Scientific Research Report
Study on the preparation of low molecular weight PAA and dispersion performance of nano silica particles
Liu Ning1, Sun Jian2, Xia Zhean1, Li Xinxin1
(1.Key Laboratory of Specially Functional Polymeric Materials and Related Technology (Ministry of Education), East China University of Science and Technology, Shanghai 200237, China; 2. Hilong Petroleum Product Technology Services (Shanghai) Co., Ltd., Shanghai 200941, China)
【Abstract】The polymerization process of polyacrylic acid (PAA) aqueous solution was tracked by high-performance liquid chromatography with the constant current titration method. The effects of monomer concentration, system pH value, chain transfer agent amount, feeding time, initiator amount and reaction temperature on the molecular weight of PAA were systematically studied, and the controllable synthesis method for low molecular weight PAA was obtained. The effects of pH value, PAA molecular weight, and its mass fraction on the dispersion performance of nano silica particles were studied by orthogonal experiment with the prepared PAA as hyperdispersant. The research results showed that the concentration of monomer acrylic acid should not be too high and should be controlled at less than 30%. In order to obtain low molecular weight polymer, the monomer pH value should be less than 4.5. As the amount of chain transfer agent isopropanol increased, the molecular weight of PAA decreased. When the mass ratio of isopropanol to acrylic acid was 2.9 : 1.0, the molecular weight of PAA decreased to about 3 000. As the feeding time prolonged, the molecular weight of PAA gradually decreased and slowed down. Overall, it was advisable to control the feeding time at 120 minutes. As the initiator amount or reaction temperature increased, the kinetic chain length of PAA decreased, and the molecular weight correspondingly decreased. Multivariate analysis of variance showed that pH value had the greatest impact on dispersion effect. The optimal dispersion conditions for nano silica were determined as follows: the pH value was 7, the molecular weight of PAA was 5 210, and the mass fraction was 2.0%.
【Keywords】polyacrylic acid; hyperdispersant; low molecular weight; nano silica
Development of high performance polyimide-epoxy adhesive
Xu Xiaoqing, Yu Xinhai
(College of Chemistry and Chemical Engineering, Donghua University, Shanghai 201620)
【Abstract】In this study, 8 different formulations of polyimide-epoxy adhesive were prepared by changing the proportion of epoxy toughening agent (SRTEM-C21), curing agent (ECA-30, 2E4MI), and accelerator (B-30) through a series of chemical reactions. The viscosity properties, mechanical properties, electrical properties, water absorption properties, thermal properties, gelation time and apparent activation energy properties were comprehensively analyzed. The comprehensive analysis of mechanical, electrical, and thermal properties of 8 epoxy adhesive systems showed that J-3-2 adhesive had superior performance compared to other formulations, making it a more reasonable formulation with broad application prospects.
【Keywords】bismaleimide; epoxy resin; epoxy adhesive; adhesive preparation; adhesive property
Preparation of high molecular weight polyurethane acrylate and its performance modification in UV adhesive for PET substrate
Zheng Kexin1,2, Ling Lixia1, Wu Jianbing2, Wang Baojun1
(1.College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China; 2.Shanxi Research Institute of Applied Chemistry, Taiyuan 030024, Shanxi, China)
【Abstract】In response to the low surface tension of polyethylene terephthalate (PET) substrate and the low bonding strength of UV adhesive, using poly(neopentyl glycol adipate) (PNA), toluene diisocyanate (TDI), small molecule diols, and hydroxyethyl methacrylate (HEMA) as raw materials, a series of low viscosity, high molecular weight polyurethane acrylate oligomers (PUA) were synthesized by molecular structure design and molecular weight control. The structure and molecular weight of PUA were characterized by Fourier transform infrared spectroscopy and gel permeation chromatography. Then, the UV adhesive for PET substrate was prepared by using oligomers, monomers, photoinitiators, and phosphate ester as raw materials. The effects of initial n(NCO)/n(OH) value (R value), type and proportion of chain extenders, and types of soft and hard monomers on the viscosity, mechanical properties, volume shrinkage, and high and low temperature resistance of UV adhesive were investigated. The research results showed that when the initial R value was 1.6, the chain extender was propylene glycol, and the molar ratio of propylene glycol to PNA was 5:10, the molecular weight and viscosity of PUA were balanced, and the bonding strength of UV adhesive was the highest, reaching 4.09 MPa. When using isobornyl acrylate (IBOA) as the hard monomer and tetrahydrofuran acrylate (THFA) as the soft monomer in a certain proportion to prepare UV adhesive, the obtained UV adhesive had the best performance, with the tensile strength of 8.38 MPa, the elongation at break of 948.94%, and the curing volume shrinkage of 4.38%, the resistance to high and low temperature was relatively the best.
