Magnesium hydroxide flame retardant and flame retardant polymer for cables

Abstract

The invention relates to improvements of a magnesium hydroxide flame retardant and a flame retardant polymer for cables. Natural magnesium hydroxide with the Mg(OH)2 content being not smaller than 96wt percent is adopted, and micro powder with a mean grain size of 0.5-1 micrometer is obtained through physical ultrafine grinding and grading; then 0.8-3wt percent of coupling agent is added, and an obtained mixture is stirred at a high speed, sufficiently mixed and then subjected to secondary surface processing by high-pressure airflows in a jet mill so as to obtain the magnesium hydroxide flameretardant with good smoothness and basically no aggregates; and the magnesium hydroxide flame retardant can smoothly flow like vegetable seeds under pushing by external forces. A polyolefin flame retardant polymer for cables is prepared from the following components in parts by weight: 100 parts of polyolefin, 100-150 parts of submicron scale magnesium hydroxide, 2-10 parts of oxosilane, 0.2-1 part of antioxygen, 1-10 parts of processing aid and 0-6 parts of functional aid. The flame retardant polymer for cables has the following parameters: the oxygen index (OI) is up to 36-42, the tensile strength is not smaller than 10Mpa, the breaking elongation rate is not smaller than 200 percent, and the volume resistivity is not smaller than 10*1,015. The cracking resistance of the flame retardant polymer for cables is good, and the flame retardant polymer for cables cannot crack within one hour at a temperature of 130 DEG C and exceed the standard of the JB10707-2007 low-smoke non-halogen flame-retardant cable material. The flame retardant polymer for cables has good extrusion manufacturability and wide extrusion temperature range and can be effectively extruded at a temperature of 165-190 DEG C. The extrusion torque is small and reduced by 30 percent, thus the flame retardant polymer for cables can be smoothly extruded out by original equipment without a special screw rod.

Description

technical field [0001] The invention relates to an improved magnesium hydroxide flame retardant and a flame retardant polymer for cables with excellent flame retardant properties and good mechanical properties. Background technique [0002] Aluminum hydroxide is a low-smoke and halogen-free flame retardant commonly used in polyolefin cables, and is widely used in cable insulation and cable sheathing. However, due to the relatively low decomposition temperature of aluminum hydroxide (220°C), the extrusion temperature of cable insulation / sheathing polyolefin is mostly 160-180°C, sometimes exceeding 190°C. At this extrusion temperature, aluminum hydroxide has been heated and vaporized. Not only does the extruded material easily produce pores, which affects the electrical performance, mechanical strength, and surface quality, but also the thermal vaporization also makes the smelly hot gas come out, which deteriorates the production environment. At the same time, in order to imp...

AI Technical Summary

Problems solved by technology

The performance fluctuates greatly, the stability is poor, and the mechanical properties cannot meet the requirements of cable materials, and most of the flame retardant oxygen index cannot meet the requirements, especially the low elongation at break, which is far from the standard requirements of cable materials, indicating that the modification Compatibility and dispersion are still not ideal

[0007] The above-mentioned various surface properties of magnesium hydroxide are improved, and the performance of the cable fuel resistance is still not ideal, and its shortcomings still have room for improvement.