2010

Incozol® latent curing agents are used in a wide variety of coating, adhesive and sealant applications. They are particularly advantageous where high build properties are desirable, for example, waterproof coatings and construction sealants.

This range of oxazolidines can be used in both one and two component PU systems. In one component systems they are normally used with aliphatic prepolymers. They promote fast through-cure with no carbon dioxide gas evolution. The curing agents hydrolyse on exposure to moisture, yielding reactive amine and hydroxyl functional groups.

In two component systems they can be also be used with aromatic prepolymers or isocyanates.

The Incozol® latent curing agent range consists of Incozol 4 which is a standard bis-oxazolidine curing agent, Incozol HP is a high purity curing agent plus Incozol NC & Incozol K which are non-crystallising curing agents.

Curing Mechanism

The unique properties of the Incozol® latent curing agents are principally determined by the curing mechanism, which differs from the traditional "moisture cure" reaction.

a. Traditional Moisture Curing Routes

In this process, moisture reacts directly with the terminal isocyanate of the prepolymer generating gaseous carbon dioxide. This results in blisters, bubbles or foaming in the coating film.

b. Oxazolidine Curing Route

Moisture reacts preferentially with the oxazolidine rather than with the prepolymer's terminal isocyanate groups. This process of hydrolysis and ring opening of the oxazolidine produces amine and hydroxyl groups. These amine and hydroxyl groups then react sequentially with the isocyanate of the prepolymer without the evolution of carbon dioxide gas. (A small quantity of isobutyraldehyde is generated during this process).