1. Overview
Polyethylene is the most important downstream products of ethylene, polyethylene (PE) accounted for 70% of the world's consumption of polyolefins, accounted for 44% of the total thermoplastic general-purpose plastics consumption, consumption of the world's ethylene production of 52%. Polyethylene is basically categorized into three main types, namely high-pressure low-density polyethylene (LDPE), high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE). Film is its main processed product, followed by sheets and coatings, hollow containers such as bottles, cans, drums and other various injection and blow molded products, pipes and insulation and sheathing for wires and cables. Mainly used in packaging, agriculture and transportation sectors. Compared with other countries in the world, China is used for agricultural film LDPE and LLDPE amount is more. China is the world's largest production of agricultural film, which is determined by the characteristics of China's large agricultural country.
2. Production capacity and output
By the end of 1998, China has built 26 sets of polyethylene devices, with a total capacity of 2.51 million tons.
3. Production Methods in Brief
HP-LDPE is produced by two kinds of high-pressure liquid-phase process, namely, kettle method and tube method. The kettle process produces polymers with a narrow molecular weight distribution and more branched chains, while the tube process produces products with a wider molecular weight distribution and fewer branched chains.
The kettle and tube process steps are similar except for the polymerization reactor. The maximum single-line reactor capacity of the tubular process is 200,000 tons/year (e.g., Exxon's plant in Belgium and DSM's plant in the Netherlands), while the maximum single-line reactor capacity of the kettle process is 180,000 tons/year (with the possibility of reaching 200,000 tons/year), which is the QGPC plant in Qatar using Orchem (CdF) technology.
The kettle process and tube process have their own merits, generally speaking, large-scale device tends to use the tube method; production of specialized grades of the device is more inclined to use the kettle method. 1998 November put into operation in Qilu Petrochemical Company's LDPE plant, the use of the Netherlands DSM high-pressure tube method process, is the most similar devices in China's current product grades, the largest production capacity of a single line of the largest device. Yanshan Petrochemical Company will also build a 200,000 tons/year LDPE plant, using Exxon technology, the contract has been signed.
Linear polyethylene (HDPE/LLDPE) is produced by low-pressure liquid-phase method and gas-phase method. The two current liquid phase methods in the world, the slurry method and the solution method, are still dominant in terms of total production. Important solution-phase processes are the medium-pressure process of DuPont (now Novacor) in Canada, the low-pressure cooled process of Dow and the Dutch Mining Company (DSM) process. Each of these plants can alternately produce HDPE and LLDPE (industrially known as convertible plants, domestically known as full density polyethylene). The two most widely used slurry processes are the ring tube reactor process with light diluents (Phillips and Solvay) and the stirred tank process with heavy diluents (Hoechst, Nissan, Mitsui). The primary product of the slurry process is HDPE, but some MDPE can be produced as a secondary product.
UCC and BP are the major holders of line-type polyethylene vapor phase process technology. Gas phase units are generally convertible units that can produce LLDPE and HDPE alternately, subject to certain limitations in the patent agreements. Units licensed to produce both products are also typically required to prioritize the production of one product for an extended period of time. Even for convertible units, frequent interchanges between HDPE and LLDPE products are uneconomical and are not practiced.
The world's peaceful capacity for polyethylene in 1997 was about 50.7 million tons per year, with North America and Western Europe accounting for more than half of the world's total capacity. Asian countries (including Japan) accounted for about 1/4 of the world's total capacity. as far as the process is concerned, high-pressure polyethylene accounted for about 38% of the total, and the tube method and kettle method accounted for almost half each. The slurry process accounts for about half of the 62% share held by bus type polyethylene. In China, the proportions of kettle method, tube method, slurry method, vapor phase method and solution method in the total polyethylene production capacity in 1998 were 9%, 18%, 26%, 43% and 3.2% respectively. Compared with the world average proportion of capacity of various process methods (19%, 19%, 30%, 24% and 8), the gas-phase method is high, the tube method is similar, and all other methods are low.
In recent years, China's polyethylene industry in catalyst development, localization of process equipment and new product development has also achieved promising results.
