| The extrusion-coated paperboard tray packaging which contains a tray container and a piece of lidding film is widely used along with MAP technology in fresh food packaging industry. Much research has been done on perforation onto lidding film. This research is based on the attempt of perforating on the tray materials: uncoated paperboard and paperboard coated with PE polymer or PET polymer. The study was an approach to the perforations on the paperboard and how to design its patterns. The study focused on to which degree does the perforation influences the strength of the paperboard materials. The third research question was whether the diameter and the shape of perforations is uniform.The tensile strength testing of these materials was taken under different perforation patterns. Laser micro-perforation tests were taken; the micro-hole diameter and appearance were acquired by microscopes. The WVTR of the micro-perforated paperboard were tested.From comparison of 25 patterns, it is inferred that the better tensile strength could be achieved when the micro-holes placed with more distance and more uniformly. The less perforation done on horizontal direction of the sample, the better tensile properties it gains.The less destructing rows made on the samples, the better tensile strength the sample gets.More even and straight fraction surfaces appeared in MD samples, while CD samples also have slant and more layered fraction surfaces. Tensile strength in MD is close to two times higher than CD samples. The strain at break of one CD samples is about triple of the MD samples. The operation time to strain one CD sample to break is about two times of one MD sample. The changes of tensile strength in MD are clearer than in CD. These results are caused by the fibers orientation.The appearance differences between micro-holes of the three materials are quite obvious. For manual made perforated hole, the surface is not smooth enough, and the diameter in sidel is bigger than in side 2. For laser made perforation, the paperboard got discoloration due to laser, perforation on uncoated board is more flat, outstanding ring circles appeared on PET and PE boards, and a few bubbles could be seen around the ring circle of PET coated board. The uncoated sample absorbs the largest amount of water.Uncoated samples absorbed the largest amount of water than PET coated samples, and PE coated samples absorbed the least. The perforation could increase the WVTR of boards effectively. The design of patterns and the micro-hole observation could give the theoretical reference for manufactures or engineers who wants to apply the laser perforation on composite paperboard. |
