The head of offset printing ink technology of the printing material company has been engaged in the printing industry for many years, and is responsible for solving printing technology problems for customers and has in-depth knowledge of printing consumables such as ink and fountain solution.
Many printing customers are also interested in green inks, and they are very concerned about whether this ink will become the market-leading future. The following questions and answers may increase everyone's understanding of environmental inks and find inspiration from them.
1. Are the inks available in the market "standard in lead content"?
The first thing to define is what the standard is. EN71? ASTM? Or other standards? Both EN71 and ASTM are relatively common standards, but there are actually many others (for example, 94/62/EC and EU ROHS, etc.). Some of the strict requirements not only test the lead content of the ink, but also take the entire box for testing.
The "lead content" is just a general term. In fact, it should be the correct content of heavy metals, including: lead, antimony, arsenic, arsenic, barium, cadmium, chromium, There are eight types of Mercury and Selenium.
There are two more interesting facts:
i. Metallic inks, such as gold inks and silver inks, are of a standard heavy metal content.
Ii. The heavy metal content of most printing inks is standard and not just environmentally friendly.
2. What is the difference between environmental inks and common inks?
To answer this question, first understand the composition of the ink. The ink is caused by pigments, additives (e.g. driers), resins, alkyd alkyds and oils (e.g. mineral oil, soybean oil, flaxseed oil).
The environment-friendly ink means that in the ink formulation, the components of the oil are vegetable oils, such as soybean oil, flaxseed oil, and other natural oils. The names are Bio, Soy, Eco and Oko.
Other aspects are no different from ordinary ink.
What customers are most concerned about is the hue. Is the hue printed with eco-friendly ink the same as ordinary ink? The answer is the same, or even better. Because of the use of natural oils, pigments are more capable of expressing colors in environmentally friendly inks, and are more easily achieved when the ink balance is adjusted.
3. Where are the various types of environmentally friendly inks?
Most of the green inks available on the market are named after the raw materials, such as: Bio, Soy, Eco, Oko, etc.
It is only the proportion of vegetable oil used. The definition of Soy ink is that 20-30% of the flat ink components contain soybean oil and the others are mineral oil. Bio ink is defined as completely free of mineral oil, ie 100% is vegetable oil.
4. Will the price of environmental protection ink be very expensive?
Basically, the price of environmental protection ink is about the same as ordinary ink.
Because natural oils (such as flaxseed oil) are all abundant resources, unlike crude oil/mineral oil, there is a certain limit and the price will not be too volatile.
5. Is there ample supply of environmentally friendly ink? Will it be out of stock?
In fact, environmental inks (such as: Bio ink) have been in Europe for more than 15 years and are produced and supplied just like normal inks. Some manufacturers will go in the direction of environmental protection when producing new series of inks, so supply will not be a problem.
6. Are there eco-friendly ink fountain inks or printing inks?
There are 100% vegetable inks used in printing ink and printing ink oil supply, mainly European brands.
7. Will there be any problems with the use of environmentally friendly inks and diversion of common inks?
Eco-friendly inks can be applied to any printing press without any modifications or special cleaning agents. Basically, customers can fully use environmentally-friendly inks. Even if the ink is to be converted, the process is the same as ordinary inks.
In summary, most users or manufacturers have used inks containing vegetable oils as environmentally friendly inks. Naturally, it is a matter of course that heavy metal content should meet international standards.
In fact, one of the more important is the content of Volatile Organic Compound (VOC). VOCs are volatile organic compounds that pollute the air and cause great harm to humans. The EPD is drafting legislation to regulate the VOC content in printing inks.
In the future, we will consider this when purchasing green printing inks. â—Ž
Paper mill experts help you analyze paper printing problems
November 02, 2006 8:46 Source: HC360 Printing Industry Channel User Comments 0 Article Go to Forum
Print off the powder. In printing, due to the external force, the paper surface coating, fibers or dust are pulled up by the blanket, or the impurities in the ink path are transferred to the blanket, resulting in that the local graphics and text cannot be properly transferred to the paper, which seriously affects the quality of the finished product. A printing phenomenon.