【Keywords】polyurethane acrylate; ultraviolet curing; PET substrate; soft and hard segment; adhesive
Development and Application
Study on the curing process of E-7 high temperature structural adhesive
Zhao Xueting1,2, Liu Xiangyu1,2, Zhang Chengxiang1,2, Zou Junjun1,2, Zhang Yuefeng1,2
(1.Shanghai Composite Material Science & Technology Co., Ltd., Shanghai 201112, China; 2.Shanghai Engineering Technology & Research Center of Aerospace Resin Based Composites, Shanghai 201112, China)
【Abstract】In order to study the characteristics of E-7 high temperature structural adhesive (E-7 adhesive) for engineering application, non isothermal differential scanning calorimetry (DSC) was used to study the reaction exothermic behavior and curing degree (α) curves at different heating rates (β), to obtain the reaction characteristic temperature (T). The theoretical curing temperature was obtained through T-β extrapolation method, and the activation energy (Ea) at different α values was calculated by using the Ozawa-Flynn-Wall method. The curing end time of adhesive solution was obtained at 60, 70 and 80 ℃ by isothermal DSC test. The research results showed that the Ea of E-7 adhesive increased with the increase of α, and the average activation energy of the reaction was 69 kJ/mol. The exothermic reaction of adhesive solution was completed at 140 min, 70 min and 46 min, respectively under isothermal DSC test at 60 ℃, 70 ℃ and 80 ℃, and the theoretical gelation point was 67 ℃. In addition, in combination with the gelation time test, viscosity-temperature characteristics and viscosity-time characteristics of adhesive solution, it was concluded that the parts to be bonded could be preheated to 60 ℃ during the actual adhesive brushing. At this temperature, the gelation time was 40 min, and the viscosity was low, which was convenient for the actual adhesive brushing operation. The research results of ultrasonic non-destructive testing equipment indicated that the bonding gap should be controlled within (0.10 ± 0.02) mm.
【Keywords】curing temperature; gelation time; viscosity; activation energy; bonding gap
Preparation of chlorinated polyether resin/nano-SiO2 modified acrylate composite emulsion and its application in water-based ink
Zhang Tianxiang, Pei Kemei
(School of Chemistry and Chemical Engineering, Zhejiang Sci-Tech University, Hangzhou 310018, Zhejiang, China)
【Abstract】The chlorinated polyether resin/nano-SiO2 modified acrylate composite emulsion was prepared by semi-batch seed emulsion polymerization with chlorinated polyether resin and vinyl nano-SiO2 as comonomers. The research results showed that: ⑴ The composite emulsion was successfully prepared. ⑵The dispersion of SiO2 particles in the emulsion film was relatively uniform, and the performance of chlorinated polyether resin/nano-SiO2 modified acrylate composite emulsion was stable. Compared with the similar product E0503 acrylate emulsion, the solid content of composite emulsion was higher, the viscosity was smaller, and the cured film was more flexible, which had certain extent of advantages in application. ⑶ When the composite emulsion and color paste were mixed at the ratio of 10∶4 to prepare the water-based ink, the ink layer performance could reach the average level in the industry. Compared with the water-based ink prepared with the similar product E0503 acrylate emulsion, the water-based ink layer with composite emulsion had obvious advantages in adhesion fastness and light aging resistance.
