Special Topics Review

Research progress on preparation and application of anaerobic adhesive

Lou Feipeng

(Shanghai Aircraft Manufacturing Co., Ltd., Shanghai    200120, China)

【Abstract】Anaerobic adhesive and bonding technology are widely applied in the aerospace and civil industries due to their advantages of low precision requirements during operation and cost-effectiveness. An overview of anaerobic adhesive, including its development history, composition, classification, and curing mechanism was provided in this paper. The performance modification direction and modification examples of anaerobic adhesive were analyzed in details, and the application and advantages of anaerobic adhesive in the aerospace field were summarized. Finally, the application process and curing influencing factors of anaerobic adhesive were elaborated, and future development prospects were discussed.

【Keywords】anaerobic adhesive; preparation; modification; application; bonding process

Research Report 

Preparation and properties of silane modified polyurethane resin

Guo Zhiqiang¹, Wu Linzhi¹, Wu Jinbi², Liu Xingjiang¹

(1. School of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou  450001, Henan, China; 2.Henan Duonaibao New Material Co., Ltd., Jiaozuo  454100, Henan, China)

【Abstract】A series of silane modified polyurethane (SPU) resins were prepared by using polytetramethylene glycol (PTMEG-1000), diphenylmethane diisocyanate (MDI-50), bis(3-trimethoxysilylpropyl)amine (TMSPMA, brand GX-1170), and N-phenyl-3-aminopropyltrimethoxysilane (brand Y-9669) as raw materials, and dibutyltin dilaurate (DBTDL) as a catalyst for the end-capping treatment of polyurethane (PU) prepolymers. It was cured by moisture at room temperature, and the structure and properties of the cured elastomer were characterized. The research results showed that, ⑴ The structural characterization indicated that aminosilane was grafted onto the PU system, confirming the successful synthesis of SPU resin. ⑵ Through mechanical testing of the cured elastomer, it was found that SPU-40 had the highest mechanical strength. Thermogravimetric analysis of the cured SPU-40 and PU elastomers showed that the 50% weight loss temperature of SPU-40 was about 32.6 ℃ higher than that of PU, indicating that the introduction of silane improved the thermal stability of PU. ⑶ As the content of Y-9669 increased, the regularity of polymer molecules gradually decreased, intermolecular entanglement intensified, and the glass transition temperature (T_g) gradually increased.⑷ As the proportion of Y-9669 increased, the viscosity of SPU resin gradually increased and the Shore A hardness gradually decreased. ⑸ During the crosslinking and curing process of siloxane, there was still a portion of Si—OH exposed on the surface of the polymer, and complete crosslinking has not been achieved. ⑹ As the proportion of GX-1170 silane decreased, the water contact angle on the surface of SPU elastomer gradually decreased, gradually changing from hydrophobic to hydrophilic. ⑺ The amount of silane added had an impact on the water absorption rate of the final SPU elastomer, further affecting its surface drying time and curing time. ⑻ Due to the regularity of the amino silane in GX-1170, while the amino silane in Y-9669 did not have regularity, as the amino silane in Y-9669 increased, the irregularity further increased and the diffraction peak gradually widened. Therefore, the soft and hard segments of the SPU film had poor regularity and were difficult to crystallize. ⑼ As the proportion of GX-1170 silane decreased, the tensile strength of SPU elastomer showed a trend of first increasing and then decreasing, while the elongation at break gradually increased. Under optimal conditions, the mechanical strength of SPU-40 elastomer was as high as 8.67 MPa, and the elongation at break was 75.1%. ⑽ Under hydrothermal aging conditions, there was no significant decrease in transmittance, but its mechanical strength gradually decreased. Polyurethane modified with silane retained its excellent acid and alkali resistance, while SPU elastomer had good acid and alkali resistance.

