Silane crosslinked flame-retardant semiconductive polyolefin sheathing material, preparation method therefor and application of sheathing material

Abstract

The invention discloses a silane crosslinked flame-retardant semiconductive polyolefin sheathing material, a preparation method therefor and an application of the sheathing material. The sheathing material comprises a raw material A and a raw material B, wherein the raw material A comprises linear low-density polyethylene, an ethylene-vinyl acetate copolymer, an ethylene-octylene copolymer, a flame retardant, conductive carbon black, vinyl-containing silane, an initiator and a pre-crosslinking resisting agent, and the raw material B comprises linear low-density polyethylene and a hydrolyst; and the pre-crosslinking resisting agent is prepared through subjecting 2-vinyl-1H-benzimidazole and 3-phenyl-2-methyl-2-acryl propionate to copolymerization. The preparation method comprises the stepsof preparing the silane grafted raw material A, then, mixing the silane grafted raw material A with the raw material B according to a formula, carrying out extrusion molding, and then, carrying out water-cooking crosslinking, thereby preparing the sheathing material. The invention further discloses a coal-mine gas exhaust pipe containing the above-mentioned material. The sheathing material disclosed by the invention not only has good electric conductivity and flame retardancy, but also has the characteristics of excellent mechanical properties, high-temperature resistance, long service life and the like.

Description

Technical field [0001] The invention belongs to the field of coal mines, and particularly relates to materials for coal mine gas pipes, in particular to a silane cross-linked flame-retardant semi-conductive polyolefin sheath material and a preparation method and application thereof. Background technique [0002] In coal mine production, mine operations are very dangerous. One of the main sources of hazard is the gas produced. Therefore, the gas needs to be discharged. However, in the process of drainage, the main body of the gas flowing in the discharge pipeline is , And mixed with a certain amount of dust, these air streams with solid dust are in the pipeline (most of the polyolefin plastic pipes currently used are widely used because of their light weight, corrosion resistance, aging resistance, easy installation, etc.) When the gas and solid dust flow at a certain speed, the gas and solid dust will frequently rub and collide with the tube wall, resulting in strong static elect...

AI Technical Summary

Problems solved by technology

[0002] In coal mine production, mine operations are very dangerous, and one of the main sources of danger is the gas generated, so it is necessary to discharge the gas. However, during the drainage process, the substance flowing in the discharge pipeline is mainly the main , and mixed with a certain amount of dust, these airflows with solid dust are in the pipeline (most of the polyolefin plastic pipes currently used are widely used because of their light weight, corrosion resistance, aging resistance, and easy installation) When the gas flows at a certain speed, the gas and solid dust will frequently rub and collide with the pipe wall, thereby generating strong static electricity, and even accompanied by spark discharge, the energy of the discharge spark is enough to ignite the gas, which is easy to cause fire or Gas explosions caused mine accidents. Although some improvements have been made to the discharge pipelines on the market, such as adding antistatic agents to reduce the possibility of static electricity, the effect is not ideal and there are great potential safety risks.

[0003] At present, there is a solution to achieve the volume resistivity of the material less than 100Ω·cm by adding conductive carbon black, which can quickly lead to static electricity, but it is basically a thermoplastic polyolefin sheath material, such as the Chinese invention patent CN109082002A, which discloses a coal mine gas Flame-retardant semi-conductive sheath material for pipes and its preparation method and application. Although this patent realizes the excellent electrical conductivity and flame retardancy of the sheath material, it still has certain defects in high temperature resistance and service life. In the prior art Cross-linking methods are usually used to obtain cross-linked polyolefin materials, such as silane cross-linking methods, and then increase the working temperature of polyolefin materials. However, this method is prone to pre-crosslinking during extrusion, mixing or storage. , The reasons generally include: nitrogen-phosphorus flame retardants are easy to absorb moisture, resin materials or other raw materials contain bound water or free water, etc., which not only affect the mechanical properties of the product, but also the rough extrusion surface of the product seriously affects The quality and processing performance of the product are affected, and the product may even be scrapped, which is not conducive to the application in high-strength environments.

[0004] In view of the problem of pre-crosslinking in the above-mentioned cross-linked polyolefin materials, adding anti-pre-crosslinking agents is a common practice in the prior art. Commonly used anti-pre-crosslinking agents include long-chain silanes or substituted silanes, such as hexadecyl Trimethoxysilane or 3-thiooctanoyl-1-propyltriethoxysilane, using its easy hydrolysis and condensation characteristics, is used for waterproofing of products; such as styrene, aniline, caprolactam, caprolactate, etc. Anti-pre-crosslinking agents, however, practical research has found that although these anti-pre-crosslinking agents can achieve a certain anti-pre-crosslinking effect, but for coal mine flame-retardant semi-conductive polyolefin sheath materials containing a large amount of conductive carbon black, The above-mentioned existing anti-pre-crosslinking agents are difficult to achieve anti-pre-crosslinking and at the same time, the material has excellent mechanical properties, flame retardant and electrical conductivity, and it is difficult to meet the high safety requirements of coal mine operations.

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