【Keywords】chlorinated polyether resin; nano-SiO2; acrylate emulsion; water-based ink
Special Topics and Review
Research progress on binder removal and recovery from spent lithium battery
Ma Yi, Cao Shiwei, Xing Yan, Cao Tengliang, Lin Liqun, Wang Jiajun, Wang Hong, Lu Feng, Jiang Lizhong
(Cangzhou Risun Chemicals Co., Ltd., Cangzhou 061113, Hebei, China)
【Abstract】Under the background of “Dual Carbon”, the tide of large-scale power battery retirement is approaching, and the green recycling of lithium-ion batteries (LIBs) has become an inevitable trend. Among them, the extraction of precious metals from cathode materials is the main purpose of recycling, and effectively stripping current collector aluminum foil, binder and acetylene black from cathode materials is the key to truly realizing the whole process of green recycling of cathode materials. However, the strong bonding force of the organic binder polyvinylidene fluoride (PVDF) hinders the effective separation of the cathode material and the current collector, which in turn affects the recovery and purification of the metal. Moreover, the HF gas generated by industrial direct crushing and roasting causes serious pollution to the environment. Therefore, the removal and recovery of lithium battery binder PVDF is imminent. In this paper, the physical and chemical properties, functions, and binding mechanisms of PVDF were reviewed, with a focus on the removal and recovery technologies of PVDF, providing theoretical basis and technical support for the green recovery of PVDF and cathode materials in the future.
【Keywords】cathode material; current collector; PVDF; separation; recovery
Research progress of polyurethane hot melt adhesive
Xu Jianing, Qian Bo, Wang Yuepeng, You Zhengwei
（College of Materials Science and Engineering, Donghua University, Shanghai 201620, China）
【Abstract】With the enhancement of global environmental awareness, solvent-free, green and environmentally friendly adhesives have attracted widespread attention. As one of the environmentally friendly adhesives, polyurethane hot melt adhesive has a large volume and rapid development, its structure has highly designability, and its performance can be adjusted in a wide range, which has been widely studied and applied. In this paper, the classification, molecular structure, bonding mechanism and performance characteristics of polyurethane hot melt adhesive were elaborated, its research progress in recent years was summarized, and finally its future development direction was prospected.
【Keywords】green and environmentally friendly; polyurethane; hot melt adhesive
Research on the standard of epoxy adhesive for prefabricated concrete segmental assembly
Wang Xianqian1, Zeng Bing2,3, Yao Shufang2,3, An Shaodu2,3
(1.Shenzhen Municipal Design & Research Institute Co., Ltd., Shenzhen 518029, Guangdong, China; 2.China Academy of Building Research, Beijing 100013, China; 3. CABR Testing Center Co., Ltd., Beijing 100013, China)
【Abstract】Epoxy adhesive is the key material in the joint of prefabricated segmental assembly structure, which affects the safety and durability of the structure. In this paper, the main testing items, technical indexes, testing methods and application scope of the relevant standards of splicing adhesive products at home and abroad were reviewed, the differences between these standards were compared. Based on the development of a new national standard for epoxy adhesive products used for prefabricated concrete segmental assembly, the ideas and key issues to be addressed in the standard formulation were proposed.
【Keywords】segment; epoxy adhesive; standard
Research progress of solventless polyurethane laminating adhesive
Liu Pengcheng, Hu Yang, Li Xing, Fu Xiaofang
(China Adhesives and Tape Industry Association, Beijing 100027, China)
【Abstract】Solventless polyurethane laminating adhesive has undergone several generations of product changes due to its safety, environmental protection and other performance advantages. Its performance is more optimized, and the product is more mature, continuously increasing its proportion in the laminating adhesive market. In this paper, the construction characteristics of solventless laminating adhesive, including the latest research progress of universal solventless single-component and two-component polyurethane laminating adhesive, water resistant and steam resistant two-component polyurethane laminating adhesive, and bio-based two-component polyurethane laminating adhesive were summarized. The current problems and status of solventless polyurethane laminating adhesive for flexible packaging were analyzed, and the future development direction was also prospected.
【Keywords】flexible packaging; polyurethane; solventless; laminating adhesive; two-component; water resistant and steam resistant