by Cassandra Balentine
Plastics are a cost-effective medium for promotional items. Technology advancements enable digital, direct to object (DTO) printing to many plastic substrates. The inherent benefits of digital allow for cost-effective short runs that support as little as pieces of one.
Manufacturers look for ways to increase product customization. “Digital DTO printing allows for a nearly limitless way to stand apart from competitors,” says Maxie Gardner, communications specialist, LSINC.
Driving DTO
Many advancements make digital, DTO printing to plastics attractive compared with more traditional methods of plastics decorating.
Susan Cox, CEO, LogoJET, lists improved adhesion and durability, high resolution and full-color capabilities, sustainable and eco-friendly materials, and integration with laser engraving equipment as factors leading to increased interest in DTO printing to plastics.
Further, the ability to combine laser cutting and UV printing on plastics opens up limitless product creation possibilities. “This integration allows for the crafting of intricate designs and personalized items, appealing to a range of industries and consumer preferences,” shares Cox.
Increasing automation in plastic printing is another trend, which William J. White, VP of global sales, Apex Machine Company, says addresses the challenge of labor scarcity. Some of these machines successfully run with limited manpower.
Quality is another consideration in which recent technological advancements have addressed DTO printing to plastics. Jay Larsen, GM/director of R&D, digital inkjet printing solutions, INX International Ink Co., says the availability of smaller printheads capable of printing closer to product features is one trend influencing the adoption rate of direct-to-plastic shapes printing.
Dave Hawkes, product manager, UV desktop printers, Roland DGA Corporation, feels that one of the universal benefits of UV printing is that it immediately improves the perceived value to the consumer. “‘Decoration,’ in the way of personalization, logos, graphics, art, texture, and color modification, immediately increases the value and appeal to the customer. One of the key benefits of plastic technology is being able to mold it into any shape you can imagine. While that’s a plus when it comes to the versatility of plastics, it can make life a lot more difficult for those who want to print on this material. The advent of UV printing has helped a lot by making it possible to print directly on just about anything, including curved, contoured, and cylindrical plastic objects.”
Innovations in printing technology make it possible to produce vivid, high-resolution images. “This expansion in printing capabilities has stimulated increased demand from the online gifting, wedding, and artist markets, as it allows for the creation of highly detailed and colorful products,” comments Cox.
“For most operators, DTO or direct to package printing yields a higher end look when compared to traditional labeling,” agrees Michael Perrelli, marketing and sales director, Innovative Digital Systems.
The availability of advanced motion systems and robotics capable of presenting the product in the correct orientation for quality printing is another advancement positively impacting DTO plastics printing, according to Larsen.
As is the availability of advance print modes to compensate for variations in product distances and motion in relation to the printhead, shares Larsen.
The continued development of inks and surface treatments help promote better adhesion and durability on plastics.
“Technological advancements in ink formulations have significantly enhanced their adhesion to plastic surfaces, minimizing wear and tear. Certain acrylic materials, for instance, come with a specialized coating to boost adhesion when using the UV direct print process. Although this might slightly increase costs, it ensures long-term durability, which enhances customer confidence,” explains Cox.
As a Medium
Benefits of utilizing plastic as a DTO printing medium include versatility, durability, and cost efficiency.
With a range of substrates available, Hugo Gonzalez, senior segment specialist, industrial printing, Mimaki USA, Inc., says it is always likely to find a plastic that works well for both the application and printing.
Plastics are compatible with a range of products and shapes, are resistant to moisture and wear, and cost effective for high-volume production, offers Cox.
“Plastics are durable and allow for a multitude of applications,” agrees Michael Litardo, marketing manager, Mutoh America, Inc. He points out that many plastics have excellent adhesion with UV LED inks, which can be improved by adhesion promoters.
White notes that plastic comes in a variety of types, thicknesses, and finishes, offering greater flexibility in choosing the most appropriate material for the desired application. “This versatility allows for printing on rigid signs, flexible packaging, and even contoured surfaces.”
Compared to paper or other traditional printing materials, plastic can withstand tougher conditions. “It’s generally more resistant to tearing, water damage, fading, and UV exposure, making it suitable for outdoor applications, signage, and products requiring longer life spans,” adds White.
Larsen says plastics are typically non-porous so they print uniformly and with higher quality than on porous surfaces.
If it comes down to cost, White points out that in most cases, printing directly on plastic can be more cost effective than traditional methods. “This is because it eliminates the need for additional materials, like adhesives or labels. Additionally, the durability of the plastic can reduce the need for reprints due to damage.”
Industry Options
Plastics are everywhere and often require decoration, notes Larsen.
Hawkes adds that short-run production for a variety of industries provides many opportunities for DTO printing onto plastics. “Manufacturers can brand and differentiate the production of such items to reach additional markets affordably and effectively.”
