低物质的量比脲醛树脂的凝胶变化分析

doi:10.3969/j.issn.0253-2417.2022.02.013

摘要/Abstract

摘要：

以物质的量比为1:1的甲醛(F)、尿素(U)为原料，用“碱-酸-碱”法合成了稳定的低F/U的脲醛树脂(UF)，并考察了贮存时间、中性电解质(NaCl、MgCl₂)、酸性电解质(NH₄Cl、AlCl₃)对UF的影响，通过Zeta电位仪、激光粒度分析(LS)仪、扫描电镜-能谱(SEM-EDS)仪、场发射透射电镜(FE-TEM)对UF胶粒的贮存稳定性、电位稳定性及聚集情况进行了分析，进而揭示UF的凝胶规律。研究结果表明：UF的凝胶既有胶体性质的体现，同时可能也发生了化学反应。离子及游离甲醛均制约着UF的稳定性，聚集体尺寸的增长导致了UF凝胶的形成。在引入不同电解质的条件下，凝胶时间与电解质的种类有关。SEM-EDS和Zeta电位等测试表明，胶粒表面更高的离子物种含量，可能有助于胶粒的静电稳定；中性电解质对胶粒的稳定性影响有限，酸性电解质明显改变了胶粒的稳定性；酸性电解质提供的酸性条件，促进了可溶连续相中的单体及线性低聚物等之间的反应导致形成了更大尺寸的聚集体，进而凝胶提前。FE-TEM和PSD等的结果表明：UF的凝胶过程可能伴随着胶粒的融合，即小颗粒消失，大颗粒相应生长；同时伴随着低聚物等的消耗，最终发展成为更大尺寸的聚集体，直至最终凝胶。

关键词: 低物质的量比, 脲醛树脂, 电解质, 胶粒, 凝胶

Abstract:

Using formaldehyde and urea(F and U, molar ratio 1:1) as raw materials, stable urea-formaldehyde resin(UF) with low F/U was synthesized by "alkali-acid-base" method. The effects of storage time, neutral electrolytes(NaCl, MgCl₂) and acidic electrolytes(NH₄Cl, AlCl₃) on UF were investigated. The storage stability, potential stability and aggregation of UF colloidal particles were analyzed by Zeta potentiometer, laser particle size analyzer(LS), scanning electron microscope(SEM-EDS) and field emission transmission electron microscope(FE-TEM), by which the gel rule of UF was revealed. The results showed that the gel of UF not only embodied the colloidal properties, but also had chemical reaction. Both ions and free formaldehyde restricted the stability of UF. The increase of aggregate size led to the gel of UF. The gel time was related to the type of electrolyte. SEM-EDS and Zeta potential tests showed that the higher ionic species content on the surface of colloidal particles might contribute to the electrostatic stability of colloidal particles; neutral electrolytes had limited effect on the stability of colloidal particles, while acidic electrolytes obviously changed the stability of colloidal particles; the acidic conditions provided by acidic electrolytes promoted the reaction between monomers and linear oligomers in the soluble continuous phase, resulting in the formation of larger size aggregates, leading to the advance of gel. The results of FE-TEM and PSD showed that the gel process of UF might be accompanied by the fusion of colloidal particles. Namely, small particles disappear, while large particles grew accordingly, and eventually developed into larger aggregates until the formation of gel with the consumption of oligomers.

Key words: low molar ratio, urea-formaldehyde resin, electrolyte, colloidal particle, gel

中图分类号:

TQ35
O648.1

李吉, 张一甫, 熊涛, 孙鑫, 谢赛情. 低物质的量比脲醛树脂的凝胶变化分析[J]. 林产化学与工业, 2022, 42(2): 93-100.

Ji LI, Yifu ZHANG, Tao XIONG, Xin SUN, Saiqing XIE. Analysis of Gel Change of Urea-formaldehyde Resin with Low Molar Ratio[J]. Chemistry and Industry of Forest Products, 2022, 42(2): 93-100.

