Case analysis of curing failure of composite membrane

 

1. Composite PE   Low film strength

Hunan factory production BOPA / PE compound bag, due to the low intensity is returned. 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 the plant was found to color printing, curing chamber thermocouple and heating source in parallel, from the heat source is only 30 cm to 40 cm, under such control, the heat source will be heated in a stopped state for a long time, up to the actual curing temperature is less than 50 ℃. 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.

Composite slip agent when containing a high amount of PE film, to have a choice of adhesive resistant to certain slip agents. 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.

The product uses a 30μ thick PE film , which has a good slip 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.

Some thin transparent temperature sensitive CPP Similarly, pre-composite CPP friction coefficient less than 0.1, but only naturally aged compound.

3. Cooking delamination

A factory in Wenzhou produces marinated egg packaging bags, which are sterilized at 15 ° C for 30 minutes at a food factory . The bags on the upper layers of the sterilizer 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 the company's other technical personnel to the plant found in about 36 hours, when the plant is inconsistent process requirements and practical implementation of real time aging.

 

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