1. Factors affecting the preservation of cosmetics and […]
1. Factors affecting the preservation of cosmetics and related tests
Undoubtedly, the primary function of cosmetic packaging is the protection of the contents. The ingredients of cosmetics are added with substances required for the growth and reproduction of microorganisms, such as glycerin, protein, etc., and when the cosmetics are contaminated by microorganisms, they become odorous, deteriorated and moldy, the quality of the products decreases, and moisture and oxygen are factors that affect the growth of microorganisms. . Most cosmetics contain oils and fats. The unsaturated bonds in the oil are easily oxidized to cause deterioration (rancidity), and this oxidation is a chain reaction. As long as a small part begins to oxidize, it will cause complete deterioration of the oil and at the same time Peroxide, acid, aldehyde and other substances that are irritating to the skin and give off rancid odor. Oxygen is the most important external cause of rancidity. Without the presence of oxygen, it will not cause oxidation and cause rancidity. The increase of water will also cause hydrolysis of oil and fat and accelerate the automatic oxidation reaction. Moreover, water will provide living environment for microorganisms and reduce The vitality of certain antioxidants. The preservation of aromatic gas is the focus of cosmetic packaging. For some cosmetics, the aromatic gas itself is the real "product". If the aromatic gas is lost, the "product" that is actually sold disappears. Therefore, for cosmetics, it is extremely important to prevent the loss of odor.
It can be seen that anti-corrosion, anti-oxidation and prevention of odor loss are the key points of cosmetic preservation. It is necessary to carry out the following tests on cosmetic packaging: the speed of gas permeation of packaging materials, the gas content inside the packaging, and whether the packaging is intact, that is, the barrier property of packaging materials, packaging The analysis of the headspace inside the object and the tightness of the package.
Barrier refers to the barrier effect of packaging materials on the penetration of gas, liquid and other permeate through the material. Its advantages and disadvantages can directly affect the quality of the product during the shelf life, and it is also an important indicator to assess the shelf life of the product. The barrier properties of the package are one of the important testing items for cosmetic packaging, including oxygen permeability, moisture permeability and organic gas transmission rate.
The tightness of the package mainly refers to whether there is a leak point in the package. Leakage is the probability that gas leaks through the cracks, micropores or small gaps between the two materials or into the package. The probability of leakage in the heat-sealed parts of the package and the mouth of the container is high. To solve this problem, Strict production processes are required and the process is adjusted in time based on the test data. Commonly used detection methods are positive pressure method and negative pressure method. Among them, the application of the positive pressure method should be especially valued, because the detection method can not only detect the sealing of common packages, but also expand the inspection object with accessories.
Cosmetics have a good visual aesthetic and are beautifully printed, which is more important for the detection of their printing quality. At present, the conventional items for quality inspection of cosmetic packaging printing are the abrasion resistance (scratch resistance) of the printing ink layer, the ink adhesion fastness detection, and the color discrimination. Among them, ink adhesion fastness detection and color discrimination have clear detection methods, but it is necessary to pay attention to the wear resistance test. At present, the standard test method requires the load block to adopt linear motion, but the international standard requires the load block to adopt curve motion. form.