【Keywords】polyurethane; silane modification; moisture curing

Study on the preparation and properties of UV-curable hydroxylacrylate pressure sensitive adhesive

Huang Yi^1,2,3, Zhang Yihui³, Cai Jiehong³,Chu Yuehuan¹, Wang Linge²

(1.School of Chemistry and Materials Engineering, Huizhou University, Huizhou  516007, Guangdong, China; 2.School of Emergent Soft Matter, South China University of Technology, Guangzhou  510640, Guangdong, China; 3.Dongguan Polomo New Materials Technology Development Co., Ltd., Dongguan  523185, Guangdong, China;)

【Abstract】Using 2-ethylhexyl acrylate(2-EHA) as soft monomer, acrylic acid (AA) and hydroxyethyl acrylate (HEA) as polar monomers, methyl methacrylate (MMA) and cyclohexyl methacrylate (CHMA) as hard monomers, azobisisobutyronitrile (AIBN) as initiator, and ethyl acetate (EA) as solvent, hydroxylacrylate polymers were synthesized by free radical polymerization. After UV curing, pressure sensitive adhesive (PSA) was prepared, and it was subsequently characterized and analyzed. The effect of reaction temperature on the relative molecular weight and distribution of the polymer, the dosage ratio (mass ratio) of HEA/2-EHA, and the weight average molecular weight (M_w) of the polymer on the performance of the pressure sensitive adhesive, as well as the intrinsic relationship between bonding properties and viscoelasticity were investigated. The research results showed that, ⑴ Infrared characterization indicated that all monomers were involved in the reaction and the target product was successfully prepared. GPC testing of M_n, M_w, and PDI showed that as the reaction temperature decreased, M_n and M_w gradually increased, while PDI first increased and then gradually decreased. The actual T_g of polymer D was tested by DSC method to be -56.24 ℃. ⑵As the ratio of HEA/2-EHA increased, the maximum tensile strength and tensile strength gradually increased, the elongation at break gradually decreased, the 180° peel strength and initial tack gradually decreased, and the holding time gradually increased. Taking all factors into consideration, the pressure sensitive adhesive prepared from polymer D exhibited relatively optimal overall performance. ⑶As M_w increased, the elongation at break first decreased and then stabilized, the maximum tensile force and tensile strength first increased and then decreased, the 180° peel strength and initial tack gradually decreased, and the holding time first increased and then gradually decreased. Taking all factors into consideration, the pressure sensitive adhesive prepared from polymer D₂ exhibitd relatively optimal overall performance. ⑷ When the dosage ratio of HEA/2-EHA was 9/83, the M_w of polymer D₆ was 854.82 kDa, and the diluent contained 0.13% HDDA and 7% IBOA, the elongation at break of pressure sensitive adhesive P-D₆-2 was 1 396%. The maximum tensile force and tensile strength were 1.563 N and 0.313 MPa, respectively. The 180° peel strength, loop tack, and holding time were 17.36 N/25 mm, 27.62 N/25 mm, and 16.51 h, respectively.

【Keywords】UV curing; hydroxylacrylate polymer; pressure sensitive adhesive; bonding property; viscoelasticity

Development of a new solvent-free, colorless and transparent epoxy adhesive

Alizada Heydar, Qing Zhihui, Yu Xinhai

(College of Chemistry and Chemical Engineering, Donghua University, Shanghai  201620, China)

【Abstract】A new solvent-free, colorless and transparent epoxy adhesive was prepared by using hydrogenated bisphenol A epoxy resin and epoxy resin as the main components, and adjusting the ratio of hydrogenated bisphenol A epoxy resin, epoxy resin, and toughening agent. The viscosity, gelation time, electrical properties, impact strength, tensile shear strength, water absorption, curing reaction kinetics and UV-visible light transmittance of the epoxy adhesive system were systematically studied. The research results showed that, the prepared epoxy adhesive did not require the addition of solvents and had excellent reactivity, dielectric properties, water absorption, cold resistance and toughness. It also had excellent transparency and light transmittance, making it suitable for application in the field of optical instruments.

