Adipic market

Adipic acid is a very large volume organic chemical. Worldwide production in 1986 reached 1.6 x 10 t (3.5 x 10 lb) (158) and in 1989 was estimated at more than 1.9 x 10 t (Table 7). It is one of the top fifty (159) chemicals produced in the United States in terms of volume, with 1989 production estimated at 745,000 t (160). Growth rate in demand in the United States for the period 1988—1993 is estimated at 2.5% per year based on 1987—1989 (160). Table 7 provides individual capacities for U.S. manufacturers. Western European capacity is essentially equivalent to that in the United States at 800,000 t/yr. Demand is highly cycHc (161), reflecting the automotive and housing markets especially. Prices usually foUow the variabiUty in cmde oil prices. Adipic acid for nylon takes about 60% of U.S. cyclohexane production the remainder goes to caprolactam for nylon-6, export, and miscellaneous uses (162). In 1989 about 88% of U.S. adipic acid production was used in nylon-6,6 (77% fiber and 11% resin), 3% in polyurethanes, 2.5% in plasticizers, 2.7% miscellaneous, and 4.5% exported (160). 

About 85% of U.S. adipic acid production is used captively by the producer, almost totally ia the manufacture of nylon-6,6 (194). The remaining 15% is sold ia the merchant market for a large number of appHcations. These have been developed as a result of the large scale availabihty of this synthetic petrochemical commodity. Prices for 1960—1989 for standard resia-grade material have parahed raw material and energy costs (petroleum and natural gas)... 

Polyurethanes. About 3% of the U.S. polyurethanes market in 1988 was derived from the condensation product of polyisocyanates with low molecular weight polyadipates having hydroxyl end groups (195). In 1986 this amounted to 29,000 t, or 4% of total adipic acid consumption. The percentage was similar in Western Europe. About 90% of these adipic acid containing polyurethanes are used in flexible or semirigid foams and elastomers, with the remainder used in adhesives, coatings, and spandex fibers. 

R. T. Gerry, "Adipic Acid" in Chemical Economics Handbook, Marketing Research Report, SRI International, Menlo Park, Calif., 1987, p. 608.5032M. 

Some other phenol derivatives are somewhat local in appHcation. Eor example, aniline is produced from phenol at only two plants, one in Japan and one in the United States. Likewise, phenol is used in the production of nylon, via caprolactam (qv) or adipic acid (qv) by only one United States producer and one European producer. These markets, like the phenoHc resin and polycarbonate markets, are quite cycHcal. Thus, the entire phenol market tends to be cycHcal and closely tied to the housing and automotive markets. 

In the 1940s ICI introduced a material marketed as Vulcaprene made by condensing ethylene glycol, adipic acid and ethanolamine to a molecular weight of about 5000 and then chain extending this with a diisocyanate. This rubbery material found some use as a leathercloth and is dealt with further in Chapter 25. 

A further approach is used by Bayer with their polyesteramide BAK resins. A film grade, with mechanical and thermal properties similar to those of polyethylene is marketed as BAK 1095. Based on caprolactam, adipic acid and butane diol it may be considered as a nylon 6-co-polyester. An injection moulding grade, BAK 2195, with a higher melting point and faster crystallisation is referred to as a nylon 66-co-polyester and thus presumably based on hexamethylene diamine, adipic acid and butane diol. 

Polyurethane dispersions (PUD s) are usually high-performance adhesives based on crystalline, hydrophobic polyester polyols, such as hexamethylene adipate, and aliphatic diisocyanates, such as methylene bis(cyclohexyl isocyanate) (H12MDI) or isophorone diisocyanate (IPDI). These PUD s are at the more expensive end of the waterborne adhesive market but provide excellent performance. 

As well as aiding processing, a major function of plasticisers is to extend the operating temperature range by improving low temperature flexibility. The majority of demand in CR and NBR is satisfied by general purpose phthalate plasticisers di-2-ethylhexyl phthalate (DEHP), diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP). However, a wide variety of speciality plasticisers, mainly esters, are marketed within the rubber industry. The majority of these have linear molecular structures giving them better low temperature performance than the phthalates. Examples of such plasticisers are di-2-ethylhexyl adipate (DOA), butyl carbitol adipate, di(butoxyethoxyethyl) adipate (BCA), and di-2-ethylhexyl sebacate (DOS). 

