共查询到19条相似文献,搜索用时 93 毫秒
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《上海化工》1998,(20)
053 低毒脲醛树脂的合成机理 应用胶体理论,在不脱水、不增加过多改性剂的基础上,探索了低毒脲醛树脂胶的合成机理。所得胶达到GB/T14372-93要求,制得的刨花板满足GB/T4897-92A类板一等品要求,甲醛释放量达到欧洲En级。 054 改性脲醛树脂胶粘剂的研制 利用聚乙烯醇缩甲醛树脂在酸性条件下与大分子脲醛树脂进一步交联,合成了改性脲醛树脂胶粘剂。分步加入尿素,降低了脲醛树脂中的游离甲醛含量,提出了工艺条件及影响合成的因素。 055 脲醛树脂低醛胶制备工艺进展 提出了脲醛树脂胶粘剂的低醛化控制理论。认为提高树腐化反应平衡常数是最理想的控制手段,也是脲醛胶生产工艺改进的方向。 056 低游离甲醛含量脲醛树脂胶粘剂的合成 相似文献
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《上海化工》1998,(21)
063 低毒脲醛树脂的合成机理 应用胶体理论,在不脱水、不增加过多改性剂的基础上,探索了低毒脲醛树脂胶的合成机理。所得胶达到GB/T14372-93要求,制得的刨花板满足CB/T4897-92A类板一等品要求,甲醛释放量达到欧洲En级。 054 改性脲醛树脂胶粘剂的研制 利用聚乙烯醇缩甲醛树脂在酸性条件下与大分子脲醛树脂进一步交联,合成了改性脲醛树脂胶粘剂。分步加入尿素,降低了脲醛树脂中的游离甲醛含量,提出了工艺条件及影响合成的因素。 055 脲醛树脂低醛胶制备工艺进展 提出了脲醛树脂胶粘剂的低醛化控制理论。认为提高树脂化反应平衡常数是最理想的控制手段,也是脲醛胶生产工艺改进的方向。 056 低游离甲醛含量脲醛树脂胶粘剂的合成 相似文献
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脲醛树脂木材胶粘剂的耐湿抗候性能还不能完全适合建筑业方面的某些要求,因甲醛含量减少到一定量时,胶粘剂的耐湿性就要降低,为了改进刨花板的抗湿性能,本文介绍了用三聚氰酰胺、酚醛树脂和二异氰酸脂来改性脲醛树脂胶,并研究了如何评价不同胶粘剂的耐湿性能,对各种胶粘剂进行了试 相似文献
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我国木材胶粘剂发展概况 总被引:2,自引:0,他引:2
综述中国木材胶粘剂概况.报告了脲醛树脂、酚醛树脂、三聚氰胺-甲醛树脂、单宁胶、本素胶、木材的本体聚合等胶粘剂与粘合技术的改进,并提出有关建议。 相似文献
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改性脲醛树脂胶粘剂的研究 总被引:8,自引:1,他引:8
主要利用混合改性剂,改进生产工艺以及施胶时加入填料等方法研究脲醛树脂胶粘剂的游离甲醛含量,剪切强度、耐水性等问题,得到低毒,综合性能良好的胶粘剂。 相似文献
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环保型脲醛胶的制备与性能研究 总被引:5,自引:0,他引:5
利用自制的甲醛捕捉剂和酸性固化剂对脲醛树脂胶粘剂进行改性,并通过喷雾干燥工艺研制出环保型脲醛粉状树脂胶粘剂。还研究了不同物质的量比、缩聚阶段多次加料不同物质的量比、反应温度、甲醛捕捉剂等实验条件对脲醛树脂胶粘剂性能的影响。制备的脲醛树脂胶粘剂性能经测试达到了国家标准。 相似文献
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铸造用糠醇改性脲醛树脂中游离甲醛的研究 总被引:3,自引:1,他引:2
本文分析了糠醇改性脲醛树脂中游离甲醛产生的机理,介绍了几种降低游离甲醛的可行方法。并提出了一种低游离醛糠醇改性脲醛树脂的合成方法。 相似文献
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Ya-qing Liu Yu Tian Gui-zhe Zhao You-yi Sun Fu-tian Zhu Yang Cao 《Journal of Polymer Research》2008,15(6):501-505
Traditional method of synthesizing urea-formaldehyde (UF) resins is condensation polymerization with formaldehyde and urea
in aqueous solution, which leads to the low resistance of UF resins against the influence of water and moisture and results
in the high formaldehyde emission. A new method of melt condensation polymerization was used to synthesis UF resin by paraformaldehyde
with urea. Fourier-transform infrared spectroscope and Carbon-13 nuclear magnetic resonance were performed to elucidate the
uron rings structural characteristics of UF resin by the synthetic route. The stability during storage and application were
characterized by measuring concentration of methanol and free formaldehyde, and DSC and TG analysis, respectively. The results
show that UF resin synthesized by melt condensation polymerization has lower content of free formaldehyde, high thermal stability
and better stability during storage. 相似文献
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Urea‐formaldehyde (UF) resins are prone to hydrolysis that results in low‐moisture resistance and subsequent formaldehyde emission from UF resin‐bonded wood panels. This study was conducted to investigate hydrolytic stability of modified UF resins as a way of lowering the formaldehyde emission of cured UF resin. Neat UF resins with three different formaldehyde/urea (F/U) mole ratios (1.4, 1.2, and 1.0) were modified, after resin synthesis, by adding four additives such as sodium hydrosulfite, sodium bisulfite, acrylamide, and polymeric 4,4′‐diphenylmethane diisocyanate (pMDI). All additives were added to UF resins with three different F/U mole ratios before curing the resin. The hydrolytic stability