New rigid vinyl compound molding technology

Abstract

AbstractDuring injection molding, it is not uncommon for shear heating to cause localized temperatures exceeding 300°C. This heating, if not suppressed, can cause vinyl degradation. Three main factors influence shear heating. They are (a) mold design, especially restrictions such as small gates; (b) injection conditions, especially injection velocity; and (c) compound viscosity. To address the compound factor, two new vinyl compounds have been created for custom injection molding, which are especially designed to suppress the shear heating temperatures. Geon® M3700 has good impact at room temperature, and Geon® M3800 has outstanding impact at room temperature and at low temperatures. These compounds use a new technology that produces a balance of properties never before achievable. These innovative compounds show enhanced processability including improved static thermal stability, improved shear stability, tolerance of higher injection screw rpms, tolerance of higher injection speeds, the ability to mold at lower injection pressures, reduced molding cycles, and the ability to fill thin part walls. Also designed into the compounds are improved color fastness during exposure to light, improved appearance, and reduced corrosiveness. Other properties such as impact strength, tensile strength, modulus, heat deflection temperature, hardness, UL flammability rating, specific gravity, and mold shrinkage remain comparable to older technology.