Scientific Research Report

Structure and properties of urea-starch-glyoxal resin reinforced by epoxy resin

Xie Yikun, Wang Delong, Wang Jinwen, Dong Chunlei, Sun Hao, Du Guanben, Deng Shuduan

(Yunnan Key Laboratory of Wood Adhesives and Glue Products, Southwest Forestry University, Kunming  650224, Yunnan, China)

【Abstract】In order to improve the properties of urea-starch-glyoxal (USG) wood adhesive, epoxy resin-modified USG resin was prepared by using glyoxal, urea, oxidized cassava starch and epoxy resins with different mass fractions. The solid content, viscosity and thermal properties were tested, and three-layer poplar plywood was prepared with it, the corresponding properties were measured, and finally its structural characteristics were characterized. The research results showed that the addition of epoxy resin could increase the solid content of USG resin, but it had little effect on the viscosity of USG resin. Differential scanning calorimetry (DSC) test showed that the curing temperature of USG resin could be reduced by adding epoxy resin. When the addition amount of epoxy resin was 2%, the viscosity of the resin reached 593.4 mPa∙s, the solid content was 54.1%, and the dry shear strength, cold water wet strength and hot water wet strength of the prepared plywood were 2.11, 1.60 and 0.66 MPa, respectively. Infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance spectroscopy (¹³C-NMR) tests showed that there occurred a chemical reaction between the epoxy group of epoxy resin and the long chain of USG resin.

【Keywords】urea-starch-glyoxal resin; epoxy resin; wood adhesive; structure and property

Preparation and properties of solvent-free polyurethane joint-sealing material for hydraulic engineering

Li Cuiling^1,2,3, Jiang Dongyang^1,2,3, Jiang Xuexing^1,3, Du Ming^1,3

(1.Henan Provincial Water Conservancy Research Institute, Zhengzhou  450003, Henan, China; 2.Henan Keda Water Conservancy Survey and Design Co., Ltd., Zhengzhou  450003, Henan, China; 3.Key Laboratory of Hydraulic Engineering Safety Technology of Henan, Zhengzhou  450003, Henan, China)

【Abstract】A kind of solvent-free polyurethane joint-sealing material for hydraulic engineering was prepared with polyether polyol and isocyanate, and the effects of different raw material ratios on the mechanical properties of component A and joint-sealing material were studied. The research results showed that in the solid fillers, when the addition amount of silica was 1.8%-2.2% (relative to the total mass of components A and B, the following was the same), the addition amount of calcium carbonate was 18.5%-22.2%, and the addition amount of pulverized fuel ash was 16.3%-19.3%, the comprehensive performance of joint-sealing material was relatively excellent. In the liquid fillers, when the addition amount of petroleum resin was between 4% to 6%, and the addition amount of plasticizer was between 3% to 4%, the comprehensive performance of joint-sealing material was relatively excellent. The tensile strength of the prepared two-component polyurethane joint-sealing material for hydraulic engineering was not less than 2.0 MPa, the elongation at break was not less than 600%, and the elastic recovery rate was not less than 80%, which could meet the needs of the expansion joint-sealing technology of hydraulic engineering.

【Keywords】polyurethane; deformation joint; joint-sealing material; solvent-free; anti-seepage

Study on reliability of hot melt pressure sensitive adhesive material for lithium battery

Gao Jie¹, Tang Fangcheng¹, Wang Jiasheng¹, Du Zhuang¹, Wu Lixia¹, Shen Yongbin¹, Sun Guoxing², Lyu Dong³

(1.Guangzhou Lushan New Materials Co., Ltd., Guangzhou    510530, Guangdong, China; 2.University of Macau, Macau    999078, China; 3.Guangzhou HKUST Fok Ying Tung Research Institute, Guangzhou    511458, Guangdong, China)

【Abstract】Hot melt pressure sensitive adhesive material for lithium battery was prepared with styrene block copolymer (SBC) and tackifying resin as the main raw materials, and adding maleic anhydride grafted polyolefin (PO-g-MAH) and solid wax. The effects of SBC type on creep resistance, bonding property and aging resistance, the effects of tackifying resin type and content on peel strength and electrolyte resistance reliability, the effects of PO-g-MAH modification on peel strength and water resistance reliability, and the effects of solid wax on processing performance and aging reliability were all investigated. The research results showed that the combination mode of MAH-g-SEBS and SIS was selected as the SBC type, which could make the peel strength reach 15.2 N•(8 mm)^-1 and the holding power reach 29 h at 60 ℃. Hydrogenated petroleum resin or terpene resin could be selected as tackifying resin, and the mass ratio should be controlled within 45%-55%. PO-g-MAH modification could increase the peel strength by 16.0%, and the decrease rate of peel strength after soaking in water was reduced from 27.0% to 8.2%. PA wax could effectively solve the problem of poor processability and wire drawing, so that the material had good resistance to high temperature and high humidity aging, and had a wide range of temperature for application.

