The printing method of food packaging

Gravure printing and flexographic printing require quite large equipment.

 

Introduction

 

The printing method of food packaging paper significantly influences the quality of the product, the brand image, and even the safety of the food. In particular, gravure printing and flexographic printing are the most commonly used methods in food packaging paper printing. However, considerations about the impact of these printing methods on the environment and the harmfulness to the human body have become increasingly important. Let's take a look at the printing methods of packaging paper - gravure printing, and flexographic printing. Gravure printing is widely used in food packaging paper printing due to its high resolution and extensive color expressiveness.

 

However, because this method is a printing method for mass production, the waste generated during the printing process and the use of chemical substances can negatively impact the environment. Also, the ink used in gravure printing may contain chemicals harmful to the human body, which can pose a direct threat to food safety. On the other hand, flexographic printing is known as a more environmentally friendly printing method than gravure printing. This method minimizes the use of chemical substances by using a smaller amount of ink than gravure printing, and it can also reduce waste generated during the printing process.

 

However, flexographic printing is not entirely environmentally friendly, and considerations about waste water treatment and energy consumption during the printing process are needed. Thus, food packaging paper printing is not a simple matter of decorating the appearance of a product, but a complex issue that must consider the impact on the environment and human health. Increasing understanding and awareness of this is one of the important responsibilities of food packaging paper manufacturers. Gravure Printing Gravure refers to "intaglio printing" in French. For this, an intaglio plate is required, and a circular plate is made for automatic and continuous processes. The inks entering the engraved grooves of the created circular intaglio plate are transferred to the film, expressing the image.

 

Let's take a look at the procedure.

 

1. Making a copper plate: First, the design to be printed is created on a computer. This design is engraved on a copper plate using a laser. The depth of the engraving varies depending on the darkness of the color to be printed.

 

2. Chrome plating: Once the copper plate is made, the surface undergoes a chrome plating process. At this stage, tiny grooves are created on the surface of the copper plate, which helps to hold the ink better and improve print quality.

 

3. Ink application: Once the copper plate is ready, the ink of the color to be printed is poured into a tray, and one side of the copper plate touches the tray and the other side touches the film. As the copper plate rotates, the ink fills the engraved parts of the copper plate.

 

4. Ink scraping: The ink-coated copper plate uses a tool called the Doctor Blade to remove the ink on the surface. Through this process, ink is removed from the non-engraved parts and ink remains only in the engraved parts.

 

5. Printing: The copper plate with applied ink is quickly brought into contact with the paper to deliver the printed image. At this point, the copper plate exerts a very high pressure on the paper.

 

6. Winding: Finally, the film passes through the dryer so that the ink is completely dried. At this time, the solvent evaporates, and afterwards the film is wound up to become the finished print.

 

Thus, gravure printing goes through various stages and each stage plays an important role in print quality.

 

Flexographic Printing

 

Flexographic printing goes through a slightly different process than gravure printing. It mainly consists of the following steps.

 

1. Making a printing plate: Flexographic printing uses a flexible rubber or plastic printing plate. The design to be printed is engraved on this flexible printing plate.

 

2. Ink application: Once the printing plate is ready, the ink of the color to be printed is applied to the printing plate. The ink condenses in the grooves of the Anilox roll and is then transferred to the convex resin plate with the pattern.

 

3. Ink scraping: The ink application process in flexographic printing is different from that in gravure printing. The ink applied to the printing plate is removed using another roller, not a scraper, so that only the engraved parts remain with ink.

 

4. Printing: The convex resin plate with applied ink is brought into contact with the film to deliver the printed image. At this point, the printing plate applies pressure to the paper.

 

5. Drying: Finally, the paper passes through the dryer so that the ink is completely dried. Afterwards, the paper is wound up to become the finished print. Compared to gravure printing, flexographic printing shows differences in the material of the printing plate and the method of ink scraping, etc. These differences affect the characteristics and quality of the products produced by each printing method.

 

Differences in Printing Techniques

 

Gravure and flexographic printing each have their characteristics. The core differences between them are as follows.

 

1. Ink application amount: Gravure printing applies ink through deep engraving, so it has a large amount of ink application. This provides a higher color darkness and better image quality, but it may take longer to dry. On the other hand, flexographic printing applies ink to the surface, so the amount of ink application is small. This allows for a faster drying time, but the color darkness may not be as high as gravure printing.

 

2. Making and reusing a printing plate: The printing plate for gravure printing must be made for each design, and because it is a copper plate, it is quite expensive. Also, a new printing plate is needed if the design changes. On the other hand, the printing plate for flexographic printing is made of flexible rubber or plastic, so the cost is relatively low. Also, design changes are easier.

 

3. Printing speed: Gravure printing provides high print quality but has a slow printing speed. This is because it requires more drying time due to the large amount of ink application. Flexographic printing has a smaller amount of ink application and a shorter drying time, so the printing speed is faster.

 

4. Environmental suitability: Flexographic printing has the advantage of being able to use water-based inks and print in an environmentally friendly manner. On the other hand, gravure printing often uses solvent-based inks, which can put a greater burden on the environment.

 

Conclusion

 

We have looked at the printing methods of packaging paper - gravure printing, and flexographic printing. Flexography and gravure printing are two major printing technologies commonly used in graphic design and commercial printing. Flexographic printing is a printing technique using flexible plates made of rubber or plastic, mainly used for packaging paper, labels, shopping bags, etc. It has the advantages of fast printing speed, being suitable for mass production, and being usable with various inks and materials.

 

Gravure printing is a printing technique that directly engraves the image onto a metal plate and applies ink. This technique provides high-resolution prints and is used especially when clear images are required in magazines, catalogs, packaging paper, etc. The biggest difference between these two printing techniques is the material of the plate used and the way ink is applied during the printing process.

 

Flexographic printing uses a flexible plate, and ink is applied on the surface of the plate, while gravure printing uses an engraved metal plate, and ink fills the engraved parts. However, what's important here is the potential risk these printing techniques can expose to consumers when used in food packaging. Printing inks can directly touch food or indirectly affect it, and chemicals contained in the ink can migrate to the food. This problem can occur more seriously especially in plastic packaging or labels. Therefore, the need for eco-friendly printing techniques is being raised. Eco-friendly printing techniques focus on using materials that do not harm the environment, minimizing waste generated during the printing process, and improving energy efficiency. Also, it's necessary to use eco-friendly packaging materials and printing inks considering food safety.

 

In conclusion, while both flexographic and gravure printing techniques have their own advantages, considerations for consumer health and environmental protection are needed in food packaging paper printing. It is essential to develop and apply eco-friendly printing materials and techniques for this, and this can be said to be an important part that suggests the future direction of the printing industry.

"Gravure printing and flexographic printing require quite large equipment."