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How fabric coatings affect inks

September 1st, 2013 / By: / Graphics

It is no news that our world is one of rapidly changing technologies. What once was a standard practice or an expected result is not necessarily the case in fields as varied as product design to print media. The world of fabric graphics is no exception. To get to the heart of the evolving technologies surrounding the performance of ink on coated fabrics, I had an email chat with three respected sources in the field: John Lutzke of Banner Creations Inc., Minneapolis, Minn.; Stephen J. Mills, CEO of Ink Mill Corp., Sanbornton, N.H.; and Mike Plier, president of Polymeric Imaging Inc., Kansas City, Mo.

Plier emphasizes that his responses are not geared specifically to textiles and garments, but rather to the entire printing arena—industrial, commercial, POP and retail. “My answers should provide a good temperature reading of how companies like ours look at any given project. Polymer chemistry isn’t a guess, it’s science,” he says.

Here is what Lutzke, Mills and Plier had to say:

Question: Does the performance of ink change or vary when
protective coatings, such as UV inhibiting or fire retardant coatings, are applied to fabrics?

Lutzke: There may be a tonal change or color shift with some coatings. The performance may not vary much but it can be noticeable to the trained eye, and possibly high-maintenance customers. Also, there may be a bigger issue with ink systems other than dye sub. For instance, when we screen-print on fabrics there are many issues with coatings. If FR treatments are applied after printing, sometimes there is an issue. But, the quality of FR treated fabrics has improved greatly since we started purchasing treated fabrics.

Mills: It is very common to use UV inhibiting and protective coatings to extend the durability of inks. By using a good coating, the outdoor durability of a fabric can be extended and the ink’s useful life will be maximized. The effect of FR coatings both below and on top of the ink layer has been tested thoroughly, and one does not seem to affect the other. In other words, the coating has no effect on the ink performance and the ink has no effect on the FR performance.

Plier: Coatings are developed to provide specific benefits for inks that may be lacking in certain areas, i.e. water resistance, color fade, durability. Once the ink is applied and dried onto the substrate its characteristics should not change. Any coating applied over it should enhance any end requirements that the ink will not pass. Whether it is for durability, flame retardance, chemical resistance or abrasion resistance, these coating must not adversely affect the material in any way. It is our job to make sure this does not happen.

Q: Is there a “best” way to use
inks with coatings?

Lutzke: Setting up a good color management system will help identify which coatings have a pronounced effect on ink outputs. Your profile should account for each type of coated paper and fabric in use, in order to keep color fidelity where you want it.

Mills: For FR, the coating should be applied to the substrate before printing. For UV and protective coatings, the coatings should be applied after printing the ink.

Plier: Printed samples should always be tested with the coating to ensure proper flow over the ink and adhesion of the two systems. When properly formulated, these systems are designed to integrate with any given substrate. In some situations, these products are designed to run within the restrictions of any given environment and production capabilities. While we may enter a given project with a base formulation, often these solutions are not a viable option for a given production environment. In such cases, our laboratory must develop formulations that can run effectively and efficiently, i.e. water-based vs. UV vs. solvent.

Q: What guidelines should end product manufacturers—print shops and digital graphics companies—use to determine the correct ink for the job? What cautions need be observed?

Mills: Selecting inks has everything to do with the end-use application. The EPM should fully understand the application before choosing ink, or even the printing technology. It is important to have input from the technical staff, the client and the ink manufacturer. Common performance requirements that need to be known beforehand are: substrates and adhesion, color requirement, durability of the color, abrasion resistance, chemical resistance, curing/drying, coating functionality, and safety concerns (toys, packaging).

Plier: To ensure proper adhesion and other end-use specifications, ink manufacturers can pre-test coatings with printed parts supplied by their customer. In the early stages of research and product development, the inks and material selection for a job is not an accident or random choice. It is one calculated with great care and followed through to the letter. To do anything less disciplined would be a formulation for disaster. Pre-testing, data collection, and tracking are vital to successfully providing the end-user with a consistent, repeatable product.

Q: Are there any special considerations that must be taken to ensure the inks will be durable if a coating is applied after printing?

Mills: The coating should not solubilize the ink coating. This can be tested beforehand easily.

Plier: Proper testing is required to ensure that the coated parts do, in fact, pass end-use requirements. Most ink companies have technical departments that focus on application and testing. In the end, the product developed by any given lab is only as good as the information with which they were supplied. Our lab thrives on information; it is the building block on which all of our formulations are based. At Polymeric, before any project is attempted, our researchers go through an extensive interview process with the client. Questions about weatherability, chemical and solvent resistance, abrasion, washability, feel, flexibility, ease of processing, etc. are all asked. When nothing is left for interpretation and there are no blanks to fill in, our lab is ready to go to work.

Q: What can users expect in the near future with regard to improvements or trends within digital ink technology?

Plier: Now this is a loaded question for sure, especially for us. Today, Polymeric Imaging has more than 21,000 formulas in our building, most of which are custom. For us, the new and exciting menu of raw materials literally opens the door to an unlimited variety of products ranging from plastic, metals, glass, films, textiles and adhesives. Whether these products are cured by heat, UV, LED or EB (Electron beam) matters little. The sky is the limit.

Mills: The newest trend in digital ink technology is the emergence of UV-LED curing. Until a year ago, the ink technology and the available lamps were not adequate to reach the printing speeds for a realistic product. Over the past 12 months, technology has made great strides in producing a commercially viable product with a good price point. With the trend of this market segment, a UV-LED printer is now both affordable and fast enough for a small print shop. When this is coupled with the drive for higher resolution prints in the marketplace, I expect that the smaller print shops that invest in this technology will see an increase in profits from sales.The inks and coatings industry continues to make technological advances, bringing digital printing into a much wider range of applications. This innovation will allow the digital inks and coatings industry to continue to grow.

Mason Riddle is a freelance writer based in St. Paul, Minn.

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