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In the last two articles we already discuss the how the solvent EA influence the lamination quality, and it will make possible problems. And we also introduce which quality we need and how to check the water content. From it, we can fully understand how important it is. But for the converters, how they can control the quality of solvent EA? In this article we will introduce a very practical method to control the quality of solvent EA.
The solvent EA quality control has three steps: quality during purchase (Purchasing Quality), quality during store (Storage Quality) and quality during using (Using Quality). So we need make sure all steps are in good condition.
Firstly, the purchasing department should choose solvent supplier with strong technical background. Secondly, the QC department need check every batch product quality with Karl-Fischer moisture meter and GC, and make sure the solvent quality reach the urethane grade. Only we get good purchasing quality can make sure other steps is meaningful.
Storage Quality is easy for control, but often ignored by the converter. There are two methods to store the solvent: Drum and Tank.
A). If store in drum, the drum should be closed well after each use. It is better to use special tool to ensure a tight lid. And use the fixed drum to store the fixed solvent, don’t mix together.
B). If store in tank, there is a breathing valve on the top of tank. The air desiccant must be added into the breathing valve to avoid the moisture coming into solvent, and the air desiccant must be changed regularly. The above case (water content high to 4000ppm) is due to the customer never changes the air desiccant before.
COMENS do a test: in summer, the humidity is around 80%, temperature is around 30~35°C. A 50MT solvent EA tank, with usage 5MT/day, the pump is added air desiccant. Every time, the pump works 20min, then the tank is sealed. At the beginning, the solvent content is 226ppm, after 3 days, it is 520ppm, after 7days, it is 760ppm, after 10 days, it is already high to 1020ppm. This test shows in high temperature and high humidity environment, the moisture in air can easily go into solvent EA, until the water content of solvent EA balances with moisture content of air. So we need clean the tank regularly to avoid the water residual in the bottom of the tank. And we prefer using pump or high tank to transport the solvent EA. If using compressed air for transporting, the compressed air must be desiccated well.
When purchasing and storage quality is OK, it doesn’t mean using quality is no problem. The main reason is high temperature and moisture in the workshop, and the operator take big quantity, the drum is not closed well. The high temperature and moisture is easily making the solvent EA quality change, so we need control the workshop temperature and moisture. And normally the operator like take big quantity of solvent EA, then they can use it easily. But the best is take small quantity each time, then we can reduce the risk. And for the solvent EA and mixed adhesive in the workshop, we should use closed it well, at least use a cap to cover the container. And for the adhesive coating unit, the best is we use a cover to cover the adhesive pan, it can reduce the solvent EA evaporation and water goes inside, then make sure the adhesive is well used.
Beside water content in solvent, the alcohols content in solvent also should be checked strictly, they also will affect lamination result as heavy as water.
The solvent EA is looks simple, but not too simple, we must pay enough attend on it to avoid lots of potential problems in the next step. If the converters know the solvent EA clearly, we can do some things to solve some problems.
The key points for us are urethane grade, good storage and good take care during using. Also high temperature and moisture is the first enemy for us.
COMENS has the strong technical support team, we will do our best to service you. If you have any question, please send email to sales@co-mens.com.
