Phthalates monohydric alcohol

Uses. Phthabc anhydride is used mainly in plasticizers, unsaturated polyesters, and alkyd resins (qv). PhthaUc plasticizers consume 54% of the phthahc anhydride in the United States (33). The plasticizers (qv) are used mainly with poly(vinyl chloride) to produce flexible sheet such as wallpaper and upholstery fabric from normally rigid polymers. The plasticizers are of two types diesters of the same monohydric alcohol such as dibutyl phthalate, or mixed esters of two monohydric alcohols. The largest-volume plasticizer is di(2-ethylhexyl) phthalate [117-81-7] which is known commercially as dioctyl phthalate (DOP) and is the base to which other plasticizers are compared. The important phthahc acid esters and thek physical properties are Hsted in Table 12. The demand for phthahc acid in plasticizers is naturally tied to the growth of the flexible poly(vinyl chloride) market which is large and has been growing steadily. 

The use of monohydric alcohol esters as PVC plasticizers had its beginning in the decade of the thirties. Plasticization of PVC was first demonstrated by W. D. Semon of B. F. Goodrich(1). Semon s patent gave examples of plasticizers such as dibutyl phthalate and other unrelated compounds. However, the claims were limited to non specific aromatic substances, liquid aromatic nitro compounds, and specific aromatic nitro compounds. The first commercially used plasticizers for PVC were those already available and used as cellulosic plasticizers, such as the monohydric alcohol ester—dibutyl phthalate. 

Still in the forties, butyl benzyl phthalate (BBP) was introduced by Monsanto Co. This ester is based on the monohydric alcohol n-butanol, but the benzyl group is derived from benzyl chloride rather then benzyl alcohol. This route was selected to make possible manufacture of pure coester which showed a better balance of properties than if made from the two alcohols. BBP was destined to make its mark in PVC, particularly in the flooring industry. 

During the fifties there was widespread activity in the oxo process area. Additional branched chain primary monohydric alcohols - isodecyl and tridecyl - were introduced by Exxon Chemical Company. The phthalates of these alcohols were found to be particularly useful in high temperature PVC insulated wire and cable where DTDP, for example, partially replaced the more costly polymerics (j)). 

Meanwhile, lower monohydric alcohols were first made by the oxo process. These included n-propanol, n- and isobutanol and amyl alcohol. In PVC, only one of these assumed any importance -n-butanol - mainly in butyl benzyl phthalate. Dibutyl phthalate (DBP) was by this time considered too volatile for use in PVC in the U.S.(10). The so-called coesters - butyl octyl phthalate (BOP), butyl isodecyl phthalate and butyl cyclohexyl phthalate -have been on and off the market for many years but never achieved major success in the U.S. Dibutyl phthalate/DOP blends and BOP have probably been most successful in Japan. Diisobutyl phthalate is used in Brazil and other South American countries even today, because of its low cost. BOP is also offered in Europe, but as in the U.S., it has not been a major success. One reason could be the wide variability of composition from different suppliers. In fact, some BOP s were merely physical blends of DBP and DOP. 

Hexyl alcohol, a mixture of n- and iso C6 alcohols made via the oxo process by Exxon Chemical Co., started the flow of new monohydric alcohols as intermediates for PVC plasticizers in the sixties. Dihexyl phthalate - the phthalate of this alcohol - is a fast solvator and competes with other fast solvating types in markets such as vinyl flooring and carpet backing. 

As the decade ended, a new monohydric alcohol phthalate based on mixed C7-C9-C11 straight chain and single methyl branched alcohols was introduced by Monsanto Co. The alcohols are produced by the oxo process from straight chain alpha olefins. The phthalate competed directly with 610P, especially in the automotive upholstery market where it gained rapid acceptance. 

Phthalates of Cg-C o average carbon number monohydric alcohols continue to dominate the PVC plasticizer market, and the likely scenario is for this to continue through the eighties. There have been, however, numerous developments which will... 

The use of hydrocarbon plasticizers as partial replacements for monohydric alcohol phthalates may tend to decrease as a result... 

During the early forties flexible PVC use was mainly limited to military applications, including wire and cable, and various film and sheeting applications, etc. With the conclusion of World War II, new markets for PVC developed rapidly. Aside from DOP, which was commercialized in 1940(4), dicapryl phthalate (DCP) was introduced by Rohm and Haas C5), also in the early forties. With the development of plastisols(6), DCP became a plasticizer of choice because of the favorable balance of properties it imparted — especially low viscosity. However, DCP s subsequent growth has been limited since capryl alcohol (octanol-2), a monohydric secondary alcohol, is a by-product of limited volume sebacic acid manufacture. 

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