News Details
Crosslinking agent for epoxy powder coatings
2017-9-4 12:14:32
Crosslinking agent for epoxy powder coatings
Epoxy powder coating is the first developed thermosetting powder coating. By means of amines, organic acids or anhydride, phenol and other different types of crosslinking agents used in epoxy resin, the products of epoxy powder coatings can be obtained. Therefore, it still plays a leading role in many large areas of coating, protective coating and application of functional powder coatings.
Among the many cross-linking agents used in epoxy resins, there are also some varieties that can achieve low temperature/fast crosslinking, so the epoxy system also has good prospects in the field of low temperature/fast crosslinking.
Epoxy-containing epoxy resin is A membrane resin in epoxy powder system. The most commonly used is bisphenol A diglycidyl ether, which is known as e-12. In order to form an insoluble three-dimensional network film, the linear epoxy resin must be cross-linked with appropriate crosslinking agent. The crosslinking agent used for epoxy resin is the compound that can produce crosslinking reaction with epoxy base in resin. Based on the ability to react with epoxy in crosslinking agent
Unlike active groups, epoxy-crosslinking agents can be classified into amino groups containing amines, compounds containing carboxyl groups and compounds containing hydroxyl. There are several kinds of epoxy crosslinking agents that can be used in powder coatings and their development in low temperature crosslinking.
Droplets in contact with the solid surface molecules are attractive depends on their position, in order to achieve balance, system toward minimizing the free energy of per unit area, as a result, the surface to minimize classic droplets. According to the famous Young equation, the three interfacial forces in equilibrium are: gamma sv = gamma sl + gamma lvcos theta
In which gamma sv = the surface tension of the substrate in contact with the vapor in the powder coating
Gamma lv = the surface tension of the powder coating with its own steam
Gamma sl = the interfacial tension between the powder coating and the substrate
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
Epoxy powder coating is the first developed thermosetting powder coating. By means of amines, organic acids or anhydride, phenol and other different types of crosslinking agents used in epoxy resin, the products of epoxy powder coatings can be obtained. Therefore, it still plays a leading role in many large areas of coating, protective coating and application of functional powder coatings.
Among the many cross-linking agents used in epoxy resins, there are also some varieties that can achieve low temperature/fast crosslinking, so the epoxy system also has good prospects in the field of low temperature/fast crosslinking.
Epoxy-containing epoxy resin is A membrane resin in epoxy powder system. The most commonly used is bisphenol A diglycidyl ether, which is known as e-12. In order to form an insoluble three-dimensional network film, the linear epoxy resin must be cross-linked with appropriate crosslinking agent. The crosslinking agent used for epoxy resin is the compound that can produce crosslinking reaction with epoxy base in resin. Based on the ability to react with epoxy in crosslinking agent
Unlike active groups, epoxy-crosslinking agents can be classified into amino groups containing amines, compounds containing carboxyl groups and compounds containing hydroxyl. There are several kinds of epoxy crosslinking agents that can be used in powder coatings and their development in low temperature crosslinking.
Droplets in contact with the solid surface molecules are attractive depends on their position, in order to achieve balance, system toward minimizing the free energy of per unit area, as a result, the surface to minimize classic droplets. According to the famous Young equation, the three interfacial forces in equilibrium are: gamma sv = gamma sl + gamma lvcos theta
In which gamma sv = the surface tension of the substrate in contact with the vapor in the powder coating
Gamma lv = the surface tension of the powder coating with its own steam
Gamma sl = the interfacial tension between the powder coating and the substrate
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
Theta = contact Angle is the Angle between the tangent of the surface of the liquid drop and the surface of the solid.
Cos theta theta = (gamma sv - gamma sl)/gamma lv
Known as the infiltration Angle, > 90 ° said liquid infiltration not solid surface; < 90 ° can said liquid wetting solid surface, = 0 ° = 1 liquid can fully wetting solid surface. Thus, gamma sv tries to spread the liquid along the substrate surface, while gamma sl and gamma lv try to shrink the liquid. Therefore, the surface tension gamma lv of the melt powder coating and the gas is reduced, and the surface tension gamma sl between the melting powder and the substrate can promote the infiltration and spread of the powder coatings to the substrate.
