MY9700886 Coating, Printing, and Lamination Masafumi Ochi Iwasaki Electric Co., Ltd. 1 Introduction Coating, Printing and Lamination are the major industrial application area for the low energy electron beam accelerator. In this paper some typical applications in this area will be reviewed with the emphasis on the advantages of electron beam accelerator. Also some recent development will be introduced to overview the future trend of the low energy electron beam industry. 2 Low Energy Electron Beam The electron beam with the acceleration voltage up to 300 kV is generally called low energy electron beam. Comparing to the accelerators higher than 300 kV, which is usually composed of a beam scan system, low energy accelerators have a reasonably compact size because of the simplified Selfshield® configuration which prevents any secondary X-ray radiation outside the processor. The penetration property of low energy electron beam is shown in the Fig. 1 in the form of depth-dose curve. As is well known the penetration depth is dependant on the energy of electron and specific gravity of the material. From the figure one can determine the energy of electron required for his application. The low energy electron up to-300 kV usually has a sufficient energy to cope with the most of applications such as coating , printing and lamination in so called the converting industry. 3 Comparison with UV curing and thermal drying The wave length corresponding UV energy ranges from 3 to 10 eV whereas the low energy electron varies from 150 kV to 300 kV, which will be more than 10,000 times higher. This high electron energy will trigger the ionization of polymers causing instant polymerization without the help of photo-initiator or photo-sensitizer which are usually contained in UV resin. Another difference would be the energy utilization aspect. The low energy electron beam processor can utilize more than 60 % of input energy as beam power whereas UV output from a lamp would be less than 20 %of the total lamp input power. On the other hand thermal dryer is basically a very simple system, however, it requires larger equipment space and longer start-up time and has basically lower line speed comparing with the other two. The table 1 shows a comparison to overview the deference of the three technology. To make brief understanding the following characteristics/advantages of low energy electron beam should be noted. 1 requiring no photo-initiator or photo-sensitizer 2 complete polymerization possible 3 hard coating available 4 low level of unreacted residue 5 instantaneous cure 6 high productivity 7 cool cure 8 solvent less resin 9 excellent coating property high gloss - ultra smooth abrasion/scuff resistant excellent adhesion low or no odor low or no extractables stain resistant chemical resistant heat resistant Other advantages associated with machinery .control would be 10 consistent cure 11 lowest energy consumption of the three 12 compact and easy installation 4 Applications and products The typical proven applications and products from all over the world regarding the three area of application, coating, printing, and lamination, whi h is classified according to the process line configuration would be as follows. i P63 Coating 1 Top coat for decorative papers ( USA, Germany, UK) 2 Top coat for decorative packages ( USA ) 3 Top coat for paper bags (USA) 4 Top coat for wood-grain printed papers ( USA ) 5 Top coat on metallized film, papers (USA, Australia) EB-cured base coat applied and cured prior to direct metallizing, and EB-cured topcoat applied and cured after metallizing, to make highly reflective, low cost, printable label stock 6 Top coat for casting paper (USA) 7 Top coat of easy erase white board (Japan) 8 Top coat to upgrade paper ( USA) e.g. kraft, upgraded to a white paper 9 Base coat for metallizing papers, film and non-woven (USA, Belgium) EB-cured base coat and top coat on metallized thermal lining for heat insulation in jacket, etc. 10 Silicon release coating (USA) 11 Magnetic media (Japan) cross-linking/curing iron oxide binder 12 Ceramic tile coating (Japan) art tile ^ 13 Coating on pressure sensitive paper for video printer '-*> (Japan) 14 Anti-static coating (USA) 15 Anti-fog coating (Japan) 16 Adhesive tape and labels (Europe and Japan) 17 Protective film for steel plate (PSA) (Japan) Prin ting 18 Folding cartons (USA, Canada) EB-cured web-offset inks and overprint varnish on SBS(solid bleached sulfate) board for food packaging 19 Flexible packaging (USA) 20 Aseptic packaging (many countries) EB-cured web-offset multi-layer board for aseptic packaging of juice, milk, etc. 21 Printing on plastic sheet or board (Japan) sheet-fed type EB processor EB-cured sheet-offset printed inks and overprint varnish on Polypropylene for table placemat and notebook cover 22 Security printing (USA) Lamination (Adhesive) 23 Coating and laminating of wood products (USA, Europe) EB-cured adhesive between