Significant progress in catalyst localization 30 tons / year localized HDPE catalyst production unit has been built in Yanshan Petrochemical Company, the production of catalysts have been used in large-scale industrialized devices. At present, the domestic catalyst in the slurry method of HDPE device applied to the recapitulation rate has exceeded 80%.
China's metallocene catalyst research has made promising progress, by mid-1996, *** developed five mold test or patented technology, has obtained five Chinese patent application number, Beijing Petrochemical Science and Technology Research Institute, Lanzhou Chemical Industry Company and the Shanghai Research Institute of Chemical Technology has been in the gas phase fluidized bed mold test device with bimodal molecular weight distribution of the mau - LLDPE, Shiyi Academy of Sciences. The metallocene catalysts that can produce high-density, low-density, ultra-low-density and long-chain branched polyethylene resins have also been synthesized, and the loaded bridged zirconium metallocene catalysts developed by the Academy of Science and Technology of China have been validated in different scales of medium-sized tests. The metallocene catalyst APE-1S developed by the institute has successfully passed the pilot test in Liaohua, and has completed the pilot evaluation test in the continuous reactor of ring tube slurry method in cooperation with Phillips Company of the U.S.A. The test shows that the catalyst has higher activity and better catalytic ability for 1-hexene*** polymerization, and the polymerized products have better particle size distribution and higher stack density. In March 1999, the catalyst passed the appraisal organized by China Petroleum and Chemical Corporation and China National Petroleum Corporation.
The process development has achieved fruitful results, Shanghai Research Institute of Pharmaceutical Industry, Yangzi Petrochemical Company Design Institute and Yanshan Petrochemical Company and other units developed the slurry method of high-density polyethylene process. The 140,000 tons/year HDPE plant of Yanshan Petrochemical Company was designed and constructed by our country, and it took only 27 months and 25 days from June 1, 1992, when the program was determined, to September 26, 1994, when the plant was completed and put into operation, and the foreign exchange was saved 47.43 million Yuan compared with the introduction of the technology and construction of the equipments. After the process and in Lanzhou Chemical Industry Company built 70,000 tons / year production line.
Yangzi Petrochemical Company completed in the same kind of device with advanced level of "200,000 tons per year slurry method of high-density low-pressure polyethylene complete sets of technology and process packages", in 1997 through the China Petrochemical Corporation appraisal. The use of this technology can significantly reduce the construction cost of new polyethylene plants, and can effectively guide the expansion and transformation of existing plants.
Shanghai Pharmaceutical Industry Design Institute and Yanshan Petrochemical Company jointly developed a slurry method and horizontal gas-phase kettle tandem full-density polyethylene production of new processes, has applied for a patent in China, and is ready to Yanshan's industrialized units on the implementation.
The development of new products has made certain achievements. Qilu Petrochemical Company production of high-strength film, pipe and large hollow containers has become the company's fist product, HDPE wrapped pipe special material following the national key project Shaanxi - Beijing natural gas gathering and transmission projects in the successful application, and recently in the international bidding to beat a number of well-known foreign companies, to achieve the Egyptian pipeline anticorrosive plant exports, breaking the Europe and the United States completely control the situation of the Middle East synthetic resin special material. The situation is broken. Yanshan Petrochemical Company trial production of high molecular weight, wide molecular weight distribution, ESCR performance of the pipe material 6000 M. Beijing Research Institute of Chemical Technology successfully developed for automotive fuel tanks HDPE material, the Institute simulated two kettle tandem method of two kettle polymerization of ethylene in 2-liter polymerization kettle, the preparation of molecular weight distribution of high molecular weight bimodal molecular weight butene *** polymerization of HDPE resins, performance indexes with the foreign single layer of the base resin for automotive fuel tanks. The performance indexes are comparable with the performance of the base resin of the special material for automobile fuel tanks in foreign countries.
