Vinyl siding is an engineered product made primarily from polyvinyl chloride (PVC) resin. Vinyl siding consists of two layers, the capstock and the substrate. The capstock carries the pigment and provides resistance to UV light.
Vinyl siding is available in many colors and textures. However, because it is normally exposed to the elements, vinyl siding will fade over time. Most manufacturers offer 50-year warranties that their products are fade resistance over that period of time. While light and pastel colors can easily meet this hurdle, darker colors tend to fade more than lighter ones.
Vinyl Siding Process Monitoring
Vinyl siding is manufactured in a co-extrusion process that can suffer from variabilities caused by both the raw materials and the equipment. Raw materials, such as titanium dioxide, pigments, fillers, and lubricants change from lot to lot affecting the composition of the final product.
Extruders, feeders, heaters, pullers, blenders, vacuum pumps, and other equipment used in the co-extrusion process, directly affect process parameters such as temperature, pressure, production speed and ultimately, color.
Color values are good indicators of process quality. All parameters in the production process including the temperature, pressure, production speed, feeders, and pumps have a direct impact on color values.
Equitech’s IPS, In-Line Process Spectrophotometer, makes possible continuous color measurement directly in the process. The IPS uses fiber optics and probes to illuminate the sample and transport the signal back to the analyzer. Customers have a choice of probes for contact or non-contact measurement.
For customers wanting to measure directly in the polymer melt before the extrudate is formed, Equitech offers the RPMP, Reflection Polymer Melt Probe. The RPMP is installed in the exit adapter of the capstock extruder using a ½”-20 Gefran® UNF thread where it enters in direct contact with the melt stream.
Benefits of the In-Line Process Spectrophotometer
The value added by using Equitech’s IPS allows for a comprehensive quality audit trail of final product. This prevents off-specification batches from being made which combined with the closed-loop control helps reduce waste.