Rubber with insoluble sulfur trends

Insoluble Sulfur is a common sulfur allotrope, which is hydrogen sulfide and sulfur dioxide by the reaction, and may be inclined to ordinary sulfur sulfur obtained by thermal polymerization. Its molecular structure of the sulfur is linear polymer with the characteristics of insoluble rubber, and are thus insoluble sulfur or sulfur polymerization. Insoluble Sulfur is currently mainly used in rubber industry. With the oblique side of sulfur, insoluble sulfur rubber vulcanization agent as its main features are:

1) insoluble sulfur in the rubber in a state of scattered and therefore do not rubber spray frost, a good sticky, at the same time ensure the quality of the appearance of light-colored products.

2) insoluble sulfur in the rubber compound spread uniformity, effectively inhibiting the aggregation of sulfur, is expected to reduce plastic storage process tend to scorch. 3) oblique to S S. The higher the stability of the ring, cracking keys for 268kJ/molE, higher than the insoluble sulfur bond energy, so the process has the tendency to scorch earlier.

As a result, even though the price of insoluble sulfur is a common side oblique sulfur 5 to 10 times, but not with its spray of cream and is widely used in tire rubber and other products (including tire), also applies to the high amount of sulfur Light-colored rubber products.

Insoluble Sulfur a history of the development

Dums sulfur in 1827 will melt in the water to be injected into a plastic sulfur. Berrthlot in 1857 through electrolysis sulfate solution has been the sulfur polymer. But these are difficult sulfur polymer to maintain its state polymerization, easy to restore the ramp side of sulfur. In 1906, and Smith will Holimes sulfur steam-soluble mass fraction of the 2 iodine in the water. 19l1 years Wiganal sulfur will melt in the cold at first non volatile nitrogen gas or a mixture of ice and ethanol, obtained by the polymerization of sulfur can be basically maintained the form of poly-sulfur, sulfur polymer research provides assurance. The 1930s, U.S. companies Stauffer has been prepared by low-grade insoluble sulfur patent (insoluble sulfur mass fraction of 50 ~ 60%), followed by the realization of industrial production. 50 era of the 20th century after the United States, Britain and France, since the 1960's the former Soviet Union, Japan and Eastern European countries, such as one after another of insoluble sulfur carried out research and development. As the insoluble sulfur in the production process there is a flammable, explosive, static electricity, erosion, toxic and other dangerous until the 1970s in the United States until the latter part of Stauffer's great success, the goods of Crystex insoluble mass fraction SULFUR reach 90, and gradually the production of oil-filled type of insoluble sulfur products. This product has been sold Dutch company AKZO. China in the 1970s began to study in 1978 on the crumbs Haiwa chemical production, products fail indicators. In 1984, of insoluble sulfur through research, the level of quality to be improved to achieve the industrial production. "July 5" during the radial tire In order to meet the requirements of domestic raw materials, Beijing, Shanghai Chemical Industry Corporation and Beijing Hai Rubber Industry Research and Design Institute in order to Crystex products as the goal, the development of high-grade insoluble sulfur products, and the formation of 6000t / a production Capacity. At the same time, and the Nanjing Chemical Industry Research Institute to develop a common professional standards insoluble sulfur. In the rapid development of high-grade products, insoluble sulfur IS-90 of insoluble sulfur mass fraction of more than 95, insoluble sulfur IS-60 to reach 63 or more and exports of France, Brazil and the United States and other countries.

2 domestic insoluble sulfur manufacturing technology and quality of the status quo

In recent years, with the rubber industry of insoluble sulfur performance and quality requirements, domestic sea Beijing to Shanghai-based chemical company, in the high-content, high stability, high dispersion, and other performance indicators, some progress has been made. In addition, the insoluble sulfur additives can be added to more fully restore the carbon black in the iron and suppress and eliminate the production process of nitrosamines, the protection of the environment plays a significant role.

2.1 insoluble sulfur manufacturing technology

Insoluble Sulfur of the manufacturing process of industrialization has been the main contact method, the gasification method, melting method.

2.1.1 contact with law

To hydrogen sulfide and sulfur dioxide as raw materials, through their respective acidic medium reactor contact reaction, the system can not insoluble sulfur. Reaction to the product of soluble and insoluble sulfur mixture of sulfur, the mixture by washing, drying, grinding, extraction processes to be insoluble sulfur.

2.1.2 gasification method

Sulfur will be heated to boiling point, so that the sulfur steam to over 500 ~ 700 ℃, relying on its high-speed pressure superheated steam injected into a stabilizing agent with the media, to be soluble and insoluble sulfur sulfur mixture of plastic. Curing until after the extraction of soluble carbon disulfide sulfur, to be immediately after drying insoluble sulfur products. To improve the process into a certain amount of hydrogen sulfide, so that the production process to reduce the viscosity of the raw materials, so as to improve the insoluble sulfur products stability. Information: gasification as the temperature increases, insoluble sulfur to increase the percentage, but high temperature corrosion of equipment increased the speed and power consumption increase.

