I. Status Quo In recent years, there has been a drop in fees in the printing industry, and the time period required by customers has been continuously shortened. At the same time, it is also necessary to cope with the rapid development of digitalization. The days of the printing industry are indeed not very good. In such a difficult environment, rotary offset printing has won high-speed development relying on its advantages of high production efficiency, and it has grabbed a 65% strong share in the offset printing market demand.
Now, the biggest issue faced by offset printing is speeding up. Under high-speed printing conditions, the print job characteristics of web offset inks, and the adaptability to paper, web, etc., become particularly important. On the Other hand, environmental protection initiatives in the printing industry are also moving forward with social responsibility and the promotion of ISO14001. In the world-wide wave of environmental protection, how will rotary offset inks handle VOCs (volatile organic compounds), PCA (polycyclic aromatics), heavy metals, industrial waste, and other resources (recycled paper) and combustion (dioxins) in the future? Environmental issues have become important research topics.
Here, the author will focus on the "high-speed printing conditions" and "environmental issues" to talk about the new trend of rotary offset printing ink.
Composition and Properties of Thermoset Web Offset Printing Ink:
Table 1. Composition and properties of lithographic inks Thermoset web offset inks Non-thermoset web offset inks Leaf ink pigments 15-22 15-22 22-22
Synthetic resin 30-35 20-25 25-30
Vegetable oil 5-10 10-15 10-20
Petroleum series solvent 30-40 30-40 25-25
Additive 1 - 5 1 - 5 4 - 10
Total 100 100 100
Viscosity Medium Low Viscosity Medium-Small Medium-Small Large Shrinkage Medium Film Formation Very Slow Slow
Table 1 compares the composition and properties of thermoset web offset inks, non-thermoset web offset inks, and leaf inks. Among them, the basic composition does not have any difference. It is also a pigment, a synthetic resin, a vegetable oil, a refined oil series solvent, and an additive. The difference in the amount of these ingredients is determined by the difference in drying methods and the paper used. The heat-set web offset printing ink is mainly used in an evaporation-drying method. Therefore, compared with other inks, the refined oil series solvent has a lower boiling point and less vegetable oil. This has a great relationship with the on-board stability of the ink to be described later.
Second, speed up measures
1. High Viscosity of Ink On high-speed printing presses, the ink is greatly affected by high loads and mechanical heating. The increase in the temperature of the printing press causes the ink cohesion force on the ink roller and the blanket to decrease, resulting in a drop in the viscosity of the ink. As a result, problems such as coarse dots, insults, residues on the layout and blanket, ink splashes, and ink flying frequently occur.
The high concentration of ink is an effective means to solve the above problems. High concentration generally brings about an increase in the viscosity of the ink, and an increase in the viscosity of the ink will reduce the range of the applicable paper, so it is also indispensable to control the concentration of the ink as much as possible. This problem is also closely related to the "ink emulsification properties" to be discussed later.
2, stability and drying viscosity and speed (rotation number) and stability of the relationship is: with the increase in speed, viscosity increases, ΔTV also becomes larger, which will seriously affect the stability of the ink on the machine, and easily lead to the following as a result of:
1 limited application of paper;
There are residues on the 2 layout and blanket;
3 poor mobility;
4 ink roller deposition;
5 flying ink and so on.
On high-speed printers, the suppression of the second increase in viscosity, which is the so-called "ΔTV rise", is even more important than the increase in the viscosity of the ink itself.
The choice of resin and solvent and the combination of them are an important part of improving the stability of the ink, but this practice usually results in a decrease in the dryness of the ink. From this we can see that the stability and drying of the machine is inherently a contradiction. Therefore, it is an indispensable condition to grasp the balance between the characteristics of the resin and the solvent.
On the other hand, recently, in order to adapt to the trend of higher speed, dryers with a length of 10 meters or more and 4-color zone drying have become the main force of production, and improvements in the mechanical field are also under way.