【Keywords】hydrogenated bisphenol A epoxy resin; epoxy resin; epoxy toughening agent; cold resistance; toughness; light transmittance

Process and Application 

Development of new high-performance epoxy adhesive for bulletproof

Li Yadong, Pan Xiulan, Yu Xinhai

(College of Chemistry and Chemical Engineering, Donghua University, Shanghai  201620, China)

【Abstract】Four types of epoxy adhesive systems were prepared by using two types of epoxy resin (multifunctional epoxy resin SINEP E80, epoxy resin SRTEM-50), polysulfone resin (SE3940), epoxy chain extender, etc., adding various epoxy toughening agents, and then adding curing agents and accelerators, and their properties were comprehensively analyzed. The research results showed that, ⑴ Among the four types of epoxy adhesive with different toughening agent ratios, PEJ-3 had moderate viscosity, making it easy to coat onto fibers, and had a lower apparent activation energy and faster curing reaction rate. ⑵ The capacitance of the four formulations of epoxy adhesive slowly decreased with increasing frequency, among which the capacitance of PEJ-2, PEJ-3, and PEJ-4 formulations of adhesive was between 4.6 and 5.4, all of which had good capacitance stability. The dielectric loss of four types of epoxy adhesive with different toughening agent ratios increased with frequency. Under an external electric field, the four formulations exhibited good electrical insulation performance. ⑶ The four formulations of epoxy adhesive exhibited excellent shear performance in the medium to low temperature range. Among them, PEJ-3 could still maintain high tensile shear strength within the testing range of -60 to 190 ℃. This formulation had good bonding strength and high and low temperature resistance, which could meet the basic requirements of resin-based strength and heat resistance of bulletproof composite materials. ⑷ The water absorption rates of four formulations all demonstrated good hydrophobicity, ranging from 0.20% to 0.60%. This characteristic made it widely applicable in situations where waterproofing and moisture resistance were required. ⑸ The PEJ-3 formulation composite material had an adhesive content of 37.4% and was not penetrated during the shooting test. The depression depth was only 18 mm, which was less than the standard 25 mm, indicating that the epoxy adhesive and fiber resin composite process could develop bulletproof composite materials with excellent comprehensive performance.

【Keywords】high-temperature resistance; low-temperature resistance; epoxy resin adhesive; bulletproof composite materials; adhesive performance

Preparation and properties of filler modified low viscosity and high-temperature resistance silicone rubber adhesive

Li Ran, Guo Anru, Hu Jie

(Aerospace Research Institute of Materials & Processing Technology, Beijing  100076, China)

【Abstract】In response to the performance and process requirements of silicone rubber adhesive in high-temperature ablation environments, a low viscosity phenyl silicone rubber base adhesive was synthesized, and the molecular weight distribution, phenyl content, and viscosity of base adhesive were characterized. The prepared base adhesive had a phenyl content of 22.5% to 23.8%, a viscosity of 6 530 to 11 500 mPa·s, and a volatile content of 0.30% to 0.37%. This indicated that both the viscosity and volatile content of base adhesive were at a low level, which was conducive to good processability. Subsequently, the room temperature vulcanizing silicone rubber adhesive was prepared by mixing phenyl silicone rubber base adhesive with white carbon black, iron oxide red, and chopped carbon fiber. A three-factor, three-level orthogonal experiment was used to investigate the effects of inorganic fillers on the viscosity, tensile shear strength, and temperature resistance of silicone rubber adhesive. The research results showed that, ⑴ From the range analysis of viscosity and tensile shear strength, it could be seen that white carbon black had the greatest impact on viscosity, followed by chopped carbon fiber. Adding white carbon black would increase both tensile shear strength and viscosity. Therefore, within the allowable range of viscosity, increasing the amount of white carbon black could improve tensile shear strength. ⑵ The range analysis of residual carbon rate showed that iron oxide red had a much greater impact on residual carbon rate than white carbon black and chopped carbon fiber. Iron oxide red could significantly improve the thermal stability of silicone rubber adhesive. When the amount of iron oxide red added was 10 parts, the swelling and exhaust during the heating process were significantly suppressed.

