Method for preparing high-stability PPTC based on montmorillonite modified tungsten carbide

By using mechanical mixing and vacuum drying, a dual-defense system was constructed by blending montmorillonite-modified tungsten carbide powder with polyvinylidene fluoride (PVDF). This solved the problem of rapid oxidation rate of tungsten carbide powder in humid environments and achieved high stability and electrical resistance stability of PPTC.

CN121687664BActive Publication Date: 2026-05-26SOUTHWEST PETROLEUM UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
SOUTHWEST PETROLEUM UNIV
Filing Date
2026-02-10
Publication Date
2026-05-26

AI Technical Summary

Technical Problem

In the prior art, the oxidation rate of tungsten carbide powder is accelerated in a humid environment, which leads to an increase in the resistance of the prepared PPTC and instability in use, especially in high temperature and high humidity environments where the performance deteriorates.

Method used

By mechanically mixing and grinding montmorillonite powder and tungsten carbide powder to form a mixed modified powder, followed by vacuum drying, and finally blending with polyvinylidene fluoride, a dual defense system is constructed to inhibit the oxidation of tungsten carbide.

Benefits of technology

It effectively inhibits the oxidation of tungsten carbide, improves the stability and resistance consistency of PPTC in humid environments, and meets the requirements for use in high temperature and high humidity environments.

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Abstract

This invention discloses a method for preparing highly stable PPTC based on montmorillonite-modified tungsten carbide, belonging to the field of high-stability device fabrication technology. First, montmorillonite and tungsten carbide are ground to obtain a mixed modified powder. The mixed modified powder is then dried in a vacuum drying oven to obtain composite modified tungsten carbide powder. Finally, PPTC is prepared by blending the composite modified tungsten carbide powder with polyvinylidene fluoride (PVDF). This invention uses montmorillonite to modify tungsten carbide. Montmorillonite has numerous interlayer voids and surface hydroxyl groups, which can form van der Waals forces, hydrogen bonds, and electrostatic interactions with the hydroxyl groups on the tungsten carbide surface, shielding the hydroxyl groups and reducing water absorption by the tungsten carbide. Simultaneously, montmorillonite can adsorb water molecules in the microenvironment, providing a dry microenvironment for the tungsten carbide and inhibiting the oxidation of tungsten carbide in the PVDF matrix, thus preparing highly stable PPTC.
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