Scientific Research Report

Preparation and properties of filled silicone-based thermal conductive gel

Shang Tianyu, Zhang Chenxu, Ren Linlin, Zeng Xiaoliang, Sun Rong

(Shenzhen Institute of Advanced Electronic Materials, Shenzhen  518100, Guangdong, China)

【AbstractTaking silicone-based thermal interface materials as the research object, a series of filled silicone thermal conductive gel samples were prepared by using silicone oil with different viscosity ratios as the matrix, and alumina and zinc oxide as the thermal conductive fillers. The effects of gel composition on the mechanical properties, thermal conductivity, dispensing properties of the materials were investigated, respectively. The research results showed that the thermal conductivity of the prepared silicone thermal conductive gel was mainly affected by the thermal conductive filler. When the proportion of high-viscosity vinyl silicone oil was 50%, the thermal conductive gel had good properties, with the tensile strength, elongation at break, Shore hardness, thermal conductivity and extrusion rate reaching 0.37 MPa, 184%, 63.42, 2.90 W/(m•K) and 106.4 g/min, respectively. In addition, the thermal conductive gel samples in this study performed well in high temperature and high humidity environments and in hot and cold cycle tests, which could meet the requirements of the industry and have good application prospects and application values.

【Keywordsthermal interface materials; silicone gel; thermal conductivity; organic silicone


Preparation and properties of non-isocyanate polyurethane curing agent

Song Caiyu, Guo Yuting, Yuan Zhigang, Xie Tianyi, Li Jinzi, Sun Mingming, Zhang Bin, Zhang Xugang

(Institute of Petrochemistry, Heilongjiang Academy of Sciences, Harbin  150040, Heilongjiang, China)

Abstract】The cyclic carbonate compound (RDGEC) was synthesized by using resorcinol diglycidyl ether as raw material through CO2 insertion method. A series of non-isocyanate polyurethane (NIPU) curing agent was prepared by polymerizing it with polyether amine (D230) and adjusting the ratio of reactants. The curing kinetics of the blended system of NIPU and bisphenol A epoxy resin (E-51) was investigated in details, and the bonding properties, thermal mechanical properties, thermal stability, and fracture surface microstructure of cured samples were studied. The research results showed that RDGEC and NIPU curing agent were prepared successfully. Adjusting the reaction ratio of RDGEC and D230 had little effect on the curing reactivity of NIPU, but the toughness degree of the curing system could be effectively changed, and the curing process was determined to be 50 ℃/2 h + 100 ℃/2 h. The blended curing system of NIPU and E-51 had excellent bonding properties on aluminum alloy. When adjusting the ratio of RDGEC and D230 to 1∶1.75, the shear strength at 25 ℃ and 70 ℃ were 36.98 and 14.51 MPa, respectively, the 90° peel strength at 25 ℃ reached 6.08 kN/m, with the bonding properties reaching the best. This series of cured samples exhibited excellent thermal mechanical properties and thermal stability.

Keywords】non-isocyanate polyurethane; epoxy curing; bonding property; thermal stability


Study on curing of modified acrylate adhesive for FPC

Chen Wei1,2, Chen Wenqiu1,2,3, Yu Yang1,2, Zhang Xueping1,2,3, Li Zhenlin1,2,3, Fan Heping1,2,3

[1. HAISO Technology Co., Ltd., Wuhan  430074, Hubei, China; 2. HAISO EM (Wuhan) Ltd., Wuhan  430074, Hubei, China; 3. Hubei Research Institute of Chemistry, Jianghan University, Wuhan  430056, Hubei, China]

