The most popular way to control the pressure betwe

There are many factors that can cause ink scaling by controlling the pressure between ink rollers, but they can be summed up as follows: the content of dry oil in ink is too high; Due to temperature; Due to long-term contact between ink and air. Let's do some analysis below

1. The dry oil content in the ink is too high

generally, such mistakes may occur in the process of ink manufacturing or printing. Adding desiccant must be combined with printing conditions and ambient temperature to add an appropriate amount, otherwise the ink will dry when you don't want it to dry (crusting). As for the use of desiccant, it will not be repeated here

2. Due to temperature, the scaling of ink caused by temperature is mainly caused by high temperature. When the temperature is too high, the activity of unsaturated molecules in the ink increases, especially in aerospace. The part of the surface in contact with air is easier to oxidize the conjunctiva under the action of oxygen. The high temperature mentioned here has the following aspects:

A) the ambient temperature is too high. According to our experience, the scaling phenomenon of ink in summer is much more obvious than that in winter, especially if there is no air conditioning in the workshop. It is necessary to reasonably control the temperature of the working environment. Generally speaking, it is an ideal temperature to control the temperature of the workshop at about 20 ℃, which can not only ensure the good fluidity and transfer performance of the ink, but also control the scaling of the ink at a relatively low level

b) when the temperature on the machine (such as between ink rollers) is too high, the ink will also appear skinning in the printing process. When the contact pressure between the ink rollers is too high, the temperature rises obviously, and the ink is easy to appear skinning on the ink bucket and the ink roller at this time

accurately adjusting and controlling the pressure between ink rollers is important to prevent ink from printing in the process of printing It is of great significance to select a suitable clamp and install it on the tension machine, and conduct a pre experiment to confirm the most suitable clamp and clamp type

c) the air leaked from the dryer dries the surface of the ink, or the hot air blows the ink into the ink bucket

d) and other abnormal temperature rise of the machine

3. Because the ink is in contact with the air for a long time, the binder component in the ink can react with the oxygen in the air. If it is exposed to the air for a long time, it will be oxidized and skinned. Generally, there are the following kinds of Crusts:

A) the temporarily unused ink will appear a thick oxide film on the surface after being exposed in the air for a long time. We all have such experience in printing plants. When filling ink from the ink cartridge or ink bucket, we should try to keep the surface of the ink flat. The reason for doing so is to minimize the contact area between the ink and the air, so that the waste of ink will be as small as possible even after the ink is filmed. Then cover the remaining ink with a protective film to block the contact with the air, which can also effectively prevent the scaling of the ink

b) when the printer was shut down for a long time, the ink path was not cleaned, resulting in ink scaling in the ink roller and ink bucket. Be sure to clean the ink path when the machine is shut down for a long time. When the downtime is not very long, you can choose to spray ink anti scaling agent on the ink path

c) if the ink is not stirred in the ink bucket for a long time, there will be scaling. In the printing process, we often say that it is very important to stir the ink in the ink bucket frequently. Firstly, it can maintain the good fluidity of the ink in the ink bucket. Secondly, doing so can make the surface ink and the internal ink exchange frequently, and avoid that the ink in contact with the air is always the same part. For the standardized operation of ink supply adjustment, the basic principle of ink supply adjustment is: the gap between the ink bucket blade and the ink bucket roller is as small as possible, and the angle of the ink bucket roller is as large as possible. This has laid the foundation for the large-scale production of plastic products for automobile and aerospace, and it is partly based on the above considerations

d) the ink roller structure is not good, resulting in a stagnant part. As mentioned in B, this will also lead to a part of the ink always in contact with the air, so skinning is inevitable

how to effectively deal with the problem of ink scaling in printing? The following methods are commonly used in printing operations

(1) do not use ink that dries too fast; (2) Add additives such as slow drying solvent; (3) Replace the deteriorated ink with less oil and bubbles; (4) Keep stirring in the ink bucket; (5) A closed top cover is arranged on the ink fountain; (6) Adjust the hot blowing angle. Anyone with a little knowledge of printing knows that when the drying is too fast, the ink concentration is too light, the flow is poor, the ink thixotropy is large, or the ink is static, the speed of the printing machine is adjusted faster, which not only prevents the ink from drying on the printing plate in advance, but also overcomes the crust formed by the ink of packaging printing ink, and also eliminates the speckle fault of graphics and texts