“Countless DTO printing applications can be produced using plastics as a substrate, but two application types that stand out are personalization and promotional branding,” shares Gonzalez. One example is a print service provider (PSP) that prints its customers’ photographs onto acrylic puzzles, personalized awards, and even personalized signage. Other PSPs dedicate their work to producing promotional branding. “They can quickly print on trays of plastic items such as pens, badges, cellphone covers, water bottles, and cups.”
The promotional products sector dominates the customization and logo market, leveraging plastics for items like keychains, pens, and various accessories. “These products provide excellent surfaces for applying vibrant, full-color UV prints directly, making them ideal for brand promotion,” says Cox.
Award and promotion shops are another avenue. “ADA braille printers and industrial manufacturers are all using a variety of plastics,” says Litardo. “The profit margin on ADA braille signs is huge. The profit from ADA braille can easily pay for a printer in a short period of time.”
The demand for premium architectural signage is also on the rise, with a particular interest in utilizing acrylic and other plastics that can be laser engraved or routed. “This technique is widely adopted for creating sophisticated indoor signage for offices, walls, and other spaces. The incorporation of UV printing on these materials allows for the addition of vibrant colors and intricate designs, further elevating the aesthetic and functional appeal of architectural environments. These advancements offer architects and designers new opportunities to integrate branding and directional signage seamlessly into their projects, merging functionality with high-end design aesthetics,” offers Cox.
In consumer products, Larsen sees two areas where digital inkjet decoration helps. “One is for products like cosmetics, with a multitude of color variations on the same label. The second is for mass produced products where the inline capabilities of digital inkjet can save considerable money in the logistics of procuring, managing, storing, and applying labels.”
“Food, beverage, cosmetic, and medical market players are placing more value on branding of containers and DTO can be a promising method for them,” notes Juan Kim, CEO, Valloy Incorporated.
Consumer electronics is another industry with potential. It frequently uses plastics such as ABS and polycarbonate for casings, panels, and accessories. “These materials are particularly suited for UV inks due to their inherent surface energy, facilitating strong adhesion and lasting prints,” agrees Cox.
Gonzalez agrees that this space is growing for DTO for plastics due to increasing demand for personalized electronic accessories such as phone cases and laptop covers.
Moving into more industrial applications, Larsen points out that high-volume industrial containers like paint buckets and caulk tubes can be short runs or custom colors where the benefits of digital inkjet production is important.
Kim sees industrial substrate decoration on rigid or flexible material as a huge market. “Ceramic tile or artificial marbles are often produced by DTO now.”
The automotive industry utilizes DTO printing on plastics for customizing interiors, such as dashboard panels, trim pieces, and gauge dials. “The opacity lends itself to selectively covering LED panels,” shares Gonzalez.
Cox sees a noticeable shift in the automotive industry from traditional silk screening to digital direct printing for component and part labeling. “This transition allows for more dynamic color options and intricate designs, enhancing the aesthetic appeal and functionality of automotive parts.”
There is also a place for this technology in healthcare and medical devices. “DTO printing on plastics has generated some interest in items that require regular sanitation such as hospital signage and some medical instruments,” notes Gonzalez.
And of course, we can’t forget packaging. “The packaging sector is increasingly opting for direct printing on containers and closures over traditional labels or decals. DTO printing offers a perceived higher value and aesthetic appeal, allowing brands to stand out on the shelves by integrating intricate designs and vibrant colors directly onto their packaging,” says Cox.
Kim agrees, adding that brand owners look for enhanced levels of brand presentation by in-house process. “In-house label printing and cutting can be an option but it needs a separate process line and there are more regulations to limit label size, substrate type, and removability, due to environment and recycling issues. Direct printing covers less coverage on the plastic containers and it is suitable to put in the middle of a production line.”
Limiting Factors
As a maturing technology, there are still many challenges to direct printing on plastics. Surface preparation is essential to improving adhesion properties on certain plastics.
Properly preparing the plastic surface for printing is crucial. This involves several steps, including ensuring the surface is clean of fingerprints and dust, reducing static electricity that can attract dust, and applying treatments to enhance adhesion. “Removing protective liners from materials like acrylic can also introduce static, complicating the preparation process,” shares Cox.
Adhesion—and the resulting quality—is a top limitation for some plastics. “Not all plastics will provide the necessary adhesion to produce sellable output. There are also plastics that will not handle well during the curing process,” comments Litardo.
Adhesion promoters are designed to significantly improve the ink’s ability to adhere to a variety of plastics.
Employing methods like corona and plasma treatments enhance the plastic’s surface energy, promoting better ink adhesion. These treatments are crucial for preparing plastics, especially those known for challenging ink adherence,” notes Cox.
