Phthalate additives

Stalling and coworkers (11) studied the metabolism of DEHP and dibutyl phthalate by channel catfish liver microsomes. They found that the respective monoesters and more polar metabolites were produced, but that DEHP was metabolized to a much lesser extent than dibutyl phthalate. Additional studies (Table V) showed that the production of the respective monoesters was unaffected by the presence of NADPH, but that the production of more polar metabolites is very dependent upon NADPH. The reasons for the apparent lack of a requirement for oxygen are unclear... 

The first report included an analysis of 27 chemicals for 1999 the second, released in 2002, included an analysis of 116 chemicals for 1999-2000, including the 27 from the first report (CDC 2003). The third report, released in July 2005, includes 148 chemicals for 2001-2002 (CDC 2005). The analytes measured in the third report are listed in Table 2-1. The third report includes newly established biomarkers (phthalates), lower limits of detection (of dioxins, furans, and PCBs), and reference ranges for chemicals not previously monitored (pyrethroid insecticides, phthalates, additional dioxins, PCBs, and other pesticides and herbicides). 

Figure 3.5 Effect of membrane composition on electrical conductivity and transport number of cation exchange membrane prepared by the paste method. (O, O) transport number ( , ) specific conductivity. DVB divinylbenzene St styrene PVC poly(vinyl chloride). Composition DVB/(St + DVB) — 0.1 (by weight) numbers in the figure are DOP/PVC (DOP dioctyl phthalate -additives) (by weight). The copolymer membrane is sulfonated with concentrated sulfuric acid.

A variety of non-cyanoacrylate-based modifiers have also been proposed over the last two decades. Some of the earliest of these were the dialkenyl phthalates. Addition of 1-25% concentrations of the phthalate ester to the cyanoacrylate was claimed to improve wet heat resistance. A similar type of heat durability promoter consists of acrylate or methacrylate esters of phosphonates, polyols, or cyanuric acid. Here too, the improvement in heat resistance depends upon curing at elevated temperature, presumably to form a network of the additive, which may also coreact radically with the cyanoacrylate. The use of such additives results in improved heat resistance at 1-20% concentrations. 

In the calendering method, a PVC compound which contains plasticizers (qv) (60—120 phr), pigments (qv) (0—10 phr), fillers (qv) (20—60 phr), stabilizers (10—30 phr), and other additives, is kneaded with calender roUs at 150—200°C, followed by extmsion between clearance-adjusted roUs for bonding onto the substrate. This method is employed for products with thick PVC layers, ie, of 0.05—0.75 mm thickness. The main plasticizer used is di-2-ethylhexyl phthalate (DOP). For filler to reduce cost, calcium carbonate is mainly used. A woven or knit fabric made of cotton, rayon, nylon, polyester, and their blend fiber is used as substrate. For foamed vinyl-coated fabrics, the bonded materials are heated in an oven to decompose the foam-blowing... 

Phosphate Esters. The principal advantage of phosphate esters is the improved fire retardancy relative to phthalates. The fire performance of PVC itself, relative to other polymeric materials, is very good due to its high halogen content, but the addition of plasticizers reduces this. Consequendy there is a need, in certain demanding appHcations, to improve the fire-retardant behavior of dexible PVC. 

The Hildebrand Solubility Parameter. This parameter, 4 can be estimated (10) based on data for a set of additive constants, E, for the more common groups ia organic molecules to account for the observed magnitude of the solubiHty parameter d = EE/V where Erepresents molar volume. SolubiHty parameters can be used to classify plasticizers of a given family ia terms of their compatibihty with PVC, but they are of limited use for comparing plasticizers of differeat families, eg, phthalates with adipates. 

Plasticizer Efficiency. This is a measure of the concentration of plasticizer required to impart a specified softness to PVC. Such a softness of material may be measured as a British Standard Softness (BSS) or a Shore hardness (Pig. 1). Por a given acid constituent of plasticizer ester, ie, phthalate, adipate, etc, plasticizer efficiency decreases as the carbon number of the alcohol chain increases, eg, for phthalate esters efficiency decreases in the order DBP > DIHP > DOP > DINP > DIDP > DTDP. An additional six parts per hundred in PVC of DIDP rather than DOP is required to give a hardness of Shore 80 when ah. other formulation ingredients remain constant. The consequence of this depends on the overall formulation and product costs. In addition to size of the carbon number of the alcohol chain, the amount of branching is also significant the more linear isomers are of greater efficiency. 

Comparison of these environmental compartment concentrations with the actual measurements made at a variety of locations show reasonable agreement but indicate that emission estimates are rather high. It is likely that the fault Hes with worst case estimates for losses from outdoor appHcations and the washing of PVC flooring. In addition a large proportion of the phthalates lost by these routes will not enter rivers because they will be removed by wastewater treatment plants. 

Ahyl alcohol undergoes reactions typical of saturated, aUphatic alcohols. Ahyl compounds derived from ahyl alcohol and used industriahy, are widely manufactured by these reactions. For example, reactions of ahyl alcohol with acid anhydrides, esters, and acid chlorides yield ahyl esters, such as diahyl phthalates and ahyl methacrylate reaction with chloroformate yields carbonates, such as diethylene glycol bis(ahyl carbonate) addition of ahyl alcohol to epoxy groups yields products used to produce ahyl glycidyl ether (33,34). 

