Comparison and Application of Testing Methods and Result Expressions of Corrugated Board Adhesive Strength

The adhesive strength of corrugated cardboard is one of the important indicators for evaluating the physical properties of corrugated boxes. For a long time in the field of corrugated paper box production and inspection, there has been no consensus on the standards, test methods, and results of the adhesive strength of corrugated cardboard. This paper proposes to compare this issue with the newly revised GB6548-98 "Determination of the Adhesive Strength of Corrugated Paperboard" (implemented on February 1, 1999). Understand and correctly understand and evaluate the bonding quality of corrugated cardboard so that the new national standard can be implemented as soon as possible.
First, the test principle and test method of corrugated board adhesive strength Corrugated board adhesive strength refers to the corrugated paper and paper, paper and paper core between the firm degree. The test principle is to insert a needle-shaped peeling rack between the crepe paper and the facial tissue of the sample or between the crepe paper and the inner paper and the core paper, and then use a special compressing instrument to pressurize the needle-shaped stripping rack with the sample inserted therein. The relative motion is performed until the separated parts are separated. At this time, the maximum separation force that the peaks and the facial paper or the peaks are combined with the inner paper and the core paper are calculated according to the formula and then the adhesive strength value.
There are two methods for testing adhesive strength in the current testing practice: one-side method and double-test method. The single-side method is based on different corrugated types. Three different diameters of rigid pins are used respectively. The single-layer corrugated space on the same side is inserted in turn along with the support frame to perform peeling. This method can accurately measure the adhesion between any combination of surface peaks and face paper or peaks, and between paper and core paper. The disadvantage is that the operation is compared. Cumbersome, so less used in practice. The double-sided method uses 14 types of comb-shaped pins with different diameters and different gauges according to different types of jaws. When the test is performed, the upper and lower comb needles are inserted from both sides of the specimen, and the two joint surfaces of the same dome layer are simultaneously peeled off. The weak side of the strength is separated first. The test data reflects the force value of the bonding surface with poor bonding strength of the same silicon layer. This method is widely used due to the ease of operation and high speed of the corrugated box production and inspection unit.
It should be pointed out that the bilateral peeling method is not specified in non-standards. From the inspection practice, the comb pins used in the double-sided method are too thick due to the pin type when measuring the B-type corrugated sample. The arrangement is too tight. When the corrugated fiber is inserted into the sample, there will be different degrees of artificial cracking at the adhesion of the sample. At the same time, since the pin is supported by no support, the pin will be bent and deformed after being used for a period of time. The pressure plate surface is not parallel (standard deviation of the parallel plate surface shall not exceed 1 percent), so that the unilateral uneven peeling occurs in the width direction of the sample, which will seriously affect the test results. On the contrary, the single-sided method is equipped with separate pins of different diameters, and there is a corrugated space interval between the pins, and there is a supporting attachment on the end face of the pins, so that the pins are not easily deformed after being subjected to force, and thus the overcoming is better. The former has defects. This method is the standard method specified in the new and old standards of GB6548. Tests have also found that for the same sample under the same conditions using the two-sided method and the one-sided method, the test data is lower (5-10%) than the latter. If some of the other factors above are considered, the difference is poor. The value is even greater.
Second, the calculation formula and results of the corrugated board adhesive strength expressed that the corrugated board adhesive strength calculation formula and results show that the previous national standards and industry regulations are different, and the concept is more confusing. At present, the actual testing involves standards such as GB6548 "Determination of the Adhesive Strength of Corrugated Paperboard", GB5034-85 "Corrugated Cardboard for Export Packaging", and SN/TO262-93 "Procedures for the Inspection of Corrugated Carton Shipping Containers for Export Goods". The “Detailed Rules for Inspection of Corrugated Paper Box Production Licenses” (the “Detailed Rules”) approved by the Technical Supervision Bureau in June 1992.
1.GB6548-88 provides that the formula for calculating the bond strength is P=F/S; (1) where P-bonding strength, N/m, and F-sample are all required to separate the maximum force, N; S-sample area, cm2; (P, F, S meaning the same below) is not difficult to see, (1) type of medium-side two units do not match, ie N/m≠N/cm2, and the concept is not established, obviously the standard is wrong . This result of adhesive strength in practice means that it is not used.
2. The result of the bond strength is expressed in N/m2 in the “Detailed Rules”, from which (1) the unit of S in the formula is m2. At present, this result of the bond strength indicates that the understanding is relatively uniform in the technical supervision system. The quality of the competition is commonly used. This representation essentially refers to the maximum separation force required to strip the corrugated board per unit area.
3. The results of the bond strengths given in G5034-85 and SN/T0262-93 are expressed as kgf/楞·10cm and N/m·楞, respectively. The two units are the same in meaning, and the two are just one coefficient. Conversion relationship. The test methods specified in the two standards are all GB6548, and neither formula is given. According to the meaning of the units expressed, the formula should be P=F/L·n; (2) where L-sample orientation Length, m; n - number of corrugations contained in the specimen, 楞; the resulting bond strength value (N/m·楞), which essentially means the maximum required to strip a single corrugated sheet in a unit length Separation force. At present, the use of this formula and result expression is more common in the inspection of corrugated paper boxes for export of commodity inspection systems. (To be continued)