Special Topics Review

Research progress on resin matrix adhesive for bulletproof composite materials

Li Peng, Guo Xuebin, Zhang Jicai, Cao Shuliang, Ge Huixian, Zhang Tao

(CTA Hi-Tech Textiles Co., Ltd., Tianjin  301700, China)

【Abstract】With the widespread application of bulletproof composite materials in various fields, resin matrix, as its key component, had a decisive impact on the improvement of material protection effectiveness. The application practices and performance characteristics of various typical resin matrices, such as epoxy resin, phenolic resin, polyurethane resin, acrylic resin, and polyamide resin, in bulletproof composite materials were systematically reviewed in this article. It was believed that through continuous optimization of modification technology, different resin matrices showed significant advantages in mechanical properties, interfacial bonding strength, environmental adaptability, and energy absorption efficiency, but also had specific limitations. Finally, the future development of resin matrix-based adhesive for bulletproof composite materials was discussed. It was believed that with the breakthrough in the research and development of new resin matrices and the innovation of composite material design concepts, future research would focus more on the synergistic mechanism between resins and reinforcement materials, and strive to promote the development of bulletproof materials towards lightweight, multifunctional integration, and environmentally friendly directions, in order to accurately respond to the dynamic evolution of protective application needs.

【Keywords】bulletproof composite material; resin matrix; adhesive; bulletproof performance

Analysis of regulatory standards for adhesives used in food contact materials and products in China and major trading countries/regions

Pan Jingjing¹, Qiu Jinhua¹, Hou Yingliang², Yin Qin¹, Zhong Huaining¹, Zhu Yun², Chen Sheng¹

(1. Guangzhou Customs Technology Center, Guangzhou  510623, Guangdong, China; 2. Nongfu Spring Co., Ltd., Hangzhou  310024, Zhejiang, China)

【Abstract】The regulatory standard system for adhesives used in food contact materials and products in China and major trading partner countries/regions (EU, Germany, USA) was systematically reviewed in this article. Through in-depth analysis of specific regulatory requirements in various countries, including management mechanisms, product classification, permitted substance lists, production process standards, limit indicator settings, and product information labeling, and based on the key screening of high concern substances in adhesives, targeted compliance practice guidelines were provided for raw material production enterprises, adhesive manufacturing enterprises, and end use enterprises. Meanwhile, the future development trends in compliance management and safety assessment in the field of adhesives for food contact materials and products were prospectively explored.

【Keywords】food contact material and article; adhesive; regulatory standard; international trade; compliance

Research Report

Development of new colorless and transparent epoxy adhesive

Zhu Chenting, Yu Xinhai, Yu Kebo, Wu Haipeng

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

【Abstract】Multiple transparent epoxy adhesive systems (JQD-1~JQD-4) were successfully prepared by adjusting the proportion of three types of epoxy resin (bisphenol AF epoxy resin, bisphenol A epoxy resin, and silicone modified epoxy resin) in the adhesive system and the proportion of epoxy curing agent. The temperature-gel time, viscosity, electrical properties, curing reaction kinetics, UV visible light transmittance, etc. were systematically studied, and the formulation and preparation process were optimized. The research results showed that, ⑴ The viscosity of four formulations of epoxy adhesive decreased with increasing temperature. The viscosity of the formula system with a small amount of silicone modified epoxy resin added had a significant increase. ⑵ Temperature was the main factor affecting the gel time, and the increase of temperature significantly shortened the gel time of epoxy adhesive. The gel time of JQD-1 was relatively long due to trifluoromethyl in bisphenol AF epoxy resin. In addition, the epoxy curing agent QCA-48995 could effectively enhance the reactivity of the adhesive system, significantly reducing the gel time. ⑶ Bisphenol A epoxy resin was modified by introducing bisphenol AF epoxy resin and silicone modified epoxy resin, which effectively increased the activation energy and prolonged the gel time. The linear fitting results of the experimental data indicated that the curing process conformed to the Arrhenius behavior characteristics, which could provide a theoretical basis for optimizing the curing process parameters of epoxy adhesive. ⑷ Four formulations of epoxy adhesive showed stability in capacitance and dielectric loss at different frequencies. ⑸ The shear strength of four formulations of epoxy adhesive was greater than 10 MPa in the temperature range of -60~90 ℃. Among them, JQD-3 and JQD-4 basically met the requirements of heat resistance in the temperature test range from low temperature to 130 ℃. ⑹ The water absorption rate of four formulations of epoxy adhesive ranged from 0.073% to 0.697%, and all had excellent hydrophobic properties. Bisphenol AF epoxy resin usually had better water resistance compared to traditional bisphenol A epoxy resin. ⑺ Four formulations of epoxy adhesive all exhibited excellent colorless transparency, with JQD-3 showing the best transmittance of 91.42%. ⑻ Overall, the various properties of JQD-3 adhesive were superior to other formulations, and these characteristics constituted a relatively reasonable formulation that demonstrated broad prospects in its application.

