For screen printers that have introduced large-format inkjet equipment, laminating machines have become a must-have post-processing equipment for them. The original purpose of the film is to set up a barrier between the printed images to prevent them from being worn during repeated use. The laminating machine used in the printing industry mainly covers the surface of the printed matter with a thin film to prevent the image from being damaged by scratches and chemicals. However, the laminator has another application, which is to apply a layer of protective liquid paint to the printed matter. Liquid film technology is the focus of this article. We will focus on introducing the equipment, coating type, application range and benefits it has to do with this post-press processing.
Liquid laminating machine
The liquid laminating machine is actually a coating device. From the most basic point of view, prints must first be input into the laminator, then coated, and finally input. The intermediate and final steps of film coating mainly depend on the type of paint you choose. It can be either UV curable paint or water-based or solvent-based paint. For example, substrates coated with UV must be processed by a drying unit before output, and substrates coated with water-based paint can choose to add an infrared drying program according to the automation level of the laminator. Enhance the drying effect of printed matter.
In order to meet different needs of users, the liquid laminating machine also has a variety of different configurations and sizes. In today's printing market, people can choose either manual or automatic laminating machines or laminating machines that use sheet or roll paper.
UV laminating machines are generally divided into reverse roll type or three roll type systems. The water-based laminating machine generally applies the coating on the substrate, and then uses a wire rod (that is, a cylindrical metering rod) to reduce the thickness of the coating to an appropriate level. A squeegee or similar device can be used to scrape the paint off the back of the substrate.
IkeHarris, president of Daige, said: "This can't be regarded as roll coating, but wipe the coating on the substrate. When people need to apply precise coating, they need to use the special measurement commonly used in the laboratory In addition, this metering rod is also suitable for manual and large-scale roll-to-roll coater (aqueous coating process), it can make the coating machine produce smooth and uniform on the substrate Coating. "
The roll coater can use multiple ink rollers to transfer the printed image and complete the task of coating them. From the beginning of entering the roll coater, the substrate is either dried by ultraviolet or infrared rays, or dried naturally, but the latter takes a long time. Substrate conveying device integrated with some coating machines-usually a conveyor belt to send the coated substrate to the drying or curing system in time. As an alternative, one can also place the water-coated image horizontally so that it dries faster. This method is usually used on manual coating machines. Harris pointed out that water-based coatings require about 20 to 25 minutes of drying time.
Many recently launched UV liquid laminators can cure coatings at high speeds, and their speed can sometimes be as high as 100 feet / minute. In addition, they can also be designed to be very compact to save space. For example, the total length of this equipment can be controlled within 5 feet, which also includes the length of the conveyor, because only in this way, the laminator can quickly process the material.
The characteristics and number of jobs determine the type of liquid laminator you need. If you want to print banner patterns on mesh plastics or POP images on textiles, then it is best to choose an aqueous coating system, because the depressions on the printed surface of the material must be filled with liquid paint.
According to Jim Tatum, President of AdvancedFinishing Solutions (Pioneer Post-Processing Solutions), it is not the best choice to process this textile material with a UV liquid laminating machine, because the laminating equipment will apply the printing material at a very high speed. A thin layer of paint. Under the given operating parameters, this coating has little chance to fill the depressions on the substrate surface.
Tatum pointed out: "In this way, only part of the image you get has been coated and cured. When bad weather conditions and other destructive factors occur, this coating cannot protect the image at all." On the other hand, the aqueous liquid laminating machine can evenly coat the surface of the substrate, so that the depressions of the image can be properly protected. [next]
Protective coatings and their applications
With the increasing awareness of environmental protection in printing plants, UV coating has also been rapidly recognized in recent years. Most of the UV coatings used for printing images now do not contain VOCs (volatile organic compounds), so they can be easily converted into solids without evaporating any gas. Water-based paint is generally composed of 70% water and 30% resin, so it needs to be placed for a long time after the coating is completed, so that the moisture is evaporated before the substrate is rolled up or stacked. Tatum believes that people should consider evaporation when calculating the cost of waterborne coatings.
Tatum explained: “To get the same coverage as UV coating, you have to apply more coating to the substrate; therefore your cost must also increase. The benefit of UV coating is that it allows you to use a reverse Roll coating system or a three-roll coating system, and the coating it forms is very thin, generally between 6 and 20 microns. "
The advantages of water-based coating mainly come from the latest advancement of its formulation technology. Just a few years ago, the VOC content in waterborne coatings was as high as 2-3 lbs / gallon. Today, the VOC content of many coatings has dropped significantly. According to Tatum, the high VOC content is one of the main reasons for the yellowing of printed images. Therefore, he suggested that people use non-stearate resins in water-based paints to reduce the solvent content.
Although water-based and UV-curable coatings have made considerable progress, solvent-based coatings still have a place in the liquid film market. David Conrad, equipment product manager of Neschen America, said that in the field of sign production, solvent-based coating still dominates. Flexible display panels are best suited for solvent-based coatings, as this coating prevents the image from becoming brittle or cracking over time. The products printed on rigid substrates are more suitable for UV coating, because UV coatings do not have the ductile properties exhibited by other coatings, and because of this, this coating is not suitable for protecting the body image.
