Our focus on developing low smoke zero halogen flame retardant cable material
Flame retardant wire and cable is usually divided into general flame retardant wire and cable, low smoke low halogen flame retardant wire and cable and low smoke zero halogen flame retardant wire and cable. At present, our country's low smoke zero halogen flame retardant wire and cable material mainly rely on import, the price is expensive, application by certain restrictions. With the rapid development of China's economic construction, to improve the safety performance requirements, the demand for low smoke zero halogen flame retardant wire and cable is more and more big, many domestic manufacturers are stepping up efforts to low smoke zero halogen flame retardant wire and cable material were developed. In 2002, the ministry of public security issued a mandatory standard GA306-2001 of the flame retardant and fireproof cables, plastic insulated flame-retardant and fire-resistant cable classification and requirements, and has carried on the classification to fireproof cables, and the smoke of fire-resistant cable and made specific provision smoke toxicity to further improve the flame retardant and fireproof cable standard system in our country, the promotion and application of flame retardant, high efficient and pollution-free flame retardant, fire-resistant cable plays a promoting role. Began in 2000, cable materials in short supply in our country, some products there are even out of stock. At present, there are nearly 5000 enterprises wire and cable production in our country. Because urban and rural power grid reformation, the development of the western region, the three Jia engineering and communications facilities large upgraded the huge demand for wire and cable products. So, from the point of a period of time, cable materials in our country has broad market prospects for development. In the early 80 s, overseas has developed a low smoke zero halogen flame retardant cable material. To the late 80 s, has developed the second generation of wire and cable with halogen free flame retardant plastic. Compared with the first generation product, the second generation of halogen free flame retardant plastic in addition to the flame retardant performance, smoke, toxicity, corrosion resistance, mechanical properties and electric properties improved, its high-speed extrusion performance is a major characteristic.
Japan issued each year more than 50 pieces of halogen-free flame retardant cable materials related patents. Most of these patent belongs to Hitachi wire co., LTD, Japan union carbide and the rattan company warehouse, sumitomo, Japan and other wire. Such patent tried to use different method, solve the problem of the center of the halogen-free flame retardant cable materials, which overcome the contradiction between flame retardant properties and other performance, comprehensive balance of various performance; Otherwise many patent is committed to developing new type of chelating agent, magnesium hydroxide is a kind of very important cooperation agent. Has a patent in many countries. Low smoke zero halogen flame retardant wire and cable compound is the future focus direction of the flame retardant wire and cable.
Flame retardant containing halogen flame retardant wire and cable products in China at present, this kind of wire and cable when burnt, release a large amount of smoke and corrosive halide, causing casualties and all sorts of equipment corrosion, the so-called "secondary disaster". To achieve low smoke, low toxicity and flame retardant, many manufacturers at home and abroad are committed to low smoke low halogen, low smoke zero halogen flame retardant materials development. This kind of material is burned less smoke, releasing toxic gas, reducing the harm of human body and equipment. In the developed countries for low smoke low halogen, low smoke zero halogen flame retardant wire and cable material an earlier study, technology is mature, now has entered the practical stage. For low smoke low halogen, in our country, especially in low smoke zero halogen flame retardant wire and cable materials research and development of late, at present our country for low smoke zero halogen flame retardant wire and cable material research is still in the early, some manufacturer producing low smoke zero halogen flame retardant wire and cable materials, but most of the problems with poor mechanical properties and processability.
1, the low level of technology
The technology level of China's wire and cable material has been and abroad. In the early 80 s, many manufacturers in the cable industry in our country successfully developed general flame retardant cable. According to statistics, 1987-1991, has developed more than 40 flame retardant cable, basically adopts the flame retardant PVC and neoprene, the flame retardant cable is only suitable for occasions with low requirements, and for some special occasions with higher flame retardant grade, requires the use of low smoke, zero halogen flame retardant cable, such as: underground utilities, high-rise building, ships, warships, etc., due to low technology in our country, resulted in the low production capacity, the vast majority rely on imported from abroad to meet demand, and by foreign technology monopoly, low smoke zero halogen flame retardant cable material price is very high, in 25000 yuan/ton - 25000 yuan/tons, paid a high price in China.
2, application field is limited
Low smoke zero halogen flame retardant cable materials because of its environmental protection conform to the requirements of society, is the development direction of cable materials in our country, but so far our country's low smoke zero halogen flame retardant cable materials application field is very limited, is mainly used in the subway in big cities, urban rail, ship, high building and plant and other fields, in Beijing, Shanghai, guangzhou, xi 'an, shandong and other developed provinces and cities, in many remote places rarely used, is far from universal.
3, broad prospects
As the "environmental protection cable" - halogen free flame retardant cable has a broad market prospect.
