E333 (RFE)

Trade NameRFE
Similar NameTris(4-isocyanatophenyl) thiophosphate; Thiophosphoric acid tris(4-isocyanatophenyl ester);  Tris(p-isocyanatophenyl) thiophosphate; Desmodur RFE; tris(p-isocyanatophenyl) thiophosphate
Molecular FormulaC21H12N3O6PS
CAS Number4151-51-3

HARTDUR E333, similar to RFE, is an solventborne adhesive hardener of thiophosphoric-tris-(p-isocyanato-phenyl ester) in ethyl acetate, CAS number 4151-51-3. The light-color E333 is an universal curing agent / crosslinker (isocyanate-type) majorly applied on adhesives for natural and/or synthetic rubber, especially for rubber materials. Benefits with its light-color to colorless and yellowing resistance, E333 is an ideal solution for strict demanding for color, well-suited for grafted cr adhesive, chloroprene rubber adhesive and hydroxyl polyurethane adhesive. E333 can also improve the bonding of plasticizer PVC, oily SBR, top layer/primer leather, silk and etc. E333 can also be added in oil skin treatment agent to get better adhesion reinforcing and oil resistance.

The solvent of E333 is ethyl acetate (EAC), which is in line with the regulation of environment protection in comparison to methylene chloride. Adding E333 into adhesives, it causes the crosslinking reaction and connect substrates, especially for rubber materials.


0.75 kg/aluminum bottle; 20 bottles/carton (15kgs/carton).

180 kg/iron drum.

It can be packaged on demand. Please inquire.      


E333 is a low-toxicity and eco-friendly two-component adhesive. Adding a certain ratio E333 into the adhesive, these mixed adhesives must be used within the pot life (operational period). With different ingredients, the pot life varies accordingly. When missing the operating period, usually delayed by a few hours or one working day, the mixed adhesive will become very thick and viscous quickly. Thus, it is no longer to be used.


Depending on the bonding process and substrates, the most suitable dosage is recommended for a wide range of options.

For curing adhesive of 100 parts by weight (p.b.w.) based on:

Graft-Chloroprene rubber (rubber content approx. 16%): 3%-5% p.b.w. HARTDUR E333

Chloroprene rubber (rubber content approx. 20%): 5%-7% p.b.w. HARTDUR E333

Hydroxyl polyurethane (polyurethane content approx. 15%): 3%-5% p.b.w. HARTDUR E333

Compatibility with solvents

HARTDUR E333 can be diluted with anhydrous and alcohol-free ethyl acetate dichloropropane, trichloroethylene, acetone, methyl ethyl ketone, toluene and other solvents. Adding relatively large proportions of aliphatic hydrocarbons can result in turbidity. However, the solution of aliphatic hydrocarbons in natural rubber(NR) shows good compatibility with HARTDUR E333. Thus, there is no need to add other solvents.

Chemical compositionContains 27% thiophosphoric-tris-(p-isocyanato-phenyl ester) and 73% ethyl acetate
Intrinsic colorAlmost colorless to light-color clear liquid
NCO%7.2 ± 0.2
SolubilitySoluble in various esters, ketones and aromatic solvents
Storage stabilityStore in sealed container. Due to E333 reacts readily with moisture; for best performance it should be kept dry and stored at temperatures between 5℃~32℃. Keep away from moisture, heat and direct sunlight.
 E333 features with high crystallinity, therefore, crystalline deposits may form during transportation and storage at low temperatures.

After the addition of HARTDUR E333, the ready-to-use double-component adhesive should be applied within a period (pot life) which is determined not only by its content of rubber, but also by the other ingredients of the formulation (e.g. resins, antioxidants, solvents, etc.). If the adhesive is not used within this period, it may become increasingly difficult to apply and its viscosity increases rapidly until irreversible gelling ultimately occurs.

Well-suited for being a crosslinking agent of adhesives of Graft-Chloroprene rubber, Chloroprene rubber and Hydroxyl polyurethane.