Polymer Fiber Preblend Process for Thermal Degradation Prevention
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Solution Overview
Problem
Existing processes for producing wood fiber or cellulose fiber composites are inefficient due to low throughput and poor dispersion of fibers in the polymer matrix, leading to extended residence times in extruder barrels and potential thermal degradation of cellulose, resulting in undesirable color and odor in the composite material.
Innovation Solution
A process involving the formation of a preblend of polymer and fiber materials, agitated to a temperature beyond the VICAT softening point, followed by controlled velocity adjustments and comminution to create a precursor material with improved fiber dispersion and reduced thermal stress, allowing for enhanced processing efficiency and prevention of thermal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cellulose fibers and polymer granulates are processed separately in an extruder barrel, then the polymer can be easily blended, but the throughput is low and residence time is extended causing thermal degradation of cellulose
Solution Approach 1:
The invention applies preliminary action by pre-coating the cellulose fibers with polymer material before extrusion. The polymer and cellulose are mixed in a preliminary blending step where polymer granulates are coated onto the fiber surfaces, creating a pre-coated mixture that requires shorter residence time in the extruder while ensuring complete wetting and dispersion of fibers in the polymer matrix during final extrusion
2Manufacturing precision
If high temperature is applied to melt polymer for blending, then dispersion is improved, but cellulose fibers undergo thermal degradation causing brown color and pungent odor
Solution Approach 1:
The polymer coating is applied to cellulose fibers in advance at controlled temperatures that prevent fiber degradation. This preliminary coating step allows the polymer to adhere to fiber surfaces without subjecting the cellulose to excessive heat that would cause browning and odor, while still achieving complete wetting during extrusion
Solution Approach 2:
The invention changes the temperature parameters by conducting the preliminary blending at temperatures below the degradation point of cellulose (typically maintaining temperatures under 100°C during mixing), while still achieving adequate polymer coating. This parameter control prevents thermal degradation while ensuring proper dispersion
3Manufacturing precision
If low bulk density fiber material is processed, then fiber dispersion is achieved, but the throughput of the compounder is reduced
Solution Approach 1:
By pre-coating fibers with polymer material before extrusion, the invention reduces the residence time required in the extruder barrel. The preliminary blending step ensures that polymer and fiber are already combined in a controlled manner, allowing faster processing speeds and higher throughput while maintaining adequate fiber dispersion in the final composite
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 results in a precursor material that enhances fiber dispersion and processing efficiency, preventing thermal degradation and improving the quality of the final composite material granulate by ensuring better wetting of fibers with the polymer matrix, thus improving throughput and product quality.
Implementation Method 1
agitating the preblend in a blending device comprising a blending means by operating the blending means at a velocity sufficient to bring about an increase of the temperature of the preblend to at least a temperature beyond the VICAT softening point, or a temperature within or beyond the melting temperature range of the polymer material
Implementation Method 2
comminuting the formed intermediate material in a, preferably cooled, comminuting device comprising a comminuting means by operating the comminuting means at a velocity allowing for a decrease in temperature of the intermediate material, until the temperature falls below a final threshold value
Data Source
AI summary
A process for producing a precursor material comprising the steps of, agitating a polymer material and a fibre material in a blending device comprising a blending means operating at a velocity sufficient to bring about an increase of the temperature to at least a temperature beyond the VI CAT softening point or within or beyond the melting temperature range of the polymer material. Thereafter, maintaining the velocity of the blending means and, when the specific motor power needed to maintain the velocity of the blending means increases by a predetermined amount or reaches a predetermined value, reducing the velocity. Repeating the previous step as necessary, until the velocity falls below a first threshold value to form an intermediate material. Finally, comminuting the formed intermediate material in a comminuting device comprising a comminuting means operating at a velocity allowing a decrease in temperature, until the temperature falls below a second threshold value.