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Epoxy Acrylate Resins and Vinyl Hydroxy Esters |
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Written by Renato Rindone
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Monday, 14 September 2009 12:42 |
Improved Reaction Conditions for Epoxy Resin Acrylate Ester Formation. 
A better way to Vinyl Hydroxy Esters using Hycat™ Catalysts.
Literature is replete with references on how to prepare epoxy acrylates and epoxy methacrylates.
The reaction of a saturated carboxylic acid with an epoxide is also well known and many different catalysts to accelerate this reaction is also shown in literature and practiced in the industry. But the current catalysts used for the saturated carboxylic acid reaction don’t always work that well when making the acrylate/vinyl ester. For example, when using a trialkyl amine base or an imidazole, usually at an elevated temperature, it is difficult to prevent some polymerization of the acrylate to form the poly-acrylates or homo-polymerization to form the ether. Furthermore, typically with amine catalysts, the conversions generally stop or it significantly slows down after 75-85% conversion due to the formation of an adduct of the hydroxyl group hydrogen and the nitrogen amine. Also, elevated reaction temperature (e.g., 75 to 100 OC) conditions are necessary to achieve these conversions.
Because of the highly active nature of the Hycat™ catalysts and especially Hycat™ 2000S and Hycat™ OA, these synthesis issues are eliminated or significantly reduced. Using the Hycat™ catalysts conversion of over 90% of the predominantly β-hydroxy ester is realized with little or no homopolymerization. As with the amine or imidazole type catalysts, a radical scavenger, like hydroquinone, is still needed to prevent the polymerization of the acrylate group but because the reaction can be conducted at a lower temperature, e.g., 25 to 60 OC, this side-reaction is significantly minimized
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