The Styrene Market

Styrene is at the centre of an important industry, with a value of some 66 billion euros. The styrene production capacity is ca. 20 Mt/a worldwide. Most is obtained by ethylbenzene dehydrogenation and all the production is used for the synthesis of polymers (polystyrene, styrene-acrylonitrile, styrene-butadiene) used as plastics and rubbers in the manufacture of household products packaging, tubes, tires, and endless other applications (see also Chapter 7). 

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J. A. Valentine and co-workers. Increase Competitiveness in the Styrene Market, 1992, Sud-Chemie International Styrene Symposium, Ohita, Japan, Nov. 9,1992. 

There are several alternatives to the polluting chlorohydrin route. One is the styrene monomer propene oxide (SMPO) process, used by Shell and Lyondell (Figure 1.6a) [14]. It is less polluting, but couples the epoxide production to that of styrene, a huge-volume product. Thus, this route depends heavily on the styrene market price. Another alternative, the ARCO/Oxirane process, uses a molybdenum... 

Styrene is manufactured from ethylbenzene. Ethylbenzene [100-41-4] is produced by alkylation of benzene with ethylene, except for a very small fraction that is recovered from mixed Cg aromatics by superfractionation. Ethylbenzene and styrene units are almost always installed together with matching capacities because nearly all of the ethylbenzene produced commercially is converted to styrene. Alkylation is exothermic and dehydrogenation is endothermic. In a typical ethylbenzene—styrene complex, energy economy is realized by advantageously integrating the energy flows of the two units. A plant intended to produce ethylbenzene exclusively or mostly for the merchant market is also not considered viable because the merchant market is small and sporadic. 

U.S. petroleum benzene prices since 1974 are Hsted in Table 6 (64). Until 1978, benzene prices were relatively stable and through 1985 they increased considerably, peaking in 1981 because of the increased demand for aromatics in the gasoline pool. At that time, there was also a large surplus of low priced imported benzene and a softening of the ethylbenzene—styrene market. The decline of cmde oil prices in 1986 caused a dramatic drop in domestic benzene prices. In 1987, U.S. benzene production increased 13.9% over 1986, and this rise was largely ascribed to a favorable export market for benzene derivatives... 

Global consumption of thermoplastic mbbers of all types is estimated at about 600,000 t/yr (51). Of this, 42% was estimated to be consumed in the United States, 39% in Western Europe, and 19% in Japan. At present, the woddwide market is estimated to be divided as follows styrenic block copolymers, 48% hard polymer/elastomer combinations, 26% thermoplastic polyurethanes, 12% thermoplastic polyesters, 4% and others, 9%. The three largest end uses were transportation, 23% footwear, 18% and adhesives, coatings, etc, 16%. The ranges of the hardness values, prices, and specific gravities of commercially available materials are given in Table 4. 

Photodegradation may involve use of inherently photo-unstable polymers or the use of photodegradant additives. An example of the former are ethylene-carbon monoxide polymers in which absorption of light by the ketone group leads to chain scission. The polymer becomes brittle and forms a powder. Such materials are marketed by Dow and by Du Pont. Other examples are the copolymers of divinyl ketone with ethylene, propylene or styrene marketed by Eco Atlantic. 

The reverse occurs in the production of foams and consumer items. These plants are usually constructed close to the prospective markets. Insulating materials are often so light that the cost of shipping per ton is very high. Only a small amount of mass can be loaded in a boxcar or truck. The density of polystyrene is 2.4 lb/ft3 (38.5kg/m3). It is made from styrene, which has a density of 56.3 lb/ft3 (902 kg/m3). The foam product occupies 23 times as much space as the styrene, and the polystyrene would cost between 10 and 20 times as much to ship. 

One feature of many commodity chemicals is that they are essentially intermediates used in the production of a wide range of consumer products. It was once suggested that the per capita rate of production of sulphuric acid was a measure of a country s prosperity, although the consumer demand for sulphuric acid itself is almost zero. Similarly styrene, most of which is converted into polystyrene, is hardly a saleable product in the retail market. The exception, on the other hand, is the market for materials that are finally utilised as fuels many of which are distributed to the final consumer following various degrees of polishing . Even so, the greatest demand for fuels comes from the electrical supply industry which dominates the market, and not from individual consumers. 

A tapered block copolymer containing 75 percent butadiene and 25 percent styrene, marketed as Solprene 1205, was the first solution copolymer produced commercially by Phillips in 1962. 

GR-S employs styrene as the minor ingredient with butadiene, and it will be discussed under the heading of the latter compound. Copolymers in which styrene is the major component—i.e., about 70 to 85 parts of styrene with 30 to 15 parts of butadiene— are also produced (23), and they have found markets both as a solid in applications such as shoe soling and floor covering and in latex form as an emulsion paint for inside use. Latex paints (19) of this type have been introduced to the consumer market only within the last few years, but they are receiving widespread acceptance as a result of their excellent film properties, good covering power, and ease of application. 

Plasticizers are used in combination with cellulosics, vinyls, acrylic, and styrene resins, as well as polyvinylacetate, polyamides, polycarbonate, and other synthetic and natural resins. Because PVC consumes about 70% of all plasticizers produced, the plasticizer market is closely related to the vinyl resins production. During the last ten years, the vinyl market grew at an average rate of 18% per year and has reached 1.6 billion pounds in 1964. The growth in vinyl resins and plasticizer production was paralleled by a drop in resin price and a shift towards more effective and less expensive plasticizers. 

Styrene-butadiene rubber (SBR) accounts for about 40 percent of the total consumption of butadiene. SBR is the material used to make most automobile tires. Other synthetic rubbers, such as polybutadiene and poly-chloroprene (neoprene), make up another 25 percent of the butadiene market. 

ABS resin (acrylonitrile-butadiene-styrene) is a widely used terpolymer that accounts for about 8 percent of the butadiene market. 

High cis- 1,4-poly butadiene is manufactured on a large industrial scale and occupies a well-defined position in the elastomers market. It is employed mainly in the tyre industry, where it is blended with natural rubber and/or with styrene-butadiene rubber and applied in either sidewalls, threads or rims of tyres. It should be noted in this connection that natural rubber, in contrast to its synthetic counterpart, displays some physical properties that appear to be useful in the manufacture of tyres for heavy-duty machines. The fact is that some non-hydrocarbon substances appearing in natural rubber in small amounts (such as polypeptides) protect the high-dimensional tyre formed against collapsing prior to the vulcanisation process and thus enable a high-quality product to be obtained. 

For the packaging of sensitive foods, PP films are coated with polyvinylidene chloride, polyvinyl acetate, EVAcopolymers, polyacrylates, styrene-butadiene copolymers, LDPE, poly-l-butene or random copolymers of propene with ethylene and 1-butene. By using these various coatings PP has recently sharply reduced the use of regenerated cellulose (cellophane), the previous market leader in this area. 

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