Diisocyanate MDI

RELATIVE VOLATILITIES OF SOME COMMON INDUSTRIAL DIISOCYANATES 

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Similarly, nitroben2ene, carbon monoxide, and methanol can react sequentially in the presence of noble metal catalysts, to produce methyl A/-phenylcarbamate [2603-10-3] (4). The phenylcarbamate is subsequently coupled with formaldehyde [50-00-0] to yield the methylenebis(carbamate) (5) which is pyroly2ed to yield methylene diphenyl diisocyanate (MDI) (23). 

For methylene diphenyl diisocyanate (MDI), the initial reaction involves the condensation of aniline [62-53-3] (21) with formaldehyde [50-00-0] to yield a mixture of oligomeric amines (22, where n = 1, 2, 3...). For toluene diisocyanate, amine monomers are prepared by the nitration (qv) of toluene [108-88-3] and subsequent hydrogenation (see Amines byreduction). These materials are converted to the isocyanate, in the majority of the commercial aromatic isocyanate phosgenation processes, using a two-step approach. 

A different diisocyanate used in polyurethane synthesis is methylene diisocyanate (MDI), which is prepared from aniline and formaldehyde. The diamine product is reacted with phosgene to get MDI. 

Maleamic acid, cyclization of, 293 Maleic anhydride, 59 Maleimido azine, 307 Manganese diacetate catalysts, 71 Mark-Houwink-Sakurada equation, 57 Material safety data sheets (MSDSs), 246 Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), 385, 388 McGrath, J. E., 327 MDI isomers, 210 MDIs. See Methylene diphenyl diisocyanates (MDIs)... 

Methylene diphenyl diisocyanates (MDIs), 201, 219. See also MDI isomers liquefied, 211, 226-227 Methyl placement, precise versus random, 447... 

Phenolic-isocyanates (phenolic-urethanes). The binder is supplied in three parts a phenolic resin in an organic solvent (0.8%), methylene diphenyl diisocyanate (MDI) (0.5%), and a liquid amine catalyst. When mixed with sand, the amine causes a reaction between the resin and the MDI, forming urethane bonds, which rapidly set the mixture. The speed of setting is controlled by the type of catalyst. The optimum cure temperature is 25 to 30°C. Compression strength is typically over 4000kPa (600psi). 

A number of studies have dealt with the photo-induced discoloration and degradation of polyurethanes based on aromatic diisocyanates such as toluene diisocyanate (TDI - represents a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate isomers) and methylene 4,4-diphenyl diisocyanate (MDI) Cl, 2, 3,... 

Di-hydroxyl end-capped PPG (18) is an intermediate in the formation of a common polyurethane prepolymer (20). End group functionality of this intermediate is important, as this hydroxyl functionality is modified to form the prepolymer. Any different end group structures could lead to the presence of prepolymer that will not form polyurethane of the desired structure. The desired reaction of the intermediate (18) to form the prepolymer (20) is described in Figure 21. Reaction of one unit of the intermediate (18) and two units of methylene diphenyl 4,4 -diisocyanate (MDI) results in the formation (nominally) of the prepolymer (20). 

Isocyanates are capable of co-reacting to form dimers, oligomers and polymers. For example, aromatic isocyanates will readily dimerize when heated, although the presence of a substituent ortho to the -NCO group reduces this tendency. For example, toluene diisocyanate (TDI) is less susceptible to dimer formation than diphenylmethane diisocyanate (MDI). The dimerization reaction is reversible, with dissociation being complete above 200 °C. It is unusual for aliphatic isocyanates to form dimers, but they will readily form trimers, as do aromatic isocyanates. The polymerization of aromatic isocyanates is known, but requires the use of metallic sodium in DMF. 

PCL-diol and diphenylmethane-i -diisocyanate (MDI), by R. delemar lipase were examined. These polyurethanes have both the hydrogen bonds among polymer chains and aromatic rings in the polymer molecules. R. delemar lipase could hydrolyze the polyurethanes though the rate of hydrolysis toward polyurethanes decreased as compared to that ward PCL-diol. The rate of hydrolysis decreased with decreasing the Mn of PCL-moiety of polyurethanes (Figure T). 

We have prepared and characterized three linear isosorbide containing polyurethanes with toluene diisocyanate (TDI), 4,4 -diphenylmethane diisocyanate (MDI), and 1,6-hexamethylene diisocyanate (HMDI) P(I-TDI), P(I-MDI), and P(I-HMDI). These polyurethanes have been synthesized as described in the experimental section by solution polymerization of isosorbide with the corresponding diisocyanate in dimethylacetamide using dibutyl-tin dilaurate as the catalyst at 75 C for 24 hours. All polymers have been isolated in quantitative yield by precipitation in methanol or water (5). 