【Keywords】phenyl silicone rubber adhesive; filler; modification; white carbon black; iron oxide red; chopped carbon fiber; high-temperature resistance

Study on the aging resistance of butyl hot melt adhesive by anti-aging agent system

Huang Shiwen^1,2, Chen Jianjun², Sun Taolin¹, Zhang Guanqi², Huang Hengchao²

(1.South China University of Technology, Guangzhou  510641, Guangdong, China; 2.Guangzhou Baiyun Technology Co., Ltd., Guangzhou  510540, Guangdong, China）

【Abstract】The influence of the combination system of anti-aging agents RD, 4010NA, D, and MC on the aging effect of butyl hot melt adhesive was studied. The processing performance, mechanical properties, thermal stability, and water vapor transmission rate before and after aging (high-temperature thermal oxidative aging, wet-heat aging, thermal cycling aging, and UV aging) of butyl hot melt adhesive were investigated to determine the relatively optimal combination ratio. The research results showed that, ⑴ The combination use of anti-aging agents RD, 4010NA, D, and MC could improve the aging resistance of butyl hot melt adhesive, increased shear strength, reduced the increase in water vapor transmission rate, and maintained a cohesive failure rate of over 72%. Among them, the anti-aging agent RD/401NA/MC when used in combination had better aging resistance compared to other formulations. ⑵ Taking into account the situation before and after aging, the optimal addition amount of anti-aging agents in the system was m(RD): m(4010NA): m(MC)=3:3:2.5.

【Keywords】anti-aging agent; butyl hot melt adhesive; aging resistance

 Material Science 

Research on the bonding performance of different types of epoxy resin to metal substrates

Liang Haozhong¹, Lou Xingyuan¹, Feng Chaobo¹, Huang Xitong¹, Chen Jianjun^1,2, Huang Hengchao¹

（1.Guangzhou Baiyun Technology Co., Ltd., Guangzhou  510540, Guangdong, China; 2.Guangdong Baiyun Technology Co., Ltd., Foshan  528143, Guangdong, China）

【Abstract】Epoxy adhesive was prepared by using bisphenol A-type epoxy resin, polyurethane modified epoxy resin, or CTBN modified epoxy resin as resin raw materials, and adding additives such as dicyandiamide, substituted urea, calcium carbonate, and fumed silica. The adhesion of different types of epoxy resin (E-44, E-51, PUEP-A, PUEP-B, CTBN modified epoxy resin) to different metal substrates such as cold-rolled steel, 5052 aluminum alloy, 6061 aluminum alloy was explored, and one-component epoxy resin adhesive with good mechanical and bonding properties was developed. The research results showed that, ⑴ Bisphenol A-type epoxy resin had poor adhesion to metal substrates, while the addition of modified epoxy resin (polyurethane modified epoxy resin or CTBN modified epoxy resin) could improve adhesion. ⑵ There existed a modified epoxy resin content that made the cohesive strength of the adhesive equivalent to the bonding strength to the substrate. At this point, the adhesive's adhesion and mechanical strength reached a balance, and the bonding performance was the best. ⑶ The orthogonal experimental method was used to determine that the adhesive exhibited the best performance when the mass ratio of E-51, PUEP-A, PUEP-B, and CTBN modified epoxy resin was 2:1:1:1.

【Keywords】one-component; epoxy resin; adhesive; metal bonding.

Study on the influence of thermal oxidative aging temperature on the properties of polymer modified asphalt

Liu Cheng, Wu Xiaoying, Zhang Dongxu, Yao Qiang

[Sinopec (Dalian) Petrochemical Research Institute Co., Ltd., Dalian  116045, Liaoning, China]

