Keisuke Ando

Saccharification of cellulose by dry pyrolysis

Pyrolysis of cellulose was studied for the purpose of practical production of 1,6-anhydro-β-D-glucopyranoside (levoglucosan, LG). To minimize secondary degradation of levoglucosan, two methods were examined: (1) conductive heating by glass bottle, and (2) radiation heating from the surface by CO2 laser beam, both under vacuum and in a nitrogen atmosphere. Glass-bottle pyrolysis under vacuum gave levoglucosan yield of 50%–55% in the optimum temperature range of 350°–410°C, where placing the cold trap in the vicinity of heated area was effective in improving the yield. In contrast, glass-bottle pyrolysis under nitrogen gave low yields of 17%–20%, probably due to slower diffusion of pyrolysis product from hot region. The CO2 laser pyrolysis under vacuum gave the product as aerosol (white smoke), causing difficulty in recovery of the product, and the maximum yield was 5%–17%. In this case the treatment under nitrogen flow was effective for recovery of aerosol, and the maximum yield reached approximately 25%.

Passive impregnation of liquid in impermeable lumber incised by laser

Square lumber specimens of laser-incised Douglas fir (Pseudotsuga menziesii Franco) were treated with steam before dipping. Two types of steam (saturated steam and superheated steam), three steam-injection times (5, 10, and 20 min), four different time intervals (moving time) between steam treatment and dipping (immediate, 3, 10, and 30 min), and four different dipping times (0.5, 1, 3, and 12 h) were used in the study. The maximum absorption was 480 kg/m3 when saturated steam was injected for 20 min and the specimen was immediately dipped into liquid for 12 h. Samples treated with this condition not only absorbed the maximum amount of liquid but also penetrated over 83.4% and 87.3% of the total area along and across the grain, respectively. The optimum conditions were then applied to laser-incised sugi (Cryptomeria japonica D. Don) and Japanese larch (Larix leptolepis Gordon) where the absorption of liquid was 415 and 187 kg/m3, respectively. It was shown that initial moisture content below the fiber saturation point was good for passive impregnation. The absorption of liquid and its distribution in wood indicates that it can be a good preservative treatment method for impermeable woods.

Preservative Leaching from Copper Azole–Treated Lumber: A Comparison between the Full-Cell Method and the Passive-Impregnation Method

This study investigated the leaching of copper azole (CA-B) preservative, according to JIS K 1571 standard, from sundri (Heritiera fomes Buch.-Ham.) lumber treated by full-cell and passive-impregnation methods. Although the preservative retention was similar for both methods, penetration was higher with the passive-impregnation method (66%) than with the full-cell method (43%). Further, it was found that the leaching of preservative was significantly higher in wood treated by the full-cell method (1.18%) than by the passive-impregnation method (0.92%).

Impregnation of laser incised wood of Douglas fir and Japanese cedar by dipping (passive impregnation) in solutions of copper azole (CuAz-B) and a fire retardant (PPC)

Abstract The performance of the passive impregnation method of CO2-laser incised lumber has been investigated concerning wood preservation against different wood-destroying agents. Copper azole type B (CuAz-B) preservative and polyphosphatic carbamate (PPC) fire retardant were impregnated into Douglas fir and Japanese cedar lumber under both green and kiln-dried conditions. Final drying of the lumber was performed by steam injection or kiln drying. The temperature and pressure change in the lumber, as well as the total chemical retention, penetration, decay resistance, fire retardancy and total treatment time were calculated according to different standards. The preservative retention was higher in the Japanese cedar for both green and kiln-dried conditions (5.32 and 5.58 kg m-3, respectively) compared to Douglas fir (5.01 and 4.81 kg m-3). Fire retardant retentions were more than 100 kg m-3 in all cases. The penetration was approximately 100% throughout the lumber. There were no significant differences in the decay resistance test between the different categories of lumber. Moreover, it was possible to treat the green lumber in less than 48 h starting from the green conditon to the final drying. Hence, the presented passive impregnation technique could be useful for industrial application.

Effect of steam injection re-drying of Japanese cedar on preservative leaching after passive impregnation

Abstract This study investigated the effects of steam injection re-drying on the leaching of copper azole type B (CAz-B) preservative from green and kiln dried Japanese cedar (Cryptomeria japonica (L.f.) D.Don) lumber treated by the passive impregnation method. The leaching and fungal treatments were performed according to the JIS Z 2101-1994 standard. Sixteen hours of steam injection re-drying reduced the moisture content from 152 to 82% and 195 to 55% for initially green and dry lumber, respectively. Preservative retention was higher in the dry lumber (5.21 kg/m3) compared with the green (4.66 kg/m3), however, leaching percent was similar for both types. Preservative leaching and mass loss due to fungal attack were significantly lower in the lumber re-dried by steam injection compared with air dried. Thus, steam injection re-drying after passive impregnation treatment could be a step toward fixing CAz-B preservative in Japanese cedar lumber.

Drill and laser incising of lamina for fire-resistive glulam

Abstract Conventional glued-laminated timber (glulam) was not permitted to use to a wooden building in the fire preventive district since the amendments of the Building Standards. We already developed a one-hour fire-proof glulam made of Japanese cedar. We also succeeded to give one-hour fire performance to cross laminated timber by the same concept. The both structures are composed of three parts which are load-bearing part, fire-die-out part and surface part. The fire-die-out part is made of lamina incised by CO2 laser and impregnated the fire retardant evenly. As the handling of CO2 laser is not so easy for glulam manufacturer, we felt a growing need for drill incising technology. Therefore, we made pinholes of some diameters up to 2.5 mm to lamina of Japanese cedar, by a drill and investigated differences of hole position on two sides of the lamina. The maximum off-center for length and width directions was 1.8 and 3.3 mm, respectively. These off-centers are 2.3% and 41% of distances between neighboring hole on incising patterns. As the results of impregnating performance and fire-resistive performance of lamina incised by drill, significant differences were not recognized between drill incising and laser incising.

CO2 Laser–Incised Teak and Mahogany Lumber Dried by Microwave and Steam Injection

Abstract The aim of this study was to investigate the application of microwave and steam injection drying on CO2 laser–incised teak (Tectona grandis) and mahogany (Swietenia mahagoni) lumber. The s...