Nearly all cyclohexane is used to make three intermediate chemicals. About 85% goes for caprolactam, and adipic acid. Another 10% goes for hexamethylene diamine (HMD). All three are the starting materials for Nylon 6 or Nylon 66 synthetic fibers and resins. Nylon fiber markets include the familiar applications hosiery, upholstery, carpet, and tire cord. Nylon resins are engineering plastics and are largely used to manufacture gears, washers, and similar applications where economy, strength, and a surface with minimum friction are important. 

Table 11.3 shows the main uses of cyclohexane. Adipic acid is used to manufacture nylon 6,6, the major nylon used currently in the U.S. Caprolactam is the monomer for nylon 6, for which there is a growing market. 

Table 11.4 gives the uses of adipic acid. As will be seen later, nylon 6,6 has large markets in textiles, carpets, and tire cords. It is made by reaction of HMDA and adipic acid. 

In 1990, DMS introduced nylon-4,6 called Stanyl (structure 19.39), based on the reaction between adipic acid and 1,4-diaminobutane. Stanyl can withstand temperature of about 310°C allowing it to create a niche between conventional nylons and high-performance materials. It was not able to break into the film market and has only now begun to be accepted for tire cord applications. About 22 million pounds of Stanyl was produced in 2001. 

In the recent years, new markets have arisen for biodegradable polymers such as poly(butylene adipate-terephthalate), poly(lactide), poly(butylenesuccinate), or poly(3-hydroxybutyrate) and poly(carbonates). They constitute a new class of green polymers with wide application potential for packaging, clothing, carpets, applications in automotive engineering, foils, and utilities in agriculture. 

In February 1935, a fiber known in the laboratory as fiber 66 was produced that held promise for commercialization. The 66 refers to the number of carbon atoms in the reactants used to produce it. In the case of fiber 66, the two sixes refer to the six carbon atoms in adipic acid and six carbon atom in hexamethylenediamine, H2N(CH2)6NHr Fiber 66 was the first nylon produced. Like rayon, nylon is a generic term used for a group of synthetically produced polyamides. The name nylon was not introduced until 1938 after an extensive discussion by DuPont on what to call fiber 66. There are several versions of how the name nylon was coined, but one claims that nylon was a modification of norun (no run), which was modified into a unique name that could be used to market the product. DuPont officials had hoped to keep the name secret until the 1939 World s Fair, but leaks and patent preparation forced them to reveal the name early. DuPont did not trademark the name, but promoted the material genetically as nylon. 

The nylon filter currently sold as l- xm pore size Nylasorb (Gelman Sciences), probably the most widely used filter for HN03 sampling in the United States, was initially marketed by Ghia Corporation. Until 1985, these filters were fabricated from nylon 6, a polyamide formed from the homopolymerization of e-caprolactam. More recently, Gelman, Sartorius, and other vendors have supplied filters fabricated from nylon 6,6, made by polymerization of adipic acid and hexamethylenediamine. 

Adipic acid historically has been manufactured predominantly from cyclohexane and, to a lesser extent, phenol. During the 1970s and 1980s, however, much research has been directed to alternative feedstocks, especially butadiene and cyclohexene, as dictated by shifts in hydrocarbon markets. All current industrial processes use nitric acid in the final oxidation stage. Growing concern with air quality may exert further pressure for alternative routes as manufacturers seek to avoid NO, abatement costs, a necessary part of processes dial use nitric acid. 

Adipic acid is a very large-volume organic chemical. It is one of the top 50 chemicals produced in the United States in terms of volume. Demand is highly cyclic, reflecting the automotive and housing markets especially. Prices usually follow the variability in crude oil prices. Adipic acid for nylon takes about 60% of U.S. cyclohexane production the remainder goes to caprolactam for nylon-6, export, and miscellaneous uses. 

Other 2-ethylhexanol based plasticizers were introduced, including some which imparted outstanding low temperature flexibility—dioctyl adipate (DOA), dioctyl azelate (DOZ), dioctyl sebacate (DOS), and trioctyl phosphate (TOF). In addition, TOF showed high resistance to microorganisms which was important in military applications. Furthermore, TOF improved flame resistance. However, the mixed ester—octyl diphenyl phosphate—also introduced in the forties—was far superior and showed a better balance of low temperature performance and flame resistance than either TOF or the well-established plasticizer—tricresyl phosphate (TCP). Each of these found a market as a specialty plasticizer because of these specific performance attributes. None, however, was a serious threat to DOP on an overall price-performance basis. Rather, they were used to supplement the properties of DOP where its performance was inadequate. 

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