PET (printed) laminated to BOPA and then to CPP (three-layer pouch): after converting, the PET peels off entirely with a gentle pull — what should be done?

Hunan Shangpin Packaging: Regular pouch: PET (printed) laminated to BOPA and then to CPP (three-layer pouch). After being made into finished pouches, the PET peels off entirely with a gentle pull, and there is not a trace of ink on the laminated BOPA layer. What is going on?

Lin Xiwen, Yawei Color Printing: What ink was used?

Hunan Shangpin Packaging: Retort ink was used.

Wang, Xin'an Packaging: 1. No adhesive applied or adhesive coating weight too low; 2. Abnormal adhesive quality; 3. Almost no pressure from the lamination rollers during the two-layer lamination; 4. The wrong corona-treated side was used during PET printing, or the corona treatment value was insufficient (in this case the ink usually transfers to the other layer — for example, most of the ink and adhesive would transfer to the BOPA).

Hunan Shangpin Packaging: This time we used nylon with corona treatment on one side only, that is, nylon for printing.

Jiang Wei: Isn't printing grade better? Corona treatment definitely isn't the problem.

Hunan Shangpin Packaging: My colleague said double-sided corona treatment would solve this problem.

Jiang Wei: Many cold-formable aluminum-nylon 2.5c structures are printing grade.

Xiao Xia, Hubei Dry Lamination: When laminating with PET, the normal unwinding should be the corona-treated side of the nylon laminated to the PET.

Jiang Wei: The adhesive coating weight should exceed 3g/m2.

Hunan Shangpin Packaging: PET laminated to nylon is fine; it is the CPP layer that is not firmly bonded. That is, the lamination between the nylon and the CPP is not firm.

Jiang Wei: Because PET is a material with very good strength, and PA has even better strength, when these two materials are combined, the adhesive must provide sufficient peel strength. Otherwise delamination occurs very easily.

Xiao Xia, Hubei Dry Lamination: You should still check whether there is any problem with the CPP.

Hunan Shangpin Packaging: The CPP I used was also from stock, because this CPP had been used for many production runs before and there were never any problems.

Fei, Flexible Packaging Newcomer: You can also check whether it is the same batch of CPP or the same production date or similar.

Xiao Xia, Hubei Dry Lamination: Whether from stock or newly purchased! Instability is not just about the surface. Weather and environment, and the adjustment of the lamination process over time, are all related to the impact on product quality.

Wang, Xin'an Packaging: I have encountered CPP that had been in stock for a long time being laminated to PA; right off the machine there was almost no initial tack, and it opened up completely with a pull. After switching to new CPP, the problem was solved.

Jiang Wei: If CPP is stored for too long, the corona treatment becomes insufficient and additives migrate, affecting peel strength.

Wang, Xin'an Packaging: Our analysis was the massive migration of CPP additives; I don't know whether that is reliable.

Hunan Shangpin Packaging: It seems to be a problem with the CPP. We will run a test shortly. Thank you. (If you have different opinions, you are welcome to continue the discussion at Packaging Frontier Network www.pack168.com. Everyone is welcome to continue exchanging views on our website; friends who provide more solutions can receive reading credits for technical articles on the website. To request credits, please contact Xiao Yang: 15813331361, Xiao Lai: 18475695660)