In addition to the fundamental property of particle si2e (and surface area), carbon black possesses a secondary characteristic of stmcture, best described as the tendency of individual particles to agglomerate or associate with one another. These two properties or characteristics of the carbon control the degree and nature of the reinforcing character of the black in mbber. The stmcture of the carbon black is deterrnined by dibutyl phthalate absorption and surface area is estimated by N2 absorption (Table 10). 

The alkoxy titanate compounds formed by reaction of one mole of tetraalkyl titanate with one mole of a dialkanolamine are excellent esterification catalysts for the manufacture of phthalate-based plasticizers (112). If a 1 1 molar mixture of alkanolamine and water is used ia place of the alkanolamine, oligomeric titanate complexes are formed, which have high catalyst activity and can be used as thixotropic additives to paints and other aqueous coating formulations (113). 

Additional commercial markets for 1-butanol include plasticizer esters (eg, dibutyl phthalate), butylated melamine—formaldehyde resins, and mono-, di-, and tributylamines. 

The octylphenol condensate is used as an additive to lubricating oils and surface-active agents. Other uses of dimer are amination to octylamine and octyldiphenylamine, used in mbber processing hydroformylation to nonyl alcohol for phthalate production and carboxylation via Koch synthesis to yield acids in formulating paint driers (see Drying). 

The majority (92% in 1988) of the butyraldehyde produced in the United States is converted into 1-butanol and 2-ethyIhexanol (2-EH). 2-EH is most widely used as the di(2-ethylhexyl) phthalate [117-81-7] ester for the plasticisation of flexible PVC. Other uses for 2-EH include production of intermediates for acryflc surface coatings, diesel fuel, and lube oil additives (24). 

Unsaturated polyester resin powders can provide a colored and finished exterior molded surface or a finish ready for painting. Normally, a primer/sealer must be appHed to molded articles prior to painting. In addition to the unsaturated polyester resin, multifimctional unsaturated monomers such as triaHyl cyanurate (TAC) [101-37-1] or diaHyl phthalate (DAP) [131-17-9] suitable peroxide initiators (qv) or mixtures thereof, and mold release agents (qv) are used to formulate the coating powder (46). 

A great variety of resia formulations is possible because other thermosets, such as epoxies or acrylates, and reactive diluents, such as o-diaUyl phthalate [131-17-9] triaUyl cyanurate [101-37-17, or triaUyl isocyanurate [1023-13-6J, can be used to further modify the BT resias. The concept is very flexible because bismaleimide and biscyanate can be blended and copolymerized ia almost every ratio. If bismaleimide is used as a major constituent, then homopolymerization of the excess bismaleimide takes place ia addition to the copolymerization. Catalysts such as ziac octoate or tertiary amines are recommended for cure. BT resias are mainly used ia ptinted circuit and multilayer boards (58). 

The polysulfide base material contains 50—80% of the polyfunctional mercaptan, which is a clear, amber, sympy Hquid polymer with a viscosity at 25°C of 35, 000 Pa-s(= cP), an average mol wt of 4000, a pH range of 6—8, and a ntild, characteristic mercaptan odor. Fillers are added to extend, reinforce, harden, and color the base. They may iaclude siUca, calcium sulfate, ziac oxide, ziac sulfide [1314-98-3] alumina, titanium dioxide [13463-67-7] and calcium carbonate. The high shear strength of the Hquid polymer makes the compositions difficult to mix. The addition of limited amounts of diluents improves the mix without reduciag the set-mbber characteristics unduly, eg, dibutyl phthalate [84-74-2], tricresyl phosphate [1330-78-5], and tributyl citrate [77-94-1]. 

In an attempt to generate (214), a derivative of the elusive monocyclic azete system cf. Section 5.09.5.3.1), the fused 1-azetine (213) was pyrolyzed, but gave only intractable tars in addition to low yields of dimethyl phthalate (71JOC435). 

In addition to their endocrine disrupting properties, it must be appreciated that many of the chemicals in question possess more general toxic properties, which may be potentiated by metabolism by the organism. Several PAHs, PCBs and PCDDs are carcinogenic, while certain phthalate esters can enhance the excretion of zinc, potentially leading to zinc deficiency. Zinc, an essential element, plays a vital role in spermatogenesis and mature T-cell production. Deficiency may result in abnormalities of the male reproductive system, depletion of spermatogenesis and suppression of the immune system. 

Other derivatives can be prepared by reaction of the alcohol with an acid anhydride. For example, phthalic or 3-nitrophthalic anhydride (I mol) and the alcohol (Imol) are refluxed for half to one hour in a non-hydroxylic solvent, e.g. toluene or alcohol-free chloroform, and then cooled. The phthalate ester crystallises out, is precipitated by the addition of low boiling petroleum ether or is isolated by ev toration of the solvent. It is recrystallised from water, 50% aqueous ethanol, toluene or low boiling petroleum ether. Such an ester has a characteristic melting point and the alcohol can be recovered by acid or alkaline hydrolysis. 

---