The packaging bag requires low residue and no odor. How to control it?

Currently, to meet manufacturers' requirements for low residue and no odor in packaging bags, higher demands are placed on lamination technology, lamination equipment, and raw materials.

In terms of the lamination process, to reduce harmful solvent residue, there have been corresponding developments in equipment and raw material improvements.

Equipment improvements are moving towards solvent-free lamination, but given the significant investment required for solvent-free lamination equipment, and the fact that most existing domestic equipment is solvent-based, equipment upgrades require a longer time and substantial investment.

Improvements in raw materials are developing towards alcohol-soluble and water-soluble adhesives.

Below, professional flexible packaging manufacturer Shunxingyuan Packaging will briefly analyze how solvent residue is controlled with existing solvent-based lamination equipment and raw materials.

1. Reduce the amount of solvent used.

Try to use a high working concentration. Because less solvent is used, it dries more easily.

2. The equipment's exhaust system should ensure that the air intake volume is greater than the exhaust air volume and that the exhaust ducts are clear.

To avoid residual solvent, sufficient exhaust is needed to remove solvent vapor. Drying conditions should be adjusted according to the substrate, coating weight, and machine speed.

3. During the drying process, it is necessary to appropriately increase and maintain the oven temperature to accelerate the volatilization of solvent in the adhesive, improve adhesion, and ensure lamination quality.

The oven temperature setting should also comprehensively consider factors such as wind speed, machine speed, coating weight, and solvent volatilization rate.

4. The solvent release properties of resins will affect the final solvent residue, requiring adhesive manufacturers to select appropriate resins.

Alcohol-soluble adhesives use ethanol as a solvent, and there are no -NCO groups or highly toxic free TDI, MDI, and other aromatic isocyanate molecules in the monomer; as a "green solvent", ethanol's toxicity is also far lower than ethyl acetate. Therefore, using alcohol-soluble adhesives for lamination will not produce residual components like toluene, ethyl acetate, TDI, MDI, only trace amounts of alcohol residue, which can greatly reduce solvent residue.

Generally, solvent residue is 0.5-1mg/m2.

5. During the lamination process, when meeting the composite strength requirements, use as low a coating weight as possible.

6. When composite products are curing, ensure smooth ventilation in the curing room and sufficient curing time.

Ventilation in the curing chamber is also very important; sufficient ventilation can further reduce solvent residue and also shorten curing time.

7. Avoid residual solvent from printing.

Improve printing machine drying conditions to ensure the printed film is completely dry.

8. Ensure ventilation in the operating environment to ensure sufficient discharge of solvent gases from the environment.

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