Study On Preparation And Properties Of Laminating Product Based On PVA Film

Laminating is a common technology of post-print surface processing.The frequently-used plastic film is BOPP or BOPET,which can't be degraded,resulting in the high cost of reuse and recycle after the waste of the laminating products,thus losing commercial value.The paper chooses water-soluble polyvinyl alcohol?PVA?film as the coating material to replace the existing materials.In the recovery process of the waste laminating products,paper-plastic separation is not required and the plastic can dissolve with paper in water to form pulp.It can effectively reduce the cost of recovery;improve the reuse rate of laminating materials and save resources.In this paper,two kinds of laminating products are prepared.One is the PVA-EVA pre-coated laminating product,which chooses the pre-coating technology.The PVA film soluble in water at room temperature and the hot-melt adhesive of ethylene-vinyl acetate?EVA?are used as the laminating materials.The other is the PVA-starch sensitibvity laminating product,which chooses the sensitibvity membrane technology.The PVA film soluble in water at high temperature and the starch adhesive are used as the laminating materials.Prepare the modified oxidized starch adhesive with natural polymer starch.The properties of two kinds of laminating products were tested and analyzed respectively.The results show that:1.The properties of PVA films soluble in water at room temperature were tested according to the national standard GB/T 27934.1-2011.The surface tension was38dyn/cm²;haze was 10%;tensile strength was 70MPa and the heat yield was?1%in both the longitudinal and transverse directions,meeting the requirements of pre-coated laminating film substrate.In order to increase the adhesion between EVA and PVA film,the surface tension of PVA film treated by corona method was up to 42dyn/cm².2.Based on the orthogonal design test method,taking the peel strength of the laminating products as the evaluation index,selecting temperature,pressure and speed as the three influencing factors to design the L₉?3³?orthogonal test.The optimum process parameters of PVA-EVA pre-coated laminating were obtained as follows:laminating temperature 80?,pressure 10MPa/cm²,speed 9m/min.The average peel strength of the laminating product in verification test was about 4.25N/cm.The appearance of the laminating product was good,with smooth surface,good transparency,no foaming film crimp,small shrinkage,high stability,small color difference.The PVA film can dissolve in water,but the EVA hot melt adhesive can't completely dissolve in water.3.According to GB/T 27934.1-2011,the correlation properties of PVA film soluble in water at high temperature were measured,with the thickness of 20?m;the surface tension of 42dyn/cm²,haze of 1.27%and the tensile strength of 135MPa.The thermal yield was less than 1%in longitudinal and transverse direction,which meets the requirement of film material of sensitibvity membrane.4.Based on the single factor experiment of mass fraction of starch,oxidant,sodium hydroxide and stabilizer,the L₉?3⁴?orthogonal test for preparing oxidized starch binder was designed,and the optimum formula and proportion of starch binder were obtained.The mass fraction of starch,oxidant and sodium hydroxide were 30%,12%and 8%respectively.The stabilizer was PVP,and the verification test was carried out,with the solid content of starch binder of 29.1%.The average peel strength was 1.98N/cm,and the properties of the coating were good.The PVA film and starch adhesive could be completely dissolved in water.