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苯酚-尿素-甲醛三元共缩聚树脂合成工艺的研究 总被引:1,自引:0,他引:1
针对脲醛树脂在制板过程以及人造板材在使用过程中不断释放甲醛。危害人体健康的环保问题,以及耐水、耐老化性能差的缺点。以苯酚、尿素和甲醛为原料,采用高温(90℃)缩聚反应合成苯酚-尿素-甲醛共缩聚树脂(PUF胶黏剂),缩短了反应时间,提高了耐水、耐老化性能,且游离甲醛含量〈O.3%,游离苯酚含量〈0.5%。对树脂的结构和性能进行全面的分析,得出当甲醛、尿素、苯酚摩尔比为10:8:1时树脂性能最佳,压制的胶合板力学性能好,板材甲醛释放量达到GB18580—2001中E2级水平。 相似文献
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苯酚/尿素/甲醛(PUF)共缩聚树脂是一种新型的木材用胶粘剂,其固化特性和耐热特性与酚醛树脂(PF)十分相似,但生产成本明显降低。对PUF共缩聚树脂的合成方法、反应机理、固化特性和影响因素等研究进展进行了综述。 相似文献
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为从根本上消除木材胶合制品的甲醛释放对环境和人体健康的危害及改善尿素-乙二醛(UG)树脂的性能,选择无毒、低挥发的乙二醛代替甲醛,与尿素、苯酚反应制备苯酚-尿素-乙二醛(PUG)共缩聚树脂木材胶黏剂。研究了在反应的不同阶段加入苯酚以及苯酚的加入量对树脂性能的影响,并通过傅里叶变换红外光谱法(FTIR)对树脂的结构进行了表征。结果表明:在所研究的合成条件下,PUG树脂的pH和状态受苯酚加入量和加入时间的影响不大,苯酚的加入量为尿素总量的10%为宜;树脂中主要含有氮氢(N—H)、氧氢(O—H)、羰基(C=O)、饱和碳氢(C—H)、醚键(C—O—C)及碳氮(C—N)键等主要官能团。 相似文献
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以花生壳苯酚液化产物为原料,制备花生壳苯酚液化产物-尿素-甲醛(PLPUF)树脂胶黏剂。采用正交试验探讨了制备PLPUF树脂胶黏剂的最优配比,以提高其综合性能,结果表明:第一批尿素(U1)/第二批尿素(U2)物质的量比、液化产物(PL)/尿素(U总)物质的量比以及液化产物和尿素总用量(PL+U总)与甲醛(F)物质的量比为3:1、1:1.5和1:1是PLPUF树脂胶黏剂制备的最佳配比;此配比下胶合强度达到了0.83 MPa,含固体量为47.11%,游离甲醛的量为0.05%,以酚醛树脂胶黏剂为标准,PLPUF树脂胶黏剂能满足木材工业树脂的使用要求。PLPUF树脂在贮存过程中黏度逐渐上升,贮存5~15 d胶合强度为0.87~1.15 MPa,22 d后胶合强度降低至0.74 MPa,仍可满足使用条件。PLPUF树脂的FT-IR图中出现酰胺C=O和C—N等伸缩振动峰,表明尿素参与反应、改性树脂,而加入固化剂前后树脂的FT-IR吸收峰相同,结合DSC曲线表明固化剂的加入不改变树脂结构,但可以改善PLPUF树脂的固化过程,降低固化温度和固化反应热。 相似文献
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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。 相似文献
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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。 相似文献
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以甲醛( F)、尿素( U)、三聚氰胺( M)为原料,采用弱碱-弱酸-弱碱工艺合成了三聚氰胺-尿素-甲醛( MUF)共聚树脂胶,配方中F与U物质的量之比为(1.2-1.5)∶1,F与(U+M)物质的量比为(1.1-1.2)∶1。在不同的反应阶段取样,采用IR和13C NMR对过程中所取样品进行了分析。结果表明,反应开始的碱性阶段主要生成二羟甲基三聚氰胺,在弱酸性阶段缩聚反应时分子间以醚键和亚甲基键联接为主。用反应最终产物压制的杨木胶合板,胶合强度1.07 MPa,甲醛释放量0.38 mg/L,浸渍剥离试验无剥离,达到E0级,胶合强度达到Ⅱ类板的要求(0.7 MPa)。 相似文献
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Phenol-urea-formaldehyde (PUF) resins of high urea content were prepared at different hydroxyl/phenol (OH/P) mole ratios and formaldehyde/(phenol + urea) [F/(P + U)] mole ratios. The effect of synthesis parameters including OH/P and F/(P + U) mole ratios on the structure, composition, and curing characteristics of PUF resins were investigated by using both liquid 13C nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). The NMR analysis indicated that an increase in the OH/P mole ratio and/or F/(P + U) mole ratio decreased the amount of unreacted urea and monosubstituted urea, and promoted the formation of polysubstituted urea. The DSC results showed that the higher OH/P mole ratio and/or F/(P + U) mole ratio of PUF resins resulted in a lower curing temperature. The F/(P + U) mole ratio of PUF resins seemed to have a more significant accelerating effect on the curing reaction than the OH/P mole ratio. 相似文献
