Inkjet printing coating matters (2)

Media for Thermal Inkjet Printers - In general, paints for dye-based inks are "absorbers", which are simply capable of expanding and absorbing ink. These coatings are commonly used on photographic media to capture the ink and attach it to the surface of the substrate, resulting in high image quality.

Matte coated paper usually has a clay coating that acts like a filter membrane and quickly draws ink onto the surface of the media. These coatings produce good image quality and have moderate ink saturation. They are generally widely adaptable to thermal and piezoelectric printers.

Porous coatings are also widely used, but they are mainly used for pigment inks. This was a hot topic in the late 1990s, when the lightfastness of dye-based inks was considered to be a major obstacle for users who wanted to engage in inkjet printing of outdoor durable graphics products. In general, dye inks have a large range of hue, while pigment inks have better outdoor durability. The porous coating consists of a porous layer and hollow sachets. The ink penetrates the surface of the coating and fills the sachets where the ink is captured by the coating. Porous paint is divided into glossy and dull. The former is used for photo-type dielectric materials, and pigment-type inks are used to obtain photo-like output. Matte-type paints are used for outdoor vinyl materials and flags.

Again, the manufacturer chooses the coating based on how the media is used. As mentioned earlier, photo media is a typical example of indoor application media. When the medium is used indoors. For photo effect images, glossy porous or absorbent coatings are preferred. Outdoor coatings not only accept ink, but also withstand harsh outdoor environments. Matte, porous coatings are best suited for durable substrates because they accept and protect pigmented inks, which helps improve the outdoor durability of printed images.

Media for piezo printers - The coating principle applied to thermal ink jet printer media is equally applicable to media used in piezoelectric ink jet printers. The use of porous clay coatings on both types of presses is fairly consistent, but may be more suitable for piezoelectric printers. Non-porous absorbent coatings like those used for photo media may be used by more specialized printers with piezoelectric printers. These coatings work well with some piezoelectric dye inks but are unlikely to be used with other inks. Media manufacturers often publish their product compatibility charts and list the presses they use.

Manufacturers apply different techniques to apply coatings to media. These technologies fall into two broad categories: pre-metering techniques and post-metering techniques. The main difference between the two is how to achieve the required coating weight. The pre-metering technique is to apply only an exact amount of paint, similar to squeezing a tube of toothpaste at a controlled rate. After that, the metering technique involves applying a suitable amount of paint on the media. After metering, the excess is removed and the coating is recycled.

Pre-metering techniques include single-layer and multi-layer slot die extrusion coating, curtain coating, and multilayer grading coating. These coating methods are highly homogenous and each method is equipped with a pumping system that ensures that the coating fluid is delivered in one place and does not need to be repeated. Post-metering techniques include gravure, roll and reverse roll coating, these techniques are generally used to coat thinner adhesion-promoting coatings.

Regardless of the method used, accuracy and consistency are key to coating inkjet media. The thickness of the coating is one of many parameters that the manufacturer monitors and follows strict technical standards because the thickness of the coating affects the color, density, and color saturation of the final printed image. Between one roll or each roll, or between one job and the next, the inconsistent thickness of the coating will eventually give the user a different color product. This is why it is so important to carefully control the paint and assess the quality of the paint. It guarantees that the products you buy today will print the same effect as the products you bought last month.

For all types of coated inkjet media, it is recommended to adopt the same processing and imaging practices. The best printing performance will be obtained in a relative humidity of 40% to 60%. Therefore, the media must be stored in a controlled humidity environment. And printing. Avoid leaving fingerprints on the imaging surface. When not in use, store the media in a plastic bag and use a rope to hang the plastic bag to hold the vinyl media. Do not lay it on the table because the plasticizer in the vinyl media. Will migrate to the coating.

Over-saturation of ink is the root cause of many printing failures. All of the coatings mentioned in this article have a limited amount of ink uptake, depending on each coating, substrate, and press. There are some indications that the ink of the image is over-saturated, such as blotting, penetrating, wrinkling (on matt paper), and slow drying. Media manufacturers should recommend the saturation limits of their products, and it is best to understand them before starting printing. Saturation limits and recommended processing procedures are usually printed on the application guide for each product.

Also pay attention to the incompatibility of inks and media. A bad combination of the two usually shows signs. When printing photo-type media in incompatible conditions, long drying times are a major problem and can cause images to become sticky. To avoid this failure, you can purchase photo media with a printer-specific or universal coating. The photo media optimized for the Heolett Packard 5000 can be printed on this press but may not be as easy to use on the Encard. vice versa. Even universal paint has a "Meaning" press. On some printing presses it may have excellent performance, while on other printing presses it has a general effect. Once again, check with the media manufacturer to ensure that the purchased product is compatible with the press.

About half of the digital outputs are finally recombined. This raises some special considerations. For the composites to adhere, the surface of the media needs to be completely dry. This ensures that the print is completely dry before it is recombined. Some digital media may also have a backside coating to prevent warping and improve stability. These backside coatings may affect the adhesion of prints to decorative materials, such as foam sandwich panels. For best results, test composite laminate materials using media prior to receiving the job.

When selecting the type of composite layer to be used, the media, the type of coating, and the intended application, such as whether the matte paper is subjected to thermal recombination, need to be considered, and problems are rarely encountered with this method. Conversely, vinyl substrates should not be thermally compounded with polyester films. Under thermal compounding and changes in environmental conditions, after the images are fixed, the two materials expand and contract at different rates, with the result that the composite layers may separate. Ethylene materials can be composited with fluoropolymer films or pressure sensitive ethylene.

Glossy photo media is also difficult to heat film composite, so it is generally recommended to laminate a layer of pressure sensitive ethylene. Another alternative is to use a glossy photo-type media and then thermally laminate a thin film. The glossy photo media has a textured, rough surface that allows the composite layer to adhere firmly.

Shelf life is another factor that affects the performance of the media. In general, most ink-jet media have a shelf life of two years. The exception is transparent vinyl resin, which can have a shelf life of 6 months to 1 year. Because most transparent vinyl resins contain plasticizers to maintain their flexibility, plasticizers can migrate from time to time to the surface of the vinyl resin, thereby affecting the color of the ink printed on the vinyl resin.