Case Study II – Use of Twist Wrap PackagingPosted by superadmin on Apr 16, 2013 in Case Study | 0 comments
Candy wrappers are required to be non-sticky to avoid sticking to candies/ toffees packed inside them. Candy wrappers package individual candies and hence wrappers should show high degree of machinability which essentially means that they should be static free and should not curl inside the high-speed packaging machines so as to minimize machine down-time. Another very important characteristic of candy wrappers are is that they are twisted on both sides to enclose and secure the candy inside the wrapper. The candy can thus be taken out of the packaging by un-twisting the wrapper. Finally, candy wrapper should be shiny and glossy so as to attract attention.
We received an inquiry from Israel for a wax paper based candy wrapper. Usually, most of the desired characteristics of a candy wrapper are easily fulfilled by a twsit grade PVC or polyester film wrapper, however this particular client preferred the feel of paper over plastic and wanted a non stick, high-gloss, twist grade wax paper wrapper.
From earlier experiences of supplying wax paper to confectionery companies, we knew that twisting ordinary paper results in tear at the neck of the candy because cellulose fibres inside the paper not able to withstand the tension created by the twist. The first and foremost requirement was to find the right paper with appropriate strength and at the same time having high gloss. We zeroed in on a variety of chromo paper, made the first sample and sent it to our client in Israel. The client reverted back within two days that the paper although having high strength but was still not tear-free on twisting. He stressed that tensile strength of cellulose fibre seems fine but it maybe the softness of the paper which is the reason for tear ie the paper was still offering resistance to twisting and hence tearing.
Normal moisture content of paper is 5-7% of its total weight. Paper is hygroscopic in nature and depending on the amount of moisture in the air, or the relative humidity of the surrounding environment, the length and/or width of a paper can change depending on how much water the paper has gained or lost. The moisture content of paper also affects its various mechanical, surface, and electrical properties.
Even while processing paper like hot dip wax coating, the moisture content of paper may change and similarly if the paper is moved from a warm humid climate to a cold dry climate the moisture content of paper will change automatically. We realized that in order to make paper more robust to withstand moisture variations we needed to coat it with a glycerol to soften and reduce the shrinkage/elongation of paper due to moisture variations. Glycerols are very highly hygroscopic and they absorb water from the air. The glycerol coated paper hence is able to maintain high moisture levels thereby making it softer to touch and more pliable to twisting forces.
We prepared another sample roll and rushed it to our client and with hours we got a positive response. Although we got the order and everything seemed to be working now, there was more research and development waiting to be done. What happened was that the sample we had sent to our client was an unprinted sample. But when we started processing the order, after printing the paper and coating it with glycerol, the printed side of the paper got stuck with the glycerol coated side. Infact the bonding was so strong that the paper would tear but not leave the other layer. We were on the verge of wasting the entire lot and were already running short of time to dispatch the wrapper.
We again got back thinking and trying out various things. Finally, we realized that it was lack of humidity in cold December month because of which glycerol was losing moisture and getting stuck to the printed side of the paper. We used heaters and humidifiers to change ambient conditions and slowly unwound the paper rolls separating the stuck layers carefully and without damaging.