Soft plastic printing process Q

[Chinese Packaging Network News] Is it possible to use EVA film for packaging clothes?

Most clothing is packaged using heat-sealable BOPP film, which offers excellent clarity and a seamless appearance. The garment pocket is formed by heat-sealing the bag, making it visually appealing and allowing the style and craftsmanship of the clothing to be clearly visible. These bags are typically sealed with adhesive or embossed buckles, enabling them to be opened and re-closed easily. While EVA film provides better softness compared to BOPP, it lacks the stiffness and transparency of BOPP. If the requirements aren't too strict, EVA can be used as an alternative to heat-sealable BOPP. However, the cost may not be lower, as EVA pellets are relatively expensive at around 10,000 yuan per ton.

How can waste SBS material be recycled?

To recycle waste SBS material, you can add cyclohexane plasticizer and new SBS pellets to reshape it into usable form. This process helps restore the material’s properties and makes it suitable for reuse in various applications.

When printing on aluminum foil using polyamide ink, the print shows good fastness, but after cooking at 100°C for 30 minutes, the ink begins to peel off. How can this issue be resolved?

This indicates that the polyamide ink used on aluminum foil is not suitable for high-temperature cooking. To address this, a high-temperature resistant composite ink can be used for reverse printing on BOPET film, followed by dry lamination with aluminum foil to create a heat-resistant packaging bag. Alternatively, a two-component acrylic high-temperature steaming ink, cross-linked using a silane coupling agent, can be used instead of one-component nylon ink. This type of ink, as described in the "Encyclopedia of China Plastic Products," offers excellent resistance to high temperatures and prevents peeling even after 100 minutes at 100°C.

Why do single-layer liquid packaging milk bags break during 100°C, 30-minute sterilization?

A 100°C, 30-minute high-temperature sterilization requires vacuum sealing. Otherwise, as the temperature rises, the air inside the bag expands significantly, increasing internal pressure by more than ten times. Standard plastic bags cannot withstand such pressure, leading to rupture. For simple milk packaging, pasteurization at 85°C for 30 minutes is usually sufficient. After sterilization, the plastic should be aseptically packaged in a sterile environment using hydrogen peroxide or UV light. Pasteurized milk has a short shelf life—typically only 1–2 days under refrigeration. This is because pasteurization eliminates pathogenic bacteria but leaves molds and yeasts intact, which can multiply at room temperature and spoil the milk quickly.