If, during production, thermal molding or subsequent use, the high barrier bubble film appears blistering, layered or partially separated, it will not only affect the appearance of the blister pack, but also its barrier performance and sealing reliability. This is crucial for products with strict packaging requirements such as medicines, food and health products. In practice, such defects are rarely caused by a single factor; rather, they are often caused by a combination of factors such as material structure, lamination processes, temperature, humidity, storage conditions and equipment parameters.
1.Insufficient Interlayer Adhesion
High-barrier bubble membranes are usually composed of a variety of materials and must be securely bonded together by laminating. In laminating process, the selection of inappropriate adhesive, coating weight, temperature and pressure parameters control instability will lead to inadequate interlayer adhesion.
During thermal molding, the film undergoes heating, stretching and cooling. Local localized delamination occur if the thermal shrinkage rates of the component material is significantly different, coupled with a weak binding between layers.
Therefore, the supplier must give priority to controlling lamination strength, the state of the adhesive and the compatibility of the various material layers in production process.
2.Residual Gases or solvents during stratification
When a high barrier bubble film is produced using an adhesive lamination process, any partially evaporated solvent or trapped air in the laminating process expands when heated, causing bubbles to form.
This phenomenon is more pronounced in the process of high-temperature thermoforming. As the temperature rises, the residue, or trapped gas, expands, causing the laminated layers in some areas to bulge.
Therefore, before further processing, the weight of the adhesive layer, drying conditions and curing time must be strictly controlled to ensure that the adhesive material reaches a stable, prescribed state.
3.Improper Thermoforming Temperature Settings
High resistance blister membranes require to be heated to form a final shape. If the heating temperature is set too high, the thermal shrinkage between different material layers can be very different, which increases the risk of delamination. If the temperature is too low, the material may not soften sufficiently, leading to molding difficulties or excessive local stress.
In practice, it cannot simply be said that "the warmer the temperature, the easier the molding." Instead, the temperature should be adjusted gradually –taking into account the film 's structure, thickness, molding depth, and equipment specifications –to ensure that the material is in optimum molding condition.
4. Instability of forming pressure or equipment parameters
In addition to temperature, molding pressure, vacuum level, molding speed, cooling conditions and other factors will also affect the final state of the blister film.
For example, excessive molding speed may lead to uneven heating and stretching of the material, while unstable vacuum or pressure control may lead to localized molding defects. In the case of deep cavity blisters, the membrane must undergo significant stretching, and any potential weaknesses in adhesion between the material layers are more likely to be exposed.
Therefore, when switching to a high resistance bubble membrane of a different specification, it is recommended to revalidate the device parameters rather than simply continue to use the previous material settings.
5. Moisture exposure or inappropriate storage conditions
Some highly resistant films are sensitive to temperature and humidity. If the material is exposed to high humidity for a long time, or if the packaging is not properly sealed, problems such as blistering or decolletage may occur during processing due to humidity or other environmental factors.
In addition, significant temperature fluctuations in the storage environment can affect material size stability and interlayer integrity.
It is recommended that the packaging be kept intact during transport and storage and that the material be stored at the temperature and humidity conditions specified by the supplier. If the packaging is opened but the material is not used immediately, appropriate measures should be taken to prevent moisture exposure.
6. How to minimize blistering and layering of highly resistant blister membranes?
From the point of view of suppliers and end-users, control can be achieved through:
First, check the structure of the material. Verify that the layers are compatible and that the lamination (bond) strength meets the requirements of the specific thermoforming process.
Second, optimize the lamination process. Strict control of adhesive coating weight, drying conditions and curing time, to minimize residual solvents or trapped air.
Third, adjust thermoforming parameters. According to the specific characteristics of the film, the heating temperature, molding pressure, speed and cooling conditions are fine-tuned.
Finally, strengthen warehouse management. Avoid exposing materials to humidity, direct sunlight or extreme temperatures for long periods of time.
If the problem persists, it is recommended to systematically investigate the film material itself, the composite layer, equipment parameters and the processing environment. Suppliers can also help determine the root cause by conducting interlayer stripping strength analysis, thickness uniformity checks, barrier performance evaluation and thermoforming trials.
Frequently Asked Questions
Q1: Does blistering of a highly resistant blister membrane mean a material quality problem?
Not necessarily. Foaming may be related to the structure of the material, but it could also result from laminating processes, storage conditions or thermoforming parameters. A comprehensive assessment based on specific production conditions is required.
Q2: Why are layers more likely to occur after thermal forming?
Heating involves heating and stretching the film. If the thermal shrinkage between layers is very different or the adhesion between layers is insufficient, layering may occur during this process.
Q3: Does dampness cause film blistering?
Yes, it's possible. For water-sensitive materials, exposure can lead to irregularities in heating and processing stages; proper moisture storage is therefore essential.
Question 4: How to determine whether a problem arises from the lamination process or from the thermoforming process?
You can check the stripping strength between layers and compare the state of the material before and after thermal molding. If the original film is showing signs of decolletage, the lamination process should be investigated first. If the original film is intact but there are problems forming, the focus should shift to equipment and processing parameters.
Q5: How should I report foaming problems with high barrier foam film to my supplier?
Details such as material specifications, batch numbers, equipment used, thermoforming temperatures, molding speed, storage conditions and specific locations of blisters are recommended (with photos). This information will enable suppliers to analyse the reasons more accurately.
