Description

Desmodur BL 3175 SN is a blocked, aliphatic polyisocyanate based on HDI. In combination with Desmophen grades, it formulates lightfast, one-component polyurethane stoving coatings; it can also be used as an additive in conventional stoving systems to improve flexibility and adhesion. It is supplied at approximately 75% concentration in solvent naphtha 100. Unlike the unblocked, two-component Covestro hardeners Desmodur IL 1451 BA and Desmodur HL BA processed elsewhere in this session, Desmodur BL 3175 SN is a blocked isocyanate for single-component stoving systems — a different chemistry and application category (see DATA FLAG).

Product Data

Solubility / thinnability

Generally speaking, Desmodur® ultra IL 1351 BA has good thinnability with esters such as ethyl acetate, butyl acetate and 1-methoxypropylacetate-2 and with aromatic hydrocarbons such as toluene, xylene, Solvesso® 100 and Shellsol® A. However, the solutions formed must be tested for their storage stability. The product cannot be thinned with white spirit. Alcohols cannot be used as they react with Desmodur® ultra IL 1351 BA. Prolonged storage of a solution with low binder content may result in turbidity and sedimentation. Only PU grade solvents should be used (< 0.05 % water). The solvent should not contain reactive groups.

Application

Desmodur BL 3175 SN can be used as the hardener in colorfast and weather-stable, one-component polyurethane coatings. The stoving temperature can be significantly reduced by the addition of a catalyst, e.g. dibutyltin dilaurate (DBTL), without reducing storage stability. The product is used in high-grade industrial finishes (electrical appliances, small components, can coatings, coil coatings, etc.) and in primer surfacers and topcoats for automotive finishing. It can also be used as an additive in conventional stoving systems to improve flexibility and adhesion.