Covestro Desmodur N3400 HDI dimer ultra-low viscosity high-solid low-viscosity formula uses anti-yellowing curing agent

Product Introduction
Aliphatic polyisocyanate (HDI uretdione);
Used as a curing agent component for weather-resistant polyurethane coating systems




Measurement unit



21.8 ± 0.7


M105 -ISO 11909


175 ± 75

mPa ·s

M014 -ISO 3219/A.3

Color value(Hazen)

≤ 80

M017 -EN1557


about 1.14



*This data is general information and is not part of the product manual.

Desmodur® N3400 is mainly used as a reactive diluent or curing agent for weather-resistant two-component polyurethane coatings, and as a resin for one-component moisture-curing polyurethane coatings. Desmodur® N3400 is usually mixed with other aliphatic polyisocyanates in two-component systems, such as Desmodur® N3200, ultra N3300, N3600 and Z4470. An ideal co-reactant is a hydroxyl polyacrylate. In one-component polyurethane systems, Desmodur® N3400 can be used as a single resin or mixed with other polyisocyanates, such as Desmodur® N3200 and ultra N3300. Due to its low viscosity, Desmodur® N3400 can also be used as a hardener in waterborne two-component polyurethane coatings.

Generally, Desmodur® N3400 can be mixed with the following products: aliphatic polyisocyanate such as Desmodur® N100, N75, N3200, ultra N3300, N3600 and Z4470; aromatic polyisocyanate such as Desmodur® L/ ultra L, HL and IL/ ultra IL; hydroxyl polyester such as Desmophen® 670; hydroxyl acrylate such as Desmophen® A series products. However, it is advisable to perform a compatibility test before each mixed use. Desmodur® N3400 is not very compatible with branched hydroxylated polyesters such as Desmophen® 651.

Desmodur® N3400 can be diluted by solvents such as esters, ketones and aromatic hydrocarbons, such as ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, acetone, methyl ethyl ketone, methyl Isobutyl ketone, cyclohexanone, toluene, xylene, No. 100 mineral spirits and their mixtures. Generally, it has good compatibility with the various solvents listed, but the storage stability of its diluted solution still needs to be tested. Polyurethane grade solvents should be used (less than 0.05% water and should not contain reactive groups such as hydroxyl or amino groups in the solvent). Aliphatic hydrocarbons are not suitable as solvents.
Desmodur® N3400 cannot be diluted below 40% solids. Long-term storage of solutions with low resin content may cause turbidity and precipitation.

– Store in original Covestro airtight container.
– Recommended storage temperature: 0-30°C.
– Protect from moisture, heat and foreign substances.
General Information: This product is sensitive to moisture. Storage at high temperature (greater than or equal to 30°C) will darken the color and increase the viscosity of the product.

Storage Time
Covestro declares that, provided that the product has been stored in full compliance with the requirements set out in the “Storage” clause above and has been properly handled, the product has been shipped from the date of shipment stated on the transport document Compliance with the specifications or characteristic values ​​stated in the above clause “Specification or characteristic values” (as applicable) within 6 months. If the product exceeds the above-mentioned 6-month period, it does not mean that it no longer meets the set values ​​in the specifications or characteristic values. However, Covestro recommends that products older than 6 months from the shipping date be tested before use to confirm that they still comply with the values ​​set in the specifications or characteristic values. Covestro makes no promises and accepts no responsibility or liability for non-conformity to specifications or set values ​​in characteristic values ​​for products older than 6 months from the date of shipment.