2.1.3 melting method

In the 130 ~ 150 ℃ under the molten sulfur so, add a certain amount of stabilizer, and then the mixture to a temperature of 180 ~ 210 ℃. Stir in maintaining a certain amount of time, at this time, the maximum soluble sulfur into insoluble sulfur. Rapid cooling water, and water separation, in the air curing. After block-smashing, adding solvents, abrasive additives, filtering, to be the insoluble sulfur powder.

In addition, the Taiyuan University of Technology Institute of Chemical Technology SHI Kai et al, for insoluble sulfur manufacturing process of combustion, explosion, electricity, toxic, corrosive and other issues to come up with the success of insoluble sulfur production of low-temperature method, use a special solvent mixture in place of carbon disulfide-sulfur check insoluble . Now have the conditions for industrial production. At the same time, Nanchang University, Chongqing University, Sichuan Institute of natural gas, and so on more than 30 research institutes, institutions of higher learning in the development of chemical and insoluble sulfur manufacturing technology for a lot of work.

2.2 insoluble sulfur stability

Insoluble Sulfur is a measure of the stability of product quality advantages and disadvantages of one of the key indicators, which refers to a certain temperature after a certain period of time, the mass fraction of insoluble sulfur and heat before the mass fraction of insoluble sulfur ratio, the thermal stability of the Pros and cons of rubber processing components of the surface conditions and the performance of products have a greater impact.

When sulfur reached a certain temperature, the sulfur molecules into a ring with eight double-side of straight-chain free radicals. As the temperature rises, the end result of free radical chain polymerization, the growth of dual-side chain into a free radical. At this point by adding a stabilizer and two-terminal long chain reaction of free radicals, so that the side-chain free radicals to be closed, there will be a different molecular structure of long-chain molecules. As a result, the stabilizer choose to become insoluble sulfur in the process of producing the most critical links. It has been reported, halogen and its derivatives, organic acids, olefin, Lewis acid-base system can be insoluble sulfur as a stabilizer. In recent years, around the stabilizer in the development, for a lot of work, such as the red-use of ferric chloride solution of nitric acid, water, Zhao Bin, after the development of isobutyl alcohol test, so that the stability of insoluble sulfur increases. Different stabilizer preparation of insoluble sulfur vulcanization of rubber on the impact remains to be proved.

In addition, the trial proved that the oil-filled preparation of insoluble sulfur filled oil on the insoluble sulfur thermal stability is also larger.

2.3 insoluble sulfur oil-filled

The general is insoluble sulfur powder, the size of about 150μm and easy to dust, transportation inconvenience and at the same time using the process would not be easy to evenly spread over the rubber, environmental pollution to a certain extent. Therefore, at this stage generally used to deal with oil-filled, in order to prevent the formation of dust, makes insoluble sulfur in the mixture of oil and more scattered in the rubber. Is to be combined with stabilizer of insoluble sulfur with a fraction of petroleum products by a certain percentage of mixing evenly, not insoluble sulfur particles on the surface was completely coated by oil. In general, the aromatic oil refining and oil cycloalkanes good, splitting the functions and histocompatibility; but aromatic oils and naphthenic oil and refined through the pickling methods, and other improvements, will cause the cost of oil increased, thus raising the necessary and sufficient Insoluble Sulfur oil prices. At present, the insoluble sulfur varieties of oil-filled for the most general of the aromatic oil, oil products which contained impurities, the basic material of insoluble sulfur have a greater impact on the stability. Information: adjusting the composition and oil-filled add the appropriate control agents, so that the aromatic impurities to achieve a more stable structure, so that the basic material and to achieve, so that oil-filled stability of insoluble sulfur by about 39 to 70% to 88%, and oil-filled dispersion reached a similar foreign products.

In recent years, Beijing, Shanghai, Beijing and the sea Rubber Industry Research and Design Institute co-operation has been able to mass production of high content of insoluble sulfur IS95, high temperature stability of insoluble sulfur IS-HS, high dispersion of insoluble sulfur IS-HS-AS such as the "three high" products , Technical indicators Crystex basically reached the level of similar products, and to more fully restore the carbon black in the iron and suppress and eliminate the production of rubber in the process of nitrosamines. Insoluble Sulfur of additives at room temperature and 100C with the rubber production process of the formation of relatively stable NO nitroso compounds, and inhibit NO Zhong promoter of the amines, undermining the formation of nitrosamines, which is to improve the environment Great.