【Keywords】bisphenol AF epoxy resin; epoxy adhesive; colorless and transparent epoxy adhesive; preparation; property

Preparation and performance study of CR/SBS composite modified asphalt

based on orthogonal experiment

Shang Hongfa¹, Fan Liang^2,4, Shen Quanjun¹, Ren Haiqing^3,4, Li Yongzhen^2,4, Bi Fei^2,4

(1.Shandong Hi-Speed Group Innovation Research Institute, Ji'nan  250014, Shandong, China; 2.Shandong Transportation Institute, Ji'nan  250102, Shandong, China; 3.Shandong Jianzhu University, Ji'nan  250101, Shandong, China; 4.Key Laboratory of Expressway Maintenance Technology, Ministry of Transport, Ji'nan  250102, Shandong, China）

【Abstract】By selecting different amounts of activated rubber powder, SBS content, and oil/rubber ratio, the five-factor four-level orthogonal experiment was conducted based on indicators such as penetration, softening point, ductility, and elastic recovery, and the relative optimal formula for twin-screw activated rubber powder/styrene-butadiene-styrene block copolymer (CR/SBS) composite modified asphalt was obtained through comprehensive analysis of mean and range. Through temperature scanning, multi stress creep recovery test, low-temperature bending creep, and fluorescence microscopy observation, it was compared and analyzed with activated rubber powder single modified asphalt (CR30% and CR40%) with different dosages, SBS modified asphalt, and matrix asphalt No. 70 to evaluate its performance. The research results showed that, ⑴ The optimal formula for CR/SBS composite modified asphalt was obtained through mean and range analysis of orthogonal experiment: activated rubber powder content was 30%, SBS content was 2.5%, and oil/rubber ratio was 1:6. ⑵ The CR/SBS composite modified asphalt under the optimal formula had higher complex shear modulus and rutting factor, smaller phase angle, and wider PG grading temperature range compared to other four types of asphalt, and its comprehensive performance was relatively the best. ⑶ When using activated rubber powder and SBS for composite modification of asphalt, the combination of activated rubber powder particles and SBS made the continuous layered network structure of rubber polymer more compact, resulting in better high-temperature deformation resistance and low-temperature cracking resistance of asphalt.

【Keywords】orthogonal experiment; activated rubber powder; modified asphalt; rheological property; SBS modified asphalt

Development of adhesive for laminated board

Tian Xueshen, Kuang Guangji, Xia Lingming, Wang Guanzhang, Wang Depeng, Yang Meng

(Gleihow New Materials Co., Ltd., Fushun  113004, Liaoning, China)

