylinders engraved at 60–80 lines/cm with chambered doctor blades, drying at 60–80 °C, and web tension of 50–150 N/m. The liquid phase is restricted to aliphatic hydrocarbons, ethanol, ethyl acetate, and limited quantities of propylene glycol methyl ether. Ketones and high-polarity polyester solvents are avoided because they induce swelling of the microcapsule shell and cause premature dye bleed; ester content is held below 5% of the total solvent blend. Viscosity is controlled at 18–25 s for a DIN cup 4 at 20 °C. The lacquer is applied as a spot coating over tamper-evident seals; when the coating is rubbed or warmed above the specified activation temperature, the color shift creates a verification signal that cannot be reproduced by standard copying. Compliance is determined by ASTM D4060 for abrasion resistance, ISO 105-B02 for lightfastness, REACH, and EN 71-3 where printed materials reach consumer hands. Terminal finished product types include tax stamps, product authentication labels, security closure films, and tamper-evident voucher coatings.
Batch acceptance inspection for the domestic general grade should include a solvent-resistance screen in the intended solvent blend at 25 °C for 24 h; visible color bleed or loss of thermal reversibility after the immersion period indicates a non-conforming lot for anti-counterfeit coating. Since published data for this specific configuration is limited, lacquer formulators should qualify each incoming lot by pilot gravure trials before production release.
Competitive Thermosensitive Dye (Non-Electronic/EL Grade) Domestic General Grade prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615365186327 or mail to admin@ascent-chem.com.
We will respond to you as soon as possible.
Tel: +8615365186327
Email: admin@ascent-chem.com
Flexible payment, competitive price, premium service - Inquire now!
Thermosensitive Dye (Non-Electronic/EL Grade) Domestic General Grade, model TC-DG-301, is a fluoran-type leuco colour former supplied as a free-flowing powder for thermal imaging layers, solvent-borne thermochromic inks, and polymer masterbatches. The term non-electronic/EL grade specifies that the material has not been refined to satisfy the ionic-purity and charge-trapping requirements of electroluminescent or organic electronic devices; total mobile-ion content is controlled but not guaranteed below 10 mg/kg as would be typical for device-grade fluorans. Manufacturer release limits include an HPLC assay of ≥ 98.0%, a melting endotherm between 176 °C and 181 °C by ISO 11357-1:2016, and a moisture content of ≤ 0.5 wt% by ASTM E203-16. The domestic general grade is supplied under GB/T 2828.1 general inspection level II and is intended for non-electronic colour-forming applications in which cost-sensitive batch production is used.
Physical release data for representative lots indicate a laser-diffraction median particle size D50 of 3.0–5.5 µm and D90 ≤ 12 µm when measured by ISO 13320:2020. Residual chloride, sodium, and iron are controlled to ≤ 100 mg/kg, ≤ 50 mg/kg, and ≤ 20 mg/kg respectively. These upper limits are higher than those of export-oriented or electronic-grade fluorans, where sodium plus potassium is commonly specified below 10 mg/kg. The difference is functionally insignificant for thermal paper and thermochromic ink but becomes critical in printed organic field-effect transistors or electroluminescent phosphor binders where ion migration degrades threshold voltage stability.
The product is released with verification of selected heavy-metal migrated content by ISO 3856-1 and ISO 787-9 for aqueous extract pH. Compliance with RoHS Directive 2011/65/EU Annex II is documented at the homogeneous-material level; lead, cadmium, mercury, and hexavalent chromium are each below 10 mg/kg. The product does not carry an unconditional food-contact declaration. When used in food-contact thermal paper or packaging inks, the finished article must be evaluated under Regulation (EU) No 10/2011 and FDA 21 CFR 176.170, because the dye may migrate if the overcoat layer is cracked or if the coating is not fully crosslinked. A residual solvent test by GC headspace after drying should target toluene and methyl ethyl ketone below 5 mg/m² for safety-sensitive printed matter.
| Property | Method | Release value |
|---|---|---|
| Appearance | Visual under D65 light | Off-white to pale-grey powder |
| Assay | HPLC area normalisation | ≥ 98.0% |
| Melting endotherm | ISO 11357-1:2016 | 176–181 °C |
| Particle size D50 | ISO 13320:2020 | 3.0–5.5 µm |
| Particle size D90 | ISO 13320:2020 | ≤ 12 µm |
| Moisture | ASTM E203-16 | ≤ 0.5 wt% |
| Chloride | Ion chromatography | ≤ 100 mg/kg |
| Sodium | Ion chromatography | ≤ 50 mg/kg |
| Iron | ICP-OES | ≤ 20 mg/kg |
| RoHS-restricted metals | Directive 2011/65/EU Annex II | Each ≤ 10 mg/kg |
On production thermal paper coating lines, TC-DG-301 is introduced as an aqueous dispersion rather than dry powder to control particle size stability and avoid dust exposure. A high-solids pre-dispersion containing 10–20 wt% dye, anionic surfactant, and deionised water is milled in a horizontal bead mill with yttria-stabilised zirconia beads of 0.6–0.8 mm diameter. Tip speed is maintained at 8–12 m/s, jacket temperature at 10–15 °C, and mill discharge temperature below 35 °C. Overheating in the mill promotes dye recrystallisation and reduces image density. Final dispersion viscosity is 80–150 mPa·s at 25 °C and 100 s-1. The dye dispersion is then blended with a developer dispersion, typically a bisphenol-free sulfonyl phenol or urea-urethane developer, and a sensitizer such as diphenyl sulfone. Application is made by curtain coater or rod coater at a dry coat weight of 3.5–5.5 g/m². The pH of the final coating colour is maintained at 6.5–7.5; acidic pH below 5.0 causes premature dye-developer interaction in the wet state, while alkaline pH above 8.5 hydrolyses the dye. Image density in this configuration depends strongly on chloride residue: when chloride exceeds 120 mg/kg, competitive salt formation with the developer can reduce image density by 0.10–0.15 density units.
