Hot embossing? Probably need to optimize conditions better.

Maybe need to go hotter, less pressure, lower time.

Can try UV treating COP before hand too.

Hi,

Thanks for your tips.

Can you tell me what is the purpose of the UV treatment before hot embossing? What settings(time, wavelength stc.) do you use in UV treatment?

I've tried other settings during HE, but increased temperature negatively affects the quality, same as low pressure.

Thanks again!

I will say -- I have not tried it, but UV treatment alters the chemical structure by creating COOH groups throughout the polymer, which may affect Tg and brittleness. However -- it may also improve the adhesion between your mold and plastic. Thus, maybe a brief Uv treatment (not longer than 3 min -- just enough to affect the surface), 254nm may help if the reason you are getting bubbles is due to improper "seal" between your mold and plastic. That said -- I do not think this should be the first thing to try.

Your issues are likely more mechanical (rather than chemical) in nature. I.e., need further optimized conditions (as previously discussed), something is wrong with the mold (surface irregularities), or something is wrong with your temperature controller (uneven temperature distribution causing air pockets to form). Also, the way in which you cool your substrate post embossing can affect this, too.

to better help, would need information such as:

What kind of embosser are you using? Some 'fancier' ones will have a vacuum sort of chamber to help ensure there is very little air between the mold and the plastic.

Are you using zeonor 1060? (guessing from your Tg).

How does your bubble formation look? Are bubbles evenly distributed throughout the plastic or are there only certain areas of the plastic that have bubbles? (either random spots between embossings or consistently same area)