News Details
Epoxy resin coating crosslinking agent
2017-8-20 23:52:40
Epoxy resin coating crosslinking agent
Waterborne epoxy resin coating is a kind of emulsion paint, its mechanism of membrane with general polymer emulsion paint, such as acrylic emulsion film has the very big difference, at the same time and solvent epoxy coatings film is not entirely the same.
Waterborne epoxy resin coating is a kind of emulsion paint, its mechanism of membrane with general polymer emulsion paint, such as acrylic emulsion film has the very big difference, at the same time and solvent epoxy coatings film is not entirely the same.
General polymer emulsion coating cross stitch is a physical process, the glass transition temperature of dispersed phase particles is low, in the structure of water evaporated to form close packing, condenses into membrane and under the effect of capillary pressure.
In solvent epoxy coatings system, epoxy resin and epoxy resin coating crosslinking agent are in the form of molecules dissolved in organic solvent, the formation of the system is homogeneous, epoxy resin coating crosslinking agent of crosslinking reaction between the molecules, and epoxy resin coating crosslinking agent crosslinking reaction more fully, the formation of the coating film is homogeneous.
Waterborne epoxy resin coating is a polyphase system, epoxy resin is dispersed in the water phase in the form of dispersive phase, epoxy resin coating crosslinking agent
Dissolved in water.
The mixture of the two components is coated on the substrate, and the water evaporates rapidly under the appropriate temperature conditions. When most of the evaporation, epoxy resin latex particles contact each other, form a tightly packed structure, residual moisture and crosslinking agent molecules in epoxy resin dispersed phase particle clearance.
With the further evaporation of moisture, the dispersed phase particles of epoxy resin begin to coagulate and form a more compact hexagonal arrangement. At the same time, the crosslinking agent diffuses into the interface of the dispersed phase particles of the epoxy resin and its internal crosslinking reaction. The mechanism can also be interpreted as the transformation of water-based epoxy resin system from the state of the water pack oil to the oil-covered water, which is the reverse of the process of the preparation of epoxy resin emulsion by the inverse method.
Assume that turn in the opposite in the preparation of waterborne epoxy resin emulsion the average particle size of dispersed phase particles of 0.5 microns, and set up its density is 1.16 g/mL, epoxy resin molecular weight is 1000, swelling is not considered in the water, can be calculated for each epoxy resin latex particles containing 4.6 x l07 molecule, so the crosslinking of waterborne epoxy resin system is by the crosslinking agent to epoxy resin is determined by the diffusion rate of the dispersed phase particles, which compared with solvent epoxy resin system got behind its hand in membrane process is more complicated.
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Raw material ：
TDA industrial, Sichuan production
Ethylene (Et) polymer grade, Shanghai production
TEA industrial imports
Chinese name: Diethyl toluene diamine(DETDA)
Diethyltoluenediamine Raw material ：
TDA industrial, Sichuan production
Ethylene (Et) polymer grade, Shanghai production
TEA industrial imports
A reagent grade additives
Crosslinking agent molecules first and epoxy resin dispersed phase particle surface contact with crosslinking reaction, as the crosslinking reaction of epoxy resin molecular weight and glass transition temperature of the dispersed phase increase gradually, the crosslinking agent molecules to epoxy resin dispersed phase particles within the diffusion speed gradually slow down, which means that internal crosslinking reaction of epoxy resin dispersed phase particles less than its surface, internal crosslinking density is low.
At the same time, as the crosslinking reaction is carried out, the dispersed phase particles of epoxy resin gradually harden, and the particles can not interact with each other and coagulate into films. Therefore, the water-based epoxy resin coating is difficult to form the homogeneous and complete cross-linking coating compared with the solvent based epoxy coatings.
Therefore, for the water-based epoxy resin coating, whether the crosslinking is fully depends on the following two factors.
Epoxy resin particle size of dispersed phase particles In waterborne epoxy crosslinking agent, under the condition of same ring oxygen resin dispersed phase particle size is small, concentrations of crosslinking agent on the surface of the particles is relatively moderate, slower surface crosslinking, the crosslinking agent molecules have enough time to spread to the whole epoxy resin dispersed phase particles, crosslinking completely, thus can form uniform, crosslinked coating completely.
Conversely, when the size of the dispersed phase particles is larger, the crosslinking agent of the particle surface is relatively high, resulting in the rapid crosslinking of the surface. Epoxy resin as the crosslinking reaction of the apparent viscosity of dispersed phase particles increased, the glass transition temperature will also increase gradually, the crosslinking agent molecules to epoxy resin particle internal diffusion speed gradually slow, epoxy resin particles inside too late cross-linking incomplete crosslinking in the film.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
Spanish
French
Italian
Portuguese
Japanese
Korean
Arabic
Russian