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The booming milk tea industry has not only promoted the diversification of beverage flavors, but also put forward higher requirements for packaging materials. The sealing film of the milk tea cup lid, as a key link between beverages and consumers, has a direct impact on the hygiene, taste and consumer experience of the beverage. Transparent EVOH sealing film has gradually emerged in the market with its excellent barrier properties, weather resistance and environmental protection characteristics.
EVOH (ethylene-vinyl alcohol copolymer) is known for its excellent barrier properties, but this property also brings specific application challenges. In the milk tea industry, beverages may experience a variety of temperature changes from refrigeration to room temperature and even high temperature, and humidity fluctuations cannot be ignored. High temperature may cause EVOH material to soften and reduce its mechanical strength, thereby affecting the sealing effect of the sealing film; while low temperature may make EVOH brittle and easy to crack, which will also affect the sealing performance.
Excessive humidity may cause the surface of the transparent evoh sealing film to absorb water, affecting its adhesion and sealing performance. Humidity changes may also cause changes in the internal stress of the material, causing the sealing film to deform or crack.
In response to these challenges, the industry has explored a variety of solutions. First, by adjusting the formula of EVOH materials, such as changing the proportion of copolymers, adding plasticizers or antioxidants, etc., to improve its temperature and humidity resistance. At the same time, select adhesives with excellent adhesion to ensure a close fit between the sealing film and the cup lid. Secondly, use advanced processing technologies such as multi-layer co-extrusion and stretch blow molding to optimize the microstructure and properties of the sealing film, improve the uniformity of the material, and improve the mechanical strength and sealing performance. In addition, it is also possible to design a sealing film structure with adaptability, such as adding shape memory materials to enable it to maintain good sealing performance at different temperatures, or using an adjustable sealing pressure design to adapt to the sealing requirements under different humidity conditions.
In order to ensure the stability and reliability of the sealing film, it is crucial to establish a sound quality control system. This includes rigorous performance testing of the sealing film, such as sealing tests under different temperature and humidity conditions, tensile strength tests, tear strength tests, etc. Through feedback from test data, the material formulation and processing technology are continuously optimized to improve the performance of the sealing film.
