Abstract: A method to test the opening force for cover film sealed yogurt plastic cups was put forward by quantifying the opening force using special force testing equipment to completely simulate human-machine operations, which is mainly characterized by the initial opening force and the continuous opening force. Commercial yoghurt packagings consisting of different combinations of two plastic cups made from polypropylene (PP) and polystyrene (PS) with aluminum foil composite film, aluminizer composite film and embossing aluminum sheet were tested using the method in this study, and the ranges of opening force for them were obtained. The results showed that the initial opening force was significantly greater than the continuous opening force; the initial opening force for PS and PP cups was 10–25 N, and the continuous opening force was more than 10 N for the cups sealed with embossing aluminum sheet, whereas for the cups sealed with aluminumplastic composite film it was only 4–8 N. For cups sealed with the same films, the opening force for PS cups was higher than for PP cups. Moreover, the initial opening force for cups sealed with aluminizer composite film was greater than for those made from the same material and sealed with the two other films, and the continuous opening force was significantly increased for cups sealed with embossing aluminum sheet compared with those sealed with the other films. There was a significantly smaller difference between the initial and the continuous opening force for embossing aluminum sheet, and the sealing intensity from it was more stable.

Key words: sealing film cover for plastic cup; initial opening force; continuous opening force; testing method

摘要： 研究检测酸乳塑杯封口盖膜揭开力的测试方法,利用专门的力值检测设备完全模拟人机操作对酸乳塑杯盖膜揭开力进行量化,主要表征为初始揭开力和持续揭开力.并以聚丙烯(polypropylene,PP)和聚苯乙烯(polystyrene,PS)2种塑杯,铝箔复合膜、镀铝复合膜、压花铝片3种封口盖膜组合的市售酸乳包装为实验对象,通过该测试方法进行塑杯包装封口盖膜揭开力测试,最终得到不同包装形式相应的盖膜揭开力力值范围.结果表明:塑杯封口盖膜的初始揭开力明显大于持续揭开力,PS、PP塑杯封口盖膜初始揭开力值为10～25 N;以压花铝片为封口材料时,塑杯封口盖膜的持续揭开力大于10N,以铝塑复合膜为封口材料时,塑杯封口膜的持续揭开力仅为4～8N;同种封口盖膜,PS塑杯的盖膜揭开力大于PP塑杯.而同种塑杯,镀铝封口膜的初始揭开力高于压花铝片和铝箔封口膜,压花铝片的持续揭开力高于镀铝封口膜和铝箔封口膜,差距悬殊.且以压花铝片为封杯材料时,盖膜初始揭开力与持续揭开力的差值会明显小,封杯强度相对稳定.

关键词: 塑杯封口盖膜；初始揭开力；持续揭开力；测试方法