Bonded Magnet Resin Composition for Higher Magnetization
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Solution Overview
Problem
Molded articles from resin compositions using polyamide 6 for bonded magnets exhibit insufficient magnetization.
Innovation Solution
A resin composition utilizing a xylylenediamine-based polyamide resin with diamine-derived structural units from xylylenediamine and dicarboxylic acid-derived structural units from α,ω-linear aliphatic dicarboxylic acids, combined with a magnetic material like ferrite or rare earth magnets, to enhance magnetization and maintain chemical resistance and low water absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polyamide 6 is used as the resin binder, then excellent fluidity and crystallinity are achieved, but magnetization is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the polyamide resin by introducing xylylenediamine-derived structural units (70-100 mol%) combined with aliphatic dicarboxylic acid units (30-70 mol%). This compositional parameter change maintains the resin's fluidity while improving magnetization properties, resolving the contradiction between processing fluidity and magnetic performance
Solution Approach 2:
The patent creates a composite resin system by combining xylylenediamine-based polyamide with specific aliphatic dicarboxylic acids (adipic, sebacic, dodecanedioic acid). This composite approach integrates the fluidity benefits of polyamide 6 with enhanced magnetization capabilities, achieving both excellent fluidity and sufficient magnetization in the bonded magnet
2Reliability
If xylylenediamine-based polyamide resin is used, then magnetization is improved, but water absorption may increase
Solution Approach 1:
The patent carefully selects the dicarboxylic acid component parameters (C4-C12 aliphatic acids) to balance magnetization improvement with water absorption control. By optimizing the chain length and structure of the dicarboxylic acid units, the resin achieves high magnetization while maintaining low water absorption characteristics
Solution Approach 2:
The patent introduces aromatic ring structures from xylylenediamine units at specific positions within the polymer chain (70-100 mol%). These aromatic segments provide hydrophobic character that reduces water absorption, while the overall polyamide structure maintains magnetization capability, creating local quality differentiation within the resin matrix
Data Source
AI summary
Provided are a resin composition capable of providing a molded article excellent in magnetization, and a molded article formed from the resin composition. The resin composition for a bonded magnet contains from 10 to 90 parts by mass of a polyamide resin and from 90 to 10 parts by mass of a magnetic material. The polyamide resin contains a xylylenediamine-based polyamide resin. The xylylenediamine-based polyamide resin contains diamine-derived structural units and dicarboxylic acid-derived structural units. 70 mol % or more of the diamine-derived structural units are derived from a xylylenediamine. 70 mol % or more of the dicarboxylic acid-derived structural units are derived from an α,ω-linear aliphatic dicarboxylic acid having from 4 to 12 carbon atoms.