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Composite Crosslinking Agent for Coatings
2017-7-15 12:11:43
Composite Crosslinking Agent for Coatings
The effect of crosslinking system on the crosslinking reaction of 3221 epoxy resin was studied by DSC method, and the reaction mechanism of composite crosslinking agent was discussed.
Compared with the use of dicyandiamide alone, the substituted urea decomposes at a relatively low temperature, and the decomposition product catalyzes or activates the epoxy resin crosslinking reaction, which is why the accelerator reduces the crosslinking temperature of the system.
The use of a composite crosslinker reduces the temperature of the entire crosslinking process, where the Tp drops by 56 ° C. Practical experience shows that the maximum cross-linking temperature can be reduced by 40 ℃ ~ 50 ℃; but the resin system at room temperature is also shortened, but still can reach 1 to 2 months.
The cross - linking dynamics of the system. The reactivity of the epoxy resin crosslinker system is related to both epoxy and crosslinking agents. Crosslinking kinetics research is the basis of system cross-linking process model research. The dynamic DSC method is the most commonly used method for studying the crosslinking kinetics of resin.
The crosslinker was added to 3221 resin and ground uniformly with colloid mill. DSC was measured at different heating rates. The characteristic data of the spectrum were shown in Fig. The linear regression of -ln (ΒT2 p) ~ 1Tp for systems 1 and 2 yields a linear slope of 17.06 × 103 for system 1 and a slope of 10.13 × 103 for system 2 lines.
According to the Kissinger equation, the Ea of the 3221 epoxy resin was calculated to be 142 kJ / mol by using the curing system 1, that is, dicyandiamide. The crosslinked Ea was 84.2 kJ / mol using the crosslinking system 2, The activation energy of the two crosslinking systems is 58 kJ / mol.
The activation energy is a measure of the energy required for the reaction of the crosslinking system. The larger the value is, the more energy is required for the crosslinking reaction, and the higher the crosslinking temperature. The difference in activation energy indicates that the addition of substituted urea reduces the activation energy of the crosslinking reaction of the epoxy resin, thus reducing the reaction temperature and further confirming that the substituted urea does promote the 3221 system of dicyandiamide crosslinking.
Chinese name: Diethyl toluene diamine(DETDA)
The effect of crosslinking system on the crosslinking reaction of 3221 epoxy resin was studied by DSC method, and the reaction mechanism of composite crosslinking agent was discussed.
Compared with the use of dicyandiamide alone, the substituted urea decomposes at a relatively low temperature, and the decomposition product catalyzes or activates the epoxy resin crosslinking reaction, which is why the accelerator reduces the crosslinking temperature of the system.
The use of a composite crosslinker reduces the temperature of the entire crosslinking process, where the Tp drops by 56 ° C. Practical experience shows that the maximum cross-linking temperature can be reduced by 40 ℃ ~ 50 ℃; but the resin system at room temperature is also shortened, but still can reach 1 to 2 months.
The cross - linking dynamics of the system. The reactivity of the epoxy resin crosslinker system is related to both epoxy and crosslinking agents. Crosslinking kinetics research is the basis of system cross-linking process model research. The dynamic DSC method is the most commonly used method for studying the crosslinking kinetics of resin.
The crosslinker was added to 3221 resin and ground uniformly with colloid mill. DSC was measured at different heating rates. The characteristic data of the spectrum were shown in Fig. The linear regression of -ln (ΒT2 p) ~ 1Tp for systems 1 and 2 yields a linear slope of 17.06 × 103 for system 1 and a slope of 10.13 × 103 for system 2 lines.
According to the Kissinger equation, the Ea of the 3221 epoxy resin was calculated to be 142 kJ / mol by using the curing system 1, that is, dicyandiamide. The crosslinked Ea was 84.2 kJ / mol using the crosslinking system 2, The activation energy of the two crosslinking systems is 58 kJ / mol.
The activation energy is a measure of the energy required for the reaction of the crosslinking system. The larger the value is, the more energy is required for the crosslinking reaction, and the higher the crosslinking temperature. The difference in activation energy indicates that the addition of substituted urea reduces the activation energy of the crosslinking reaction of the epoxy resin, thus reducing the reaction temperature and further confirming that the substituted urea does promote the 3221 system of dicyandiamide crosslinking.
