- 期刊
溶解相思樹樹皮製造木材膠合劑之研究
Studies on the Manufacturing of Wood Adhesives with Liquefied Bark of Acacia confusa
摘要
本研究乃探討相思樹樹皮在酚液體中以鹽酸或硫酸為催化劑進行液化反應，並進一步將此液化樹皮全量應用於木材膠合劑製備之可行性。由試驗結果得知，樹皮液化時酚／樹皮之重量比應在3/1以上，以H_2SO_4為催化劑者之液化效果優於以HC1為催化劑者，其液化樹皮中與酚結合之不揮發分含量較高，未反應之樹皮殘渣量則較低。以H_2SO_4為催化劑之液化樹皮所合成之樹脂固形分含量高於以HC1為催化劑者，各合成樹脂之粘度則有隨催化劑使用量增加或液化處理時間延長而降低之趨勢。在未添加填充劑時，各合成樹脂之膠合強度以HCI為液化催化劑者較高，添加樹皮粉為填充劑時，各膠液之膠合強度均可獲得明顯改善，且常態下之膠合力均可達7.7 kgf／cm^2以上，以H_2SO_4為液化催化劑，並反應90分鐘者，其常態之膠合強度可達13.1 kgf／cm^2，耐60°C水之膠合強度亦達8.6 kgf／cm^2，然耐沸水返覆之膠合強度仍偏低。各不同液化條件樹皮所製備膠合劑在DSC熱硬化性分析時，其熱硬化過程中之最高放熱峰溫度在143.8°C至146.6°C之間，放熱峰高度及硬化反應熱則各膠合劑間有很大差異，又各膠合劑隨合成反應時間延長，其最高放熱峰溫度略為提高，但硬化反應熱則明顯下降。液化條件對其液化樹皮與甲醛反應時之起始加成反應之影響大於隨後之縮合反應。各液化樹皮膠合劑之熱硬化反應多趨近於一級反應，且符合Arrhenius之動力學方程式，其硬化反應速率之對數（Ink）與絕對溫度之倒數（1／T）呈直現線相關。
並列摘要
This study nvestigated the liquefaction of Taiwan acacia bark by acid catalysts such as hydrochloric acid (HC1 and sulfuric acid (H_2SO_4) in phenol, and the -feasibility of wood adhesives production from these liquefied barks. At the time of liquefaction the weight of phenol should exceed three times that of bark. The effects of H_2SO_4 catalyst on liquefaction was better than HC1. Higher content of phenol-combined non-volatiles and lower content of unreacted bark residue were found in the hydrochloric acid case. Synthetic resins prepared by liquefied bark using H_2SO_4 as a catalyst had higher solid contents than those with HC1. Resin viscosities decreased with increasing catalyst concentration or the reaction time of liquefaction. Adhesives prepared by liquefied bark using HC1 as a catalyst had better bonding strength than using H_2SO_4 with no filler added. The bonding strength of all kind of adhesives was improved significantly as filler added, the dry bonding strength achieved 7.7 kgf/cm^2. Adhesives prepared from liquefied bark using H_2SO_4 as a catalyst and 90 minutes of liquefaction showed 13.1 kgf/cm^2 of dry bonding strength and 8.6 kgf/cm^2 of wet bonding strength after 60°C water soaking. The bonding strength after repeated soaking in boiling water was still poor. The exothermic peak temperatures of all adhesives at thermosetting were between 143.8°C and 146.6°C, whereas the peak height and exothermic heat at curing varied greatly. The exothermic peak temperature increased with synthetic reaction time for all adhesives. The exothermic heat at curing decreased with reaction time through. The liquefaction condition exerted greater influence on the initial addition reaction than the following condensation reaction for the resin formation. The thermosetting reaction of each adhesive was first order reaction, and showed a linear relationship between the logarithm of velocity and the reverse of absolute temperature (In k vs. 1/T), in correspond with the kinetic equation of Arrhenius.