Abstract
The potential of three development isocyanates (meta- and para-tetra-methylxylene diisocyanate (TMXDI) and m-isopropenyl-α-α-dimethyl-benzylisocyanate (meta-TMI)) is illustrated in applications where aliphatic isocyanates are required. Data are given on formulations for reaction injection moulding, surface coatings, radiation-curable coatings, cast elastomers and potting compounds which resist degradation or discoloration by light and weather. In the case of cast polyurethane elastomers and microcellular elastomers — where light stability is not commercially significant – the use of these tertiary aliphatic diisocyanates gives valuable combinations of physical properties as well as processing benefits.
Generally direct replacement of an existing diisocyanate is not satisfactory, but good results are readily obtained by reformulation to adjust for the chain mobility and reactivity of the particular TMXDI isomer.
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