Novel positive-temperature-coefficient thermistor element core layer material and application thereof

Abstract

The invention relates to the field of thermistors, and particularly relates to a positive-temperature-coefficient thermistor element core material and a preparation method thereof. The positive-temperature-coefficient thermistor element core material disclosed by the invention is prepared from the following raw material constituents: 41-54wt% of a polymer base material and 46-59 wt% of a conductive filler; the polymer base material is formed by mixing a graft polymer with a high melt flow rate with a graft polymer with a low melt flow rate; and the graft polymer is selected from one or the combination of more than two of graft polyolefin, graft polyolefin copolymer and graft polyolefin derivative, and the graft group of the graft polymer is a polar group. According to the invention, by using two types of maleic anhydride-grafted high-density polypropylene with different melt flow rates together, processing performance can be improved, room-temperature resistivity can be reduced and production efficiency can be increased; and the two types of maleic anhydride-grafted high-density polypropylene is prepared into an annular positive-temperature-coefficient thermistor element which is good in electrical performance, high in PTC (positive-temperature-coefficient) strength and the like.

Description

technical field [0001] The invention relates to the field of thermistors, in particular to a core layer material of a positive temperature coefficient thermistor element and an application thereof. Background technique [0002] Positive temperature coefficient (positive temperature coefficient, PTC) material means that its resistivity will increase with the increase of temperature. Conductive polymer materials exhibiting PTC behavior can be used in circuit protection components, and such conductive polymer materials generally include polymer components and conductive fillers dispersed therein. Compositions with low resistivity are suitable for circuit protection elements that respond to changes in room temperature or current conditions. Under normal conditions, circuit protection elements in series with a load in a circuit remain at a low temperature and low resistance. But when exposed to overcurrent or overheating conditions, the resistance of the element increases, effec...

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Problems solved by technology

[0003] To obtain low resistance is mainly by increasing the area of ​​the component or increasing the content of conductive filler in the conductive composite material, but the area of ​​the component is increased, occupying a large space on the circuit board, and the thermal performance is not ideal

The addition of conductive fillers will affect the processability of conductive composites, reduce the strength of PTC, that is, reduce the range where the resistivity of conductive composites increases in response to temperature rise

[0004] The introduction of a compatibilizer maleic anhydride grafted polyethylene with polar groups in the conductive composite material increases the interface compatibility of the composite material; due to the low melt flow rate grafted high-density polyethylene, the processing is easy, However, it is difficult to achieve low resistivity, and when low resistivity is achieved, the electrical properties and PTC strength become worse

The maleic anhydride grafted high-density polyethylene with high melt flow rate can easily achieve lower resistivity, but it is difficult to process, and it is easy to stick to the roll during the calendering process, which affects production efficiency, etc.

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