HP Scitex FB6100 Printing Technologies - Page 17

high tensile strength and is lightweight, it is durable outdoors, and it is recyclable46. HDPE is also resistant to many solvents, and this feature gives HDPE widespread use in packaging for food and chemicals. But, it is this solvent-resistance that poses an issue for image quality and print durability: when printing HDPE materials with aqueous and low-solvent inks, the ink vehicle cannot soften or dissolve the surface. Therefore, no interface layer forms between the substrate and the colorant layer to give good adhesion and print durability. Tyvek® is formed from HDPE fibers fused together under heat and pressure. The surface of a Tyvek® sheet is a matrix of randomly-oriented fibers with large, open pores. Pigments can be carried deep into the fiber matrix when ink penetrates the surface of untreated Tyvek®. When this happens, a print may have high color bleed and feathering, low edge sharpness, low color saturation, reduced color gamut, and low optical density. To improve imaging performance and print durability of HP Latex Inks and HP low-solvent inks on HP DuPont™ Tyvek® Banner and HP HDPE Reinforced Banner materials, HP developed a proprietary surface treatment employing a blend of polymers designed to work with these inks. This treatment is applied during manufacture of the banner material and is called HP Surface Treatment Technology. The HP Latex Inks and HP low-solvent inks wet and dissolve these polymers to control ink spread and penetration. After the ink vehicle evaporates, the colorant layer forms a durable bond to the treated HDPE surface. HP Surface Treatment Technology on HDPE-based substrates improves image durability, color saturation and color gamut, and edge sharpness. Coated Media Coated media have an ink-receptive layer applied over an absorbent or nonabsorbent core. The imaging characteristics of coated print media are determined by the physical and chemical characteristics of the coating; the mechanical properties of the print (e.g., thickness, weight, and stiffness) are determined by the core. In general, the highest levels of image quality are obtained by using coated media recommended for the inks in the printer.47 Original HP inks and coatings on HP large-format printing materials are developed together, and both are manufactured with high standards of quality control to give consistent, high-quality results. The coating absorbs inks in a controlled manner to give predictable drop spread ("dot gain") and colorant penetration. This produces dots with consistent size, controls color-to-color bleed, and reduces print dry-time.48 Coatings can provide the uniform, bright, white background essential to accurate color reproduction, and a surface finish (e.g., glossy, semi-gloss, and matte) appropriate to the application. These features are especially important in photographic, fine art, technical and presentation graphics, and graphics arts applications. The physical and chemical interactions between ink and the coating are so important that the display permanence and water-resistance of prints, especially those made with dye-based aqueous inks, is given for specific inks on specific printing materials.49 Setting ink limits and linearizing the printer for the inks and printing material can give the widest color gamut, the greatest dynamic range for each ink color, and consistent color in print production. Generating an ICC Profile for the ink, print mode, and printing material is important for color accuracy.50 There are three main types of coatings: porous coatings, nanoporous coatings, and swellable coatings. 46 HP offers the HP Large-format Media take-back program in the U.S. and Europe, through which most HP recyclable signage media can be returned, availability varies. Some recyclable papers can be recycled through commonly available recycling programs. For details visit www.hp.com/go/recycle. Aside from this program, recycling opportunities for these products are currently only available in limited areas. Customers should consult local recycling resources for recycling these products. 47 See information on supplies recommended for a specific HP printer at www.hp.com/go/designjet/supplies 48 Primarily, this is the time required before the print can be handled without smearing the ink. It may take hours or days for the bulk of the ink vehicle to evaporate depending on conditions of temperature and humidity. 49 Display conditions also apply. See www.hp.com/go/supplies/printpermanence 50 HP Designjet Z-series printers have a built-in spectrophotometer that can automatically generate an ICC profile. HP's Closed-Loop Color Calibration delivers consistent results for a combination of inks and printing material. 17