The effect of coating crosslinking agent on performance

The effect of coating crosslinking agent on performance

In two-component water-borne epoxy coating system, film of crosslinking is a physical and chemical reaction, crosslinking agent and in the process of evaporation of water of epoxy resin particles surface contact, chemical crosslinking reaction, and crosslinking agent molecules to epoxy resin particle internal diffusion, under the capillary pressure of latex particles and crosslinked epoxy resin to pile up, until the formation of uniform, continuous film.

Crosslinking agent will affect the degree of crosslinking and crosslinking structure of paint film, thus influence on the performance of the paint film mechanical properties and corrosion, so the dosage of crosslinking agent is crucial. In this experiment, a series of experiments were conducted to determine the dosage of crosslinking agent.

By the experimental results it can be seen as the crosslinking agent amount is less than or greater than 1:1 3-1, paint film is poor water resistance, all is due to the low crosslinking density, leads to oxygen and moisture more easy penetration; And because amines are hydrophilic, the overdose of crosslinking agents can cause severe rust.

When the ratio of crosslinking agents is between 2:1 and 1.5:1, the epoxy group and the crosslinking agent can react, form the compact crosslinking structure, and the performance indicators of the paint film meet the requirements; Therefore, the proportion of epoxy and crosslinking agent in the formula system is between 2:1 and 1.5:1.

The membrane process of water-based epoxy coatings is stricter than the solvent, because the process has two steps: one is the evaporation of water; Two is the crosslinking of the paint film. If the crosslinking speed is higher than the evaporation rate of moisture, the paint film will contain water, and the reduced density of the crosslinking will lead to lower performance. This makes the temperature, relative humidity and ventilation in the construction process more stringent than the solvent. In this experiment, the performance of coating film under different construction conditions was tested.

Epoxy crosslinking agent and crosslinking reaction is exothermic reaction, relative to other water-based paint, high temperature tolerance, construction under the condition of above 5 ℃ can crosslinking, at the same time as the environment temperature is higher, the paint film comprehensive performance is better.




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


Because of waterborne epoxy coatings containing a large number of moisture, relative humidity will lead to moisture evaporation rate is too low, resulting in a decline in crosslinking density and film water resistance decreased obviously. By the experimental results it can be seen that the humidity is less than 70%, the temperature is more than 10 ℃ as the best construction conditions.

Was developed using vinyl three (beta - methoxy) ethoxy silane as a modifier of the waterborne epoxy emulsion, when the addition amount of 3% ~ 3%, significantly improved the stability of epoxy emulsion.

The effects of acid value on emulsion stability and coating properties were studied, and the acid value was determined between 60-90 (KOH) mg/g, and the emulsion stability and film performance were the best.

The optimum ratio of epoxy emulsion and crosslinking agent was determined, and when the ratio of epoxy emulsion to crosslinking agent was between 2:1 and 1.5:1, the coating was the best.

To study the influences of construction conditions on the film crosslinked, when humidity is less than 70%, the temperature is more than 10 ℃ as the best construction conditions.

In water-based paint formula, the substrate is the key component to form the paint film and determine the performance of the film. Formulation design of water-based resin dosage should be increased, and the accounts for 60-70% of volume ratio, make the effective film forming matter content in the liquid paint as much as possible, so as to ensure the lacquer is made a coating film is thick, high fullness.

Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd 

Diethyl toluene diamine(DETDA)  http://www.yaruichem.com