Shih-Chieh Wang

A new UV-curable PU resin obtained through a nonisocyanate process and used as a hydrophilic textile treatment

A new UV-curable hydrophilic PU resin was obtained through a green, nonisocyanate, three-reaction process: (1) a bis(cyclic carbonate) (BCC) compound is prepared by inserting carbon dioxide into an epoxy resin (DGEBA) at atmospheric pressure; (2) an amino-terminated hydrophilic PU (NH2-PU) oligomer is obtained through the ring-opening polymerization of BCC utilizing a difunctional amino hydrophilic (polyether) compound such as Jeffamine D-2000; (3) the UV-curable acrylate-PU (UV-PU) prepolymer is obtained as an adduct from the Michael addition of NH2-PU to a diacrylate-terminated compound, 3-acryloyloxy-2-hydroxypropyl methacrylate (AHM). A polyester (PET) textile was treated with this hydrophilic UV-PU prepolymer and then cured by irradiation with UV light. The UV-PU resin was found to crosslink and anchor to the textile fibers after UV irradiation, resulting in a long-lasting hydrophilic surface for the treated textile. The performance properties of the new PU resin on the treated textile were investigated.

Performance properties of self-curing aqueous-based PU system with tri-glycidyl phosphate curing agent

Amino-terminated and carboxylic acid containing aqueous-based polyurethane (PU) dispersion was prepared by a conventional NCO-terminated PU prepolymer process by using isophorone diisocyanate (IPDI), polypropylene glycol-2000 (PPG-2000) and 2,2′-dimethylolpropanoic acid (DMPA) as the key raw materials. A new curing agent, tri-glycidyl phosphate (POG) was prepared from a substitution reaction of phosphorus oxychloride and glycidol. A single-component self-curable aqueous-based PU system is obtained from an addition of POG into aqueous-base PU dispersion and its curing reaction occurred among POG oxiranes and PU amino groups immediately after hydrophobic POG diffused into PU particles (as polymeric micelles). The cross-linked PU resins were resulted on drying at ambient temperature. Original PU dissolved into THF and ethanol. And its gel content increased to 90.1% and sample loss in ethanol decreased to 9.2% of this self-cured PU system with 5.0 phr POG. The limiting oxygen index (LOI) value is 20 of original PU and its LOI reached to 27 of this same self-cured PU system. The improved mechanical and thermal properties of those self-cured PU resins were evaluated, respectively in this report.

Flame retardation behaviors of UV-curable phosphorus-containing PU coating system

Abstract A UV-cured polyurethane (PU)/nano-silica composite with a flame-retarded coating system was obtained from the composition of nano-silica containing a UV-curable PU oligomer and a UV-reactive phosphonic acid [ethylene glycol methacrylate phosphate (EGMP)]. The UV-curable PU oligomer was prepared by an addition reaction of 2-hydroxyethyl methacrylate (2-HEMA) with an NCO-terminated PU pre-polymer; this was then mixed with a methanol dispersion of nano-silica. The UV-reactive phosphonic acid (EGMP) was prepared by a reaction of 2-HEMA with phosphorus pentoxide (P2O5). The curing reaction of the PU/nano-silica composite coating system was carried out by UV irradiation with the aid of a photoinitiator (2-hydroxy-2-methylpropiophenone). The thermal properties of these PU/nano-silica composite coatings were investigated by the measurements of dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively. A phosphorus (phosphonic acid) containing ingredient, EGMP in PU coating system that provides good adhesion to steel surface and flame retardation. Their physical properties (contact angle, hardness) and flame flammability [limiting oxygen index (LOI), UL-94 test] with various phosphorus contents (different dosages of EGMP) were also evaluated in this report.