Hardener (Similar to RFE)/ TPUA-E33D

Key feature

● Similar to RFE

● NCO: 7.2 ± 0.2% by weight

● Appearance: clear yellow to brownish liquid

● Enhance the bonding strength of adhesive

● Increase the heat resistance of adhesive


The light-color TPUA-E33D (similar to RFE) is an established, universal curing agent for adhesive based on hydroxyl polyurethane, natural and synthetic rubber. TPUA-E33D can be used instead of TPUA-13-F25G . RFE is even more satisfactory from the aspect of industrial hygiene.


After the addition of TPUA-E33D, 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.

Typical Properties

Chemical composition

Contains 27% thiophosphoric-tris-(p-isocyanato-phenyl ester) and 73% ethyl acetate


Clear yellow to brownish liquid

NCO content, % by weight



Soluble in acetone, toluene and methyl ethyl ketone and aromatic solvents

Storage stability

Reacts readily with moisture; for the best performance it should be kept dry and stored at temperatures between 5oC and 32oC

Compatibility With Solvents

TPUA-E33D can be diluted with anhydrous and alcohol-free ethyl acetate dichloropropane, trichloroethylene, acetone, methyl ethyl ketone, toluene, and other solvents. The addition of relatively large proportions of aliphatic hydrocarbons can cause turbidity; but the solution of natural rubber in aliphatic hydrocarbons shows good compatibility with TPUA-E33D, in the absence of other solvents.


TPUA-E33D shows good bonding strength in PVC with much plasticizer, SBR with plenty of oil, coating leather, silk and so on.

Suggested Additions

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. TPUA-E33D

Chloroprene rubber
(Rubber content approx. 20%)

5-7 p.b.w. TPUA-E33D

Hydroxyl polyurethane
(Rubber content approx. 15%)

3-5 p.b.w. TPUA-E33D


A. each 0.75 kg in an aluminum bottle.
    each 20 bottles in standard carton.

B. each 180 kg in each iron drum.


Notice: These values are based on the test of our present laboratory test specimens.