三聚氰胺-尿素-甲醛共缩聚树脂胶粘剂的研制

通过合成三聚氰胺-尿素-甲醛树脂(MUF)胶粘剂,探讨了三聚氰胺用量对该MUF胶粘剂耐水性和其它性能的影响。结果表明:随着三聚氰胺用量的增加,MUF胶粘剂的耐水性能提高、固含量增大、固化时间和储存期延长,并且胶合板剪切强度增大,但MUF胶粘剂中游离醛含量降低;当w(三聚氰胺)40%时,MUF胶粘剂性能提高并不明显,为了降低成本,选择w(三聚氰胺)=30%～40%时较适宜;三聚氰胺用量不同是影响MUF结构和基团含量的主要因素。     

三聚氰胺含量对MUF性能的影响

MUF(三聚氰胺-尿素-甲醛共缩聚树脂)兼具UF(脲醛树脂)和MF(三聚氰胺甲醛树脂)的优点,通过调节m(三聚氰胺)/m(尿素)配比,可得到性价比较高的MUF;然后采用MUF胶粘剂制备刨花板,并考察了三聚氰胺含量对刨花板的内结合强度、耐水性和耐沸水性等影响。结果表明:三聚氰胺的引入,虽能有效提高MUF的性能,但并非加量越多越好;当w(三聚氰胺)=11.0%~14.0%时,MUF的性价比相对最高,相应刨花板的内结合强度、耐水性和耐沸水性俱佳。     

粉状脲醛树脂的制备及性能优化

采用M(三聚氰胺)对UF(脲醛树脂)改性,并经高温干燥过程制备粉状MUF(三聚氰胺改性脲醛)树脂,并对M掺量、M两次添加比例、树脂固含量与固化剂影响MUF树脂性能规律进行探究。结果表明:随三聚氰胺添加量增加,MUF粉状树脂甲醛释放量逐渐降低,胶接强度先增后降,并在w(M)=5%(相对于UF总质量而言)时达到最佳;当M两次添加比例m(M_1)∶m(M_2)=1∶4,树脂胶接强度最大,粉状树脂颗粒均匀,分散性较好;液体MUF树脂固含量为30%时,干燥后制备的粉状树脂胶接强度最大、甲醛释放量最低;m(固体固化剂)∶m(粉状树脂)=15∶100比例混合时,MUF树脂胶粘剂综合性能最佳。     

三聚氰胺-尿素-甲醛共缩聚树脂的热性能分析

以三聚氰胺、尿素和甲醛为主要原料,制备了MUF(三聚氰胺-尿素-甲醛共缩聚树脂)。三聚氰胺的引入可赋予MUF相对较优的性能;通过考察不同条件下MUF的热分解过程,可综合评价其耐热性能。研究结果表明:在N2气氛中,无固化剂时液态MUF的600℃残炭率高于固态MUF;当m(MUF)∶m(氯化铵)=100∶1时,液态MUF和固态MUF的热分解过程不尽相同,储存时间对液态MUF的耐热性影响不大,但其最终残炭率随储存时间延长而略有增加。     

不同合成方法对MUF共缩聚树脂性能的影响

以三聚氰胺、尿素、甲醛为主要原料,合成了三聚氰胺-尿素-甲醛(MUF)共缩聚树脂。考查了不同合成方法对MUF共缩聚树脂性能的影响。结果表明,不同合成工艺对树脂的甲醛含量以及稳定性有重要影响。DSC分析发现,在相同固化条件下,以工艺2合成的MUF树脂固化速度更快。用MUF制备的胶合木的性能,均可满足日本JAS中的规定。     

三聚氰胺-尿素-甲醛共缩聚树脂的性能研究

合成了三聚氰胺-尿素-甲醛(MUF)共缩聚树脂,考察了不同施胶量、固化剂用量及木材种类对胶合木性能的影响。结果表明,MUF共缩聚树脂用量为300g/m2,双面施胶,固化剂用量在1~2%时,生产的胶合木性能最优。     

基于膨润土的脲醛树脂填料的开发与性能研究

比较了面粉、膨润土及其用量对脲醛(UF)树脂胶粘剂的pH值、固含量、固化时间和胶合强度的影响,探讨了膨润土用作胶粘剂填料的可行性。研究结果表明:随着膨润土用量的增加,UF树脂胶粘剂的pH值、固化时间和固含量呈递增趋势,游离甲醛含量明显下降;随着面粉用量的增加,UF树脂胶粘剂的固含量和固化时间呈递增趋势(但增幅比膨润土体系小),pH值有所降低;用添加膨润土的UF树脂胶粘剂生产的胶合板,当w(膨润土)≤20%、施胶量为280～300 g/m2时,胶合板的湿态胶合强度(1.69 MPa)比面粉体系(1.53 MPa)和纯UF树脂胶粘剂体系(1.09 MPa)的高,其湿态胶合强度能达到GB 9 846-1988的标准,而干态胶合强度则远高于GB 9 846-1988标准。     