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine packing： net weight 200KG/ galvanized iron drum (a small cabinet pallet loaded 16 tons), 1000KG/IB barrels (a small cabinet loaded 18 tons or 23 tons of ISOTANK).
Prediction of cross - linking process parameters. It is found that the three characteristic temperatures T (features) of the DSC curve vary with the heating rate B, and increase with increasing B. The reason for this can be explained by the fact that the time of absorption of the system is relatively short, the energy absorbed from the outside is less, that is, the response lag is more, so T (characteristic) will be improved accordingly.
This is the reason why the heating rate and the T (characteristic) are almost linearly changed when the crosslinking temperature of a thermosetting material is measured, and thus the actual crosslinking temperature and the test value of the resin are difficult to be unified.
In this paper, different cross-linking temperature is obtained by different temperature rise rate beta test, then T ~ B diagram extrapolation method is used to obtain the parameter value of the cross-linking process temperature, and then the best value is found from the practical application The The characteristic temperatures Ti, Tp and Tf in Tab.2 are plotted against the B, and linear regression is used to extrapolate the three straight lines of Fig.1 to the three-point temperature at which B is equal to zero as the characteristic temperature of the crosslinking process. Is defined as the gel temperature Tgel, 100 ° C; the crosslinking temperature Tcure is 128 ° C; the post-treatment temperature Ttreat is 197 ° C. The method of predicting the parameters of the process has certain guiding effect on determining the optimum crosslinking process.
Cross - linking process parameter verification. Crosslinking degree is an important parameter for thermosetting materials and can be conveniently measured by DSC. The crosslinking reaction of the epoxy resin is an exothermic reaction, and the amount of exothermic heat is related to the type of resin function, the number of functional groups participating in the reaction, the type and amount of the crosslinking agent.
For a given resin system, the cross-linking reaction heat per unit mass is constant, and the cross-linking degree α can be calculated using the following formula: α = (H0-? HR)? H0 (2) where: The total heat released from the resin system when fully crosslinked, HR - the resin that has not been crosslinked continues to complete the residual heat at the time of crosslinking, and its value can be obtained from the exothermic peak area of ??the DSC curve.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Prediction of cross - linking process parameters. It is found that the three characteristic temperatures T (features) of the DSC curve vary with the heating rate B, and increase with increasing B. The reason for this can be explained by the fact that the time of absorption of the system is relatively short, the energy absorbed from the outside is less, that is, the response lag is more, so T (characteristic) will be improved accordingly.
This is the reason why the heating rate and the T (characteristic) are almost linearly changed when the crosslinking temperature of a thermosetting material is measured, and thus the actual crosslinking temperature and the test value of the resin are difficult to be unified.
In this paper, different cross-linking temperature is obtained by different temperature rise rate beta test, then T ~ B diagram extrapolation method is used to obtain the parameter value of the cross-linking process temperature, and then the best value is found from the practical application The The characteristic temperatures Ti, Tp and Tf in Tab.2 are plotted against the B, and linear regression is used to extrapolate the three straight lines of Fig.1 to the three-point temperature at which B is equal to zero as the characteristic temperature of the crosslinking process. Is defined as the gel temperature Tgel, 100 ° C; the crosslinking temperature Tcure is 128 ° C; the post-treatment temperature Ttreat is 197 ° C. The method of predicting the parameters of the process has certain guiding effect on determining the optimum crosslinking process.
Cross - linking process parameter verification. Crosslinking degree is an important parameter for thermosetting materials and can be conveniently measured by DSC. The crosslinking reaction of the epoxy resin is an exothermic reaction, and the amount of exothermic heat is related to the type of resin function, the number of functional groups participating in the reaction, the type and amount of the crosslinking agent.
For a given resin system, the cross-linking reaction heat per unit mass is constant, and the cross-linking degree α can be calculated using the following formula: α = (H0-? HR)? H0 (2) where: The total heat released from the resin system when fully crosslinked, HR - the resin that has not been crosslinked continues to complete the residual heat at the time of crosslinking, and its value can be obtained from the exothermic peak area of ??the DSC curve.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
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