As the solvent for the coating agent, a variety of rubber-dissolvable or dispersive solvents are available, examples of which are hydrocarbons (e.g., aliphatic hydrocarbons such as hexane and octane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as toluene); halogenated hydrocarbons; alcohols (e.g., aliphatic alcohols such as ethanol and isopropanol); ketones (e.g., aceton