MUF MF共缩合改性树脂胶黏剂的研究

同时采用共聚和共混的方法,合成了一种脲醛-三聚氰胺甲醛复合树脂胶黏剂。研究了合成工艺、三聚氰胺用量、MF与MUF共混比例对胶黏剂性能的影响。结果表明,反应后期加入5%三聚氰胺改性MUF树脂,MUF和MF树脂按M/U为40%共混时,共混树脂游离甲醛含量较低,耐水性能优良,综合性能较好。     

单宁改性集成材用MUF树脂胶粘剂

以对甲苯磺酸处理过的单宁为改性剂,研究了不同添加阶段、不同添加量对集成材用三聚氰胺-尿素-甲醛(MUF)共缩聚树脂性能的影响,并借助红外光谱(FT-IR)和差式扫描量热(DSC)进行表征。结果表明,在"碱-酸-碱"工艺过程的一碱阶段添加12%处理单宁对MUF树脂进行改性的效果最佳,所制备树脂黏度低、游离甲醛含量不高,干状和湿状剪切强度均满足国家结构集成材用胶标准。FT-IR和DSC分析结果表明,酸性阶段加入单宁可能会阻碍缩聚反应进行,一碱阶段加入单宁合成的MUF具有较低的固化温度。     

MF合成工艺对MUF储存稳定性影响研究

从三聚氰胺甲醛树脂(MF)合成阶段的n(F)∶n(M)配比、缩聚时间、改性剂和稀释剂含量方面,探讨了MF合成工艺对MUF(三聚氰胺-尿素-甲醛树脂)储存稳定性的影响。研究结果表明:当MF制备过程中n(F)∶n(M)=1.8∶1、MF缩聚时间为120 min、pH值为9.5、PVA(聚乙烯醇)水溶液为稀释剂和使用双组分改性剂时,MUF的储存稳定性相对最好,并且相应胶合板的胶合强度相对最大。     

Soybean meal-based adhesive enhanced by MUF resin

Soybean meal flour, polyethylene glycol (PEG), sodium hydroxide (NaOH), and a melamine-urea-formaldehyde (MUF) resin were used to formulate soybean meal/MUF resin adhesive. Effects of the adhesive components on the water resistance and formaldehyde emission were measured on three-ply plywood. The viscosity and solid content of the different adhesive formulations were measured. The functional groups of the cured adhesives were evaluated. The results showed that the wet shear strength of plywood bonded by soybean meal/NaOH adhesive increased by 33% to 0.61 MPa after adding NaOH into the adhesive formulation. Addition of PEG reduced the viscosity of the soybean meal/NaOH/PEG adhesive by 91% to 34,489 cP. By using the MUF resin, the solid content of the soybean meal/MUF resin adhesive was improved to 39.2%, the viscosity of the adhesive was further reduced by 37% to 21,727 cP, and the wet shear strength of plywood bonded by the adhesive was increased to 0.95 MPa, which met the interior plywood requirements (≥0.7 MPa). The formaldehyde emission of plywood bonded by the soybean meal/MUF resin adhesive was obtained at 0.28 mg/L, which met the strictest requirement of the China National Standard (≤0.5 mg/L). FTIR showed using the MUF resin formed more  CH₂ group in the cured adhesive. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effects of diatomite inorganic fillers on the properties of a melamine–urea–formaldehyde resin

In this study, a low‐cost diatomite was used to partly substitute wheat flour as one type of melamine–urea–formaldehyde (MUF) resin filler. Five‐ply plywood was fabricated, and its performance was measured. The crystallinity, fracture surface, and functional groups were tested to determine the effects of diatomite on the performance of the MUF resin. The results show that diatomite was well distributed in the MUF resin system and formed an embedding structure; this improved the wet shear strength of the resulting plywood by 33% to 1.36 MPa. Diatomite captured the free formaldehyde in the resin and the microporous structure formed in the resin accelerate formaldehyde release of the plywood. Consequently, the formaldehyde emission of the plywood was reduced. The diatomite partly replaced wheat flour as an MUF resin filler and could be applied in the plywood industry. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44095.     