3, high liquidity and adhesion will bring about the rapid increase in the line speed and cause the printing pressure to drop. In particular, this condition is more pronounced in a single operation, resulting in a decrease in the adhesion and fluidity of the ink. It can be imagined that the impact of close-packing will be even greater.
If the relationship between the viscosity and fluidity of the ink cannot be well balanced, problems such as uneven adhesion, spots, and deposition of the ink roller may occur. From this point of view, the viscosity and fluidity of the ink are also contradictory to each other. It is a very important link to properly balance the proper viscosity and fluidity when designing inks for high-speed printing presses.
4. Emulsification Balance Emulsion balance is one of the most important features related to almost all aspects of printing. Along with the speeding up of printing, it is very important to make accurate predictions by grasping the amount of water in the layout, how the emulsification state on the roller changes, and how viscoelasticity of the emulsified ink is. The viscoelasticity of the emulsified ink is an important factor influencing the ink flowability on the printing press. If the viscoelasticity change of the emulsified ink can be grasped in real time, this has a great influence on the printing applicability of the ink by taking the flowability of the ink as the center. help. For this purpose, the company also independently developed a set of measuring devices for measuring the viscosity of emulsion inks.
Third, the use of environmental countermeasures ink lithography has a long history. Recently, due to the limitation of VOC emissions and its environmental adaptability, soybean oil ink (SOY) has been favored by the industry. In the United States, soy oil inks are gradually replacing mineral oils that use condensing rotary offset color inks and are used in newspapers, telephone books, and other printing.
In addition, ink manufacturers in Japan almost all began to use the ink solvent to remove the aromatic (less than 1%) AF solvent.
1. Environment-friendly product certification standards This standard is the standard that the Japan Environmental Association evaluates products that make a great contribution to the field of environmental protection. Among them, the following regulations are made for inks:
The aromatic content in the solvent used is 1 or less.
2 Ink complies with NL (Regulations for printing inks for food packaging materials).
3 The ink consumes no significant increase in energy during manufacture and use.
4 The effect of the deinking on the environment is not greater than that of previous products.
2. Soybean Ink Recognition Standard This standard was developed by the American Soybean Oil Association for the popularization of soybean oil. The soybean oil used in Table 3 is approved by it.
Table 3: Identification Standards for Soybean Ink Leaf Paper Ink Offset Offset Printing Newspaper Newspaper Soybean Oil 20% 7% Ink 40%, Other 3 Colors 30%
3. Recycled paper countermeasures With the progress of deinking technology and the need for environmental protection, the utilization rate of recycled paper is increasing. However, there are no doubts about the defects of recycled paper, such as weak surface strength, poor moisture resistance (weak surface hardness in wet state, easy hair removal, sticky rollers). These recycled papers often make the blankets full of dust, causing picture pollution. Therefore, in the future, starting from the ink aspect, the development of "low viscosity, high viscoelasticity inks" with "highly soluble varnish made of polymer materials" has become a prominent requirement in the printing industry.
5. Burning of printed materials and dioxin pollution Recently, dioxin pollution caused by incineration has gradually become a social problem. Including the ink manufacturers, there are still many unclear places for the production of dioxins. From the situation that has been mastered can be summarized as the following:
1 The lithographic ink uses raw materials that are completely free of dioxins.
2 Chlorine-free materials do not produce dioxin when burned. Chlorine-containing materials can inhibit the production of dioxins when burned under proper conditions.
Some of the raw materials used for the 3 lithographic ink contain chlorine compounds, and the external printing paper also contains trace amounts of chlorine.
4 There is a close relationship between the burning conditions and the production of dioxins. Therefore, the Japanese government called on all manufacturers to strictly abide by the standards for waste incineration and the standards for pollutants stipulated in the Waste Disposal Act and the Air Pollution Control Act, which were issued on August 29, 1997 and began on December 1, the same year. .
As shown above, although dioxin pollution cannot be expressed in terms of specific figures, it can be seen that the use of lithographic printing inks is much less harmful than ordinary household waste.