4. Demand
In 1998, China's polyethylene production of 2.3 million tons, of which 740,000 tons of HDPE, LDPE 591,000 tons, LLDPE (including full-density polyethylene devices in the production of HDPE) 971,000 tons. 1998 China's net imports of polyethylene 2.42 million tons, the apparent consumption of 4.72 million tons. In 1998, China's polyethylene production capacity was about 4.5% of the world's production capacity (55.23 million tons), and the apparent consumption was 10.8% of the world's consumption (43.7 million tons). Because a considerable part of the imported polyethylene in China is processed from incoming materials, but half of the resin processed from incoming materials often stays in the country. Calculation of demand, according to 60% of imported resin to feed processing imports, and to feed processing of polyethylene in the half of the stay in the country, that is, according to the imports of 70% of the amount is to meet domestic demand.
5. Growth rate
1983-1998 China's average annual growth rate of polyethylene consumption of 15.2%, for the GDP growth rate (10.3%) 1.5 times. 1993-1997 China's polyethylene devices, the average operating rate of 90.5%.
6. Application Distribution
The largest amount of LDPE is film and sheet, followed by extrusion coating, injection molding, wire and cable. These four applications total*** 90% of LDPE applications.
Film is the largest market for LDPE, with packaging and non-packaging applications accounting for roughly 50% each. Extrusion coating is the world's second largest market for LDPE, is the fast-growing application of LDPE, mainly due to the development of packaging technology and packaging styles continue to renovate.
Film and sheet applications account for 75% of world LLDPE consumption. Injection molding and wire and cable are the second and third largest applications of LLDPE, but only accounted for 7% to 15% of the total LLDPE consumption. Stretch-wrap film is the world's fastest-growing market for LLDPE in packaging, and is replacing strapping tape, corrugated board, wrapping paper and shrink wrap.
Packaging accounted for 75% of the amount of HDPE resin, construction accounted for 10% to 15%, while the remaining 10% to 15% for a variety of other consumer and industrial supplies. The United States and Western Europe blow molding and injection molding is the most important application areas, accounting for about 60% of the total consumption of ~ 50%, but in Japan and other countries in Asia, HDPE in these sectors of consumption is only 1 / 3 of the total consumption, according to the proportion of consumption, the proportion of Asian countries, the proportion of the film used in the United States and Western Europe is 2 times.
In the U.S. market, for example, the largest sector of HDPE consumption is all kinds of bottles, barrels, cans and bags, followed by sheet, pipe, boxes, trays and wires, cables, etc., but is expected to grow at the highest rate of application is the automotive fuel tanks, barrels and tanks, followed by liner boards, water supply and irrigation water pipe and geotechnical film.
Film accounts for almost 60% of China's polyethylene consumption (see table), of which agricultural film accounts for 20.4%. in 1998, China consumed more than 700,000 tons of polyethylene resin for agricultural film. China is the world's highest production of agricultural film, which is determined by the characteristics of China's large agricultural country. Other applications of polyethylene include pipes, sheets, hollow containers, monofilaments, woven products, injection molded parts, wires and cables. Domestic consumption of agricultural pipes, followed by drinking water pipes and gas pipes; hollow containers are mainly used for beverages, cosmetics, edible oils and pharmaceutical packaging. 1997 more than 100 liters of containers with resin consumption of about 60,000 tons; monofilament and woven products are mainly used for ropes, fishing nets, and colorful fabrics; cable materials are mainly used for insulation, cross-linked cable materials and sheathing materials; injection molded plastics are mainly used for the production of crates, plastic trays, plastic bottles and caps. plastic trays, plastic bottle caps and other products; others include polyethylene coating and chlorinated polyethylene.
7. Development prospects
Over the years, China's production of polyethylene has not been able to meet market demand, imports accounted for about half of the apparent demand. 1983-1997 China's average apparent demand for polyethylene to meet the rate of 46%, the average rate of 54%. If all of China's large and medium-sized ethylene can complete the transformation in 2002, it is expected that the capacity of polyethylene can be up to 3.7 million tons, with an output of 3.3 million tons based on the 90% start-up rate. According to the historical changes in demand, according to the development forecast of China's national economy, it is predicted that China's polyethylene demand in 2002 will be 5.86 million tons (apparent demand of 7 million tons), in 2005 it will be 7.9 (9.5) million tons, and in 2010 it will be 12.2 (14.8) million tons. The fulfillment rate and apparent fulfillment rate of polyethylene in China in 2002 are projected to be 56% and 47%, respectively. It is comparable to the average level of 1983-1997. Polyethylene has considerable market potential in China and is a very promising petrochemical product.
