防止橡膠木發生棕變之窯乾基準

Kiln Schedule for Preventing Brown-stain in Rubber Wood

翟思湧(Sy-Yung Jai) ； 黃清吟(Chin-Yin Hwang) ； 熊如珍(Ju-Chen Hsiung)

《林業試驗所研究報告季刊》 7卷1期 (1992/03) Pp. 73-91

https://doi.org/10.7075/BTFRI.199203.0073

摘要

為製訂－防止橡膠木在窯乾過程中發生棕變之窯乾基準，特以初期採用低溫低濕(DBT=40℃，WBD=5℃）最高窯溫－為7l℃，另－為82℃；以及初期採用中溫低濕(DBT=54℃，WBD=6℃)最高窯溫亦為82℃之三個窯乾基準，就3cm與5cm厚之橡膠木進行試驗。結果顯示：低溫低濕之窯乾基準，可有效防止橡膠木板材之表層發生棕變，但對心層之輕微棕變，則不具防止效應；中溫低濕之窯乾基準，會使橡膠木板材之表層與心層均發生中庸程度之棕變；唯，中溫低濕之基準，具有節省能源與縮短乾燥時間之功效。

關鍵字

窯乾基準 ； 測色色差計 ； CIE LAB色彩體系 ； 色彩參數 ； 棕變 ； 橡膠木

並列摘要

Brown-stain in rubberwood (Hevea brasiliensis) lumber during kiln drying is a fairly common problem, particularly under high temperature drying. The objective of this study was to develop a kiln schedule for producing the normal whitish yellow colour of rubberwood. Three kiln schedules were used for this study and the drying conditions were:
A: initial low temperature and low humidity (DBT=40℃, WBD=5℃), max. temperature =71℃;
B: initial low temperature and low humidity, max. temperature =82℃;
C: initial medium temperature and low humidity (DBT=54℃, WBD=6℃), max. temperature =82℃.
The sizes of the test board were 3 and 5cm (T)×l2cm (W)×l20cm (L). After kiln drying, the test boards were compared primarily for color parameters and color differences based on CIE LAB specifications. Besides, the drying efficiency was also investigated.
From this study we have concluded:
1. A kiln schedule that provides initial lower temperature and lower humidity (DBT＜40℃, WBD＞5℃) and the max, temperature not over than 82℃ can prevent the occurrence of brown-stain in the shell of rubberwood lumber however, a moderately brown-stain still appears in core.
2. A initial medium temperature and lower humidity (DBT＞54℃, WBD＞5℃) and max. temperature not over than 82℃ kiln schedule is susccpitable to incur moderate brown-stain in the shell and core of rubberwood lumber.
3. The degree of brown-stain is not affected by the thickness of the test boards which dried under same kiln conditions.
4. The initial medium temperature and lower humidity kiln schedule reduces quite a Jot of drying time and energy consumption, as compared with the initial lower temperature and lower humidity ones.
5. We recommand that further tests be conducted to find out the best combination of temperature and humidity for preventing brown-stain both in the shell and core of rubberwood lumber.

並列關鍵字

kiln schedule ； color and color difference meter ； CIE LAB system ； color parameters ； brown-stain ； rubberwood