A New Approach

Advances in digital printing technology are the new frontier of décor printing. Bipan-Astrid, a subsidiary of the Italian industrial Gruppo Frati, has taken innovation further by applying patent pending inkjet technology to digitally print décor designs directly onto the surfaces of individual HDF flooring planks. Bipan’s new generation of flooring product, called NextFloor, is made with this revolutionary approach. The process combines specialized plank preparation and hot coating technologies with digital inkjet printing to effectively eliminate all the paper-related steps involved in manufacturing conventional laminate products including: paper production, printing décor paper, paper impregnation and the application of paper and wear layers to standard size panels. In addition to signifi cant cost savings, Bipan’s process reduces waste and environmental impact while offering unprecedented design flexibility.

Trends are like winds: they can change direction sharply and unexpectedly. Bipan’s digital direct printing process provides a cost effective means of following trends in real time. But more than that, the technology opens up new ways to market fl ooring products that were previously impossible to approach, such as custom fl ooring for special events. Every product in the NextFloor catalog (including all the AC class ranges and décor possibilities) requires the same basic materials: HDF boards, four inks, primer and proprietary hot coating developed by Kleiberit. Available designs are limited only by imagination, not by existing décor paper storage stocks. And because production time is not dependent on external suppliers’ wait times (printing rolls, printed paper) NextFloor can fulfill small runs and custom orders as quickly and efficiently as bigger jobs. In fact, the printing technology is so precise and versatile that the printer can switch between different décor designs in “zero seconds” without stopping production.

Gruppo Frati developed the digital inkjet direct printing equipment and method in partnership with Kodak, and has exclusive rights to the technology as it relates to wood-based panel application. Kleiberit adhesives developed the innovative HotCoating finishing system that uses a simplified line of Barberan machinery to apply adjustable coats of extremely flexible and durable reactive PUR to the printed HDF. The overall technology, including applications for furniture components, is promoted on the market by Dieffenbacher, which offers complete plants from panel cutting through final coating.

Preparing the Substrate

The direct décor printing process for NextFloor is a series of manufacturing steps applied to the base HDF boards. Preparing the substrate for printing is a two-step procedure. The first step applies a filler coat to a standard size HDF panel to seal and smooth the surface. This also prevents moisture migration from the HDF board to the upper layers. Next a roll coater applies the print base layer coat. Successful digital inkjet décor printing requires the print base coat to have exactly the right degree of absorbency, so that the surface accepts the ink, but the ink does not spread sideways. This receiving layer will also fix the ink after printing, protecting the image from moisture and ultraviolet light exposure. A backside coat of UV lacquer is applied with a single roll coating machine during this phase. As the panel proceeds down the line, a UV dryer cures the bottom of the panel, protecting the bottom of the finished flooring from subgrade moisture. At this point in production the panel is sliced into planks and stored in a buffer between single process phases, a necessity due to the speed differential between individual processes.

Printing the Images

The image files for digital décor printing can come from a scanner (NextFloor uses a Cruse Scanner), professional digital photo equipment or files created using specialized software. The minimum resolution for the final décor file has to be 300 dpi in a TIFF-RGB format. Proprietary software RIP creates the CMYK color separation files for the printer, which can be modified to correct small defects and sized to match plank dimensions. Quality control for image sampling and color verification is done on the production line without extra setup. Completed décor files are stored on a server for future use, and then prior to printing, the files are queued to the printer, which can cycle through one, or tens of files at a time. The printer makes use of “variable data printing” technology, so elements such as text, graphics and images may be changed from one printed piece to the next without stopping or slowing the printing process. This printing capacity effectively breaks through the traditional limit of 10 different repeating plank designs common in conventional laminate flooring production.

The printing is done with a four-head inkjet printing machine that can run up to 100 meters a minute with a 300 dpi resolution. Each print head is dedicated to just one CMYK color and contains pumps, valves and filters that are governed by system controller software. As ink is pumped in a continuous stream through the nozzles of the print head it is broken into droplets via a piezoelectric actuator. Some of the droplets are charged, and as they pass over the high-voltage deflection plate the charged droplets are deflected to hit the surface. The uncharged droplets are caught in a gutter and returned to the ink supply. The system is very fast because there is no major restriction to speed aside from how fast the ink can be pumped through the print head nozzles.

Jen s Fandrey, Director of Project Mana gement , Kleiberit

Digital inkjet printing commonly uses a UV ink or solvent-based ink, which produces the signature inkjet odor. NextFloor’s process is able to use eco-friendly water based inks because of the custom print base coat that fixes the ink and gives the image proper light and water fastness. An added bonus is that the water based inks are cheap, costing about 1/10 the price of UV ink.

Protecting the Digital Print

A plank of HDF with a digitally printed image cannot perform as flooring until it receives surface treatment. NextFloor uses a twostep process of HotCoating PUR topped with acrylic UV lacquer to protect the flooring from wear and give the finished product the right appearance of gloss and depth of color. Jens Fandrey, Director of Project Management for Kleiberit headed the team that developed the PUR HotCoating used in the initial finishing treatment. “The philosophy behind digital printing is the same as HotCoating,” says Fandrey, “both emphasize individual, creative design and technical performance.”

The high speed of the direct digital printing (about 100m or 330 ft per minute), combined with the water-based inks, makes the conventional process of laminating a wear-resistant overlay impractical. Instead NextFloor uses a reactive PUR HC (Polyurethane Hot Coating) hot melt system to give the surface of their flooring the desired wear resistance. Because the performance is directly related to the thickness of the applied PUR HC layer, the coat weight can be adjusted to meet customer requirements (for example, about 40 grams/sqm are enough to give the surface AC3 class properties). The specialized PUR contains aluminum oxide particles and is solid at room temperature. When melted in the pre-melter the PUR HC is more viscous then traditional liquid lacquer, creating a very homogenous wear layer with extraordinarily shock resistant. A single roll coater applies PUR HC to the digitally-printed planks, which chemically cross-links with the humidity in the air and the substrate to cure without additional energy sources. The PUR HC treatment is so flexible that it can be profile wrapped or carry dimensional embossing.

An additional very thin layer of Kleiberit’s UV curing acrylic lacquer TopCoat allows for precise variations in gloss level and gives the NextFloor surface scratch resistance. It also lets the PUR HC to cure over a longer period without damage because the UV TopCoat gives immediate scuff protection.

The Future Now?

Bipan and its partners’ care in developing a viable means of direct digital inkjet printing for flooring is right in line with the demands of the consumer market. In addition to the benefits of producing high-fidelity custom designs at incredible speed, an unbeatable advantage of the digital décor flooring product is its low environmental impact. Compared to conventional laminate products, manufacturing NextFloor takes significantly less energy and creates less pollution. And considering the ecologically benevolent nature of waterbased inks and surface treatments that perform without emitting VOC’s, NextFloor will certainly get a lot of attention from professionals designing around LEED points. The innovation exhibited by the creators of NextFloor is just one example of how advancing technology can be applied to meet the increasingly high expectations of the consumer market. The applications of direct digital inkjet printing will keep designers and manufacturers busy for a while, but the question always remains, what’s next?