Mimaki Introduces a New Generation of Latex Printers

About five years ago, latex inkjet printers were introduced to the sign market, rapidly gaining acceptance as affordable alternatives to solvent and ecosolvent systems. This novel technology certainly filled a big void in the market. Any of the curling issues that printers encountered when printing on some pressure sensitive vinyl films with solvent and ecosolvent inks were resolved because latex inks are water based.

Latex inks also dry instantly if cured at the recommended temperatures. That meant that you could laminate prints immediately after printing. Solvent inks, on the other hand, are not completely cured after printing. Before laminating printed vinyl graphics, shop owners had to wait for the prints to outgas. That takes time...a minimum of 24 hours under ideal conditions. Who has time today, especially when you have an anxious customer breathing down your neck?

As wonderful as the first generation of latex printers were, they were not without their issues. The high heat required to cure inks could cause tunneling of vinyl films on their release liners. High heat could also deform some films and discolor others.

If you heard about these heat related issues, and they dissuaded you from buying a latex printer, recent technology developments should give you a reason to take a second look. This second generation of inks is also more durable and glossier than precedent versions. The newer inks are also denser and more opaque, which provides greater hiding power when printing on colored stock.

While latex ink and printer technology improved in several areas, two key features set the Mimaki JV400LX latex printers apart from earlier generations of latex printers. The Mimaki printers are the first latex printers on the market with white ink. That development is huge, because it provides the operator with the capability of printing on color media, reflective sheeting and metalized films, such as our VinylEfx® print media. It also permits production of double-sided window graphics on clear films.

The other significant difference is that the Mimaki latex printers cure at much lower temperatures than the first generation systems. The first generation of latex printers typically required curing temperatures of 100

°C or 212°F. That's the boiling point of water. At these high temperatures, the water in the ink boiled and turned to water vapor. Heating also coalesces the individual latex resin particles into one mass and binds these particles to the substrate.

All of this sounds great, but the reality was that what you saw was not always what you got. Here's what I mean. Temperatures of the earlier units could fluctuate greatly. You could set the temperatures in the profile at 212°F, but the actual temperatures at the printer could reach as high as 220°F or higher. That's hot enough to fry an egg! After the printer stopped printing, the media could remain under the heater and continue to cook. At high temperatures, some media could discolor. Other media, such as polyester film, could permanently deform.

There are a few games that you can play to successfully print heat sensitive material. You could lower the curing temperature, for example, to 88°C or 190°F. The tradeoff is that the ink may not be entirely curing and you have to wait for the ink to dry. Another solution is to lower the ink density. The problem is that some colors may look a little washed out. Another fix is to increase the number of passes. While you get a nicer looking print, production time is increased.

With the new Mimaki JV400LX latex printer, you don't have to play these games. Heating consists of three stages: preheating of the media, heating during the print mode, and post heating. Most media, cures at 60°C or 140°F. Some media, such as polyester, does require curing temperatures as high as 70°C or 158°F. At any rate, the temperatures are significantly lower, and when you are done printing with the Mimaki system the prints are completely dry and ready for lamination.

Because the Mimaki latex printers cure at much lower temperatures than the first generation of latex system, it's energy consumption and operation costs are significantly lower.

The Advantage of White Ink: The Mimaki JV400LX printers are the first latex printers with white ink. One of the problems with white inks is that the pigment, which is suspended in water and is heavier than other pigments, tends to settle at the bottom of the ink reservoir. Mimaki's solution was to incorporate a recirculating feature into their system.

The addition of white ink opens up a number of design possibilities when printing on colored vinyls, clear window films, reflective sheeting or metallic films. After printing a base layer of opaque white, you can print colored images on top of it. The white blocks out where the image is, leaving the colored or metalized media as the background.

When printing on clear films, a white layer allows you to print double-sided window graphics. In imaging on both sides of clear film, the printing sequence is to print a wrong reading image, then print block out white and finish by printing a right reading image.

For printing on colored substrates, Mimaki recommends the Color Logic software, which allows spot printing of white inks to mask the substrates prior to printing process colors.

