What is the reason for the foaming of nylon bags that do not stick to silicone? How to solve it?

The problem of non stick and foaming of nylon wrapped silicone is a common challenge in the manufacturing industry, especially in the field of composite material processing. This phenomenon often stems from a combination of factors such as material properties, processing techniques, environmental control, and operational standards.

1、 Cause analysis

1. Material characteristics

Nylon, as a thermoplastic material, has unique physical and chemical properties. The amide bonds in its molecular structure endow nylon with excellent wear resistance, oil resistance, and chemical corrosion resistance, but at the same time, it also leads to poor thermal stability and is prone to thermal decomposition and gas production during processing. In addition, plasticizers, masterbatch and other additives are often added to nylon during injection molding, which may affect the bonding performance between nylon and silicone.

Silicone is a highly elastic and high-temperature resistant rubber material with low surface energy, making it difficult to form strong chemical bonds with other materials. Therefore, without special treatment, direct contact between nylon and silicone often fails to achieve the desired bonding effect.

2. Processing technology

Injection molding temperature and time: If the injection molding temperature is too high or the time is too long, it will cause the degradation of nylon material, produce gases and volatile substances, thereby forming bubbles at the interface between nylon and silicone, affecting the bonding quality.

Mold design and exhaust: Unreasonable mold design or poor exhaust can also lead to the inability to timely release gas during the injection molding process, resulting in the formation of bubbles inside the product.
Adhesive selection and use: Improper selection of adhesive type or improper coating process, such as insufficient solid content of adhesive, uneven coating, insufficient drying, etc., can all affect the bonding effect between nylon and silicone.

3. Environmental control

The humidity, temperature, and cleanliness in the production environment also have a significant impact on the adhesion between nylon and silicone. Excessive humidity can cause nylon to absorb moisture, reducing its adhesive properties; If the temperature is too high, it may accelerate the curing reaction of the adhesive, causing stress concentration inside the bonding layer, thereby triggering bubbles or peeling.

4. Operating standards

The technical level, operating habits, and understanding of the process of operators are also important factors affecting the quality of nylon and silicone bonding. Improper operation may lead to uneven glue application, incomplete mold closure, inaccurate control of baking temperature and time, and other issues.

2、 Solution

1. Optimize material selection

Choose silicone materials with good compatibility with nylon, or use specially formulated silicone glue to improve bonding strength.
Try to minimize the addition of plasticizers, masterbatch and other additives in nylon to reduce their adverse effects on bonding performance.

2. Improve processing technology

Accurately control the injection temperature and time to avoid excessive degradation of nylon material.
Optimize mold design to ensure smooth exhaust and reduce the possibility of bubble generation.
Use the appropriate type of adhesive and follow the manufacturer’s recommended coating process to ensure that the adhesive is evenly applied and fully dried.

3. Strengthen environmental control

Maintain the cleanliness of the production environment and reduce pollution from dust and impurities.
Control the humidity and temperature of the production environment to ensure that processing is carried out under suitable conditions.

4. Improve operational standards

Provide professional training to operators to improve their understanding and mastery of the process.
Develop detailed operating procedures and work instructions to ensure that every step of the operation complies with standards.
Strengthen quality inspection and control, promptly identify and correct problems.

5. Special handling measures

For nylon wrapped silicone products that have already experienced non stick or foaming, the following special treatment measures can be attempted for repair:
Use solvents such as toluene to remove oil stains from the surface of nylon and improve its surface energy.
Apply a layer of primer or tackifier to improve the adhesion between nylon and silicone.
Apply a thin layer of glue or adhesive on the surface of silicone, and then bond it with nylon.
For severe foaming issues, reprocessing or scrapping may be necessary.
In summary, the problem of non stick and foaming of nylon wrapped silicone involves multiple factors, which need to be comprehensively solved from multiple aspects such as material selection, processing technology, environmental control, and operating standards. By continuously optimizing and improving the processes and technical means of each link, the bonding quality between nylon and silicone can be significantly improved to meet the requirements of product use.