The solid content of the coating refers to a ratio of the mass of the residue after heating and baking at a certain temperature to the mass of the sample, expressed in mass fraction. The standard is GB/T1725-79 "Determination of Solid Content of Coatings". The practical analysis methods in the factory are: petri dish method and surface dish method.
equipment
①Sensitivity of balance 0.0lg;
② Thermometer 0~200℃;
③Glass petri dish diameter 75~80mm, side height 8~10mm;
④ Blast constant temperature oven 0~200℃;
⑤ Glass desiccator (silica gel desiccant).
Measurement steps
(l) Petri dish method
① Bake the dry and clean petri dish in an oven at 103~107°C for 30 minutes, take it out and place it in a desiccator, and weigh it after cooling to room temperature;
②Weigh 1.5~2g of the sample (2~2.5g for perchlorethylene paint, 4~5g for acrylic paint and paint with solid content less than 15%), put it in a weighed petri dish, Spread the sample evenly on the bottom of the container, then put it into a pre-adjusted temperature blast thermostat and bake for a certain period of time (1.5~2.5h), then take it out and put it in a desiccator, cool to room temperature, and weigh. Then put it in an oven for 30min, put it in a desiccator, cool it to room temperature, and weigh it. When the difference between the two weighings is not greater than 0.01g (all weighings are accurate to 0.01g), the test shall measure two samples in parallel.
(2) Surface dish method
① Bake the dry and clean watch glass in an oven at 103~107°C for 30 minutes, take it out and place it in a desiccator, and weigh it after cooling to room temperature;
② Weigh 1.5~2g of the sample (2~2.5g for perchlorethylene paint, 4~5g for acrylic paint and paints with solid content less than 15%), and place in a weighed watch glass. Spread the sample evenly on the bottom of the container, then put it into a pre-adjusted temperature blast thermostat and bake for a certain period of time (1.5~2.5) h, then take it out and put it in a desiccator, cool to room temperature, and weigh. Then put it in an oven for 3omin, put it in a desiccator, cool it to room temperature, and weigh it. When the difference between the two weighings is not greater than 0.01g (all weighings are accurate to 0.01g), the test measures two samples in parallel.
calculate
notes
①The sampling amount of different coating samples may be different, and the solid content is low, so the sampling amount should be slightly more. For electrophoretic coatings, resin: 1.0~1.5g; bad liquid: 2.0~2.5g; ultrafiltrate: 10~15g.
② See Table 21-6 for relevant regulations on measuring temperature
measurement error
The difference between the two measured values should not be greater than 3% of the average value, otherwise it should be measured again,
