Trimethylol melamine

Dimethylol cyclic ethylene urea (4) dimethylol methyl triazone (5) and trimethylol melamine methyl ester (6) are also used. 

Polymerization Chemistry. Melamine has six amine hydrogens, all of which can react readily with formaldehyde to produce methylol melamines (Fig. 3.11). For different applications, the degree of methylolation is controlled by the melamine/ formaldehyde ratio, pH, temperature, and time. Polymerization reactions are buffered at pH 8 to 10 by use of sodium earbonate or borax, and polymerization temperature 80 to 100°C. Lower pH and higher temperature produce faster reaction. Trimethylol melamine is most common, but hexamethoxymethyl melamine (HMMM) is popular for coatings, because it is more stable and soluble in organic solvents (Fig. 3.12). 

Fig. 65. Prominent endoplasmic reticulum and ovoid electron-dense secretory granules in the apical cap of a type 4 Clara cell from a bronchiole (block 465) of a male rat (No. 5/104 E) which inhaled 71.5 mg trimethylol melamine (Madurit) dust/1 for a total of 32 h 30 min on 4 consecutive days. Fixed under pentobarbital anaesthesia (30 mg/kg) by intratracheal instillation of 2.5 % glutaraldehyde in 0.1 M sodium cacodylate buffer (pH 7.4) before opening the thorax. Postfixation with 1 % osmium tetroxide in sodium cacodylate buffer. Embedded in Epon 812 and sectioned at 50 nm. Lead citrate and uranyl acetate. Plate 4050...

Sato, Abe, and Singawara reported that at 35-40°C di and trimethylol-melamines hydrolyze under acidic conditions (pH 1-5). At pH 3.5 the rate of hydrolysis passes through a maximum. 

The chemistry of melamines and phenoHcs is quite similar. In both cases formaldehyde [50-00-0] is added to the reactive sites on the patent ring to form methylol phenols (3) or methylol melamines (4) (see Phenolresins Aminoresins). There ate six reactive sites on the triazine ring of melamine [108-78-1] (1) so it is possible to form hexamethylolmelamine. However, the most common degree of methylolation is 1.5—2.0. The ortho and para positions of phenol ate active thus phenol can be trimethylolated (2). However, as with melamine, lower degrees of methylolation such as 1.2—2.5 ate... 

The first method is based on the melamine reaction with formaldehyde and the resulting trimethylol derivative is reacted with diethanolamine [10] (reactions 15.37 and 15.38). 

The natural abundance 15NNMR spectra of urea-formaldehyde and melamine-formaldehyde adducts and resins (recorded with approximately 20000 pulses) can be used for direct determination of different types of amino groups. The spectra of a urea-formaldehyde resin (1 1 formaldehyde/urea ratio) after 15 and 60 min of reaction are shown in Fig. 3. On the basis of chemical shifts of urea based model compounds (monomethylol-, Af,AT-dimethylol- and N,N,N -trimethylol-ureas) the following assignment of nine 15N resonances is proposed... 

Amoco HS-7 is a soya fatty acid, trimethylol propane, neopentyl glycol, isophthalic acid alkyd of acid value 6. The formulation is available from Amoco Chemicals (publication GTSR-75B). Cymel303 is a hexamethoxy methyl melamine resin at 100% solids supplied by Cytec. 

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