Polycarbonate Battery Pack Resin for Low-Temperature Impact Strength
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Solution Overview
Problem
Battery packs face challenges in maintaining drop impact strength, flame retardancy, and heat resistance, especially under low-temperature environments, due to limitations in existing resin compositions and manufacturing processes like ultrasonic welding, which can create notches that lead to structural weaknesses.
Innovation Solution
A polycarbonate resin composition is developed, incorporating a polycarbonate-polyorganosiloxane copolymer with a specific structural unit and an aromatic polycarbonate, along with a phosphorus-based antioxidant, an alkali metal salt, and a mixed powder of polytetrafluoroethylene particles and organic polymer particles, to enhance drop impact strength, flame retardancy, and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional resin compositions are used to maintain flame retardancy and heat resistance, then these properties are preserved, but drop impact strength under low-temperature environment deteriorates
Solution Approach 1:
The patent uses a composite resin composition containing polycarbonate, polyorganosiloxane copolymer, and phosphate-based flame retardant. This composite structure allows the material to simultaneously achieve low-temperature impact strength (through polycarbonate-polyorganosiloxane copolymer) and flame retardancy (through phosphate-based flame retardant), resolving the contradiction between strength and reliability.
Solution Approach 2:
The patent changes the chemical composition parameters of the resin by incorporating specific ratios of polycarbonate (5-95 parts), polyorganosiloxane copolymer (5-95 parts), and phosphate-based flame retardant (0.1-10 parts). This parameter optimization enables the material to maintain both low-temperature impact resistance and flame retardancy properties simultaneously.
2Productivity
If ultrasonic welding is used to bond battery pack cases, then manufacturing efficiency is improved, but notches and burrs are produced that create structural weaknesses
Solution Approach 1:
The patent converts the harmful effect of ultrasonic welding (notch formation) into a beneficial outcome by using phosphate-based flame retardant that reduces burr generation. The flame retardant components modify the welding process to produce fewer burrs, thereby reducing notch formation while maintaining the efficiency of ultrasonic welding.
Solution Approach 2:
The patent introduces phosphate-based flame retardant as an intermediary substance that mediates between the ultrasonic welding process and the resin material. This intermediary reduces the harmful effects of ultrasonic welding (burr and notch formation) while maintaining manufacturing efficiency, acting as a buffer between the welding energy and the material structure.
Data Source
Figure 1~3
AI summary
A polycarbonate resin composition for a battery pack, which comprises: 100 parts by mass of (A) a polycarbonate-based resin composed of 5 to 100 mass% of a polycarbonate-polyorganosiloxane copolymer (A-1) whose main chain is formed of a structural unit represented by the general formula (I) and a structural unit represented by the general formula (II), and that contains 2 to 10 mass% of a polyorganosiloxane block, and 0 to 95 mass% of an aromatic polycarbonate (A-2) except the copolymer (A-1); and 0.01 to 1 parts by mass of (B) a phosphorus-based antioxidant; and a battery pack formed by using the resin composition.