| 摘要 |
Hollow thermoplastic profiles are from freshly extruded tubing which passes through a calibration die where at least one surface is chilled to an amorphous state, the body of the tubing is adjusted to a temp. above the glass transition temp. of the material, and the tubing is then stretched radially and longitudinally to a diameter controlled by an extension of the calibration chamber. Claimed for making tubular containers, pref. from polyethylene terephthalate (PET) of intrinsic viscosity 0.50-1.10 dl/g in orthochlorophenol, so that when the container is lying horizontal, the radial sag under its own wt. is less than 2%. The material used may be pigmented or filled, opt. is reinforced by incorporation of ground glass fibres or lamellae of mica, graphite or talc. Suitable for tough containers with a high strength/wt. ratio for holding e.g. fluoroescent light tubes, or for packaging liquids or edible pastes. |
