NIR Detection of Thin-Walled PET Containers with Liquid
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thin walled polyethylene terephthalate (PET) containers, especially those containing liquids, are difficult to detect and sort due to interference from liquids in near infrared detection systems used in recycling facilities, leading to reduced recycling efficiency.
Innovation Solution
A method involving irradiation with near infrared radiation, measuring radiation at specific wavelength regions, determining and adjusting ratios to compare with preset thresholds, and processing these measurements to enhance the detection and separation of PET polymer materials, particularly using wavelength regions around 1660 nm and 1730 nm to improve detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thin walled PET containers are used to reduce cost and environmental impact, then manufacturing cost and environmental footprint are reduced, but detection accuracy and sorting reliability deteriorate due to small amount of PET material and liquid interference
Solution Approach 1:
The patent changes the detection parameters by using multiple wavelength regions (including 1660 nm and 1730 nm) and adjusting measurement ratios to enhance PET signal detection. This allows thin-walled containers with minimal PET material to be detected accurately by optimizing the detection parameters rather than increasing physical detection intensity.
Solution Approach 2:
The patent combines measurements from multiple wavelength regions to create a composite detection signal. By analyzing the ratio of radiation at different wavelengths (particularly 1660 nm and 1730 nm), the system creates a composite fingerprint that identifies PET material even when present in thin walls and partially obscured by liquid interference.
2Loss of substance
If thin walled PET containers are used, then material usage and environmental impact are reduced, but the amount of detectable PET material decreases making identification more difficult
Solution Approach 1:
The patent optimizes detection parameters by selecting specific wavelength regions (1660 nm and 1730 nm) where PET exhibits characteristic absorption patterns. By changing from broad-spectrum detection to targeted wavelength detection, the system enhances sensitivity to small amounts of PET material in thin-walled containers.
Solution Approach 2:
The patent replaces physical/mechanical detection approaches with spectroscopic measurement. Instead of relying on physical properties like thickness or mass that are difficult to measure in thin-walled containers, the system uses optical spectroscopy to detect the molecular fingerprint of PET, enabling detection of minimal material quantities.
3Adaptability or versatility
If liquid is present in PET containers, then containers can be reused or recycled with content, but liquid interference with infrared detection systems worsens detection capability
Solution Approach 1:
The patent converts the harmful liquid interference into a beneficial detection feature. By selecting wavelength regions where liquid and PET have different absorption characteristics (particularly 1660 nm and 1730 nm), the system uses the liquid's presence as a reference to enhance rather than hinder PET identification through ratio analysis.
Solution Approach 2:
The patent introduces ratio analysis as an intermediary processing step between raw detection signals and final identification. This intermediary calculation method separates the liquid interference signal from the PET signal by comparing measurements at multiple wavelengths, allowing the detection system to filter out harmful interference and isolate the target material signature.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method significantly improves the detection efficiency of PET materials, including those with liquids, by adjusting measurements to enhance the identification and separation of PET polymer materials, thereby increasing recycling rates and reducing false identifications.
Implementation Method 1
Near infrared (NIR) based sorting systems used in today's industry sense in the range of about 800 nm to 2400 nm... As the NIR radiation interacts with the sample surfaces energy to varying degrees is absorbed from the radiation at certain wavelengths, the amount of radiation absorbed and at which wavelengths being characteristic to the sample chemistry.
Data Source
AI summary
Disclosed herein are methods to improve detection of PET polymer materials within a waste material to be sorted. The methods disclosed allow for municipal solid waste to be separated so that PET polymer materials, including those containing liquids, are separated for recycling, or other purposes. PET polymer materials, such as water bottles which have been disposed of while still containing liquid may now be separated by the enhanced methods disclosed herein.