Ultrasonic UF Depolymerization for Wood Panel Recycling
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Solution Overview
Problem
Current methods for recycling urea-formaldehyde (UF) from wood-based panels are ineffective due to the reversible polymerization of UF, leading to formaldehyde release and changes in chemical properties of wood materials, which affects the production of new wood-based panels.
Innovation Solution
A method involving ultrasonic treatment, centrifugation, and freeze-drying to obtain a fully recycled UF solid, which is then used to replace up to 10% of industrial UF in wood-based panel production, and recycled wood-based panels are processed to create new particle boards with a 50% utilization rate without affecting panel performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional depolymerization methods are used to recycle UF, then UF can be recovered, but the chemical properties of wood materials change and formaldehyde is released, affecting production quality
Solution Approach 1:
The patent applies parameter changes by precisely controlling depolymerization conditions including temperature (60-80°C), pH value (7.0-9.0), and reaction time (2-4 hours) to enable UF depolymerization while preventing negative effects on wood materials and formaldehyde release
Solution Approach 2:
The patent utilizes phase transitions through freeze-drying treatment where the recycled UF solution is frozen and then dried under vacuum, transforming from liquid to solid state while preserving the chemical integrity of the recycled UF and eliminating formaldehyde release
2Productivity
If recycled UF is used in wood-based panel production, then resource utilization improves, but panel performance may be compromised due to chemical property changes
Solution Approach 1:
The patent controls the replacement ratio of recycled UF to industrial UF at 10% and maintains specific pH (8.5-9.5) and formaldehyde content (35-45%) parameters in the adhesive mixture to ensure both high resource utilization and panel performance meet industry standards
3Ease of manufacture
If wood-based panels are disposed of conventionally, then disposal is simple, but environmental pollution occurs and valuable resources are lost
Solution Approach 1:
The patent implements a comprehensive recovery system that collects waste wood-based panels, depolymerizes the UF adhesive, recovers both the wood materials and UF resin, and returns them to production, eliminating environmental pollution while creating economic value from waste
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
The method achieves a 94% recovery rate of UF, allowing it to be reused in wood-based panel production without compromising the panels' performance, and enables the production of new particle boards meeting industry standards with enhanced properties.
Implementation Method 1
conducting an ultrasonic treatment at an ultrasonic frequency of 40 kHz and 50° C. to 80° C. for 40 min to 100 min to obtain a UF aqueous solution I and recycled wood-based panel pieces
Implementation Method 2
centrifuging the UF aqueous solution II in a centrifuge at 10,000 rpm for 2 h to 6 h to obtain recycled UF
Implementation Method 3
freezing the recycled UF obtained in step (2) at −4° C. for 1 d
Implementation Method 4
conducting freeze-drying in a freeze dryer under a vacuum degree of 80 Pas for 6 d to obtain a fully recycled UF solid
Data Source
AI summary
The present disclosure provides a method for recycling urea-formaldehyde (UF) from a wood-based panel. In the present disclosure, the UF is depolymerized by an ultrasonic treatment, and depolymerized UF can be reused for UF manufacture and wood-based panel production. The recycled and treated UF can be repeatedly used in wood-based panel manufacture without affecting performances of the wood-based panel. UF-glued wood-based panels can be recycled, and a recycled wood-based panel raw material can replace at least 50% of a non-recycled wood-based raw material for particle board production without affecting performances of the wood-based panel.