Special Topics Review
Research progress of colorless and transparent epoxy adhesive at home and abroad
Zhu Chenting, Yu Xinhai
（College of Chemistry and Chemical Engineering, Donghua University, Shanghai 201620, China）
【Abstract】Colorless and transparent epoxy adhesive has broad application prospects in many fields due to its unique transparency and excellent mechanical properties. With the development of technology and the continuous growth of market demand, colorless and transparent epoxy adhesive has received increasing attention in fields such as aerospace, automotive industry, electronic and electrical, and optical instruments. The research progress, types, preparation methods, performance indicators, and application in different industrial fields of colorless and transparent epoxy adhesive were reviewed in this paper. In terms of the research and application of colorless and transparent epoxy resin, bisphenol A type, bisphenol F type, hydrogenated bisphenol A type epoxy resins, and other new colorless and transparent epoxy resins all exhibited unique properties. By adding various modifiers, fillers, or selecting different curing agents, the mechanical properties, heat resistance, transparency, and other key performance indicators of epoxy resin could be significantly improved. Subsequently, the market status and application areas were introduced, and finally, the future development prospects were discussed.
【Keywords】colorless and transparent epoxy adhesive; preparation process; performance indicator; application field
Research and application of bone glue
Yang Yuna1, Hou Qinge1, Gao Hongfang1, Xue Ping1, Jiang Bao1, Xu Haiyuan2
（1.Weinan Vocational and Technical College, Weinan 714026, Shaanxi, China; 2.Shaanxi JI YA ER Testing & Research and Development Co., Ltd., Weinan 714026, Shaanxi, China）
【Abstract】Bone glue is a natural polymer adhesive widely used in industries such as wood, packaging, and agriculture, with a broad market for promotion. Its production raw materials are widely sourced, the cost is low, and it is environmentally friendly and pollution-free. The research and current status of modification methods and application fields of bone glue were summarized in this article, and the advantages and disadvantages of bone glue as adhesive were pointed out. It was hoped that this could provide reference for related research on bone glue and expand its application scope.
【Keywords】bone glue; environmental protection; adhesive; packaging
Research Report
The influence of soft segment structure on the performance of waterborne polyurethane
Xu Yiping, Zhang Jiaqi, Zhai Ruixue, Zhou Chao
（School of Chemical Engineering, Changchun University of Technology, Changchun 130012, Jilin, China）
【Abstract】Using isophorone diisocyanate (IPDI) as the hard segment, 2,2-bis (hydroxymethyl) propionic acid (DMPA), and 1,4-butanediol (BDO) as the main raw materials, five different soft segment structures (PCDL, PCL, PBA, PTMG, and PPG) of waterborne polyurethane (WPU) were prepared by combining pre-polymerization and acetone methods, with polycarbonate diol (PCDL), polycaprolactone diol (PCL), poly(1,4-butanediol adipate) diol (PBA), poly(tetrahydrofuran) diol (PTMG), and polypropylene glycol (PPG) as polyols. The influence of soft segment structure on the thermal properties, mechanical properties, bonding performance, and water resistance of the materials was revealed. The research results showed that PCDL based WPU exhibited excellent thermal, mechanical, and water resistance properties, but its excessively high rigidity might limit its use in certain flexible applications. PCL and PBA based WPU exhibited balanced overall performance, making them suitable for application scenarios with certain requirements for thermal stability and mechanical properties. PPG based WPU was suitable for fields that required high flexibility due to its high flexibility and low glass transition temperature, but its thermal stability and water resistance needed to be further optimized.