In offset printing, printing out of powder is one of several quality issues that can easily occur. It has caused major problems for printing plants and paper mills. For this reason, printing plants and paper mills have to avoid falling powder. A lot of work, but it can not be completely eliminated from the paper and printing.
How to deal with if powder falls? From the point of view of the paper mill, we have taken many measures in the production process to avoid the occurrence of powder falling, such as improving the surface strength of the paper and increasing the rewinder dust collection device. Improve the frequency of cutter replacement, and achieved better results.
In terms of printing plants, for paper that has fallen out of powder, how do we adjust the printing process and conditions to reduce and avoid the problem of powder dropping? Through our experience in dealing with guest complaints for many years and the results of communicating with customers, Aiming at the problem of powder falling in different states, we made a summary of how to take remedial measures from the printing process after the cause and the occurrence of powder failure. We hope that we can share it with the printing factory. Please correct me.
First define two nouns: the original point and the transfer point. The original point is the first spot on the printed sheet where the powder falling problem occurred, and there is no ink in the middle. The transfer point, which is the spot generated on the subsequent print, has an irregular ring shape with ink in the middle.
Catheter section
The catheter section is a non-fibrous material that cannot be completely removed from the pulp. It is relatively brittle, hard, and has a relatively small binding force with the fibers and the paint. When exposed to external forces, it is relatively easy to be pulled up. His appearance is more regular, irregular rectangular or square, about 1mm in size.
In the printing, if you find that the printout is in the form of a catheter section, the following methods may be taken and may be improved:
â— reduce the corresponding ink viscosity;
â— Reduce the printing speed;
â— increase the cleaning blanket frequency;
â— Replace the new blanket;
â— Reduce the printing pressure of the pink sequence, increase the printing pressure of the previous color sequence;
â— First print the base paper with varnish, stick the catheter section, and then print normally.
2. Powder removal
Destaining is due to the coating between the surface of the paper. The binding force between the coating and the fiber is insufficient, and a powder off phenomenon occurs when the coating is pulled up during printing. Its status is irregular.
The reasons for this type of powder dropping may be related to the lack of surface strength in terms of paper; from the printing point of view, it may be related to factors such as excessive ink viscosity, excessive printing pressure, and excessive printing speed.
The phenomenon of powder falling, such as de-dusting, can be taken as the above-mentioned method of handling off-powder of the catheter section type, and may be improved to some extent.
3. Paper powder
If paper paper powder adheres to the surface of the paper, it adheres to the blanket when printing, which may cause the graphic part to not be normally transferred to the surface of the paper to form spots. The shape of the paper is irregular fibrous.
The reason for the generation of paper powder is mainly due to the fact that the cutting knife is relatively blunt. When cutting, it is not the fact that the fiber is cut but it is pulled off. At the same time, part of the fiber is pulled out onto the paper. Under normal circumstances, this type of powder drop appears on the four sides of the printed matter, and the dragging part is the most serious. To determine if there is any paper powder on the paper, use a dry black cloth to wipe the surface of the paper and see if there is a white powder on it. If yes, it means that there is paper powder on the paper, and vice versa.
It was found that there was paper paper powder on the paper, which could be printed on the monochrome machine first, sticking the paper paper powder off, and then printing normally, which would greatly improve. If the printing company cuts itself, it is necessary to shorten the grinding cycle and avoid the generation of paper powder.
4. Mexican skin
If the ink dries the skin. Foreign matter in the ink or the water system is contaminated to produce foreign matter. Adhesion to the printing plate or blanket during the printing process can also cause spots on the print. On this type of powdered print, no original point was found, and the paper coating was not damaged. The spots were all transfer point shapes. For this type of powder dropping, the ink path and water path must be thoroughly cleaned, including the ink tank sink and the transfer roller group of the transfer roller group. Plates and blankets, then replace the new ink and fountain solution.
For the above types of powder, if you can not accurately determine which type belongs to the spot pattern on the print, you can also use the transparent tape to stick the foreign material on the blanket and observe the shape and composition under the microscope. Confirm the specific reasons, and take corresponding countermeasures to reduce the occurrence of powder falling problems and minimize the loss for different types.
Source: Graphic Arts Author: Yung Wei