Hey there! If you’re looking to print on plastic film substrates with flexo printing, you’re in the right place.
Plastic films are tricky to work with because they’re different from other materials, but flexo printing can give you awesome results if you know what to do.
In this guide, I’ll walk you through the steps to get high-quality prints on plastic film substrates, save time, and keep your costs low.
Let’s get started!
Why Flexo Printing Works Great for Plastic Film Substrates
First, let’s talk about why flexo printing is a smart choice for printing on plastic film substrates.
Flexo printing is a fast and easy way to print on materials like plastic films, which are often used for packaging stuff like food, clothes, or even labels. These films—like PET, BOPP, or PVC—are strong, water-resistant, and budget-friendly, which makes them super popular.
With flexo printing, you use a special roller called an anilox roller to put ink on a printing plate. Then, the plate transfers the ink onto the plastic film as it moves through the machine.
This method is great because it can print at high speeds—like up to 500 meters per minute—meaning you can make a lot of prints quickly without waiting around.
Plus, it works well for getting vibrant, clear images on plastic film substrates, which is exactly what you want for high-quality prints.
Key Factors for Flexo Printing on Plastic Film Substrates
To get the best results when you print on plastic film substrates with flexo printing, you need to think about a few things. Here’s what to keep in mind:
Surface Tension: Make Sure the Ink Sticks
Surface tension is how the ink behaves on the plastic film—it’s like how water beads up on a shiny surface. For the ink to stick well, its surface tension needs to be lower than the printing plate’s. A good rule is to use ink with a surface tension that’s 10 dynes lower than the film’s surface energy.
For example, if your plastic film has a surface energy of 40 dynes/cm, pick an ink with a surface tension of 30 dynes/cm or less. This helps the ink spread evenly and stick properly, so your prints look smooth and clear.
How to Optimize:
- Use ink with a surface tension 10 dynes lower than the film’s surface energy.
- Adjust ink with additives like alcohol or use treated films to improve compatibility.
Surface Energy: Help the Ink Stay Put
Surface energy is how much “stickiness” the plastic film has. If the surface energy is too low, the ink won’t spread well, and your prints might look blurry or spotty. Most plastic films, like PET, start with a low surface energy—around 30 dynes/cm—but you can raise it to 42-46 dynes/cm with treatments like corona discharge.
This makes the film ready for ink to stick better, so you get high-quality prints on plastic film substrates.
Wettability: Get Smooth Coverage
Wettability is the ink’s ability to spread evenly on the substrate. Good wettability ensures smooth coverage and prevents pinholes or blurry prints.
Optimization Tips:
- Match the ink to the substrate’s surface energy.
- Use highly polar plates and high-energy substrates for better interaction.
Ink Selection: Pick the Right Ink
Plastic films require ink with low surface tension and strong adhesion. Water-based, solvent-based, or UV inks are commonly used, offering quick drying and compatibility with high-speed printing.
Tip: Test a small batch of prints first to make sure the ink sticks well and the colors pop.
Distortion Control: Keep Images Sharp
Sometimes, flexo printing can stretch or distort your images because the printing plates are flexible. To avoid this, use high-quality elastomer sleeves instead of regular plates. These sleeves are made to stay the same size—100% accurate—so your prints come out sharp and clear.
They’re also tougher and can handle more printing jobs without wearing out.
Time and Cost Efficiency
Flexo presses are known for high-speed production. Choosing the right equipment and materials can reduce downtime and save costs while maintaining efficiency.
Surface Treatment Techniques for Plastic Film
Plastic films often need surface treatments to improve ink adhesion and print quality. Here are the most common methods:
Corona Treatment
This cost-effective method uses electrical discharge to polarize the film’s surface, increasing its energy and compatibility with ink.
Chemical Treatment
Films are treated with chemical agents to alter their surface structure, enhancing compatibility with inks.
Photochemical Treatment
Using UV or laser light, this method improves the film’s polarity and adhesion properties, resulting in better ink performance.
These techniques minimize issues like poor adhesion or unclear prints, delivering higher-quality results.
How to Plan Your Print Sequence for Plastic Film
The order in which you print can make a big difference in your results. Here’s how to do it right when you print on plastic film substrates with flexo printing:
Surface Printing:
Start with a layer of white ink as a base. This makes the colors on top—like red, blue, or yellow—look brighter and more vibrant. It’s like painting a wall white before adding a fun color—it just makes everything pop.
Reverse Printing:
In this method, you print on the inside of the film, so the image is protected by the film itself. This is great for things like food packaging because it keeps the print safe from scratches or water.
For example, snack bags often use reverse printing to keep the design looking good even after being handled a lot.
Tip: Pick the right method based on what you’re making—surface printing for bright labels, reverse printing for tough packaging.
Comprehensive Tips for Efficient Printing on Plastic Film
To achieve outstanding results with flexo printing on plastic film, consider these strategies:
- Select inks and plates that ensure excellent transfer and adhesion.
- Treat the film’s surface to enhance printability.
- Use precision-engineered elastomer sleeves to reduce distortion and increase productivity.
- Optimize the print sequence and ink application to achieve vibrant, clear images.
Now you know how to print on plastic film substrates with flexo printing and get awesome results. By picking the right ink, treating your film, and planning your print sequence, you can make vibrant, durable prints that your customers will love.
Plus, flexo printing is fast and cost-effective, so you can save money while growing your business.
Need help getting started?
Contact us for a free guide on flexo printing, or check out our blog for more tips on printing on plastic film substrates. Let’s make your prints the best they can be!
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