Composite material for thermistor and preparing method thereof

Abstract

The invention discloses a composite material for a thermistor and a preparing method thereof. The composite material is prepared from, by weight, 80-90 parts of high-density polyethylene, 25-35 parts of ethylene-vinyl acetate copolymer, 10-20 parts of polytetrafluoroethylene, 5-15 parts of polyvinylpyrrolidone, 25-35 parts of conductive filler, 6-8 parts of coupling agent, 3-5 parts of crosslinking agent, 1-3 parts of antioxidant and 2-4 parts of lubricant. The conductive filler is a mixture of titanium diboride and carbon fiber by the weight ratio of (6-10):1; the coupling agent is isobutyl triethoxy silane; the crosslinking agent is trimethylolpropane triacrylate. A positive-temperature-coefficient thermistor made of the composite material for the thermistor is low in room temperature electrical resistivity and high in PTC strength, after circulation for 100 times, the change rate of room temperature electrical resistivity and PTC strength is small, and the composite material has low room temperature, high PTC electrical resistivity and stability.

Description

technical field [0001] The invention belongs to the field of composite materials, and in particular relates to a composite material for a thermistor and a preparation method thereof. Background technique [0002] Polymer composite materials with a positive temperature coefficient (PTC) are widely used in computers and their peripheral equipment, mobile phones, battery packs, telecommunication and network equipment, transformers, industrial control equipment, automobiles and other electronic products to play a role in overcurrent Or the role of over-temperature protection. PTC polymer composite material is a heat-sensitive material whose resistance value increases with the increase of temperature, that is, the resistance or resistivity of the material remains basically unchanged or only slightly changes within a certain temperature range, while When the temperature reaches a specific transition point temperature of the material, the resistivity of the material will undergo a...

AI Technical Summary

Problems solved by technology

The PTC polymer composite material filled with carbon black has the characteristics of adjustable electrical conductivity in a wide range, easy molding, and low cost; however, the existing problems are high room temperature resistivity and poor stability of the PTC effect, resulting in PTC strength and output. The power attenuation is too fast, the leakage current is large after protection, etc.

However, in the PTC polymer composite material with metal particles as conductive fillers, since the metal particles are always rigid particles during the phase transition process of PTC temperature rise, no phase transition occurs, resulting in a more serious negative temperature resistance effect (NTC) during the continuous temperature rise process. ;The emergence of NTC phenomenon not only causes irreversible changes in the electrical properties of PTC materials, but also causes failure due to high temperature of the materials during the use of the materials, and even ignites and burns