For example, preferred are those having a relative viscosity of from 2.0 to 7.0, more preferably from 2.5 to 6.0, measured in a 98% concentrated sulfuric acid solution having a sample concentration of 0.01 g/ml at 25??? C. [0075] The thermoplastic resins to form the neighboring layer (??) may contain, if desired, additives such as plasticizer, antioxidant, nucleating agent and colorant suitable to