Zhejiang Ukpack Packaging Co,.ltd

Packaging Your Future

Packaging material compatibility test

Time:2022-03-18 16:48:11Hits:185

Testing is not everything,

But it is absolutely impossible not to test.

For packaging testing, we want to “improve efficiency” and save the longest time-consuming compatibility testing, especially those that cannot be used. Of course, the colleagues in the marketing department and the project department have the biggest headache for such remarks. In their view, this is simply dogmatism.

Several years ago, I met a private cosmetics enterprise that has not yet established a packaging testing mechanism. Their formulator told me that if the packaging materials are used, we can just test the compatibility; At that time, I wanted to tease her, so I deliberately asked, “can compatibility be unpredictable?” She didn’t understand my real intention, and was really anxious: “what can I do if something happens? When the packaging material and material body are broken, you don’t know! You’re really funny!” So I didn’t dare to despise this simplest theory, because it just reveals such a truth to us: today, with the rapid development of material science, the use of good materials can indeed help our end customers save a lot of testing work, but compatibility testing alone can’t be omitted.

Definition of compatibility test

The compatibility between cosmetic packaging and its contents broadly refers to the interaction between plastic packaging and cosmetics, including chemical compatibility, physical compatibility and biological compatibility.

The following briefly describes the specific conditions of various incompatibilities:

Chemical incompatibility: the chemical components of packaging materials. During processing, the decomposition products have a chemical reaction with the components of cosmetics, which has an adverse impact on cosmetics or packaging materials; Chemical incompatibility is manifested in the change of appearance and smell of packaging materials or cosmetics. For example:

Yellowing of Liquid


Pink packaging material yellowing


Biocompatibility: some substances in packaging materials migrate into cosmetics, which has an adverse impact on users; It shows that the dissolution amount of harmful substances exceeds the measurement specified in the relevant hygienic standards or specifications of cosmetics in 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 components of cosmetics, the amount of dissolved is very small, and the dissolved product is harmless to users, this dissolution phenomenon belongs to normal compatibility. For example:

The colorant in the plastic precipitates into the contents

The contents were originally off white

Physical incompatibility: physical changes have taken place between the packaging material and the contents due to the influence of each other; Physical incompatibility is manifested by penetration, adsorption, crack, cracking, dissolution, etc. In test judgment, physical incompatibility is often misjudged as chemical incompatibility, because the phenomenon of physical incompatibility is obvious and the reaction is violent. For example:

surface crack

Stress cracking

n view of the fact that the plastics used in cosmetic packaging materials have certain solvent resistance and the cosmetics are relatively mild, the incompatibility between cosmetics and packaging materials is more physical incompatibility.

In addition, through fine chemical quantitative analysis experiments, it is proved that the incompatibility between cosmetic packaging materials and their contents usually does not appear in a single form.

About compatibility test results

In fact, the expression form of compatibility test results is relatively complex. Usually, many colleagues will ask that since the compatibility is unqualified, all samples should react with the contents, and each sample should have problems. Why are there good and bad samples at the same temperature? In fact, there is a certain rate of unqualified compatibility. For example, when 10 samples are tested at 40 ℃, only 2 samples are cracked, and the remaining 8 samples are intact. However, when you expand the number of samples to hundreds of samples, you will find that the number of cracked samples has expanded to dozens; By analogy, if such packaging materials are put into mass production, the final problem will not be a small number

Compatibility accident cases

Case 1

A century old luxury enterprise added sunscreen to a base makeup product developed in the early stage. Since most plastic containers at that time were made of pet, they didn’t think much and still used containers of the same material; Moreover, the testing mechanism of the whole company was not perfect at that time. As a result, after a period of time, they were very frightened to find that the bottle was cracked! After research, it was found that the sunscreen component in the content was physically incompatible with the PET container, so the company quickly updated the product; Since then, word of mouth in the company has said that PET packaging materials are strictly prohibited for products with sunscreen ingredients! Of course, this sentence is not entirely accurate due to the influence of the technical level at that 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 cosmetics giant in the world, a foundation liquid product, because of the original packaging materials, the contents only changed the color, so after assessment, it can be removed from the compatibility test. After the product is listed, the quality department’s room temperature stability test reports the color of the liquid in the inner wall of the package, which is flaky with the inner wall of the plastic. After cleaning by water and solvent, there is no way to clean it. This case also fully proves that the compatibility test can not be omitted.

