Best paint to protect composite front door from sunlight?

ThisIsWeird

ITM, the door appears to have a thin outer film which is shredding off. Any idea what this is?
If you lightly wire brush it, does it come off cleanly? 

Albermarle

ThisIsWeird said:

ITM, the door appears to have a thin outer film which is shredding off. Any idea what this is?
If you lightly wire brush it, does it come off cleanly? 

If you see a PVC window ( for example) that is coloured or has a wood effect finish, this is achieved by the manufacturer covering the usual white PVC with a very thin decorative film, which adheres to the PVC surface.
The film should be manufactured to high standards, and be able to resist weathering/UV damage and be guaranteed for 10 years +
I can see from googling that composite doors can also be covered with similar film to get a decorative effect.
So most likely it is this film that is shredding off. I guess it will need to be removed before any painting takes place or the finish will be poor.
Could be a long job to get it all off.......

Okey00001

Do you know what brand it is? They should advise you what to do.

If can be painted, will it last through wet weather, hot sunshine? 

ThisIsWeird

Almost certainly a specialist paint like Zinsser AllCoat 15-year will do the job admirably. But I'd confirm what the door's surface material actually is, and whether even 'Allcoat' may first benefit from the use of a primer.
I have used AllCoat (satin anthracite) to refinish an old van's faded bumpers, and the result looked like new replacements. But I have noticed the odd flake has come off over the next year or so, one when I used masking tape to hold a glued reflector in place. It may be that I didn't prepare - clean - the surface as well as I'd thought, or it could be that the plastic used was not that compatible. Some plastics are 'waxy'.
I suspect that most composite doors are surfaced in a thermoset - GRP or similar resin - so should clean up well (the OP's needs a thorough wire brushing) and should then take the AllCoat with no issues.
Possibly, if the door is south-facing, a lighter shade might be recommended, not so much because it may fail, but just to reduce movement in the door.