| 摘要 |
The present invention describes a method for obtaining compounds of the general formula below mentioned, where p, q, m and N can be modified upon ranging the amount of glycol and unsaturated anhydride and using a process consisting in a glycolysis stage, followed by an sterification stage for obtaining unsaturated polyesters, which can be photocured by the sun light without requiring the addition of unsaturated copolymers such as styrenic acrylics. The glycolysis stage consists in the trans-sterification of the polyesters such as polyethylene terephthalate (PET) with alcohols having from about 6 to about 20 carbon atoms, or a mixture thereof, containing alkylaryl groups or straight, branched or cyclic aralkyl groups (i.e., 1,8-octanodiol, triethylenglycol, propylene glycol, pentaerythritol, bisphenol-A), in the presence of a combination of tin, sodium and potassium catalysts at a temperature ranging from about 150¦C to about 250¦C in a solvent suitable for entraining the ethylenglycol released therefrom. Said process preferably uses a waste PET, although the method may be applied to any PET. The process differs from the patented processes US5121064 and US5319128 as follows: the nature of the catalyst, the ethylenglycol carrier and the combination of: catalyst/ethylenglycol carrier/reactor volume, for improving the efficacy and time of the trans-sterification reaction. The second stage of the process consists in the use of diesters or anhydrides or unsaturated acids (i.e., maleic anhydride, fumaric acid, itaconic acid and chloride-maleic acid), in the presence of a combination of tin, sodium and potassium catalysts at a temperature ranging from about 150¦C to about 250¦C, but preferably ranging from about 120¦C to about 180¦C, in a solvent suitable for entraining the water generated therefrom. The process differs from the patented processes US6,512,046, US 6,127,436 in that the unsaturated polyester does not require to be mixed together with acrylate or styrene pol ymers or copolymers so as to be fhotocurable and/or obtain resistant and flexible products.
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