【Keywords】lithium battery; hot melt pressure sensitive adhesive material; peel strength; aging resistance

Study on chemical composition of nonmetallic residue in conductive slip ring based on nano infrared technology

Wang Mengyin, Tian Yazhou, Ye Zhuang, Wu Guangdong, Ding Ying, Wang Xiuli, Li Li, Liu Lanying

（Beijing Institute of Control Engineering, Beijing  100190, China）

【Abstract】The contact resistance of a conductive slip ring product increased abnormally during the test, and there were abnormal black debris on its surface observed by microscope. In order to deeply analyze the chemical composition of black wear debris and reveal its contamination source, the chemical composition of black wear debris was studied by using nano infrared technology (AFM-IR), and the application of AFM-IR technology in the analysis of chemical composition of nonmetallic residue of aerospace product was discussed. The research results showed that the chemical composition of black debris could be analyzed in-situ by using AFM-IR technology, which broke through the diffraction limit of traditional infrared spectroscopy technology and obtained nano infrared spectroscopy. The most possible source of contamination was determined from an insulating tape, and the contamination recurrence test was used to make the problem reappear. Furthermore, the cleaning test was used to improve the production process, which avoided the problem of organic contamination and improved the quality of conductive slip ring product.

【Keywords】nano infrared technology (AFM-IR); conductive slip ring; contact resistance; contamination detection; cleaning

Development and Application

Research on microspace filling process of thermal insulation adhesive at bottom of BGA

Zhang Sheng, Zhang Chenhui, Liu Zhidan, Jin Xing

(Xi’an Research Institute of Navigation Technology, Xi′an  710068, Shaanxi, China)

【Abstract】By analyzing the intrinsic properties of thermal insulation adhesive, composition formula, the actual spatial position relationship of printed circuit board assembly and the characteristics of main ball grid array (BGA) device packing structure, the process test pieces were designed and manufactured, the theoretical research on the filling model of thermal insulation adhesive was carried out, and the effects of viscosity, preheating temperature, filling mode and vacuum degree on the filling effect were explored. After a series of process test and research on thermal insulation adhesive filling and the design optimization of filling cofferdam tooling, the optimized process parameters, filling mode and process flow affecting the filling were obtained. The prepared verification sample was tested by computed tomography (CT) scan, and the filling void rate was less than 10%. The visualization filling process verification was realized by adopting the glass-based BGA process device, and the process method was simple, reasonable and feasible.

【Keywords】thermal insulation adhesive; BGA device; cofferdam tooling; bottom filling; void rate; visualization

Preparation and properties of cationic waterborne polyurethane coating

Kuang Guankun¹, Liu Yan¹, Xu Lili¹, Zhou Yuanyuan¹, Qin Ying¹, Xue Meng¹, Xin Binjie²

(1.School of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai  201620, China; 2.School of Textiles and Fashion, Shanghai University of Engineering Science, Shanghai  201620, China)

【Abstract】Cationic waterborne polyurethane (CWPU) coating applied to tinplate was synthesized by using polycaprolactone diol (PCL), isophorone diisocyanate (IPDI), diethylene glycol (DEG), 2-hydroxyethyl acrylate (HEA) and N-methyl diethanolamine (MDEA) as main raw materials. The effects of different isocyanate index (R value) and the mass ratio of MDEA to PCL on the properties of CWPU coating were investigated. The CWPU coating was characterized by thermogravimetric analysis (TG), water absorption, differential scanning calorimetry (DSC), hardness and water resistance, and the effects of the ratio of soft and hard segments and the content of hydrophilic groups on the coating properties were explored. The research results showed that when the mass ratio of MDEA to PCL was constant and the R value was 1.8, the water absorption of CWPU coating was the lowest and the comprehensive performance was relatively good. Fixing the R value to 1.8, with the increase of the mass ratio of MDEA to PCL, the storage stability of CWPU emulsion was generally good, the hardness of CWPU coating increased gradually, the water resistance and thermal decomposition temperature both showed a trend of increasing first and then decreasing, and the particle size showed a trend of first decreasing and then increasing. When the R value was 1.8 and n(MDEA):n(PCL) was 3.47∶1, the comprehensive performance of CWPU coating was excellent.

【Keywords】cationic waterborne polyurethane; R value; n(MDEA)∶n(PCL) ratio; tinplate coating; performance characterization

Study on influence of hollow glass bead on properties of silane-modified polyether sealant

Cai Yaowu, Li Yao, Lu Yuchong, Wang Jianbin, Tao Xinliang

（Zhengzhou Hollowlite Materials Co., Ltd., Zhengzhou  450001, Henan, China）

【Abstract】Using silane-modified polyether resin (MS) as the main raw material, and reacting with plasticizer, hollow glass bead, reinforcing filler, dehydrating agent, coupling agent and catalyst, a kind of MS sealant used in the field of prefabricated building was prepared. The influence of the adding method and amount of hollow glass bead on the density, extrudability and thermal conductivity of MS sealant was emphatically discussed, and the mechanical properties of the sealant were also investigated. The research results showed that keeping the basic formula unchanged, when adding hollow glass bead, the extrudability was significantly increased, and the MS sealant performance was relatively excellent when the adding amount was 10-15 phr. Keeping the other substances unchanged in the basic formula, when using hollow glass bead to replace heavy calcium carbonate, the MS sealant performance was relatively excellent with the using amount of 8-20 phr.