A study in mice examined immune responses following topical exposure to three allergenic diisocyanates diphenylmethane-4,4 -diisocyanate (MDI), dicyclohexyl-methane-4,4 -diisocyanate (HMDI), and isophorone diisocyanate (IPDI). Contact and respiratory sensitizers induce differential immune responses in mice characteristic of Thl and Th2 T helper cell activation, respectively. All three chemicals are contact allergens. MDI is, in addition, a known human respiratory allergen. HMDI and IPDI did not produce an immunologic response in the mouse similar to MDI. These findings suggest that HMDI has much less potential to cause respiratory sensitization in humans than does MDI ... 

World Health Organization Concise International Chemical Assessment Document(CICAD) 21 Diphenylmethane Diisocyanate (MDI), pp 1-25. International Programme on Chemical Safety (IPCS), Geneva, 2001... 

Embryotoxicity study of monomeric 4,4 -methylenediphenyl diisocyanate (MDI) aerosol after inhalation exposure in Wistar rats. Fundam Applied Toxicol 32 96-101, 1996... 

Uses. Production of methylene diphenyl diisocyanate (MDI), which is used to produce polyurethanes hardening agent for epoxy resins, anticorrosive materials, printed circuit parts, dyestuff intermediates, filament-wound pipe, and wire coatings... 

The uses of aniline obtained from nitrobenzene are given in Table 11.5. Aniline s use in the rubber industry is in the manufacture of various vulcanization accelerators and age resistors. By far the most important and growing use for aniline is in the manufacture of jP,jP-methylene diphenyl diisocyanate (MDI), which is polymerized with a diol to give a polyurethane. 

Major uses of aniline include -methylene diphenyl diisocyanate (MDI) (75%) and rubber chemicals (15%) production. It is also used to a smaller extent in herbicides (4%), dyes and pigments (3%), and specialty fibers (2%). 

A synthetic approach to poly(ester-urethanes) was recently published by Xue et al. [48]. Glycerol was employed as a trifunctional initiator in the enzymatic ROP of CL. The three-arm PCL triol was then reacted with methylene-diphenyl diisocyanate (MDI) and hexanediol to yield a three-arm PCL-based poly(ester-urethane) with shape-memory properties. 

Polyurethanes (PU s). SL and 4,4 -diphenylmethane diisocyanate (MDI) were dissolved in tetrahydrofuran (THF), and the solution was stirred for 1 hr at 60°C. A THF solution of polyethylene glycol (PEG 400) and diethyl bis(2-hydroxyethyl)aminomethylphosphonate (polyol containing phosphorous) was added to the reaction mixture, and the reaction time was extended for 1 hr. In all reactions, the molar ratio of the total amount of isocyanate groups to the total amount of hydroxyl groups (NCO/OH) was maintained at 1.2. The lignin content in PU was 20 wt%. Each solution was drawn on a glass plate, and allowed to dry for 48 hr. The residual solvent in a sample was removed under vacuum and curing of each PU film was carried out at 120°C for 3 hr under a pressure of 50 kg/cm2. 

We observed in a previous investigation of PU s derived from a kraft lignin (KL)-polyether triol-diphenylmetane diisocyanate (MDI) system (Yoshida, H. Morck, R. Kringstad, K. P. Hatakeyama, H., submitted to J. Appl Polym. Set.) that KL fractions of low molecular weight yielded more flexible and less crosslinked PU s than the medium and high molecular weight KL fractions. This was attributed to the lower functionality of the low molecular weight KL fractions. 

HDI is one of the most commercially important isocyanate compounds currently used in the United States. HDI, toluene diisoeyanate (TDI) and 4,4 -diphenylmethane diisocyanate (MDI) are widely used in... 

Important commercial isocyanates include the diisocyanate monomers toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and MDI-, TDI-, and HDI-based isocyanates (e.g., prepolymers and polyisocyanates). World-wide production volume is estimated at over 12 billion lb. Isocyanates (diisocyanates, polyisocyanates, and prepolymers) all cause similar health effects, most commonly asthma [32]. Isocyanates are reported to be the leading attributable cause of work-related asthma [16]. Isocyanates are potent sensitizers that can trigger a severe and potentially fatal asthma attack in sensitized persons at very low isocyanate exposure levels [16]. Toluene diisocyanate is reasonably anticipated to be a human carcinogen by National Toxicology Program. 

We collaborated with Professor Palligamai Vasudevan of the Chemical Engineering Department of the University of New Hampshire on a study of immobilization of lipases on CoFoam. Immobilization was performed at the Hydrophilix facility in Portland, ME. Approximately 2 g lipase (from porcine pancreas and Mucor miehei) were stirred into 500 ml deionized water. The enzyme solution was emulsified with an equal volume of a methylene diisocyanate (MDI)-based hydrophilic polyurethane... 

Synonyms Bis(l,4-isocyanatophenyl)methane diphenylmethane diisocyanate MDI methylenedi-/ ara-phenylene isocyanate and for 26447-40-5 crude MDI polymeric MDI PMDI generic MDI non-isomeric-specific MDI... 

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