1. Improvement in Flame Retardancy of Polyurethane Dispersions by Modifying with Flame Retardant Triol
Kunal Wazarkar, Dr. Anagha Sabnis*,
Department of Polymer and Surface Engineering,
Institute of Chemical Technology, Mumbai
A novel phosphorous containing reactive flame retardant was synthesized and incorporated successfully in polyurethane backbone to obtain flame retardant aqueous polyurethane dispersions (FRPUDs). The structure of synthesized phosphorous containing triol was confirmed by FTIR, 1H-NMR and 31P-NMR spectrometry. Further, polyurethane prepolymer was modified with phosphorous containing triol compound in various amounts (30, 40 and 50% on equivalent basis) and FRPUDs were prepared. It was then characterized for mechanical, chemical, thermal and flame retardant properties. It was observed that all FRPUDs exhibited good mechanical properties and improved flame retardancy as compared to the conventional one. The maximum limiting oxygen index (LOI) value of 37 was obtained for FRPUD containing 0.8 wt % of phosphorous and 1 wt % of nitrogen. The flame retardancy was greatly depending on the phosphorous content and increased with increase in phosphorous content. Moreover, nitrogen present in the polyurethane gave rise to synergistic system by acting along with phosphorous improving overall flame retardancy of the coatings.
Reactive flame retardant based on phosphorous was successfully synthesized.
Incorporation of flame retardant improved flame retardancy and thermal properties of PUDs.
With the increase in phosphorous content, flame retardancy of PUDs increased.
PUD-50 exhibited highest LOI of 37 and UL-94 rating of VTM-0.
V.C. Malshe, M.A. Sikchi, Basics of Paint Technology Part-I, Antar Prakash Centre for Yoga, Uttarakhand, India, 2008.
D.K. Chattopadhyay, K.V.S.N. Raju, Prog. Polym. Sci. 32;(2007):352–418.
31P-NMR
ABSTRACT
METHOD
Synthesis of Reactive Flame retardant Triol
Synthesis of Flame Retardant PUDs
Film Properties
STEP 1
DMPA, Polyol, flame retardant compound and acetone were added in a flask and stirred till homogeneous mixture was obtained.
Stoichiometric amount of IPDI containing DBTDL was added to the above mixture dropwise for next one hour.
STEP 2
Chain Extension using Ethylene diamine at 500C for 50 minutes.
STEP 3
Neutralizing agent, Triethylamine was added to make prepolymer water dispersible.
Characterization
Commercial
Conventional
PUD-30
PUD-40
PUD-50
Gel Content (%) -
70.32
72.64
78.92
85.57
Cross Cut Adhesion 5B 4B
Pencil Hardness HB B H 2H 4H
Scratch Hardness
750g
750 Kg
1 Kg
1.5 Kg
Impact Resistance (lbs.inch)
Extrusion: Intrusion:
70.86
64.96
47.24
59.05
35.43
Flexibility (mm) 3 5 55 30 32 37 46
UL-94
VTM-1
VTM-0
Limiting Oxygen Index 22 29 33
Flame retardants are the chemicals used in thermoplastics, thermosets, textiles and coatings to inhibit or resist the spread of fire.
INTRODUCTION
TGA
RESULTS AND DISCUSSION
FTIR
CONCLUSION
1H-NMR
REFERENCES