樹皮萃取物應用於低甲醛尿素膠木質板類之製造

Application of Bark Extractives to the Manufacturing of UF Wood-based Boards with Low Formaldehyde Emission

李文昭(Wen-Jau Lee) ； 劉正字(Cheng-Tzu Liu)

《林產工業》 22卷1期 (2003/03) Pp. 45-51

https://doi.org/10.6561/FPI.2002.22(1).5

摘要

本研究乃探討相思樹樹皮之熱水萃取物及1% NaOH萃取物添加對尿素膠合板游離甲醛釋出量及合板膠合強度之影響。由結果得知，UF膠之性質受合成時甲醛與尿素之莫耳比(F/U)所影響，F/U為1.8及2.0兩種UF膠比較，1.8者有較高之固形分含量及粘度，較低之未反應甲醛含量及較短之膠化時間。UF膠合板製造時，採較低F/U莫耳比之UF膠或提高熱壓溫度均可降低其游離甲醛釋出量。添加樹皮萃取物可明顯降低UF膠合板之游離甲醛釋出量，熱壓溫度130℃時，隨萃取物添加量增加，其游離甲醛釋出量有降低之趨勢。然合板膠合強度則因樹皮萃取物添加而降低，添加熱水萃取物者之常態膠合強度仍可達CNS 1349號“普通合板”中對柳桉合板膠合強度7.0 kgf/cm^2之要求標準以上，添加1% NaOH萃取物者則膠合不良。

關鍵字

尿素－甲醛膠合劑 ； 樹皮萃取物 ； 游離甲醛釋出量

並列摘要

The main purpose of this study was to investigate the effect of addition of bark extractives from Taiwan acacia (Acacia confusa Merr. ) by hot water or 1% NaOH to UF adhesive on the free formaldehyde emission and bonding strength of plywood. The molar ratio of formaldehyde to urea (F/U) at the stage of UF adhesive synthesis would influence the properties of UF adhesive. Comparing the UF adhesive properties with F/U ratio of 1.8 and 2.0, the former had higher solid content and viscosity, lower unreacted formaldehyde content, and shorter gel time. Plywood made with UF adhesive that had lower F/U molar ratio or made with higher hot pressing temperature decreased the free formaldehyde emission. Plywood made with UF adhesive with the addition of bark extractive decreased the free formaldehyde emission significantly. At hot pressing temperature of 130℃, increased the amount of bark extractive addition, free formaldehyde emission would decrease accordingly. Bonding strength of plywood made by UP adhesive with bark extractive addition decreased, but the dry bonding strength of plywood with hot water extractive addition was .over 7.0 kgf/cm^2, which could meet the requirement of CNS 1349 for plywood made with lauan, but the bonding strength of plywood with the addition of 1% NaOH extractive was not good.

並列關鍵字

Urea-formaldehyde adhesive ； Bark extractive ； Free formaldehyde emission