PTC Screen Printable Ink Double Switching Temperatures
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Solution Overview
Problem
Existing polymeric PTC compositions produced by ink/coating technology often exhibit undesirable Negative Temperature Coefficient (NTC) behavior above 70°C, leading to safety risks such as self-burning, and previous methods to reduce this effect either require costly cross-linking or only partially eliminate the NTC effect.
Innovation Solution
A screen-printable PTC ink composition with double switching temperatures is developed, using two types of polymers with different melting or softening points to maintain PTC behavior across a wider temperature range, eliminating the NTC effect by incorporating 10-30 wt% conductive particles, 5-15 wt% each of crystalline and non-crystalline polymer resins, 40-80 wt% organic solvent, and 0-5 wt% additives, and applying a specific preparation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cross-linking is used to eliminate the NTC effect, then the PTC composition becomes safer, but the production time and costs increase
Solution Approach 1:
The invention changes the chemical composition parameters by introducing a specific polymeric additive with controlled melting/softening temperature into the PTC composition. This additive modifies the thermal behavior of the polymer matrix to eliminate the NTC effect without requiring cross-linking, thus maintaining safety while avoiding the time and cost penalties of cross-linking processes.
Solution Approach 2:
The invention extracts and eliminates the harmful NTC behavior from the PTC composition by carefully selecting polymer and additive combinations that prevent the formation of the NTC region entirely, rather than trying to manage or mitigate it after it appears.
2Reliability
If cross-linking is used to eliminate the NTC effect, then the PTC composition becomes safer, but the production costs increase
Solution Approach 1:
The invention changes the compositional parameters by incorporating a polymeric additive with specific properties (melting/softening temperature greater than the base resin) that eliminates the NTC effect through compositional modification rather than requiring expensive cross-linking processes, thereby reducing production costs while maintaining safety.
3Device complexity
If a single polymer is used in the PTC composition, then the formulation is simpler, but the NTC effect cannot be completely eliminated
Solution Approach 1:
The invention creates a composite polymeric system by combining a base polymer resin with a specifically selected polymeric additive. This composite formulation leverages the different thermal properties of the two polymers to eliminate the NTC effect, achieving superior safety performance through material composition rather than complex processing or additional components.
4Stability of the object's composition
If the temperature exceeds the melting point of the polymer, then the PTC composition becomes unstable, but using higher melting point polymers limits the working temperature range
Solution Approach 1:
The invention optimizes the thermal parameters by selecting a polymeric additive with a melting/softening temperature specifically greater than that of the base resin. This parameter selection ensures that the additive remains stable and effective across the entire working temperature range, preventing NTC behavior at elevated temperatures while maintaining PTC functionality at lower temperatures.
Solution Approach 2:
The invention applies different functional properties to different temperature ranges: the base polymer provides PTC behavior at lower temperatures, while the polymeric additive with higher melting point provides thermal stability and NTC elimination at higher temperatures. This local quality approach allows the composition to be optimized for different thermal regimes simultaneously.
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 PTC ink composition provides stable PTC behavior below and above 70°C, eliminating safety risks by maintaining high PTC ratios throughout the temperature range, ensuring reliable performance in self-regulating heating elements without the NTC-induced safety hazards.
Implementation Method 1
PTC means positive temperature coefficient, which refers to materials that experience an increase in electrical resistance when their temperature is raised
Implementation Method 2
two types of polymers with different melting or softening points to maintain PTC behavior across a wider temperature range
Implementation Method 3
two types of polymers with different melting or softening points
Data Source
AI summary
The invention provides an electrically conductive screen-printable PTC ink with double switching temperatures, which comprising by weight based on total composition, 10-30 wt % conductive particles; 5-15 wt % polymer resin 1; 5-15 wt % polymer resin 2; 40-80 wt % organic solvent; e) 1-5 wt % other additives.