In recent months, the tobacco industry has conducted a comprehensive analysis of volatile organic compounds (VOCs) found in cigarette packaging and is planning to revise the current VOC limit standards. Specifically, benzene will remain subject to a single veto, meaning it must not exceed its original threshold. At the same time, each of the OTHER 15 compounds included in the limit criteria must also stay within the prescribed limits. This updated regulation is now being tested in several regions, and the challenge for cigarette packaging printers is now to ensure that their gravure-printed packs meet these new requirements.
According to testing data on raw materials, two main factors influence the VOC content in cigarette packaging: the solvent used to dilute the ink and the ink itself. Among these, the ink plays the most critical role, as it directly determines the overall VOC levels. Therefore, improving the VOC content of the ink is essential to meeting the new standards.
In actual production, numerous variables can affect VOC levels. To simplify the discussion, a typical traditional solvent-based gravure pack was selected for analysis. This pack uses seven colors, with three large color blocks overprinted on aluminized material, and relies on solvent-based gravure inks. Before any improvements, the VOC test results showed a total exceeding the standard by 18.9 units. After 10–15 days of storage, this value dropped to between 7 and 10, which is below the 15-time limit but still failed to meet the single-indicator requirement. This prompted the development of two improvement strategies.
Option One involves reformulating the solvent-based ink. The goal is to reduce the VOC content of individual components while maintaining ink performance. Since large color blocks have the greatest impact on VOC levels, the inks used for the three main colors were targeted for improvement. Adjustments were made to the solvent composition and proportions to achieve the best possible balance. After extensive trials, the improved ink formulation resulted in an over-standard multiple of 4.4. After 13–15 days of storage, all individual VOCs met the required standards.
However, successful implementation requires coordination across all aspects of production. For instance, the solvents used for dilution should be adjusted based on their volatility and solvency. Higher-limit solvents like ethanol and n-propyl acetate may be increased, while lower-limit ones like n-butyl acetate and isopropyl alcohol should be reduced. During printing, the drying temperature and air volume must be carefully controlled to ensure complete solvent evaporation. Regular monitoring of VOC levels is also crucial to prevent process-related fluctuations.
During the improvement phase, ink properties must be closely monitored, and any issues should be addressed promptly. Small-scale trials are recommended before full production to avoid unexpected problems. Additionally, when mixing inks from different manufacturers, special attention must be given to benzene levels, as even small amounts can cause non-compliance. Benzene is particularly sensitive, and mixing inks has led to over-standard results in some cases.
The VOC content in cigarette packs is also influenced by factors such as post-press processing, storage conditions, and duration. Packs that undergo die-cutting and are stored in well-ventilated areas for longer periods tend to have lower VOC levels. Most customers require a minimum 15-day interval between production and delivery, allowing time for VOCs to dissipate naturally.
Option Two involves switching to water-based inks. This approach aims to achieve better VOC control with minimal changes to the existing process. In practice, one color was replaced with a water-based ink, and the results showed that all 15 compounds met the required standards. However, this transition required adjustments in plate making and printing equipment. The printing plates needed to be reworked, with cell depth reduced from 45–55 μm to 15–25 μm. Drying systems were also modified, including increasing oven power, airflow, and length to improve drying efficiency.
Water-based inks also require careful handling during printing. Their drying performance may differ, so adjustments in the water-to-ethanol ratio or the addition of quick-drying agents might be necessary. Ink adhesion, gloss, and color consistency should be closely monitored. Mixing with solvent-based inks is strictly prohibited, and proper cleaning procedures must be followed to maintain print quality.
Finally, additives such as dispersants, defoamers, and leveling agents can be used to enhance the performance of water-based inks. These steps collectively contribute to a more sustainable and compliant packaging solution.
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