Dibenzylidene Sorbitol (DBS) and Di(P-methylbenzylidene) Sorbitol (P-MeDBS) derivatives, used as crystallinity Polyolefine kind resin transparency nucleating agent, can reduce to a large extent the product's haze, improve its transparency, validly resin's rigidity, heat resistant temperature and modulus of bending. Its good transparency and glossiness are as good as transparent material. It has become polyolefine processing auxiliary that develop most quickly and consume most massively in the world. It is used widely in the processing of transparent plastic package vessel, equipment's parts, file folder and transperene material. The nucleating agent of DBS analog is made from one mole Sorbitol and two mole benzaldehyde dehydration condensation reaction, which associates with by-reaction. Sorbitol containing six hydroxyl group ring condensates with benzaldehyde and yield three acetal compounds-monobenzylidene Sorbitol(hereafier briefly referred to as "MBS”), DBS and Tridibenzylidene Sorbitol(hereafter briefly referred to as "TBS”). MBS and TBS are by-products. The experiment is carried out under the condition of temperature 75'C, reaction time 4 hours and agitation velocity 370 r/min. We conducted intensive research on the effects of Sorbitol/benzaldehyde(S/B) and Sorbitol/P-Me-DBS feeding molar ratios. When B/S is 2, the target product's yield can even be improved to 98.5% and 97.17% respectively, whereas feeding molar ratio are increased or reduced, the product's yield reduces definitely. The reason is that DBS and Derivative are produced by the process that one mole Sorbitol and two mole benzaldehyde condense. Sorbitol can't react validly with the molar ratio being lower than 2 .While B/S is in excess of 2.1, the excess benzaldehyde condenses some yielded DBS and produces TBS. Research data show that feeding molar ratio ought to range from 1.9 to 2.1 in order to acquire high yield and selectivity's target product. The result of synthesizing P-Me-DBS homologue's molar ratio change can verify this.
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