【Keywords】waterborne polyurethane; soft segment; bonding performance
Study on the modification of boron nitride to acrylate thermal conductive structural adhesive
Liu Mei1, Ge Bingjie1, Qi Anjie1, Yu Zhuqing1, Xiang Shanglin1,2
(1.College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211816, Jiangsu, China; 2.Shandong Lihe New Material Technology Co., Ltd., Jining 272200, Shandong, China)
【Abstract】To solve the problems of difficult infiltration compatibility, poor dispersibility, and easy aggregation between boron nitride nanoparticles and polymer substrates, acrylic thermal conductive structural adhesive was prepared in this paper by using modified boron nitride (BN), epoxy acrylate oligomers, lauryl methacrylate (LMA), trifunctional acid ester (SR9051 NS), azobisisobutyronitrile (AIBN), and hydroquinone as raw materials, and its rheological properties, thermal conductivity, and bonding properties were characterized. The research results showed that the viscosity of thermal conductive structural adhesive and the thermal conductivity of its cured material increased with the increase of modified boron nitride amount. When the amount of modified boron nitride was 40%, the thermal conductivity of thermal conductive structural adhesive was 540% higher than that of the structural adhesive without boron nitride added. With the increase of modified boron nitride amount, the shear strength showed a trend of first increasing and then decreasing, among which the shear strength of 20%BN/SA thermal conductive structural adhesive could reach up to 15 MPa.
【Keywords】thermal conductive structural adhesive; modified boron nitride; mechanical strength; thermal conductivity
Effect of calcium sulfate whiskers on bonding strength and thermal properties of epoxy resin adhesive
Zhao Ming, Zhang Xue, Sun Mingming, Zhang Xugang, Zhang Bin, Li Jianhui, Wang Lei, Li Jinzi
(Institute of Petrochemistry, Heilongjiang Academy of Sciences, Harbin 150040, Heilongjiang, China)
【Abstract】WSR618 epoxy resin, AG-80 epoxy resin, and toughening agent were mixed in a mass ratio of 70∶30∶20 to form the main resin system. Dicyandiamide and organic urea were used as curing accelerators, and silane coupling agent and calcium sulfate whiskers filler were added to form the adhesive system. The effect of calcium sulfate whisker filler on the single lap shear strength of epoxy resin adhesive at different adhesive layer thicknesses was investigated, and the curing reaction heat, glass transition temperature (Tg), expansion coefficient, and thermal stability of the adhesive system with calcium sulfate whiskers added were studied. The research results showed that, ⑴ Adding calcium sulfate whiskers to epoxy resin adhesive could reduce the magnitude of the decrease in single lap shear strength of the adhesive as the adhesive layer thickened, and to some extent enhanced the shear strength of the adhesive under 0.5 mm and 1.0 mm thick adhesive layers. ⑵ Adding calcium sulfate whiskers could reduce the curing reaction heat of epoxy resin adhesive system and increased the peak curing reaction temperature of the system. ⑶ The addition of calcium sulfate whiskers reduced the Tg of the adhesive system. When the addition amount was 10 phr, the decrease in Tg of the system was very small. When the addition amount exceeded 10 phr, the decrease in Tg of the system began to increase. ⑷ Adding calcium sulfate whiskers could reduce the thermal expansion coefficient (<Tg) of the epoxy resin adhesive system. When the amount of calcium sulfate whiskers added was 50 phr, the thermal expansion coefficient of the adhesive system was 37.2 μm/(m·℃). ⑸ When the temperature of the adhesive system was less than 350 ℃, the mass was relatively stable. When the temperature exceeded 350 ℃, significant mass loss began to occur. As the amount of calcium sulfate whiskers added increased, the heat loss mass of the adhesive system gradually decreased at 800 ℃.
【Keywords】epoxy resin; adhesive; calcium sulphate whisker; thickness of adhesive layer
Preparation and performance study of polyurethane structural adhesive with full temperature range characteristics
Gong Hongliang
(Techstorm Advanced Material Co., Ltd., Shanghai 201400, China)
【Abstract】Two-component polyurethane structural adhesive was prepared by using polyol components (including small molecule chain extender 1,4-butanediol, trifunctional macromolecule polyether with a molecular weight of 5 000), isocyanate components (including specially formulated polyurethane prepolymers, carbodiimide modified liquefied MDI, crude MDI, etc.), and other additives (fillers, molecular sieve activation powder, defoamers, etc.). Its various properties (tensile strength, elongation at break, shear strength, storage modulus) and thermal performance analysis over a wide temperature range were tested. In addition, the influence of different chain extenders or crosslinkers on the performance of the full temperature range system was also studied. The research results showed that, ⑴ The polyurethane structural adhesive prepared by QWY-1 exhibited excellent low-temperature toughness and full temperature range characteristics. At low temperatures (-30 ℃), it had high intrinsic strength, reaching 29.67 MPa, and exhibited high fracture toughness, with elongation at break of about 330%. In addition, its mechanical properties were stable within the range of -40~80 ℃, without significant changes with temperature, which could avoid sudden changes in material properties caused by glass transition temperature. ⑵ By using different chain extenders or crosslinkers, polyurethane structural adhesive with different modulus gradients could be prepared in the full temperature range (QWY-1, QWY-2, and QWY-3 samples), with modulus of 57.52, 15.97, and 663.77 MPa at 25 ℃, respectively. Among them, QWY-3 adhesive sample exhibited excellent low-temperature toughness and high-temperature strength, with tensile strength of 12.23 MPa at 60 ℃ and elongation at break of 39.07%, demonstrating certain full temperature range characteristics.
