According to the customer's requirements for various physical strength indexes of corrugated boxes, the technical specifications of the boxboard and corrugated paper selected by the quality requirements are calculated item by item, and the highest item is finally taken so that all physical strength requirements can be met, according to the technical specifications of the base paper. You can select the corresponding cardboard and corrugated paper.
Third, the corrugated board burst strength (Kpa)
Under the test conditions, the maximum pressure that the corrugated board can bear on the unit perpendicular to the surface of the test cup is the burst strength of the corrugated paperboard. The burst strength test method is to take four pieces of breaking test specimens of 100mm x 1OOmm with no printing, no watermark, no crease or obvious damage from each sample box in each of the three sample boxes. For the sample chuck, clamp the sample in the middle of the two sample chucks, and then start the analyzer. Gradually increase the pressure at (170 ± 15) mL/min. When the sample is blasted, read the pressure gauge. Indicate the value, then release the chuck and return the reading pointer to the starting position. The data should be discarded when there is significant slippage of the sample. The measurement was performed on each of 10 specimens facing the film on the positive F-side and expressed as the arithmetic mean of all measured values.
Bursting strength is an important indicator of the quality of corrugated board. In the early days, the specification of all corrugated boards was based on the burst strength. Experiments show that the burst strength of corrugated board is only related to surface paper and core paper. The corrugated paper has little effect on the burst strength. It is estimated that the burst strength of corrugated board can be calculated by the following formula:
B=∑Bi
In the formula: B—Corrugation of corrugated paperboard The bursting resistance of Bi-face paper and core paper
Fourth, the side pressure of corrugated board (N/m)
In the corrugated direction, a certain thickness (25mm) of corrugated paperboard, the unit of length can withstand the vertical and uniform increase in force is the corrugated paperboard side pressure strength. The test method of edge pressure strength is to take three blocks of the short-side (25x100)mm test block from the position of each sample box in the three sample boxes without mechanical indentation print marks and damage. Emphasize that the test sample of side pressure strength must be strictly sampled using a standard sampler, otherwise it will have a great influence on the test result). Place the sample in the middle of the lower plate of the tester so that the corrugation direction of the sample is perpendicular to Two pressure plates, using guide blocks to support the sample, so that the surface of the sample hangs. Straight to the platen, start the tester and apply pressure. When the pressure is close to 50N, move the guide block until the sample is crushed. Record the maximum pressure that the sample can withstand. Calculate the arithmetic average of the test results and calculate the edge pressure strength according to the following formula:
P=F* 1000/L
Where: P - side pressure strength (N/m)
F—sample withstands maximum pressure (N)
L—length of the specimen (mm)
When the sample is a standard length L=100mm, P=1OF
The edge pressure strength of corrugated paperboard basically depends on the ring-press strength of boxboard and corrugated base paper, and is related to the production technology of corrugated board, the structure of corrugated board, the shape of corrugated board, the quality of adhesives and other factors. The formula is:
'
Corrugated cardboard side pressure strength (N/m)P = sum of the cyclic pressure strength values ​​of each layer of base paper x (L+δ)
In the formula: The sum of the 8 - ripple coefficient, the reference value is as follows:
Type A corrugated is generally: 0.12
Type B corrugated is generally: 0.08
. Type C corrugated is generally: 0.10
Ring pressure strength of base paper: Ring pressure index x quantification
Since the amount of paper in the dough is usually higher than that of the corrugated paper, the lateral pressure of the paper in the paper is also relatively high. Therefore, the side pressure is mainly determined by the amount of paper in the sheet, but the side pressure is increased. The easiest and most economical method is to increase the ration of the corrugated base paper.
Fifth, the adhesive strength of corrugated board (N/m·楞)
Adhesive strength refers to the degree of bonding between corrugating medium and face paper or paper, and is an important factor in ensuring that the corrugated board becomes an integral structure. Adhesive strength test method is: take four adhesive test specimens of 25mmx80mm in size from each sample box of three sample boxes totaling 12 pieces, and insert the special needle attachments into and out of the test papers and The surface of the paper (or between the crepe paper and the core paper), and then insert the needle-shaped attachment of the specimen placed in the human compressive strength tester pressure, so that it does the relative role, until the specimen is stripped.
Increasing the amount of adhesive applied can generally increase the adhesive strength. In principle, it is sufficient that the adhesive strength is equal to the original fiber self-bonding strength. Excessively high bond strength is often the result of too much adhesive applied to the top of the dome, which will cause the corrugation peak to overlap the face paper to be too large, causing the corrugation peak to change from a U-shape to a rectangle, reducing the As a result, a "sawboard" appearance appears, and as a result, the other properties of the corrugated board deteriorate. Under normal circumstances, the width of viscose on the corrugated surface is 1.5 mm, and the maximum width is not more than 2 mm. The amount of starch binder is approximately 10-15 g/m2. The bond strength sampling rule is to take a corrugated board with a crucible length of 25 mm and a width of 80 mm, which requires data processing when calculating the bond strength value. First calculate the number of ridges in the 80mm width, and multiply the length of each ridge by 25mm to make it the total length of the enthalpy that the tested corrugated board has.
Use the following formula to find the actual number of turns of the test sample (integer):
X=L2xQ/L1
In the formula X: - the actual number of turns of the sample in a certain length unit, and the LI: - the length of the different type of test specified in the standard (300mm)
L2: - sample length (80mm)
Q: - Standards stipulate the number of pods per unit length (a)
For the test results, the arithmetic mean was calculated and the bond strength was calculated according to the following formula.
A=F/Xxl
In the formula: A: - Adhesion strength, N/m楞 F: The force required when the sample is completely separated; N
L:—The length of the sample in the direction of the crucible (m) is 0.025m
(to be continued)
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