PU Coating for plastic

[LeeWL]

Greetings to all.

Hi... I'm seeking help in 2 pack high gloss PU coating for plastic. I've been handed tis project to help improve the current formulation in my company. Throughout my research, i've failed to solve a problem which is the migration of the PE sheet onto the coating after bein subjected to 65 degrees celsius and 95% humidity for 24 hours. I've been searchin for solutions but in vain.

I noticed that whenever I improved the hardness of my coating, the migration problem deteriorates. However, when I decrease the hardness, my coating would fail the chemical n abrasion test. Also, I've noticed that resins with higher solid content would give very high gloss but most of the time they do not have adhesion on the PC nor ABS plastic.The resin that I use for my coating are mainly PU resin whereas the hardener used is of the isocyanate.

I'd be very grateful if members of the forum would kindly provide me with informations or guide me in formulating or on choosing my raw materials. The coating which I am to formulate has to pass an abrasion test of 150 cycle x 1.64 kg at 40 cycle/minute, an alcohol test of 250 cyle x 1kg at 40 cycle/minute, a gloss of ~90 degree and finally the migration test.

Thank you for your guidance.

[Gordon]

Hi LeeWL

Sorry I can't help on this one other giving this thread a bump. Hoping someone else can help.

[LeeWL]

Thanks Gordan.

I guess its pretty tough luck. I've been trying out some PTFE additives but it doesn't seem to block out the stains.