【Keywords】MS sealant; hollow glass bead; density; extrudability; thermal conductivity

Study on waterproof performance of adhesive bonding layer on building surface

Lin Yonghua^1,2

(1.Qingjian Group Co., Ltd., Qingdao  266000, Shandong, China; 2.Qingjian Overseas Development Co., Ltd., Qingdao  266000, Shandong, China)

【Abstract】Three types of patch samples, i.e. A, B and C were selected and coated with 1-2 layers of fluorine-containing waterborne polyurethane acrylate adhesive (WPUA), vinyl acetate-butyl acrylate-acrylamide (VAc-BA-AM) ternary copolymerized emulsion adhesive and cement, respectively. Based on the results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the water absorption, water resistance, water permeability, shearing properties and interface pull-out properties were investigated. The research results showed that the water absorption rate of the sample coated with WPUA adhesive was significantly lower than that of the sample coated with cement, and after immersion in water for 20 days, the water absorption rate of the A and B patch coated with double-layer WPUA was only 5.8% and 5.1% of the control group. Under the water pressure of 0.1-0.3 MPa, the sample coated with double-layer WPUA had no water seepage and the stress was not weakened within 1 h, while the sample coated with double-layer VAc-BA-AM ternary copolymerized emulsion adhesive and cement had different degrees of water seepage and stress reduction. The sensitivity of tensile properties and shear properties of the sample coated with three waterproof adhesive materials to high temperature was in the following order: WPUA>VAc-BA-AM ternary copolymerized emulsion adhesive>cement. The waterproof performance of WPUA adhesive was better than that of other two waterproof bonding materials in water absorption and water resistance test, shear test, pull-out test and water seepage test. Therefore, WPUA adhesive could be used as the waterproof bonding material for building surface bonding.

【Keywords】building surface patch; WPUA adhesive; bonding layer; waterproof performance

Special Topics and Review

Research progress of graphene/polymer flexible transparent conductive film

Qi Kailiang¹, Zhang Fan², Pang Zhangang³

(1.School of Electrical Engineering, Shaanxi Polytechnic Institute, Xianyang  712000, Shaanxi, China; 2. School of Materials Science & Engineering, East China Jiaotong University, Nanchang  330013, Jiangxi, China; 3. Shaanxi Helicopter Co., Ltd., Xi’an  710000, Shaanxi, China )

【Abstract】Flexible transparent conductive film (FTCF) is a very important material in the optoelectronic industry chain, and is also a breakthrough of flexible display technology. Graphene is a two-dimensional material with small sheet thickness and high theoretical conductivity, which can match the flexibility of resin material to a certain extent, and therefore, graphene/polymer FTCF has become a research hotspot in the field of optoelectronic material. In this paper, the research progress of graphene/polymer FTCF in recent years was reviewed, and its key characteristic, preparation method and important application were emphasized. Finally, the related researches were summarized and prospected. It could be predicted that with the maturity of graphene industry and the increasing demand for flexible display device, graphene/polymer FTCF would play a more important role in various fields.

【Keywords】flexible transparent conductive film; graphene; polymer; key characteristic; application

Research progress on crystal structure and its amorphous transformation of urea-formaldehyde resin adhesive

Xiang Yang, Tong Yingfang, Chen Taian, Liu Junwei, Guo Yunhui, Liu Yaqing

(Key Laboratory of Functional Nanocomposites of Shanxi Province, College of Materials Science and Engineering, North University of China, Taiyuan  030051, Shanxi, China)

【Abstract】Urea-formaldehyde resin is the most used and widely used adhesive in wood industry. However, formaldehyde volatilization in urea-formaldehyde resin will cause great harm to people’s living environment. A simple and effective method to reduce formaldehyde emission is to synthesize urea-formaldehyde resin with low formaldehyde/urea mass ratio. However, the low mass ratio of urea-formaldehyde resin will form strong hydrogen bonds between linear molecules during the curing state, thus a large number of crystallization zones are formed, which further deteriorates the bonding property of the resin. In this paper, the research progress in recent years on the transformation of crystalline urea-formaldehyde resin into amorphous polymer by blocking hydrogen bonds were introduced, and the purpose of improving the bonding property of the resin and reducing formaldehyde volatilization was achieved.

【Keywords】urea-formaldehyde resin; crystal; amorphous; adhesive; modification

Research progress of high temperature resistant polyimide adhesive at home and abroad

Xie Longquan, Yu Xinhai, Xia Yu

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

【Abstract】The research and application progress of high temperature resistant polyimide (PI) adhesive in recent years were reviewed. The structural characteristics, classification, modification, and functional development of PI adhesive were summarized. The structural modification of PI adhesive such as introducing flexible groups into the PI main chain, adding monomer copolymerization into the system, as well as the research progress of organic/inorganic modified PI adhesive with epoxy resin, polyurethane, carbon nanotube, and epoxy resin were emphatically introduced. Finally, the application prospect of high performance PI adhesive in industry was prospected.

【Keywords】high temperature resistance; polyimide; adhesive