TMXDI

HMD was originally produced by Du Pont as a coproduct in the manufacture of Qiana fiber. Du Pont subsequently sold the product to Bayer. In the 1990s MDA is hydrogenated by Air Products for Bayer (see Amines, aromatic-methylenedianiline). Commercial HMDI is a mixture of three stereoisomers. Semicommercial aUphatic diisocyanates include /n j -cyclohexane-l,4-diisocyanate (CHDI) and y -tetramethylxylylene diisocyanate (TMXDI). A coproduct in the production of TMXDI is y -isopropenyl-a,a-dimethylben2yl isocyanate (TMI), which can be copolymerized with other olefins to give aUphatic polyisocyanates. 

An example of the importance of free-volume availabiUty on cross-linking has been reported in the evaluation of a trifunctional derivative of an ahphatic isocyanate which contains an aromatic ring, y -tetramethylxyUdene diisocyanate (TMXDI) [2778-42-9] C 4H N202, as a cross-linking agent for hydroxy-functional resins (15). 

Because of steric effects, TMXDI is less reactive than the trifunctional derivatives of hexamethylene diisocyanate (HDI) (1,6-diisocyanatohexane)... 

Diisocyanates such as p-TMXDI do not form allophanates. This adds to their very stable storage life, even at slightly elevated temperatures. The... 

TMXDI TPU Triol Trowelable An abbreviation for meta-tetramethylxylene diisocyanate. Thermoplastic polyurethane. A polyol containing three reactive hydroxyl groups. Capable of being applied using a trowel and having thixotropic... 

An offering by Cytec Specialty Chemicals, the meta isomer of tetramethyl xylene diisocyanate (TMXDI) is interesting because it contains an aromatic ring, but the NCO groups themselves are aliphatic isocyanates and have reaction characteristics typical of aliphatic diisocyanates. It reacts even more sluggishly than the more standard aliphatic isocyanates because of steric interactions, making the reactions easier to control. Compounds such as dimethyl tin dilaurate, lead octoate, or tetrabutyl diacetyl distannox-ane have been shown to be effective catalysts for the isocyanate-hydroxyl reaction. The manufacturer claims that it is less toxic than many other isocyanates. 

In addition, American Cyanamid Co. has commercialized tetra-methyl xylene diisocyanate (TMXDI) in meta and para forms (117). The synthetic method is shown by the model reactions (1) to (3) as shown below. The NCO-groups are produced by the thermal dissociation of urethane groups. Recently, another similar method was disclosed by the same company (149). The NCO groups are also produced by the thermal dissociation of urethane groups. 

Other high growth aliphatic isocyanates currently in production include isophorone diisocyanate IPDI (4,1) ex. Hiils, hydrogenated MDI HMDI (4.2) ex. Mobay, tetramethyl xylene diisocyanate TMXDI (4,3) and (4.4) ex. American Cyanamid and 3-isopropenyl dimethylbenzyl isocyanate TMI (4.5) ex. American Cyanamid [63a]. The latter two... 

Figure 3.38 Nonaromatic isocyanates, (a) m-Xylenediisocyanate, Sherwin-William s MXDI (b) p-Xylenediisocyanate, Takeda s XDI (c) Tetramethyl-m-xylenediisocyanate, Cyanamid s TMXDI (d) Tetramethyl-p-xylenediisocyanate, (e) isopropenyldimethyl-benzylisocyanate, Cyanamid s TMI.

Benzene, 1,3-bis(1-isocyanato-1-methylethyl)- BRN 2811946 EINECS 220474-4 Isocyanic acid, a,a,a, a -tetramethyl-m-xylylene Isocyanic acid, m-phenylene-diisopropylidene ester, m-Tetramethylxylene diisocyan-ate m-TMXDI Tetramethyl-m-xylylene diisocyanate. 

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