Design And Performance Study On The Black & White Film For Milk Packaging

Based on the decision of the structure of the black and white film and theproportion span of raw material, adopted uniform design method to design theexperiment program, the film is manufactured with the tri-co-extrusion machine andits performances are analyzed such as black and white uniform, tension intensity, heatsealing, friction coefficient, permeability and so on.The performance of the film is researched in detailed on some testing equipment,such as universal testing machine, penetrating gas apparatus, penetrating moistureapparatus. The aim of the paper is to offer an instructed design method of the film.The structure design of the film is the three layers, in which the materialcomposition is PE+ white matrix/ PE+ white matrix/ PE+ black matrix. The outerlayer, also called printing layer, is white and acts as the role of inhibiting luminousbeam and moisture. The middle white layer masks the inner black and inhibitsmoisture. The inner layer is black and acts as light barrier and heat sealing.The experiments are arranged on the base of uniform design method. Taked thepercentage of LLDPE in the each layer of the film as three factors, the span of theLLDPE percentage is from 30% to 80% . For each factor there are six levels. Research suggests that light barrier is acquired effectively when thepercentage of the white matrix in the outer layer and the middle layer is larger than orequal to that of the inner layer. The percentage of LLDPE is the major effected factoron mechanics performance of the film and a regression equation can be achieved byregression analysis.In the condition of 118 ℃ and 0.25MPa, the sealing intensity mostlyapproximates to 1.4mPa. The friction coefficient of the film is within the permissionof the auto-packaging machine. The O2 permeability is reduced with the addedpercentage of LLDPE in the layer, however, proper quantities of black matrix addedin the film can also decrease the O2 permeability. This is relevant with interfacediffusion because the black layer reduced the effect of light sensation.PE is an excellent material of barrier moisture, and when a small amount ofmatrix is added in the film, there is little impact on the performance of barriermoisture.