Blacklight sensitive paper
Paper brighteners used in modern papers contain fluorescent materials that make the paper glow under a black light. Bright white paper will actually glow fairly well. 

Any paper that's been treated with these types of brighteners will glow under a black light. Typically, you'll see that neon colors are going to be the "brightest", and so they will glow the best. 

In this case, it's not anything to do with what the material is made from, but how it's colored/treated. The chemicals are called Optical Brightening Agents, and are used in a wide variety of products to add fluorescence. Think of any neon/fluorescent paint, crayons, safety vests, etc. The OBAs work by reflecting invisible (to us) UV light as just-visible blue light, which is why they glow.