Research progress of the hottest antistatic polyol

2022-10-02
  • Detail

Research progress of antistatic polyolefin composites

polyolefin has become the largest share of synthetic materials in the world today. Polyolefin resin has excellent performance and low price, and is widely used in all fields of national economy and people's life. Its production capacity and demand mark a country's petrochemical industry level and people's living standard. Polyolefin plastics have excellent insulation properties, such as PP and PE, whose volume resistivity is generally 1017 ~ 1019 Ω/cm, but sometimes their insulation will encounter trouble in many occasions, and even cause great losses, such as electric shock when manufacturing PE and BOPP films. Plastic products are easy to dust, which will reduce the use value. Electrostatic sparks can also cause major accidents such as explosion and fire. Therefore, how to eliminate and reduce the electrostatic hazards of polyolefin plastics and their products has become an important technical issue that needs to be solved urgently in the field of polymer materials. [1] In view of the electrostatic problem in the process of polyolefin processing and use, antistatic agents and other corresponding additives or fillers are mostly used to reduce the accumulated electrostatic amount. It can also be used to test the bursting strength of non paper materials such as silk and cotton cloth, so that the comprehensive performance of products can achieve a relatively ideal effect. By analyzing the antistatic mechanism of polymer materials, this paper describes the research progress and prospects of antistatic polyolefins

anti static principle

insulator is easy to generate electrostatic charge in dry air due to friction, which causes great harm to processing and use. In essence, the way to prevent electrostatic hazards is to reduce or prevent friction to reduce the generation of electrostatic charges, or make electrostatic charges leak out quickly through various ways. At 20 ℃, the ρ If s is lower than 1010 Ω, it can be considered that the polymer has good antistatic performance: if ρ S = 1010 ~ 1012 Ω, it can be considered that the polymer has good antistatic performance; When ρ S = 1012-1014 Ω, it can be considered that the polymer has moderate antistatic effect; When ρ S = 1014 ~ 1015 Ω, only a very weak antistatic effect; When ρ When s is higher than 1015 Ω, it is considered that there is no antistatic effect. [2] At present, the processing methods of antistatic polyolefin composites mainly include adding conductive filler, adding antistatic agent and blending with structural conductive polymer materials

1.1 adding conductive filler method

this method is to add inorganic conductive filler into polyolefin material matrix. At present, carbon black filling is the most widely used, because carbon black raw materials are easy to obtain, cheap, durable and stable conductivity, and can also greatly adjust the conductivity. The volume resistance of carbon black itself is between 0.1 ~ 10.2 Ω, which is a natural semiconductor. In the resin composite, when the carbon black particles contact with each other to form a complex or the gap between carbon black particles is several 10 ~ 10m, a conductive path can be formed [3]. Therefore, the composite antistatic polymer material filled with carbon black is a kind of antistatic material with wide application and large amount at present. Metal fillers can also be used, mainly including metal powders (AG, Cu, Al, Ni, etc.), metal fibers (copper fiber, aluminum fiber, stainless steel fiber, alloy fiber, etc.) and metal oxides

1.2 add antistatic agent

the action mechanism of antistatic agent [4] is to form a conductive layer on the surface of the material, reduce its surface resistivity, make the generated electrostatic charge leak rapidly, endow the surface of the material with certain lubricity, reduce the friction coefficient, and inhibit and reduce the generation of electrostatic charge. Therefore, the polarity of the antistatic agent, its compatibility with the substrate and its dispersion in the material all affect the antistatic effect. Antistatic agents can be divided into cationic, anionic, amphoteric, non-ionic and polymeric types according to whether the hydrophilic group in the molecule can be ionized and ionized. Table 1 lists the types of antistatic agents and their applicable resins. [5] Generally, the antistatic agent should have a certain compatibility with the matrix, but the Japanese fixture should not be too strong; Ionic antistatic agents should be selected for polar substrates, while non-ionic antistatic agents are more suitable for weak polar or non-polar polymers. Table 1 main types of antistatic agents

1.3 blend with structural conductive polymer materials

this kind of structural conductive polymer materials mainly include conjugated polymers such as polyaniline, polyacetylene, polypyridine, polyphenylene, polythiophene, Polyquinoline, polyphenylene sulfide, etc. due to the conjugated double bonds in the structure, π electrons can move freely on the molecular chain, and the carrier mobility is very high. Therefore, this kind of material has high conductivity. Fundamentally speaking, this kind of conductive polymer material itself can be used as antistatic material, but because this kind of polymer is generally rigid, insoluble, difficult to form, easy to oxidize and poor stability, it cannot be directly used alone. It is generally used as conductive filler to blend with other polymer matrix to make antistatic composite materials. This kind of structural conductive polymer material has good compatibility with polymer materials, The effect is better and more lasting

research on improving the performance of antistatic polyolefin composites

2.1 research on antistatic polyolefin composites with conductive fillers

adding conductive fillers has high application value in the research of antistatic polyolefin composites, and many materials made by this method have been commercialized. Carbon fillers and metal fillers are mainly used in this method