【Abstract】Different mixing temperatures can lead to different initial aging states of asphalt, which may affect the long-term aging degree of asphalt and the service life of pavement. In order to compensate for the lack of existing research on the correlation between short-term aging temperature and long-term aging degree, the modified asphalt with different SBS contents (SBS accounted for 3.0%, 4.0%, and 4.8% of the total mass of modified asphalt, respectively) was prepared in this paper. The thermal oxidative aging temperature that covered three mixing techniques to perform short-term aging on modified asphalt was selected, and the long-term aging tests on modified asphalt with different degrees of short-term aging for different periods of time were conducted. 60 ℃ dynamic viscosity test, dynamic shear test, and infrared quantitative analysis test on SBS modified asphalt with different degrees of aging were conducted, and the influence of mixing temperature on the macroscopic and microscopic properties of asphalt at various stages of long-term aging was analyzed. The research results showed that, ⑴ Within the experimental time range, the aging degree of modified asphalt characterized by dynamic viscosity at 60 ℃ showed a pattern of low-temperature mixing < medium temperature mixing < high-temperature mixing, and the longer the pressure aging time, the greater the difference in aging degree. ⑵ When using the 60 ℃ rutting factor as the evaluation index for aging degree, the aging degree of low-temperature mixed asphalt was lower than that of medium temperature mixed asphalt in the early stage, and as time went on, the aging degree gradually approached that of medium temperature mixed asphalt. But the aging degree of both had always been lower than that of high-temperature mixed asphalt, and over time, the gap between them gradually widened. ⑶ When the mixing temperature reached 183 ℃, the degree of asphalt aging increased sharply, and as the pressure aging time prolonged, the growth trend of aging degree increased. In practical engineering, the mixing temperature should be controlled as much as possible not to exceed 183 ℃. ⑷ The carbonyl index and sulfoxide index of modified asphalt both increased with the prolongation of aging time, but the growth rate of carbonyl index gradually decreased, while the growth rate of sulfoxide index remained high.

【Keywords】polymer modified asphalt; mixing temperature; aging resistance; dynamic shear

Preparation and reliability study of thermally conductive silicone grease with ultra-low thermal resistance

Tan Yuemin¹, Wang Zhengfang², Li Shanji², Pang Wenjian¹, Ouyang Wenliang¹

(1. Guangzhou Baiyun Technology Co., Ltd., Guangzhou  510540, Guangdong, China; 2. School of Petroleum and Chemical Engineering, Guangzhou Institute of Technology, Guangzhou  510725, Guangdong, China)

【Abstract】A type of ultra-low thermal resistance and high thermal conductivity silicone grease was prepared by using dimethyl silicone oil and phenyl silicone oil as the matrix resins, and aluminum oxide, boron nitride, nano calcium carbonate, zinc oxide, and fumed silica as fillers. Its thermal conductivity, dielectric properties, and reliability were studied. The research results showed that, ⑴ The use of modified coupling agents to treat thermal conductive fillers and the addition of stabilizers could effectively improve the separation of oil and powder in the silicone grease, allowing the thermally conductive silicone grease to maintain good contact with the interface and thus maintain good thermal conductivity. ⑵ Viscosity studies showed that under cold and hot shock and "double 85" conditions, the viscosity of thermally conductive silicone grease decreased compared to the initial viscosity, and the change in viscosity with aging time was not significant, maintaining a relatively stable level overall. ⑶ Thermal resistance analysis showed that the thermal resistance of thermally conductive silicone grease could remain relatively stable after high-temperature aging. As the number of cold and hot shock cycles increased, the thermal resistance gradually increased. Under the "double 85" condition, the thermal resistance of thermally conductive silicone grease increased first and then decreased with aging time, reaching its maximum value after 250 hours of aging. ⑷ Under the same aging time, as the temperature increased, the thermal conductivity of thermally conductive silicone grease showed a trend of first increasing and then decreasing. With the extension of aging time, the thermal conductivity showed a significant downward trend, indicating that both thermal shock and "double 85" had a significant impact on the thermal conductivity of thermally conductive silicone grease. ⑸ The prepared thermally conductive silicone grease had ultra-low thermal resistance and could maintain a paste-like state after environmental aging. The maximum thermal resistance was at a relatively low level and had good thermal conductivity, which could meet the requirements of electronic and electrical products.

【Keywords】thermally conductive silicone grease; ultra-low thermal resistance; thermal conductivity; reliability