(B) polypropylene
1. Overview
Polypropylene is closely related to our daily life of the general purpose of the resin, is the most important downstream products of propylene, the world's propylene, 50% of China's propylene, propylene, 65% of the system are used to make polypropylene. Polypropylene is the world's fastest-growing general-purpose thermoplastic resins, the total amount of only after polyethylene and PVC. 1998 world polypropylene production capacity of 29.25 million tons in 1997, the world's total polypropylene production of about 23.9 million tons, the output value of about 21 billion U.S. dollars. World production has grown at an average annual rate of about 9% since 1991, second only to LLDPE among general-purpose resins.
Like other general-purpose resins, the Asian financial crisis has had a significant impact on demand for polypropylene, which has continued to grow at a relatively strong rate compared with other resins, even at the lowered forecast level. New forecasts indicate that world demand for polypropylene will grow at an average annual rate of 7.1% from 1997 to 2002, compared with 5.2% for polyethylene, 5.0% for PVC and 4.1% for polystyrene. The reasons for the rapid growth in demand for polypropylene can be simply summarized as follows, namely, cheap, light, good processability and wide range of uses, catalysts and the development of new processes to further promote the expansion of the field of application, such as automotive and food packaging and other new uses of the development of new applications to further promote the growth of demand, in the past, there is not so much polypropylene used in the automotive industry, and in the past, polypropylene is also seldom used in the blow molding and thermoforming process. It has been said that "whenever there is a product in which the material is replaced by plastic, there is potential for the use of polypropylene in that product".
2. Brief description of the production process - gas-phase and propriety processes in the gradual replacement of the slurry process
According to the reaction medium and reactor configuration, the polymerization process can be broadly divided into three basic types:
(1) propriety process, the polymerization of the liquid propylene in the process. The reactor can be a liquid kettle reactor, as in the Exxon, Mitsui (now Magnum Polymers), and Sumitomo processes, or a ring tube reactor, as in the Montell , Hoechst (now part of Targor), Phillips, and Solvay processes.
(2) The slurry process, in which propylene is dissolved in a hydrocarbon diluent such as butane, pentane, hexane, heptane, or nonane, and the reactor can be a continuously stirred tank reactor such as Amoco, Montell, Hoechst (now Tagor), Mitsui (now Magnum Polymers); an intermittently stirred tank reactor (e.g., Mitsui), an annular tube reactor (e.g., the Solvay) and reactions in boiling butane (the process was used by Huntsman at Woodbury, a unit owned by Shell until 1987).
(3) The gas-phase process, in which propylene is directly polymerized to produce a solid polymer, uses reactors such as fluidized beds (e.g., UCC and Sumitomo); horizontally stirred beds (e.g., Amoco/Chiso) and vertically stirred beds (e.g., BASF, now Targor).
Technically speaking, propriety polymerization is also a type of slurry polymerization, but the industry uses the term "propriety" for any process that uses propylene as a diluent, and calls it slurry polymerization for any process that uses a non-propylene diluent.
Currently, about 55% of the world's plant capacity is propriety, 25% is gas-phase, and slurry accounts for the rest. Since 1990, the number of slurry production units in the world has been declining, giving way to propriety and gas phase technologies. This is particularly evident in North America, Western Europe and Japan. This trend is expected to continue as the world's new and expanding capacity is largely utilizing gas phase and intrinsic methods.
According to the November 1998 CW Polypropylene Issue, the capacity of various polypropylene technologies and their share of total capacity are: 11 million tons of Montell's Spherilene (37% of the world's total); 5 million tons (17%) of UCC's SHAC process; 3.8 million tons (13%) of Targor Novolene; and 3.8 million tons (13%) of Sansho's Novolene process. million tons (13%); Mitsui Hypol 2 million tons (7%); Amoco 2 million tons (7%); Shell's early technology 800,000 tons (3%); El Paso 1 million tons (3%); Sumitomo 350,000 tons (1%). The remaining 12% includes units built with our technology.Borealis is building a new 200,000-ton polypropylene unit with its Borstar technology.