Abstract】When modified acrylate adhesive was applied to flexible printed circuit board (FPC) and its substrates, the degree of curing had a decisive influence on the performance. In this paper, taking the self-made epoxy resin modified acrylate adhesive as an example, the kinetic behavior of its non-isothermal curing was analyzed theoretically by dynamic differential scanning calorimetry (DSC), in order to study its storage stability at room temperature and the process conditions of high temperature curing. Then, its curing reaction process at room temperature and the temperature range of 125-300 ℃ was investigated by Fourier transform infrared spectroscopy (FT-IR) to ensure the curing performance or effect of the adhesive applied to the thermosetting adhesive film/sheet of FPC. The research results show that, ⑴ The curing kinetics equation of the modified acrylate adhesive was determined by non-isothermal DSC test, from which it was deduced that its reaction rate constant K value was as low as the 10-5 min-1 level and below under the conventional storage temperature of 10-50 ℃, exhibiting excellent B-order stability. At the same time, the K value at 180 ℃ and above reached the 10-1 min-1 level, which could meet the requirements of rapid curing by high temperature baking. ⑵ Based on three characteristic temperatures obtained from the dynamic DSC test, the theoretical curing temperature of this adhesive film was calculated to be 182 ℃, and it took about 100 min to realize 100% curing at this temperature, which was verified by DSC test. ⑶ The reaction process of the above high temperature curing was verified by FT-IR comparison, and the epoxy group was basically reacted completely after treatment at 200 ℃, which was consistent with the results of the above analysis.

Keywords】modified acrylate; adhesive; curing; performance; flexible printed circuit board


Preparation and reliability study of single-component addition-type thermal conductive silica gel

Xu Yuwen, Liu Liangjun, Yang Haibing, Xie Xiang

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

【AbstractTwo kinds of single-component addition-type thermal conductive silica gel (UB-5705 and UB-5707) were prepared by using low to medium viscosity vinyl silicone oil, hydrogen containing silicone oil combined with micron alumina thermal conductive powder as raw materials. The obtained products were clarified by infrared spectrometer analysis, and further characterized by differential scanning calorimeter, thermogravimetric analyzer and thermal conductivity tester. High temperature and high humidity, hot and cold cycling, and high temperature aging reliability studies were also carried out. The research results showed that, ⑴The synthesis of thermal conductive silica gel was effective and met the test expectations. The thermal cracking temperature (Td) was greater than 250 ℃, the thermal conductivity coefficient was greater than 1.90 W/(m·K), the thermal resistance was lower than 10.184 ℃·cm2/W, and the shear strength was more than 5.00 MPa. ⑵In contrast, UB-5705 had superior toughness, while UB-5707 had a higher thermal conductivity. ⑶After 1 000 h of high temperature and high humidity, cold and hot cycling and high temperature aging, respectively, two kinds of thermal conductive silica gel still maintained high thermal conductivity and mechanical properties, with thermal conductivity > 1.80 W/(m·K), shear/tensile strength > 4.0 MPa, the elongation at break > 20%. The comprehensive performance met the requirements for reliability of chip and radiator assembly.

【Keywordssingle-component; silica gel; addition-type; high thermal conductivity


Effect of H-MMT on properties of low molar ratio urea-formaldehyde resin adhesive

Zhao Yahong1, Yu Xiaofang2

(1. Chifeng Industrial Vocational Technical College, Chifeng  024005, Inner Mongolia, China; 2. College of Materials Science and Art Design, Inner Mongolia Agricultural University, Hohhot  010018, Inner Mongolia, China)

【AbstractAcidified montmorillonite (H-MMT) was prepared by acidified treatment of montmorillonite. Then, the prepared H-MMT was added into the low molar ratio urea-formaldehyde resin synthesis system to obtain the urea-formaldehyde resin adhesive modified by H-MMT. The effects of H-MMT addition on the viscosity, solid content, free formaldehyde content and bonding properties of urea-formaldehyde resin adhesive were investigated by controlling the feeding ratio and release time. At the same time, the differences between unmodified urea-formaldehyde resin adhesive and those modified by H-MMT were compared and analyzed. The research results showed that in the second stage of the reaction in the urea-formaldehyde resin synthesis system, 3% H-MMT was added, and the performance of the modified urea-formaldehyde resin adhesive was the best. The free formaldehyde content of the adhesive was measured to be 0.17%, the curing time was 57.5 seconds, and the bonding strength was 1.1 MPa. The modified urea-formaldehyde resin adhesive with the addition of H-MMT contained a large number of ether bonds and hydroxymethyl groups, which could improve the bonding performance of the adhesive. The presence of unreacted residual urea in the H-MMT modified urea-formaldehyde resin adhesive further reduced the free formaldehyde content of the system.

