Polyurea coating systems as sealants for the exterior of fuel tanks

A coating composition obtainable by mixing components (A) and (B) of a coating system with each other,

• wherein component (A) comprises at least one constituent (a1) containing at least two aromatic moieties and bearing at least two primary and/or secondary amino groups, wherein at least one of the primary and/or secondary amino groups is directly bound to each of the at least two aromatic moieties, and wherein the amount of any fillers present in component (A) does not exceed 5 wt.-%, based on the total weight of component (A),
• wherein constituent (a1) is present in component (A) in an amount in the range of from of 50 to 95 wt.-% based on the total weight of component (A),
• wherein component (B) comprises at least one constituent (b1) containing at least one aromatic moiety and bearing at least two isocyanate groups,
• wherein each of components (A) and (B) has a solid content of at least 95 wt.-%, based on the total weight of the respective component,
• characterized in that constituent (b1) present in component (B) bears at least one carbodiimide and/or uretonimine unit and further comprises at least one structural unit (I):
• wherein R1 is a C2 to C8 alkylene residue, and parameter m is an integer in the range of from 1 to 200;
• wherein for preparing the constituent (b1) at least one aromatic diisocyanate is subjected to a reaction with at least one polyether diol;
• and
• characterized in that constituent (a1) further comprises at least one structural unit (II):
• wherein R2 is a C2 to C8 alkylene residue, and
• parameter n is an integer in the range of from 1 to 100.

A two-component (2K) coating system consisting of two components (A) and (B) being separate from each other,

• wherein component (A) comprises at least one constituent (a1) containing at least two aromatic moieties and bearing at least two primary and/or secondary amino groups, wherein at least one of the primary and/or secondary amino groups is directly bound to each of the at least two aromatic moieties, and wherein the amount of any fillers present in component (A) does not exceed 5 wt.-%, based on the total weight of component (A),
• wherein constituent (a1) is present in component (A) in an amount in the range of from of 50 to 95 wt.-% based on the total weight of component (A),
• wherein component (B) comprises at least one constituent (b1) containing at least one aromatic moiety and bearing at least two isocyanate groups,
• wherein each of components (A) and (B) has a solid content of at least 95 wt.-%, based on the total weight of the respective component,
• characterized in that constituent (b1) present in component (B) bears at least one carbodiimide and/or uretonimine unit and further comprises at least one structural unit (I):
• wherein R1 is a C2 to C8 alkylene residue, and parameter m is an integer in the range of from 1 to 200;
• wherein for preparing the constituent (b1) at least one aromatic diisocyanate is subjected to a reaction with at least one polyether diol;
• and
• characterized in that constituent (a1) further comprises at least one structural unit (II):
• wherein R2 is a C2 to C8 alkylene residue, and
• parameter n is an integer in the range of from 1 to 100.