Analyze the factors that affect the adhesive strength of corrugated boxes

The factors affecting the adhesive strength of corrugated boxes are not only present in the carton production process, but also in the carton inspection process. Because the adhesive strength of the carton is high or low, it must be shown by the test results. Therefore, the influencing factors of the detection process cannot be ignored.

1 . Sampling of sample, pretreatment conditions and influence of test environment

According to the "Regulations" requirements, the inspection sample box should be randomly selected. The performance inspection sample box shall be drawn from the sample box that has passed the inspection of appearance. The 12 samples taken shall be representative. They shall be cut from different parts of the three sample boxes and shall be prepared for each of the six surface inspection blocks. Distinguish the mark, not easy to figure out, just saw the sample from one or two pieces of cardboard, the "Regulations" also stipulates that the sample must be pretreated in 23 ± 2 °C, relative temperature 50 ± 5% environment 24h , and in this condition Under the test.

GB6544 stipulates that after the constant temperature and humidity treatment of the sample, the moisture content should be between 10 ± 2% , if these precautions, conditions and the environment can not meet the standard requirements will affect the accuracy of the adhesive strength test results.

2 . The use of stripping racks during testing has a great influence on the bond strength value

At present, there are two types of stripping racks used by laboratories to detect the bonding strength of cartons: One is a comb stripping rack manufactured by a company in Changzhou ( TPN-2 type, the stripping rack must be restructured to meet the “Regulations”. The relevant requirements); the other is a stripping rack made by a factory in Sichuan (type WZL-1 ).

In terms of the effect of the two on the bond strength test results, the former type A and C type pins are too thick, and when the holes are inserted into the corrugated hole, artificial adhesion cracks are generated at different levels on the adhesion site where the test piece is to be tested. Followed by some of the pins will produce bending deformation after a period of time, not parallel to the pressure of the plate surface, so that the sample in the 25mm width direction of unilateral uneven peeling phenomenon.

The latter has a thinner pin diameter ( A楞3mm , B , C φ 2mm ). When the sample is inserted into the bore hole, the pin end is supported so that the pin is not easily deformed after being forced. Therefore, the latter can better overcome the defects of the former.

Sometimes the same batch of samples, compared with the above two kinds of stripping rack test, the former test of the bond strength value will be lower than the latter's 5 to 10% , if the pin deformation is large, the result is greater. Therefore, regardless of which type of stripping frame is used, the deformation of its pins must be prevented.

3 . When the test result is converted, the value of the number of turns on the sample affects the bond strength value

"Rule" 5.2 2.7 predetermined, by experiment and calculation method for GB6548, GB6548 and results are shown in Formula 3. 4 error, i.e., A = F / S, A - bond strength, N / m (precisely Should be N/m楞), F - maximum force required when the specimen is fully separated, N ; S - specimen area, cm2 . Obviously, the units on both sides of the equation do not match, that is, N/m楞≠ N/cm2 , and the concept does not hold.

The “Regulations” did not give correct calculation formulas. Actually, people perform calculations according to the calculation methods introduced in certain publications or training courses. For example, in “Corrugated Carton Test Method”, the bond strength formula is: A= F/0.025 × number of turns , or A , F notes are the same as those of GB6548 , the number of turns on a sample. Therefore, there are two cases of the number of corrugations: one is to take the number of full (complete) turns on the sample; the other is to take only the actual number of peeled turns in the sample.

In the same sample, the number of turns of the latter will be 1 to 2 less than the former, which means that when the same test value is converted to the bond strength, it will be larger due to different values ​​of the number of turns. The difference is directly related to the evaluation of the bonding strength of a batch of carton.