of UF resins was determined by measuring the mass loss and liberated formaldehyde concentration of cured and modified UF resins after acid hydrolysis. Modified UF resins of lower F/U mole ratios of 1.0 and 1.2 showed better hydrolytic stability than the one of higher F/U mole ratio of 1.4, except the modified UF resins with pMDI. The hydrolytic stability of modified UF resins by sulfur compounds (sodium bisulfate and sodium hydrosulfite) decreased with an increase in their level. However, both acrylamide and pMDI were much more effective than two sulfur compounds in terms of hydrolytic stability of modified UF resins. These results indicated that modified UF resin of the F/U mole ratio of 1.2 by adding acrylamide was the most effective in improving the hydrolytic stability of UF resin. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
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Zhigang Wu Guanben Du Ming Cao Xuedong Xi Jiankun Liang 《Journal of Adhesion Science and Technology》2016,30(24):2655-2666
The characteristics of UF resin prepared with concentrated formaldehyde were studied in this paper. With the molar ratio F/U = 1.1, the UF resin prepared with concentrated formaldehyde showed better mechanical properties than that with formalin. The 13C-NMR and FTIR results indicated that there were more methylene groups, ether groups and urons in a UF resin system prepared with concentrated formaldehyde than those in a normal UF resin. The differential scanning calorimetry and DMA results showed that the curing temperature of UF resin with concentrated formaldehyde was lower than that of a normal UF resin. UF resin with concentrated formaldehyde showed worse thermal stability and higher thermal decomposition temperature. 相似文献
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弱酸性条件合成脲醛树脂工艺的探讨 总被引:1,自引:0,他引:1
探讨了在弱酸性条件下合成低甲醛释放量的脲醛树脂工艺的可能性。同时,对不同pH值条件下合成脲醛树脂的工艺及其性能进行了研究,并采用傅立叶红外光谱和化学方法对脲醛树脂的官能团进行了分析,同时定性分析了不同pH值条件下合成树脂的热学性能。研究表明在弱酸性条件下合成脲醛树脂的树脂性能和其胶合板的力学性能达到国家标准并且其胶合板甲醛释放量达到GB/T17657—1999中的E,级标准。弱酸性条件下合成脲醛树脂的工艺不仅能降低生产成本,还能生产性能优异的脲醛树脂胶黏剂。 相似文献
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Urea-formaldehyde (UF) resin with excellent intrinsic flame retardancy, high strength, and low cost has been widely used as adhesives, coatings as well as molding compounds, and it is a challenge to prepare UF resin with combined properties of high toughness/strength and low formaldehyde emissions. In this work, glutaraldehyde was introduced into the synthesis system of UF resin to partially replace formaldehyde, and urea-glutaraldehyde-formaldehyde (UGF) copolycondensation resin was prepared. It was found that glutaraldehyde participated in additional/condensation reactions of UF resin, and the crosslinking reaction of UGF resin was hindered with higher curing activation energy than that of neat UF resin. Due to the controllable curing kinetics and introduction of long methylene chains, UGF resin presented relatively low crosslinking density, and under external force, it underwent distinct yielding before fracture and many yield folds appeared on the fractured surface, showing high toughness and strength. Compared with neat UF resin, the tensile strength, elongation at break, impact strength, and critical stress intensity factor (KIC) of UGF resin increased by 26%, 42.30%, 14.6%, and 30%, respectively. Meanwhile, the free formaldehyde emission for UGF resin decreased by 47.5%, meeting the requirement of E0 grade. Such developed eco-friendly UGF resin exhibited promising application potentials. 相似文献