Tatum explained: "To protect the images of cars and boats, the paint you use must have at least 150% elongation. Because it needs to take care of rivets, intricate curves and other irregular printed surfaces. Here In this case, once the coating is cracked, the printed image will collapse. "
Generally speaking, one should choose water-based or solvent-based coating for the substrate according to the coverage or flexibility requirements. In addition, it should be kept in mind that understanding the high solid content in UV coatings is not conducive to their use on textiles and other special substrates. Speaking of which, we must remind those who intend to use inkjet printers to produce fine artworks and photographs: you should pay special attention to the use of liquid laminators to protect the printed images.
JimManelski, President of BullDogProducts, said: "If you are printing on water-based printers like Epson, Roland, HP and Canon-using water-based inks-then you need to apply liquid coating to the print to prevent it from getting water. Failure (due to the chemical composition or other substances on the wet or dry ink film, the printing ink or ink component has penetrated into areas that should not be reached during operation) or is exposed to ultraviolet rays. There are currently two types Canvas can be used on water-based printers, you can choose different coating methods according to the type of canvas. "
Water-repellent canvas requires water-based coating. This canvas can absorb a lot of ink, so there is almost no water failure. Manelski pointed out that the image printed on the waterproof canvas is difficult to maintain for a long time without going through the liquid film.
Another kind of canvas is called swelling canvas, which needs to be coated with a solvent-based material on the surface of the substrate, because the ink penetrating the surface of the substrate is likely to cause water problems under the influence of the surrounding moisture. Although the swellable canvas is more prone to this kind of failure than the water-resistant canvas, Manelski claims that he prefers the former, because in most cases, it can produce a wider color gamut.
Manelski believes that liquid laminators are a key factor in protecting beautiful prints because they can significantly reduce the possibility of prints being contaminated with dust and other substances. For example, liquid paint is easily entrained with small particles in the air when it is sprayed onto the surface of the print, causing permanent contamination of the image. He said: "Liquid film laminating machine can effectively solve this problem, because you are exposed to dry products during the operation."
Other products suitable for liquid compliance are: doors, furniture, walls, decorations and food packaging. For the above products and those printed images with traditional uses, you must be extra careful when choosing the coating formulation. Below we will focus on discussing effective methods for selecting paints for printed matter. [next]
Choose the right liquid
As we all know, UV can cure UV inks and coatings, but it also prevents UV liquid coatings from protecting printed images. Any kind of UV inhibitor will affect the curing of the coating. Therefore, the initial use of the UV liquid film is to prevent the printed image from being scratched and scratched. Tatum pointed out that the use of UV-cured coatings on images produced by UV inkjet printers is very good. He said that in most cases, water-based coatings are not suitable for UV inkjet prints, because cured UV ink can form a non-stick surface.
Harris recommends that customers who use solvent-based or environmentally friendly solvent-based inks use aqueous liquid lamination. He said: "If you apply water-based coating on outdoor prints, you will find that it can easily absorb the coating, because these substrates have been pre-coated before this time."
Another issue that needs attention is that water-based liquid coatings, like water-based screen printing inks, also contain certain solvents.
We also mentioned earlier: The VOC content of these coatings will decrease over time, but even so, you should keep a chemical safety data sheet for each water-based coating you use.
Solvent-based liquid coatings are mostly used on water-based prints. Their formulations can contain UV absorbers and stabilizers to prevent polymer aging caused by photooxidation and high temperatures. Solvent coatings can also contain some leveling agents, which can play a role in improving the smoothness of the coating surface.
Cost factor
The cost of replacing the plastic film with a liquid coating is a concern. According to Conrad, the cost of protecting images with liquid film is about US $ 0.02-0.03 / m2 (short-term display images) or US $ 0.30-0.38 / m2 (long-term use images printed on demand).
As Harris said: "The cost of plastic film is about 0.35-0.60 US dollars. So you can save a lot of costs by using liquid film."
The price of consumables is a factor that must be considered. In addition, the cost of waste generation and disposal is also a problem that cannot be ignored.
Tatum explained: "Every print that requires plastic lamination must be processed by a laminator, and it is difficult to find a plastic film that matches the size of the print. So you will definitely have a lot of leftover material And it also takes a certain amount of labor to process them. The liquid laminating machine not only has a very fast operating speed, but will not bring you any waste and garbage. "
Is it the best time to use liquid film?
Generally speaking, laminating is still more popular in the field of inkjet printing. But now that many screen printers have introduced digital imaging technology, it is now time for you to use new solutions to protect large format inkjet prints. The price of the liquid laminating machine depends largely on the type of equipment you choose. The price of UV systems is generally higher than that of water-based coating systems, because they use UV curing lamps, and the processing speed of printed materials is also faster. In many cases, UV coating machine paper is only a little cheaper than water-based coating systems with a processing width five times that of itself.
Tatum said: "The price of the primary water-based coating system is not expensive. If you can accept its price, you can easily transition to the UV system-you can experience in speed, cost and stackability The benefits of this system. The only disadvantage of UV coating is that it is not as flexible and flexible as water-based coating. "
Disposable Face Mask,Disposable Protective Face Mask,Cost Price Disposable Face Mask,Face Mask
JINAN XINSHUNYUAN PACKING CO., LTD , https://www.xsy-packaging.com