2.4 Problems and Countermeasures

Insoluble Sulfur in China's production technology, product quality Crystex basically achieve the same level of product quality. At the same time, nearly more than 20 provinces and cities have more than 30 research institutes, institutions of higher learning and research and development in the chemical insoluble sulfur, and there are dozens of different sets of production equipment. But so far was a lone fighter for each array, yet the formation of scale. Even in Beijing, Shanghai Chemical Industry sea, the production of small scale, part of the unit is relatively backward equipment, the cost is relatively high in the international market is not competitive. The main reason is inadequate feasibility studies, one-sided account of the region's raw material resources, industrial layout ignored, the source of technology, technical reliability, transport and economic factors; followed by the manufacturing technology is not enough to master, the lack of manufacturing Technology involved in the chemical process, explosion-proof technology, anti-technology, high temperature technology, raw materials selection, pre-processing of raw materials and control systems, such as in-depth understanding and mastering This is not the last 20 years the main reason for economies of scale. This should be a high degree of attention, on the one hand, government departments must raise the production of insoluble sulfur coordination, the formulation of relevant policies to induce or appropriate to take forceful means to carry out administrative intervention, it is necessary to have the conditions and after verification, inspection, Policy to give preferential treatment to be given to tilt the financial resources, to technical support. On the other hand, the industry should be done in accordance with the current quality of insoluble sulfur status quo, in recent years, the Organization of insoluble sulfur development of effective institutions, scientific research institutes to conduct research group, do each other as soon as possible the formation of insoluble sulfur integrity of our production technology. At the same time, enterprises must seize this opportunity to strengthen research cooperation and to strengthen the high-tech research and development and reserves, which is a positive solution to the problem.

3 insoluble sulfur direction of development and market forecast

3.1 insoluble sulfur direction of development

At present, the world's highest levels of insoluble sulfur by the Flexsys chemical company, its products, called Crystex (Flexsys is AKZO Netherlands and the United States Monsanto Chemical Company, a subsidiary of Commonwealth). The main technical indicators are as follows: insoluble sulfur mass fraction (of total sulfur element) ≥ 90%; size distribution (150μm) ≥ 99.5%; the stability of high temperature (105 ℃ in the conditions, 15 min its insoluble sulfur content): Crystex HS OT20 insoluble sulfur mass fraction> 75%; Crystex HS CT33 insoluble sulfur mass fraction> 80% from the standard indicators can be seen insoluble sulfur content is high, the stability of high temperature and high-dispersion characteristic. In recent years, with the continuous development of rubber products, in particular the development of the radial tire, the insoluble sulfur performance and quality indicators continue to put forward new demands, that is, high-content, high temperature stability, high dispersion, France Micheline, Japan's Bridgestone, Goodyear Tire companies, such as the United States put forward the insoluble sulfur mass fraction ≥ 95%, insoluble sulfur size ≤ 63%, but also to carry out complex high-performance distributed. At the same time, major tire companies such as the introduction of the radial tire production line, but also made use of the "three high" performance of insoluble sulfur. According to the U.S. company罗纳普拉克of the third generation of rubber products used Crystex analysis, the product is high-quality raw materials for the insoluble sulfur, so as to resume the high dispersion of polymer resin and help dispersant, mixed into granulator. After the actual use of its easy-to-rubber dispersed, homogeneous product performance, and weighing convenience, non-polluting, in the market is relatively competitive. Flexsys agents in the domestic distribution agent. It can be that insoluble sulfur content in the high, high stability and high dispersion will be the direction of its development. This is the modern rubber processing technology of high-temperature requirements of the insoluble sulfur is also a fundamental way to expand their markets.

3.2 Market Forecast

Despite the insoluble sulfur is a narrow use of the product only for the rubber industry, to limit the use of the market, but in accordance with existing domestic more than 30 articles, as well as radial tire production line of radial tire production this year insoluble sulfur market Demand is expected to reach 10000t. With the radial tire market share gradually expanded in 2005 to domestic demand insoluble sulfur will reach more than 15 000t. At present, insoluble sulfur production capacity: in 2001, according to incomplete statistics, the actual production (China Rubber Association unit) was only 8460t, which can be seen insoluble sulfur is still considerable potential for development. From the international market, currently only a small number of foreign countries, such as the United States, Russia, Japan, Germany, France, India and Eastern Europe can produce insoluble sulfur, insoluble sulfur demand in the market for more than 160,000 t, but the market was almost Flexsys Company An exclusive monopoly. To this end the world's major tire companies and trading companies in different countries hope that the insoluble sulfur to compete in order to break the monopoly. Beijing, China's production of sea-insoluble sulfur have been exported France, the United States. In 1999 there 500t insoluble sulfur German exports, Southeast Asia, the United States, Japan and other countries. If the economies of scale, and the product of the "three high" in areas such as a further breakthrough in the international market will be very competitive. Insoluble Sulfur market demand will surge in demand for its annual 15 to 20% of the speed increase, the market prospects.

4 Conclusion

Insoluble Sulfur rubber as a new type of cross-linking agent used in China is still at the stage of development. With the rubber industry, large market potential, a good prospect. To take full advantage of scientific research institutes, institutions of higher scientific and technological achievements, from the layout of the product, sources of raw materials, technical level to fully consider upgrading insoluble sulfur "three high" on a breakthrough, as soon as possible economies of scale.