DEVICE AND METHOD FOR MONITORING MATERIAL PROPERTIES OF PLASTICS

Abstract

The invention relates to a device and a method for inline quality checking for plastics during the production process, comprising at least two different measuring devices, wherein the device has a unit for sampling plastic melt from the production extruder, a unit for moulding a flat film from this plastic melt, and units for transporting the flat film to the measuring devices and for finishing the flat film.

Claims

1. Device for in-line quality checking for plastics during the production process, comprising at least two different measuring devices selected from the group of measuring devices for determining the rheological properties, measuring devices for colour measurement, measuring devices for detecting inclusions and gel particles and the like, measuring devices for judging the optical properties, and measuring devices for determining the mechanical parameters, studying the olfactory parameters, wherein the device has a unit for sampling plastic melt from the production extruder, a unit for moulding a flat film from this plastic melt, and units for transporting the flat film to the measuring devices and for finishing the flat film.

2. Device according to claim 1, wherein the device is coupled via an adapter to a side strand of the extruder and the sampling of the plastic melt occurs after opening of a valve.

3. Device according to claim 1, wherein the sampling of the plastic melt is performed through a borehole into the cylinder housing of the output region of the extruder.

4. Device according to claim 1, wherein the sampling of the plastic melt is performed by a displacement body, which is positioned in the melt flow and around which the melt is conducted to a borehole in the cylinder housing of the extruder.

5. Device according to claim 1, wherein the device has a sheet die and a casting roller for moulding a flat film.

6. Device according to claim 1, wherein the device comprises two roller pairs for stretching the flat film.

7. Device according to claim 1, wherein the device comprises a measuring nozzle for determining the rheological properties.

8. Device according to claim 1, wherein the device comprises an area camera for recognizing inclusions and gel particles in the flat film.

9. Device according to claim 1, wherein the device comprises a multispectral sensor for NIR measurement.

10. Device according to claim 1, wherein the device comprises an illumination unit and a sensor for colour measurement.

11. Method for quality checking for plastics during the production process, wherein a defined quantity of plastic melt is conducted directly from a production extruder into the device for quality checking and subsequently moulded into a flat film, whereupon the flat film is studied and judged with the aid of the measuring devices situated in the device.

Description

[0037] The device consists of a housing 1, which has a unit 2 for sampling the plastic melt, which is transported through a measuring nozzle for determining the rheological properties, in particular the viscosity of the melt, into the interior of the housing of the device.

[0038] Subsequently, the plastic melt is moulded by the sheet die 3 and a casting roller 5 into a flat film 6 and guided via deflection rollers to the first visual check by means of an area camera 7 for recognizing inclusions and gel particles. The film is conducted in this case through a housing to exclude scattered light and is illuminated using a dome light and ring lights.

[0039] Subsequently, the flat film is guided further to the colour measurement 8 and NIR measurement 9 by means of a multispectral sensor.

[0040] Before the subsequent study, the film is cut into strips by an edge cut 10. The middle strip preferably has a width between 20 and 25 mm, to thus correspond to the standard test specimen from the film tensile experiment (ISO 527-3), but can also be embodied wider or narrower. The middle strip is stretched between two roller pairs 11, 12 to ascertain the modulus of elasticity. The two edge strips 13 are not used for the tensile experiment.

[0041] All measuring devices and the processing units are situated in a space-saving manner in the housing. The required parameters of the plastic or the plastic film can thus be ascertained directly, still during the production at one location, and the production process can be engaged in if necessary. The quantity of material not corresponding to the quality criteria is thus significantly reduced.

[0042] In addition, measurement points which are situated at different locations along the production device are not necessary due to the single sampling at a single point of the production process.