Temperature control during screen printing

This article mainly describes the impact of flash devices on productivity, and what problems printers will encounter when they do not control the temperature.

For those of us who have long been working in the field of garment screen printing, we all know that the fast curing in the printing process is a very important and very professional step. But now, flash devices have become like screens and have become a very common tool in the production process. However, if people do not understand the entire printing process thoroughly, then there will be problems in many aspects, and even affect the normal production of the printing plant. In this article, we will discuss a series of issues related to flash curing in the garment printing process and find the best way to work together with the flash-curing device and drying system.

Flash unit

I mentioned in previous articles that many printers want to illuminate images at temperatures that are not productive. It is true that we often need to use very high temperatures in such an era of speed, especially on fully automatic presses. The solution to the problem is to find the best speed that will allow the ink film to dry quickly without affecting the substrate.

The best flash device on the market that can control the temperature of the ink film during rapid curing is the quartz flash system, which can reach a specific temperature in a short time and can be quickly cooled. These devices allow people to better control the temperature, of course, you can also use IR flash device with a black panel to complete this work. Their special temperature control function allows you to significantly improve the control capabilities.

Another system that you can choose from is a black panel device that does not have a temperature setting feature that allows people to adjust the state of the switch through the switch. The only way to control or adjust such devices is to raise or lower the height between the device and the platen or garment surface. The only thing you can decide is which system to use for your service, but I think from a long-term perspective, you should still have the ability to adjust temperature and production returns.

Imprinting plate temperature

When the imprinting plate is exposed under the flash-curing device for too long and reaches an excessively high temperature, any problem may occur. For example, the adhesion between two ink films is not strong, the sublimation of polyester dyes on cotton/polyester blends with 100% chemical fiber materials, the substrate blistering phenomenon when printing anti-bleed inks, and the fiber and web Screen bonding and so on. This problem is likely to occur if people print garments of pure cotton texture in a relatively humid environment. Heating the moisture-containing fabric can increase the affinity of the emulsion coating on the screen so that the surface of the fabric is tightly integrated with the screen surface. When you want to remove the garment from the plate, you must stop production and remove the screen. This has caused a great waste of production time.

Although most printers claim to spray screens with silicon, the real purpose of doing so is to minimize the flash device temperature while achieving 125-250°F required for ink drying. Imprinting plates can absorb flash-curing device heat during production and become hotter as production progresses. You can find an ideal setting (time, membrane, and distance) based on the type of flash device you use to ensure that production can continue without adjusting the device. Those who cannot do this can only adjust the settings of the device to maintain the operating temperature during the production process.

Synchronous drying/flash

One problem that often arises in the flash and drying process is that people do not consider the effect of the ink film temperature when switching from the flash mode to the non-flash production mode. In general, you can use a dryer to increase the temperature of the screen-printed ink film from room temperature to 320°F for better drying.

When you print a garment that requires flash ink, you can send your shirt (ink film temperature up to 125°F) to the desiccator. In this case, the temperature of the garment surface can be combined with the ambient temperature in the dryer and the temperature of the ink film below the 320°F cure point can easily be increased to above 360°F. Once the temperature of the ink film containing the plastisol reaches 360°F, it can be melted again.

When printing anti-bleeding substrates, there is a problem that is inevitable. The anti-bleeding component in the ink film will begin to debond, leaving small pits on the overprinted ink film. This phenomenon usually occurs when the feed device is short-drying because the flash ink film does not have enough time to cool before passing through the drying oven. Many large printing plants have equipped their own dryer with a long feed device in order to reduce the temperature of the flash ink film. For those garment printers lacking longer feeding devices, the most important thing is to ensure that the garments are dried at the lowest possible temperature to reduce the possibility of these problems.

Exposing garments or ink films to excessive temperatures also tends to sublimate polyester dyes in blended fabrics. This effect does not manifest immediately at the end of the dryer, but over time, the polyester dye sublimates into the ink film, causing the garment to fade. During the period from one day to six weeks, the sublimation and fading phenomenon will occur anywhere in the garment, but the specific situation should be analyzed based on the content of the polyester dye in the fabric and the degree of sublimation of the dye in the curing process.

The role of flash device

The task of the flash device is to cause the underlying ink film to solidify. In general, people will flash the ink before printing the last color, that is, adding special effects. Although the flash device is often used as a flash-curing device, curing the ink film is only one of its most basic functions. Complete curing will hinder the adhesion between the ink layers. The only thing you need to do is make an ink film ready to accept the next layer of ink.

Once you have determined the temperature of your flash unit, you must maintain this temperature during production. If necessary, you can preheat the platen before production and then determine the minimum temperature required for solidification of the substrate. If people do not control the flash temperature in order to increase production speed, then the problems you face will always be more than you have! Therefore, in order to increase production efficiency, the first thing that needs to be done is to control the temperature during the printing process.