Toluene-2,4-diisocyanate polyurethanes from

Diisocyanates generally employed with polyols to produce polyurethanes are 2,4-and 2,6-toluene diisocyanates prepared from dinitro-toluenes (Chapter 10) ... 

No by-product is formed from this reaction. Toluene diisocyanate (Chapter 10) is a widely used monomer. Diols and triols produced from the reaction of glycerol and ethylene oxide or propylene oxide are suitable for producing polyurethanes. 

Polyurethanes can be made from toluene diisocyanate and propylene glycol, or more complicated forms of these compounds. Polyurethanes are easy to foam either in flexible or rigid form. 

We have already been introduced to polyurethane chemistry in Chapter 10, Section 2, where we used toluene diisocyanate (TDI) reacting with a diol to give a polyurethane. Polyurethanes derived from MDI are more rigid than those from TDI. New applications for these rigid foams are in home insulation and exterior autobody parts. The intermediate MDA is now on the Reasonably Anticipated to Be Human Carcinogens list and the effect of this action on the market for MDI remains to be seen. The TLV-TWA values for MDA and MDI are some of the lowest of the chemicals we have discussed, being 0.1 and 0.005 ppm respectively. 

Two other derivatives of toluene are the important explosive trinitrotoluene (TNT) and the polyurethane monomer toluene diisocyanate (TDI). TNT requires complete nitration of toluene. TDI is derived from a mixture of dinitrotoluenes (usually 80% o,p and 20% o,o) by reduction to the diamine and reaction with phosgene to the diisocyanate. TDI is made into flexible foam polyurethanes for cushioning in furniture (35%), transportation (25%), carpet underlay (20%), and bedding (10%). A small amount is used in polyurethane coatings, rigid foams, and elastomers. 

Phosgene is a key intermediate used in synthesis of many chemicals, a major one being toluene diisocyanate, a monomer in polyurethanes. Phosgene is made from chlorine and carbon monoxide through the overall reaction... 

Polyurethanes are formed from a diol (e.g., HOCH,CH,OH) and a diisocyanate, a compound with two —N=C=0 groups (e.g., toluene diisocyanate). 

Elastomeric Polyurethanes from a Kraft Lignin—Polyethylene Glycol—Toluene Diisocyanate... 

Toluene diisocyanate is commonly produced as a mixture of the 2,4- and 2,6-iso-niers, that is used as a monomer in the preparation of polyurethane foams, elastomers and coatings, as a cross-linking agent for nylon-6, and as a hardener in polyurethane adhesives and finishes. Polyurethane elastomers made from toluene diisocyanates are used in coated fabrics and clay-pipe seals. Polyurethane coatings made from toluene diisocyanates are used in floor finishes, wood finishes and sealers, and in coatings for aircraft, tank trucks, truck trailers and truck fleets (United States National Library of Medicine, 1997). 

The toxicokinetics of 2,4- and 2,6-toluenediisocyanates in 11 chronically exposed workers at two flexible foam polyurethane production plants have been reported. The toluene diisocyanate concentrations in air varied between 0.4 and 4 pg/m in one plant and in the other between 10 and 120 p-g/m. In one of the plants, the plasma 2,4-toluene diamine levels were 0.4-1 ng/mL before a 4-5-week holiday and 0.2-0.5 ng/mL afterwards. The corresponding plasma levels of 2,6-toluene diamine were 2-6 and 0.5-2 ng/mL, respectively. In the other plant, the plasma 2,4-toluene diamine concentrations were 2-23 ng/mL before the holiday and 0.5-6 ng/mL afterwards and those of 2,6-toluene diamine were 7-24 ng/mL before and 3-6 ng/mL afterwards. The plasma concentrations of 2,4-toluene diamine were 2-24 ng/mL before a 12-day holiday, and 1-14 ng/mL afterwards. The corresponding values for plasma 2,6-toluene diamine were 12-29 and 8-17 ng/mL, respectively. The urinary elimination rates for 2,4-toluene diamine before the holiday were 0.04-0.54 and 0.02-0.18 pg/li afterwards. The corresponding values for 2,6-toluene diamine were 0.18-0.76 pg/li before and 0.09-0.27 pg/h after the holiday. The half-life in urine ranged from 5.8 to 11 days for 2,4- and... 

Fig. 21. Mooney-Rivlin plots (Eq. IV-1) for a chemically crosslinked polyurethane rubber (from polyoxypropyleneglycol, toluene diisocyanate and trimethylol propane). Note the differences in Cx and C2 values in extension and compression...

In addition, Eq. (5.1) should not be applied in systems that exhibit different initial reactivities of functional groups, such as in the copolymerization of double bonds of a particular unsaturated polyester with styrene or in the formation of a polyurethane starting from 2,4-toluene diisocyanate. 

Let us now analyze the application of this technique to the formation of a polyurethane synthesized from toluene diisocyanate (TDI, a mixture of 80% toluene 2,4- diisocyanate and 20% toluene 2,6-diisocyanate, as shown in Fig. 5.15) and a stoichiometric amount of a polyfunctional polyol based on sorbitol, using triethylamine (TEA) as a catalyst (Aranguren and Williams, 1986). 

Hugo, J.M., Spence, M.W. and Iickly, T.D. (2004) Determination of the extractability of Toluene Diisocyanate from commercial polyurethane foams into air. Polyurethanes Technical Conference 2004, Alliance for the Polyurethane Industry, Arlington, pp. 232-5. 

Major uses of aniline include the manufacture of / ,//-methylene diphenyl diisocyanate (MDI), which is polymerized with a diol (HO-R-OH) to give a polyurethane. Two moles of aniline react with formaldehyde to give />,//-methylenedianiline (MDA), which reacts with phosgene to give / ,//-methylene diphenyl diisocyanate. Toluene diisocyanate (TDI) also reacts with a diol to give a polyurethane, but polyurethanes derived from />,//-methylene diphenyl diisocyanate are more rigid than those from toluene diisocyanate. 

Polyurethane foams are manufactured from a diisocyanate, such as toluene diisocyanate (TDI), and a low-molecular-weight polyether such as poly (propylene glycol). 

TG-MS is ideally suited to reveal differences in pressure behaviour during thermal decomposition of materials. This has been illustrated by Mol [144] in TG-MS analysis of toluene diisocyanate (TDI) and methylene bis-4-phenol isocyanate (MDI)-based polyurethanes, where the observed greater increase in pressure for the TDI polyurethane than for the MDI derivative indicates a higher loss of low molecular weight fragments. This is not possible to deduct from the TG curves alone. Such indications are of great... 

Toluene Diisocyanate (TDI) Toluene diisocyanates (2,4- and 2,6 isomers) are produced from toluene diamine derived from dinitrotoluene, which is produced by the nitration of toluene with nitric/sulfuric acid mixtures. TDI is used to make flexible polyurethane foams, elastomers and coatings. 

Polyurethane is also used as a foam, mostly in sheet form as an underlay or middle layer for example in fruit bins. The following starting materials for polyurethane foam can be used polyester with hydroxyl end groups made from adipic acid, diethylene glycol, trimethylol propane as well as polyether based on ethylene oxide and/or propylene oxide with free hydroxyl groups in combination with 2,4-toluene diisocyanate and 2,6-toluene diisocyanate. Stabilizers, dispersants and amines (as catalysts in amounts up to 1.2 %) can be used. 

Table 4.5. Physical properties of polyurethane elastomers prepared from HTPB and 2,4-toluene diisocyanate (TDI) 205)...

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