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Overcoming the challenges of printing on novel substrates
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There was a time when printers only had to concern themselves with getting ink to look good on paper. Those days are over as words and images have to be applied to a wide range of materials, including metals and plastics. Unlike printing on paper, printing on metals and plastics can require the preparation of the surface to accept the inks. In some cases, primers have been used; in others, such as with printing on metals, oils must be chemically removed from the surface. As printing technology has evolved, inks have been formulated with special solvents that enable them to be fluid enough to flow onto the surface, yet evaporate to leave a sharp image. To create vibrant, long-lasting colors, heavy metals are sometimes incorporated into the inks. |
| Openair® plasma improves ink adhesion on commonly used substrates, including plastic laminates as well as on other more unusual items such as toys and electrical components. |
Making ink stick
Openair® plasma can eliminate many of the problems of getting ink to stick, particularly on difficult surfaces like polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), UV coated, film coated and metalized surfaces. By quickly treating the surface with a plasma jet prior to printing, the ink will flow onto the surface more evenly. When the ink dries it performs better, looking brighter and adhering better. Of most significance, the inks can be reformulated so they do not contain harmful solvents and heavy metals can be eliminated.
On metals, Openair® plasma removes surface oils that cause adhesion problems, and can replace costly and environmentally hazardous solvent cleaning processes.
On plastics, Openair® plasma not only removes mold release agents, slip modifiers, plasticizers and other contaminants from the surface, but also functionalizes it, creating chemically reactive sites that bond to the ink. The wettability of the surface increases to the extent that water-based and food grade inks can replace solvent-based inks. In addition, Openair® plasma removes dust from the surface as well as the static that attracts dust, thus eliminating a common cause of printing defects.
Openair® plasma can be used to pre-treat surfaces for the following printing processes:
- Pad printing
- Screen printing
- Inkjet printing
- Thermal transfer printing
- Flexo printing
- Offset printing
How Openair® plasma has helped printers
Child-friendly inks.
Toys are a special challenge for the adhesion of inks, but also for ink toxicity because young children explore their world by putting them into their mouths. One internationally recognized toy manufacturer used Openair® plasma to treat polypropylene (PP) parts and print them using a water-based food-grade ink system. |
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Bottle caps.
One soft drink manufacturer sought a way to print their logo on bottle caps, indelibly. The caps were in any case a challenge to print owing to the high level of filler. By treating the caps with Openair® plasma and printing with special inks, their logo cannot be removed. |
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Yogurt containers.
Polypropylene is an excellent material for molded cups to contain dairy products such as yogurt or ice cream. It is stronger than high-density polyethylene (HDPE) so the containers can be 30% lighter. However it is more difficult to print and cannot accept complex graphics. One customer used Openair® plasma to activate the surface, achieving high quality graphics and saving money. |
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Cartons.
Folding cartons that are UV coated or film-laminated are difficult to glue, often requiring mechanical abrasion and expensive hot melt glues. When the surface is activated with Openair® plasma, water-based coldset glues can be used, saving money and energy. |
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We are specialists in Openair¨ plasma and can improve printing applications in your specific industry.
Contact us to learn more. |
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