PEI/APP改性脲醛树脂制备阻燃胶合板及性能

以聚乙烯亚胺(PEI)为改性剂处理聚磷酸铵(APP)制备得到APP@PEI阻燃体系,并将其加入到脲醛树脂(UF)中,制备阻燃胶合板。研究了APP@PEI对UF胶黏剂理化性能的影响,并进一步探讨其对胶合性能及阻燃性能的影响。结果表明:APP、PEI和APP@PEI对UF的黏度、pH和固化时间均有影响。当APP添加量为10%时,UF的黏度由3.843 Pa·s上升至8.270 Pa·s,pH降至5.67,固化时间由91 s降至87 s;当PEI添加量为0.91%时,由于UF体系中支化和交联程度增加,黏度上升至41.433 Pa·s,pH和固化时间分别提升至9.91和116.3 s;而APP@PEI能降低对UF各项性能的影响,添加10%APP@PEI时UF的黏度、pH和固化时间分别为5.966 Pa·s、6.33和94.3 s。添加APP后,胶合板的胶合强度均低于Ⅱ类胶合板强度标准(0.7 MPa);添加PEI后,胶合板的胶合强度能够提升18%以上;APP@PEI添加量为10%时,胶合板的胶合强度达0.85 MPa,高于Ⅱ类胶合板强度标准要求。添加APP、PEI和APP@PEI对胶合板的阻燃性能有不同影响,单独添加PEI无法改善胶合板的阻燃性能,当APP和APP@PEI添加量为10%,15%和20%时,胶合板的极限氧指数(LOI)分别比未添加阻燃剂时提高0.8%,2.0%,2.5%和1.2%,2.2%,3.1%。

Preparation of flame?retardant plywood by PEI/APP modified urea?formaldehyde resin and its properties

Plywood is a material made of gluing wood veneers together and widely used in construction,interior deco?ration,transportation,and other fields.However,plywood is a kind of flammable wood material and has a great risk of fire when it is not treated by flame?retardant,which limits its applications.At present,the flame?retardant treatment of plywood is mainly completed by impregnating veneers or plywood with flame retardant solution.However,this method generally requires a large amount of flame retardant solution and long?time impregnation.Moreover,wood may be deformed after drying and the flame retardant would affect the appearance of the board surface.Using flame retardant adhesive to prepare plywood is a relatively simple method,which can complete the production of flame re?tardant plywood during the preparation process.However,there is a problem that the bonding strength decreases after adding the flame retardant.In this paper,ammonium polyphosphate(APP)was modified by polyethylenimine(PEI)to prepare APP@PEI flame retardant,and APP@PEI was added to urea?formaldehyde resins(UF)to prepare flame retardant plywood.The effects of APP@PEI on the physical and chemical properties of UF adhesive were studied,and its effects on the bonding strength and flame retardant properties of plywood were further discussed.The results showed that APP,PEI and APP@PEI had effects on the viscosity,pH value and curing time of UF.Compared with UF,when the addition of APP was 10%,the viscosity of UF increased from 3.843 Pa·s to 8.270 Pa·s,the pH de?creased from 7.73 to 5.67,and the curing time reduced from 91 s to 87 s.When the addition of PEI was 0.91%,due to the increased degree of branching and crosslinking in the UF system,the viscosity increased to 41.433 Pa·s,and the pH value and curing time increased to 9.91 and 116.3 s.APP@PEI can reduce the impact on the performance of UF.When adding 10%APP@PEI,the viscosity,pH value and curing time were 5.966 Pa·s,6.33 and 94.3 s,re?spectively.After adding APP,the bonding strength of plywood was lower than the strength required by the Standard of Type II plywood(0.7 MPa).After adding PEI,the bonding strength of plywood increased by more than 18%.When the amount of APP@PEI was 10%,the bonding strength of plywood was up to 0.85 MPa,which was higher than the strength required by the Standard of Type II plywood.In addition,the addition of APP,PEI and APP@PEI had dif?ferent effects on the flame retardancy of plywood.Although adding PEI can improve the bonding strength,it cannot improve the flame retardancy of the plywood when adding it alone.When the addition of APP and APP@PEI was 10%,15%,20%,the limiting oxygen index(LOI)of the plywood was higher than that of non?added.The LOI in?creased by 0.8%,2.0%,2.5%and 1.2%,2.2%,3.1%,respectively.The results showed that,compared with adding APP to UF,adding APP@PEI can both improve the bonding strength and flame retardancy of plywood.