According to Richard Ainge, the Chief Technology Officer for Color-Logic, Mimaki's introduction of the world's first latex printer with white ink capabilities gives user the ability the achieve dramatic metallic special effects when printing on metallic or reflective substrates. "The Mimaki white ink enables graphic designers to block the effect of metallic substrates where the metallic effort is not desired," Ainge says. "Using the Color-Logic software to create the necessary white ink masks significantly reduces design time. Using our software with the Mimaki latex printer also enables designers to accurately assess their metallic designs without expensive on-press test prints."

Latex Advantages: Latex inks feature many advantages of solvent inks. Because latex inks are water based, you have none of the hazards associated with solvent inks. There is no obnoxious solvent odor. No dangerous OVCs to pollute the environment, so there's no need for a special ventilation system. No hazardous waste is produced. That's good for the environment and it's good for the health of the personnel operating the equipment.

If you are allergic to latex rubber, there is no need for you to worry about skin irritations caused by the HP latex inks. The latex in the HP inks is not the same as natural rubber. These synthetic inks are non-allergenic.

Latex inks are not only more ecofriendly, but they also provide outstanding outdoor durability, adhering to a wide variety of non-topcoated print media used in the sign market. This media includes banner material, polycarbonate film, polyurethane heat transfer films and pressure-sensitive vinyl.

Latex inks are embed into the surface of the substrate. Good adhesion and robust pigments allow the inks to withstand the elements. These inks were specifically formulated to meet or exceed the demanding requirements of the billboard and sign industries. They are ideal for exterior applications such as outdoor advertising, banners, transit advertising, vinyl lettering and graphics on signs and vehicles.

The second generation of latex inks produces denser, more durable colors. The dried ink is also very flexible which makes it suitable for vehicle wrap graphics which are stretched during vinyl application.

Used for outdoor signage and vehicle applications, graphics printed with Mimaki inks provide up to three years exterior life without a laminate. Although lamination is not required, it's not a bad idea. Lamination provides protection from abrasion and chemicals, as well as additional fade resistance from exposure to UV light. With lamination, durability is expected to be up to five years. The reason that latex inks are so durable compared to other types of inks is that the colorant is a pigment, not a dye.

Outstanding durability is not at the sacrifice of the production speed or print quality. The latex inks are suitable to print high resolution prints with vibrant colors of indoor applications such as point-of-purchase (POP) displays, wall graphics, trade show graphics and museum graphics.

The new Mimaki JV400LX printer features six color print process (CMYK, orange and green) plus white. The orange and green inks, which were not available with the first generation of latex printers, expand the color gamut. That makes matching specific PMS colors or company logo colors a lot easier. In fact, the color gamut for the second generation of latex inks allows the printer to reproduce 93% of the color in the Pantone color chart.

Another difference between the newer latex printers and the first generation of latex printers is that Mimaki incorporated piezo rather than thermal inkjet print heads. The piezo print heads are permanent fixtures rather than consumable. That's a big deal because piezo heads allow for variable dot printing in three different droplet sizes. The result is smoother tonal transition and a grain-free, higher quality image.

Mikaki's David Robinson says that "the quality and resolution of the JV400LX is so good that you can actually print copy as small as 2 point text. You can't do that with the first generation of latex printers."

The piezo print heads in the Mimaki printers also operate at lower temperatures then thermal heads. That lower operating temperature makes them more durable and more reliable.

In manufacturing, time is money. Printing at the six-pass mode, the output of the JV400LX is about 20 square feet per hour. At the higher resolution 12-pass mode, output is a respectable 8 square feet per hour. Robinson says that the newer generation of latex printers is 20% faster than the first units that came out.

Conclusion: Improvements in the latex printers certainly warrants your consideration if you are shopping for a new wide format digital printer. With their cold cure inks and white ink capabilities, Mimaki expanded the range of substrates that latex printers can print on. Also, the new Mimaki printer offers print providers a system that yields a high output without sacrificing print quality

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