At present, color printing cartons are widely used as packaging products, not only with a variety of appearances, but also with excellent application performance. Water resistance is an important aspect. We need to master the correct measurement method to know whether its waterproof performance is good or bad. Pay attention to the correct method when testing. Here, we will introduce some methods for testing waterproof performance.

1. Determination method of Cobb absorption photometer

Test method: cut the color printing carton into 10 circular test pieces with a diameter of 125mm. Before placing the corrugated cardboard test piece, ensure that the cylinder ring and rubber pad in contact with the test piece have been drilled.

Use a glass measuring cylinder to measure 100mL of distilled water and pour it into the measuring cylinder, and then place the weighed round corrugated board sample on the circular surface of the measuring cylinder. The measured surface faces the direction of water. Use a gland to cover the sample and fix it with the measuring cylinder. Rotate the cylinder 180 degrees to start the stopwatch. Add a certain amount of water every five times according to the water absorption of the corrugated board sample.

Remove the sample from the cylinder and place it on a piece of absorbent paper. Note that the absorption surface of the sample is downward. When it is 2s before the water absorption time, put two pieces of water absorption paper on the sample, and use a smooth press roller to move back and forth once on a flat and solid platform for 4s, so that the sample surface appears waterless luster. Quickly take out the sample and weigh it to 0.001 g. Note that each sample can only be tested once and cannot be reused. If there is still excess water on the surface after absorbing water with absorbent paper, or the sample itself has been penetrated by water, it should be discarded. In this way, the water absorption can be calculated.

2. Soaking method

Test method: cut the color printing packaging sample into 10 square samples with the size of 100 mm and 100 mm, put them into a pre weighed clean container, and weigh them on the balance. Take out the sample from the container and insert it vertically into the reagent tank containing distilled water. The upper edge of the sample should be 25mm and 3mm below the water surface, and the sample should be prevented from contacting the bottom of the tank and the sample (small clips can be used to clamp, but the clip opening should be within 5mm of the sample edge).

The soaking time can be determined according to the following conditions:

Low water resistance: 5min 15s; Medium water resistance: 30 minutes and 60 seconds; High water resistance: 24h and 15min.

When the sample is immersed in distilled water for a specified time, use tweezers to straighten one corner of the sample and take out the sample from the distilled water. Keep the sample for 2 minutes and let distilled water drop. Put the sample back into the original container and weigh it to 0.01g on the balance. Then the water absorption and relative water absorption of color printing carton can be calculated.

3. Imitation method

Simulate the circulation environment of products, verify the contents of packing, and record the time and waterproof effect of color printing carton.

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