Special Topics Review

Research progress on the structural control strategies of nano-hierarchical structure MnO₂ and its catalytic oxidation of volatile organic compounds

Liu Jiali, Liang Chenxi, Wu Songhua, Wang Yujie

(BAIMTEC Material Co., Ltd., Beijing  100094, China)

【Abstract】A systematic review was conducted on the construction strategies of nano-hierarchical structure MnO₂, including morphology and defect control, crystal phase control, and composite structure design. The application of hierarchical structure MnO₂ in the catalytic oxidation of volatile organic compounds (VOCs) such as formaldehyde and benzene derivatives was explored, revealing the structural characteristics that affect catalytic activity in specific reactions. Finally, in response to the challenges faced in practical applications such as insufficient stability, poor anti toxicity, and large-scale preparation, future development directions were proposed to provide theoretical guidance for the development of efficient catalytic materials.

【Keywords】MnO₂; nano-hierarchical structure; volatile organic compounds; catalytic oxidation; review

Research progress of bio-based raw materials for polyurethane adhesive in the electronics industry

Xu Yuwen, Liu Liangjun

(Dongguan U-Bond Material Technology Co., Ltd., Dongguan  523837, Guangdong, China)

【Abstract】A systematic review was conducted on the research progress of bio-based materials for polyurethane adhesive used in the electronics industry, including single component reactive polyurethane hot melt adhesive and two-component polyurethane adhesive. Firstly, the reaction mechanisms of common single component reactive polyurethane hot melt adhesive and two-component polyurethane adhesive, as well as the bio-based research progress of the main components of the formula, i.e. polyols, isocyanates, and corresponding additives were introduced. The application potential of bio-based raw materials, such as castor oil, soybean oil, rapeseed oil, palm oil, tung oil, and other bio-based polyols, as well as bio-based isocyanates and non isocyanates, as polyurethane adhesive materials were further elaborated. Then, a comprehensive analysis was conducted on the performance of bio-based raw materials on single component reactive polyurethane hot melt adhesive and two-component polyurethane adhesive used in the electronics industry, including key performance indicators such as bonding strength, heat resistance, moisture resistance, and insulation. Finally, the future development trend of using bio-based raw materials for polyurethane adhesive in the electronics industry was discussed, and it was pointed out that future research directions would focus on improving performance, reducing costs, expanding application areas, and strengthening industrial development, which provide theoretical support and technical references for the widespread application of bio-based polyurethane adhesive in the electronics industry.

【Keywords】bio-based raw materials; single component reactive polyurethane hot melt adhesive; two-component polyurethane adhesive; electronics industry

Research Report

Study on the thermal aging mechanism of SBC hot melt pressure sensitive adhesive on thermoplastic polyolefin substrate

Wang Jinrui, Yao Yijia, Chen Nan, Zeng Yilong, Ding Hongmei, Fang Kai, Liu Zhiwei, Wang Chong, Xu Dazhou

(State Key Laboratory of Advanced Waterproof Materials, Beijing Oriental Yuhong Waterproof Technology Co., Ltd., Beijing  101300, China)

【Abstract】A basic formulation for hot melt pressure sensitive adhesive (HMPSA) composed of styrene block copolymer (SBC), tackifier resin, and cyclic oil was designed, and it was coated on thermoplastic polyolefin (TPO) substrate to obtain the self-adhesive TPO roll. Using the type of tackifier resin as a single variable, the effects of five types of tackifier resins with softening points around 100 ℃ on the viscosity, softening point, rheological behavior, and bonding properties of HMPSA were investigated. Furthermore, the changes in bonding properties, rheological behavior, and chemical composition of self-adhesive TPO rolls prepared with five types of tackifier resin formulations during thermal aging at 80 ℃ for 7 d were further tracked. The research results showed that, ⑴ Comparing the peel strength of HMPSA formulations prepared with 5 different tackifier resins before and after aging, it could be seen that after thermal aging at 80 ℃ for 7 d, the peel strength of HDCPD formulation decreased the most, with an attenuation rate of 48%. The HC5 formulation had the smallest degree of attenuation, with an attenuation rate of 13%. The peel strength of RE formulation increased by 20% compared to no treatment, but the highest value (peel strength after 1 d of thermal aging) decreased by 26%. ⑵ The infrared spectroscopy results showed that there was no significant change in the chemical composition of HMPSA before and after thermal aging, and oxidative degradation was not the main reason for the decrease in HMPSA peel strength. ⑶ The HMPSA of four petroleum resin formulations (HDCPD, A-HDCPD, HC5, and HC9) showed a continuous decrease in peel strength during thermal aging, while the rheological curve showed a continuous shift of glass transition temperature (T_g) towards the low temperature zone, a shift of flow point (T_flow) towards the high temperature zone, and an increase in storage modulus (G'). The HMPSA of rosin resin RE formulation system was quite unique, with peel strength first increasing and then decreasing with thermal aging, and T_g first increasing and then stabilizing, while G' continued to increase. The changes in rheological and peel properties showed a good correlation, indicating that the migration of tackifier resin and cyclic oil components in the formulation was the main reason for the decrease in thermal aging peel strength. ⑷ The rheological analysis results indicated that the migration tendency of five tackifier resins into the TPO substrate, from small to large, was as follows: RE＜HC5<A-HDCPD<HC9<HDCPD. ⑸ During the thermal aging process, the tendency of the tackifier resin in HMPSA to migrate into the TPO substrate was influenced by both the compatibility of the resin with SIS and TPO. The poorer the compatibility with SIS, the better the compatibility with TPO, making migration more likely to occur. On the contrary, migration was less likely to occur.