At this stage, the development trend of thermosetting web offset printing in Japan is good. However, along with the progress of high-speed processes and the development of environmental requirements, it is also facing a severe test. In short, accurately grasping issues and responding quickly in the future is an important task for the industry to follow.
Now, the biggest issue faced by offset printing is speeding up. Under high-speed printing conditions, the print job characteristics of web offset inks, and the adaptability to paper, web, etc., become particularly important. On the Other hand, environmental protection initiatives in the printing industry are also moving forward with social responsibility and the promotion of ISO14001. In the world-wide wave of environmental protection, how will rotary offset inks handle VOCs (volatile organic compounds), PCA (polycyclic aromatics), heavy metals, industrial waste, and other resources (recycled paper) and combustion (dioxins) in the future? Environmental issues have become important research topics.
Here, the author will focus on the "high-speed printing conditions" and "environmental issues" to talk about the new trend of rotary offset printing ink.
Composition and Properties of Thermoset Web Offset Printing Ink:
Table 1. Composition and properties of lithographic inks Thermoset web offset inks Non-thermoset web offset inks Leaf ink pigments 15-22 15-22 22-22
Synthetic resin 30-35 20-25 25-30
Vegetable oil 5-10 10-15 10-20
Petroleum series solvent 30-40 30-40 25-25
Additive 1 - 5 1 - 5 4 - 10
Total 100 100 100
Viscosity Medium Low Viscosity Medium-Small Medium-Small Large Shrinkage Medium Film Formation Very Slow Slow
Table 1 compares the composition and properties of thermoset web offset inks, non-thermoset web offset inks, and leaf inks. Among them, the basic composition does not have any difference. It is also a pigment, a synthetic resin, a vegetable oil, a refined oil series solvent, and an additive. The difference in the amount of these ingredients is determined by the difference in drying methods and the paper used. The heat-set web offset printing ink is mainly used in an evaporation-drying method. Therefore, compared with other inks, the refined oil series solvent has a lower boiling point and less vegetable oil. This has a great relationship with the on-board stability of the ink to be described later.
Second, speed up measures
1. High Viscosity of Ink On high-speed printing presses, the ink is greatly affected by high loads and mechanical heating. The increase in the temperature of the printing press causes the ink cohesion force on the ink roller and the blanket to decrease, resulting in a drop in the viscosity of the ink. As a result, problems such as coarse dots, insults, residues on the layout and blanket, ink splashes, and ink flying frequently occur.
The high concentration of ink is an effective means to solve the above problems. High concentration generally brings about an increase in the viscosity of the ink, and an increase in the viscosity of the ink will reduce the range of the applicable paper, so it is also indispensable to control the concentration of the ink as much as possible. This problem is also closely related to the "ink emulsification properties" to be discussed later.
2, stability and drying viscosity and speed (rotation number) and stability of the relationship is: with the increase in speed, viscosity increases, ΔTV also becomes larger, which will seriously affect the stability of the ink on the machine, and easily lead to the following as a result of:
1 limited application of paper;
There are residues on the 2 layout and blanket;
3 poor mobility;
4 ink roller deposition;
5 flying ink and so on.
On high-speed printers, the suppression of the second increase in viscosity, which is the so-called "ΔTV rise", is even more important than the increase in the viscosity of the ink itself.
The choice of resin and solvent and the combination of them are an important part of improving the stability of the ink, but this practice usually results in a decrease in the dryness of the ink. From this we can see that the stability and drying of the machine is inherently a contradiction. Therefore, it is an indispensable condition to grasp the balance between the characteristics of the resin and the solvent.
On the other hand, recently, in order to adapt to the trend of higher speed, dryers with a length of 10 meters or more and 4-color zone drying have become the main force of production, and improvements in the mechanical field are also under way.
3, high liquidity and adhesion will bring about the rapid increase in the line speed and cause the printing pressure to drop. In particular, this condition is more pronounced in a single operation, resulting in a decrease in the adhesion and fluidity of the ink. It can be imagined that the impact of close-packing will be even greater.
