by Cassandra Balentine
Part two of two
While digital printing technology is advancing to print to almost any surface, inks sometimes require help to ensure proper adhesion.
“Adhesion promoters, or primers, become an essential part of the printing workflow by directly improving adhesion and the overall quality of the finished product,” offers Chase Pender, marketing manager, Supply 55.
In part one of our two-part series on primers we looked at the primary purposes these solutions serve, as well as added benefits, application methods, and specific versus all-in-one options. In part two, we discuss primers on the market and pricing considerations.
Surface Characteristics
First, it is essential to understand what characteristics of a surface lead to the need for a primer.
The key characteristic for the substrates requiring a primer is a low surface energy. The primer attempts to correct this by raising the energy level of the substrate to meet that of the ink, explains Jayson French, operations, Boston Industrial Solutions.
The dyne level of a substrate, or the measure of surface energy and the absorption characteristics make primers necessary. “The higher the dyne level of a surface, the better the adhesion of the ink,“ offers Jim Lambert, VP, digital division, INX Digital.
Dr. Arnd Schimanski, managing director, SURA Instruments GmbH, notes that the surface chemistry and missing functional groups on these inorganic substrates make primers essential for UV digital printing.
“Stainless steel, glass, and ceramic are all products that are to remain clean and stand up to stains, water, dirt, etc.,” says Michael Perrelli, marketing director, Innovative Digital Systems (IDS). “Those are the qualities that make them tough to print to. There isn’t enough ‘bite or tooth’ for the ink to stick well on these surfaces so primers or flame treatment is needed to accomplish the goal.”
“Basically the use of primers is a nuisance that is compensated with the enhanced in adhesion that is achieved by using them. Primers are used specially for substrates with very low surface energy, such as glass or metal,” says Martínez.
Priming Options
Several vendors offer primers or adhesion promoters to help aid in the adhesion of inks on low surface energy materials or objects.
Afford Inks offers its 52.800, 52.826, 29.840, and 29.841. The 52.800 primer is specially developed for difficult plastics including polyolefins, acrylics, and bakelite.
52.826 is a super primer for glass and metal applications. “A very thin layer will provide enough adhesion,” says Pedro J. Martínez, CEO, Afford Inks.
29.840 is an all-in-one solution, with good performance on plastics, metal, and glass.
29.841 is a highly transparent primer specially developed for glass printing.
French says the key differentiator for Boston Industrial Solutions’ primers is that they are developed with sustainability and effectiveness in mind. “They smell good and dry fast. A primed product can be printed several days and even weeks after priming. All these primers once used, leave a clear, non-detectable coating on the substrate. This feature reduces the need to clean the substrate after printing.”
Boston Industrial Solutions Primers include solutions for plastic and rubber substrates—Natron PP Primer; glass/ceramics—Natron G1 Glass primer; and metal and alloys—Natron M87 Primer.
French explains that Boston Industrial Solutions’ Natron G1 Primer and the Natron M87 Stainless Steel alter the molecular structure of the substrate to be printed to enable the UV inkjet inks to adhere to the substrate during inkjet printing. “These primers also help to create a strong link between the ink and the substrate. They improve ink surface tension and ink bonding,” he shares.
IDS offers its PYROBOND 4 GL and PYROTRACK systems, which provide flame and Pyrosil treatment in addition to a range of hand applied primers. “Whether you’re decorating glass and stainless-steel drinkware (PYROBOND 4 GL) or flat ceramic tiles and industrials tools (PYROTRACK), these systems work in conjunction with our UV printers and many other printers in the market. Easy to use and easy to implement in many printing processes, the IDS solutions are trusted by decorators of all sizes when they look to achieve optimal adhesion on typically hard-to-print products,” says Perrelli.
IRIS Glass Primer is specially designed to optimize the adhesion of UV inkjet inks on glass but Stefan Fiedler, owner, IRIS GLASS PRIMER, also sees an improvement on glazed ceramics and certain metals. It is 100 percent transparent and crystal-clear, minimal odor, non-hazardous, and does not need to be labeled, enables easy shipping, dries at room temperature, is a one-component system, presents ease of use, and is compatible with all UV inkjet systems, including LED and mercury vapor lamps.
Supply 55, Inc. offers its AP3155 primer, which is engineered for use with a variety of hard-to-print substrates including, glass, metal, aluminum, acrylics, granite, ceramics, and polycarbonates. AP3155 is an adhesion promoter for use with UV and LED curable inks when printing on glass, metal, aluminum, acrylics, granite, ceramics, polycarbonate, and other hard-to-print substrates. AP3155 is suitable for both interior and exterior applications.
Pender says AP2155 is an adhesion promoter. It is an anti-static and cleaner for use with UV and LED curable inks when printing on plastic substrates; coroplast, polystyrene, PVC, and HDPE. AP2155 also eliminates fingerprints from the printed surface area.
SURA Instruments GmbH’s SURALink 011 priming solution is designed for UV digital printing on ceramic, glass, and metals. By combination with Pyrosil pretreatment, a long-term stable adhesion is generated that withstands different stress tests up to an autoclave test, according to Schimanski.
Primer Pricing
Of course, when adding anything to the print production mix, costs are a consideration.
When it comes to primers, prices vary greatly. They are typically sold by the bottle or cartridge. “The investment is easily justified as it is a necessary step in selling a viable printed product. I urge folks to look at it like they look at ink. You need the primer or you can’t provide what customers expect,” says Perrelli.
French says primer investment are justified by cost per square feet. For example, one liter of Natron primer irrespective of the substrate yields is > 1,000 square feet per liter (10,763 square foot per liter).
The cost of primer strongly depends on the volume of printed areas. “For small areas cost of primer can reach 1 €/m² for a complete printed area. Larger volumes will reduce the costs significantly. Primers are sold in different canister sizes. Investment for spray applications are relatively low,” says Schimanski.
Martínez points out that primers are sold in different formats, from wet wipes to sprays or liquid bottles. Other than the cost per ml, its importance is on the value that they provide. “The application of a primer—which for example, could be one USD per square meter—could lead printing on substrates such as glass or metal, which brings added value.”
Primers for industrial high-volume applications like packaging are usually supplied in much larger containers, says Lambert “They are also less expensive than the digital inks themselves. The investment is easily justified because of the performance characteristics after a primer has been applied,” he shares.
Promoting Adhesion
Primers help ensure a surface is ready to accept ink. Proper adhesion between ink and substrate is essential when it comes to the quality and durability of a printed surface. Primers offer a solution for hard- to-print to surfaces.
Read part one of this series, Prepping for Print.
Sep2021, Industrial Print Magazine
