EB curing technology

The company installed an EB curing device behind the gravure Cerutti printing unit, so here I would like to share some of the knowledge I have about EB curing technology with you.

EB curing technology is a new curing technology that can effectively control air pollution, especially volatile organic compounds (VOC) emissions. The curing mechanism is the electron beam EB (Electron Beam) irradiation of solvent-free liquid chemicals, so that a rapid polymerization reaction, resulting in a three-dimensional network structure and the formation of a solid film. As it basically achieves "zero emissions in sustainable development," it is increasingly favored by people.

principle

EB curing is a form of radiation curing. It is a process in which an electron beam is used as a radiation source to induce the rapid conversion of a specially formulated 100% reactive liquid to a solid. The principle is: First, high-energy electrons interact with ink molecules to decompose into free radicals; then, the free radicals react with C=C double bonds to form growth chains; finally, the growth chain and the rest of the paint or ink components The reaction causes cross-linking of the cured coating, and the cross-linking density increases. Due to the high electron energy of the irradiation, the above reaction is often accompanied by molecular degradation. Molecular ion rearrangements and other negative reactions. The EB-cured coating thus produced greater branching and higher crosslink density.

EB curing requires dedicated curing equipment. The main body of the curing device is an electron curtain accelerator structure. Its working principle is that after electrons are emitted from a set of linear cathode plates, they are accelerated by a vertical uniform electric field, and a curtain electron beam is obtained under the accelerator radiation box. Since the irradiated product is close to the electric field, its accelerating voltage is not high (below 500 kV), but the power is high due to the large output current. The linear cathode gun is far more compact than the scanning device, and it is easier to install on the production line and also easier to shield.

Features

As a new type of curing technology, EB curing has unique advantages over traditional curing techniques.

(1) The printing energy required for curing ranges from 150 to 300 keV. It reaches the surface of the cured material at a speed close to the speed of light and is not only limited by the color of the coating, but it also cures the adhesive between paper and other substrate internal coatings and opaque substrates such as aluminum foil.
(2) EB curing allows 100% curing of inks and adhesives, especially in areas where the degree of cure must be 100%, such as food packaging.
(3) Low energy consumption, 5% of EB curing energy is 5% for UV curing, and 1% for traditional thermal curing.
(4) Simple operation, easy control, high accuracy and repeatability, no environmental pollution.

Application prospects in the printing field

EB ink (varnish) has many advantages, making EB curing technology show strong vitality in the future development.

(1) It contains no volatile substance VOC, has no odor or only a small odor, reduces the harm to the health of workers, and has no environmental pollution.
(2) Good resistance, since the chemical substances in the ink form a polymer three-dimensional network polymer through cross-linking reaction, the ink film has good chemical resistance and friction resistance.
(3) The curing time is short, generally only 0.1 seconds can be completely dry, compared with the traditional printing takes several minutes or even several days to completely dry, compared to greatly improve the production efficiency, is conducive to the scale of production.
(4) The pigment concentration is high, the printed product has a beautiful appearance, and has a strong glossiness and three-dimensionality.
(5) Reduce the cleaning time of the printing press.
(6) There is no strong heat that causes the substrate to deform when cured.

Of course, as a new developing curing technology, EB curing technology also has some shortcomings. For example, in recent years, although EB curing equipment has been greatly reduced in price, its one-time investment in equipment is still relatively large; the price of EB ink is still higher than the price of ordinary ink; EB curing is only suitable for flat coating curing. Thus, the geometry of the cured product is limited; an important feature of the EB ink is that it has good resistance, but this is a factor that makes deinking difficult and hindering recycling when the waste print is recycled.
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In short, the application of EB curing technology in the packaging and printing industry is promising. In order to make the printing and curing process more convenient and economical, it is necessary to actively develop a low-cost, compact EB curing device, and improve the transmission device so that the product can be rotated and cured so that the radiation curing can be applied to various shapes of products. It can be asserted that EB curing technology will have greater development in the future due to its low pollution, low energy consumption, and high quality.

Reprinted from: Jin Jia Cai Yin Song Liwei