【Abstract】Ethylene based resin was synthesized by using a mixture of bisphenol A-type epoxy resin (E-51 and E-44) and methyl acrylic acid as raw materials. Through systematic optimization of styrene content, promoter content, talc powder content, and coupling agent selection, the laminated adhesive with high shear strength and high thermal deformation temperature characteristics was successfully prepared. The research results showed that, ⑴ As the mass fraction of epoxy resin E-51 increased, the hardness and thermal deformation temperature of laminated adhesive gradually increased, and the shear strength first increased and then decreased. When the mass fraction was 60%, it was relatively optimal, and the mechanical properties of the bonded laminated board were excellent and met relevant standards. This study determined that the epoxy resin was mainly composed of the mixture of E-44 and E-51, with the optimal mass fraction of E-51 being 60%. ⑵ As the amount of styrene added increased, the strength of the inner layer of laminated board first increased and then decreased. When the amount of styrene added was 35%, the crosslinking degree of adhesive was relatively highest, and the strength retention rate of the inner layer of the bonded laminated board after immersion in oil exceeded 80%. The final determination was that the addition of styrene was relatively optimal at 35%. ⑶ With the increase of accelerator cobalt isooctanoate and N,N-dimethyl-o-toluidine (DMA) added, the operation time of laminated adhesive gradually shortened, and the curing under low temperature condition was not affected. This study determined that when the addition amounts of cobalt isooctanoate and DMA were 1.0% and 1.2%, respectively, the laminated adhesive had both moderate operating time and good low-temperature operating performance. ⑷ As the amount of talc powder added increased, the shrinkage rate of laminated board gradually decreased, and the mechanical properties first increased and then decreased. This study determined that adding 30% talc powder was relatively optimal. ⑸ The introduction of coupling agent could effectively reduce the moisture content and conductivity of laminated board. By comparing three types of silane coupling agent, the results showed that KH-570 exhibited the most significant performance in reducing moisture content and conductivity. This study determined to use KH-570 as the coupling agent for the composite system.

【Keywords】laminated board; adhesive; vinyl resin; mechanical property; stable performance

Process and Application

Study on sandblasting surface treatment technology for bonding repair of metal structure composite materials

Yang Hailong^1,2, Xie Jinbiao^1,2,3, Zhou Jian^1,2, Liu Peng^1,2, Sun Yungang^1,2, Xuan Shanyong^1,2

(1.Wuhu State-Owned Factory of Machining, Wuhu  241007, Anhui, China; 2. Anhui Aeronautical Composite Maintenance Engineering Technology Research Center, Wuhu  241007, Anhui China; 3. Tsinghua University, Beijing  100084, China)

【Abstract】The surface treatment process for bonding repair of metal structure composite materials in narrow areas by implementing diverse surface treatment methods was explored in this article. Various surface treatment methods such as grinding, sandblasting, and coupling agents were studied and compared, and the bonding performance under different surface treatment process parameters was analyzed in depth. Furthermore, the intrinsic mechanism of surface treatment technology in improving bonding performance was analyzed from multiple dimensions such as surface morphology characteristics, contact angle size, and roughness level. On this basis, the surface treatment process was optimized to improve the bonding quality. The research results showed that, ⑴ Compared to untreated surface, sandblasting treatment had significant difference in roughness, while the improvement effect of grinding process on surface roughness was relatively limited. The roughness of the surface after sandblasting treatment showed a trend of first increasing and then decreasing. ⑵ Using too small or too large sandblasting mesh size for surface treatment was not conducive to improving the bonding quality. Moderate sandblasting mesh size could ensure sufficient wetting of the adhesive while forming good mechanical engagement, thereby maximizing the bonding performance. ⑶ With the increase of sandblasting mesh size, the contact angle on the material surface showed a trend of first decreasing and then increasing. ⑷ The sandblasting process could achieve better bonding performance. As the sandblasting mesh size increased, the shear strength first increased and then decreased. When using a surface treatment process with high sandblasting pressure and 30 mesh sandblasting particle size, the highest shear strength (up to 30.2 MPa) could be obtained. ⑸ A set of optimized surface treatment process parameters were successfully obtained, which were suitable for bonding repair of metal structure composite materials in narrow areas. The results of this study provided a basis for optimizing the bonding repair process of metal structure composite materials.

