The use of ultraviolet light to achieve instant rapid drying effects has been a concept that has been developed for many years. Today, the flexographic and narrow web printing industry has always appreciated the many advantages of UV drying. After the application of UV-curable inks, coatings and adhesives, it is widely believed that the benefits include color consistency, environmental factors, physical properties, print quality, printing processes and screen printing effects.
UV (ultraviolet) and EB (electron beam) technologies can quickly cure or dry specially formulated inks, coatings, and adhesives, increasing production speeds, improving physical properties, and producing almost no air pollution compared to conventional methods.
"When photoinitiators absorb UV energy and initiate the polymerization of monomers to form solids, which are UV cures, we know most of them," said Jeff Peide, Sales Manager at Primarc UV Technologies in Fairmont, New Jersey. Ink or paint is a liquid, and when the moisture or solvent therein is evaporated, it becomes dry, and when the solvent volatilizes, the ink pigment is left to form an image, and the UV-curable material undergoes a chemical reaction, ie, solidifies, leaving a deeper density. image."
Curing and drying equipment The curing equipment involved in the above applications can be divided into several categories based on their effective space, curing speed and other considerations.
The UV curing system usually consists of a high voltage power supply, a control panel and a curing head. The curing head contains the necessary components for transmitting UV energy. The energy is transmitted to the ink or coating of the dielectric material. The medium is from the curing head. Pass above or below. According to Peide, the curing head usually includes a UV curing lamp (UV light source), a reflective system (to concentrate UV energy to the surface of the print media), and a cooling device (to maintain the proper operating temperature of the UV lamp).
Mr. Jimmy McCusco, president of the Americas Honle UV in Marlborough, Maryland, points out that there are three types of lamps commonly used for UV curing: mercury gas lamps, metal halide lamps, and xenon lamps. He said: "The mercury lamp is the mainstream of UV lamps and has three main output spectra, which are 254, 312 and 365 nm. The metal halide lamp has a wide spectral range between 350 nm and 450 nm. Mercury lamps are most commonly used, but when they are colored Heavy, thicker inks or light-blocking inks require halogenated metal lamps, which emit mainly spectral wavelengths slightly above 400 nm, and he adds that most of the xenon lamps are used for wood curing rather than the paper processing industry.
Medium-pressure mercury gas lamp (electrode type) has many different lengths for adapting to various machines and applications, the shape is 1′′ or 25mm diameter quartz tube. The lamp is filled with argon or helium, and a small amount of mercury; both ends of the lamp After the power is turned on, an electric arc is formed between the two electrodes to vaporize the mercury, and the resultant composite energy released from the lamp is mainly white light, infrared light, and ultraviolet light.
Of course there are electrodeless lamps. The lamp emits the same spectrum as the electrode type, but the mechanism is completely different. Electrodeless lamps rely on electromagnetic fields to emit microwaves instead of arcs. Lamps may be filled with different materials depending on the application requirements. Janet Geyer, Senior Product Manager at Fusion UV Systems, said: "While microwave energy lamps have remained stable from the start, the output intensity of arc lamps (referring to mercury lamps) will decay with use. Microwave lamp life can last from 300 to 6,000 hours ( Depending on the bulb, the output power is stable every day.†The lifetime of the metal halide lamp produced by Fusion UV is up to 6,000 hours, and most mercury lamps can only guarantee 1000 hours. Geyer also mentioned that mercury lamps are relatively expensive and not very common in the narrow web processing industry. He said: "There is one difference between arc lamps (or mercury lamps), that is, you can choose any length. The longest product of our company can reach 10". If your printer is wider than this size, you can use two lamps together. In this way, initial equipment investment may be more, but it is better from the quality of long-term product production. â€
Dan Norton, head of marketing at UV Research (Research) in Brea, Calif., believes that the lamp is only one of the key components of the UV curing system. "What really makes the UV system work is the design of the mirror. This part is responsible for focusing the energy on the solidification point. Without the mirror, the lamp must be 1/4 inch high close to the substrate, and it is likely to burn. That's why mirror mirrors are always kept clean,†he said.
Eleanor Midlik, president of Prime UV Systems in Carol Stream, Ill., also agrees that most UV systems must have well-focused reflective systems. She said: "The mirrors concentrate UV energy on a narrow lane of the web, which is why UV curing speed is increased."
Mr. Norton said there are three designs of reflectors. "There are paraboloids, ellipses (most commonly used), and focused ellipses (ie, elliptical mirrors in reflective designs for greater intensity). The smaller the diameter of the lamp, the smaller elliptical mirror built into the focusing mirror. More direct rays will be provided instead of reflected light. The intensity of UV light will be reduced each time it is reflected,†he said. "In parabolic mirrors, the UV rays are refracted in the mirror three or four times before reaching the focal point, and therefore the energy loss is greatest." Norton explained that parabolic reflectors are mainly used for speed requirements that are not very high, and that the cured area is large Happening.
Cold UV
A few years ago, the industry began to hear about "cold UV". David Horton, head of sales at Ohio State-based GEW, believes that cold UV is unreasonable. He said: "It's not really cold, but the 'cooling' reflector is coated with a dichroic coating (a special optical splitter coating). ), can absorb heat and reflect the UV wavelength." Mr. Norton further explained: "Cooling UV is the removal of IR (infrared) from the coil or substrate process. This is a NASA (NASA) approved This type of dichronic coating is used to accomplish this; the coating does absorb short-wavelength and infrared wavelengths in the light. In addition, we can also use double-glazed glass. The glass is located between the tube and the substrate; glass One of the layers is a hot mirror cords coating that reflects infrared rays or heat into the irradiator housing. The heat is then discharged by the exhaust fan so that it is not transmitted to the substrate." Cold UV is mainly used for the processing of heat-sensitive films and is usually expensive. According to Mr. Norton, each device is usually about 10% more expensive. (To be continued)
UV (ultraviolet) and EB (electron beam) technologies can quickly cure or dry specially formulated inks, coatings, and adhesives, increasing production speeds, improving physical properties, and producing almost no air pollution compared to conventional methods.
