Although the 3D glasses will protect your eyes from the intensive light and radiant lights, it will not be used as sunglasses which will be used to prevent the uv rays. The 3d glasses will help you filter the second lights from the screen. They can not be worn outside as the sunglasses.
Oh my god, this is quite funny anyway. Actually, 3d glasses are designed to help people better enjoy the exciting moments in 3d movies. However, 3d glasses will make you feel sick, dizzy or somewhat, despite their dark lenses could resist some lights. Therefore, it would not be wise for you to take it home and use as sunglasses. Maybe you just need a pair of sunglasses, Amazon is a good place with a lot of nice sunglasses.
Of course, no. you should not wear them as sunglasses outside in the sun light. First, for the construction, they can only block one kind of light wave. And one lens will block clockwise circular light and the other will block counter clockwise circular light. Comparing with them, Sunglasses will block more light waves. Also, sunglasses are polarized so they can protect your eyes from uv rays and the strong light when you go outsides. But 3d glasses can not achieve this function. But the 3D effect relies on your two eyes each seeing a slightly different image, in which your brain then combines into a three dimensional picture. And also you should know that different 3D displays achieve this in different ways. Generally speaking, when you have worn a pair of 3d glasses while watching 3d movie, it will make you feel that you are just in the real phenomenon. This feeling just attracts many people. So you can have them when have movie.