Lignocellulosic Composite Pressing Without Water-Based Binders
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Solution Overview
Problem
Existing wood-containing composite materials face issues due to the use of fossil-based binders with high water content, leading to energy-intensive drying processes, swelling, and negative environmental impact, while bio-based alternatives like wood-plastic composites are costly and dense, unsuitable for applications like parquet flooring.
Innovation Solution
A method involving mixing lignocellulosic base material with a matrix material, such as polyhydroxyalkanoates or lignin, in fine particle form, without added water, and compressing and heating to the matrix's softening point to create a dimensionally stable, mechanically robust composite with low density and improved environmental footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fossil-based binders with high water content are used, then binding strength is achieved, but energy input increases due to drying requirements
Solution Approach 1:
The invention changes the water content parameter of the binder from high (at least 30%) to low (less than 30%), eliminating the need for energy-intensive drying processes while maintaining binding functionality through the low water content formulation
Solution Approach 2:
The invention extracts and removes the harmful high water content component from the binder system, using instead a low water content binder that achieves binding strength without requiring subsequent drying steps, thus eliminating the energy-consuming drying phase
2Ease of manufacture
If water is added to the binder, then processingability improves, but swelling occurs requiring additional processing steps
Solution Approach 1:
The invention changes the water content parameter from high to low (less than 30%), which maintains adequate processingability during manufacturing while preventing the excessive swelling that occurs with high water content binders, thus eliminating the need for additional compensating processing steps
3Object-affected harmful factors
If bio-based matrix materials are used, then environmental footprint improves, but material density increases making them unsuitable for parquet applications
Solution Approach 1:
The invention creates a composite material system combining lignocellulosic base material (60-100 wt.%) with a bio-based matrix material (0-40 wt.%), where the high lignocellulose content maintains low density suitable for parquet applications while the bio-based matrix provides binding functionality with excellent environmental footprint
4Strength
If fine particle size is used for base material and matrix material, then bonding quality improves, but energy input for comminution increases
Solution Approach 1:
The invention optimizes the particle size parameter to a specific range (at most 500 μm, preferably 63-500 μm), which provides sufficient bonding quality through intimate mixing and contact while avoiding excessive energy input that would result from excessive comminution to much finer sizes
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 process produces a bio-based composite material with high lignocellulose content, low density, and excellent mechanical stability, suitable for applications like parquet flooring, with reduced energy input and minimal environmental impact.
Implementation Method 1
the resulting mixture is compressed and heated until the core temperature of the compact reaches or exceeds the softening point of the matrix material
Implementation Method 2
heating the compact at least to the softening point, in combination with compression and the intimate mixing of the dust and powder components, enables a particularly good bond between the two components
Data Source
Figure 1~2
AI summary
The invention relates to a method for producing a composite material, in particular in the form of a sheet, comprising the following steps: (a) providing a lignocellulosic base material, in particular in the form of dust, with an average particle size of at most 500 µm, and a thermoplastic matrix material, in particular in the form of powder, with an average particle size of at most 500 µm, preferably at most 100 µm; (b) mixing the base material, matrix material, and optionally at least one further additive, wherein the base material content is at least 70 wt.% based on the total mass of the mixture and wherein the matrix material content is at most 30 wt.% based on the total mass of the mixture; (c) pressing the mixture obtained in step (b) in a hot press at least until the core temperature of the composite material reaches the softening point of the matrix material.The invention further relates to a composite material.