Examples of general practice of compatibility test: time, test conditions

Take the compatibility test scheme of a cosmetics giant as an example:

(the following test conditions can be selected according to different conditions of products)

● general compatibility test:

After weighing the weight of empty packaging materials, fill the contents, then assemble them according to the process requirements and standards, weigh them again, and place the assembled samples in the following different test environments:

-20 ℃4 ℃23 ℃40 ℃50 ℃light (specific light source conditions) cyclic thermal shock 95% humidity, 30 ℃

The storage time is 4-8 weeks, or longer

● stress cracking test:

Coat the contents at the assembly stress position of the sample (e.g. thread, clamping position, etc.), then assemble according to the standard assembly force, and place the assembled samples in the following different test environments:

23℃40℃50℃

The storage time is 4-8 weeks, or longer

● post processing compatibility test:

Apply a layer of contents at the post processing (e.g. printing, electroplating, spraying, hot stamping, etc.) on the outer surface of the sample to be tested, and then place the samples in the following different test environments:

23 ℃40 ℃cyclic thermal shock, 95% humidity, 30 ℃

The storage time is 10 days

After the end of the test cycle, evaluate and record the appearance of the packaging material, some mechanical property data, weight loss rate of the content, stress rupture condition, aging condition, color migration condition, flavor stability, content condition, etc.

The testing methods of various companies are different, but most of them can be summarized as placing the samples in some more severe man-made environmental conditions for a long time, and then evaluating the condition and impact of the samples.

Establishment of compatibility laboratory

When it comes to the compatibility laboratory, everyone will think of various test chambers with different height, weight and temperature, so there is no need to repeat these test chambers; What should be mentioned here is the allocation of human resources.

Since compatibility testing involves both packaging materials and contents, it must be a field of cross-border cooperation; Many recruitment cases have been encountered before. They all hope to recruit talents who understand both packaging materials and contents. They don’t want a person to do packaging materials, but only know packaging materials; Of course, many colleagues feel that such recruitment requirements are indeed somewhat high and not very practical; But the theory is correct. A mature compatibility laboratory should be equipped with experts to judge the condition of packaging materials and the condition of contents. If there is no condition to establish a special compatibility laboratory, at least two departments must cooperate to test in order to obtain reliable results. In a recent case, a company stipulated that the compatibility test was led by the packaging material department, and the Engineer in charge of the packaging material test thought that the judgment of the content was generally carried out by himself. There was no need to fill in the opinions of the content developer in the report, and it really did so in the actual work. Fortunately, the management found it in time, It is required that the final report can be issued only after the confirmation of the content department.

Some development trends of compatibility testing

01 reduced test time

Due to the endless emergence of various new products, all companies hope to take the lead and seize the market share, so domestic enterprises generally hope that the test can be “fast and accurate”; At present, even the shortest compatibility test in the industry takes about four weeks. If the four week test fails, the packaging materials need to be re selected, proofed and tested. Reopening the R & D cycle will inevitably lead to a significant delay in the time to market. This requires the development of more reliable and convenient test methods to improve efficiency.

Higher requirements for biocompatibility (02)

With the awakening of consumers’ safety awareness, any disturbance in product safety may destroy a brand in an instant. Therefore, the safety part of compatibility test has been raised to an unprecedented height. For terminal enterprises, detecting the amount of harmful substances needs to consume 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; At present, the trend in the industry is that material suppliers or third parties conduct relevant tests and issue relevant reports or certificates. It is worth mentioning that the industry now tends to apply food grade materials to the research and development of cosmetic packaging materials.

03 integration simulation consumer use test

In recent years, the relationship between the use effect of cosmetics and packaging has become closer and closer. In order to verify whether the products can achieve the expected use effect, many companies have included a lot of performance matching tests between packaging materials and contents in the compatibility test method group. For example, a body spray Sunscreen Spray is safe and reasonable, which is neither chemical incompatibility nor physical incompatibility. However, because the contents contain many powdery raw materials, during the process of pumping out the material, the powder material will partially block the pump body pipeline, which will lead to the form of the pump not foggy but straight, and it is not convenient for consumers to use it. Directly reduces the desire to buy again.

04 others

Similarly, some people have put forward the concept of production compatibility, whether the state of packaging materials and materials in the production and filling process is matched, whether the packaging materials are matched with the actual filling process, and so on.

In order to make the packaging materials more “compatible” with the use, production and transportation of consumers, it is inevitable to need the in-depth communication and cooperation of multiple departments in the early stage, so as to achieve the expected effect, maximize the production efficiency, meet the needs of consumers to the greatest extent, and even bring surprises.