Our domestic wire and cable production accounts for about 20% of global production, according to the output calculation about 15% of the total output value of the world wire and cable, which is about 80 billion yuan (RMB), China has become the world's largest wire and cable market. With the development of the society, people on the environment problem more and more attention, many countries have developed all sorts of environmental policies, such as the eu ROHS directive: from July 1, 2006, in new on the market of electrical and electronic equipment, banning the use of lead, mercury, cadmium, hexavalent chromium, polybrominated diphenyl ethers (PBDE) and polybrominated biphenyl (PBB), and other harmful substances. The PBDE and more PBB used in flame retardant plastic class; Japan's top electronics company has formulated the corresponding requirements, since March 2006, all kinds of wire and cable used in electrical requirements no halide. Halogen-free flame retardant wire and cable, therefore, has become an important development direction of the industry. In our country, with the increase of degree of people's attention to the environment, halogen free flame retardant products used more and more widely, for example, in the home appliance industry, building materials, telecommunications, automobile and other industries has a great demand of halogen free flame retardant wire and cable. In terms of electrical appliances, our country has become the world's largest producer of electric appliances and the world's biggest exporter of electrical considering some countries to contain halogen products import restrictions, resulting in disguised form "technical barriers", so halogen-free flame retardant wire and cable in home appliance industry has great application prospect. Domestic existing rules for high-rise building must adopt halogen free flame retardant wire and cable. In addition, telecommunications infrastructure and auto thread with lines on the basis of the flame retardant is added in the numerous halide, above all, whether domestic or foreign, no halide is the developing direction of the flame retardant wire and cable, market prospects are very broad, has great market potential.
In our country, many enterprises are the low smoke zero halogen flame retardant cable materials technology research and development, promote the low smoke zero halogen flame retardant cable materials, the development of the market have also made some achievements.
Beijing university of chemical industry in 2004 developed a high-performance halogen-free flame retardant cable materials technology, for the first time in the domestic low filled with red LinXie effect using nanometer magnesium hydroxide flame retardant in the new method and two different surface treatment status of micron magnesium hydroxide with technology, make the material has high strength, high flame retardant, good liquidity, good heat resistance, excellent comprehensive performance, performance reached the international advanced level of similar products, breaking the monopoly imports passive situation of the domestic market.
Beijing university of chemical industry successful development of halogen-free flame retardant cable material in performance can be comparable with the imported product, but the price is lower than imported products, for cable manufacturers to save raw material costs 3000 ~ 5000 yuan/ton, have extremely strong market competitive advantage.
In recent years, with the development of flame retardant cable materials technology, a new type of flame retardant cable has been produced. In Europe and the United States, and other countries, environmental protection wires and cables has become the mainstream of all varieties of cable products, government or import blame environmental protection cable is strictly prohibited. Ordinary contains a large number of halogen flame retardant materials, at the time of combustion will produce a lot of smoke and poisonous corrosive halolide gases, and halogen-free flame retardant main choice in polyolefin, so low smoke zero halogen cable after will be the main trend of development, from the following aspects of low smoke zero halogen cable material extrusion were discussed.
1, the extrusion equipment
(1) wire and cable extrusion equipment are the main components of the screw, it is related to the application range of the extruder and the production efficiency, in order to adapt to the needs of different plastics processing, there are many kinds of screw type. Low smoke zero halogen flame retardant cable materials containing high filling of magnesium hydroxide and aluminum hydroxide, so for the selection of screw type screw and it is generally selected too high compression ratio, generally in 1:1 ~ 1:2. The comparison between five appropriate.
(2) in the process of extrusion and a low smoke zero halogen cable material extrusion, the important factors that extruder cooling device, because of the particularity of low smoke zero halogen material, in the process of extrusion, large heat generated by friction, which requires the extrusion equipment should have good cooling device, can control the process temperature. This is a problem which cannot be ignored, if the temperature is too high will lead to produce very big pores, the surface of the cable temperature is too low and can make the equipment of the machine current increase, easy to damage the equipment.
2, extrusion die
Because of the low smoke zero halogen cable material filler material is high, this leads to it under the molten state viscosity of the melt strength, stretching ratio and there are big differences with other cable material, so the mould have different selection, the choice of first is the way out of the mould. For low smoke zero halogen cable material extrusion, the insulation extrusion mold should choose extrusion type, and in the process of sheathed extrusion should choose half extrusion type, so as to fully guarantee the material tensile strength and elongation, and surface finish. Followed by the choice of die set, using extrusion mold, due to material viscosity is bigger, makes the nose a lot of pressure, when extrusion leave mould expansion, so the mould sleeve should be smaller than real size. Finally no ordinary on the mechanical properties of the low smoke zero halogen cable materials and low smoke low halogen material is superior, the draw ratio is small, only about 2.5 ~ 3.2, so in when choosing mould also should fully consider its tensile properties, which requires the die set equipped with not too much, otherwise the surface of the cable is not dense, and crowded package is loose.
At present our country the low smoke zero halogen flame retardant cable material technology, and foreign technology and very large gap to the Chinese government in such aspects as policy, fund input, research and development, to study the introduction of foreign advanced technology, to promote our country's low smoke zero halogen flame retardant cable materials technology rapid development.