"When photoinitiators absorb UV energy and initiate the polymerization of monomers to form solids, which are UV cures, we know most of them," said Jeff Peide, Sales Manager at Primarc UV Technologies in Fairmont, New Jersey. Ink or paint is a liquid, and when the moisture or solvent therein is evaporated, it becomes dry, and when the solvent volatilizes, the ink pigment is left to form an image, and the UV-curable material undergoes a chemical reaction, ie, solidifies, leaving a deeper density. image."
Curing and drying equipment The curing equipment involved in the above applications can be divided into several categories based on their effective space, curing speed and other considerations.
The UV curing system usually consists of a high voltage power supply, a control panel and a curing head. The curing head contains the necessary components for transmitting UV energy. The energy is transmitted to the ink or coating of the dielectric material. The medium is from the curing head. Pass above or below. According to Peide, the curing head usually includes a UV curing lamp (UV light source), a reflective system (to concentrate UV energy to the surface of the print media), and a cooling device (to maintain the proper operating temperature of the UV lamp).
Mr. Jimmy McCusco, president of the Americas Honle UV in Marlborough, Maryland, points out that there are three types of lamps commonly used for UV curing: mercury gas lamps, metal halide lamps, and xenon lamps. He said: "The mercury lamp is the mainstream of UV lamps and has three main output spectra, which are 254, 312 and 365 nm. The metal halide lamp has a wide spectral range between 350 nm and 450 nm. Mercury lamps are most commonly used, but when they are colored Heavy, thicker inks or light-blocking inks require halogenated metal lamps, which emit mainly spectral wavelengths slightly above 400 nm, and he adds that most of the xenon lamps are used for wood curing rather than the paper processing industry.
Medium-pressure mercury gas lamp (electrode type) has many different lengths for adapting to various machines and applications, the shape is 1′′ or 25mm diameter quartz tube. The lamp is filled with argon or helium, and a small amount of mercury; both ends of the lamp After the power is turned on, an electric arc is formed between the two electrodes to vaporize the mercury, and the resultant composite energy released from the lamp is mainly white light, infrared light, and ultraviolet light.
Of course there are electrodeless lamps. The lamp emits the same spectrum as the electrode type, but the mechanism is completely different. Electrodeless lamps rely on electromagnetic fields to emit microwaves instead of arcs. Lamps may be filled with different materials depending on the application requirements. Janet Geyer, Senior Product Manager at Fusion UV Systems, said: "While microwave energy lamps have remained stable from the start, the output intensity of arc lamps (referring to mercury lamps) will decay with use. Microwave lamp life can last from 300 to 6,000 hours ( Depending on the bulb, the output power is stable every day.†The lifetime of the metal halide lamp produced by Fusion UV is up to 6,000 hours, and most mercury lamps can only guarantee 1000 hours. Geyer also mentioned that mercury lamps are relatively expensive and not very common in the narrow web processing industry. He said: "There is one difference between arc lamps (or mercury lamps), that is, you can choose any length. The longest product of our company can reach 10". If your printer is wider than this size, you can use two lamps together. In this way, initial equipment investment may be more, but it is better from the quality of long-term product production. â€
Dan Norton, head of marketing at UV Research (Research) in Brea, Calif., believes that the lamp is only one of the key components of the UV curing system. "What really makes the UV system work is the design of the mirror. This part is responsible for focusing the energy on the solidification point. Without the mirror, the lamp must be 1/4 inch high close to the substrate, and it is likely to burn. That's why mirror mirrors are always kept clean,†he said.
Eleanor Midlik, president of Prime UV Systems in Carol Stream, Ill., also agrees that most UV systems must have well-focused reflective systems. She said: "The mirrors concentrate UV energy on a narrow lane of the web, which is why UV curing speed is increased."
Mr. Norton said there are three designs of reflectors. "There are paraboloids, ellipses (most commonly used), and focused ellipses (ie, elliptical mirrors in reflective designs for greater intensity). The smaller the diameter of the lamp, the smaller elliptical mirror built into the focusing mirror. More direct rays will be provided instead of reflected light. The intensity of UV light will be reduced each time it is reflected,†he said. "In parabolic mirrors, the UV rays are refracted in the mirror three or four times before reaching the focal point, and therefore the energy loss is greatest." Norton explained that parabolic reflectors are mainly used for speed requirements that are not very high, and that the cured area is large Happening.
Cold UV
A few years ago, the industry began to hear about "cold UV". David Horton, head of sales at Ohio State-based GEW, believes that cold UV is unreasonable. He said: "It's not really cold, but the 'cooling' reflector is coated with a dichroic coating (a special optical splitter coating). ), can absorb heat and reflect the UV wavelength." Mr. Norton further explained: "Cooling UV is the removal of IR (infrared) from the coil or substrate process. This is a NASA (NASA) approved This type of dichronic coating is used to accomplish this; the coating does absorb short-wavelength and infrared wavelengths in the light. In addition, we can also use double-glazed glass. The glass is located between the tube and the substrate; glass One of the layers is a hot mirror cords coating that reflects infrared rays or heat into the irradiator housing. The heat is then discharged by the exhaust fan so that it is not transmitted to the substrate." Cold UV is mainly used for the processing of heat-sensitive films and is usually expensive. According to Mr. Norton, each device is usually about 10% more expensive. (To be continued)
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