Capsulated blowing agent is a kind of thermoexpandable microcapsules and physical blowing having an average diameter of 10 to 60 μm. It starts to soften with heating and the encapsulated blowing agent(liquid hydrocarbon) starts to gasify to increase internal pressure and causes the shell to expand. The shells which are softened and expanded with the pressure of gasified hydrocarbon make more smooth surfaced sponge and thin screen-wall paper compare to chemical blowing agent.