Polymethylene diisocyanate

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... 

Sung C.S.P. and Schneider N.S., Infrared studies of hydrogen bonding in toluene diisocyanate based polymethylene, Macromolecules, 8, 68, 1975. 

Uses/Sources. Intermediate in organic synthesis, especially production of toluene diisocyanate and polymethylene poly-phenylisocyanate in metallurgy to separate ores by chlorination of the oxides and volatilization occurs as a product of combustion whenever a volatile chlorine compound comes in contact with a flame or very hot metal originally manufactured as an agent for chemical warfare during World War I... 

Polymethylene polyphenyl isocyanate (see also 4,4 -Methylenediphenyl diisocyanate)... 

Isocyanates Diphenylmethane Diisocyanate Polyphenyl Polymethylene-isocyanate Toluene Diisocyanate... 

Toluene 2,4-diisocyanate (TDI), diphenylmethanediisocyanate (MDI),and polymethylene polyphenyl isocyanate (PAPI) are considered compatible with reactivity groups 9, 10, 11, 12, 18, and 21. 

At least 90 % of the worldwide production of isocyanates is accounted for by two aromatic isocyanates, toluene diisocyanate (TDI), a distilled compound, and polymethylene polyphenylene polyisocyanate (PMDI), an undistilled isocyanate mixture with a low vapor pressure (Structures 1-3). Together these two products cur-... 

Desmocoii 420, Desmocoii 500. See Polyurethane, thermoplastic Desmodur 44 M L Fiakes, Desmodur 44 MC L Liq., Desmodur 2460 M. See MDI Desmodur BL 1100. See Polyurethane resin Desmodur CD. See MDI Desmodur i. See Isophorone diisocyanate Desmodur MP-225. See MDI Desmodur VK-5, Desmodur VK-18, Desmodur VK-70, Desmodur VK-200, Desmodur VKS-2, Desmodur VKS-4, Desmodur VKS-5, Desmodur VKS-18. See Polymethylene polyphenyl isocyanate Desmoiac 2100. See Polyurethane resin Desmopan 150, Desmopan 155, Desmopan 356, Desmopan 359, Desmopan 385, Desmopan 392, Desmopan 445,... 

Other well-established diisocyanates used as adhesive-promoting primers are dianisidine diisocyanate (DADI) and polymethylene polyphenyl isocyanate (PAPI) their structures are given in Fig. 8.5. 

Diphenylmethane diisocyanate (MDI) 1,5-Naphthalene diisocyanate (NDI) Hexamethylene diisocyanate (HDI) Polymethylene polyphenyl isocyanate (PMPI) Isophorone diisocyanate (IPDI) Trimethylhexamethylene diisocyanate (TMDI)... 

The most commonly used difunctional isocyanates are TDI, MDI and 1,6-hexamethylene diisocyanate or 1,6-diisocyanatohexane (HDI). TDI often contains mixtures of the isomers 2,4-TDI and 2,6-TDI. MDI is industrially used as a mixture of 4,4 -MDI with 2,4 -MDI and 2,2 -MD which is also called polymethylene polyphenyl isocyanate (PAPI or PMPPI). Phenyl isocyanate is usually a trace constituent in commercial MDI products. Examples of other diisocyanates include isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), naphthalene diisocyanate (NDI), triphenyl-methane triisocyanate (TPMTI), and DMDI (Malten 1977> 1982, i984a,b, i987a,b Bjorkner 1992 Elvers et al. 1991 Estlander et al. 1992 Karol and Kramarik 1996). 

Methylene bisphenyl-4,4 -diisocyanate Paraphenylene diisocyanate crude Polymethylene polyphenyl isocyanate Toluene-1,3-diisocyanate Toluene-2,4-diisocyanate Toluene-2,4-diisocyanate >70% Toluene-2,6-diisocyanate... 

The most common polyisocyanate used in urethane sealant production is toluene diisocyanate (TDI). The TDI is usually prereacted to give an isocyanate-terminated prepolymer. Other aromatic polyisocyanates used in sealants include diphenylmethane diisocyanate (MDI) and polymethylene polyphenylene isocyanate (PAPI). All of the aromatic poly isocyanates contribute to yellowing of urethanes on exposure to light. 

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