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Dicyandiamide and substituted urea coatings
2017-7-15 12:11:30
Dicyandiamide and substituted urea coatings
In this paper, the reaction kinetics of dicyandiamide and dicyandiamide + substituted urea cross-linking agent was analyzed, and the cross-linking process parameters of dicyandiamide + substituted urea cross-linking agent were predicted.
The cross-linking system with dicyandiamide + substituted urea cross-linking agent can reduce the apparent activation energy Ea of 3221 system by 58 kJmol compared with dicyandiamide alone, and the former crosslinking temperature is about 50 ℃ lower than that of the latter Ease.
Different epoxy resin system for the use of different cross-linking agent can have different cross-linking temperature, the general cross-linking temperature higher than 150 ℃ called high temperature crosslinking resin, crosslinking temperature of 90 ℃ ~ 150 ℃ called For the temperature cross-linked resin. At present, the use of lower crosslinking temperature to obtain a resin system with a higher glass transition temperature (Tg) is a thermal study of epoxy resin.
The main problem is to select the appropriate cross-linking agent and accelerator to achieve the purpose of reducing the cross-linking temperature, for example, the use of latent crosslinking agent or accelerator can reduce the cross-linking temperature while ensuring that the resin has a high heat-resistant temperature And longer shelf life.
The epoxy resin system investigated in this paper is a crosslinked epoxy resin substrate 3221 at a medium temperature (125 ° C to 130 ° C). The system is completely cross-linked after the Tg of 170 ℃, the cross-linking agent for the composite cross-linked system dicyandiamide + substituted urea.
In this paper, the effects of different crosslinking systems on the crosslinking reaction of the epoxy resin system were reported. The reaction mechanism was also discussed. The reaction kinetics of dicyandiamide + substituted urea cross-linking 3221 was also analyzed. The crosslinking process of the system was predicted and verification. This research work provides theoretical and experimental basis for the formulation research and process parameter selection of medium temperature crosslinked epoxy resin system, which has guiding significance for practical application.
Experimental raw materials. Epoxy resin 3221; crosslinking agent: dicyandiamide, electronic grade ultrafine; N2 phenyl N'N'2 dimethylurea: chemically pure
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Uses:
In this paper, the reaction kinetics of dicyandiamide and dicyandiamide + substituted urea cross-linking agent was analyzed, and the cross-linking process parameters of dicyandiamide + substituted urea cross-linking agent were predicted.
The cross-linking system with dicyandiamide + substituted urea cross-linking agent can reduce the apparent activation energy Ea of 3221 system by 58 kJmol compared with dicyandiamide alone, and the former crosslinking temperature is about 50 ℃ lower than that of the latter Ease.
Different epoxy resin system for the use of different cross-linking agent can have different cross-linking temperature, the general cross-linking temperature higher than 150 ℃ called high temperature crosslinking resin, crosslinking temperature of 90 ℃ ~ 150 ℃ called For the temperature cross-linked resin. At present, the use of lower crosslinking temperature to obtain a resin system with a higher glass transition temperature (Tg) is a thermal study of epoxy resin.
The main problem is to select the appropriate cross-linking agent and accelerator to achieve the purpose of reducing the cross-linking temperature, for example, the use of latent crosslinking agent or accelerator can reduce the cross-linking temperature while ensuring that the resin has a high heat-resistant temperature And longer shelf life.
The epoxy resin system investigated in this paper is a crosslinked epoxy resin substrate 3221 at a medium temperature (125 ° C to 130 ° C). The system is completely cross-linked after the Tg of 170 ℃, the cross-linking agent for the composite cross-linked system dicyandiamide + substituted urea.
In this paper, the effects of different crosslinking systems on the crosslinking reaction of the epoxy resin system were reported. The reaction mechanism was also discussed. The reaction kinetics of dicyandiamide + substituted urea cross-linking 3221 was also analyzed. The crosslinking process of the system was predicted and verification. This research work provides theoretical and experimental basis for the formulation research and process parameter selection of medium temperature crosslinked epoxy resin system, which has guiding significance for practical application.
Experimental raw materials. Epoxy resin 3221; crosslinking agent: dicyandiamide, electronic grade ultrafine; N2 phenyl N'N'2 dimethylurea: chemically pure
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Uses:
The product is identical to Ethancure 100 and Lonza DETDA 80, DETDA is very effective polyurethane elastomer chain extender; also be used as polyurethane and epoxy resin curing agent, epoxy resin of an antioxidant, industrial oils and lubricants . In addition, also as intermediates in organic synthesis.Especially for the RIM (reaction injection molding), is important in the field of spray polyurea chain extender species. Also can be used for casting polyurethane elastomer (CPU) and a curing agent, epoxy curing agent, epoxy resin of antioxidants, lubricants and industrial oils other antioxidants.
