PTC Resistor Composition for Flexible Sheet Heating Elements
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Solution Overview
Problem
Existing sheet heating elements lack flexibility, durability, and reliability, leading to compromised comfort and durability when used in applications like car seat heaters and steering wheel heaters, and have high manufacturing costs due to complex multi-layered structures and inefficient PTC characteristics.
Innovation Solution
A polymer resistor composition with a cross-linked structure formed from a reactant resin and a reactive resin, incorporating conductive materials like carbon black and graphite, and a liquid-resistant resin, which allows for flexible film formation and enhanced PTC characteristics, improving thermal expansion and resistivity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional polymer resistor is used in a sheet heating element, then the heating function is achieved, but the flexibility and comfort are compromised
Solution Approach 1:
The patent merges the polymer resistor with the base material into a single integrated structure. The polymer resistor is formed by printing resin compositions containing conductive materials directly onto the base material and drying it, eliminating the need for separate resistor layers and complex multi-layered structures. This integration maintains flexibility while achieving the heating function.
Solution Approach 2:
The patent uses a thin-film structure for the polymer resistor formed by printing and drying resin compositions on a flexible base material. This thin-film approach ensures the sheet heating element remains flexible and comfortable for contact with human skin, while still providing effective heating performance through the conductive material network.
2Reliability
If a multi-layered structure is used to improve reliability, then protection is enhanced, but manufacturing cost and complexity increase
Solution Approach 1:
The patent combines the polymer resistor formation with the base material structure into a single integrated process. The resin composition is printed directly onto the base material and dried to form the resistor in situ, eliminating the need for multiple separate layers and complex assembly processes. This reduces manufacturing complexity while maintaining reliability through the integrated design.
Solution Approach 2:
The base material serves multiple functions: it provides mechanical support, acts as the substrate for the polymer resistor, and contributes to the overall flexibility and comfort. This multi-functionality reduces the need for additional protective layers and simplifies the overall structure while maintaining reliability.
3Use of energy by moving object
If conventional resistor materials are used, then heating is achieved, but energy efficiency is insufficient
Solution Approach 1:
The patent optimizes the PTC characteristics by carefully controlling the composition of the resin, the type and amount of conductive materials (carbon black, graphite, metal powder), and the printing/drying parameters. These parameter changes enable the polymer resistor to exhibit superior positive temperature coefficient characteristics, improving energy efficiency by automatically regulating heat output based on temperature feedback.
Solution Approach 2:
The patent uses composite resin compositions containing multiple conductive materials (carbon black, graphite, and/or metal powder) combined with the resin matrix. This composite structure enhances the PTC characteristics and energy efficiency by creating a network of conductive pathways that respond dynamically to temperature changes, providing superior energy regulation compared to single-material resistors.
4Ease of manufacture
If simple printing and drying is used to form the resistor, then manufacturing is simplified, but resistivity control and PTC characteristics are insufficient
Solution Approach 1:
The patent achieves precise resistivity control through optimized printing and drying parameters, including resin composition formulation, printing density, drying temperature, and drying time. These controlled parameters enable accurate regulation of the conductive material distribution and concentration, achieving target resistivity values and PTC characteristics while maintaining the simplicity of the printing-drying manufacturing process.
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 flexible, durable, and reliable sheet heating element with improved PTC characteristics, reducing energy consumption and manufacturing costs while maintaining high thermal performance and comfort in applications like car seat heaters.
Implementation Method 1
PTC characteristic refers to a characteristic such that when the temperature rises, resistance rises with it. A sheet heating element having such a PTC characteristic has self-temperature control of the heat which it emits.
Implementation Method 2
A conductive material used in this type of resistor is typically carbon black, metal powder, graphite, and the like. This resistor emits heat by conducting electricity.
Implementation Method 3
A polymer resistor composition with a cross-linked structure formed from a reactant resin and a reactive resin, incorporating conductive materials like carbon black and graphite, and a liquid-resistant resin, which allows for flexible film formation and enhanced PTC characteristics, improving thermal expansion and resistivity changes.
Data Source
Figure 1A~1B
Figure 2~3
Figure 4A~4B
AI summary
A PTC resistor according to the present invention comprises at least one PTC composition which comprises at least one resin and at least two conductive materials. The at least two conductive materials comprises at least two conductive materials different from each other. The at least one PTC composition may comprise a first PTC composition which comprises a first resin and at least one first conductive material and a second PTC composition which is compounded with the first PTC composition and comprises a second resin and at least one second conductive material. The at least one first conductive material is at least partially different from the at least one second conductive material. One of the first resin and the second resin may comprise a reactant resin and a reactive resin which is cross-linked with the reactant resin. The PTC resistor may comprise a flame retardant agent. The PTC resistor may comprise a liquid-resistant resin.