【Keywordsmontmorillonite; urea-formaldehyde resin; adhesive; property; structure


Development and Application

Preparation and application research of improved water-resistant cellulose nanofibers adhesive

Yin Shengmei

(Guangzhou Vocational University of Science and Technology, Guangzhou  510550, Guangdong, China)

【AbstractCellulose nanofibers (CNF), as a kind of biomass material, contain a large number of hydroxyl groups on their surface, which naturally have the ability to bond to polar surfaces. However, CNF containing only hydroxyl groups has low bonding strength and is not easy to bond with water molecules, which affects cohesion and adhesion. In response to this situation, in this study, based on the characteristics of chemical bonding between polyethyleneimine (PEI) and tannic acid (TA) in a very short time and the ability to form chain entanglement, tannic acid was added to the surface of CNF, CNF-TA-PEI adhesive was prepared through physical blending method, and the stability and water resistance of the adhesive were investigated. The research results showed that when m(TA) : m(PEI)=60:40, although CNF-TA-PEI adhesive was soaked in water for 14 days, the measured bonding strength still reached (140.7±7.3) kPa. After soaking for more than 21 days, its bonding performance showed a continuous downward trend, and the measured strength value was (61.9±1.4) kPa at 28 days. The above results indicated that CNF-TA-PEI adhesive had good interface adhesion and water resistance, and had certain application prospects in practice.

【Keywordscellulose nanofibers; adhesive; tannic acid; polyethyleneimine


Study on polyisocyanate crosslinked polyvinyl alcohol wood adhesive

Pan Chan, Long Yifei, Zhao Junli, Guo Xiaoqin

(Wuhan City College, Wuhan  430075, Hubei, China)

【AbstractThe orthogonal experimental method (controlling five levels and six factors) was used to investigate the effect of the addition amount of nonionic surfactant OP-10, catalyst stannous octanoate, crosslinking agent JQ-4, the reaction time, the reaction temperature and the mass of relative volume of polyvinyl alcohol on the shear strength of modified polyvinyl alcohol wood adhesive by using polyvinyl alcohol solution as the matrix. The research results showed that, ⑴ All six factors selected in the orthogonal experiment had an effect on the shear strength of the adhesive, with the mass of relative volume of polyvinyl alcohol solution having the greatest effect. According to the range analysis, the order of factors affecting the adhesive curing was as follows: Mass of relative volume of PVA solution > OP-10 addition > JQ-4 addition > stannous octanoate addition > reaction time > reaction temperature. ⑵ The adhesive sample generally showed a homogeneous milky white color, and the color stability of all samples was good. The adhesive had good stability, was not easy to deteriorate, freeze-resistant, easy to store, and the fluidity was generally superior. ⑶ The relative optimal synthesis conditions for the adhesive sample were: PVA addition of 8 g/100 mL, OP-10 addition of 0.1 mL/100 mL, JQ-4 addition of 0.3 mL/100 mL, catalyst addition of 0.3 mL/100 mL, reaction time of 75 minutes, and reaction temperature of 60 ℃. The prepared emulsion was stable milky white with excellent performance. It could be used as adhesive in the construction industry and was more environmentally friendly.

