Theoretical And Experimental Research Of The Heat-Sealing Parameters Impacts On The Heat-Sealing Strength Of Black-and-White Film For Milk Packaging

The milk is popular with the consumer, and the heat-sealing technique plays an important role as the final procedure of milk-packaging. The quality of the packaging would be improved if the best parameter of the heat-sealing techniques were determined.This paper aims at analyzing effective factors of the black-and-white film for milk packaging, and establishes the reasonable mathematical model. The optimum heat-sealing parameter values were obtained by using theoretical calculation and experimental analysis. The results showed that the mathematic model on the heat-sealing properties of plastic film was effective.Firstly, heat-sealing principle of the polyethylene heat-sealing film was analyzed, and a series of heat-sealing experiments were performed on the black-and-white film. Multiple single-factor experiments and uniform design experiments compose the chief part of experiment. The single-factor experiments were used to analyze how single experiment parameter variation affects the heat-sealing properties. The single-factor experiments confirm an effectual range of heat-sealing parameters for uniform design experiments.Secondly, in order to find the best heat-sealing parameters, experiments using uniform design method were arranged, which used quadratic polynomial regression analysis. The paper established an equation of the heat-sealing strength about the temperature, time and pressure, and an equation of the hot tack about the temperature, time, pressure and cooling time was established, too. The best production parameter for heat-sealing strength and hot tack were obtained through analysis of the equation. In order to verify the equation, the experiments were carried through by the equational data, and the experimental data was close to the equational data. Influence of heat-sealing parameter on heat-sealing properties was close to the result ofsingle-factor equation, which proved that the equation can be used for production and provide the theory reference for pratical application.As the black-and-white film for milk packaging is produced by using coextrusion blow molding machine, the film of machine direction is shrinkable when the film is sealing. In order to find out influence of shrinkable properties on heat-sealing properties, the experiments of temperature shrinkage and time shrinkage were carried through. The results proved shrinkable properties of the black-and-white film for milk packaging might reduce the heat-sealing strength of the black-and-white film for milk packaging. So, shrinkable properties of the film should be considered carefully when heat-sealing parameters are determined.