Tightness test is a very important test item among many test items for cosmetic packaging materials. Packaging materials that fail the tightness test have the risk of material leakage or that the material body will become less or dry as the product storage time increases. There are many types of cosmetic packaging materials, and there are relatively few standard methods for testing the sealing properties of packaging materials. It can be said that most cosmetic factories carry out packaging material tightness tests in accordance with their own internal control standards, with different methods and standards.
At present, there are five main methods for testing the tightness of cosmetic packaging materials:
1. Squeeze test method;
2. Side (upside down) test method;
3. Vacuum test method;
4. Negative pressure air tightness test method;
5. Positive (plus) pressure air tightness test method.
For packaging materials that are easily deformed, such as PE hoses, the extrusion method can be used to test the sealing properties of the packaging materials. For example, the tightness of the PE hose and the cover can be screwed on and squeeze the hose body properly. If the hose is always in a flatulence state and does not leak, it can be judged that the tightness of the hose is qualified. If the hose makes a sound of air leakage and the tube body becomes deflated, the hose's tightness is unqualified.
If squeezing the hose cannot determine whether the hose is leaking, you can immerse the cap end of the hose in the water and squeeze the tube body to see if there are any bubbles coming out. Out, it means that the tightness of the hose is unqualified. In addition, for the aluminum-plastic composite bag mask that has been filled and heat-sealed, the extrusion method is usually used to check whether the heat-sealed area is not properly sealed.
By squeezing the mask bag to see if there is material overflow at the opening of the heat seal to judge whether the heat seal of the mask bag is qualified. This method is convenient and quick, but different people have different squeezing strength and methods. There is no quantitative standard, which is a major defect of this method.
The side (upside down) test method is mainly suitable for packaging materials with large openings such as cream bottles. Airless bottles are usually also tested for tightness using this method. The aforementioned packaging materials will basically fail the tightness test if the vacuum test is used. Although the packaging materials of cream bottles have large openings, the materials are generally thick, and there is usually no so-called leakage.
However, if the sealing is not good, the product will become less or dry after a long time. problem. The side (upside-down) test method is to fill the packaging material to be tested with about the actual filling amount of water (the water with pigment can also be added to make it easier to find which packaging material is leaking), and an electronic balance with a division value of 0.01g is used. The bottles are weighed and labeled, and placed on the side for 24h (the editor uses side placement and the test time is 24h, but according to the actual situation, usually not so long). After the time is up, each bottle is weighed again. If the reduction exceeds 0.02g, it means Leaking.
Bottles that have obviously leaked water can be seen directly. Weighing is used. One is to avoid that if there is a leaking bottle of water when placed on the side, it is not known which bottle is leaking. You can know the severity of the leak. Of course, use paper under the bottle or other methods to check whether there is water leakage, but weighing is the most reliable way.