2. UV inks are printed with UV inks with bright colors and high image resolution. UV flexo printing is a very promising process from the perspective of environmental protection and technological development. UV ink is a photocurable ink that can change from liquid to solid at a certain wavelength of ultraviolet light irradiation. The advantages of UV inks are that they do not use solvents, which are beneficial to environmental protection, fast drying speed, low energy consumption, good gloss, colorful colors, water resistance, abrasion resistance, oil resistance, and solvent resistance.
The main components of UV-curing inks include photopolymerization prepolymers, photosensitive monomers, photopolymerization initiators, organic pigments, and additives. Photoinitiators in inks are compounds that are susceptible to light excitation and become excited after absorption of light. Free radicals, energy is transferred to photosensitive molecules or photocrosslinkers, causing UV inks to undergo photocuring reactions.
UV inks will only dry when exposed to UV light. Even if stored in the ink fountain for a long time, the performance will remain stable, the drying speed will be fast (up to 500 m/min) and thorough, solvent-free discharge, and there is no need to prevent contamination between the prints. By adopting powder spraying measures, the printing press and the workshop environment are clean and free from dust pollution. The printed paper can be recycled and recycled. When UV ink is used, the ozone generated by ultraviolet rays should be removed, and the protection against UV rays to the human eye should be taken care of.
3, water-based UV ink Water-based UV ink is a new research direction in the field of UV ink. The viscosity of prepolymers in general UV inks is generally very large and needs to be diluted with reactive diluents. However, currently used reactive diluents (acrylic esters) have different degrees of skin irritation and toxicity. For this reason, while developing low-viscosity prepolymers and low-toxic reactive diluents, the UV ink.
The use of ethanol as a solvent will make alcohol-soluble inks have good compatibility and excellent adhesion properties. Ethyl acetate, which erodes certain printing inks, can cause blooming of the ink. This problem often occurs in offset printing inks.
In the process of developing environment-friendly inks, the improvement of solvent-based inks should be enhanced at the same time to improve safety. The safety of the solvent is mainly reflected by the toxicity and flammability of the solvent. Special attention must be paid to:
(1) Ether is capable of generating explosive peroxides; (2) Non-flammable solvents or carbon tetrachloride can react explosively with metals such as sodium, potassium, calcium, magnesium, barium, etc.; (3) Trichloroethylene and Sodium hydroxide and potassium hydroxide are contacted to produce dichloroacetylene. Dichloroacetylene will explode due to oxidation.
Developed the same family has proposed not to use this type of solvent, I also in the national standard GB9685-94 food containers, packaging materials used in the use of additives for the health standards," paints, adhesives, inks used solvents are ethanol, butanol, Acetone and ethyl acetate. GB/T10004-1998 "Retort-resistant composite film, bag" provides a total solvent residue of 10mg/m2, and provisions of which benzene solvent 3.0mg/m2.
Waterless Offset Printing Inks – The most difficult part of realizing a balanced offset ink is to achieve the right ink balance. Too much water can wrinkle the paper and thin the ink film transferred to the paper. Too little water can make the ink uncontrollable and transfer to the non-graphic area. The ink-to-ink ratio also affects the viscosity of the ink, and in multi-color printing, there is a problem of how to control the post-printing ink to superimpose the previously printed ink. It is not easy to achieve the correct ink-water balance. The balance of ink and ink is influenced by various factors such as temperature, humidity, paper type, and printing speed. Waterless offset printing brings many benefits because there is no ink-ink balance.
One of the major problems with waterless offset printing is temperature control. The viscosity of the ink varies with temperature. During the printing process, the ink will heat up due to the friction between the ink rollers. When the temperature rises to a certain degree, the ink viscosity will become low and the printing plate will be dirty. If there is no self-cooling effect, perhaps the same problem will occur on a conventional offset press. The self-cooling effect causes the ink roller to pick up very fine water droplets from the plate, the water droplets float on the ink film, and return to the ink roller. When the water evaporates, the ink is cooled. To stabilize the ink viscosity, one solution is to use a special ink, which can maintain a constant viscosity over a wide temperature range; another small trick is to use a thicker ink during the long live printing process. The real solution, however, is to pump coolant through internal tubes on some of the rollers to stabilize the ink temperature. This method will add considerable cost to the new press, which is a purely expensive modification to the old press. In any case, this method can use the same ink and the same operating technology for the short live and long live.
Since no water weakens the ink film, waterless offset printing can have a higher ink density on the printed page, so the printed image has a larger color gamut; a four-color waterless offset proof looks like a traditional offset printing. Six color prints printed on the machine. Other benefits of the waterless offset press include shorter print setup time and less paper waste (this is especially important for short-form digital printing on the fly), there is no problem with the removal of excess dampener additives, and printing There is only a small amount of volatile organic compounds in the air of the workshop. In order to be able to use waterless offset printing, it is now more and more common to equip cooling rollers even on conventional presses. The fact that waterless offset printing is used is still acceptable to users even if operating costs increase.
