Stoving Enamel White 1 Quality
Stage I: Charging 1.500 Zinc Naphthanate 6% 20.000 TiO (R)
2 2.000 Short DCO Alkyd 60% 2.000 Toluene 1.500 N Butanol 27.000 Total Stage II: Stabilization & Cleaning 10.000 Short DCO Alkyd 60% 1.500 Toluene 1.500 N Butanol 40.000 Total Stage III: Adjustments 20.000 Short Coconut Alkyd 70% 16.000 Toluene 76.000 Total 12.000 Melamine Formaldehyde ±2 (MTO Tolerance ltd) 1.000 Marproof Agent PA 52 4.000 N Butanol 93.000 Total 7.000 Toluene / Alkyd for Viscosity Adj. 100.000 Total
Zinc Naphthanate used in excess to keep more open time to avoid blisters eventhough flash off time is very less. It also acts as a dispersing agent. Short DCO is used purposely inspite of its yellowish colour property as its oil length is around 45 - 48 in comparision with Coconut which has oil length of 32 only. More the oil length better pigment wetting is observed, while DCO being semi drying oil it improves adhesion also. About use of N Butanol many chemist are ignorant, Melamine to Short Oil Alkyd i.e. Amino to Alkyd cross linkage is only possible in Butylated atmosphere. And it also acts as anti-gelling agent.
N.B. Nowadays same formulation is developed by using Short Soya Alkyd also. Author’s Special: If we add 5% epoxy 450XX 75% and 3% DAA in given formulation then it is called Epoxy Dised Stoving Enamel and it even passes Acetone rub test for 1 minute like Epoxy paints.
Another very amazing formulation by author. Part - I 100.000 Short Coconut Alkyd 70% 5.000 Xylene 35.000 MTO Add slowly while stirring 140.000 Total That is Coconut alkyd is converted to 50% solids with 25% MTO plus 25% Xylene, low solids High Viscosity Short Oil Alkyd Part - II As usual formulate the paint as given aside. This gives amazing levelling property due to MTO and embossing of fixture is also well covered and even low solid alkyd gives very good gloss. And cost saving due to low solids, lower requirement of Amino Resin.
N.B. In this formulation we have to take care of Shelf life which is around two months which can be increased by using 2% solution of 10% Benzoic acid in N Butanol.
Important tip: Small quantity of Para Toluene Sulphonic Acid (PTSA) 20% solution can be used for making paint low bake and to reduce baking schedule. It should be added only at the time of application as it
reduces shelf life drastically.