Polyamide 610 Battery Gasket Injection Molding
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Solution Overview
Problem
Alkaline batteries face issues with surface wrinkles in the thin wall portion of the gasket, leading to premature failure and liquid leakage due to the use of high molecular weight polyamide resins, which are prone to carbide generation and degradation, affecting the battery's lifetime.
Innovation Solution
A polyamide 610 resin composition with a viscosity number ranging from 80 ml/g to 145 ml/g is used, combined with a crystal nucleating agent and a release agent, and injection molded at a temperature between 250°C to 280°C to prevent carbide generation and ensure excellent fluidity, allowing for the production of gaskets with improved mechanical properties and extended battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyamide resin having a high molecular weight is used to improve resistance to alkaline electrolytic solution, then the gasket can be suppressed to be deteriorated due to electrolytic solution, but the resin is poor in fluidity during injection molding, causing surface wrinkles to occur in the thin wall portion
Solution Approach 1:
The patent changes the viscosity number parameter of the polyamide 610 resin from conventional high values (>150 ml/g) to a specific range of 80-145 ml/g. This parameter optimization maintains the resin's resistance to alkaline electrolytic solution while significantly improving its fluidity during injection molding, thereby preventing surface wrinkles in the thin wall portion without sacrificing reliability.
2Manufacturing precision
If the melting temperature of the polyamide resin composition is increased to improve the fluidity of the resin, then the surface wrinkles can be eliminated, but the degradation of the polyamide resin composition is accelerated and generation of carbides becomes noticeable
Solution Approach 1:
The patent changes the viscosity number parameter to achieve optimal fluidity at lower processing temperatures. By selecting polyamide 610 resin with viscosity number of 80-145 ml/g, the resin achieves sufficient fluidity for proper filling of thin wall portions at temperatures of 230-280°C, preventing carbide generation that would occur at higher temperatures required for high viscosity resins.
3Manufacturing precision
If the viscosity number of the polyamide 610 resin is decreased to improve fluidity, then surface wrinkles are prevented, but the mechanical properties of the gasket may be compromised
Solution Approach 1:
The patent identifies and applies a specific viscosity number range of 80-145 ml/g for polyamide 610 resin. This optimized range provides the optimal balance between fluidity and mechanical properties - the resin flows sufficiently to fill thin wall portions without surface wrinkles while maintaining adequate mechanical strength and durability for gasket application.
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 prevents surface wrinkles and carbide formation, ensuring the gasket's explosion-proof safety valve operates correctly until the battery's lifetime is reached, thereby prolonging the battery's lifespan and maintaining mechanical integrity.
Implementation Method 1
injection molded at a temperature between 250°C to 280°C to prevent carbide generation and ensure excellent fluidity
Data Source
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AI summary
The present invention provides a gasket for an alkaline battery which enables such a long lifetime that liquid leakage due to carbides of a polyamide resin raw material does not occur, surface wrinkles are hardly generated because of excellent fluidity during molding, and a thin wall portion serving as an explosion-proof safety valve can be normally ruptured until the lifetime of an alkaline battery expires, and a method for manufacturing the same. The gasket for an alkaline battery is formed by injection molding a resin composition, and has a thin wall portion in part. The resin composition is a polyamide 610 resin composition containing a polyamide 610 resin as a main component and a molding aid such as a release agent and a crystal nucleating agent, the polyamide 610 resin having a viscosity number in a range of 80 ml/g or more and 145 ml/g or less.