When most successful waterless offset systems use special plates, 3 companies are developing special inks. In fact, only one type is a true waterless offset ink, but all three ink products have the advantage of eliminating the need to adjust the ink balance when printing.
(1) Single-Fluid inks Gauss has demonstrated Single-Fluid inks in Print 97, and the technical details have remained confidential. The concept is that traditional oil-based inks are emulsified with water. The emulsification process is achieved by a device that is mounted on a printing press and resembles a stirrer. The emulsified emulsion (pigmented mayormaise) is then added to the inking roller of the printing press. When it reaches the printing plate, the emulsion separates into components of water and oil. Gauss did not demonstrate its single-fluid ink technology at Drupa 2000, but it is said that the technology is still under development and was tested in a newspaper in the fall of 2000. Gauss has already registered "SingeFluid" as a registered trademark.
(2) Water-based ink Heidelberg Co., Ltd. cooperated with Sun Chemical to develop a water-based ink. Technically speaking, this product does not belong to waterless ink but is an oilless ink. However, like waterless inks, this ink avoids ink balance problems and it also has environmental benefits.
Heidelberg's inks require a silicon-containing plate to allow the non-imaged areas to repel ink. In addition, it also requires the printer to have a temperature control roll, but instead of a chill roll, this ink needs to heat the roll to 35°C and evaporate the excess water from the ink by heat, when the ink is attached to the plate, the final The total water content is 1%-2%. Although this temperature value is not very strict, it can be varied within the range of 10°C but it must be controlled. If the water evaporates too much, the ink will dry on the ink roller; if the water evaporates too little, the printing plate will tend to be dirty when printed. It is said that the ink will be heated to dry at 40°C, and if dried, it will have water resistance. When the ink is hot enough to dry immediately, no need for dusting (the press is usually done with talcum powder on the newly printed sheet to prevent the ink on the surface of the sheet below the sheet from contaminating the back of the sheet). . After 5 minutes, the degree of drying of the ink allowed the printer to carry the sheet by hand; after 15 minutes, the ink was dry enough to allow the printer to fold the sheet. In addition to the environmental benefits, water-based inks perform as well as the printer expects, have the same viscosity and viscosity as conventional inks, and produce the same maximum solid ink density on the page. At first, its price may be twice that of waterless offset inks now, but in the future its price will depend on the amount of ink produced. (To be continued)
The main components of UV-curing inks include photopolymerization prepolymers, photosensitive monomers, photopolymerization initiators, organic pigments, and additives. Photoinitiators in inks are compounds that are susceptible to light excitation and become excited after absorption of light. Free radicals, energy is transferred to photosensitive molecules or photocrosslinkers, causing UV inks to undergo photocuring reactions.
UV inks will only dry when exposed to UV light. Even if stored in the ink fountain for a long time, the performance will remain stable, the drying speed will be fast (up to 500 m/min) and thorough, solvent-free discharge, and there is no need to prevent contamination between the prints. By adopting powder spraying measures, the printing press and the workshop environment are clean and free from dust pollution. The printed paper can be recycled and recycled. When UV ink is used, the ozone generated by ultraviolet rays should be removed, and the protection against UV rays to the human eye should be taken care of.
3, water-based UV ink Water-based UV ink is a new research direction in the field of UV ink. The viscosity of prepolymers in general UV inks is generally very large and needs to be diluted with reactive diluents. However, currently used reactive diluents (acrylic esters) have different degrees of skin irritation and toxicity. For this reason, while developing low-viscosity prepolymers and low-toxic reactive diluents, the UV ink.
The use of ethanol as a solvent will make alcohol-soluble inks have good compatibility and excellent adhesion properties. Ethyl acetate, which erodes certain printing inks, can cause blooming of the ink. This problem often occurs in offset printing inks.
In the process of developing environment-friendly inks, the improvement of solvent-based inks should be enhanced at the same time to improve safety. The safety of the solvent is mainly reflected by the toxicity and flammability of the solvent. Special attention must be paid to:
(1) Ether is capable of generating explosive peroxides; (2) Non-flammable solvents or carbon tetrachloride can react explosively with metals such as sodium, potassium, calcium, magnesium, barium, etc.; (3) Trichloroethylene and Sodium hydroxide and potassium hydroxide are contacted to produce dichloroacetylene. Dichloroacetylene will explode due to oxidation.