Test Methods. Differential Scanning Calorimetry: US PERKIN2ELMERPyris1, heating rate B is 10 ℃ min, the temperature range is 50 ℃ ~ 250 ℃, the atmosphere N2. In the kinetic study, B is 5 ℃ min, 10 ℃ min, 20 ℃ min, 25 ℃ min.
Effect of accelerator on cross - linking reaction of epoxy resin crosslinking system. The 3221 epoxy resin used in the test was prepared by mixing bisphenol A type epoxy with polyfunctional glycidylamine epoxy, with an average epoxy value of 0.50 to 0.52. The addition of dicyandiamide to the mixed epoxy resin and the addition of dicyandiamide and N2 phenyl N'N '2 dimethylurea were carried out for DSC test. The characteristic data of the curve - starting temperature Ti, peak temperature Tp and Peak end temperature Tf see Tab.1.
In the actual cross-linking reaction, Ti represents the temperature at which the reaction begins to occur. Ti low means that the reaction temperature is low and easy to crosslink. Tp represents the fastest reaction temperature and has important guiding significance for the selection of process conditions. Tf Tf-Ti is the temperature range at which the reaction takes place, and the larger the value is, the reaction can be carried out over a wide temperature range, i.e., the reaction is relatively gentle.
The use of dicyandiamide crosslinked system alone, the dynamic DSC spectrum has a cross-linking exothermic peak, as can be seen from Tab.1, the exothermic peak Ti is 151 ℃, Tp is 195 ℃, Tf is 210 And Tf-Ti is 59 ° C. The DSC curve of dicyandiamide + N2 phenyl N'N'2 dimethylurea using a composite crosslinking system also has a crosslinking peak, Ti is 108 ° C, Tp is 139 ° C, Tf Is 209 ° C, and Tf-Ti is 101 ° C.
After using the composite crosslinking system, Ti decreased by 43 ℃ compared with Dicyandiamide alone, Tp decreased by 56 ℃, and the peak width increased by 42 ℃. It can be seen that the temperature of the whole crosslinking process is larger And the crosslinking reaction tends to be relaxed.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Test Methods. Differential Scanning Calorimetry: US PERKIN2ELMERPyris1, heating rate B is 10 ℃ min, the temperature range is 50 ℃ ~ 250 ℃, the atmosphere N2. In the kinetic study, B is 5 ℃ min, 10 ℃ min, 20 ℃ min, 25 ℃ min.
Effect of accelerator on cross - linking reaction of epoxy resin crosslinking system. The 3221 epoxy resin used in the test was prepared by mixing bisphenol A type epoxy with polyfunctional glycidylamine epoxy, with an average epoxy value of 0.50 to 0.52. The addition of dicyandiamide to the mixed epoxy resin and the addition of dicyandiamide and N2 phenyl N'N '2 dimethylurea were carried out for DSC test. The characteristic data of the curve - starting temperature Ti, peak temperature Tp and Peak end temperature Tf see Tab.1.
In the actual cross-linking reaction, Ti represents the temperature at which the reaction begins to occur. Ti low means that the reaction temperature is low and easy to crosslink. Tp represents the fastest reaction temperature and has important guiding significance for the selection of process conditions. Tf Tf-Ti is the temperature range at which the reaction takes place, and the larger the value is, the reaction can be carried out over a wide temperature range, i.e., the reaction is relatively gentle.
The use of dicyandiamide crosslinked system alone, the dynamic DSC spectrum has a cross-linking exothermic peak, as can be seen from Tab.1, the exothermic peak Ti is 151 ℃, Tp is 195 ℃, Tf is 210 And Tf-Ti is 59 ° C. The DSC curve of dicyandiamide + N2 phenyl N'N'2 dimethylurea using a composite crosslinking system also has a crosslinking peak, Ti is 108 ° C, Tp is 139 ° C, Tf Is 209 ° C, and Tf-Ti is 101 ° C.
After using the composite crosslinking system, Ti decreased by 43 ℃ compared with Dicyandiamide alone, Tp decreased by 56 ℃, and the peak width increased by 42 ℃. It can be seen that the temperature of the whole crosslinking process is larger And the crosslinking reaction tends to be relaxed.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
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