TY - JOUR
T1 - Chain extension studies of water-borne polyurethanes from methyl ethyl ketoxime/ε-caprolactam-blocked aromatic isocyanates
AU - Subramani, S.
AU - Cheong, I. W.
AU - Kim, J. H.
PY - 2004/12/20
Y1 - 2004/12/20
N2 - A series of water-based blocked aromatic polyurethane dispersions (BPUDs) were prepared by prepolymer mixing process, using toluene 2,4-diisocyanate (TDI), 4,4′-di-p-phenylmethane diisocyanate (MDI), poly (oxytetramethylene) glycol (PTMG), dimethylol propionic acid (DMPA), methyl ethyl ketoxime (MEKO) and ε-caprolactam (CL). Particle size, viscosity, pH, molecular weight, storage stability, and deblocking temperature of the BPUDs were measured and compared. Chain extension of BPUD was carried out with three types of chain extenders, hexamethylene diamine (HMDA), isophorone diamine (IPDA) and tetraethylene pentamine (TEPA), at various de-blocking temperatures. Tensile and thermal properties of the chain extended BPUD films were investigated and results confirmed that MEKO-BPUDs de-blocked at lower temperature than ε-caprolactam-BPUDs. The Tg values of the chain extended BPUDs were higher than those of the BPUDs and pure PTMG. Improvement in the thermal stability confirmed the de-blocking and chain extension reaction of blocked PU prepolymers.
AB - A series of water-based blocked aromatic polyurethane dispersions (BPUDs) were prepared by prepolymer mixing process, using toluene 2,4-diisocyanate (TDI), 4,4′-di-p-phenylmethane diisocyanate (MDI), poly (oxytetramethylene) glycol (PTMG), dimethylol propionic acid (DMPA), methyl ethyl ketoxime (MEKO) and ε-caprolactam (CL). Particle size, viscosity, pH, molecular weight, storage stability, and deblocking temperature of the BPUDs were measured and compared. Chain extension of BPUD was carried out with three types of chain extenders, hexamethylene diamine (HMDA), isophorone diamine (IPDA) and tetraethylene pentamine (TEPA), at various de-blocking temperatures. Tensile and thermal properties of the chain extended BPUD films were investigated and results confirmed that MEKO-BPUDs de-blocked at lower temperature than ε-caprolactam-BPUDs. The Tg values of the chain extended BPUDs were higher than those of the BPUDs and pure PTMG. Improvement in the thermal stability confirmed the de-blocking and chain extension reaction of blocked PU prepolymers.
KW - Blocked isocyanate
KW - Chain extension
KW - De-blocking
KW - Dispersion
KW - Polyurethane
KW - Water-borne
UR - http://www.scopus.com/inward/record.url?scp=10044220572&partnerID=8YFLogxK
U2 - 10.1016/j.porgcoat.2004.08.004
DO - 10.1016/j.porgcoat.2004.08.004
M3 - Article
AN - SCOPUS:10044220572
SN - 0300-9440
VL - 51
SP - 328
EP - 338
JO - Progress in Organic Coatings
JF - Progress in Organic Coatings
IS - 4
ER -