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制备了不同尿素用量的系列尿素改性酚醛(PUF)树脂体系(当尿素用量为苯酚质量的0、25%、43%、66%时分别记为PF、PUF-1、PUF-2、PUF-3),并将其用于制备胶合板,研究树脂在胶合板加工过程中的变化。结果表明:PUF-3树脂与桉木和杨木的接触角为79.6°和81.1°,小于PF树脂的,PUF对桉木相容性比杨木优良,PF树脂则相反;对4种树脂进行DSC分析显示,PF、PUF-1、PUF-2、PUF-3固化速率最大温度分别为146.8、171.4、171.8和171.8℃;PUF-3和面粉共混体系的流变行为显示该共混体系110℃开始发生固化反应,(130±5)℃为较合适的热压温度;对热压前后PF和PUF-3进行热重分析,结果发现PUF的耐高温性能优于PF,热压后形成的结构耐热性也更好;4种树脂压制的胶合板性能达到E0级,甲醛释放量均小于0.5mg/L,胶合强度分别为1.42、1.11、0.98和0.92MPa。 相似文献
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Polymeric 4-4 diphenyl methane diisocyanate (pMDI) was blocked with an aqueous sodium bisulfite solution to obtain water-dispersible blocked pMDI (B-pMDI) resin with different HSO3/–NCO mole ratios for the modification of urea-formaldehyde (UF) resin. Fourier transform infrared (FTIR) spectra of the B-pMDI resin clearly showed that all isocyanate groups of the pMDI resin were successfully blocked by sodium bisulfite. As the HSO3/–NCO mole ratio increased, the de-blocking temperature of the B-pMDI resin also increased. Two addition levels (1% and 3%) of the B-pMDI resin with different HSO3/–NCO mole ratios were mixed with UF resins and used as an adhesive for plywood. The gel time of the UF/B-pMDI resins decreased to a minimum at a mole ratio of 0.9 and then increased with the HSO3/–NCO mole ratio, and was consistent with the peak temperature (Tp). However, as the HSO3/–NCO mole ratio increased, the viscosity of the modified UF resins by 1% B-pMDI resin addition slightly increased, whereas those of modified resins with 3% B-pMDI resin addition rapidly increased. The adhesion strengths of plywood bonded with the hybrid resins were greater for 1% B-pMDI resin addition than for 3% B-pMDI resin addition. Formaldehyde emission of plywood bonded with the UF/B-pMDI resins significantly decreased up to 34% by the addition of B-pMDI resin at a mole ratio of 1.8. These results suggest that the modification of UF resins by mixing with water-dispersible B-pMDI resin can be a method for improving the water resistance and formaldehyde emission of UF resins for wood-based composites. 相似文献
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This study evaluated a new method of producing phenol–urea–formaldehyde (PUF) adhesives formulated differently under actual “in-situ” resin synthesis conditions. This was carried out by co-polymerizing urea formaldehyde (UF) resin with phenol–formaldehyde resin in the core layer of low molecular weight (LMW) phenol–formaldehyde (PF) resin treated Elaeis palm trunk veneers during the gluing process of Elaeis palm plywood. Matrix assisted laser desorption Ionization time of flight (MALDI-TOF) mass spectrometry (MS) illustrated and confirmed a series number of the phenol–urea co-condensates repeating unit in the prepared PUF resins which corroborated well with its mechanical properties (modulus of elasticity and modulus of rupture), bonding quality (dry test and weather boil proof or WBP test) and physical properties. A series of PF, UF and PUF resins oligomers forming repeating units up to 1833 Da were identified. Besides that, the solid state 13Carbon nuclear magnetic resonance (NMR) interpretation identified that the signal at 44–45 ppm and 54–55 ppm corresponding to methylene bridges were co-condensated in between phenol and urea in the PUF resin system. The 13C NMR investigation showed that the synthesis process of PUF resin contained no free formaldehyde elements. Furthermore, the proportion of urea and methylolureas in the mixture to synthesis PUF resin were sufficient and incorporated well into the formulation by reacting with LMWPF units to form co-condensed methylene bridges. This study showed a new and useful method to synthesize PUF resin during the gluing process of manufactured Elaeis palm plywood which can also enhance the performance of Elaeis palm plywood panels for structural instead of utility grade applications. 相似文献
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以木质素为原料,在水相中合成一种适用于木材胶黏剂的木质素环氧树脂。为了考察木质素环氧化反应条件对木质素环氧树脂的羟基和环氧基的影响,以及对胶合板的胶合强度的影响,采用FT-IR和31PNMR对木质素环氧树脂结构进行表征,并用TG和DTG对木质素环氧树脂的热稳定性进行分析。结果表明,环氧化反应主要发生在酚羟基上,在反应过程中,相比环氧氯丙烷,NaOH的加入量对木质素环氧树脂结构和胶合板的胶合强度影响更大。随NaOH加入量增加,木质素环氧树脂中环氧基团逐渐增多,胶合板的胶合强度呈现先升高、后降低的趋势。当木质素的羟基与NaOH摩尔比为1:1时,由木质素环氧树脂制得的胶合板胶合强度达到最大,湿强度达1.61 MPa,超过国家标准II类板的要求(≥0.7 MPa)。采用扫描电镜研究了黏接机理,发现环氧化程度提高时,固化后的木质素环氧树脂的结构更加稳定且致密,导致胶合板的胶合强度也提高。但过高的环氧化程度会增大胶黏剂的粒径,导致胶黏剂与木板不能形成更好的机械互锁结构,从而降低胶合板的胶合强度。还进一步简化了木质素环氧树脂木材胶黏剂的合成工艺,使环氧化反应后的体系无需处理即可直接应用于木材胶黏剂,减少了胶合板生产工艺流程。此外,经过30天的储存期,胶黏剂黏合强度没有明显下降。通过与商业脲醛树脂木材胶黏剂对比,其黏接强度可以达到商业脲醛树脂的水平。 相似文献
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Xianfeng Mo Dongbin Fan Tefu Qin 《Journal of Adhesion Science and Technology》2013,27(22-23):2316-2326
The structure of ZnO-catalyzed phenol–urea–formaldehyde (PUF) resin at different synthesis stages was analyzed by liquid 13C nuclear magnetic resonance spectroscopy. The results showed that the general structure of ZnO-catalyzed PUF resin was almost the same as the control PUF resin. Addition reaction between phenol and formaldehyde mainly occurred at the first stage. Total methylol groups amount between phenols of the control resin was a little lower than that of the ZnO-catalyzed PUF resin. Co-condensation and self-condensation reaction occurred at the second stage. The preparation method of ZnO-catalyzed PUF resin favored the co-condensation reaction between phenol methylol groups and urea units, while self-condensation reaction dominated the control resin at the second stage. Formaldehyde completely reacted for both the control and ZnO-catalyzed PUF final resin. The total amount of methylol and methylene groups between urea units and phenols, respectively, was almost the same for the two final resins. The total quantity of methylol groups between phenols represented a continuing downward trend from the first stage to the final stage, and the amount of methylol group (p-Ph–CH2OH) of ZnO-catalyzed PUF resin was 30% more than that of the control resin. Total co-condensed methylene groups amount of ZnO-catalyzed PUF resin was greater than that of the control resin, which indicated that ZnO could make the urea units well incorporated into the co-condensed PUF resin. 相似文献