低成本E_2级人造板用脲醛树脂胶的制备及其应用

Preparation and application of low cost urea-formaldehyde resin adhesive for E_2 grade manufactured board

采用碱-酸-碱工艺,控制酸性阶段的pH值为4.0～4.3,n(F)/n(U)=1.15～1.23,研制出可用于胶合板和中密度板(MDF)生产的脲醛(UF)树脂胶。该胶制备工艺简单、游离甲醛含量低、制胶时间短、再现性好、成本低且贮存期达30 d以上。以NH4Cl为固化剂压制的胶合板,其胶合强度符合Ⅱ类板的国家标准,甲醛释放量<3.0 mg/L;不加固化剂直接压制的MDF,其强度和甲醛释放量达到E2级标准。

The urea-formaldehyde（UF） resin adhesive for plywood and middle density fibreboard（MDF） was synthesized by alkali-acid-alkali traditional process when a pH value in the acid stage was between 4.0 and 4.3, molar ratio of F and U was between 1.15 and 1.23. The adhesive had many characteristic of simple manufacture process, low free formaldehyde, short producing time, good reproducibility, low cost and longer reserve time （〉30 days）. The plywood was manufactured with ammonium chloride as curing agent, and the bonding strength could meet the requirement of relevant country standard for type Ⅱ plywood （0.7 MPa）, the formaldehyde releases was less than 3 mg/L, but the MDF without curing agent was up to the standard of E2 grade.