Solvent-borne thermochromic inks require the leuco dye, developer, and solvent to be matched by polarity. For TC-DG-301, a workable solvent blend is toluene, methyl ethyl ketone, and ethyl acetate at a weight ratio of 40:35:25. The dye is dissolved under high-shear agitation at 35–40 °C; dissolution above 50 °C accelerates auto-oxidation and lowers final colour yield. The dye concentration should remain at or below 8 wt% of total liquid formulation because precipitation occurs at lower temperatures when concentration exceeds this threshold. Screen-printing formulations are adjusted with polyvinyl butyral or polyamide resin to a viscosity of 100–250 mPa·s at 25 °C and 10 s-1. Solubility of TC-DG-301 at 25 °C is approximately 40 g/L in toluene, 25 g/L in methyl ethyl ketone, and 18 g/L in ethyl acetate. The powder is practically insoluble in water and aliphatic hydrocarbons. Solubility in ethanol is below 5 g/L, which limits the use of single-solvent alcohol-based flexo inks; a co-solvent is required to prevent precipitation on anilox rolls. The addition of amine-based adhesion promoters or amine-terminated wetting agents is contraindicated; primary and secondary amines form competing complexes with the developer and suppress the colour-forming reaction. If UV exposure during indoor display exceeds 500 lx for more than 72 h, 0.1–0.3 wt% of a hindered amine light stabiliser or a UV absorber is added to the clear overprint varnish rather than to the colour layer.
In polymer masterbatch compounding, TC-DG-301 is pre-dispersed into a low-melting carrier such as ethylene-vinyl acetate or low-density polyethylene. Compounding on a co-rotating twin-screw extruder with L/D 40:1 and screw speed 250–400 rpm is preferred. Barrel zones are set from 110 °C at the feed throat to 150 °C at the die, with melt temperature limited to 165 °C. Above this temperature, irreversible oxidation of the fluoran ring is observed as a shift of the colour-activation threshold by more than 5 °C and a decline in reverse colour contrast. Letdown ratios of 3–5 wt% dye in the final injection-moulding compound are typical for tamper-evident closures and temperature-indicating appliance parts. Moulding residence time should be kept below 4 min at melt temperature; longer residence times reduce contrast in polypropylene matrices due to migration of the dye away from the developer phase.
Unlike conventional solvent dyes or pigments, TC-DG-301 does not exhibit an intense visible colour in its unactivated solid state. Colour development requires proton transfer from an acidic developer; therefore standalone use in lithographic ink without developer is not effective. This distinguishes it from permanent acid dyes and from microencapsulated thermochromic slurries in which the full three-component system is already supplied as a finished slurry. In the domestic general grade, the dye is supplied as a single colour former, allowing formulators to select developer and solvent independently to tune activation temperature and solvent resistance.
Temperature-indicator labels and irreversible thermal verification strips can use TC-DG-301 when the application does not require the low ionic mobility of organic electronic materials. In an encapsulated three-component system, the visible change from pale to deep blue is triggered at a developer-dependent activation temperature, commonly 60–70 °C for a bisphenol-F developer at a dye-to-developer-to-solvent weight ratio of 1:3:5. The domestic grade may show wider batch-to-batch variation in residual chloride and D90 than imported electronic-grade fluorans; screen-printed label reflectance density varies by ±0.08 unless the dye is pre-sieved through a 45 µm mesh and the dispersion is filtered through a 25 µm cartridge before printing. Pre-drying of label stock is required at relative humidity above 60%, because surface moisture reduces adhesion of the leuco dye-developer layer and causes non-uniform colour development on rotary letterpress lines.
| Parameter | TC-DG-301 Domestic General Grade | Electronic-grade fluoran | Export-oriented general grade |
|---|---|---|---|
| Assay | ≥ 98.0% | ≥ 99.5% | ≥ 98.5% |
| Total sodium + potassium | ≤ 100 mg/kg | ≤ 10 mg/kg | ≤ 50 mg/kg |
| Chloride | ≤ 100 mg/kg | ≤ 5 mg/kg | ≤ 80 mg/kg |
| D50 | 3.0–5.5 µm | 2.0–3.5 µm | 4.0–7.0 µm |
| D90 | ≤ 12 µm | ≤ 8 µm | ≤ 15 µm |
| Primary use boundary | Thermal paper, thermochromic ink, masterbatch | OLED/EL host, organic transistor test vehicles | Thermal paper, export ink formulations |
The designation EL grade refers to a purification category rather than a standardised industry specification. In comparison with TC-DG-301, EL-grade fluorans are subjected to repeated recrystallisation and ion-exchange treatment to reduce sodium, potassium, and chloride to low single-digit mg/kg levels. This purification lowers the concentration of charge-trapping sites and improves the stability of electroluminescent phosphor-dye blends. Domestic general grade retains higher ionic residuals and broader particle-size distribution, but the colour-forming function is equivalent when the developer system is properly selected.
Storage is specified at 25 °C or below and relative humidity ≤ 60% in sealed, aluminium-lined fibre drums. Shelf life from date of manufacture is 12 months when stored under these conditions. The product is incompatible with strong oxidisers, strong mineral acids, and heavy-metal salts. Dry blending with zinc chloride or ferric chloride developers initiates immediate solid-state colour formation and must be avoided. Vacuum drying at 40 °C for 8 h is recommended if headspace moisture exceeds 0.5 wt%. For export applications, additional documentation under REACH and national chemical inventories may be required; the absence of such documentation is a regulatory compliance matter and does not indicate a failure of the domestic general grade specification.
