| abstract |
Natural occurring thermoplastic resins are used as a substitute for process oils and/or hydrocarbon resins, as well as for tackifiers, softeners, extenders, processing aids, and cure retarders, in rubber stocks, as for example, a rubber skim stock used in making a tire. The resins, which are derived from crude wood rosin, are high melting thermoplastic resins having carboxylic acid groups and are insoluble in aliphatic hydrocarbons. The source of the natural occurring resins is in ample supply as they are obtained from pine trees grown in North America. |