图/表 11

图1

图2

图3

图4

图5

图6

图7

表1

图8

表2

图9

参考文献 20

1	马玉峰, 龚轩昂, 王春鹏. 木材胶黏剂研究进展[J]. 林产化学与工业, 2020, 40 (2): 1- 15.
	MA Y F , GONG X A , WANG C P . Research progress of wood adhesives[J]. Chemistry and Industry of Forest Products, 2020, 40 (2): 1- 15.
2	顾继友. 我国木材胶黏剂的开发与研究进展[J]. 林产工业, 2017, 44 (1): 6- 9, 19.
	GU J Y . The development and research progress of domestic wood adhesives[J]. China Forest Products Industry, 2017, 44 (1): 6- 9, 19.
3	孙燕, 徐伟涛, 毛安, 等. 我国脲醛树脂制备技术研究概述[J]. 林产工业, 2020, 57 (1): 1- 4. doi: 10.3969/j.issn.1671-4911.2020.01.001
	SUN Y , XU W T , MAO A , et al. Simple introduction on preparation technologies of urea-formaldehyde resins in China[J]. China Forest Products Industry, 2020, 57 (1): 1- 4. doi: 10.3969/j.issn.1671-4911.2020.01.001
4	DONG Y H , GAO Q , ZHANG Y , et al. Study on curing behavior of low molar ratio urea-formaldehyde resins with different curing agents[J]. Advanced Materials Research, 2011, 150/151, 965- 968.
5	ZHANG S F , LI J Z , ZHANG J Z , et al. Study on properties of modified low molar ratio urea-formaldehyde resins(I)[J]. Advanced Materials Research, 2010, 113/114/115/116, 2016- 2020.
6	DESPRES A , PIZZI A . Colloidal aggregation of a minoplastic polycondensation resins: Urea-formaldehyde versus mela mine-formaldehyde and mela mine-urea-formaldehyde resins[J]. Journal of Applied Polymer Science, 2006, 100 (2): 1406- 1412. doi: 10.1002/app.23230
7	PRATT T J , JOHNS W E , RAMMON R M , et al. A novel concept on the structure of cured ureaformaldehyde resin[J]. The Journal of Adhesion, 1985, 17 (4): 275- 295. doi: 10.1080/00218468508081165
8	MOTTER W K. The formation of the colloidal phase in low mole ratio urea-formaldehyde resins[D]. Pullman: Washington State University, 1990.
9	FERRA J M M , MENDES A M , COSTA M R N , et al. A study on the colloidal nature of urea-formaldehyde resins and its relation with adhesive performance[J]. Journal of Applied Polymer Science, 2010, 118 (4): 1956- 1968.
10	LIU C , LUO J , LI X , et al. Effects of compounded curing agents on properties and performance of urea formaldehyde resin[J]. Journal of Polymers and the Environment, 2018, 26 (1): 158- 165. doi: 10.1007/s10924-016-0913-1
11	WIBOWO E S , PARK B D . Deter mination of crystallinity of thermosetting urea-formaldehyde resins using deconvolution method[J]. Macromolecular Research, 2020, 28 (6): 158- 167.
12	PARK B D , JEONG H W . Hydrolytic stability and crystallinity of cured urea-formaldehyde resin adhesives with different formaldehyde/urea mole ratios[J]. International Journal of Adhesion and Adhesives, 2011, 31 (6): 524- 529. doi: 10.1016/j.ijadhadh.2011.05.001
13	GAO S D , CHENG Z H , ZHOU X , et al. Unexpected role of amphiphilic lignosulfonate to improve the storage stability of urea formaldehyde resin and its application as adhesives[J]. International Journal of Biological Macromolecules, 2020, 161 (20): 755- 762.
14	李爱萍, 阚成友, 杜奕, 等. 脲醛树脂合成反应过程的FTIR研究[J]. 物理化学学报, 2006, 22 (7): 873- 877. doi: 10.3866/PKU.WHXB20060721
	LI A P , KAN C Y , DU Y , et al. Study on the evolvement of structure in synthesis of urea-formaldehyde resins by FTIR[J]. Acta Physico-chimica Sinica, 2006, 22 (7): 873- 877. doi: 10.3866/PKU.WHXB20060721
15	王春鹏, 赵临五. 脲醛树脂胶黏剂[M]. 北京: 化学工业出版社, 2005: 34- 60.
	WANG C P , ZHAO L W . Urea-formaldehyde Resin Adhesive[M]. Beijing: Chemical Industry Press, 2005: 34- 60.
16	郝志显, 李红, 李铮, 等. 线型脲醛树脂的半结晶模板化作用[J]. 化学学报, 2008, 66 (8): 860- 866. doi: 10.3321/j.issn:0567-7351.2008.08.005
	HAO Z X , LI H , LI Z , et al. Templating effect of semicrystalline urea-formaldehyde resin with linear molecular structure[J]. Acta Chimica Sinica, 2008, 66 (8): 860- 866. doi: 10.3321/j.issn:0567-7351.2008.08.005
17	PARK B D , JEONG H W , LEE S M . Morphology and chemical elements detection of cured urea-formaldehyde resins[J]. Journal of Applied Polymer Science, 2011, 120 (3): 1475- 1482. doi: 10.1002/app.33247
18	刘明. 几种典型水溶液分散体系的Zeta电位及其稳定性研究[D]. 武汉: 武汉理工大学, 2010.
	LIU M. Study on Zeta potential and stability of several typical aqueous solution dispersion systems[D]. Wuhan: Wuhan University of Technology, 2010.
19	党亚茹. 阳离子-π作用诱导芳香氨基酸反常盐溶效应及机理研究[D]. 上海: 华东理工大学, 2016.
	DANG Y R. Study on the effect and mechanism of abnormal salt solubility of aromatic amino acids induced by cation-π interaction[D]. Shanghai: East China University of Science and Technology, 2016.
20	李燕英. 脲醛螯合树脂对水体中Pb²⁺、Sr²⁺的吸附研究[D]. 南京: 南京理工大学, 2014.
	LI Y Y. Study on the adsorption of Pb²⁺ and Sr²⁺ in water by urea-formaldehyde chelating resin[D]. Nanjing: Nanjing University of Science and Technology, 2014.

