InSpectro NIR: Inline Near-Infrared Spectroscopy

The ColVisTec NIR spectrophotometer operates in the 1000 – 2500 nm wavelength range and delivers real-time analytical data from inside extruders, reactors, mixers, and other process equipment. By continuously "looking inside" the process, it provides 100% control over product quality rather than relying on discrete sampling.

Key Benefits of NIR Inline Monitoring

• Continuous 100% process control instead of sporadic sampling
• Immediate visibility of deviations, drifts, or raw material variations
• Prevention of off-spec production and contamination
• Automated feedback control via direct OPC UA communication with dosing units
• Detection of melt filter performance
• Detection of polymer degradation, yellowing, and cross-polymer contamination

Suitable for a wide range of applications: extrusion, reactive extrusion, compounding, polymer recycling, hot-melt extrusion, powder coatings, chemicals, mixer applications, food & pet food, paints & coatings, and more.

Key NIR Applications

The NIR system supports a wide range of measurements across the entire manufacturing chain:

• Moisture & water content measurement — detection of water presence in polymer melts and monitoring of drying processes
• Raw material & feedstock characterization — identification and qualification of incoming materials
• Blend uniformity studies — verification of homogeneous mixing
• Finished product identification & specification — final quality confirmation
• Polymer contamination detection — e.g., detection of PE contamination in recycled PP
• Throughput & homogenization monitoring — signal noise correlates with mixing quality
• Degradation and yellowing detection in recycled polymers

NIR monitoring can be deployed from materials receipt, through the reactor, product work-up, crystallization, filtration & drying, milling, all the way to finished formulation.

Proven Case Studies

1. Water Content & Throughput Detection in Extrusion

In a real extrusion trial, the NIR inline system clearly distinguished between water-containing and dry polymer melts:

• Water in the polymer → lower NIR signal level
• No water in the polymer → higher, stable signal
• Lower throughput (100 kg/h) → high signal noise, indicating poor homogenization
• Higher throughput (300 kg/h) → low noise, indicating good homogenization

This demonstrates the NIR probe's dual capability: measuring both chemical composition (water) and process quality (mixing efficiency) simultaneously.

2. PE Contamination in Recycled PP

Within the RecyColor project, the NIR system successfully detected polyethylene (PE) contamination in polypropylene (PP) recyclate, with a linear correlation (R² = 0.91) across a 0–10% PE contamination range. This enables real-time flagging of off-spec material in polymer recycling streams.