IMPROVING THE PERFORMANCE OF PAPER STRAPS BY PVOH/PAA COATING

Abstract

Oval international is trying to completely replace Conventional plastic and material straps from paper straps. But some environmental conditions like tropical regions where humidity is high and tackiness of straps is major concern is still needed to be addressed. Also acid rain in south American regions is also a hurdle in performance of paper straps. So paper straps with moisture resistant and pH responsive behavior i.e. paper straps shows resistant in acid rain conditions but in repulper where pH is slightly basic they get easily disintegrated. For this problem literature shows two type of solutions. One is crosslinking of existing PVA with PAA and second one is to coat pva with solutions of CAP as it is coated in enteric coating. This work focuses on first one. PVA crosslinked with PAA offers significant water and moisture resistant as well as ph responsive behavior. This work includes film preparation of desired coating composition followed by testing of films to show water resistance and solubility in different type of conditions i.e in water having different Ph. Also films were cured at different temperature to impart strength and water resistance in them. After that composition is selected based upon the solubility results. Composition 99%DOH PVA and 90/10 PVA/PAA ratio was found to be more suitable so it was coated on paper straps and straps were also cured at different temperature. After that these straps were testes for tackiness and repulpability. At the end it was found that PVA/PAA 90/10 DOH99% cured at 120 c was most suitable with comparable tackiness and good repulpability results.