4-4’-diphenylmethane diisocyanate

Monochlorobenzene. The largest use of monochlorobenzene in the United States is in the production of nitrochlorobenzenes, both ortho and para, which are separated and used as intermediates for mbber chemicals, antioxidants (qv), dye and pigment intermediates, agriculture products, and pharmaceuticals (Table 5). Since the mid-1980s, there have been substantial exports of both o-nitrochlorobenzene, estimated at 7.7 million kg to Europe and -nitrochlorobenzene, estimated at 9.5 million kg to the Far East. Solvent use of monochlorobenzene accounted for about 28% of the U.S. consumption. This appHcation involves solvents for herbicide production and the solvent for diphenylmethane diisocyanate manufacture and other chemical intermediates. 

Diphenylmethane diisocyanate, see Isocyanates Methylene bisphenyl isocyanate... 

Adhesives based on isocyanate (especially PMDl, polymethylene diisocyanate, more exactly polymeric 4,4 -diphenylmethane diisocyanate) have been used for more than 25 years in the wood-based panel industry [88], but still have a low market value in the wood-working industry compared to systems based on UF-, MUF- or PF-resins. The main application is the production of waterproof panels, but also the production of panels from raw materials that are difficult to glue, like straw, bagasse, rice shells or sugar cane bagasse. They can be used as adhesives for wood-based products like particleboard, oriented strandboard (OSB), laminated strand lumber (LSL), medium-density fiberboard (MDF) or... 

Add wood furnish (384 g, moisture content 6.02%) to the bowl of a rotary blade paddle mixer (such as a Kitchen-Aid KSM90) and agitate at the lowest speed setting. Add Mondur 541 (7.39 g, 1.9% w/w, a polymeric diphenylmethane diisocyanate of 31.5% NCO, Bayer) dropwise over a 5-min period using a disposable syringe. Continue blending for an additional 10 min and then transfer the blend to an 8 x 8 x 2 -in. metal form at the bottom of which is a metal plate which fits inside. The resin-coated furnish is evenly spread inside the form and another metal plate is placed on top. All parts of the form and plates are presprayed with mold release. The completed form assembly is placed into a hydraulic press (such as a model PW-22 manufactured by Pasadena Hydraulics) with platens heated at 350°F. The furnish is then pressed between the two form plates to a thickness of j in. Press controls are used to ensure consistency of board thickness. The assembly is heated for 4 min. before demolding the cured wood panel. 

The first example of siloxane-urea segmented copolymers were prepared by the direct reaction of aminopropyl-terminated polydimethyl siloxane oligomers and MDI (4,4 -diphenylmethane diisocyanate), in solution at room temperature as shown in the Reaction Scheme XI. 

Figure 6. Analysis (29) according to Eq. 7 of gel-point data (25, 26, 28) from reactions of HDI and diphenylmethane diisocyanate (MDl) with POP trilos (LHT-240, LHTII2) and tetrols (OPPE-NHI, OPPE-NH2-oxypropylated pentaerythri-tols) in bulk and in nitrobenzene solution at 80°C, with cMt = cao + ecosystems 1 and 2, HDI and POP triols 3, MDl and POP triol 4 and 5, HDI and POP tetrols. Key 1, HDI and LHT240, is 33 2, HDI and LHTII2, v is 61 3, MDl and LHT240, v is 30 4, HDI and OPPE-NHI, v is 29 S, HDI and OPPE-NH2, v is 33.

Polyurethane networks were prepared from polyoxypropylene (POP) triols(Union Carbide Niax Polyols) after removal of water by azeotropic distillation with benzene. For Niax LHT 240, the number-average molecular weight determined by VPO was 710 and the number-average functionality fn, calculated from Mjj and the content of OH groupSj determined by using excess phenyl isocyanate and titration of unreacted phenyl isocyanate with dibutylamine, was 2.78 the content of residual water was 0.02 wt.-%. For the Niax LG-56, 1 =2630, fn=2.78, and the content of H2O was 0.02wt.-%. The triols were reacted with recrystallized 4,4"-diphenylmethane diisocyanate in the presence of 0.002 wt.-% dibutyltin dilaurate under exclusion of moisture at 80 C for 7 days. The molar ratio r0H = [OH]/ [NCO] varied between 1.0 and 1.8. For dry samples, the stress-strain dependences were measured at 60 C in nitrogen atmosphere. The relaxation was sufficiently fast and no extrapolation to infinite time was necessary. 

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. 

Engonga, P.E., Schneider, R., Gerardin, P. and Loubinoux, B. (1999). Chemical modification of wood with perfluoroaUcyl ethanol and 4,4 -diphenylmethane diisocyanate. Holzforschung, 53(3), 272-276. 

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). 

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

Burge P Nonspecific bronchial hyperreactivity in workers exposed to toluene diisocyanate, diphenylmethane diisocyanate and colophony. Eur J Respir Dis 63(suppl 123) 91-96, 1982... 

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. 

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... 

Bascom R, Kennedy TP, Levitz D, et al. 1985. Specific bronchoalveolar lavage IgG antibody in hypersensitivity pneumonitis from diphenylmethane diisocyanate. Am Rev Respir Dis 131(3) 463-465. 

Malo JL, Ouimet G, Cartier A, et al. 1983. Combined alveolitis and asthma due to hexamethylene diisocyanate, with demonstration of crossed respiratory and immunologic reactivities to diphenylmethane diisocyanate. J Allergy Clin Immunol 72(4) 413-419. 

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