【Keywords】hot melt pressure sensitive adhesive; thermoplastic polyolefin; thermal aging; rheological behavior; migration

High-temperature bonding performance of nano filler enhanced polyurea adhesive

Gu Yunsong¹, Zhang Ping¹, Wu Yeping², Zhang Yinyu²

(1.Southwest University of Science and Technology, Mianyang  621010, Sichuan, China;2.Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang  621900, Sichuan, China)

【Abstract】Nano fillers were introduced in this study to restrict the movement of polymer chains and improve the bonding strength of polyurea adhesive at high temperature. The influence of different nano fillers on the thermal stability and linear coefficient of thermal expansion of polyurea adhesive was analyzed in details. The research results showed, ⑴ Specific content of nano fillers could significantly improve the thermal stability of polyurea samples, especially when adding 10% white carbon black or aminated carbon nanotubes, which could effectively reduce the linear coefficient of thermal expansion in the range of 50-150 ℃. ⑵ The addition of white carbon black enhanced the thermal stability of polyurea samples to a certain extent, but its effect on improving bonding performance was not significant. ⑶ When the amount of aminated carbon nanotubes added was 15%, excellent bonding performance was exhibited at 80 and 130 ℃, with the most significant improvement in bonding performance, showing excellent bonding effect on 304 stainless steel. These findings provided important theoretical basis and experimental support for the application of polyurea adhesive in high-temperature environments.

【Keywords】nano filler; polyurea adhesive; thermal stability; linear coefficient of thermal expansion; high-temperature bonding performance

Preparation and performance study of ionic liquid modified epoxy conductive adhesive

Zhao Dingwei, Liu Zhao, Meng Siqi, Jin Zezhu, Zhu Shuyan, Liu Hao, Chen Limin, Cui Zhiyuan

（Beijing SanTel Technology & Trading Corp., Beijing  100854, China）

【Abstract】A solvated ionic liquid (ILs) was synthesized by using tetraethylene glycol dimethyl ether and lithium tetrafluoroborate, and its structure was characterized by infrared spectroscopy. Then, the epoxy conductive adhesive was prepared by blending the synthesized ILs with bisphenol A-type epoxy resin, curing agent, silver powder, and other additives. The influence of ILs mass fraction on the viscosity, thermal stability, mechanical properties, and conductivity of conductive adhesive was investigated. The research results showed that, ⑴Infrared spectroscopy analysis of solvated ionic liquid proved the successful synthesis of ionic liquid without the generation of new substances. It was confirmed by differential scanning calorimetry that the synthesized solvated ionic liquid could promote the ring opening reaction of epoxy resin, shorten the curing time, and improve the curing efficiency. Scanning electron microscopy microstructure analysis further confirmed that ionic liquid could promote resin curing shrinkage, form a denser and more stable crosslinking density network, promoting the dispersion of silver powder in the epoxy resin matrix, and forming a homogeneous mixture. ⑵ Electrical performance analysis showed that as the mass fraction of ILs increased, the volume resistivity of conductive adhesive showed a trend of first decreasing and then increasing. ILs could promote higher curing shrinkage, making silver powder curing shrinkage more compact and promoting the formation of conductive pathways, as confirmed by scanning electron microscope test results. However, excessive ILs might hinder the curing reaction of free epoxy groups, resulting in incomplete curing, reduced resin shrinkage, and increased volume resistivity. ⑶ The mechanical performance test results showed that with the continuous increase of ILs mass fraction, the chip shear strength and lap tensile strength of conductive adhesive showed a trend of first increasing and then decreasing, and reached their maximum at an ILs mass fraction of 15%. ⑷ The thermal performance test results showed that the addition of ionic liquid increased the glass transition temperature of conductive adhesive, while reducing the linear coefficient of thermal expansion. The glass transition temperature and linear coefficient of thermal expansion were related to the molecular chain structure and crosslinking density of the polymer network. ILs promoted the formation of a dense and stable three-dimensional network structure of epoxy resin, improving its thermal properties. ⑸ Overall, the conductive adhesive modified with 15% ionic liquid in the resin system exhibited the excellent comprehensive performance. Due to the many excellent advantages of ionic liquid, it had shown potential application prospects in the field of conductive adhesive preparation.

