Surface Modification Of Biaxially Oriented Polypropylene Films And Its Abrasion Resistance

For improving the abrasion resistance of BOPP, a new method of surface modificationcoating is proposed: through the sol-gel process using a silane coupling agent, Aluminumtri-sec-butoxide and tetraethoxysilane as the precursor, P-toluene sulfonic acid as the catalyst,and moisture in the air for hydrolysis. In order to develop the interfacial interaction between thehighly crosslinked coating and polypropylene films, the chemical oxidation that KMnO4/H2SO4solution is chosen for surface treatment agent, is taken to modify the surface of BOPP films.Using the prepared surface treatment agent to modify BOPP films, the effects of surfacetreatment agent to the transmittance, surface free energy and mechanical properties of BOPPfilms are investigated. On this basis, we prepared KMnO4-treated functionalized biaxiallyoriented polypropylene (BOPP) films coated with a hybrid material, and confirmed the abrasionresistance.The nanoparticles were relatively uniformly dispersed, and the average size of nanoparticlesis30nm by the method of sol-gel. When the Al2O3sol is added to the SiO2sol, the Si-O-Algroups are formed. The coatings containing Al2O3sol were all transparent, which suggests thatcoating with the Al2O3sol produces films with high transmittance.According to the research on the modification condition of surface treatment agent, resultsshow that functional oxygen-containing groups are grafted on the surface of BOPP film toimprove interfacial adhesion, which also improve the surface free energy by28.1%. What ismore, KMnO4oxidation treatment does not have effect on the transmittance and mechanicalproperties of BOPP films, making easily applied in industry. It provides a new option to thesurface modification of BOPP films.On the basis of above studies, KMnO4-treated functionalized biaxially orientedpolypropylene (BOPP) films coated with a hybrid material are synthesized by the method ofdip-coating, and the abrasion resistance and mechanical properties of the resultant films areexamined. The results show that compared with raw sample, the sample coated with sol(TEOS/ASB=15:9) exhibits the best abrasion resistance, which is improved by79.51%. And mechanical properties of sample coated with sol (TEOS/ASB=15:3) are improved by132.24%,respectively. According to the data in the NIST X-ray Photoelectron Spectroscopy database, Al,O and Si elements are confirmed. The spectra obtained indicate that Al and Si elements in thefilms mainly exist as Al3+and SiO2, respectively. Various covalent bonds improved interfacialinteractions between the highly crosslinked coating and the polypropylene films. In conclusion,modified BOPP films with good mechanical properties and well abrasion resistance aresynthesized by coating with the sol (TEOS/ASB=15:9).