You can get bag gloves - if that's all you hit, then they should be fine.
They are quite thin and usually leather and padded around the knuckle area. Unfortunately sweating into gloves is a stinky bi-product of boxing!
Although you can hit a bag with bare hands - if you are hitting hard you need some bag gloves. Some days I use my bare hands, some days I do bag mitts and others I like to whack it to pieces with my boxing gloves - although you don't feel the impact as much with boxing gloves. By that I mean that there is more padding, so you don't get the "feel" of the hit rather than that boxing gloves protect your hands more.
Hope that made sense