液化杉木樹皮製造酚－甲醛木材膠合劑

Manufacture of Phenol-formaldehyde Wood Adhesives Using Liquefied Bark of ＂Cunninghamia lanceolata＂

李文昭(Wen-Jau Lee) ； 劉正宇(Cheng-Tzu Liu)

《林產工業》 20卷3期 (2001/09) Pp. 217-226

https://doi.org/10.6561/FPI.2000.20(3).5

摘要

本研究將杉木樹皮在酚液體中以鹽酸或硫酸為催化劑進行液化反應，探討不同條件之液化樹皮所製備酚－甲醛膠合劑之性質。樹皮液化時酚／樹皮之重量比3/1，催化劑添加量為酌使用重量之5~12.5%，液化反應時間為60~150 min，酚－甲醛膠合劑合成時置酚／甲醛之莫耳比為1.0/1.8。由試驗結果得知，杉木樹皮在酚液體中行液化反應時，催化劑種類為影響液化效果之主要因素，以H2_SO_4為催化劑者之液化效果優於以HCI為催化劑者，其液化樹皮中之殘渣量較低，不揮發分及結合酚含量則較高。不同液化條件杉木樹皮所製備膠合劑之不揮發分、pH值及鹼含量無明顯差異，然以H_2SO_4為液化催化劑者其膠合劑之粘度較高，膠化時間較短。以HCI為液化催化劑之液化樹皮在膠合劑合成時所進行之加成反應較快，且其所製備膠合劑在熱硬化過程中所發生之架橋反應程度較以H_2SO_4為催化劑者高。以H_2SO_4為液化催化劑之液化樹皮所合成膠合劑在DSC熱分析時有較低之最高放熱峰溫度及onset溫度，較少之硬化反應熱，其熱硬化之熱流曲線受液化條件所影響，在H_2SO_4添加量10%之液化條件下，其膠合劑在熱硬化過程中出現兩個放熱峰。以HCI為液化催化劑者，不同液化條件樹皮所合成膠合劑之熱硬化曲線並無明顯差異。以HCI為液化催化劑之液化樹皮所合成膠合劑之膠合強度優於以H_2SO_4為液化催化劑者，其常態、溫水浸水及反覆煮沸浸水之膠合強度均可達CNS中國國家標準中所規範之強度要求以上，以H_2SO_4為液化催化劑者則其常態及溫水浸水膠合強度可達要求標準，反覆煮沸浸水膠合強度則偏低。

關鍵字

酚－甲醛膠合劑 ； 液化樹皮 ； 熱硬化性

並列摘要

Bark of China fir (Cunninghamia lanceolata) was liquefied in phenol using hydrochloric acid (HCI) or sulfuric acid (H_2SO_4) as a catalyst. The properties of phenol-formaldehyde wood adhesives (PF) that prepared from liquefied China fir bark were investigated. As bark liquefaction, the weight ratio of phenol to bark was 3/1, the concentration of catalyst was 5 % to 12.5 % based on the weight of phenol and the liquefaction reaction time was 60 min to 150 min. As phenol-formaldehyde wood adhesives preparation, the molar ratio of phenol to formaldehyde was 1.0/1.8. The results were summarized as follows. Kinds of catalyst were the most important factor that influenced the effects of liquefaction of bark in the presence of phenol. When H_2SO_4 and HCI were used as a liquefaction catalyst, the former had lower content of unreacted bark residue and higher content of non-volatile matter and combined phenol than the latter. So, H_2SO_4 had better liquefaction effect than HCI. The non-volatile matter, pH value and alkali content of PF wood adhesives with various liquefied China fir bark had no significant difference. But the PF wood adhesives prepared from liquefied bark that using H2S04 as a catalyst had higher viscosity and shorter gel time than adhesives prepared from liquefied bark that using HCI as a catalyst. Adhesives prepared from liquefied bark that using HCI as a catalyst had faster addition reaction at the stage of adhesive synthesis, and higher degree of cross-linking at the stage of adhesive thermosetting than adhesives prepared from liquefied bark that using H_2SO_4 as a catalyst. At DSC thermo-analysis, adhesives prepared from liquefied bark that using H_2SO_4 as a catalyst had lower exothermic peak temperature and onset temperature, and had smaller quantity of exothermic heat than adhesives prepared from liquefied bark that using HCI as a catalyst. The trend of thermogram of PF wood adhesive was influenced by the conditions of bark liquefaction that H_2SO_4 was used as a catalyst, as 10 % of H_2SO_4 was used, two exothermic peaks were found at the process of adhesive thermosetting. But there was no difference when HCI was used as a catalyst. Adhesives prepared from liquefied bark that using HCI as a catalyst had bonding strength better than adhesive prepared from liquefied bark that using H_2SO_4 as a catalyst. The former had dry bonding strength and wet bonding strength, which had been soaked with 60℃ and 100℃ water, over the requisite of CNS standard, the latter had dry bonding strength and wet bonding strength which had been soaked with 60℃ water over the requisite of CNS standard, but it was poor after 100℃ water soaked.

並列關鍵字

Phenol-formaldehyde adhesive ； Liquefied bark ； Thermosetting