Right wingers are overwhelmingly Unionist. As I have pointed out, the areas that voted Yes in the referendum were not SNP heartlands, but Labour ones. The general correlation between Left wing views and support for independence is striking, except for the (usually older) Labour Leftists I have already mentioned.
Probably due to the perceived bias of the larger entity. I.e. In scotland, the uk as a whole is seen as politically to the right of Scotland and therefore righties are sympathetic to the union. In the uk, the eu is seen as politically to the left of the uk and therefore lefties are sympathetic to the eu union.
A lot of it is about how to get more of the "correct" form of government.