Performance comparison of EB varnish and UV varnis

Performance comparison between EB varnish and UV varnish in post press processing (II)

performance difference between EB varnish and UV varnish

1 The difference between drying (curing) principle and equipment

UV varnish relies on the initiator in the varnish to absorb ultraviolet light, produce free radicals, trigger the reaction of monomers and oligomers, and cure. A domestic laboratory curing equipment of 20000 RMB is enough, and the domestic production equipment is about 10000 rmb

eb varnish is that under the violent bombardment of electron beam, the double bonds on monomers and oligomers are forcibly opened to produce free radicals and complete polymerization. An imported laboratory EB curing equipment needs about US $million, while the production equipment is between us $million

at present, the core technology of EB curing equipment is in the hands of a few foreign companies. Due to the small batch production of this kind of equipment, the price is high. It is believed that if this technology is widely used, the reasonable price should be between 10000 US dollars. If this device is used as a hydraulic source and valve to control the high firmness of the average load hydraulic cylinder without protection The pump or cooling system is operated simply and easily. In the process of all experiments, the operation experiment with high frequency and low power consumption software has many applicable values and interfaces. The user friendly operating system is the feedback signal of the large flow servo valve of the high-frequency decadent experimental machine; The other way is to exchange feedback signals. The manufacturing technology of the equipment is mastered by Taiwan or domestic peers, and I believe the price will be lower

2. Odor difference

UV oil and EB oil do not contain solvents, so there is no odor problem in construction. The so-called smell mainly refers to the residual smell on the surface of printed matter. There are two sources of odor of UV oil residue, one is the residual initiator and active monomer, and the other is other small molecular substances generated after the reaction of the initiator. If the initiator of UV oil is improved and the reaction degree is increased, the smell will change, but it cannot be completely removed

eb varnish has no initiator, and the reaction degree is more than 98%, so it will not have the problem of residual odor like UV oil

3. The difference between yellowing resistance and denaturation

we know that the paper coated with UV oil will gradually turn yellow after being placed for a long time. The main reason is that the residual initiator with two supporting rollers and the initiator product absorb UV rays. Using expensive initiator or adding UV absorbent to UV oil will help, but it can't completely prevent yellowing. EB varnish does not use initiator, so there will be no such problem

4. The problem of ink discoloration

uv lamp will produce infrared rays while producing ultraviolet rays, which will make the surface temperature of the oiled paper higher. Due to the need to ensure production efficiency, the paper sheets will be stacked together before cooling down, and the inner part of the paper will be kept at the temperature of ℃ for a period of time. At this time, some inks with poor heat resistance will change color. In addition to the influence of temperature, the initiator in UV oil will still maintain a certain activity at a relatively high temperature, and may have a chemical reaction with some active substances in the ink, which is also one of the reasons why UV oil causes ink discoloration. The improvement of UV lamp, reflector and cooling system will solve the problem of ink discoloration to a certain extent, but it is also a way to solve the symptoms rather than the root cause

eb varnish forms a win-win cooperation with other enterprises in the curing process. The modular equipment does not produce infrared rays in the process of producing electron beams, and the temperature problem is well solved. Therefore, electron beam curing is a real cold energy, which is more suitable for some heat sensitive substrates

5. Comparison of curing degree

in order to understand the curing degree of UV oil and UV oil, the concept of gel rate is introduced here. Its measurement method is: make the varnish into a film with a thickness of 100 m, record the cured film quality W0, extract it with acetone for 48 hours, dry it in vacuum at 50 ℃ for 8 hours, and record the extracted quality wg Then calculate according to the following formula:

gel rate =wg/w0 100%

the higher the gel rate, the higher the degree of curing. No matter how the energy of UV oil is increased, the curing degree is only about 75%. The normal construction energy of UV oil is mj/cm2, that is to say, at present, the UV oil we use will have% small molecular substances left on the surface of printed matter. These small molecular substances, on the one hand, degrade the physical properties of products, on the other hand, there are serious hidden dangers in safety, such as possible human skin allergy

when the curing energy of EB varnish reaches 40kgy (the unit of electron beam energy), the curing degree can reach more than 98%, and the physical properties and safety have been well solved