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Modified ureas: an interesting opportunity to control rheology of liquid coatings
Author(s) -
Hajas János,
Woocker Axel
Publication year - 2002
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/1521-3900(200209)187:1<215::aid-masy215>3.0.co;2-t
Subject(s) - rheology , urea , fumed silica , chemical engineering , materials science , polyurea , coating , polarity (international relations) , thixotropy , alkyl , organic chemistry , composite material , chemistry , biochemistry , engineering , cell
Modified urea compounds can be used as very powerful liquid rheology additives in coatings. Their rheological impact in various coating systems is directly related to the specific chemical modifications that can be made to the polyurea molecule. Modifications evaluated were made using end groups of varying polarities such as low polarity alkyl groups, medium polarity segments, or highly polar structures. Analysis of rheological behavior in various types of coatings indicates the presence of two different thickening mechanisms (H‐bonding between urea and urea groups of the additive, and the association of the additive with the binder). These additives result in coatings with exceptional resistance to settling during storage, along with good sag resistance. Some urea type additives used in combination with conventional rheology modifiers such as fumed silicas show synergistic effects. Advantages for coating producers and users will be shown using several practical application examples compared with conventional rheological additives.