In offset printing, there are many reasons for the formation of the ink layer, but the following are the main points: the excessive content of dry oil in the offset printing ink leads to the crust formation; the high temperature causes the offset printing ink crust; the offset printing ink surface and the air contact for a long time cause skin formation.
Such errors may occur in the process of making offset ink or in the process of printing. Add desiccant must combine with printing conditions and ambient temperature. Otherwise, offset ink will dry (crust) when you don't want to dry.
Offset ink crust caused by high temperature
The crust of offset ink caused by temperature is mainly caused by high temperature. When the temperature is too high, the activity of unsaturated molecules in offset printing ink is enhanced, especially the surface air contacting part is easier to oxidize conjunctiva under the action of oxygen.
A, the ambient temperature is too high. According to our experience, the phenomenon of skin sticking of offset ink in summer is much more obvious than that in winter. If there is no air-conditioning in the workshop, it will be more obvious. Reasonable control of environment temperature is necessary, in general the workshop temperature control at 20 degrees Celsius is the ideal temperature, which can ensure good fluidity and offset printing ink transfer performance, and can be offset printing ink crust in a low degree.
B, when the machine (such as rollers) high temperature will also make offset printing ink crust phenomenon in the process of printing. When when the contact pressure between the roller, temperature rise is obvious, it is very easy in the offset printing ink fountain roller and crust phenomenon. The regulation and control of the pressure between the rollers accurately, to prevent the offset printing ink in the printing process of crust is very important.
C, the drier from escaping air dry offset printing ink surface, or hot air to offset ink fountain in the.
Offset printing ink, printing ink and -003.jpg3 ink skin surface air long time to contact crust
The linking components in offset printing ink can react with oxygen in air, and exposed for a long time in air, of course, it will be oxidized and form crust phenomenon. In general, this kind of crust is mainly the following:
A, temporarily unused offset ink, exposed in the air, a long surface will appear thick oxide film. The printing plant will have such experience, when from the cartridge or when the ink barrel outward containing ink to the surface, offset printing ink to keep a flat state, the reason is to reduce the contact area of the ink and air, so even if the ink conjunctival waste after will be as small as possible. Then the remaining offset ink is rebuilt with a protective film to block contact with the air, which can also effectively prevent the printing of offset ink.
B, printing machine downtime, no cleaning ink, offset ink and ink fountain roller in the cause in the crust. In the work must pay attention to when longer downtime, to be offset printing ink cleaning, when the stop time not too long, you can choose to spray ink in the ink on the anti skinning agent.
C, offset printing ink in the ink fountain if the long time does not stir, there will be crust. In the printing process we often talk about "three ground" which often stir ink in the ink fountain is a very important one, first of all it can to maintain liquidity in an offset printing ink is very good, then this can make the surface of the ink and the ink inside the regular exchange, avoid contact with air and ink is always the same part. Standardized operation regulation for the amount of ink, ink for the basic principles of regulation: the gap between the blade and the ink fountain roller is as small as possible, the angle of the ink fountain roller is as large as possible. There is also a part of this reason that is based on the above considerations.
D, the roller structure is not good, not the flow produced by retention.
How to deal with and solve the malfunction of offset printing ink effectively in printing?
1, can not use dry too fast offset ink;
2, slow dry solvent and other additives;
3, replace the already deteriorated offset ink;
4, stirring in the ink fountain in stop;
In 5, the fountain set on a closed roof;
6, adjust the angle of the heat blow. A little common sense knows that when printing ink drying too fast, too short, poor fluidity, concentration of printing ink or ink electrostatic printing machine, will speed up, which prevent the offset printing ink on the printing plate drying in advance, and overcome the packaging printing ink into ink crust formation, but also eliminate the fault pattern markings.