NIR Spectroscopy for Plastic Bale Composition Analysis

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Solution Overview

Problem

Current methods for quality control of plastic waste pressed into bales are complex, non-reproducible, and inadequate for efficient documentation, leading to economic risks for waste preparation operators due to fluctuating plastic proportions and lack of comprehensive assessment.

Innovation Solution

A procedure using near-infrared (NIR) spectroscopy and visual imaging to quickly and accurately determine the proportion of polyolefins like polyethylene and polypropylene in bales, enabling rapid, reproducible, and documentable quality control by recording spectra from multiple sides and using color cameras to detect dark contaminants.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual sorting and evaluation of bale samples is used, then quality assessment can be performed, but processing time is extremely long (4 hours per bale) and productivity is very low (2-3 bales per day)

Engineering Contradiction:
Improvequality assessment accuracyVSAvoidbales processed per day
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces manual mechanical sorting and evaluation with an automated optical measurement system. A camera captures images of the bale, and image processing algorithms automatically determine plastic composition and quality parameters, eliminating the need for manual sorting while maintaining measurement precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a digital copy (image) of the bale's surface and internal structure, which can be analyzed computationally. This digital representation allows for rapid automated evaluation without physically handling or manually sorting the actual bale materials, dramatically increasing processing speed.

Inventive Principle:
Principle #26Copying

2Reliability

If manual quality control methods are used, then quality assessment is possible, but the process is non-reproducible and documentation is insufficient

Engineering Contradiction:
Improvequality check reproducibilityVSAvoidquality documentation completeness
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent implements an automated feedback system where image data is processed through standardized algorithms to generate objective quality assessments. This automated feedback loop ensures consistent, reproducible results and automatically documents all quality parameters with precise measurements, eliminating subjectivity and information loss.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent transforms qualitative manual assessment into quantitative measurable parameters through image analysis. By converting visual information into numerical data (plastic composition percentages, quality scores), the system achieves reproducible measurements and comprehensive digital documentation that can be objectively verified and stored.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If comprehensive quality assessment of all bales is performed manually, then complete quality control is achieved, but the economic cost and time investment are prohibitively high

Engineering Contradiction:
Improvecomprehensive quality controlVSAvoidtime per bale evaluation
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces time-consuming manual evaluation with automated optical inspection. The camera-based system captures and analyzes bale images rapidly, providing comprehensive quality assessment for all bales without the prohibitive time cost of manual methods, enabling complete quality control at scale.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

Enables fast, comprehensive quality control of bales, reducing processing time from hours to minutes, allowing for evidence-based assessment and minimizing economic risks by accurately determining plastic proportions and identifying inadequate truckloads, thus improving cost efficiency.

Implementation Method 1

a close infrared spectrum (NIR spectrum) of at least two sides of the bale is recorded, i.e. the proportion of close infrared radiation reflected by the surface of the bale is detected

Methodology Applied
Scientific EffectNear-infrared spectroscopy: Absorption Spectroscopy

Data Source

PatentEP3465151B1Process and installation for analysing bulk materials
Publication Date: 2022.10.12 MTM PLASTICS
  • EP3465151B1 patent drawingFigure 1~2
  • EP3465151B1 patent drawingFigure 3

AI summary

The invention relates to a method and an apparatus for easily determining the composition of plastic waste that has been pressed into bales. Here, the proportion of plastic on at least one surface of a bale is determined with the aid of an NIR spectrum and, optionally, an image from a visual system. In a preferred embodiment, the proportion of plastic of a bale is determined on a plurality of sides of a bale. This increases the accuracy of the method. By way of the method according to the invention and the apparatus according to the invention, it is consequently possible to undertake a quality control of plastic waste that has been pressed into bales, which quality control is fast, reproducible and documentable.