PTC Polymer Composite with Embedded Phase Change Material
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Solution Overview
Problem
Existing electrically conductive polymer compositions for moldings with a positive temperature coefficient (PTC) are unsuitable for melting processes like injection molding due to phase change material 'bleeding' and inadequate mechanical properties, limiting their application in heating applications such as electrically heatable textiles.
Innovation Solution
A composition comprising an organic matrix polymer, submicro- or nanoscale electrically conductive particles, and a phase change material with a phase transition temperature between -42 °C and 150 °C, integrated into a polymeric network, allowing for the production of moldings with a PTC effect without morphology changes, ensuring stable electrical conductivity and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid polymer dispersions with PTC effect are used for coatings, then PTC effect can be achieved, but solvents outgas in uncontrolled manner causing craters and bubbles
Solution Approach 1:
The patent changes the physical state parameter of the polymer composition from liquid dispersion to solid granulate form. This eliminates the solvent content issue entirely, preventing uncontrolled solvent outgassing during processing while preserving the PTC effect through the phase change material and conductive additive system.
Solution Approach 2:
The patent utilizes phase transition of the polymer matrix from solid to liquid during processing, then back to solid upon cooling. This allows the composition to be processed like thermoplastics without solvent evaporation issues, while the embedded phase change material provides the PTC effect through its own phase transition at a different temperature range.
2Reliability
If impregnation and coating compositions are applied to textiles, then electrical conductivity can be achieved, but adhesion is inadequate causing chipping and flaking
Solution Approach 1:
The patent extracts the problematic liquid dispersion and coating formulation approach, replacing it with solid granulate composition that is compounded into the polymer matrix before molding. This eliminates the adhesion problems inherent in surface coatings while achieving bulk electrical conductivity throughout the textile material.
Solution Approach 2:
The patent creates a composite material system where conductive additives and phase change material are uniformly distributed within the polymer matrix at the molecular level during compounding. This results in intrinsic electrical conductivity and mechanical integrity throughout the entire material, eliminating chipping and flaking issues of surface coatings.
3Strength
If crosslinking agents and high temperatures are used for coating durability, then adhesion improves, but coating becomes brittle and loses flexibility
Solution Approach 1:
The patent eliminates the crosslinking step entirely by using a thermoplastic processing approach. The solid granulate composition is melted and molded without requiring chemical crosslinking, thus avoiding brittleness while achieving durable adhesion through proper material selection and processing parameters.
Solution Approach 2:
The patent changes the processing temperature parameter to be sufficient for melting the polymer matrix and distributing additives uniformly, but controlled to avoid excessive heat that would cause degradation. This allows achieving good adhesion and flexibility without the need for damaging crosslinking treatments.
4Reliability
If high content of conductive additives is used, then electrical conductivity increases, but mechanical properties deteriorate
Solution Approach 1:
The patent optimizes the concentration parameter of conductive additives to achieve sufficient electrical conductivity for heating applications while maintaining mechanical integrity. The phase change material and polymer matrix work together to distribute stress, allowing lower additive content than conventional approaches while preserving both electrical and mechanical properties.
Solution Approach 2:
The patent creates a synergistic composite system where the polymer matrix, phase change material, and conductive additives work together. The matrix provides mechanical strength, the phase change material provides volume expansion during melting to maintain conductivity network, and the conductive additives provide electrical pathways, achieving both high conductivity and good mechanical properties at optimized additive levels.
5Reliability
If phase change material is used for PTC effect, then temperature regulation is achieved, but material bleeds out during processing
Solution Approach 1:
The patent embeds the phase change material within the polymer matrix and conductive additive network to form an integrated composite. The polymer matrix acts as a containment structure that prevents bleeding out during processing, while the phase change material remains free to undergo phase transitions and provide the PTC effect when activated during use.
Solution Approach 2:
The patent selects a phase change material with a transition temperature significantly below the polymer melting point. This temperature parameter separation ensures that during high-temperature processing, the phase change material remains solid and trapped within the matrix, preventing bleeding out. During use at lower temperatures, it can freely transition and provide PTC 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
The solution enables the production of electrically conductive moldings with a significant increase in PTC intensity upon temperature increase, maintaining morphology and mechanical properties, suitable for applications in electrically heatable textiles, achieving a heating power of several watts per unit area.
Implementation Method 1
at least one phase change material with a phase transition temperature in the range from -42 °C to + 150 °C
Implementation Method 2
the PTC effect results from the increase in volume of the phase change material as a result of the temperature increase
Implementation Method 3
submicro- or nanoscale, electrically conductive particles
Implementation Method 4
achieve a heating power of several watts per unit area
Data Source
Figure 1a
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AI summary
The invention describes electrically conductive shaped bodies with an inherent positive temperature coefficient (PTC), produced from a composition which contains at least one organic matrix polymer (compound component A), at least one submicroscale or nanoscale, electrically conductive additive (compound component B) and at least one phase-change material with a phase-transition temperature in the range of from -42°C to +150°C (compound component D). The phase-change material is incorporated into an organic network (compound component C). The electrically conductive shaped body with an inherent PTC effect is, in particular, a filament, a fibre, a spun-bonded web, a foam, a film, a foil or an injection-moulded article. The switching point for the PTC behaviour is dependent on the type and also the phase-conversion temperature of the phase-change material. By way of example, a self-regulating surface heater in the form of a foil and/or a textile can be realized in this way.