Tolylene di-isocyanate

A typical polyester could be poly (diethyleneglycol adipate) with a molecular weight of between 2000 and 3000. A typical polyether is obtained by polymerisation of propylene oxide, usually in the presence of a small proportion of glycerol or sorbitol to provide branched structures. Two of the most commonly used isocyanates are 2,4- and 2,6- tolylene di-isocyanate (TDI). These are chosen because of their reactivity, cheapness and relative low toxicity. The resulting prepolymer has -OH terminal groups when a deficiency of isocyanate is used, but -NCO terminal groups if an excess of isocyanate is employed. 

Carroll KB, Secombe CJP, Pepys J (1976) Asthma due to non-occupational exposure to toluene (tolylene) di-isocyanate. Clin Allergy 6 99-104 Cattalini L, Martelli M (1967) Relazione tra reattivita di complessi planari del platino e na-tura del grouppo uscente, in reazioni di sostituzione nucleofila. Gazz Chim Ital 97 498-508... 

Tanser AR, Bourke MP, Blandford AG (1973) Isocyanate asthma respiratory symptoms caused by diphenyl-methane di-isocyanate. Thorax 28 596-600 Taylor GL (1970) Immuno responses to tolylene di-isocyanate (TDI) exposure in man. Proc R Soc Med 63 379-380... 

Chemistry Polyurethane is produced by the reaction of a polyol with an diisocyanate (or in some instances a polyisocyanate) in the presence of catalysts. The polyols of choice are poly(propylene glycol), block copolymers of ethylene oxide (10-15%) with propylene oxide, or the newer polymer polyols (based on polymers such as polystyrene or styrene-acrylonitrile copolymer). Polyester diols such as polycaprolactone diol can be used in place of the polyether polyol in this reaction. The isocyanate of choice is a mixture of the 2,4 and 2,6 isomers of tolylene di-isocyanate in the ratio of 80 20, generally referred to as 80 20TDI. Other isocyanates such as diphenylmethane di-isocyanate (MDI), hexamethylene di-isocyanate (HMDI), and isophorone di-isocyanate (IPDI) are also used. A tin-based or amine catalyst is used to promote the reaction. Given the wide choice of reactants available, the reaction can yield foams with a range of different mechanical and thermal characteristics. 

Di-isocyanate. The di-isocyanate normally used for producing flexible polyurethane foam is an 80 20 (parts by weight) mixture of 2 4 and 2 6 tolylene di-isocyanates (TDI). For some uses a 65 35 mixture of TDI is used. 

SYNS 2,6-DiisocYANATO-i-METHYLBENZENE 2,6-DIISOCYANATOTOLUENE HYI.ENE TM 2-METHYI.-m-PHENYLENE ESTER, ISOCYANIC ACID 2-METHYL-m-PHENYLENE ISOCYANATE NUXTDI 2,6-TDI 2,6-TOLUENE DIISOCYANATE m-TOL- [ LENE DIISOCYANATE TOLYLENE-2,6-DI-ISOCYANATE... 

Toluene 2,4-Diisocyanate. 2,4-Di isocyan atotolu -ene 2.4-tolylene diisocyanate TDI Nacconate 100, CjH -NjOj mol wt 174.15. C 62.07%, H 3.47%, N 16.09%, O 18.37%. Usually prepd from toluene-2,4-diamine and phosgene. Review Astle, Industrial Organic Nitrogen Compounds (New York, 1961) pp 284-313 Faith, Keyes Clark s Industrial Chemicals, F. A. Lowenheim, M. K. Moran, Eds. (Wiley -lntersdenee, New York, 4th ed., 1975) pp 831-835. 

Glucoamylase has been immobilized, with retention of activity, by reaction with cellulose beads treated with tolylene 2,4-di-isocyanate, or with an activated derivative of collagen, or with diazotized 1,4-diaminobenzene in various forms, by glutaraldehyde-coupling to aminoalkylsilyl glass, by glutaralde-... 

Reaction with tolylene 2,4-di-isocyanate derivatives of cellulose beads... 

Reaction with cellulose activated with tolylene- or hexamethylene-2,4-di isocyanate or glutaraldehyde Reaction with cellulose treated with 3-aminopropyltriethoxy-silane followed by glutaraldehyde treatment Adsorption on to diethylaminoethyl- or guanidino-cellulose Glutaraldehyde-crosslinked to Dowex MWA-1... 

Isocyanate Components. Aromatic Di- and Polyisocyanates. The most important monomeric aromatic diisocyanates used for coatings are tolylene diisocyanate (TDI) and 4,4 -methylene bis(phenyl isocyanates) (MDI). Tolylene diisocyanate, a colorless liquid (bp 120 °C at 10 mmHg), is generally used in 80/20 blends of the 2,4-and 2,6-lsomers. Pure 2,4-TDI isomer has also been employed for coatings. 

PU-1. This polyether prepolymer (NCO/OH = 2) was prepared at 80°C under nitrogen. 1.5 equivalent weights of poly (tetramethylene glycol), MW = 661 (PM 660), were slowly added with stirring to three equivalent weights of tolylene diisocyanate (TDI) in a resin kettle. The reaction was allowed to proceed until the theoretical isocyanate content (determined by the di-n-butylamine method) was reached (2 hr). An equivalent weight of a... 

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