Dehydration, unsaturated polyester

Chlorendic Acid. Chlorendic acid [115-28-6] and its anhydride [115-27-5] are widely used flame retardants. Chlorendic acid is synthesized by a Diels-Alder reaction of maleic anhydride and hexachlorocyclopentadiene (see CyclopentadlENE and dicyclopentadiente) in toluene followed by hydrolysis of the anhydride using aqueous base (60). The anhydride can be isolated directly from the reaction mixture or can be prepared in a very pure form by dehydration of the acid. The principal use of chlorendic anhydride and chlorendic acid has been in the manufacture of unsaturated polyester resins. Because the esterification rate of chlorendic anhydride is similar to that of phthalic anhydride, it can be used in place of phthalic anhydride in commercial polyester... 

Breakdown of diethylene glycol use is as follows unsaturated polyester resins (20%), polyester polyols (15%), antifreeze blending (12%), triethylene and tetraethylene glycol (9%), solvents (9%) morpholine (7%), and natural gas dehydration (4%). Much of the market is captive. The merchant market is small. 

Maleic anhydride (2,5-furandione) is obtained as a by-product in the production of phthalic anhydride and by the vapor phase oxidation of butylene or crotonaldehyde. It is also obtained by the dehydration of maleic acid and by the oxidation of benzene. Maleic anhydride is used for the production of unsaturated polyester resin. This reactant, like most reactants, is fairly toxic and should be treated as such. 

Diethylene glycol is used in the manufacture of polyurethane resins, unsaturated polyester resins, antifreeze blending, triethylene glycol, morpholine, and natural gas dehydration. 

Diethylene glycol usage is about 800 million lb/year in the United States. Major uses are unsaturated polyester resins (21%), polyurethane resins (21%), and antifreeze blending (10%). Other applications include use as raw materials for triethylene glycol (7%) and for morpholine (7%). Diethylene glycol is also used for dehydration of natural gas and in textile conditioning. 

Use Production of polyurethane and unsaturated polyester resins, triethylene glycol textile softener petroleum solvent extraction dehydration of natural gas, plasticizers, and surfactants solvent for nitrocellulose and many dyes and oils humectant for tobacco, casein, synthetic sponges, paper products cork compositions, bookbinding adhesives, dyeing assistant, cosmetics, antifreeze solutions. 

ATH is an inorganic FR widely used because of its low cost and nontoxicity and easy to incorporate into various thermoplastics and thermosets. It decomposes 180 and 200 °C (12.1). However, it is very difficult to dehydrate it completely. It is generally used in plastic formulations with processing temperamres around 190 °C, such as polyolefins for electric cables, PVC, PU, EVA, thermosets such as unsaturated polyesters, phenolics, epoxy, and rubber. 

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