Nix and Dodge equation quantitatively give the influence factors of the powder particles in the fusion phase. The Orchard equation describes the influencing factors of the post-fusion phase. Are two process, and the results show that the high surface tension and low viscosity to flow, but on the other hand, low surface tension and increase the wettability, spreading molten coating on the substrate, thereby reducing defects, at the same time, the melt viscosity is too low will lead to flow to hang and so on. Therefore, two opposing factors should be considered in practical operation to balance the ultimate performance.
For solvent-based coating with the evaporation of the solvent, the surface tension of the coating surface can form high and surface viscosity will increase with the volatilization of solvent, also reduces the surface temperature of the heat along with, so will cause the lower level is poor, the surface tension of the temperature difference and the difference of viscosity, these comprehensive factors resulted in the imbalance of film up and down, up and down in order to make the system to maintain balance will have the impetus, keeps up and paint flow until the final viscosity to stop the flow.
At this point the surface tension difference disappears, and the surface of the final flattening is obtained. In fact in the coating can form irregular flow balance in the up and down, the edge of the hexagonal network, also known as the benard cell (boehner eddy current), source point located in the central part of cellular (low surface tension), and the coating is piled up to the edge of the cell (high surface tension).
Because this convection causes the surrounding uplift of the vortex, if the coating's liquidity is poor, it will see the orange peel phenomenon. Generally this is related to the surface tension gradient and wettability of coatings. When the coating viscosity is low and the coating film is thicker, it is obvious that the viscosity increase and film thickness decrease.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Theta = contact Angle is the Angle between the tangent of the surface of the liquid drop and the surface of the solid.
Cos theta theta = (gamma sv - gamma sl)/gamma lv
Known as the infiltration Angle, > 90 ° said liquid infiltration not solid surface; < 90 ° can said liquid wetting solid surface, = 0 ° = 1 liquid can fully wetting solid surface. Thus, gamma sv tries to spread the liquid along the substrate surface, while gamma sl and gamma lv try to shrink the liquid. Therefore, the surface tension gamma lv of the melt powder coating and the gas is reduced, and the surface tension gamma sl between the melting powder and the substrate can promote the infiltration and spread of the powder coatings to the substrate.
Nix and Dodge equation quantitatively give the influence factors of the powder particles in the fusion phase. The Orchard equation describes the influencing factors of the post-fusion phase. Are two process, and the results show that the high surface tension and low viscosity to flow, but on the other hand, low surface tension and increase the wettability, spreading molten coating on the substrate, thereby reducing defects, at the same time, the melt viscosity is too low will lead to flow to hang and so on. Therefore, two opposing factors should be considered in practical operation to balance the ultimate performance.
For solvent-based coating with the evaporation of the solvent, the surface tension of the coating surface can form high and surface viscosity will increase with the volatilization of solvent, also reduces the surface temperature of the heat along with, so will cause the lower level is poor, the surface tension of the temperature difference and the difference of viscosity, these comprehensive factors resulted in the imbalance of film up and down, up and down in order to make the system to maintain balance will have the impetus, keeps up and paint flow until the final viscosity to stop the flow.
At this point the surface tension difference disappears, and the surface of the final flattening is obtained. In fact in the coating can form irregular flow balance in the up and down, the edge of the hexagonal network, also known as the benard cell (boehner eddy current), source point located in the central part of cellular (low surface tension), and the coating is piled up to the edge of the cell (high surface tension).
Because this convection causes the surrounding uplift of the vortex, if the coating's liquidity is poor, it will see the orange peel phenomenon. Generally this is related to the surface tension gradient and wettability of coatings. When the coating viscosity is low and the coating film is thicker, it is obvious that the viscosity increase and film thickness decrease.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Spanish
French
Italian
Portuguese
Japanese
Korean
Arabic
Russian