Arctornis sp.

Lymantriidae.

Not really possible to say which species without dis-section of the genitalia.

Take a look at Jeremy Holloway's Moths of Borneo (vol 5. Arctornithini - gallery) to see just how much diversity there is in the genus, and how many are very similar to the species in your photo!

The diversity in Hong Kong is also quite high - there are at least a dozen similar species.

cheers,

Roger.