Wang Hao
School of Chemistry and Materials Engineering, Changshu Institute of Technology, Suzhou, Jiangsu
For polyvinyl acetal resin, it was found that urea has a good modification effect on polyvinyl acetal resin during the experimental process. Drawing on the modification method of thiourea cross-linked polyvinyl acetal glue, a compound modified polyvinyl alcohol polymer was prepared by solution polymerization through the modification effect of urea on polyvinyl acetal resin.
Polyvinyl alcohol, modification, modifier
The synthesis of polyvinyl acetal resin is cross-linked and polymerized by using the hydroxyl group in PVA molecule and the two carbonyl groups in glyoxal molecule under acidic catalytic conditions [1,2]. In practice, the cross-linking reaction between molecular chains occurs in a very short section of structural units inside the polyvinyl alcohol molecule [3].
Modified polyvinyl alcohol polymers were obtained by the formation of acetal structures under acidic conditions and the modification of specific groups of acetal polymers by urea [4].
The experiment is based on m PVA : m water : m glyoxal = 15:150:6 [1], and the usage of polyvinyl alcohol is constant. Glyoxal is selected as the main modifier, and urea is used as the modifier to modify the polyvinyl acetal resin binder to obtain a composite modified polyvinyl alcohol polymer.
In a four-necked flask equipped with a stirrer, thermometer, and drop funnel, add polyvinyl alcohol and water, and keep it at 95 ° C for 1h to dissolve it completely. Add hydrochloric acid dropwise to adjust the pH to 1.5. Cool down to about 80-85 ° C, slowly drop the specified amount of glyoxal within 30min, keep it for 1h, add sodium hydroxide solution dropwise to adjust the pH to 7-8, which is neutral, and then cool down to 65-70 ° C. After the temperature stabilizes, add a certain amount of urea, and react at a constant temperature of 65-70 ° C for 1h.
Through the study of glyoxal and urea composite modified polyvinyl alcohol, it is determined that under certain conditions, glyoxal/urea composite modified polyvinyl alcohol polymer can be prepared by solution polymerization to provide corresponding reaction conditions.
| serial number | References |
|---|---|
| [1] | Sun Youhong. Preparation of water-soluble polyvinyl acetal adhesive [J]. Journal of Nanjing Xiaozhuang University, 2009, 23 (3): 42-44.|
| [2] | ZHANG Changhua, ZHENG Xiang, CHEN Gao, Ge Wenxi. Study on synthesis of polyvinyl alcohol-glyoxal acetal resin (Anhui University of Technology SRTP Project, 08026) [J]. Shanghai Chemical Industry, 2008,33 (12): 16-18.|
| [3] | Zheng Youming, Hu Xiaoyong, Chen Yao. Preparation and application of glyoxal-modified polyvinyl alcohol protective colloid [J]. China Adhesives, 2012, 21 (10): 22-25,42.|
| [4] | ZHANG Changhua, GU Xupeng, QIAO Hongbin. Preparation of thiourea crosslinked polyvinyl acetal adhesive, China, 201110079419. 7 [P]. Anhui University of Technology, 2011.10.12.