【Keywords】full temperature range; polyurethane structural adhesive; glass transition temperature; storage modulus
Process and Application
Research on curing behavior and curing processability of isotropic conductive adhesive film
Wei Yunzhao, Zhao Meng, He Yingcui, Wu Jianwei, Wang Xuesong, Fu Gang, Zhao Yuyu
(Institute of Petrochemistry, Heilongjiang Academy of Sciences, Harbin 150040, Heilongjiang, China)
【Abstract】The chemical rheological properties of conductive adhesive film were measured by using rheometer, and the heat release curves at different heating rates were tested by using differential scanning calorimetry, followed by kinetic calculations. The effects of curing temperature and curing pressure on the conductivity and bonding properties of conductive adhesive film were systematically studied. The research results showed that, ⑴ The conductive adhesive film could be pressurized and positioned to achieve good wetting and bonding of the adhered material during the heating process. ⑵ The curing temperature was between 125-160 ℃, and the activation energy was about 109 kJ/mol. Within this range, the conductive adhesive film could achieve good curing and low volume resistivity. ⑶ Raising the curing temperature was beneficial for improving the conductivity of conductive adhesive film. ⑷ Increasing the curing pressure was beneficial for the infiltration of conductive adhesive film on the adhered surface and improved the shear strength.
【Keywords】conductive adhesive film; curing behavior; volume resistivity; curing process
Preparation of a polyurethane/epoxy modified PVC high-temperature curing weld sealant
Guo Meng, Zhao Zhaolin, Bian Feng, Jiang Hong
(Guangdong Pustar Material Technology Co., Ltd., Dongguan 523646, Guangdong, China)
【Abstract】A high-temperature curing weld sealant with excellent mechanical properties and no yellowing was prepared by using polyvinyl chloride (PVC) resin as the main raw material, and adding polyurethane resin, epoxy resin, etc. The effects of PVC resin, heat stabilizer, epoxy resin/curing agent amount proportion, and polyurethane resin on the mechanical properties, appearance yellowing, and bonding properties of sealant after high-temperature curing were discussed. The research results showed that high degree of polymerization PVC resin was preferred for high-temperature curing weld adhesive. Heat stabilizer could significantly improve the high-temperature curing performance of sealant, and the optimal addition amount should be controlled at around 2.5% (mass fraction). Introducing epoxy resin could improve the tensile strength and adhesion of sealant. The appropriate amount of epoxy resin added was around 6%, and the proportion of epoxy resin to curing agent was around 10:1. Adding polyurethane resin could significantly improve the mechanical properties and yellowing of sealant, and the appropriate addition amount was 2% to 4%.
