Insertion of propylene oxide into methyl esters is accomplished using a proprietary alkoxylation catalyst. The alkoxylation mechanism is believed to involve transesterification between the alkoxylated metal-alkoxide of the catalyst and the ester. Optimal alkoxylation conditions are discussed. The effect of inserting propylene oxide prior to ethoxylation on surface properties and foam performance is examined. JSD 1, 167-175 (1998). KEY WORDS:Fatty methyl ester propoxylates, methyl ester propoxylates, performance, physical properties, propoxylated methyl esters.Annually, approximately 500 million pounds of various propoxylates (excluding those used for making polyurethanes) are used worldwide today (1). Most of this volume is made up of various ethylene oxide (EO)/propylene oxide (PO) block copolymers. The majority of the remaining volume consists of various alcohol ethoxylates which have been "capped" by adding PO to the end of the molecule.The utility of PO lies in the ability of the propoxy group to reduce foaming. These groups are branched, which sterically hinders the capacity of the surfactant to pack at the interface.Until recently, the application of PO (and other alkylene oxides) has been restricted to molecules having an active terminal hydrogen, such as alcohols, alcohol ethoxylates, polyethylene glycols, etc. New alkoxylation catalysts, however, have been developed which effectively insert alkylene oxide into esters between the ester carbonyl and the alkoxy group. These catalysts are described elsewhere (2-9).The purpose of this paper is to detail studies examining the ability of a unique alkoxylation catalyst to insert PO into methyl esters, and the impact of PO on the performance of methyl ester alkoxylates. EXPERIMENTAL PROCEDURESPropoxylation of methyl esters. The alkoxylation catalyst (NOVEL® II) consists of a calcium and aluminum complex partially neutralized in an alcohol ethoxylate base (8). Alkoxylations were performed in conventional alkoxylation equipment using 2.67% catalyst (based on the final weight of the catalyst in the product-batch size 150 g). The alkoxylations were performed in a 600-mL stainless steel autoclave equipped with a magnetic stir bar, an internal cooling line, and thermocouples. The autoclave was placed into a heating block which was controlled using an I 2 R therm-o-watch model TCP3-1200 controller (I 2 R, Inc., Chaltenham, PA). The cooling line in the autoclave was hooked up to either water or air for cooling. Air or water cooling lines were controlled using a therm-o-watch model L9-1500 RTD controller (I 2 R, Inc.). A cooling line was opened or closed, dependent on temperature readings from the autoclave thermocouple. A 500-mL bomb containing the alkylene oxide under 50 pounds (23 kg) of N 2 pressure was connected in parallel with a graduated site-glass and connected to the autoclave via stainless steel tubing.The basic alkoxylation procedure can be broken down into five major steps: (i) charging the EO reservoir, (ii) charging the methyl ester, (iii) removal of moistu...
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