Definition of Compatibility Testing
The compatibility of cosmetic and its bulk refers to the interaction between plastic packaging and cosmetics in a broad sense, including chemical compatibility, physical compatibility, and biocompatibility.
The following is a brief description of the specific situations of each type of incompatibility:
1. Chemical incompatibility:
The chemical components of the packaging materials, the decomposition products during processing, chemically react with the cosmetic ingredients, and have adverse effects on the cosmetics or packaging materials; chemical incompatibility is manifested in changes in the appearance and smell of the packaging materials or cosmetics. For example:
Bulk turns yellow:
Packaging material turns yellow:
2. Bioincompatible:
Certain substances in the packaging material migrate into the cosmetics, causing adverse effects on users; the release of harmful substances exceeds the measurement specified in the relevant cosmetic hygiene standards or specifications of the country where the cosmetics are sold; generally, harmful substances include various Plastic additives, residual solvents, volatile organic compounds, harmful metal elements, etc. Of course, not all dissolved plastic additives will have a serious impact on the properties of cosmetics. When the dissolved component is one of the cosmetic ingredients, the dissolved amount is small, and the dissolved substance is harmless to the user, this phenomenon is normal. compatible. For example:
The colorant in the plastic leached into the bulk (the bulk were originally beige)
3. Physical incompatibility:
Due to the influence of each other, the packaging material and the bulk have undergone physical changes; physical incompatibility phenomena are manifested as penetration, adsorption, cracks, cracks, and dissolution. In the test judgment, physical incompatibility is often misjudged as chemical incompatibility, because the phenomenon of physical incompatibility is more obvious and the reaction is more violent. For example:
surface crack:
stress cracking:
In view of the fact that the plastics used in cosmetic packaging materials have certain solvent resistance and the cosmetics themselves are relatively mild, the incompatibility between cosmetics and packaging materials is more manifested as physical incompatibility. In addition, it has been proved by fine chemical quantitative analysis experiments that the incompatibility between cosmetic packaging materials and their bulk usually does not appear in a single form.
About Compatibility Test Results
The expression form of the results of the compatibility test is actually quite complicated. I usually encounter many colleagues who ask, since the compatibility is unqualified, then all the samples should have reacted with the bulk, and each sample should have the question is right, why are there good and bad samples at the same temperature? In fact, there is a certain ratio of unqualified compatibility. For example, when 10 samples were tested at 40°C, only 2 samples were cracked, and the remaining 8 samples were intact. But when you expand the sample size to hundreds of samples, it will be found that the number of cracked samples has expanded to dozens; by analogy, if such packaging materials are put into mass production, the final problems will not be a small number.
Compatibility accident case
Case 1
A century-old luxury goods company added sunscreen ingredients to a base makeup product developed in the early stage. Since most of the plastic containers at that time were made of PET, they didn't think much about it and still used the same material. The company's testing mechanism is not perfect, and after a period of time, they were shocked to find that the bottle was cracked! After research, it was found that the sunscreen ingredients in the bulk were physically incompatible with the PET container, and the company quickly updated the product; since then, the company has spread word of mouth that products with sunscreen ingredients are strictly prohibited from using PET packaging materials! Of course, this sentence is not completely accurate due to the influence of the technical level of the time. Now, the common practice is to use PP or copolyester (such as PCTA) materials with more suitable properties for sunscreen products.
Case 2
A world cosmetics giant, a liquid foundation product, because the original packaging material is used, and the bulk only change the color, so the compatibility test can be exempted after the evaluation. After the product is launched, the normal temperature stability test of the quality department It is reported that the color of the liquid foundation appears on the inner wall of the packaging material, which is flaky and fused with the inner wall of the plastic. After washing with water and solvents, there is no way to clean it. It turns out that the pigment of the liquid foundation is absorbed by the packaging material. This case also fully proves the inescapability of compatibility testing.
Conditions for compatibility testing:
Take the compatibility test plan of a giant in the cosmetics industry as an example:
(The following test conditions can be selected according to different situations of the product)
⦁ General Compatibility Test:
After weighing the weight of the empty packaging material, fill the bulk, then assemble it according to the process requirements and standards, and weigh it again, and place the assembled samples in different test environments as follows:
-20°C 4°C 23°C 40°C 50°C
Light (specific light source conditions)
Cyclic thermal shock
95% humidity, 30°C
The storage time is 4-8 weeks, or a longer period
⦁ Stress cracking test:
Apply the bulk on the assembly stress position of the sample (for example: thread, card position, etc.), and then assemble according to the standard assembly force, and place the assembled samples in groups in different test environments as follows:
23°C 40°C 50°C
The storage time is 4-8 weeks, or a longer period
⦁ Subsequent processing compatibility test:
Apply a layer of bulk on the outer surface of the sample that needs to be tested in subsequent processing (such as printing, electroplating, spraying, hot stamping, etc.), and then place the samples in groups in the following different test environments:
23°C 40°C
cycle thermal shock
95% humidity, 30°C
The storage time is 10 days
After the test period is over, evaluate and record the appearance of the packaging material, some mechanical property data, weight loss rate of the bulk, stress cracking status, aging status, color migration status, fragrance stability, bulk status, etc. of the sample.
The testing methods of various companies vary, but most of them can be summed up as placing the samples in some artificially harsh environmental conditions for a long time, and then evaluating the condition of the samples and the impact on the samples.
Some Development Trends of Compatibility Testing
1. Shorter testing time
Due to the continuous emergence of various new products, all companies hope to take the lead and win the market share first, so domestic companies generally hope that the test can be "fast and accurate"; even the shortest compatibility test in the industry currently requires It takes about four weeks. If the four-week test fails, the packaging materials need to be re-selected, proofed, and tested. Restarting the R&D cycle will inevitably lead to a significant delay in the time to market of the product. This requires the development of more reliable and convenient testing methods to improve efficiency.
2. Higher requirements for biocompatibility (safety)
With the awakening of consumers' safety awareness, any disturbance in product safety may instantly destroy a brand. Therefore, the safety part of the compatibility test has been raised to an unprecedented height. For terminal enterprises, detecting the precipitation of harmful substances requires a lot of resources, and the correlation with the main business is not high. Only a few super-large multinational enterprises may establish special laboratories for special research; the current trend in the industry is, the material supplier or a third party conducts relevant tests and issues relevant reports or certificates. It is worth mentioning that the industry now tends to use food-grade materials in the research and development of cosmetic packaging materials.
3. Integrating simulated consumer usage testing
As the use effect of cosmetics has become more and more closely related to packaging in recent years, in order to verify whether the product can achieve the expected use effect, many companies have included a lot of packaging materials in the compatibility test method group to match the use performance of the bulk. degree detection. For example, for a body sunscreen spray, the packaging materials selected are safe and reasonable, neither chemical incompatibility nor physical incompatibility occurs, but because the bulk contains many powdery raw materials, consumers are pumping out During the process of pumping, the powdery raw materials will partially block the pipeline of the pump body, which will cause the product to be pumped out in a straight line instead of mist. Consumers feel inconvenient to use and directly reduce their desire to buy again.
4. Others
Similar to this, some people have proposed the concept of production compatibility, whether the state of the packaging material and the material body in the production and filling process match, whether the packaging material matches the actual filling process, and so on.
In order to make packaging materials better compatible with consumer use, production and transportation, it is necessary to have in-depth communication and collaboration between multiple departments in the early stage in order to achieve the desired effect, maximize production efficiency, and meet consumer needs to the greatest extent, even surprises.
