Introduction
In the process of coating production and application, solids content is one of the key parameters to evaluate product performance and cost control. The traditional oven method takes a long time to determine the solid content, which is difficult to meet the needs of rapid detection in modern production. In recent years, halogen moisture analyzers based on the principle of thermal weight loss have been gradually introduced into the coating industry due to their high efficiency and convenience to quickly determine the solid content of water-based coatings. The method quickly evaporates the water and volatile components in the sample by halogen heating source, and directly calculates the solid content, which significantly improves the detection efficiency.
Principle of determination
The halogen moisture analyzer is based on the thermal weight loss analysis method. The instrument has a built-in halogen lamp as a heating source, which can heat the sample quickly and evenly. The moisture and volatile substances in the sample evaporate during the heating process, and the instrument monitors the change of sample quality in real time, and when the quality reaches stability, it is judged as the end point of drying. The solid content is calculated as the percentage of the remaining mass after drying to the initial mass, and the calculation formula is as follows:
Solids content = (dried sample mass / initial sample mass) × 100%
The process is typically completed within minutes, significantly reducing the time compared to traditional methods.
Instruments and materials
The measurement requires a halogen moisture analyzer, whose key components include a halogen heating unit, precision balance, and temperature control system. Sample preparation requires the preparation of representative waterborne coating samples, usually recommended between 1 and 5 grams, which should be adjusted according to instrument requirements and sample characteristics. Auxiliary tools include sample trays, samplers, etc., all tools should be clean and dry to avoid introducing errors.
Assay steps
Start by turning on the instrument and preheating and calibrating to ensure accurate measurement references. Place the empty sample tray in the instrument and peel it to zero. Use a sampler to evenly take the appropriate amount of sample and place it on the sample tray to record the initial mass. Set the heating parameters, usually the temperature range is between 100°C and 150°C, depending on the type of coating and relevant standards. Start the heating program and the instrument automatically monitors the quality change until the drying end is reached. After the program, the instrument directly displays the solids content value. It is recommended to measure each set of samples in parallel more than twice to ensure the reliability of the results.
Results and discussion
The data obtained by the halogen moisture analyzer are generally repeatable, and the deviation from the standard oven method is generally within acceptable limits. The following is a brief comparison of the characteristics of the method:
| Determine the speed | It is usually done in 5-15 minutes |
| Sample dosage | Only a small sample is required, usually 1-5 g |
| Degree of automation | Automatic monitoring and calculation to reduce human error |
| Applicability | Suitable for most water-based coating systems |
It should be noted that the heating temperature and time settings should be adjusted according to the coating formula to avoid resin decomposition or abnormal loss of volatile components caused by excessive temperature. For coatings containing special additives, it is recommended to verify the suitability through method comparison.
Notes:
The operating environment should be stable to avoid vibration or airflow interference. The sample should be evenly laid on the sample tray to ensure uniform heating. Regularly clean and calibrate weights to maintain instrument condition. When determining samples from different batches or formulations, it is recommended to re-optimize the heating parameters. Data records should be complete, including sample information, measurement conditions and results.
Epilogue
Halogen moisture analyzers provide a fast and efficient solution for the determination of solids content in waterborne coatings. This method not only ensures data reliability, but also significantly improves the detection efficiency, which is conducive to quality control and process optimization in the production process. With the development of technology, this method is expected to be applied in more coating-related detections.
References
1. Standardization of Coating Solids Content Determination Methods, Industry Technical Collection, 2020.
2. Application of thermogravimetric analysis in coating inspection, Journal of Materials Testing, 2019.
3. Halogen Heating Technology Principles and Instrument Operation Guide, Instrument Analysis Handbook, 2021.