Isophorone diisocyanate

A trend ia the utihty of isophorone is as an important iadustrial building block. Foremost among these developments has been the use of isophorone as a raw material, and isophorone diisocyanate [2855-13-2] (IPDl), for the production of the light-stable polyurethane. The U.S. market for IPDl-based products was 31 million ia 1989, and is estimated to grow to 53 million ia 1994 (230). 

For environmental reasons there has been interest in methods for manufacturing isocyanates without the use of phosgene. One approach has been to produee diurethanes from diamines and then to thermal eleave the diurethanes into diisocyanates and alcohols. Although this method has been used for the production of aliphatic diisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate, for economic reasons it has not been adopted for the major aromatic isocyanates MDI and TDI. 

Isophorone diisocyanate Isopropoxyethanol Isopropyl acetate Isopropyl alcohol Isopropylamine N-lsopropylaniline Isopropyl chloroformate Isopropyl ether... 

Isocyanate is added to provide an equivalent ratio of 1.5-2 isocyanatc/alcohol. The higher the ratio, the more free isocyanate, and diisocyanate monomer, and the lower the viscosity. Most common is 4,4 -methylene bisphenyl diisocyanate (MDl). Its saturated analog or other aliphatic isocyanates are used where light stability is critical. Most common is isophorone diisocyanate. 

In certain niche applications, aliphatic isocyanates, such as isophorone diisocyanate (IPDI), hexamethylene diisoeyanate (HDI), methylene 4,4 -biscyclo-hexylisocyanate (H12MDI), and polymeric versions of these diisocyanates, are used, e.g., in instances where light stability or reduced reactivity is needed. These isocyanates usually cost more than the aromatic diisocyanates. Thus, they are used in adhesive areas that can Justify the higher costs. 

Polyurethane dispersions (PUD s) are usually high-performance adhesives based on crystalline, hydrophobic polyester polyols, such as hexamethylene adipate, and aliphatic diisocyanates, such as methylene bis(cyclohexyl isocyanate) (H12MDI) or isophorone diisocyanate (IPDI). These PUD s are at the more expensive end of the waterborne adhesive market but provide excellent performance. 

Type II Urea-Urethane Oligomers. To 11.6g (0.1 mole) of melted 1,6-hexanediamine was added 76.9g of t-butanol half-blocked isophorone diisocyanate. During about a 30-minute addition, the temperature rose to 50-60°C. After an additional one hour of heating at 50-60°C, the oligomer solution was thinned with 40g of 2-hexoxy-ethanol. 

Hydroxy-terminated polyester (HTPS) is made from diethylene glycol and adipic acid, and hydroxy-terminated polyether (HTPE) is made from propylene glycol. Hydroxy-terminated polyacetylene (HTPA) is synthesized from butynediol and paraformaldehyde and is characterized by acetylenic triple bonds. The terminal OH groups of these polymers are cured with isophorone diisocyanate. Table 4.3 shows the chemical properties of typical polymers and prepolymers used in composite propellants and explosives.E4 All of these polymers are inert, but, with the exception of HTPB, contain relatively high oxygen contents in their molecular structures. 

In order to avoid the use of lead compounds on environmental grounds, lithium fluoride (liF) has been chosen to obtain super-rate burning of nitramine composite propellants.P7281 Typical chemical compositions of HMX composite propellants-with and without liF are shown in Table 7.4. The non-catalyzed HMX propellant is used as a reference pyrolant to evaluate the effect of super-rate burning. The HMX particles are of finely divided, crystalline (3-HMX with a bimodal size distribution. Hydroxy-terminated polyether (HTPE) is used as a binder, the OH groups of which are cured with isophorone diisocyanate. The chemical properties of the HTPE binder are summarized in Table 7.5. 

Toxicology. Isophorone diisocyanate (IPDI) is an irritant and sensitizer of the respiratory tract and the skin. 

Clarke CW, Aldons PM Isophorone diisocyanate induced respiratory disease. AustNZJ Med 11 290-292, 1981... 

Lachapelle JM, Lachapelle-Ketelaer MJ Cross-sensitivity between isophorone diamine and isophorone diisocyanate (IPDI). Contact Derm 5 55, 1979... 

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 ... 

A key factor in the preparation of polyurethanes is the reactivity of the isocyanates. Aromatic diisocyanates are more reactive than aliphatic diisocyanates, and primary isocyanates react faster than secondary or tertiary isocyanates. The most important and commercially most readily accessible diisocyanates are aliphatic and colorless hexamethylene-1,6-diisocyanate (HDI), isophorone diisocyanate (IPDI),and aromatic, brownish colored diphenylmethane-4,4 -diiso-cyanate (MDI), 1,5-naphthalenediisocyanate, and a 4 1 mixture of 2,4- and 2,6-toluenediisocyanates (TDI). 

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