By the end of 1998, China's continuous polypropylene production capacity of about 1.8 million tons, of which 80% of the body method, gas-phase method accounted for 11%, slurry method accounted for 9%, in addition to a total capacity of about 700,000 tons of intermittent body method device, the device capacity ranging from 2,000 tons to 10,000 tons.
China's polypropylene process technology in the past two years there has been significant progress, the most important achievement is the development of propylene polymerization of high-efficiency catalysts and polypropylene production technology, in addition to the development of new products has also made significant achievements.
The N-type high-efficiency propylene polymerization catalyst successfully developed by Beijing Research Institute of Chemical Industry has been patented in China, the United States, Germany, Britain, France, Italy, the Netherlands and other countries. The catalyst has realized a long period of stable operation in large industrial units, producing a variety of grades of large tonnage of qualified products. Compared with the use of domestic catalysts and imported catalysts, a 70,000 tons/year unit can save nearly 8.3 million yuan per year. The U.S. Phillips Company, which cooperates with the institute, has built a 60-ton/year N catalyst production unit in Houston, U.S.A., and the products are sold to countries all over the world.
The successful DQ-1 spherical high-efficiency catalyst developed by Beijing Research Institute of Chemical Industry has passed the pilot test, and three stages of industrial test of homopolymerization, random **** polymerization and block **** polymerization have been carried out on 70,000 tons/year industrialized device, producing 7 grades of batch-qualified products, and the output has exceeded 10,000 tons. The catalyst has passed the appraisal organized by the Petrochemical Group Corporation, and the production unit has been completed and put into operation.
The CS-I catalyst and CS-2 catalyst developed by the Institute of Chemistry of the Chinese Academy of Sciences have also been used in a number of sets of polypropylene industrialization units in China and exported to foreign countries.
At present, the localization coverage of polypropylene catalysts in China has exceeded 2/3. Dalian Petrochemical Company Organic Plant, Yanhua Chemical Company Chemical Plant No.2, Lanzhou Refining and Chemical General Factory, and Qian Guo Refinery have built a set of 40,000t/a polypropylene plant using localized kettle-type propriety technology, which has been successfully put into production.
China has developed a polypropylene process using liquid-phase ring tube reactor with N-type high-efficiency catalyst. Changling, Wuhan, Jiujiang, Fujian, Jinan, Dalian, Jingmen 70,000 t/a polypropylene plant and Daqing 100,000 t/a polypropylene plant have been successfully put into operation, the performance indicators of the device have reached the level of similar devices introduced in the 1990s in China.
With the domestic construction of polypropylene ring tube reaction device equipment localization rate of 80.4%, the introduction of 70,000 tons / year of polypropylene plant total investment of about 9-10 billion yuan, while the same size of the localized device's total investment of less than 500 million yuan.
In terms of new product development, Yanshan Petrochemical Company has developed a polypropylene washing machine drum special material has been recognized by the quality of a number of domestic washing machine manufacturers; Shanghai Petrochemical Company has developed a series of special materials for polypropylene cast film, special materials for washing machines, and special materials for paintable automotive bumpers; Maoming Petrochemical Company's production of polypropylene special materials to replace the imported products, access to the Guangdong Midea Group Home Appliances Co. Ltd.; in cooperation with the Beijing Research Institute of Chemical Technology, Xiali automobile plastics used in most of the Sinopec Group Company's products, and is now continuing to research and develop automotive special materials for application in other models.