If the relationship between the viscosity and fluidity of the ink cannot be well balanced, problems such as uneven adhesion, spots, and deposition of the ink roller may occur. From this point of view, the viscosity and fluidity of the ink are also contradictory to each other. It is a very important link to properly balance the proper viscosity and fluidity when designing inks for high-speed printing presses.
4. Emulsification Balance Emulsion balance is one of the most important features related to almost all aspects of printing. Along with the speeding up of printing, it is very important to make accurate predictions by grasping the amount of water in the layout, how the emulsification state on the roller changes, and how viscoelasticity of the emulsified ink is. The viscoelasticity of the emulsified ink is an important factor influencing the ink flowability on the printing press. If the viscoelasticity change of the emulsified ink can be grasped in real time, this has a great influence on the printing applicability of the ink by taking the flowability of the ink as the center. help. For this purpose, the company also independently developed a set of measuring devices for measuring the viscosity of emulsion inks.
Third, the use of environmental countermeasures ink lithography has a long history. Recently, due to the limitation of VOC emissions and its environmental adaptability, soybean oil ink (SOY) has been favored by the industry. In the United States, soy oil inks are gradually replacing mineral oils that use condensing rotary offset color inks and are used in newspapers, telephone books, and other printing.
In addition, ink manufacturers in Japan almost all began to use the ink solvent to remove the aromatic (less than 1%) AF solvent.
1. Environment-friendly product certification standards This standard is the standard that the Japan Environmental Association evaluates products that make a great contribution to the field of environmental protection. Among them, the following regulations are made for inks:
The aromatic content in the solvent used is 1 or less.
2 Ink complies with NL (Regulations for printing inks for food packaging materials).
3 The ink consumes no significant increase in energy during manufacture and use.
4 The effect of the deinking on the environment is not greater than that of previous products.
2. Soybean Ink Recognition Standard This standard was developed by the American Soybean Oil Association for the popularization of soybean oil. The soybean oil used in Table 3 is approved by it.
Table 3: Identification Standards for Soybean Ink Leaf Paper Ink Offset Offset Printing Newspaper Newspaper Soybean Oil 20% 7% Ink 40%, Other 3 Colors 30%
3. Recycled paper countermeasures With the progress of deinking technology and the need for environmental protection, the utilization rate of recycled paper is increasing. However, there are no doubts about the defects of recycled paper, such as weak surface strength, poor moisture resistance (weak surface hardness in wet state, easy hair removal, sticky rollers). These recycled papers often make the blankets full of dust, causing picture pollution. Therefore, in the future, starting from the ink aspect, the development of "low viscosity, high viscoelasticity inks" with "highly soluble varnish made of polymer materials" has become a prominent requirement in the printing industry.
5. Burning of printed materials and dioxin pollution Recently, dioxin pollution caused by incineration has gradually become a social problem. Including the ink manufacturers, there are still many unclear places for the production of dioxins. From the situation that has been mastered can be summarized as the following:
1 The lithographic ink uses raw materials that are completely free of dioxins.
2 Chlorine-free materials do not produce dioxin when burned. Chlorine-containing materials can inhibit the production of dioxins when burned under proper conditions.
Some of the raw materials used for the 3 lithographic ink contain chlorine compounds, and the external printing paper also contains trace amounts of chlorine.
4 There is a close relationship between the burning conditions and the production of dioxins. Therefore, the Japanese government called on all manufacturers to strictly abide by the standards for waste incineration and the standards for pollutants stipulated in the Waste Disposal Act and the Air Pollution Control Act, which were issued on August 29, 1997 and began on December 1, the same year. .
As shown above, although dioxin pollution cannot be expressed in terms of specific figures, it can be seen that the use of lithographic printing inks is much less harmful than ordinary household waste.
At this stage, the development trend of thermosetting web offset printing in Japan is good. However, along with the progress of high-speed processes and the development of environmental requirements, it is also facing a severe test. In short, accurately grasping issues and responding quickly in the future is an important task for the industry to follow.
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