Ryoichi Seki, Asahi Breweries, Ltd., Containers and Packaging Laboratory, Moriya-shi,Ibaraki,
Packaging (Bottles, Draft, and Cans)
In recent years in the Japanese market, demand for small capacity cans (135 mL) has been growing as the result of the decrease of consumption due to aging and the increase of demand as a small souvenir by foreign travelers. In this small capacity can, a 200-diameter lid (diameter of 52 mm) of the stay-on-tab opening type has been adopted, but compared with the domestic standard 204-diameter can lid, there has been a problem in that it is not easy to open. The reason for this was that since the area of a 200-diameter can lid is small and the technical hurdle in designing it was high because of positive internal pressure, improvement was delayed. Therefore, we followed the idea of the original Kansei (sensitivity) engineering that had improved the ease of opening the 206-diameter can (diameter of 60 mm) to improve the ease of opening the small capacity 200-diameter lid. So, we introduce here the summary of this improvement. "Kansei engineering" is a method to clarify the correlation between sensitivity for goods held by humans and the physical properties of products to engineer the design of a product. In this development, we defined and classified the sensory images held by consumers as "easy to open" into evaluation terms of seven items (ease of lifting tabs, load when opening the lid, etc.). Furthermore, in order to clarify the contribution of these evaluation terms and the sensory characteristics of consumers, we conducted organoleptic surveys on a wide variety of can lids and extracted an organoleptic characteristic attributable to easiness of opening. From these results, we derived that the beginning of opening the tab is particularly important and the goodness of hooking of the tab directly leads to the evaluation of "ease of opening." Next, we listed 15 items on the physical properties of the can lid relating to the "ease of opening" (lifting amount of tab, rigidity of tab, opening force, etc.) and extracted the physical properties deeply relating to the organoleptic characteristics described above. From these results, we found that the physical property strongly correlating with the sensory image, especially "ease of opening," is "lifting amount of tab" (clearance between tab and shell of finger hooking part). Based on the above evaluation model, we executed final prototyping of the can lid by combining elements for improving ease of opening of each component part and confirmed the effect. As a result of conducting the organoleptic examination on 50 subjects by the 5 grade SD (Sematic Differential) method, we obtained an average score of 3.5 (easy to open), superior to the dominant (P<0.01) average score of 2.5 (difficult to open) for conventional can lids. Even on a 200-diameter can lid with a small lid area, we could greatly improve the ease of opening as targeted by adopting the Kansei engineering approach.
Ryoichi Seki currently works in the R&D Laboratories for Packaging of Asahi Breweries, Ltd., in Japan. He is a packaging engineer and his job is to design and develop packaging for beer such as can containers.