3. Domestic demand and growth rate in recent years
In 1998, China's polypropylene production of 2.07 million tons, net imports of 1.52 million tons, an apparent demand of 3.59 million tons. 1998 imports of resin in about 71% of the coming, processing and bonded warehouses and other non-general trade imports, but from this channel imports of resin may not be able to transform all the products re-exported, about half of about stranded at home. About half of it stays in the country. Estimated domestic demand for polypropylene is about 3 million tons. 1983-1998 15 years of production, net imports, apparent demand and demand for the average annual growth rate of 22.2%, 21.7%, 22.2% and 21.3%. 1993-1998 China's domestic demand for polypropylene growth rate of about 2.3% of the growth rate of the same period of the GDP ( 10.3%), the growth rate of the gross domestic product (GDP). 10.3%) of 2.1 times, more than the average growth rate of synthetic resins (16.7% and 1.6 times).
4. Domestic Prices
In January 2000, the price of polypropylene in China's Yuyao market for generic grades (drawing grade) was about 6,100 yuan per ton. Historically, the price of polypropylene and other general-purpose resin prices, ups and downs. 1995 by the world's various emergencies, polypropylene supply constraints, prices rose, artificial copying exacerbated the situation. 1995 2 quarter and 3 quarter of the price of general-purpose grades rose to more than 10,000 yuan / ton. 1997 4 quarter by the Asian financial crisis, the price dropped sharply, the first half of 1999 this decline is still the situation of the first half of the world's first half of the year. In the first half of 1999, this declining situation still could not be reversed, the price of generic grades fell to about 4,800 yuan. Since then there is a slow recovery, but the current price level is at most equivalent to the level of the fourth quarter of 1997, far from reaching the historical high prices. 5. Applications
The way polypropylene is consumed is influenced by the industrial structure of each region and varies from region to region. Generally speaking, injection molding applications account for a major share of consumption in industrialized countries, especially in those countries and regions with well-developed automotive industries. Agricultural countries in the early stages of industrialization, the proportion of fibers is greater, mainly used as woven bags, tarpaulins and so on. In industrialized countries, consumer durables such as automobiles, appliances and carpets account for about 50% of polypropylene end-use. Consumption in these markets is strongly influenced by the cyclical nature of economic development and consumption levels. Depending on the specific requirements of each application, polypropylene also competes with other thermoplastics, namely: (1) ABS in areas such as transportation and appliances; (2) nylon in transportation, carpet veils and nonwovens; (3) polyethylene in housewares, consumer products, rigid packaging, film and wire and cable; (4) polystyrene in rigid packaging and household appliances; (5) polystyrene in film, rigid packaging and carpet; and (6) polystyrene in automotive and consumer products. ) PET used in films, rigid packaging and carpet veils; (6) PVC used in films and medical supplies. polypropylene has a wide range of applications and many fields, and there is hardly any one application that can exceed 25% of the total market share of polypropylene.
China's production of polypropylene, used in woven bags of flat silk material accounted for about 50% of China's polypropylene production. From our country in 1997 a variety of polypropylene products, the supply and demand structure, flat silk material to meet the basic needs (domestic products to meet the rate of 87%), but the film material to meet the rate of only 30% of the domestic; injection molding to meet the rate of less than 10% of the domestic. Domestic production of injection molded plastic is mostly homopolymer (U.S. injection molded plastic **** polymer and homopolymer ratio of roughly 2:1), can only be used for daily necessities and other products that do not require high performance. From the domestic and imported materials listed in Table 5, the proportion of specialized materials, imported materials, the proportion of specialized materials is significantly higher than that of domestic materials. From the performance of imported grades, a considerable number of imported grades of polypropylene is MI high thin-walled injection molding grades and fibers, non-woven grades.
Compared with the application of the world's developed countries, China's injection molding (especially automotive) and fiber (especially non-woven) with polypropylene should also have a large potential market space.
6. Development prospects
According to China's polypropylene demand growth in the historical law and the development trend of China's national economy, we expect the future growth rate of polypropylene demand will still be higher than the growth rate of the national economy, predicted that China's apparent polypropylene demand in 2002 for 5.25 million tons in 2005 for 7.3 million tons in 2010 for 11.8 million tons (see table). If China's large and medium-sized ethylene in 2002 can be transformed to complete the forecast that China's polypropylene production capacity of up to 3.48 million tons, according to the start rate of 90%, the output of 3.13 million tons, when the apparent rate of satisfaction can reach 60%, there are still 40% of the polypropylene * imports to meet.