Development of Novel Flattening Method for Bamboo Cane by the High-Pressure Steam Processing

Abstract

To expand the various kinds of utilization of bamboo, development of a novel flattening method for bamboo cane was conducted. 3－5 year-old Phyllostachys bambusoides （outer circumference : 240－ 275 mm） canes were softened with high-pressure steam, and were pressed into a stainless-steel form- ing pipe （inner circumference : 220 mm） using a horizontal pressing apparatus. A linear cut was made along the fibrous direction of the compressed bamboo cane, and the specimen was softened by soaking in hot water （70－80° C）. The bamboo cylinder was partially opened by hand, and subsequently it was flattened by pressing using a stainless steel board newly developed for flattening bamboo. The results indicated that the best steaming condition for circumferential compression of bamboo cane was 140° C for 30 mins, and the ideal compression ratio to flatten the bamboo cane was 14－19%. By circum- ferential compression, the outer circumference of the specimen becomes smaller than the inner circum- ference of untreated bamboo cane. Therefore, it can be considered that the compressed bamboo is able to accommodate the expansion of the inner wall which is required to flatten the circular product. The flattened bamboo board was successfully obtained after a fixation treatment with high-pressure steam at 180° C for 4 mins.