Method for Detection of Impurities in Solvents
Publication Date: 2003-Nov-05
The IP.com Prior Art Database
METHOD FOR DETECTION OF IMPURITIES IN SOLVENTS Disclosed is a method to determine whether there is an impurity in a solvent. In the coatings industry, coating materials can be shipped in reusable containers, such as totes or drums. The reusable containers are washed between uses to prevent contamination in new products placed in the containers. Typically, the containers will receive a final rinse with a solvent. It is difficult to determine if the container is clean. Contamination from previous material in the container can cause defects, such as craters or "fish-eyes", in coatings formed from the material placed in a contaminated container. Silicone oils are a major cause of defects. Method 1. A test sample of 10 to 15 ml of solvent from the final rinse of the container is obtained and placed in a spectroscopically clean vial. An example of a vial is a WHEATON 25 ml scintillation vial with an aluminum lined cap. 2. A second vial is also provided that contains clean solvent of the same volume as a control. 3. Both vials are shaken. 4. The test sample is compared to the control sample for color, clarity, and particulates. If the test sample shows color, lacks clarity, and/or contains particulates, the container is sent for further cleaning. 5. If the test sample passes step 4, both vials are shaken vigorously together for 5-10 shakes. 6. The rate of disappearance of bubbles in the two samples is compared. Bubbles of all sizes should be considered when evaluating the samples. The bubbles on the top of the solvent are the most visible; however, bubbles can be seen throughout the solvent. 7. If the bubble dissipation rate in the test sample is the same as the rate in the control sample, the container passes inspection. 8. If the bubble dissipation rate in the test sample is slower than the control sample, the container fails inspection and is sent back for further cleaning. The solvent can be any solvent, such as 2-butoxy ethanol, acetone, methyl ethyl ketone, or an alcohol. The method can also be used to determine whether there is any extractable material from a article that may come into contact with a coating material. Examples of articles include filter bags, gloves, cloths, coats, coveralls, hair nets, booties, rags, gaskets, or any other materials. The method above is used. The test sample is prepared by providing a vial of clean solvent and adding a small piece of the material to the vial.