Causes of foaming of epoxy resin glue and methods of eliminating bubbles

Causes of bubbles produced in the stirring process: The reason why bubbles are produced in the mixing process of Epoxy Resin glue is firstly the bubbles caused by the gases brought into the mixing process, and the "cavitation effect" caused by the liquid with too fast stirring speed. However, there are two kinds of bubbles visible to the naked eye and invisible ones. Using vacuum defoaming can only eliminate the bubbles visible to the naked eye, which is not good for removing the tiny bubbles invisible to the human eye. Two: The reason for bubbles produced in the curing process: This is because Epoxy Resin is cured by polymerization reaction, which is a chemical reaction. During the curing reaction, the tiny bubbles in the epoxy system expand with heat, the gas is no longer compatible with the epoxy system, and then clumps together to produce larger bubbles. Reasons for the foaming of epoxy resin:

1. Chemical instability

2. Mixing when equipped with thickener

3. Reaction foaming after thickening agent collection

4. Slurry discharge process

5. Hazards of epoxy resin foaming produced in the mixing process: 1. Foam caused by spillover and thickener consumption, will also affect the observed liquid level height. 2. Bubbles caused by molecular amine as Curing Agent will affect construction efficiency. 3. The presence of "wet bubble" will lead to VCM gas phase polymerization, which is generally produced in the sticky kettle. 4. If the bubbles are not completely removed from the construction, bubbles will be produced after curing, and there will be many pinholes on the surface after drying, seriously affecting the quality of the product.

How to eliminate bubbles? Commonly used defoamer product category: Silicone defoaming agent, non-silicon defoaming agent, polyether defoaming agent, mineral oil defoaming agent, high carbon alcohol defoaming agent and so on, when the temperature is low, the characteristics of most liquid substances will change, especially the viscosity of adhesive liquid substances will increase with the decrease of temperature, epoxy resin ab glue as a typical liquid substance, due to the decrease of temperature, The viscosity value also increases significantly. Therefore, in use and use process, bubbles are difficult to eliminate, flat performance is reduced, use time and curing time increase is not conducive to normal production and control. However, through the accumulation of years of production experience, we have summarized some helpful experiences to effectively solve and reduce the problems brought by the above problems. There are four specific methods as follows:

1. The field heating method: When the temperature on the site drops to 25° C, heat the site effectively to raise the temperature suitable for glue operation (25 ° C ~30 ° C). At the same time, the relative air humidity on the site should be maintained at about 70% until the temperature of the glue itself is the same as the ambient temperature. The glue can work and be used normally. Tips: This method is the most effective method, but the operation cost will be relatively high, please pay attention to the cost accounting.

2.Boiling water heating method: cooling will directly reduce the viscosity of epoxy resin ab glue significantly increase, before the use of glue heating, improve their own temperature, reduce the viscosity value, easy to use. The specific method is about 2 hours before the use of glue, put the whole bucket or bottle of glue into boiling water to heat, so that the glue temperature reaches about 30C, take it out, shake it twice, and then always put a glue in warm water at a temperature of no less than 30° C, and use it while heating. During use, remove the glue and shake it every half hour so that the glue always keeps the temperature symmetrical with the ingredients. But pay special attention not to let the glue in the bucket or bottle stick to the water, otherwise it will lead to bad or serious consequences.

Defoamer assistance method: In order to moderately accelerate the removal of bubbles, epoxy resin ab can also be purchased to add glue special defoamer, add the ratio of 3 A glue ‰ interior, specific formula; Add no more than 3% of the epoxy resin ab glue special defoamer into glue A heated by the above method directly, then stir well, and mix with glue B.