Food plastic flexible packaging is sometimes rejected by users due to its odor, and there are also incidents of compensation for contaminated food with unpleasant odors inside. The odor of food packaging bags mainly comes from printing ink and ink solvents, or composite adhesives and composite adhesive solvents, with some coming from the inner film of composite packaging.
Therefore, when making composite packaging, the following points should be noted:
(1) The design of printing patterns should choose few colors and monochrome elements, and try to avoid printing patterns with a solid base and full page.
(2) When selecting printing ink, do not use surface printing ink with a strong odor. Do not use high boiling point solvents containing impurities, such as tar benzene, mixed benzene, or recycled solvents.
(3) Do not use single component PS composite adhesives with high odor for compounding.
(4) The inner film material used for composite should be checked for odor, and PE film with fillers should not be used as the inner substrate for composite.
(5) Strive to increase printing speed, reduce the viscosity of printing ink as much as possible, decrease the amount of ink applied, maintain smooth ventilation in the drying oven and workshop, and minimize ink and ink solvent residue.
(6) To maintain a smooth exhaust in the drying duct of the laminating machine, an appropriate amount of glue should be applied, and ester solvents containing impurities and moisture should not be used (the poured solvent and prepared glue should be covered to prevent inhaling moisture from the air). The temperature of the laminating machine's hot drum should be around 70 ℃.
The most crucial thing is to choose films with good barrier properties as the inner layer material for composite packaging. This way, even if there are solvent residues and odors, they will not come into contact with food and cause it to be contaminated with unpleasant odors. For example, using PE film with poor barrier properties as the inner layer material for composite packaging, the residual odor of the adhesive can easily penetrate and contaminate the food inside