三聚氰胺添加方式对MUF胶粘剂性能的影响

以三聚氰胺作为脲醛树脂(UF)的共聚改性剂制备MUF(三聚氰胺甲醛树脂)胶粘剂。探讨了三聚氰胺的添加方式对MUF胶粘剂性能的影响,同时对其固化特性、分子结构和耐热性等进行了分析。结果表明:三聚氰胺2次投料法可有效降低MUF胶粘剂的甲醛释放量,但其胶接强度也随之下降;同时,该MUF固化体系的外推固化温度、表观活化能和反应级数均有所增加,耐热性降低;另外,2次投料体系使MUF的相对分子质量降低、相对分子质量分布变宽。     

Determination of formaldehyde and TVOC emission behavior from interior use plywood using various post heat treatment processes

To reduce the formaldehyde/TVOC emissions from plywood with melamine–urea–formaldehyde (MUF) resin, four heat treatment procedures were designed and applied. Five‐ply plywood was fabricated, and its formaldehyde/TVOC emissions and wet shear strength were tested. Results showed that a simple low/no pressure post heat treatment procedure was effective and practical to decrease the formaldehyde/TVOC emissions from plywood. This was attributed to completely cured of MUF resin, the breakage of unstable chemical bonds, the acceleration of free formaldehyde releasing, and the exposed surface of the plywood. Meanwhile, this process also balanced the interior force of the resultant plywood and improved its wet shear strength. Under a 12 h oven heat treatment procedure after hot press, the formaldehyde and TVOC emissions from plywood decreased to 0.020 and 0.036 ppm, respectively, while the surface and core layer wet shear strength of plywood was improved to 1.24 and 1.08 MPa. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44909.     

Acetal‐induced strength increases and lower resin content of MUF and other polycondensation adhesives

Acetals such as methylal and ethylal are shown to be particularly effective additives in improving the strength of wood boards bonded with melamine‐ urea‐formaldehyde (MUF) resins, although they show some appreciable but lesser effect on other resins too, particularly phenol‐ formaldehyde resins. They equally allow a considerable decrease in resin loading, and thus, in melamine content, on the bonded wood panel and at parity of performance. Their development as additives is then primarily, but not only, targeted at the MUF adhesive resins. One‐third decreases in MUF adhesives loading at parity of performance or equally internal bond (IB) strength increases approximately up to 50% by addition of methylal are shown to be possible by laboratory particleboard as well as by thermomechanical analysis (TMA). The reasons for methylal and ethylal behavior were studied by a variety of techniques, including liquid‐ and solid‐ phase ¹³C‐NMR and could be mostly ascribed to the increased effectiveness and participation of the melamine to resin crosslinking due to its now preferentially homogeneous rather than heterogeneous reactions, consequences of the increased solubility in water afforded by the acetal cosolvents. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2561–2571, 2002     

竹碎料板用低毒脲醛树脂的合成工艺研究

在脲醛树脂(UF)的制备过程中,采用三聚氰胺对UF进行改性,制得低毒UF。结果表明:该低毒UF的固含量为49.88%,游离甲醛释放量仅为0.2026%;采用这种低毒UF胶粘剂压制的竹碎料板,其静曲强度为22.6MPa,弹性模量为2056MPa,内结合强度为0.58MPa,2h吸水厚度膨胀率为2.57%;该低毒UF是一种综合性能良好的木材用胶粘剂,其应用前景非常广阔。     

A Soy Flour-Based Adhesive Reinforced by Low Addition of MUF Resin

The desire to prepare a lower-cost soy-based adhesive has led to an interest in using the abundant and inexpensive soy flour (SF) as a substitute for expensive soy protein isolates (SPI) in wood adhesives. However, the weakness of this adhesive is poor water-resistance and bonding strength due to a low protein content, which limits its application in the wood industry. The objective of this research was to provide a simple and useful approach for improving the adhesion performance of SF-based adhesive by introducing a small addition of melamine-urea-formaldehyde (MUF) resin into the cured system. The optimum addition level of MUF resin, as well as the adhesion performance and conformation change of SF-based adhesive, were investigated. The analytical results indicated that the co-condensed methylene bridges were formed through the reaction of methylol groups of MUF resin with soy units during the hot-press process. The addition of MUF resin, not only significantly decrease the viscosity of SF-based adhesive but also increase its water-resistance and wet shear strength value. The SF-based adhesive containing 20% MUF resin, is a relatively low-cost adhesive, has a reasonable viscosity, and moreover can pass the Chinese Industrial Standard requirement (0.7 MPa) for interior plywood panels.