样品 sample	6 h		24 h
样品 sample	ζ/mV	DLS/μm	ζ/mV	DLS/μm
UF	-26.24	1.64	-26.65	1.48
UF+NaCl	-22.40	0.95	-20.19	0.76
UF+MgCl₂	-16.87	1.30	-15.02	1.18
UF+NH₄Cl	-19.44	0.75	-21.00	0.47
UF+AlCl₃	5.82	2.61	4.83	6.08

时间 time	UF+NH₄Cl¹⁾			UF+AlCl₃
时间 time	羟甲基/% methylol	游离甲醛/% free formaldehyde	pH值 pH value	羟甲基/% methylol	游离甲醛/% free formaldehyde	pH值 pH value
0 h	8.50	0.24	8.38	8.50	0.24	8.38
1 h	6.28	0.10	4.96	6.85	0.15	5.18
2 h	3.96	0.06	4.55	5.06	0.12	4.83
3 h	2.30	0.05	4.32	3.26	0.09	4.42
4 h	—	—	—	2.90	0.08	4.11

[1]	杨欣欣, 郭伟, 蔡照胜, 黄旭娟, 王婷, 丁正青. 脱氢枞酸缩水甘油酯接枝羟丙基壳聚糖制备及性能研究[J]. 林产化学与工业, 2021, 41(6): 51-56.
[2]	卞辉洋, 扶艳荞, 陈李栋, 杨伟胜, 姚双全, 戴红旗. 疏水亲油木质纳米纤维素气凝胶的制备及表征[J]. 林产化学与工业, 2021, 41(5): 45-50.
[3]	张盖同, 宋晓丽, 杨福生, 南静娅, 储富祥, 王春鹏. 具有抗冻特性的水凝胶电解质的制备及其在固态超级电容器中的应用[J]. 林产化学与工业, 2021, 41(4): 51-61.
[4]	张盖同, 宋晓丽, 南静娅, 汪宏生, 储富祥, 王春鹏. 大豆蛋白水凝胶电解质的制备及在固态超级电容器中的应用[J]. 林产化学与工业, 2021, 41(3): 55-62.
[5]	王猛, 唐丽, 高莉, 曲荣芬, 廖头根, 刘鹤. 纤维素/聚乙烯醇复合气凝胶制备及其性能研究[J]. 林产化学与工业, 2021, 41(3): 95-102.
[6]	侯浩强, 孙文野, 李双宾, 苗祥森, 刘守新. 木棉基炭气凝胶的制备、表征及其吸附性能研究[J]. 林产化学与工业, 2021, 41(2): 47-54.
[7]	南静娅,张盖同,王利军,汪宏生,储富祥,王春鹏. 离子液体基凝胶电解质的制备及其在超级电容器中的应用[J]. 林产化学与工业, 2020, 40(4): 17-23.
[8]	伍锦秀,董勇,夏剑雨,陈妍,曹云峰,刘祝兰. 高吸液性木质纤维气凝胶的制备及表征[J]. 林产化学与工业, 2020, 40(3): 52-60.
[9]	宋伟杉,刘士瑞,赵雪,陈瑶,高建民. 疏水性木粉-SiO₂气凝胶复合材料的制备及其性能研究[J]. 林产化学与工业, 2020, 40(2): 93-98.
[10]	卢传巍,郭晓亮,蔡青云,王春鹏,储富祥,王基夫. 甲基丙烯酸化木质素磺酸钙/聚丙烯酰胺复合水凝胶的制备与性能研究[J]. 林产化学与工业, 2019, 39(6): 75-80.
[11]	陈妍,王梓鑫,李奇臻,夏剑雨,刘祝兰,曹云峰. 木质纤维吸油气凝胶的制备及性能[J]. 林产化学与工业, 2019, 39(4): 49-55.
[12]	孙熠昂,宗传晖,王飞,张纳,李爱香. 马来海松酸环氧树脂在纸基覆铜板中的应用[J]. 林产化学与工业, 2019, 39(1): 123-128.
[13]	孙佳明, 鄂雷, 马春慧, 李伟, 刘守新. N掺杂炭气凝胶的水热制备及其金属离子吸附性能[J]. 林产化学与工业, 2018, 38(4): 20-28.
[14]	张海波, 蒋建新, 高宏, 商士斌, 宋湛谦. 松香基聚丙烯酰胺水凝胶的药物释放性能及其动力学研究[J]. 林产化学与工业, 2018, 38(3): 25-32.
[15]	郑坤, 牛力, 刘玉鹏, 陈莹, 王春鹏, 储富祥. 高力学强度羟乙基纤维素/聚丙烯酸复合水凝胶的制备[J]. 林产化学与工业, 2018, 38(3): 41-47.