Flexo CtP?Out of the Gates
With benefits stemming from the improved quality of digital plates, CtP for flexo is making its presence known.
by Tom Polischuk, Editor-in-Chief
WITH COMPUTER-TO-PLATE (CtP) technology for flexographic printing nearing its pre-teen years, its benefits are having a significant impact throughout the industry. These benefits are derived from the elimination of film and the on-press efficiencies stemming from improved quality plates.
Frances Cicogna, packaging segment marketing manager for Agfa, points out a major difference between the current state of CtP for flexo vs. CtP for offset. "Computer-to-offset is a direct-image process in which the plate is exposed via the laser. Computer-to-flexo uses a digital mask in which film that is pre-applied to the plate is imaged—the plate is then exposed and processed conventionally."
An array of plate options are available including digital sheet plates that can be processed using chemical-free, solvent-washout, or water washing methods; digital plates for processing 'in the round'; and digital plates that can be processed thermally.
MacDermid Printing Solutions offers a variety of photopolymer plate technologies, including traditional sheet photopolymer, digital sheet photopolymer, digital sheet photopolymer in-the-round, liquid photopolymer technology, and water-washed sheet photopolymer technology. Geoffrey Barba, director of marketing, says the company is continually developing ways to improve both the processing times for these products and the on-press performance.
He also sees the growth beginning to build with digital technology. "Digital plate technology is gaining market share," he says. "The ability to image finer dots helps improve the overall print quality of flexo."
Water-wash digital plates bring along the advantages of both digital technology and water-wash processing. Anderson & Vreeland (A&V) provides CtP systems that "process digital photopolymer plates with an aluminum-based ablative layer that washes out in plain tap water," says Paul Zeinert, product manager for A&V. Benefits include reduced drying time, reduced costs, and excellent ink transfer.
DuPont Imaging Technologies is on the leading edge of digital plate technology with its Cyrel® Digital plates. These plates are coated with a laser ablation mask (LAM) that, when imaged in a CtP engine, creates a photo mask that is in direct contact with the plate material, describes Ray Bodwell, digital marketing manager. "Once the imaging step is completed, the digital plate is processed in the same sequence of steps as an analog sheet photopolymer plate."
DuPont took a significant step in flexo CtP progress when it introduced its Digital Cyrel®FAST plates. Instead of being processed using solvents, Cyrel®FAST plates are processed thermally. "This reduces processing time and eliminates the drying step entirely, allowing a finished plate to be made in well under an hour," says Bodwell.
Plate processing equipment
Mark Vanover, Esko-Graphics' director of marketing for North America, says that the thermal technology used by the Esko-Graphics CDI (Cyrel Digital Imager) line of digital flexo platesetters, "offers a distinct advantage in that it allows for imaging of all digital flexographic plates and sleeves."
When making the move to flexo CtP, the actual digital prepress workflow doesn't differ much from the digital prepress workflow for computer-to-film analog plate production. However, when using digital flexo plates, Vanover emphasizes that users must understand the differences between analog and digital platemaking, and their influence on press. "Most changes arise from the different formation of the digital dot, with its characteristic shoulders. Dot gain on digital plates is about 50 percent less than analog, so completely new curves must be made. And, plate floor depth will be less. Esko-Graphics helps customers understand this process with our FIQ (Flexo Implementation Quality) program to insure the transition from analog to digital plates is seamless."
Northwest Flexo, a printer of high-quality tags and labels located in Lynnwood, Wash., recently installed an Esko-Graphics' CDI Spark flexo platesetter that it purchased through The Pitman Company. Using Cyrel®FAST plates, the company achieved immediate productivity improvements in its plate-processing time, which dropped by two-thirds. The plate quality improvement, however, really impressed Kevin Davis, president of Northwest Flexo. "You've got to see the quality of digital plates to believe it. In our 175 lpi process color and vignettes, we're holding dots you can barely see with a loupe." After seeing a trial print using digital plates on a four-color process cosmetic label, Davis says that the customer wanted its entire business converted to digital plates.
Creo incorporates laser diode imaging technology in its ThermoFlex® product line. It uses multi-channel laser diodes to produce from 24 to 64 beams, and uses "beam-shaping" optics to create the optimum energy profile for plate imaging, reports Bob Dalton, product manager for Creo.
He points out two key features available with the ThermoFlex line—the ThermoFlex Sleeve Option and HyperFlex™. With the Sleeve Option, trade shops, printers, or converters have the ability to image plates, film, continuous photopolymer sleeves, and digital plates mounted on sleeves, all on one device. HyperFlex is "designed to increase the capability of a flexo plate to hold fine features," says Dalton.
Converting to digital plates
When converting to digital flexo plates, package printers have the ability to ease into the new technology because traditional plate processors can be used with digitally imaged plates. "Traditional flexo plate processors can capably process thermally-imaged (laser-ablated) flexographic photopolymer flexo sheet plates," says Derek Case, worldwide business director, packaging market segment, for Kodak Polychrome Graphics (KPG).
Case points to KPG's Point Light Source System (co-branded with OLEC) as a means to transition into digital plates. The system offers improved imaging from the ability to produce dots with steeper shoulders. This improved imaging will be applicable "even after they have moved from film-based analog plate exposure to a digitally imaged computer-to-flexo plate," says Case.
No matter how a package printer transitions into digital plates, it is apparent that CtP for flexo has gotten a strong foothold. Dalton reports that Creo saw a dramatic increase in the adoption rate of flexo CtP in 2003, and he expects the trend to continue in 2004.
Although there is no direct-image CtP flexo technology viable at this time, the advantages of digital plates are being felt in the industry. This is likely to pick up steam. "There is no question that CTP technology has a huge advantage when it comes to quality vs. conventional film," says Zeinert. "This improved quality will drive the transition from computer-to-film to computer-to-plate."
Resources
Agfa www.agfa.com
BASF www.basf.com
Creo www.creo.com
DuPont www.dupont.com/cyrel
Esko-Graphics esko-graphics.com
Kodak Polychrome kpgraphics.com
MacDermid www.macdermid.com
Max Daetwyler www.daetwyler.com
Pitman www.pitman.com
Trinity Graphic trinitygraphic.com