【Keywords】solvated ionic liquid; conductive adhesive; thermal performance; electrical performance; mechanical performance

Process and Application

Research on high-temperature resistance shear properties of packaging adhesive for corrugated carton and formulation optimization

Chen Chuxiong¹, Li Shuang¹, Zhang Xiupeng¹,

Xu Feng¹, Zhang Tianjing^1,2, Liu Xinghai²

(1.Xiangyang Hongyan Industrial Co., Ltd., Xiangyang  441002, Hubei, China; 2. Electronic Information School, Wuhan University, Wuhan  430064, Hubei, China)

【Abstract】In order to solve the problem of white glue being greatly affected by temperature in industrial production, which is prone to debonding, elastic opening, and splashing of adhesive during the production of cardboard boxes, the packaging adhesive used for corrugated carton should have high-temperature resistance shear properties and rheological properties while maintaining its original viscosity. In this paper, vinyl acetate copolymer emulsion was used as the main raw material, calcined kaolin and boric acid were used as reinforcing agent and crosslinking agent respectively, and polyether defoamer was used to prepare packaging adhesive with high-temperature resistance shear properties. The single factor variable method was used to study the effects of factors such as kaolin, boric acid, water, and feeding method on the viscosity of adhesive solution and the adhesive film strength. At the same time, combined with the response surface test method, the inflection point was observed with viscosity and adhesive film strength as response values, and the influence of the components with significant influence in the formulation on viscosity and adhesive film strength under high temperature and high shear was studied, and then the optimal formulation was selected based on actual production. The research results showed that the optimal formulation for modified adhesive was 2% kaolin, 0.227% boric acid, and 4.498% water. The experimental results were similar to the model optimization prediction results, indicating that the design experiment based on response surface methodology had practical significance, and verifying the feasibility of using response surface methodology to study the high-temperature resistance shear properties and formulation optimization of packaging adhesive for corrugated carton.

【Keywords】boric acid; kaolin; response surface; packaging adhesive; high-temperature resistance; shear property

Preparation and properties of UV-curable polyacrylate medical conductive adhesive

Fan Yanchao, Gong Jingrong, Zhu Dongling, Luan Weiwei

(Hebei Kangchen Biotechnology Co., Ltd., Handan  056200, Hebei, China)

【Abstract】Using water-soluble monomer 2-acrylamido-2-methylpropanesulfonic acid (AMPS) as the main polymer, 1,2-propanediol as the solubilizer, N,N-methylbisacrylamide as the crosslinking agent, potassium carbonate as the neutralizing agent, potassium chloride as the electrical performance enhancer, conductive titanium dioxide as the auxiliary conductive agent, and 2-hydroxy-4'- (2-hydroxyethoxy)-2-methylphenylacetone as the photoinitiator, the conductive adhesive solution was prepared. After coating and UV curing, it could be directly made into medical conductive adhesive, and its structure and properties were characterized. The research results showed that, ⑴ After analyzing its structure using Fourier transform infrared spectroscopy and pyrolysis gas chromatography-mass spectrometry, it was believed that the target product had been successfully prepared. ⑵ When the dosage of AMPS was small, the structural strength of water-based polyacrylate conductive adhesive was low, which led to internal structural tearing of the adhesive layer when testing 180° peel force, resulting in low 180° peel force. When the amount of AMPS used was too large, the structure of the adhesive was too strong, and the pressure sensitive adhesive was not easy to adhere to the steel plate, which also led to low 180° peel force. When selecting AMPS mass fraction of 40%, the performance of the adhesive was relatively good. ⑶ When the dosage of plasticizer 1,2-propylene glycol was low, it could provide elastic deformation to the adhesive layer, making the surface of the adhesive layer more fully in contact with the substrate, and the peel force increased with the increase of 1,2-propylene glycol dosage. But when the dosage of 1,2-propylene glycol was too high, cohesive failure (internal fracture of the adhesive layer) was prone to occur at the interface, resulting in a decrease in peel force. The ratio of 21.2% for 1,2-propylene glycol was selected as the final formula. ⑷ At low dosage of crosslinking agent N,N-methylene bisacrylamide, the cohesion of the adhesive layer could be enhanced, and the peel force increased with increasing dosage. However, when the dosage was too large, the cross-linked network became too dense, hindering the movement of molecular chains, resulting in a decrease in peel force, and the peeling surface was prone to sudden interface separation. The crosslinking agent mass fraction of 0.13% was selected as the final process formula. ⑸ Under the relatively optimal screening conditions, using 2-hydroxy-4'- (2-hydroxyethoxy)-2-methylphenylacetone as the initiator of the adhesive solution, potassium chloride as the conductive agent, and nanoscale high-purity conductive titanium dioxide as the auxiliary conductive agent, the final medical conductive adhesive could have excellent electrocardiographic properties. ⑹ After being treated with a constant temperature of 55 ℃ for 30 days or frozen at -20 ℃ for 7 days, the electrocardiographic performance and adhesion of the electrocardiogram electrode made with the above formula conductive adhesive remained basically unchanged, indicating that the conductive adhesive had good weather resistance.