“Achieving strong ink adhesion on certain plastics remains a significant hurdle,” admits Cox. Materials like polyethylene, polypropylene, and nylon, known for their flexibility and cost effectiveness, present challenges for UV printing without extensive pretreatment. “These plastics often require additional processes such as plasma treatment, the use of adhesion promoters, or flame treatments to prepare the surface for printing. This necessity adds steps to the production process, potentially increasing costs and complexity.”
Gonzalez agrees, noting that a primary limitation is the surface dyne level of certain plastics, which may require additional priming or surface treatment processes to ensure proper adhesion. “Some plastics are specifically designed to resist degradation or to be stain resistant—these properties usually reduce the surface tension, which reduces the adhesion properties. Another common challenge to DTO is that the print surface isn’t always flat. Most printers have tight tolerances on the ability to print clearly on uneven surfaces, so prints can end up having different ranges of print quality.”
James Bullington, CTO, LSINC, adds that flexible plastics may require a flexible ink. “Squeeze bottles and flexible cups suffer from cracking and flaking if the layer thickness for a semi-rigid ink is too thick.”
Care must be taken with the jetting distance and static on the surface of the media. “Stadium cups often have a lip that increases the jetting distance from the head to the surface; as a result, they are more susceptible to image defects caused by static on the surface of the media. Plastics often carry a surface charge that will pull overspray onto the surface outside the target print area. Neutralizing the charge becomes essential,” says Bullington.
Cox points out that the diversity in plastic materials means that not all are compatible with DTO inkjet printing techniques. “The surface energy and texture of the plastic play critical roles in how well the ink adheres and the quality of the final print. Plastics with low surface energy or highly textured surfaces may not hold ink as well, leading to issues with print durability and fidelity. This limitation necessitates a careful selection of materials based on their suitability for the intended printing process, which can sometimes restrict design and material options.”
Media manufacturers are increasingly knowledgeable about the demands of UV digital printing and are thus producing materials optimized for these processes. “For instance, cast acrylics are recognized for their superior adhesion to UV digital prints compared to extruded varieties, demonstrating the importance of material selection in achieving high-quality prints,” suggests Cox.
Print durability is another potential challenge, which Cox says lies in producing prints that are not only vibrant but also durable enough to resist fading, scratching, and peeling over time. “Solutions like applying a clear gloss overprint or using laminates can significantly enhance the longevity of prints, especially for applications exposed to sunlight. However, these solutions increase overall production costs and time.”
Hawkes admits that price is an issue when it comes to equipment. “Combining improved price positioning with performance is the strategic objectives of manufacturers.”
It is important to find the “right printing recipe” to reach the desired adhesion, durability, chemical resistance, quality, printable area, color gait, and control required by the project, asserts Larsen.
Kim notes that it is important to provide a flexible and modular DTO solution, which can be adopted to any process using conveyer, roll to roll, or sheetfed.
Hawkes sees a challenge in terms of developing ways to make DTO printing to plastics—and the output—more environmentally sustainable, as well as improving the technology to further simplify the process and increase the cost effectiveness.
Bullington adds that plastics have their place based on durability and cost; however, he sees a strong push across the globe to eliminate single-use plastics. “The legislative landscape could be the determining factor as to whether single use plastics are banned, and more durable alternatives take their place.”
Future of DTO
As DTO printing to plastics continues to advance, the future is full of potential.
“We’ll likely see improvements in print quality, speed, the range of materials that can be printed, and the materials that make up the ink to enable a wider range of uses,” states Gonzalez.
Kim points out that the technology is not yet fully mature, due in part to the fact that there are so many different use cases based on an object’s shape, flexibility, material property, and recyclability.
“Direct inkjet printing on plastics is in the early stages of adoption. Machine builders, ink manufacturers, surface preparation vendors, and others are all working hard to improve all aspects of direct to plastic printing to bring it further into the mainstream,” adds Larsen.
Automation is a key part of this and will continue. “Automation has entered the digital process where robotic arms can load/unload machines efficiently,” notes Perrelli.
Litardo sees continued adoption, with new and improved versions of plastic materials introduced all of the time. “I believe end users will continue to find new and exciting ways to use these materials.”
The cost and waste associated with technologies like labeling as well as the quality of print consistently increasing, will move a lot more products from labels to printing, predicts White.
Cox says the future of DTO printing on plastics is expected to see significant growth and evolution. This optimism is rooted in several key factors—innovations in materials science and sustainability, demand for customization, advances in printing technology, and integration of decorative techniques.
Printing to Plastics
Plastics come in many forms, which brings endless possibilities along with some limitations when it comes to printed decoration. We look forward to covering the continued opportunity in DTO printing to plastics as technology advances to ensure better adhesion, print durability, and quality.
Jul2024, DPS Magazine
