Linear trimellitate

A.4.2 Wimellitates Except for a very few highly specialized and expensive esters, the trimellitate ester plasticizers currently represent the state of the art in low-volatility monomeric plasticizers. As in the case with phthalates, the branched-chain trimellitate esters are less expensive than the straight-chain/linear trimellitates. Linear trimellitates offer improved low-temperature flexibility and processabihty over their branched counterparts. 

Trimellitate Esters. These materials are produced by the esterification of a range of alcohols with trimellitic anhydride (TMA), which is similar in structure to phthalic anhydride with the exception of the third functionality (COOH) on the aromatic ring. Consequently, esters are produced in the ratio of three moles of alcohol to one mole of anhydride. Common esters in this family are tris-2-ethyhexyl trimellitate (trioctyl trimellitate, TOTM) L79TM, an ester of mixed semilinear C7 and C9 alcohols and L810TM, an ester of mixed linear Cg and C1Q alcohols. 

Low Temperature Performance. The ability of plasticized PVC to remain dexible at low temperatures is of great importance in certain applications, eg, external tarpaulins or underground cables. For this property the choice of the acid constituent of the plasticizer ester is also important. The linear aliphatic adipic, sebacic, and azeleic acids give excellent low temperature flexibility compared to the corresponding phthalates and trimellitates (Fig. 3). 

Plasticizers. Plasticizers are materials that soften and flexibilize inherently rigid, and even brittle polymers. Oiganic esters are widely used as plasticizers in polymers (97,98). These esters include the benzoats, phthalates, terephthalates, and trimellitates, and aliphatic dibasic acid esters. For example, triethylene glycol bis(2-ethylbutyrate) [95-08-9] is a plasticizer for poly (vinyl butyral) [63148-65-2], which is used in laminated safety glass (see Vinyl polymers, poly(vinyl acetals)). Di(2-ethylhexyl)phthalate [117-81-7] (DOP) is a preeminent plasticizer. Variation of acid and/or alcohol components) modifies the efficacy of the resultant ester as a plasticizer. In phthalate plasticizers, molecular sizes of the alcohol moiety can be varied from methyl to tridecyl to control permanence, compatibility, and efficiency branched (eg, 2-ethylhexyl, isodecyl) for rapid absorption and fusion linear (C6—Cl 1) for low temperature flexibility and low volatility and aromatic (benzyl) for solvating. Terephthalates are recognized for their migration resistance, and trimellitates for their low volatility in plasticizer applications. 

Linear PC[23] 1,1,1 -tri(4-hydroxy-phenyl) ethane, 2,2 5,5 -tetra(4-hydroxypheny 1) hexane, trimellitic anhydride, trimellitic acid, trimellitoyl trichloride, 4-chloroformyl phthalic anhydride, pyromellitic acid, pyromellitic dianhydride, mellitic acid, mellitic anhydride, trimesic acid, benzophenonetetracarboxylic acid and benzophenonetetracarboxylic anhydride (0.1-10 % by weight) 100-400 Increased branching and crosslinking... 

Pulmonary haemorrhage associated with haemolytic anaemia has been reported in four men exposed to very high concentrations of heated trimellitic anhydride fumes (Zeiss and Patterson, 1993). Increased total antibody levels were found in these men. Using a rat model it has been shown that there was a linear relationship between antibody concentrations and the degree of pulmonary haemorrhage suggesting that immune mechanisms may play a role in this disorder (Zeiss and Patterson, 1993). 

When trimellitic anhydride (7) is reacted with aminoethanol (9) and this intermediate with propylene glycol and fumaric acid, a linear unsaturated poly(es-ter-imide) is obtained, soluble in 6,6-dimethylfulvene, claimed by the inventors to have good thermal stability after curing [214]. 

PEIs of 4,4 -bisphenol and trimellitic anhydride linked by a linear aliphatic aminoacid (8) form enantiotropic LC-phases but it is the bisphenol unit which predominates to give this behaviour. For n=10 or 11 both smectic and nematic phases are observed [21]. 

Kricheldorf has reported the synthesis of lyotropic poly(amide-imide)s and poly(benzoxazole-amide)s. These were prepared by the polycondensation of N,N-bis(trimethylsilyl)-p-phenylenediamine or N,AT -bis(trimethylsilyl)-3,3 -dim-ethylbenzidine with the diacyl chloride of trimellitimide of p-aminobenzoic acid, or the imide formed from p-amino benzoic acid and terephthalic acid. Lyotropic behaviour was observed in cone, sulphuric acid solution [38]. A series of thermotropic poly(imide-amide)s was prepared based on trimellitimides formed from trimellitic anhydride and an a, -bis(4-aminophenoxy) alkane with carbon chain lengths 9-12. Melting points were in the range 250-300 °C. They formed smectic A phases and tended to degrade around the isotropisation temperatures (around 350 °C). Pendant methyl groups or occupied meta- groups tended to prevent mesophase formation [39]. Novel LC poly(imide-amides) have also been synthesised from new diamine spacers derived from linear diaminoalkanes and 4-nitrophthalic anhydride. A smectic and nematic phase were observed when 4,4 -biphenyl dicarboxylic acid was used as co-monomer [40]. 