【Keywords】polyacrylate; conductive adhesive; UV curing; medical

Material Science

Preparation and mechanical properties of chitosan/PVA/nano SiC composite film

Zhang Weigang¹, Su Xinru², Tian Qingquan²

(1.Xi'an Manareco New Materials Co., Ltd., Xi'an  710077, Shaanxi, China;2.College of Chemistry and Materials Science, Weinan Normal University, Weinan  714099, Shaanxi, China)

【Abstract】Chitosan/polyvinyl alcohol (PVA) /nano SiC composite film was prepared by flow casting method using nano SiC as reinforcement and glycerol/polyethylene glycol as plasticizer. The effects of adding plasticizer and nano SiC on the structure and mechanical properties of composite film were investigated separately. The research results showed that, ⑴ Plasticizer could enhance the strength of hydrogen bonding on the composite film, and with the increase of nano SiC, the cross-linking reaction in the composite film was reduced. ⑵ Plasticizer enhanced the cross-linking reaction within the composite film, disrupted the original crystal structure of the composite film, and formed a new cross-linked network structure, thereby reducing the crystallinity of the composite film. By comparing the XRD patterns of chitosan/PVA and SiC, it was shown that the composite film had been successfully prepared. ⑶ The addition of plasticizer and nano SiC improved the mechanical properties of the composite film. When the amount of plasticizer added was 20%, the mechanical properties of the composite film were optimal. When the amount of nano SiC added was 0.02-0.03 g, the tensile strength of the composite film was relatively high, reaching a maximum of 37.2 MPa, and the elongation at break reached 136%. ⑷ The water absorption rate of the composite film showed a trend of first increasing and then decreasing with the increase of nano SiC content, and the addition of nano SiC particles changed the hydrophilicity of the water absorbing groups in the composite film.

【Keywords】chitosan; PVA; nano SiC; plasticizer; composite film; preparation; mechanical property

Preparation of primer for bonding polypropylene material

Chen Haigui¹, Zhang Zhiwen¹, Bian Feng¹, Zhou Yamin², Peng Min²

(1.Guangdong Pustar Adhesives and Sealants Co., Ltd., Dongguan  523646, Guangdong, China; 2.School of Chemical Engineering and Energy Technology, Dongguan University of Technology, Dongguan  523808, Guangdong, China)

【Abstract】A primer with different amounts of chlorinated polypropylene and silane resin was prepared by using 2,2'-dimorpholinyldiethyl ether (DMDEE), chlorinated polypropylene, KH-560, KH-570, and silane resin as raw materials. The influence of chlorinated polypropylene, silane resin, and construction temperature on the bonding properties of polypropylene material was discussed. The research results showed that, ⑴ The addition of chlorinated polypropylene had a promoting effect on the bonding of polypropylene material, but as the dosage continued to increase, the viscosity of the primer system increased, resulting in poor coating performance and affecting the wetting and penetration ability of the primer on the substrate surface. This weakened the interaction force between chlorinated polypropylene and polypropylene material, leading to a decrease in shear strength and cohesive failure of the adhesive. ⑵ The addition of silane resin increased the surface activity of polypropylene material and introduced active groups. However, when the concentration of silane resin was too high, it affected the wetting of the surface of polypropylene material by the primer, thereby affecting the bonding effect of the primer on polypropylene material. ⑶ At construction temperatures of -5 and 0 ℃, the coating performance deteriorated, affecting the wetting and penetration ability of the primer on the substrate surface, thereby affecting the bonding effect of the primer on polypropylene material. When the construction temperature was above 5 ℃, the shear cohesive failure of the primer on polypropylene material was ≥ 90%. ⑷ In summary, when w(chlorinated polypropylene)=3%, w(silane resin)=12% (relative to the total mass of the primer), and the construction temperature was above 5 ℃, the prepared primer had excellent bonding performance to polypropylene material.

【Keywords】polypropylene; bonding; silane resin; primer