【Keywordspolyisocyanate; polyvinyl alcohol; wood adhesive


The influence of adding SIS with high styrene content on the performance of

hot melt pressure sensitive adhesive

Zhu Jinzhu1, Cao Xiusheng1, Mao Hong1, Zhou Jiandong2

[1.TSRC (Nantong) Industries Ltd., Nantong  226017, Jiangsu, China; 2.TSRC-UBE (Nantong) Chemical Industrial Co., Ltd., Nantong  226017, Jiangsu, China]

【AbstractUsing TSRC SIS 4113 as the main body of hot block copolymer of SIS-based hot melt pressure sensitive adhesive, two kinds of SIS 4211 and 4411 with high styrene content were blended, and SIS type hot melt pressure sensitive adhesive was prepared by melt mixing method. The influence of different contents of SIS with high styrene on the basic properties, adhesion properties, and rheological properties of hot melt pressure sensitive adhesive was investigated. The research results showed that, ⑴ With the increase of the ratio of 4211 and 4411, the viscosity of hot melt pressure sensitive adhesive decreased and the softening point increased, while the effect of mixing 4411 changed significantly, the adhesion performance, high-temperature holding power, and shear failure temperature were all significantly improved. ⑵ The loop tack and 180° peel force after blending 4211 had slight fluctuations, the addition of 4411 had a significant impact on the wetting performance, with a significant decrease in the loop tack and 180° peel force. ⑶ The rheological curves showed that as the blending ratio increased, the glass transition temperature (Tg) point and flow point gradually increased, and the storage modulus significantly increased, corresponding to the results of the high-temperature holding power test.

【KeywordsSIS with high styrene content; hot melt pressure sensitive adhesive; adhesion performance; rheological performance


Special Topics and Review

Development and discussion of high-content rubberized asphalt technology

Wang Hanbing, Wang Shifeng

(School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai    200240, China)

【AbstractHigh-content rubberized asphalt, as new technology for road construction, has the advantages such as excellent low-temperature performance, good durability, high rubber powder consumption and high environmental benefits. In order to further promote the application of high-content rubberized asphalt technology, clarify its development status and demands, in this article, the technical features, colloidal structure, performance evaluation, mainstream processes, engineering application and problems of high-content rubberized asphalt were reviewed. Firstly, the concept of high-content rubberized asphalt was clarified, and its modification mechanism different from traditional rubber asphalt was explained. Secondly, based on the occurrence of chemical reactions, the existing physical and chemical methods were compared and analyzed. And the modification process of high-content rubberized asphalt was further explored through the change of colloidal structure, the structural performance was analyzed in combination with its performance. Furthermore, an in-depth exposition was conducted on two chemical methods of desulfurization with rubber powder and boiling in asphalt, summarizing and evaluating the current mainstream high-content rubberized asphalt preparation technologies. Finally, the feasibility and superiority of high-content rubberized asphalt were discussed through engineering cases, and the existing engineering problems were pointed out.

【Keywordsroad engineering; rubberized asphalt; review; high-content; devulcanized rubber powder; colloidal structure


Research progress on the application of epoxy acrylate in anaerobic adhesive

Wang Xinli1,2,Wang Yang1,2, Ma Chuang1,2, Song Jinming1,2, Feng Zenghui1,2, Tao Jiafa1,2, Liu Xiusheng1,2

(1.State Key Laboratory of Special Surface Protection Materials and Application Technology, Wuhan Research Institute of Materials Protection, China Academy of Machinery Science and Technology, Wuhan  430030, Hubei, China; 2.China Academy of Machinery Science and Technology Group, Beijing  100080, China)

【AbstractIn this paper, the composition of anaerobic adhesive was firstly introduced, taking the initiation system of hydrogen peroxide isopropylbenzene-dimethyl-p-toluidine-saccharin as an example, the initiation and curing mechanism of this initiation system was briefly introduced. Secondly, the synthesis of epoxy acrylate and its related catalytic mechanism were described. The application of epoxy acrylate in anaerobic adhesive was further reviewed, and the advantages of epoxy acrylate in improving the strength and heat resistance of anaerobic adhesive were analyzed. Meanwhile, the effects of different torque regulators on the performance and the application study of modified epoxy acrylate in anaerobic adhesive were discussed. Finally, suggestions were put forward on how to better utilize epoxy acrylate to improve the performance of anaerobic adhesive.

【Keywordsanaerobic adhesive; epoxy acrylate; curing mechanism