【Keywords】bonding repair of composite material; metal structure; adhesive; surface treatment; sandblasting; coupling agent

Study on bonding performance of polyurethane structural adhesive

in power battery pack of new energy vehicle

Liu Yongjun, Wang Ning, Bao Yuhuan, Zhang Mingjie, Yang Bowen, Wang Shuai

(BYD Auto Co., Ltd., Xi’an  710100, Shaanxi, China)

【Abstract】In response to the technical requirements for the connection of plastic-metal heterogeneous materials in power battery pack of new energy vehicle, the key influencing factors of bonding performance of polyurethane structural adhesive were systematically explored in this study. By designing tensile shear, vertical pull-out, and accelerated aging tests, the influence of substrate surface characteristics, adhesive layer thickness, ambient temperature, and hydrothermal aging on bonding strength was highlighted.The research results showed that, ⑴ The microstructure of substrate surface had a significant impact on the bonding strength. Due to its high surface roughness, the bonding strength of transparent PET could be further improved to 14.05 MPa after plasma surface treatment, with an increase of 16.69%. This indicated that optimizing surface roughness could effectively improve the bonding strength. ⑵ The thickness of adhesive layer had a nonlinear effect on the bonding strength. When the thickness of adhesive layer was 0.5 mm, the tensile shear strength and vertical pull-off strength of the sample were close to the maximum, reaching 14.2 and 15.7 MPa, respectively. When the thickness of adhesive layer was 3.0 mm, the tensile shear strength decreased by 47.89%, while the effect on the vertical pull-off strength was significantly smaller. ⑶ The analysis of temperature influence showed that polyurethane structural adhesive could ensure better bonding strength at lower ambient temperature under conventional use temperature, but excessively low temperatures (below 0 ℃) would significantly affect its tensile shear strength. High temperature environment may result in significant thermal stress at the bonding interface of dissimilar materials due to differences in thermal expansion coefficients, leading to a decrease in bonding performance. ⑷ The aging test revealed that under high temperature and high humidity conditions, the tensile shear strength of the sample showed a significant decreasing trend. Under cold and hot shock environment, there was no significant decrease in the tensile shear strength of the sample, and the sample placed in a low-temperature environment (-25 ℃) showed 27.95% improvement in performance after 1 000 hours of aging. ⑸ In summary, it was recommended to prioritize the use of surface roughened PET substrates for polyurethane structural adhesive in practical application, supplemented by plasma treatment process, strictly controlling the thickness of the adhesive layer (≤0.5 mm), and selecting corresponding protective strategies for service environment to enhance durability.

【Keywords】polyurethane structural adhesive; power battery pack; bonding strength; hydrothermal aging; plasma treatment

Synthesis of hyperbranched polyurethane resin and its application in polyurethane thermal conductive potting sealant

Liao Zhehui, Fang Zhangjian, Li Guifei

(Guangdong Pustar Material Technology Co., Ltd., Dongguan  523646, Guangdong, China)

【Abstract】Using polypropylene glycol (PPG2000), 4,4'-diphenylmethane diisocyanate (MDI), and boric acid as raw materials, hyperbranched polyurethane resin was prepared in this article. Then hyperbranched polyurethane thermal conductive potting sealant was prepared by using this hyperbranched polyurethane resin. The effects of different R values, boric acid content, hyperbranched resin content, and filler content in the formulation of hyperbranched polyurethane on the mechanical and thermal conductivity properties of potting sealant were studied. The research results showed that, ⑴ The shear strength and elongation at break of hyperbranched polyurethane thermal conductive potting sealant were closely related to the R value. When the R value was 1.8, the adhesive shear strength was the highest and the elongation at break was the lowest. ⑵ The increase in the amount of boric acid added to hyperbranched resin had a significant impact on the mechanical properties of thermal conductive potting sealant. ⑶ The content of hyperbranched resin in thermal conductive potting sealant also had a significant impact on the adhesive shear strength and elongation at break. When the content of hyperbranched resin was 12%, the shear strength reached its maximum value. ⑷ The amount of thermal conductive filler had a significant impact on the mechanical, electrical, and thermal conductivity properties of potting sealant. The appropriate maximum filling amount of filler should be controlled at around 75%. At this point, the potting sealant had good thermal stability.

