Water resistance refers to the ability of paper or cardboard to prevent water from penetrating from one surface of the sample to the other. The test instrument is a water resistance Tester. The specific test steps are as follows.
The test principle of the water resistance Tester is shown in Figure 2-26. It consists of a water storage volume, a scale, a lifting device, an indicator, and a sample. The metal collar is fixed on the metal ring, and the rubber pad is installed between the metal collar and the metal cup. The inner diameter of the cylindrical metal cup, collar and rubber pad is (112.5±0.2) mm, and the outer diameter is 170 mm. The thickness of the collar is about 10mm. The highest pressure is 1000mmH2O.
Figure 2-26 Water Resistance Tester
1-water volume; 2-scale; 3-lifting device; 4-indicator; 5-sample clip; 6-sample
①Sample collection and processing. Sampling according to GB 450, cut 2 pieces of 175mm×175mm samples along the transverse direction of the paper web, and mark the front and back sides. According to the requirements of GB 10739, carry out temperature and humidity pretreatment on the samples.
②Place the sample between two rubber pads, then sandwich the rubber pad between the metal cup top and the metal collar, open the water inlet and drain valves, put water in until the air under the sample is exhausted, Close the drain valve. Increase the water pressure on the sample until the pressure gauge reads the required value (usually 500mmH2O). Maintain this pressure and watch the water seep in, noting the time when the first signs of water appear.
③Remove the sample to prepare for the next test, and mark the side of the sample that is wetted by water.
If the penetration time is greater than 10 days, stop the test and state it in the report. The test results are expressed as the arithmetic mean of all test values.
