Thermoplastic Polyimide Insulated Wire With Low-Bubble Extrusion
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Solution Overview
Problem
The production of insulated wires using thermoplastic polyimide (TPI) is inefficient and prone to bubble formation due to poor thermal stability, leading to reduced breakdown voltage and shortened service life.
Innovation Solution
A method involving a bonding layer formation using a specific mixed liquid of polyamide-imide, polyimide, and organic solvent, followed by extrusion of TPI under controlled negative pressure and preheating conditions to form a thermoplastic polyimide insulating layer, minimizing bubble formation and improving adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the one-time extrusion process is used to improve production efficiency, then productivity is improved, but bubbles are easily generated in the insulating layer due to poor thermal stability of thermoplastic polyimide, reducing breakdown voltage
Solution Approach 1:
The patent applies preliminary action by pre-heating the conductor core before extrusion and performing vacuum treatment on the extruder to remove moisture and gases from the thermoplastic polyimide particles. This preliminary preparation prevents bubble formation during the extrusion process, allowing one-time extrusion to produce high-quality insulating layers without compromising breakdown voltage while maintaining high production efficiency
Solution Approach 2:
The patent changes key process parameters including setting the extrusion temperature between 370-410°C, pre-heating temperature between 200-320°C, and applying vacuum pressure ≥0.3 MPa. These parameter optimizations enable the thermoplastic polyimide to be extruded without bubble formation, resolving the contradiction between production efficiency and insulating layer quality
2Strength
If multiple times of coating and curing is used to form the insulating layer, then adhesion is improved, but the operation becomes cumbersome and production efficiency decreases
Solution Approach 1:
The patent merges the conductor core and insulating layer formation into a one-time extrusion process. By optimizing the extrusion parameters and applying preliminary vacuum treatment, the process achieves both good adhesion (through proper bonding layer formation) and high production efficiency (by eliminating multiple coating and curing cycles), thus resolving the contradiction between adhesion strength and productivity
3Strength
If multiple times of baking is performed to cure the insulating layer, then adhesion is improved, but aging occurs and adhesion decreases
Solution Approach 1:
The patent skips the traditional multiple-baking curing process by using a one-time extrusion method with optimized temperature and vacuum parameters. This approach rapidly forms a high-quality insulating layer without subjecting it to repeated thermal cycling that causes aging, thereby maintaining adhesion strength and extending service life
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 method significantly reduces bubble content and size in the insulating layer, enhancing breakdown voltage and service life of the insulated wire.
Implementation Method 1
vacuuming an extruder, and melting and extruding the thermoplastic polyimide at an outer side of the core material after preheating, so as to form a thermoplastic polyimide insulating layer, wherein the extruding process is carried out under a negative pressure condition; and a vacuum suction for applying the negative pressure is controlled to be larger than or equal to 0.3 MPa
Implementation Method 2
a preheating temperature is controlled to be 200 °C-320 °C; and an extruding temperature is 370 °C-410 °C
Implementation Method 3
melting and extruding the thermoplastic polyimide at an outer side of the core material after preheating, so as to form a thermoplastic polyimide insulating layer
Data Source
Figure 1
AI summary
The present invention discloses an insulated wire and a preparation method therefor, a coil, and an electronic/electrical device, and relates to the technical field of electrochemical components. In the preparation method provided by the present invention, the thermoplastic polyimide is extruded to mold by adopting the extrusion process, so as to form the insulating layer on the core material, which can significantly improve the production efficiency compared to the traditional multiple-time coating process. The preparation process of the bonding layer and the extrusion process are optimized; the bonding layer is prepared by a specific bonding layer formulation; and then the insulating layer is extruded under a specific negative pressure, so that the prepared thermoplastic polyimide insulating layer has fewer bubbles, and the size of the bubbles is smaller, which ensures the insulating layer to have a higher breakdown voltage.