二氧化硅开口剂在LLDPE薄膜中的应用及开口机理

Application and Opening Mechanism of Silica Opening Agent in LLDPE Film

开口剂用于塑料薄膜的生产,可有效改善薄膜的开口性能。文章使用沉淀法合成四种二氧化硅(SiO_(2))开口剂,在相同的加工条件下分别与线型低密度聚乙烯(LLDPE)熔融共混制备四种LLDPE/SiO_(2)母粒并吹塑成膜。结果表明:四种开口剂都能满足LLDPE膜的防黏开口性能要求,动/静摩擦系数均降到0.11以内(属于高爽滑性)。50℃、7 kPa负载下压制24 h后,四种LLDPE/SiO_(2)膜间均没有任何粘连,而纯LLDPE膜有一定的粘连。AFM测试表明,亚微米级SiO_(2)开口剂粒子附近都存在微型凹坑,这些凹坑对降低负压、减小范德华力从而降低LLDPE/SiO_(2)薄膜的粘连起关键作用。根据实验数据提出一种适用于LLDPE膜的开口防粘连的模型,该模型有望用于指导生产防黏开口效率更高的开口剂。

Opening agent is used in the production of plastic films,which can effectively improve the opening properties of the film.In this paper,four kinds of silica(SiO_(2))opening agents were synthesized by precipitation method,and four kinds of LLDPE/SiO_(2) masterbatch were prepared by melt blending with linear low density polyethylene(LLDPE)under the same processing conditions.The results show that the four kinds of opening agents can meet the requirements of anti-sticking and opening performance of LLDPE film,and the dynamic/static friction coefficients are all reduced to less than 0.11(belonging to high smoothness).After compacting at 50℃and 7 kPa for 24 h,there was no adhesion between the four LLDPE/SiO_(2) films,but pure LLDPE films had some adhesion.AFM test shows that there are micro pits near the submicron SiO_(2) opening agent particles,which play a key role in reducing negative pressure and van der Waals force,thus reducing the adhesion of LLDPE/SiO_(2) films.Based on the test data,a model of anti-sticking opening for LLDPE film is proposed,which is expected to be used to guide the production of opening agents with higher anti-sticking opening efficiency.