In recent years, the tobacco industry has faced growing competition and increasing external pressure from tobacco control initiatives. At the same time, consumer preferences have evolved, leading to higher expectations for cigarette pack quality. As a result, cigarette packaging design has continuously improved to better reflect brand identity and create unique visual effects. To achieve these goals, the use of combined printing processes has become more prevalent in cigarette packaging.
One notable example is the "Seven Wolves" (blue) cigarette pack produced by a company, which employs a complex combination of six different printing techniques: offset printing, gravure printing, hot stamping, UV offset printing, pressure embossing, and die cutting. The production sequence is as follows: three-color blue offset printing → silver text gravure printing → silver underlay hot stamping → two-color gradient blue UV offset printing with water-based varnish → pressure embossing → convex hot stamping on the outer frame of the "Seven Wolves" logo → die cutting.
This article will focus on the key aspects of quality control in each of these seven steps, providing insights and practical advice based on real-world experience.
1. **Ordinary Offset Printing (Three-Color Blue)**
The three colors involved—shading blue, gradient blue, and dark blue—are challenging to print consistently due to their sensitivity to color variation. Ink color must be strictly controlled within a ΔE ≤ 1.5 range. Common issues include ink skinning, water splashing, ink splattering, scratches, and back dirt. Since the printed surface is not glazed after this step, the ink tends to turn reddish when dry. Therefore, spectrophotometric measurements of L, a, and b values are essential to monitor color changes. Proper drying time is also crucial to prevent problems like nozzle imprinting in subsequent gravure printing.
2. **Sheet-Fed Gravure (Silver Text)**
Gravure printing is known for its high plate-making cost and the use of solvents like toluene, which can be harmful to both the environment and workers. During this process, it's common to add solvents such as slow-drying agents or additives to improve ink performance. However, volatile solvents like isopropyl alcohol or n-butanol should never be used. Strict adherence to safety protocols and proper ventilation are necessary. Operators must also monitor ink viscosity, ensure consistent ink levels, and avoid issues like smearing or uneven text thickness.
3. **Hot Stamping (Silver Base)**
This step requires precise registration of the hot stamping pattern relative to the film, along with good adhesion and color consistency. Temperature control is critical—too high and the silver base may darken. Pressure must be moderate to avoid damaging the UV offset printing that follows. Poor adhesion can lead to silver lifting during later steps, causing image loss and damage to equipment. Choosing the right anodized aluminum for the paper type is essential to ensure a strong bond.
4. **UV Offset Printing + Water-Based Varnish**
UV offset printing demands attention to issues like ink drawing, incomplete graphics, and false printing. The application of varnish must be carefully controlled to avoid scratches or nozzle marks. Additionally, the color shift from the initial offset printing to the final UV finish must be managed to maintain consistency. This requires careful monitoring of the first printing stage.
5. **Pressure Embossing**
When embossing the "Seven Wolves" logo, the pressure must be balanced to avoid line bursts or misalignment between the embossing plate and the mold. This step ensures the three-dimensional effect is clear and well-defined without damaging the underlying layers.
6. **Concavo-Convex Hot Stamping (Outer Border of Logo)**
This step is one of the most technically challenging in the entire process. It involves hot stamping after printing, and vice versa, making it prone to defects like jagged edges and ink pulling. Adjusting temperature and pressure, and allowing the anodized aluminum to rest before stamping, can help reduce these issues. Ensuring strong adhesion of the silver base is crucial to prevent ink transfer during hot stamping.
7. **Die Cutting**
Finally, die cutting must be precise to avoid rough edges, improper indentation, or misaligned cuts. Accurate registration and sharp blades are essential for maintaining the integrity of the final product.
By understanding the strengths and limitations of each process, manufacturers can develop effective quality control strategies. Through process optimization, standardization, and the use of quality management tools, the industry can enhance efficiency and meet the evolving demands of the market. Ultimately, mastering these combined printing techniques is key to staying competitive in the future of cigarette packaging.
"Puzzle 3D Eraser Bulk,Puzzle 3D Eraser,Building Blocks Eraser,Toppers Cute Erasers "
Yiwu Shengshang Stationery Co., Ltd. , https://www.ss-stationery.com