【Keywords】weld sealant; high-temperature curing; PVC resin; yellowing resistance
Research on aging resistance of patching materials for porcelain cultural relics
Zhou Lu, Wang Xiaoyan
(Nanjing Museum, Nanjing 210016, Jiangsu, China)
【Abstract】Patching is a crucial step in the restoration process of porcelain cultural relics. The materials used for patching not only affect the subsequent coloring, pattern drawing, and glaze imitation techniques, but also affect the restoration of the complete structure of cultural relics and their long-term display effect. In this paper, three types of epoxy adhesive (Red Star 509, WD3620, and Hezhong AAA) was selected as base materials and kaolin as fillers to prepare patching materials. Through mechanical property testing, the relative optimal ratio of base materials/fillers was obtained. According to the different strength requirements of porcelain cultural relics, putty with different bonding strength was prepared for patching to avoid damage to the cultural relics. Afterwards, artificial accelerated aging tests were conducted on the optimal ratio putty to characterize its tensile shear strength, tensile strength, chromaticity, and contact angle before and after aging, and its aging mechanism was analyzed by Fourier transform infrared spectroscopy. The research results showed that, ⑴ Kaolin as filler could not only effectively fill the structural defects of epoxy adhesive and provide certain support, but also improve the bonding strength of epoxy adhesive. When the mass ratio of epoxy adhesive to kaolin was 100:55, the bonding strength and deformation resistance of the prepared putty were the best. ⑵ Among three types of putty prepared with epoxy adhesive, although the tensile strength of putty A was generally lower than that of putty B and putty C, based on the consideration of overall stability, its comprehensive aging resistance was the best and it was suitable for patching work in various environments. ⑶ The UV resistance and moisture resistance of putty B were the second, but after artificial accelerated aging test, its bonding strength and deformation resistance decreased significantly, making it suitable for temporary adhesive repair. ⑷ Temperature was the main influencing factor on the aging of epoxy patching materials, followed by ultraviolet light and humidity. Therefore, when displaying or preserving porcelain cultural relics repaired with epoxy adhesive, the primary condition was temperature control, and efforts should also be made to avoid ultraviolet light and humidity control.
【Keywords】porcelain; patching; epoxy adhesive; kaolin; aging resistance
Material Science
Study on performance influence of 90° peel strength of new lightning protection film
Sun Tianpei, Zhao Dafang, Li Jianheng, Liu Hansong, Li Bintai
（AVIC Composite Technology Center, AVIC Manufacturing Technology Institute, Beijing 101300, China）
【Abstract】The new lightning protection film was made of functional layers and adhesive film layers. Starting from the composition and structure of the protective film itself, the influence of the content and structural composition of adhesive film on its lightning protection performance was first studied. On this basis, the influence of the composition and structure of the protective film itself, as well as the conditions and processes for 90° peeling of the sample, on its 90° peel strength of new lightning protection film were studied. The research results showed that increasing the content of adhesive film was not conducive to improving its lightning protection performance, but it could increase its 90 ° peel strength. Adjusting the composition order of the functional layer and adhesive layer in the protective film did not significantly affect its lightning protection performance, but affected its 90 ° peel strength and failure mode. In addition, factors such as the paving direction of the protective film, the size of the aluminum sheet, and the processing method during sample preparation could have a certain impact on the 90 ° peel strength and failure mode of the lightning protection film.
【Keywords】90° peel strength; lightning protection performance; adhesive film content; lightning protection film
Study on testing method of curing degree of addition silicone rubber
Dai Fei, Wei Guocai, Wei Jingjing
[Kangda New Materials (Group) Co., Ltd., Shanghai 201419, China]
【Abstract】The curing degree of addition silicone rubber was investigated by using infrared spectroscopy, dynamic thermo mechanical analysis (DMA method), thermogravimetric analysis (TG method), hardness testing, shear strength testing, and tear strength testing, and an excellent curing degree testing method was obtained. The research results showed that, ⑴ The curing degree of addition silicone rubber could be characterized by different instruments (infrared spectroscopy, DMA method, TG method), and the relatively optimal curing time could be obtained. However, from the actual testing situation, there might be certain measurement errors in infrared spectroscopy and TG method testing, which required multiple repeated experiments for verification and were time-consuming. Therefore, it was recommended to use DMA method to test the curing degree of silicone rubber.⑵ By characterizing the curing degree of addition silicone rubber through mechanical properties(hardness method, shear strength method, tear strength method), it could be seen that in the products of this article, the hardness method was difficult to determine the complete curing time of silicone rubber, while the shear strength method and tear strength method could determine the optimal curing time. ⑶ The curing process parameters for the addition silicone rubber in this article were a temperature of 80 ℃ and a curing time of 3 hours, which could ensure complete curing of silicone rubber sample. The prepared silicone rubber samples had good adhesion to metals and some engineering plastics, meeting the bonding and sealing requirements of automobiles and other industrial devices.
【Keywords】addition silicone rubber; curing degree; testing method
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