Hydrogenated MDI (H₁₂MDI or 4,4′-diisocyanato dicyclohexylmethane) is an organic compound in the class known as

isocyanate In organic chemistry, isocyanate is the functional group with the formula . Organic compounds that contain an isocyanate group are referred to as isocyanates. An organic compound with two isocyanate groups is known as a diisocyanate. Diisocyan ...

s. More specifically, it is an

aliphatic In organic chemistry, hydrocarbons ( compounds composed solely of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (; G. ''aleiphar'', fat, oil). Aliphatic compounds can be saturated, like hexane, or ...

diisocyanate. It is a water white liquid at room temperature and is manufactured in relatively small quantities. It is also known as 4,4'-methylenedi(cyclohexyl isocyanate) or methylene bis(4-cyclohexylisocyanate) and has the formula CH₂ C₆H₁₀)NCOsub>2.

Manufacture

The product is manufactured by

hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a Catalysis, catalyst such as nickel, palladium or platinum. The process is commonly employed to redox, reduce or S ...

methylene diphenyl diisocyanate Methylene diphenyl diisocyanate (MDI) is an aromatic diisocyanate. Three isomers are common, varying by the positions of the isocyanate groups around the rings: 2,2′-MDI, 2,4′-MDI, and 4,4′-MDI. The 4,4′ isomer is most widely used, and i ...

. It may also be manufactured by phosgenation of 4,4-Diaminodicyclohexylmethane.

Uses

Aliphatic diisocyanates are not used in the production of

polyurethane foam Polyurethane products have many uses. Over three quarters of the global consumption of polyurethane products is in the form of foams, with flexible and rigid types being roughly equal in market size. In both cases, the foam is usually behind othe ...

as the cost is too high and foam is very much a commodity. It is used in special applications for

polyurethane Polyurethane (; often abbreviated PUR and PU) refers to a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethan ...

, such as enamel coatings which are resistant to abrasion and degradation from

ultraviolet light Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

. There are also multiple patents where prepolymers based on it are used in golf ball production. It is available commercially under the tradename of Desmodur W from Covestro - formerly Bayer Material Science. It is used as a reactive building block for the preparation of other chemical products such as isocyanate terminated prepolymers and other urethane polymers. The isocyanate groups can undergo addition reactions at room temperature with compounds which contain active hydrogens especially

amines In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such ...

and polyols. Polyurethane resins based on this diisocyanate have good flexibility and mechanical strength. The polymers formed tend to have abrasion and hydrolysis resistance as well as retaining gloss and physical properties upon weathering. The resins based on this material are useful in coatings for flooring, roofing, maintenance and adhesives, and sealants. They find use in the

coatings A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. The purpose of applying the coating may be decorative, functional, or both. Coatings may be applied as liquids, gases or solids e.g. Powder ...

adhesives Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advant ...

sealants Sealant is a substance used to block the passage of fluids through openings in materials, a type of mechanical seal. In building construction ''sealant'' is sometimes synonymous with ''caulking'' and also serve the purposes of blocking dust, so ...

and

elastomers An elastomer is a polymer with viscoelasticity (i.e. both viscosity and elasticity) and with weak intermolecular forces, generally low Young's modulus and high failure strain compared with other materials. The term, a portmanteau of ''elastic po ...

(CASE) applications. A prepolymer made from H₁₂MDI and incorporating dimethylol propionic acid can also be converted to light stable

polyurethane dispersion Polyurethane Dispersion, or PUD, is understood to be a polyurethane polymer resin Dispersion (chemistry), dispersed in water, rather than a solvent. Its manufacture involves the synthesis of polyurethanes having carboxylic acid functionality or non ...

References

{{reflist Isocyanates Monomers Cyclohexanes Organic compounds

Manufacture

Uses

See also

References