When the composite film is cured, it is easy to cause problems such as low strength, increased friction coefficient, and delamination. The editor of Huayin has combined the actual problems of the printing factory with the above problems, and after testing, has given the corresponding solutions. I hope to help you!
1. Low composite PE film strength
A factory in Hunan produced BOPA / PE bags, which were returned due to low strength. After peeling off the two layers of film and rubbing with your fingers on the PE film, there is a smooth feeling of friction between the two fingers. The slip agent in the film is more precipitated. The adhesive used in this product is PU-1850 which has certain resistance to slip agent.
After arriving at the color printing factory, it was found that the temperature measurement thermocouple in the curing room was parallel to the heating source, only 30 cm to 40 cm away from the heating source. Under such control, the heating source would stop heating for a long time, and the actual curing temperature could not reach 50 ℃ of. And the aging time when the power is turned on is less than 16 hours. Adjust the thermocouple position, extend the curing time, and the peel strength meets the requirements.
When compounding a PE film with a high content of slip agent, an adhesive with certain resistance to slip agent should be selected. The film roll enters the curing room as soon as possible after being taken off the machine, and appropriately increases the curing temperature. Generally, ester-soluble two-component polyurethane adhesives have poor natural curing properties and slip resistance.
2. Increased friction coefficient
A factory in Guangdong produces roll film with BOPP / VM-PET / PE structure, and there has been no problem in winter production. Produced in June, the friction coefficient increased and the packaging machine could not be used normally. Change to natural aging, the film roll can not be used.
This product uses a 30μ thick PE film, which has good slip properties before compounding. During the lamination, the cooling roller does not pass cold water, and the surface of the cooling roller is warm. The heat of the film from the oven belt is still there before winding, and the film is also warm during winding. Although it is naturally matured in the workshop, the summer temperature is high (the workshop temperature is 30 ° C at 10 am), the heat of the film roll is not easy to dissipate, and it is actually in a hot state.
Take the compound film on site and put it in two environments of 27 ° C and 45 ° C for about 20 hours. The slip performance at 27 ° C is good. The compound film placed at 45 ° C is astringent, and the slip performance is significantly reduced. The effect of product slippage is greater.
Similar to the temperature sensitivity of some thin transparent CPPs, the friction coefficient of CPP before compounding is lower than 0.1, but it can only be cured naturally after compounding.
3. Cooking delamination
A factory in Wenzhou produces marinated egg packaging bags and sterilizes them at 115 ° C for 30 minutes at the food factory. The bags on the layers of the sterilization pot have BOPA delamination, and the Huaimo ink is transferred to the CPP. The technical staff of the color printing factory believes that the quality of the adhesive and the amount of glue are sufficient to clean the product. The curing at 50 ° C to 55 ° C for 48 hours is also satisfactory. The problem lies in the possibility of ink.
The sample bag was aged again at 55 ° C for 24 hours. There was no delamination after cooking at 121 ° C for 30 minutes; all the uncooked samples that were cooked together also showed delamination. The direct manifestation of this problem is ink transfer, and the cause of this phenomenon is insufficient curing. Later, when other technicians of the company arrived at the plant, they found that the actual curing time was about 36 hours, and the process requirements of the plant were inconsistent with the actual implementation.
Micellar Cleansing Water,SkinActive Micellar Cleansing Water,Micellar Water,Organic micellar water,Micellar water for oily skin
Ningbo Roni Cosmetic Co,.Ltd , https://www.ronicosmetics.com