Stampable Sheet Eccentric Particle Dispersion
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Solution Overview
Problem
Conventional stampable sheets used for sound absorption and structural applications face challenges in achieving a balance between weight reduction, surface quality, mechanical strength, and sound absorption properties due to irregular thermal expandable particle distribution and coagulation issues during production.
Innovation Solution
The method involves eccentrically locating thermal expandable particles toward one-side surfaces of the web and stampable sheet through a foam-paper-making process, ensuring uniform dispersion and preventing coagulation, which enhances mechanical strength and sound absorption by creating a high-density surface layer and a lighter interior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal expandable particles are coagulated during paper making to prevent discharge, then particle retention is improved, but surface irregularity increases and mechanical strength decreases
Solution Approach 1:
A water-soluble binder is introduced as an intermediary substance that facilitates particle retention without causing coagulation. The binder adheres particles to the web during paper making, then dissolves during expansion to allow uniform particle distribution and prevent surface irregularities
Solution Approach 2:
The physical-chemical state of the binder is changed from solid/adhering state during paper making to dissolved state during expansion. This parameter change allows the system to achieve particle retention in the first stage and uniform distribution in the second stage without compromise
2Strength
If web thickness is increased to enhance stiffness, then mechanical strength is improved, but weight increases
Solution Approach 1:
Thermal expandable particles are incorporated into the web to provide expansion capability. During heating, these particles expand to increase the thickness and stiffness of the final product without requiring increased web thickness in the compact state, thereby reducing weight
Solution Approach 2:
The web is formed as a composite material containing reinforcing fibers, thermoplastic resin, and thermal expandable particles. This composite structure allows the web to achieve enhanced stiffness through particle expansion rather than simply increasing the thickness of the compact web, optimizing the weight-stiffness ratio
3Strength
If expanding property is enhanced to increase thickness, then mechanical strength is improved, but the enhancement is limited by spring back action
Solution Approach 1:
Thermal expandable particles are added to provide an additional expansion mechanism beyond the spring back action of reinforcing fibers. These particles expand thermally to contribute to thickness increase, thereby enhancing the overall expanding property and mechanical strength of the stampable sheet
Solution Approach 2:
The stampable sheet is designed as a composite material combining reinforcing fibers, thermoplastic resin, and thermal expandable particles. This composite structure enables synergistic expansion where both the spring back action of fibers and thermal expansion of particles contribute to the overall expanding property, overcoming the limitations of fiber spring back alone
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 approach results in a lightweight expansion molded product with improved bending strength, stiffness, and sound absorption properties while maintaining excellent surface quality, suitable for automotive and building materials.
Implementation Method 1
the stampable sheet is mixed with thermal expandable particles having a property of expanding under heating and then expanded by heating to forcedly increase the thickness of the sheet
Implementation Method 2
the stampable sheet is heated, the thermoplastic resin is melted and at the same time, the thickness is returned to the original web thickness before the pressing due to the action of spring back inherent to the reinforcing fibers
Implementation Method 3
heating and pressing the web and solidifying under cooling
Implementation Method 4
the thickness is returned to the original web thickness before the pressing due to the action of spring back inherent to the reinforcing fibers
Implementation Method 5
When such particles are heated, the hydrocarbon is vaporized and expanded, while the thermoplastic resin is softened, whereby the particles are expanded into spheres
Data Source
AI summary
Web containing a thermoplastic resin, reinforcing fibers and thermal expandable particles dispersed therein. The thermoplastic resin and the reinforcing fibers are uniformly dispersed in a thickness direction and the thermal expandable particles are eccentrically located toward one-side surface of the web, wherein opposite sides of the web have substantially different specific gravity and density.