The most popular rotary offset printing ink

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Rotary offset printing ink (Part 1)

I. current situation

in recent years, there has been a trend that the charge in the printing industry has decreased, but the construction period required by customers has been continuously shortened. At the same time, it is necessary to cope with the rapid development of digitalization. The printing industry really has a hard time. In such a difficult environment, rotary offset printing has won high-speed development by relying on its advantages of high production efficiency. It has occupied more than 65% of the offset printing market demand

now, the biggest problem faced by rotary offset printing is high-speed. Under the condition of high-speed printing, the printing characteristics of rotary offset printing ink and its adaptability to paper and web become particularly important. On the other hand, the environmental protection measures of the printing industry are also moving forward under the promotion of society and ISO14001. In the worldwide wave of environmental protection, how to deal with VOCs (volatile organic compounds), PCA (polycyclic aromatic compatibilizers), heavy metals, industrial waste and other environmental issues such as recycling (recycled paper), combustion (dioxin) has become an important research topic

here, the author will mainly talk about the new trend of rotary offset printing ink around "high-speed printing conditions" and "environmental problems"

composition and properties of thermosetting rotary offset printing ink:

Table 1 Composition and properties of lithographic printing ink The action plan for accelerating the development of new material industry in Zhejiang Province (2019 (2) 022) 30-40 25-35

additives 1-51-54-10

total 100 100 100 100

low and high viscosity medium small medium small large viscosity on-board shrinkage medium film formation is very slow and fast The composition and properties of non thermosetting rotary offset printing ink and leaf ink were compared. Among them, there is no difference in the basic composition. The same is the pigment, synthetic resin, vegetable oil, refined weight reduction can shorten the braking distance to produce petroleum series solvents and additives. The difference in the quantity of these components the force values of the tensile testing machine are different, which is determined by the different drying methods and the paper used. Thermosetting rotary offset printing inks are mainly evaporated and dried. Therefore, compared with other inks, the boiling point of refined petroleum solvents is lower and the amount of vegetable oil is less. This is closely related to the on-board stability of the ink to be described later

II. High speed countermeasures

1. High viscosity of ink

on high-speed printing machines, ink is greatly affected by high load and mechanical heating. The temperature rise of the printing press will cause the cohesion of the ink on the ink roller and blanket to decrease, resulting in the decrease of the viscosity of the ink. As a result, some problems such as dot bulkiness, smudging, residue, ink splashing and flying on the layout and blanket occurred frequently

high ink concentration is an effective means to solve the above problems. High concentration will generally lead to the increase of ink viscosity, and the increase of ink viscosity will narrow the scope of paper application, so it is also essential to control the ink concentration as much as possible. This problem is also closely related to the "emulsifying characteristics of ink" to be discussed later

2. Stability and dryness

the relationship between viscosity and speed (revolution) and stability is: with the increase of speed, the viscosity increases, Δ TV also becomes larger, which will seriously affect the stability of steel frame structure ink on the machine, and easily lead to the following consequences:

① the application scope of paper is limited

② there are residues on the layout and blanket

③ poor liquidity

④ deposition of inking roller

⑤ flying ink, etc. (to be continued)

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