| abstract |
Sheet material which incorporates selected particulate is produced using a blown film die (1); polymer containing the selected particulate is supplied to the die inlet so that, when the polymer is extruded through the die and expanded to form a blown film (6), the selected particulate is incorporated in the blown film; and the selected particulate is added to a part only of the polymer supplied to the die, so that the particulate will be present in only a certain part, for example a surface, of the blown film and of sheet material produced from the blown film. |