【Keywords】polyurethane potting sealant; thermal conductivity; hyperbranched polyurethane

Study on the characteristics of baking room in the painting workshop

based on the curing performance of epoxy structural adhesive

Li Jiao¹, Liu Qingsong², Zhong Haiping², Zhang Ling³, Li Jia³

(1.School of Chemistry and Pharmaceutical Engineering, Chongqing Industry Polytechnic University, Chongqing  401120, China; 2.Chongqing Changan Automobile Co., Ltd., Chongqing  400023, China; 3.School of Electrical Engineering, Chongqing Industry Polytechnic University, Chongqing  401120, China)

【Abstract】In order to improve the bonding performance of epoxy resin structural adhesive in automobile body manufacturing, the strength variation trend and fracture morphology of bonding joint under different baking temperatures and time to determine the failure mode of joint were analyzed in this paper. The influence of different baking and curing process conditions on the bonding performance of car body sheet metal joint was explored. The research results showed that, ⑴ When baked at 170 ℃ for 20 min, the joint strength reached a peak of 27.74 MPa, and the fracture mode was almost 100% cohesive failure of the adhesive layer, indicating that the adhesive layer was uniformly cured and the bonding performance was good. ⑵ When the baking temperature was too high or too low, the degradation of the adhesive layer and insufficient curing could lead to a decrease in the strength of the bonded joint. At the same time, combined with the temperature tracking test of the baking room in a certain automobile painting workshop, it was found that the temperature distribution during actual production was uneven, resulting in insufficient curing of structural adhesive in some areas, which increased the risk of structural adhesive delamination during vehicle operation. ⑶ Optimizing the design of the baking room and airflow management, as well as improving the temperature adaptability of the adhesive, were key to ensuring the stable performance of structural adhesive in actual production. ⑷ Based on the fuzzy PID control algorithm, temperature regulation could achieve precise control of the baking room temperature, ensuring stable operation within the temperature range of 165-175 ℃ to meet the process requirements for baking and curing of structural adhesive used in automobile bodies.

【Keywords】epoxy resin; structural adhesive; curing process; painting and baking room

Material Science

Self-repairing microcapsule modified waterborne acrylic decorative coating

and performance verification

Ye Fen¹, Zhou Zelong²

(1.Jiuzhou Polytechnic, Xuzhou  221116, Jiangsu, China;

2.Xuzhou Jiantao Energy Co., Ltd., Xuzhou  221700, Jiangsu, China)

【Abstract】To solve the problem of cracks and fissures in the surface coating of building exterior walls, self-repairing microcapsule technology was innovatively introduced into the waterborne acrylic building coating system in this article. By modifying titanium dioxide with silane coupling agent KH-560, the anti UV aging performance and surface hardness of the coating were improved. At the same time, acrylic resin microcapsules were prepared by in-situ polymerization method to improve the weather resistance and dynamic damage repair ability of the coating. The influence of the addition amount of self-repairing microcapsule on the coating performance (such as glossiness, color difference, surface roughness, UV aging resistance, and self-repairing performance) was mainly explored. The research results showed that, ⑴ The addition of self-repairing microcapsules had a significant impact on the glossiness of the coating. Within the range of 0-6%, the addition of self-repairing microcapsules could improve the glossiness of the coating, with a peak glossiness of 47.8 GU at 6%. To ensure good glossiness of this self-repairing acrylic coating, the addition of self-repairing microcapsules should not exceed 6%. ⑵ When the amount of self-repairing microcapsules added was 4% or 6%, the color difference change of the coating was relatively good compared to the blank coating without self-repairing microcapsules added. ⑶ As the amount of self-repairing microcapsules added increased, the roughness of the coating continued to increase and the impact resistance improved. When the amount of self-repairing microcapsules added was 10%, the coating had the highest impact resistance, which was 7 kg/cm. ⑷ The addition of an appropriate amount of self-repairing microcapsules could help improve the UV aging resistance and crack self-repairing performance of the coating. When the self-repairing microcapsule dosage was 6%, the color difference of the coating before and after the UV aging resistance test was relatively small, at 5.69%, and the scratch width change rate of the coating was the largest, reaching 31.06%. ⑸ The self-repairing coating prepared in this experiment exhibited good performance and could provide new ideas for the repair of building exterior walls.

【Keywords】acrylic coating; self-repairing; microcapsule; glossiness; impact resistance