Wood Composite Material with Foam Binder Structure
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Solution Overview
Problem
Current wood composite materials face challenges in achieving low density while maintaining sufficient strength and stiffness for load-bearing applications, often resulting in high density profiles and significant swelling when exposed to moisture due to compaction and cell structure compression during production.
Innovation Solution
A wood composite material with a density of 200-550 kg/m³ and a modulus of elasticity of 4,000-12,000 MPa, comprising long macrofibers and a predominantly fine-pored, closed-cell foam binder structure that minimizes fiber compression and moisture penetration, along with optional modifications like acetylation or thermal treatment to reduce swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional compaction and pressing processes are used to manufacture wood composite materials, then density and strength are improved, but significant swelling occurs when exposed to moisture due to cell structure compression
Solution Approach 1:
The patent applies parameter changes by controlling the moisture content of macrofibers (8-12% initially, 4-6% before binding) and adjusting process temperature (20-40°C during binding, 80-100°C during pressing) to prevent cell structure damage while achieving adequate strength without excessive compaction
Solution Approach 2:
The patent implements preliminary action by pre-drying macrofibers to specific moisture content ranges (8-12%, then 4-6%) before the binding process, and pre-heating the pressing plates to controlled temperatures (80-100°C) before compression, which prevents cell structure collapse and subsequent swelling
2Weight of moving object
If low-density materials with sandwich structure and foam-like core are used, then weight is reduced, but shear rigidity is insufficient leading to high deformations under bending loads
Solution Approach 1:
The patent uses composite materials by combining wood macrofibers (providing tensile and compressive strength) with a foam binder material (providing shear resistance and structural continuity), creating a hybrid material that achieves both low weight and adequate shear rigidity
Solution Approach 2:
The patent applies local quality by positioning foam binder material specifically in regions requiring shear resistance while maintaining lower overall density, and orienting macrofibers to provide localized tensile and compressive strength where needed
3Reliability
If macrofibers and binder are compacted by compressing pressing process with heat, then binder hardening is achieved, but significant compaction occurs particularly at interfaces with press plates
Solution Approach 1:
The patent implements preliminary action by pre-heating pressing plates to 80-100°C before the pressing process, which ensures uniform heat distribution and prevents excessive localized compaction at plate interfaces while still achieving adequate binder hardening
Solution Approach 2:
The patent applies partial compaction pressure (sufficient to achieve binder hardening but not excessive compression) and controls the pressing duration to minimize density profile variations, accepting slightly lower compaction levels to maintain uniformity
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 solution provides a material with reduced swelling and improved moisture resistance, maintaining structural integrity and low weight, suitable for load-bearing applications with minimal compaction and uniform density, outperforming conventional wood-based materials in terms of dimensional stability and weight reduction.
Implementation Method 1
a binder which, in the cured state, has a predominantly fine-pored foam structure
Implementation Method 2
the strands, particles or fibers are acted upon with binder and then compacted by a compressing pressing process
Implementation Method 3
the heat acting on the press plates causing the binder to harden
Implementation Method 4
When water is absorbed, such a deformation can be partially reversed due to the highly hygroscopic properties of the wood and the swelling of the cell walls
Data Source
AI summary
The present invention relates to a wood composite material that has a density of 200-550 kg/m3 and a stiffness of 4000-12000 MPa, measured in the four-point bending test according to EN 789. The wood composite material comprises macro-fibres having a fineness coefficient greater than 20 and a binder, the binder having a foam structure.