In recent developments, the tobacco industry has conducted in-depth analysis of volatile organic compounds (VOCs) found in cigarette packaging and is considering revisions to the existing VOC limit standards. The new regulation maintains the original benzene limit as a single veto, while all OTHER 15 compounds must not exceed their respective thresholds. This updated standard has already been piloted in certain regions. As a result, ensuring that gravure-printed cigarette packages meet these new requirements has become a top priority for printing companies.
According to testing data on raw materials, both the solvents used for ink dilution and the ink itself are the primary contributors to VOC content in cigarette packaging. Among these, the ink plays the most critical role, directly determining the overall VOC levels. Therefore, improving the VOC content of the ink is essential to meeting the new standards.
In actual production, numerous factors influence VOC levels in cigarette packaging. To simplify analysis, we selected a typical traditional solvent-based gravure package—7-color printing with large color blocks overprinted on aluminumized material, using solvent-based gravure inks—as a case study. Before improvements, the VOC test results showed a total exceeding the standard by 18.9 units. After 10–15 days of storage, this decreased to between 7 and 10, which met the overall requirement but still failed to satisfy the single-component limits. Thus, further optimization was necessary.
Two improvement strategies were developed based on real-world production conditions:
**Option One: Reformulating the Solvent-Based Ink**
This approach focuses on maintaining the existing solvent-based ink system while reducing the VOC content of individual components. Since large color blocks have the greatest impact on VOC levels, the three main colors were prioritized for reformulation. The goal was to adjust the solvent structure and proportions without compromising ink performance. Through multiple trials and adjustments, an optimal formula was determined. The improved results showed a reduced over-standard multiple of 4.4, and after 13–15 days of storage, all individual components met the required standards.
To achieve the best VOC control, several operational adjustments were made:
- **Solvent Management:** Adjusting the amount of high-limit solvents like ethanol and n-propyl acetate while reducing low-limit solvents such as n-butyl acetate and isopropyl alcohol.
- **Drying Control:** Optimizing drying temperature and airflow to ensure complete solvent evaporation.
- **Monitoring:** Strengthening VOC detection during the printing process to prevent inconsistencies.
- **Ink Compatibility:** Ensuring no mixing of inks from different manufacturers, especially concerning benzene, which has a very strict limit.
- **Storage Conditions:** Considering factors like storage time and ventilation, which can significantly affect VOC levels.
- **Production Planning:** Allowing at least 15 days between production and delivery to enable natural VOC evaporation.
**Option Two: Switching to Water-Based Ink**
The second strategy aimed to minimize process changes while achieving better VOC control. By introducing water-based ink for one of the three solid colors, the VOC content was successfully brought within all 15 compound limits. However, this required collaboration across ink formulation, plate making, and printing processes.
Key steps included:
- **Plate Adjustment:** Preparing new printing plates suitable for water-based inks with shallower cells (15–25 μm compared to 45–55 μm for solvent-based inks).
- **Drying Equipment Modification:** Enhancing oven power, air volume, and length to improve drying efficiency.
- **Performance Monitoring:** Closely observing adhesion, drying, hue, and gloss to maintain quality.
- **Additives Use:** Incorporating dispersants, defoamers, and leveling agents to enhance ink performance.
- **Operational Standards:** Preventing mixing with solvent-based inks and maintaining clean printing plates to avoid issues.
Both options demonstrate effective paths toward compliance with the new VOC regulations, highlighting the importance of careful planning, collaboration, and continuous monitoring in the printing process.
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