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Straight chain structure of the paint crosslinking agent
2017-7-11 19:48:55
Straight chain structure of the paint crosslinking agent
Physical and chemical properties: light yellow transparent liquid, slightly soluble in water, soluble in alcohols, ethers, ketones and other polar organic solvents, and polyether, polyester polyol compatibility.
Density 1.022
Viscosity (20 ℃) ??mPa·ss290±10
Pour Point ℃-9
Boiling point of310°C
The activation energy Ea d [ln (B / T2p)] d (1 / Tp) of the resin / crosslinker system was calculated by Kissinger method [Equation (1)] = - Ea
R (1) According to equation (1), 1 / Tp is plotted with -ln (B / T2 p), and the slope of -Aa / R is linearly fitted to obtain the activation energy Ea.
The activation energy of crosslinking reaction is the lowest in A / IPDA system, indicating that the reactivity is the largest and the A / DMDC system is centered. The activation energy of A / D-230 system is the largest and the reactivity is the smallest.
This is because the linear structure of the cross-linking agent D-230 due to its linear structure of the regular, there is a relatively obvious hydrogen bond, the linear structure makes the functional group stability, low activity. The cyclic structure of the crosslinking agent IPDA, DMDC regularity is relatively poor, hydrogen bond effect is not obvious, so the functional group activity is relatively large.
Due to the thermal hysteresis, the peak temperature of the exothermic peak increases with the increase of the DSC heating rate, and the epoxy resin / crosslinker is often crosslinked at constant temperature or stage temperature, and the heating rate is 0 The The T-B diagram can be used to extrapolate the isothermal crosslinking temperature of the crosslinked system to determine the optimal cross-linking procedure for the resin. The relationship between To, Tp and Ti of three different resin / crosslinker systems. Each line extrapolated to B = 0 to obtain the isothermal crosslinking temperature of the crosslinking system.
The A / D-230 and A / DMDC systems have the lowest cross-linking temperature and the relatively low activity of the A / D-230 and A / DMDC systems. -230 system requires a higher temperature is due to the ring structure of the DMDC molecular chain segmentation effect is more obvious.
Chinese name: Diethyl toluene diamine(DETDA)Physical and chemical properties: light yellow transparent liquid, slightly soluble in water, soluble in alcohols, ethers, ketones and other polar organic solvents, and polyether, polyester polyol compatibility.
Density 1.022
Viscosity (20 ℃) ??mPa·ss290±10
Pour Point ℃-9
Boiling point of310°C
Flash Point°C161.1°C
Analysis of Cross - Link Reaction Degree. Effect of Reaction Time on Viscosity of Resin / Crosslinker Mixture. Resin and cross-linking agent in accordance with the proportion of 25e after mixing, with the resin and the reaction of cross-linking agent, molecular weight increases, the formation of branched structure and three-dimensional network structure, viscosity will gradually increase with the degree of reaction and gradually increased, 3 The viscosity of the resin / crosslinker system varies with the reaction time.
The A / IPDC system increases rapidly from the initial viscosity to 2000 mPa # s in 2 h, and the activity is the lowest Of the A / D-230 system in the test time range of viscosity change is not obvious.
Effect of Crosslinking Temperature on Gel Time of System. Analyze the gel time of the mixture by means of a flat knife method. Weigh 6 g of the mixed resin and the cross-linking agent into the circular groove of the heating plate and feed the teeth with a toothpick until the elongated filaments can be pulled out. The A / D-230 reactivity was the lowest, the response was slow, the A / DMDC was the highest, the A / IPDA activity was the highest and the reaction was the fastest. This is consistent with the analysis data of the previous activation energy.
Infrared tracking test. With the progress of the crosslinking reaction, the number of epoxy functional groups in the resin / crosslinker system gradually decreased, and the epoxy index was calculated by comparing the change of the peak area of ??the epoxy group of the resin system before and after crosslinking. System of cross-linking reaction.
Infrared spectra of 3 resin / crosslinker systems after crosslinking at 80e for 6 h. It can be seen that the absorption peak area of ??the epoxy groups at 915 cm-1 in the cross-linked curves b, c and d is significantly reduced compared to the uncrosslinked epoxy resin, indicating that the crosslinked epoxy groups Has been greatly reduced.
The FTIR spectra of the three resin crosslinker systems before and after cross-linking were the relationship between the epoxy index and the crosslinking time of the three resin / crosslinker systems at 80e. It can be seen that the crosslinking time Extended, cross-linked epoxy index decreased to 6h after the epoxy index to reduce the trend is slow.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
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