Polymer plasticization can be achieved either through internal or external incorporation of the plasticizer into the polymer. Internal plasticization involves copolymerization of the monomers of the desired polymer and that of the plasticizer so that the plasticizer is an integral part of the polymer chain. In this case, the plasticizer is usually a polymer with a low Tg. The most widely used internal plasticizer monomers are vinyl acetate and vinylidene chloride. External plasticizers are those incorporated into the resin as an external additive. Typical low-molecular-weight external plasticizers for PVC are esters formed from the reaction of acids or acid anhydrides with alcohols. The acids include ortho- and iso-or terephthalic, benzoic, and trimellitic acids, which are cyclic or adipic, azeleic, sebacic, and phosphoric acids, which are linear. The alcohol may be monohydric such as 2-ethylhexanol, butanol, or isononyl alcohol or polyhydric such as ethylene or propylene glycol. The structures of some plasticizers of PVC are shown in Table 9.1. 

A few companies have reduced their commitment to polymer additives. The Swiss company Lonza places increasing emphasis on pharmaceutical intermediates in its European operations, but also makes oleochemicals for plastics. Other additive products include plasticisers, both general-pm tose types and linear phthalates, together with polymeries and trimellitates. It is a leading supplier in the US of polymer lubricants such as EBS (ethylene bis-stearamide) and other amide waxes. First half profits overall were down 16% in 2004. Research and development expenditure in 2003 amoimted to US 65 M. A new CEO, Stefan Borgas, has been appointed from BASF. 

Reaction polymerization reactions of isocyanates with suitable monomers can he performed in an extruder or in a RIM machine. In the latter reaction thermosets (cross-hnked polymers) are produced. In an extruder usually linear polymers are manufactured. For example from methylene di-p-phenylene isocyanate (MDI), with some macroglycols and 1,4-hutanediol as extenders, segmented polyurethane elastomers are produced in an extruder (6). However, linear condensation polymers are also produced in a vented extruder. For example from MDI, with macrodicarboxylic acids and dicarboxyhc acids as extenders thermoplastic block copolyamide elastomers are produced. The by-product of the condensation reaction, carbon dioxide, is removed in the vented extruder. The polycondensation process can also be performed in solution. For example, MDI can be added to a solution of dicarboxyhc acids in tetramethylene sulfone, with simultaneous removal of the carbon dioxide. Tetramethylene sulfone is the solvent of choice for solution polymerization of isocyanates (7). In addition to dicarboxyhc acids trimellitic acid anhydride and benzophenonetetracarboxylic acid dianhydride (BTDA) are utilized as monomers for condensation polymers. With these monomers poly(amide imides) and poly(imides) are produced. The diisocyanate-derived commercial polycondensation products are listed in Table 1. 

PlaStiCiZGr Efficiency. This is a measure of the concentration of plasticizer required to impart a specified softness to PVC or shore hardness (Fig. 2). For a given acid constituent of plasticizer ester, ie, phthalate, adipate, etc, plasticizer efficiency decreases as the carhon number of the alcohol chain increases, eg, for phthalate esters efficiency decreases in the order BBP > DIHP > DOP > DINP > DIDP > DTDP (10). In addition to size of the carbon number of the alcohol chain, the amount of branching is also significant the linear plasticizers are more efficient. Choice of the acid constituent can also be significant. For equivalent alcohol constituents, phthalate and adipate esters are both considerably more efficient than their trimellitate eqmvalent. 

Low volatility Polymeries, trimellitates, linear phthalates, epoxy plasticizers... 

The chemistry involved in curable poly(ester imide) formulations is well established, and it is still based on trimellitic anhydride, methylene dianiline, and low molecular weight polyesters of aromatic dicarboxylic acids and glycols, along with a classical heterocyclic triol, 2,4,6-trishydroxyethyl isocyanurate (THEIC), as it is shown in Scheme (29). The composition is formulated in a way that the final polymers, although linear, contain free —OH groups, both as chain ends and as side reactive groups. At the moment of... 

Because of the lower volatility of DIDP and DPHP relative to other GP plasticizers, these two plasticizers are also sometimes considered low-volatility plasticizers. For automotive interior products the plasticizers DEHP, DINP, DEHTP, DC9CH, citrates, benzoates, as well as many of the phthalate alternatives would fail many interior emission or fogging requirements while DIDP and DPHP, along with trimellitate esters and the linear phthalates L9P and L91P, would pass. 

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