Developed the same family has proposed not to use this type of solvent, I also in the national standard GB9685-94 food containers, packaging materials used in the use of additives for the health standards," paints, adhesives, inks used solvents are ethanol, butanol, Acetone and ethyl acetate. GB/T10004-1998 "Retort-resistant composite film, bag" provides a total solvent residue of 10mg/m2, and provisions of which benzene solvent 3.0mg/m2.
Waterless Offset Printing Inks – The most difficult part of realizing a balanced offset ink is to achieve the right ink balance. Too much water can wrinkle the paper and thin the ink film transferred to the paper. Too little water can make the ink uncontrollable and transfer to the non-graphic area. The ink-to-ink ratio also affects the viscosity of the ink, and in multi-color printing, there is a problem of how to control the post-printing ink to superimpose the previously printed ink. It is not easy to achieve the correct ink-water balance. The balance of ink and ink is influenced by various factors such as temperature, humidity, paper type, and printing speed. Waterless offset printing brings many benefits because there is no ink-ink balance.
One of the major problems with waterless offset printing is temperature control. The viscosity of the ink varies with temperature. During the printing process, the ink will heat up due to the friction between the ink rollers. When the temperature rises to a certain degree, the ink viscosity will become low and the printing plate will be dirty. If there is no self-cooling effect, perhaps the same problem will occur on a conventional offset press. The self-cooling effect causes the ink roller to pick up very fine water droplets from the plate, the water droplets float on the ink film, and return to the ink roller. When the water evaporates, the ink is cooled. To stabilize the ink viscosity, one solution is to use a special ink, which can maintain a constant viscosity over a wide temperature range; another small trick is to use a thicker ink during the long live printing process. The real solution, however, is to pump coolant through internal tubes on some of the rollers to stabilize the ink temperature. This method will add considerable cost to the new press, which is a purely expensive modification to the old press. In any case, this method can use the same ink and the same operating technology for the short live and long live.
Since no water weakens the ink film, waterless offset printing can have a higher ink density on the printed page, so the printed image has a larger color gamut; a four-color waterless offset proof looks like a traditional offset printing. Six color prints printed on the machine. Other benefits of the waterless offset press include shorter print setup time and less paper waste (this is especially important for short-form digital printing on the fly), there is no problem with the removal of excess dampener additives, and printing There is only a small amount of volatile organic compounds in the air of the workshop. In order to be able to use waterless offset printing, it is now more and more common to equip cooling rollers even on conventional presses. The fact that waterless offset printing is used is still acceptable to users even if operating costs increase.
When most successful waterless offset systems use special plates, 3 companies are developing special inks. In fact, only one type is a true waterless offset ink, but all three ink products have the advantage of eliminating the need to adjust the ink balance when printing.
(1) Single-Fluid inks Gauss has demonstrated Single-Fluid inks in Print 97, and the technical details have remained confidential. The concept is that traditional oil-based inks are emulsified with water. The emulsification process is achieved by a device that is mounted on a printing press and resembles a stirrer. The emulsified emulsion (pigmented mayormaise) is then added to the inking roller of the printing press. When it reaches the printing plate, the emulsion separates into components of water and oil. Gauss did not demonstrate its single-fluid ink technology at Drupa 2000, but it is said that the technology is still under development and was tested in a newspaper in the fall of 2000. Gauss has already registered "SingeFluid" as a registered trademark.
(2) Water-based ink Heidelberg Co., Ltd. cooperated with Sun Chemical to develop a water-based ink. Technically speaking, this product does not belong to waterless ink but is an oilless ink. However, like waterless inks, this ink avoids ink balance problems and it also has environmental benefits.
Heidelberg's inks require a silicon-containing plate to allow the non-imaged areas to repel ink. In addition, it also requires the printer to have a temperature control roll, but instead of a chill roll, this ink needs to heat the roll to 35°C and evaporate the excess water from the ink by heat, when the ink is attached to the plate, the final The total water content is 1%-2%. Although this temperature value is not very strict, it can be varied within the range of 10°C but it must be controlled. If the water evaporates too much, the ink will dry on the ink roller; if the water evaporates too little, the printing plate will tend to be dirty when printed. It is said that the ink will be heated to dry at 40°C, and if dried, it will have water resistance. When the ink is hot enough to dry immediately, no need for dusting (the press is usually done with talcum powder on the newly printed sheet to prevent the ink on the surface of the sheet below the sheet from contaminating the back of the sheet). . After 5 minutes, the degree of drying of the ink allowed the printer to carry the sheet by hand; after 15 minutes, the ink was dry enough to allow the printer to fold the sheet. In addition to the environmental benefits, water-based inks perform as well as the printer expects, have the same viscosity and viscosity as conventional inks, and produce the same maximum solid ink density on the page. At first, its price may be twice that of waterless offset inks now, but in the future its price will depend on the amount of ink produced. (To be continued)
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