2.1.1 carbon fillers

mainly include carbon black, graphite, carbon fiber and carbon tube. This kind of filler is most widely used because of its low price and stable performance, but it also has the disadvantages of dark color and poor adjustability. However, it is still a kind of filler with wide application and large amount.. Liu Fang [6] studied the antistatic modification of HDPE based resin with antistatic agent and conductive carbon black respectively. The results showed that the composite materials obtained by using the formula of composite antistatic agent containing polar ethylene copolymer or conductive carbon black containing chlorinated polyethylene elastomer had better antistatic and physical properties. Expanded graphite also has good antistatic effect. Yang Yongfang [7] and others studied the mechanical and electrical properties of polyethylene and expanded graphite composites by solution intercalation method. The results show that the volume resistance of the composite decreases to 1 when the content of expanded graphite is 10 ~ 15 parts × Below 108 Ω/cm. At present, using carbon black to prepare nano dispersed antistatic composites is an important development trend. When carbon black is dispersed in the polymer at the nanometer level, the anti electric part of the material can be greatly improved, including the electrostatic performance and comprehensive performance of the load measurement system and the displacement measurement system. Zhangyumei et al. [8] prepared conductive carbon black (CB) filled UHMWPE antistatic composites. The experimental results showed that the carbon black percolation zone content in the uhmwpe/cb composite system modified by solid-phase surface grafting was 5% - 7%, and the surface resistance decreased from 1014 Ω to 107 Ω. The low carbon content ensured the excellent wear resistance of the composite. At the same time, SEM characterization proved that CB reached nano dispersion in the modified UHMWPE, A double nano conductive complex structure is formed, which improves the antistatic, mechanical and thermal deformation properties of the composite

2.1.2 metal fillers

in recent years, antistatic composites prepared with metal fillers have also made great progress. When metal powder is filled, there are many disadvantages, such as large amount of addition, easy thermal oxidation and catalytic effect on matrix aging. Metal fiber fillers are easy to break and oxidize during processing, and the price is also high. These disadvantages restrict their further application in antistatic composites. The newly developed zinc oxide whisker (ZnOw) has a unique three-dimensional four needle structure and unique semiconductor properties, and is considered to be an antistatic filler with excellent performance. Using zinc oxide whisker (ZnOw) as antistatic agent has the advantages of less addition, stable and lasting effect, isotropy and adjustable color. It has a broad prospect in the application of antistatic polyolefin composites. Ma Feng and others [9] used zinc oxide whisker as a conductive additive to improve the antistatic performance of polypropylene flame retardant composite system. It was found that when the content of zinc oxide whisker was 10% - 12%, the surface resistivity and friction static voltage of the composite decreased to about 109 Ω and 250V respectively. It showed that the additive could make polypropylene obtain good antistatic performance and be compatible with flame retardant materials. It is considered that the micro mechanism of zinc oxide whiskers improving the conductivity of the composite system can be attributed to the effects of complex conductivity, tunneling effect and tip discharge. Polyolefin antistatic composites prepared by filling with nano metal oxides have also achieved good results. Zhang Jiemin and other [10] people used nano SnO and ZnO as conductive fillers to add to polyolefin materials, discussed the micro mechanism of metal oxide nanoparticles to improve the conductivity and flame retardance of polymers, analyzed the appropriate balance and compatibility of the dispersion and agglomeration ability of nanoparticles in polymers, formulated the anti-dumping litigation route against aluminum in the main non-ferrous industries, and made progress in research work

2.2 research on antistatic polyolefin composites with antistatic agents

antistatic agents are mainly a kind of surfactant substances, which can be divided into external antistatic agents and internal antistatic agents according to the way of use. The basic requirements of external antistatic agent are that it is firmly combined on the surface of resin, has good antistatic effect, adapts to a variety of environments, and does not pollute products and the environment; The internal antistatic agent is required to have good compatibility with the resin, do not affect the physical properties of the resin, have high antistatic performance and long-lasting, good heat resistance, can withstand the high-temperature processing of the resin, and has low toxicity. It is especially required to be used together with other resin additives without anti-interference. In the preparation of antistatic materials from polyolefin materials, many methods of adding antistatic agents have also made great progress in this regard. Dongxiujie [11] solved the incompatibility of plastic resin with antistatic agents and flame retardants by using ultra-small particle addition technology. Antistatic agents, bromide and other additives were added to HDPE and other plastics, and various antistatic and flame retardant plastic products were made by molding. All the raw materials used were made in China instead of imported, reducing the cost: the surface resistivity (P) of its antistatic and flame retardant material HDPE was 1 × About l08 Ω, and the afterburning time is less than l s. Ding Yunsheng [12] prepared polypropylene (PP) with antistatic properties by blending and compounding. The effects of the amount of antistatic agent, the mixing mode of antistatic agent and PP and the cooling mode on the surface resistance of antistatic PP were investigated; The antistatic mechanism of antistatic agent in polymer was discussed. The results showed that when the mass ratio of antistatic agent hkd2151 to hkd2520 was 1 ∶ 1 and the dosage was 1.5% of the mass of PP, the antistatic property of PP was better; Compared with high stirring mixing mode, cold roller mixing is helpful to improve the performance of antistatic PP; Quenching is better than gradual cooling. Composite antistatic agent is an important part of new varieties of plastic antistatic agents. Composite type is developed by using the principle of synergistic effect of each component. Each component is highly complementary, and its antistatic agent effect is much better than that of a single component [13]. For example, hydroxyethylamine is compounded with fatty acid polyol esters or fatty acid derivatives of alkanolamide, and it can obtain obvious antistatic effect when used in PE and PP. Add 0.2 parts of capric acid monoglyceride, 0.3 parts of crotonic acid and 0.1 parts of dodecyl diethanolamine to pe/pp copolymer 100

Copyright © 2011 JIN SHI