Multi-Layer Lignocellulose Core Heating via High-Frequency Field
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Solution Overview
Problem
Existing processes for producing multilayer lignocellulose materials lack control over temperature differences between exterior and interior layers, leading to inefficiencies in the production of these materials.
Innovation Solution
A process involving separate mixing and layer-by-layer scattering of lignocellulose materials with specific additives, followed by high-frequency electrical field application and hot pressing, allows for controlled temperature differentiation between the core and outer layers, optimizing the production of multilayer lignocellulose materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high-frequency energy is applied to heat the material before scattering, then the interior layer temperature can be increased, but the control over temperature differences between exterior and interior layers is lost
Solution Approach 1:
The invention pre-heats the core layer material before scattering by passing it through a heating zone where infrared radiation or hot air heats the material to a temperature 10-50°C above ambient. This preliminary heating action ensures that when the core layer is scattered and subsequently pressed, the interior layer achieves the desired temperature without requiring high-frequency energy application during the pressing process, thereby maintaining control over temperature differences.
Solution Approach 2:
The invention divides the heating process into separate stages: pre-heating of the core layer material before scattering, and controlled heating during pressing. This segmentation allows independent optimization of each stage - the pre-heating ensures interior layer temperature, while the controlled pressing maintains exterior layer temperature control, resolving the contradiction between achieving high interior temperature and maintaining temperature difference control.
2Productivity
If high-frequency or microwave heating is used before scattering, then heating efficiency is improved, but the ability to selectively heat only the middle layer is limited
Solution Approach 1:
The invention applies heating locally to only the core layer material before scattering, using infrared radiation or hot air directed at the material stream. This localized pre-heating approach allows efficient heating of the core layer without affecting other layers, and the scattered mat structure ensures that only the core layer receives this preliminary heating, achieving both heating efficiency and selective layer heating capability.
3Temperature
If the scattering process is interrupted for heating, then the middle layer can be heated, but the overall production time increases
Solution Approach 1:
The invention performs the heating action during the scattering process itself by incorporating a heating zone in the material path before the scattering point. The core layer material is pre-heated while being conveyed, eliminating the need to interrupt the scattering process. This continuous operation maintains production speed while achieving the required temperature in the middle layer.
4Loss of energy
If the lower outer layer serves as insulation during heating, then energy efficiency is improved, but the heating uniformity across layers is reduced
Solution Approach 1:
The invention segments the heating function by using the lower outer layer as an insulating base during the pre-heating of the core layer. This insulation prevents heat loss to the substrate, improving energy efficiency. Simultaneously, the scattered mat structure and controlled heating duration ensure that heat penetrates uniformly through the core layer without excessive temperature gradients, maintaining heating uniformity despite the insulating effect.
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 process enhances the production efficiency by achieving controlled temperature differences, resulting in improved properties and performance of the multilayer lignocellulose materials.
Implementation Method 1
application of a high-frequency electrical field before, during and/or after the precompaction
Data Source
AI summary
The invention relates to a method for producing multi-layered lignocellulose materials having a core and an upper and a lower cover layer, said method comprising the following steps a) mixing the components, b) spreading the mixtures in layers, c) pre-compressing, d) applying a high-frequency electric field e) hot pressing. According to the invention, a mixture of C) 1-15 wt.-% of a binding agent selected from the group consisting of aminoplastic resin and organic isocyanate having at least two isocyanate groups [components C)], F) 0.1-3% alkali-/akaline earth salts, for the cover layers of the lignocellulose particles G) with H) 1-15% of a binding agent selected from the group consisting of aminoplastic resin and an organic isocyanate is mixed. After step a) the mixture for the core contains, with respect to the total dry weight of the mixture of the components A)-F) 3-15% water, the mixture for the cover layers of the components G)-K) contains 5-20% water, and the following conditions are met: F)≥1,1•components K) and [components F)+components D)]≥1,1•[components K)+components I)].