Moisture cure polyurethane
Moisture-cure polyurethanes -- or polyurethane prepolymer -- are isocyanate-terminated prepolymers that are formulated to cure with ambient water.[1] Cured PURs are segmented copolymer polyurethane-ureas[2] exhibiting microphase-separated morphologies. One phase is derived from a typically flexible (subambient glass transition temperature, Tg) polyol that is generally referred to as the “soft phase”. Likewise the corresponding “hard phase” is born from the di- or polyisocyanates that through water reaction produce a highly crosslinked material with softening temperature well above room temperature.
Application
[edit]Moisture cure polyurethanes have been widely used in the adhesive and coating industries. Thermal, mechanical, and surface properties of hyperbranched polyurethane-urea (HBPU) moisture cured coatings have been studied in relationship to chemical structure.[3] Different NCO terminated HBPU prepolymers were prepared by reacting hyperbranched polymers with isophorone diisocyanate (IPDI) or 4,4'-bis-methylene cyclohexane diisocyanate (HMDI). A range of NCO/OH eq. ratios from 1.2 - 1.6 was used.
Thermal and mechanical properties of moisture cured polyurethane-urea /clay nanocomposite coatings have been studied in relationship to clay dispersion and intercalation of clay platelets in the urethane-urea matrix.[4] Coatings were prepared by moisture curing of IPDI capped hydroxyl terminated polybutadiene/clay dispersions in a relative humidity (RH) of 50% at 25 °C. Moisture cured polyurethane–urea coatings have been made by reacting 1,2,3-triazole rich polyether polyols with HMDI at NCO/OH eq. ratio of 1.2 to obtain isocyanate-terminated polyurethane prepolymers. The prepolymers were cured under atmospheric moisture to make polyurethane–urea free films. [5]
References
[edit]- ^ Ren, Dakai; Frazier, Charles E. (2012). "Wood/adhesive interactions and the phase morphology of moisture-cure polyurethane wood adhesives". International Journal of Adhesion and Adhesives. 34: 55–61. doi:10.1016/j.ijadhadh.2011.12.009.
- ^ Benedek, Istvan; Feldstein, Mikhail M. (2019-07-05). Handbook of Pressure-Sensitive Adhesives and Products: - Three Volume Set. CRC Press. ISBN 978-1-4398-3311-7.
- ^ Mishra, A. K.; Narayan, R.; Raju, K. V. S. N. (2012). "Structure–property correlation study of hyperbranched polyurethane–urea(HBPU)coatings". Progress in Organic Coatings. 74 (3): 491–501. doi:10.1016/j.porgcoat.2012.01.015.
- ^ Rath, S. K.; Patri, M.; Khakhar, D. V. (2012). "Structure–thermomechanical property correlation of moisture cured poly(urethane-urea)/clay nanocomposite coatings". Progress in Organic Coatings. 75 (3): 264–273. doi:10.1016/j.porgcoat.2012.05.011.
- ^ Kantheti, S.; Sarath, P. S.; Narayan, R.; Raju, K. V. S. N. (2013). "Synthesis and characterization of triazole rich polyether polyols using click chemistry for highly branched polyurethanes". Reactive & Functional Polymers. 73 (12): 1597–1605. doi:10.1016/j.reactfunctpolym.2013.09.002.