Types of Flexographic Inks and How to Select the Right One

Ink is a vital element of the Flexographic printing process, giving colour to a wide range of substrates. But when it comes to selecting the right inks for Flexo printing, requires nuanced knowledge of Flexographic ink and its types. If you are ready the learn the nuanced knowledge required for selecting the right ink, you are at the right spot. This comprehensive blog post covers the basics of Flexographic inks, types, and factors that influence the selection process. We have shared some extra tips to ease your selection process at the end. So, keep reading!

A] What Are Flexographic Inks?

Flexographic inks are specialised inks used in the flexographic printing process to print on flexible materials, such as labels, packaging, and other speciality items. These inks are designed to provide workability with a variety of materials, including paper, cardboard, metal films, and foil. Flexographic inks consist of pigments, binders, solvents, and additives. In addition, most of the flexographic inks are known for their eco-friendliness as they emit low VOC (Volatile Organic Compounds) emissions, making them safe for use in food packaging. 

Now, let’s explore the classification of flexographic links:

B] Types of Flexographic Inks

1. Water-Based Inks

Water-based inks, also known as aqueous inks, are a type of flexographic ink that uses water as a primary solvent and carries pigments or dyes. Due to the water-based solvent, they dry through evaporation, leaving pigments and binder on the substrate. Water-based inks are used to print corrugated boxes, paper bags, tissue products, napkins, and folding cartons. They offer several advantages, including eco-friendliness, cost-effectiveness, and low VOC emissions. However, they may not be suited for non-absorbent surfaces due to their poor adhesion capability.

2. Solvent-Based Inks

Solvent-based inks are a type of flexographic ink that uses organic solvents (e.g., alcohols, esters) to carry the pigments. The organic solvents used in the solvent-based inks are volatile, which facilitates faster drying time. They are known for their excellent adhesion, quick drying, and durability on flexible substrates. Solvent-based inks are widely used for printing plastic films (PE, PP), aluminum foils, snack packaging, and shrink sleeves. However, they pose some limitations in terms of high VOC emissions and flammability concerns. 

3. UV-Curable Inks

UV-curable inks are a highly popular Flexographic ink that contains photoinitiators that react with UV light and initiate the polymerisation process. Due to UV-cureability, it offers instant curing, excellent colour strength, and chemical resistance. UV-curable inks are widely used in pressure-sensitive labels, shrink sleeves, folding cartons, and high-end retail packaging. However, they have some limitations, such as higher cost, potential for skin irritation, and requirement for UV lamps. 

4. Electron Beam (EB) Inks

Electron beam (EB) inks are similar to UV inks, but cured through electron beam instead of UV light. They use a beam of high-energy electrons to initiate chemical reactions within the ink formulation. EB inks are known for their low odour, rapid curing, and compliance with food safety regulations. However, EB links require a high initial investment in electron beam curing equipment.

C] How to Select Flexographic Ink: Factors to Consider

1. Substrate Compatibility

Before selecting the right Flexographic ink, ensure that it is compatible with the substrate on which the ink is to be printed. It allows you to achieve optimal adhesion, print quality, and overall performance. Water-based inks are a good choice for porous substrates, such as paper and cardboard. Solvent-based and UV-curable inks are the best choice for non-porous surfaces, such as plastic films and foil.

2. Regulatory & Safety Needs

Assessing regulatory compliance and safety needs is paramount to restricting the use of harmful inks on food-grade packaging and labels. For food-grade packaging, it is essential to select non-toxic ink to ensure safety and compliance.

3. Performance Requirements

Flexographic inks must meet several performance requirements before selecting them. The requirements include resistance to water, chemicals, abrasion, or UV. In addition, ink should have high colour intensity, sharpness, and rapid drying time, among others.

4. Print Quality Expectations

Deciding print quality expectations and choosing the right colour based on the expectations ensures you get the intended outcome. It also ensures colour accuracy and consistency, durability, and longevity.

5. Press and Drying Capabilities

Assessing the press and drying capabilities of ink is crucial, as they can impact the print quality, efficiency, and even overall production. Fast-drying inks dry fast and prevent the inks from spreading and smearing. In addition, ink should also be compatible with existing drying systems, such as air, UV, and EB. On the other hand, choosing the ink based on the press capability ensures ink matches the printing machine.

D] Extra Tips to Choose the Right Flexo Ink

Conduct print trials to test ink-substrate compatibility before full-scale production. Consider total costs, including drying methods, ink waste, and environmental compliance, not just the ink price. Consult with flexographic printing machinery’s ink suppliers for tailored or hybrid ink solutions that match your specific print conditions and performance needs, ensuring both quality and efficiency in your flexographic printing process.

Conclusion

Flexographic inks are the essential part of the flexographic printing process. It enables facilities to produce large print runs with quality and durability. Follow the suggested steps to choose the right ink for your upcoming printing project. 

NBG Printographic Pvt. Ltd is one of the top printing machinery manufacturers in India, offering cost-effective, durable, and high-quality Flexo printing machines. Our printing solutions are designed to provide high-quality and vivid printing outputs. Contact us today!

FAQs

What is flexographic printing ink?

Flexographic printing ink is a fast-drying, low-viscosity ink used in flexographic printing. These inks are designed to transfer efficiently from flexible printing plates to various substrates, including paper, plastic, and foil.

What are the main types of inks used in flexographic printing?

The main types of flexographic inks are water-based, solvent-based, and UV-curable inks. Water-based inks are eco-friendly and suitable for porous surfaces. Solvent-based inks dry quickly and adhere well to non-porous materials. UV-curable inks offer high-quality prints and instant curing when exposed to UV light.

How do I choose the right type of ink for flexo printing?

To choose the right ink, consider the substrate type, printing speed, environmental regulations, and end-use requirements like resistance to moisture or abrasion. For example, solvent-based inks work better on films, while water-based inks are preferred for paper.

How does ink formulation impact print quality and adhesion?

Ink formulation affects print sharpness, color strength, drying time, and adhesion. Proper formulation ensures minimal smudging, vibrant colours, and durable prints, enhancing both visual appeal and product longevity.