pre-printed paper and MDF board EB-cured high gloss clear coating over the paper for making Ready-to-Assemble furniture 24 Aluminum foil to polyester laminate for radio frequency shielding 25 Paper to paper laminate for playing card (USA) 26 laminating PVC to steel coil (Japan) 27 Laminating film to steel coil (Japan) 28 Flocking (USA) 29 Abrasive (USA) 5 New topics 1 Silicon release resin A Japanese resin manufacturer has newly announced a series of EB curable resin for silicon release coating. The following advantage of the resin were presented... to broaden application to heat sensitive substrate like plastic film or paper, (ambient temperature curing by EB ) high gloss solventless, pollutionless, environment protection to be able to control release property by changing molecular design high speed curing over 300 mpm or 400 mpm energy saving, energy efficient EB cure dose required 20-30 kgy 2 Barrier Film*8) \n improvement of oxygen barrier property of polyolefin film using a electron grafting of silane was reported. A new barrier film made by EB coating and drying process will be expected to make another entry to food and aroma packaging industry. ffc5 6 New trend of Low Energy Accelerator The trend of the low energy EB is going toward the development of the equipment which is (1 )of more compact and of lower cost, (2) of higher productivity, easier installation and higher reliability and (3) the development of various additional new functions to the equipment. The development of extremely low voltage processor might have a possibility to further broaden the utilization of EB technology. The advantage of the extremely low energy(100 - 130 keV) is that it can treat the relatively thin coating without damaging the base substrate such as film and paper. Another issue would be the technic developed to reduce the cost of nitrogen in the free radical induced EB process. One is the nitrogen recirculation system equipped with an automatic oxygen control and the other is the Hybrid Inerting system in which the lower purity level gas from a non cryogenic nitrogen supply is used in conjunction with high purity cryogenically produced nitrogen. 7 Irradiation facility In the expectation of enhancing the use of electron beam converting industry and to meet strong requirement from customers, Iwasaki Electric Co., Ltd. installed a large scale EB production line with the largest working width of 165 cm and high production capacity of 800 Mrad*mpm in June 1993 in Saitama Japan. This line aims at the rental service to customers and the production of customer's products on consignment. The facility has equipped with other auxiliary coating and laminating function. The line abstract is shown in Fg.l 1 and Fig.12. 8 Conclusion Among the various advantage of low energy EB process discussed previously the author would like emphasize on the two points. One is the clean and environmentally friendly aspect in the energy utilization. The EB resin is solventless and free from incinerating and recovering solvents. Another would be energy efficient feature of low energy EB processor which will contribute to ever increasing global requirement of energy savings. In this respect the expectation to the low energy electron beam technology in industry will be further expanding in the near future. Ptfc 9 Acknowledgements The author would like to express special thanks to Mr. P. Michael Fletcher and Fred S. Mclntyre, both from Energy Science Inc. in USA for presenting various EB processed samples worldwide and for the useful suggestions. 10 References 1 Ohba,T. etal, "Electron Beam Curing of Silicone Acrylate for Release Coatings" Proceedings of Radtech Asia '93 , Tokyo Japan: November 10-13,1993 2 Akiyama, A. et al, "New Application of EB Curing to Art Tile" Proceedings of Radtech Asia '93 , Tokyo Japan: November 10-13,1993 3 Shuku, S. et al, "High Quality Recording Media Utilizing EB Cure Process" Proceedings of Radtech Asia '93 . Tokyo Japan: November 10-13,1993 4 Fletcher, P. M. "Low Voltage (120kV) Electron Beam Processor" Proceedings of Radtech Asia '93 , Tokyo Japan: November 10-13,1993 5 Nishikimi, T. et al, "Low Energy EB System" Proceedings of Radtech Asia '93 , Tokyo Japan: November 10-13,1993 6 Kumata, Y. et al, "Development of New Type Low Energy Electron Beam System" Proceedings of Radtech Asia '93 , Tokyo Japan: November 10- 13,1993 7 Nablo, S. V. "Application of Electron Processors in Industry" Proceedings of Radtech Europe "93 : May 2 -6 8 Rangwalla.I. J. et al,"Electron Grafted Barrier Coatings for Packaging Film Modification" 9 Rangwalla, I. J. et al, "Techniques for Optimizing Inerting In Electron Processes" Radiat. phys. Chem. Vol. 42, Nos 1-3, pp.41-45,1993 10 Yoshida.Y "Latest Electron Beam Equipment and its Application" Japanese Magazine "Paper and related Technology", April 1988 11 Yoshida.Y "Introduction of a Large-size EB Production Line" Japanese Magazine "Convertech", December 1993 12 Masuhara.